Current Developments in Biotechnology and Bioengineering: Sustainable Food Waste Management: Resource Recovery and Treatment 0128191481, 9780128191484

Table of contents :
Front-Matter_2021_Current-Developments-in-Biotechnology-and-Bioengineering
Front Matter
Copyright_2021_Current-Developments-in-Biotechnology-and-Bioengineering
Copyright
Contributors_2021_Current-Developments-in-Biotechnology-and-Bioengineering
Contributors
Chapter-One---Sustainable-Food-Waste-M_2021_Current-Developments-in-Biotechn
Sustainable Food Waste Management: An Introduction
Introduction
Food Waste Generation and Collection
Food Waste Prevention
Food Waste Management and Treatment Technologies
Conventional Food Waste Management Technologies
Newer Food Waste Management Technologies
Conclusions and Perspectives
References
Chapter-Two---Food-Waste-Pr_2021_Current-Developments-in-Biotechnology-and-B
Food Waste Properties
Introduction
Food Losses and Food Waste
Definition
Sources and Quantities of Food Waste
Properties of Food Waste
Proximate Analysis
Chemical Properties
Nutrient Properties
Elemental Composition and Light Metal Ions
Carbohydrate, Protein, and Lipid Contents
Conclusions and Perspectives
References
Chapter-Three---Food-Waste-Generat_2021_Current-Developments-in-Biotechnolog
Food Waste Generation and Collection
Introduction
Food Waste Generation
Food Waste Definitions
Quantification-The Problem of Food Waste in Figures
Europe
Asia
America
Food Waste Properties
Physical Properties
Chemical Characteristics
Elemental Properties
Bromatological Properties
Food Waste Collection
Factors Influencing Planning and Implementation of Food Waste Collection Systems
Current State of Food Waste Collection Systems
Number of Streams Targeted for Collection
Collection Methods
Collection Infrastructure-Staff-Frequency
Containers
Indoor
Outdoor
Bulking Containers
Special Collection Systems
Vacuum Collection Systems
Kitchen Grinders
Household-Scale Drying Systems
Bags or Liners
Collection Vehicles
Capacity
Compaction Level and Prevention of Leakage
Lifting Mechanism and Loading Points
Staff/Personnel Involved in Food Waste Collection
Collection Frequency
Cost Considerations
Investment Cost Categories
Operation and Maintenance Cost Categories
Monitoring and Evaluating Food Waste Collection Schemes
Communication Plan and Raising Awareness Activities
Conclusions and Perspectives
References
Chapter-Four---Closing-the-Food-Chain-L_2021_Current-Developments-in-Biotech
Closing the Food Chain Loop Through Waste Prevention
Introduction
Toward a Sustainable and Circular Food Supply Chain
Target 12.3 of UN Sustainable Development Goals
The European Union Circular Economy Package
The Food Waste Hierarchy
Prevention of Food Surplus and Avoidable Food Waste
Creating Markets for Imperfect Fruits and Vegetables
Redistribution of Food Surplus for Human Consumption
The Current Situation Through Good Practices and Initiatives
Food Banks
Public and Private Funded Initiatives
Bottlenecks for Food Donation
Regulation Issues
Operational Issues
Recycling Food Waste to Animal and Fish Feed
The Current Regulatory Framework
Toward Animal Feed From Food Waste
Conclusions and Perspectives
References
Chapter-Five---Food-Waste-Composting--Ch_2021_Current-Developments-in-Biotec
Food Waste Composting: Challenges and Possible Approaches
Introduction
Global Food Waste Scenario
Composting
Composting Requirements
Food Waste Properties
Controlling the Acidity During Composting
Addition of Alkaline Materials
Microbial Inoculation
Nitrogen Loss and Its Control Measures
Nitrogen Dynamics in Composting Mass
Factors Influencing Nitrogen Loss During Composting
Temperature and pH
Carbon/Nitrogen Ratio
Aeration Rate
Approaches to Reduce Nitrogen Loss During Composting
Precipitation of Nitrogen Into Struvite Crystals
Use of Lime to Reduce the Salinity in Struvite-Based Composting
Use of Adsorbents
Conclusions and Perspectives
References
Further Reading
Chapter-Six---Bioconversion-Technologies-_2021_Current-Developments-in-Biote
Bioconversion Technologies: Anaerobic Digestion of Food Waste
Introduction
Principles of Anaerobic Digestion
Characterizing Biochemical Parameters and Synergistic Effects
Substrate composition
Inoculum/microbes
pH/alkalinity
Gas environment
Pretreatment
Codigestion
Inhibition Factors During Anaerobic Digestion of Food Waste
Ammonia
Long-chain fatty acids
Sodium
Sulfide
Anaerobic Digestion Technologies for Food Waste
Phase-separated digesters
Bioelectrochemical system
Resource Recovery
Biogas
Biohydrogen (Bio-H2)
Biohythane (CH4 and H2)
Volatile Fatty Acids (VFAs)
Integrated Treatment of Food Waste Toward Zero Waste Discharge
Conclusions and Perspectives
References
Chapter-Seven---Microbial-Conversion-of-Fo_2021_Current-Developments-in-Biot
Microbial Conversion of Food Waste: Volatile Fatty Acids Platform
Introduction
Food Waste
Food Waste Composition
VFAs Production During Anaerobic Digestion
Overview of the Anaerobic Digestion Process
Effects of Operation Conditions on VFAs Production and Composition
pH
Temperature
Retention Time
Organic Loading Rate
The Presence of Oxygen
Substrate
Application of VFAs
Application and Market Value of Individual VFAs
Application of the VFA Mixture
Bioplastics
Biological Nutrient Removal
Bioenergy and High-Value Chemicals
Recovery and Purification of VFAs
Centrifugation
Adsorption
Chemical Extraction
Membrane-Assisted Recovery
Pressure-Driven Membrane Processes
Microfiltration and Ultrafiltration
Nanofiltration and Reverse Osmosis
The Principle and Control Strategies of Membrane Fouling
Extractive/Diffusive Membrane Processes
Pervaporation
Electrodialysis
Membrane Contactors and Forward Osmosis
Analytical Determination of VFAs
Conclusions and Perspectives
References
Chapter-Eight---Bioconversion-Technolog_2021_Current-Developments-in-Biotech
Bioconversion Technologies: Insect and Worm Farming
Introduction
Fly Larvae for Food Waste Reduction
Black Soldier Fly Larvae
BSFL for Waste Reduction
Housefly Larvae
Waste Types Suitable for Biodegradation by Housefly Larvae
Housefly Larvae as a Feed Source
Earthworms
Cockroach
Life-Cycle of Cockroach
Nutritional Contents of Cockroaches
Application of Cockroaches in Food Waste Treatment
Pharmaceutical Value of Cockroaches
Crickets for Food Waste Reduction
Crickets for Food Waste Reduction
Cricket Nutrient Content
Conclusions and Perspectives
References
Chapter-Nine---Bioconversion-Technologies-_2021_Current-Developments-in-Biot
Bioconversion Technologies: Hydrolytic Enzyme Treatment of Food Waste
Introduction
Food Waste Characteristics and Significance of Enzymatic Hydrolysis
Conventional Food Waste Management Models
Hydrolytic Enzymes in Food Waste Treatment
Amylases
Cellulases and Xylanases
Proteases
Lipases
Parameters Effecting Enzyme Activity During Food Waste Treatment
Enzyme Loading
Temperature
pH
Solid to Liquid Ratio
Inducers and Inhibitors
Food Waste Treatment Through Solid/Submerged State Fermentation Strategy
Conclusions and Perspectives
Acknowledgment
References
Chapter-Ten---Bioproducts-From_2021_Current-Developments-in-Biotechnology-an
Bioproducts From Food Waste
Introduction
Food Waste Generation
The Problem of Food Waste Generation
Utilization of Food Waste as a Potential Feedstock for Biobased Conversions
Types of Food Wastes Used as Feedstocks and Methods for High-Value Product Conversions
Food Waste Valorization Processes and Conversion to High-Value Products
Bulk Chemicals
Bioconversion of Citrus FW to Citric Acid
Fermentation of FW to Succinic Acid
Specialty or Fine Chemicals From Food Waste
Production of Essential Oils From FW
Biosurfactant Production Using FW as Feedstock
Biobased Materials Derived From FW
Soil Amendment Materials and Green Composites
Biopolymers
PHA Production via Pretreatment-Aided Microbial Fermentation
Multistage Valorization of FW for PHA Synthesis
Pectin Extraction
Animal Protein Synthesis
Bioadhesives Derived From FW
Combustion of Wheat Straw for Synthesis of Bioadhesives
Production of Biofuels From FW Valorization Processes
Gaseous Biofuel Production Using FW: Methane and Hydrogen
Liquid Biofuel Production Using FW: Ethanol and Butanol
Conclusions and Perspectives
Acknowledgment
References
Chapter-Eleven---Conversion-of-Food-_2021_Current-Developments-in-Biotechnol
Conversion of Food Waste to Animal Feeds
Introduction
Types of food waste
Plant-derived food waste
Animal-derived food waste
Nutritional value of food waste
Food Waste to Animal Feed-Processing Methods
Dehydration
Solar drying
Tunnel drying
Spray drying
Freeze drying
Microwave drying
Vacuum drying
Silage
Liquid feeding
Direct Conversion
Indirect Conversion
Food Waste to Animal Feed-Types
Cattle feed
Fish feed
Pet feed
Poultry feed
Duck feed
Swine feed
Conclusions and Perspectives
References
Chapter-Twelve---Pyrolysis-and-Gasif_2021_Current-Developments-in-Biotechnol
Pyrolysis and Gasification of Food Waste
Introduction
Principles of Pyrolysis and Gasification
Pyrolysis and Gasification Reactors
Factors Affecting the Pyrolysis and Gasification of Food Waste
Effect of Moisture Content on the Pyrolysis and Gasification of Food Waste
Effect of Temperature on the Pyrolysis and Gasification of Food Waste
Copyrolysis of Food Waste With Different Types of Materials
Products of the Food Waste Pyrolysis and Gasification Processes: Gas, Liquid, and Solid Components
Biooil
Biochar
Syngas Characteristics
Conclusions and Perspectives
Acknowledgments
References
Chapter-Thirteen---Emerging-Technologies_2021_Current-Developments-in-Biotec
Emerging Technologies for the Treatment of Food Waste
Introduction
Different Types of High-Value Products Recoverable From Food Waste
Molecules Derived From Vegetable Food Waste
Molecules Derived From Animal Food Waste
Chitosan
Protein Hydrolysates
Collagen
Calcium-Based Adsorbent
Carbon-Based Adsorbent
Pyrolysis
Gasification
Hydrothermal Carbonization
Microwave-Assisted Thermochemical Conversion
Biodrying (Bioevaporation)
Background of Biodrying
Principles
Biodrying Process and Reactor
Influencing Factors on the Biodrying Process
Impact of Moisture Content and FAS
Conditioning With Bulking Agents
Aeration and Agitation
Comanagement of Domestic Wastewater and Food Waste
Codigestion of Food Waste and Sludge
Importance of Codigestion Ratio
Challenges and Opportunities
Food Waste as External C Source to Enhance BNR in Wastewater
Direct Use of Food Waste
Usage of Volatile Fatty Acids Derived From Food Waste
Codigestion of Wastewater and Food Waste
Conclusions and Perspectives
References
Chapter-Fourteen---Food-Wast_2021_Current-Developments-in-Biotechnology-and-
Food Waste Policy
Introduction
European Perspectives
UK Food Waste Policy Development
France
Denmark
Italy
North America-US Federal Government, State and Canadian Food Waste Policy Initiatives
US Federal Government
USA State and Local Governments
Canada
Australia
Conclusions and Perspectives
References
Chapter-Fifteen---Life-Cycle-Assessment-an_2021_Current-Developments-in-Biot
Life-Cycle Assessment and Sustainability Aspects of Food Waste
Introduction
Sustainable Development Goals and the Waste Hierarchy
Managing Food Surplus and Food Waste
The LCA Methodology
Goal and Scope Definition
Goal
Functional Unit
Scope
Method to Calculate the Environmental Impacts
Allocation
Extending the System Boundaries
Inventory Analysis
Construct a Detailed Flow Chart
Collect Data for Each Process in the Detailed Flow Chart
Scale the Data to the Functional Unit
Impact Assessment
Interpretation
Simplified LCA
The Goal and Scope Definition
The Inventory Analysis
The Impact Assessment
The Interpretation
Environmental Perspectives of Different Waste Treatment Methods
Conclusions and Perspectives
Acknowledgments
References
Index_2021_Current-Developments-in-Biotechnology-and-Bioengineering
Index
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Citation preview

Current Developments in Biotechnology and Bioengineering

Series Editor

Ashok Pandey Distinguished Scientist, Centre for Innovation and Translational Research, CSIR-Indian Institute of Toxicology Research, Lucknow, India

Current Developments in Biotechnology and Bioengineering

Sustainable Food Waste Management: Resource Recovery and Treatment Edited by

Jonathan Wong Head and Professor, Department of Biology, Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong

Guneet Kaur Assistant Professor, Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong

Mohammad Taherzadeh Professor, Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden

Ashok Pandey Distinguished Scientist, Centre for Innovation and Translational Research, CSIR-Indian Institute of Toxicology Research, Lucknow, India

Katia Lasaridi Professor, School of Environment, Geography and Applied Economics, Harokopio University, Athens, Greece

Elsevier Radarweg 29, PO Box 211, 1000 AE Amsterdam, Netherlands The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States Copyright © 2021 Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library ISBN: 978-0-12-819148-4 For information on all Elsevier publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Susan Dennis Acquisitions Editor: Kostas Marinakis Editorial Project Manager: Andrea R. Dulberger Production Project Manager: Debasish Ghosh Cover Designer: Greg Harris Typeset by SPi Global, India

Contributors K. Abeliotis School of Environment, Geography and Applied Economics, Harokopio University, Athens, Greece Min Addy Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States Avanthi Althuri Bioengineering and Environmental Sciences Lab, CEEFF, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, India Jeyakumar Rajesh Banu Department of Life Sciences, Central University of Tamil Nadu, Neelakudi, Thiruvarur, Tamil Nadu, India E.M. Barampouti Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece Kim Bolton Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden Pedro Brancoli Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden Debkumar Chakraborty Bioengineering and Environmental Sciences Lab, CEEFF, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, India Sulogna Chatterjee Bioengineering and Environmental Sciences Lab, CEEFF, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, India Dongjie Chen Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States Paul Chen Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States xi

xii

Contributors

Pengfei Cheng Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, China Yanling Cheng Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; College of Biochemical Engineering, Beijing Union University, Beijing, China C. Chroni School of Environment, Geography and Applied Economics, Harokopio University, Athens, Greece Kirk Cobb Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States Jeff Cooper Former President of the Chartered Institution of Wastes Management and the International Solid Waste Management Association, Independent Environmental Consultant and Technical Writer, London, United Kingdom Mattias Eriksson Department of Energy and Technology, Swedish University of Agricultural Science, Uppsala, Sweden Shuhao Huo Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China Petchi Muthu K. Ilamathi Department of Plant Science, Manonmaniam Sundaranar University, Tirunelveli, Tamil Nadu, India Guneet Kaur Department of Biology; Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China Yukesh Khanna Environmental Engineering and Biotechnology Unit, Regional center of Anna University, Tirunelveli, Tamil Nadu, India Katia Lasaridi School of Environment, Geography and Applied Economics, Harokopio University, Athens, Greece

Contributors

xiii

Kun Li Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, School of Resources, Environmental and Chemical Engineering, Nanchang University, Nanchang, China Chao Liu College of Resources and Environment, Hunan Agricultural University, Changsha, Chinaa Junzhi Liu Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, China Yuhuan Liu State Key Laboratory of Food Science and Technology, Nanchang University, Jiangxi, China M. Loizidou Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece Lukitawesa Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden Liwen Luo Department of Biology; Sino-Forest Applied Research Centre for Pearl River Delta Environment, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China Yiwei Ma Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States S. Mai Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece D. Malamis Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece T. Manios School of Agricultural Science, Hellenic Mediterranean University, Crete, Greece

xiv

Contributors

S. Venkata Mohan Bioengineering and Environmental Sciences Lab, CEEFF, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, India K. Moustakas Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece Kumarasamy Murugesan Department of Environmental Science, Periyar University, Salem, Tamil Nadu, India V. Panaretou Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece Kowsalya Paramasivam Department of Environmental Science, Periyar University, Salem, Tamil Nadu, India Kamran Rousta Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden Roger Ruan Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States Charles Schiappacasse Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States Ammaiyappan Selvam Department of Biology; Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China; Department of Plant Science, Manonmaniam Sundaranar University,Tirunelveli, Tamil Nadu, India Kaarmukhilnilavan R. Srinivasan Department of Environmental Science, Periyar University, Salem, Tamil Nadu, India Yangyang Sun Department of Environmental & Low-Carbon Science, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, China Mohammad Taherzadeh Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden

Contributors

xv

Ch. Tsouti Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece Muthulingam Udayakumar Department of Plant Science, Manonmaniam Sundaranar University, Tirunelveli, Tamil Nadu, India Kristiadi Uisan Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China Steven Wainaina Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Sweden Gaihong Wang Bioenergy Research Institute, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China Lu Wang Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology, Shanghai, China Mengyao Wang Bioenergy Research Institute, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China Xuan Wang Department of Biology; Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China Yunpu Wang Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN, United States; State Key Laboratory of Food Science and Technology, Nanchang University, Jiangxi, China Jonathan Wong Department of Biology; Institute of Bioresources and Agriculture; Sino-Forest Applied Research Centre for Pearl River Delta Environment, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China

xvi

Contributors

Suyun Xu Department of Environmental & Low-Carbon Science, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, China Binghua Yan College of Resources and Environment, Hunan Agricultural University, Changsha, China Jiachao Zhang College of Resources and Environment, Hunan Agricultural University, Changsha, China Jun Zhou Bioenergy Research Institute, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China Peiru Zhu Bioenergy Research Institute, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China

Chapter | One

Sustainable Food Waste Management: An Introduction Guneet Kaura,b, Katia Lasaridic, and Jonathan Wonga,b Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinaa Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinab School of Environment, Geography and Applied Economics, Harokopio University, Athens, Greecec

1 INTRODUCTION Recent developments in agricultural practices have been successful to increase food production and cater to the growing demands of food availability to the increasing global population. However, this has also led to the generation of a staggering amount of wastes, which are termed as “food chain supply wastes” and arise during various steps of the supply chain including organic waste and packaging waste materials. On top of it, food waste is also generated through global economic development and consumerism [1]. Food waste is a global social, environmental, and economic problem that is attributed to the significant quantities of food waste generated per year. According to the Food and Agricultural Organization (FAO), this amounts to 1.3 billion tons, while one-third of the total food produced is wasted globally [2]. Food waste results from the decision of disposal of food that still has a residual nutrient value, which relates to the handling efficiency and behavior of retailers, food service sector, and consumers. A difference on the food waste generation pattern is usually observed between developed countries such as North America and Europe and less developed and low-income countries such as North Africa, West and Central Asia, South and Southeast Asia, and Latin America. In the former, significant food wastage is seen at the consumer stage, while wastes generated from early and middle stages of the supply chain, that is, food production, processing, and storage, are more common in the latter [3]. 1 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00001-4 Copyright © 2021 Elsevier Inc. All rights reserved.

2 Sustainable Food Waste Management: An Introduction While increasing quantities of food waste are being generated, landfilling remains the main disposal method. Landfilling of food waste is not a sustainable method due to the environmental issues of greenhouse gas (GHG) emission, odor generation, and leachate production with the latter leading to increasing risk of groundwater pollution [4]. Furthermore the scarcity of land in countries/cities like England, Singapore, and Hong Kong makes landfilling an undesirable option for waste management. Therefore more efficient, financially viable, and sustainable treatment and recovery technologies are urgently required [5]. The high biodegradability of food waste; its enormous energy, chemical, and material potential due to the residual functional molecules stored in it; its abundant and almost cost-free availability; and its amenability to various processing technologies make it a “valuable resource” rather than a “waste.” These factors along with the Sustainable Development Goals of food security, environmental protection, and material and energy efficiency are the key drivers of efficient and sustainable food waste management (Fig. 1). The possibility of treatment and transformation of food waste into valuable product streams depends on its availability, collection, chemical complexity, and suitability for individual treatment technologies. This requires a better understanding of food waste feedstocks in terms of their composition, volumes,

FIG. 1 Schematic of steps in food waste treatment for resource recovery.

2 Food Waste Generation and Collection

3

properties, possible conversion schemes, and evaluation of conventional and advance technologies from a sustainability perspective. This book discusses such aspects, addresses resource management and recovery, and provides an updated account of biochemical, chemical, and thermal/mechanical technologies for food waste treatment.

2 FOOD WASTE GENERATION AND COLLECTION Food waste is considered as a burden from an environmental perspective and results in depletion of water and land resources and increased GHG emissions, thereby negatively affecting the climate and natural habitats. At a global level the GHG emissions resulting from food waste are equivalent to 3.49 Gt CO2-eq [5], while the other significant impact is economical. For example, in the United States, the economic loss due to food being wasted reaches up to USD 198 billion every year. The maximum contribution to this amount is from the restaurants, catering, and domestic consumers (63%), while distribution and retail businesses contribute 37%. The United Nations 2030 Agenda for Sustainable Development Target 12.3 calls for a reduction of food waste along various steps of the supply chain and a 50% decrease of food waste per capita at the consumer and retail stages. Food waste constitutes a major fraction of the total municipal solid waste (MSW), for example, in a small metropolitan city like Hong Kong with only around 7.5 million people; food waste accounts for a significant 31% of MSW disposed at landfills every year [6]. The knowledge of the share and composition of food waste in the total MSW is a prerequisite for selection of appropriate method for its management [7]. The share of food waste across supply chain varies between developed and developing regions with more food being waste at retail and consumer level in the former and higher food waste resulting from processing stages in the latter. Food waste accounting forms the basis for food waste policy design related to reduction and prevention targets as well as treatment and recycling policies. The design of food waste management strategy depends on the contribution to food waste by various stages of supply chain, total amount of food wasted, and types of food wasted the most [8]. Both food waste composition and quantity govern the selection of appropriate treatment technologies. Furthermore the way food waste is collected from generators is another crucial step in the overall food waste management chain and greatly affects the food waste properties, which in turn affect the performance of downstream management operations. These properties can be divided into four main categories—physical, chemical, elemental, and bromatological. Majority of food waste is collected either by source separation systems or through mechanical separation of mixed MSW. Consequently, different collection pathways lead to different food waste properties. In terms of physical properties, due to the inherent heterogeneity of food waste, the particle size varies significantly, and the size differentiation is evident among individual fractions

4

Sustainable Food Waste Management: An Introduction

of food waste. Thus a requirement of pretreatment processes for size reduction and homogenization arises prior to downstream operations. Impurities in sorted food waste are important physical parameters that affect subsequent treatment and the end products’ quality. Food waste sorting by door-to-door collection appears to result in the segregated food waste with lesser amounts of nonbiodegradable materials (e.g., glass, metals, and plastics) as compared with road container collection. The presence of metals in food waste is also considered to negatively affect its valorization potential. According to Malamis et al., mixed food waste consistently contained higher concentrations of certain metals as compared with sorted food waste [9]. This is commonly related to the migration of metals into food waste fractions from materials such as batteries and ferrous metals that are commonly found in mixed wastes. Therefore the food waste collection method plays an important role for its management, and thus separate collection is a preferred method to obtain end products with acceptable quality for market uptake. Concerning the food waste separate collection scheme, there are six main factors that affect the scheme implementation and performance. These are legislation, food waste availability and expected yields, type and capacity of existing or future treatment facilities, area characteristics, political and social acceptability, and collection cost. Political commitment is found to be more important than availability of finance to develop sustainable food waste management systems. Finally, efficient monitoring is required to provide timely feedback on the efficiency of several components of food waste management scheme to allow redesign and improvement in implementation of different steps of the management scheme.

3 FOOD WASTE PREVENTION One of the most decisive steps to tackle food waste is to recognize it as an issue of great significance and concern. This is important to improve resource efficiency, and in fact, this has been the focus of EU countries since 2011 to reduce food losses along production and supply chain. Furthermore, in the Circular Economy Package launched in 2015, there is a commitment to halve the per capita food waste at retail and consumer level too. Under the Circular Economy and Industrial Symbiosis perspective, importance is given to processes that close the material loops, cascade used resources, discover new or secondary resources within waste, and drastically prevent waste generation [10]. In the waste management hierarchy, waste prevention is of higher priority followed by reuse, recycle, and material/energy recovery, and the lowest priority is disposal. Redistribution or donation of surplus food that would have otherwise gone to the waste stream appears to be an important means to prevent food waste generation and contribute to alleviate food insecurity. Charities and nonprofit organizations play key roles in the salvage and redistribution of food surplus to deprived people. Another important method of food waste prevention is through avoidable food losses based on esthetic demands of the

4 Food Waste Management and Treatment Technologies

5

market for fresh produce. These are largely driven by the reluctance of retailers and consumers to market and consume, respectively, the “ugly” or “wonky” fruits and vegetables that deviate from optimal esthetic standards of color, size, shape, and weight. To this end the initiatives and campaigns such as “Love Food Hate Waste” of the “Waste Resource Action Programme” (WRAP) in the United Kingdom and FLAW4LIFE project “Spreading Ugly Fruit Against Food Waste” in Portugal are some of the examples of public or private initiatives to combat this behavior [11]. Although being an important food waste prevention mechanism, the concerns over the safety of the offered items are often voiced. However, this can be alleviated with a good government policy and legal support.

4 FOOD WASTE MANAGEMENT AND TREATMENT TECHNOLOGIES Food waste prevention undoubtedly has the highest priority in food waste management hierarchy. However, it is a gradual process that is largely governed by social behavior rather than technological aspects, as discussed in Section 3. Therefore efficient food waste management technologies are needed to be developed to manage the increasing quantities of food wastes being generated.

4.1 Conventional Food Waste Management Technologies The conventional food waste management practices in decreasing order of added value of food waste include anaerobic digestion, composting, and animal feed. Upcycling of food waste as animal feed is regarded as the most convenient and cost-effective route for food waste, which can divert food waste from the waste stream. This can be accomplished either directly through the chemical or physical processing of food waste or indirectly through biological conversion such as black soldier fly larvae or microbial fermentation. Food waste source and its composition govern the selection of these methods. Contamination risks associated with feed from food waste have been restrained by regulatory frameworks and the requirement of proper processing methods such as heat treatment, drying, and pasteurization. To this end the variation in the composition and source of food waste hinders to some extent the standardization of the conversion processes and the final quality of the generated feed. However, the increasingly strict regulatory issues require a thorough evaluation before its application as animal feed. Besides, to produce quality fish feed from food waste is always a challenging task since the protein content in food waste is not high, which requires more research and development work to develop competitive fish feed products from food waste. The nature of coproducts generated in the process conversion of food waste to animal feed is an additional concern that limits this application. Another food waste treatment technology is composting, which is more environmentally acceptable as it diverts food waste from landfill by converting

6 Sustainable Food Waste Management: An Introduction organic matter into stabilized humus substance that can be used as a soil conditioner or organic fertilizer. It is usually used as land spread/injection and is a popular practice for food waste management that can be practiced either in large-scale centralized composting plants or in small community or home composters. The success of a composting process depends on the microbial decomposition that is governed by a number of factors including moisture content, carbon/nitrogen (C/N) ratio, and oxygen availability [12]. Under a suitable C/N ratio and good aeration, microorganisms in the composting mass undergo effective decomposition of organic matter with the generation of heat at thermophilic phase. This effectively kills pathogens, egg, and plant seeds to make the compost a safe organic soil conditioner. The major challenge of food waste composting is the high acidity generation during the storage and active composting stage since it causes inhibition of microbial growth, which can eventually cause composting failure [13]. Since food waste may contain high protein contents, the active ammonification process will lead to the loss of nitrogen in the form of ammonia gas. To conserve the nitrogen in compost is almost unavoidable in producing good quality compost from food waste. Thus optimization of composting process via addition of specific microbial consortia and precipitation of ammonia in the form of struvite are regarded as useful strategies to overcome composting challenges and make it a competent food waste treatment technology [14]. Controlling acidity and conserving nitrogen remain the key research challenges for food waste composting. With increasing focus on renewable energy, anaerobic digestion (AD) process has attracted increasing attention as an appropriate food waste treatment technology. Anaerobic digestion can degrade organic matter such as food waste via action of microorganisms in the absence of oxygen to produce renewable energy in the form of biomethane. It is a well-developed technology that is widely used in the wastewater treatment process for stabilization of sewage sludge, a major by-product resulting from the treatment of wastewater. Food waste contains a high organic matter with 20%–45% carbon and 80%–90% volatile solids and energy-rich compounds, for example, 10%–14% lipids and 5%–10% proteins. These characteristics provide it a high energy potential of 0.25KWh/kg and make it an interesting substrate for treatment by AD [15]. Countries and regions in the world such as Germany, China, United Kingdom, and Hong Kong have decided to adopt AD as the major biological treatment technology for recovering renewable energy from food waste. However, the composition of food waste is highly variable depending on its source. Furthermore problems of quick acidification due to rapid degradation of food waste, long retention time, and the presence of toxic inhibitors are critical factors that inhibit food waste AD process. While optimal physical, chemical, and operational factors such as pH, temperature, gas environment, and removal of inhibitors are required, the understanding of microbiota with microenvironment is becoming increasingly important to develop efficient AD process. Mechanically, various steps in AD are performed by different groups of microorganisms that interact with each other to create the optimal balanced conditions in the AD

4 Food Waste Management and Treatment Technologies

7

digester [16,17]. Such synergistic associations between different microbial groups are affected by changes in their microenvironment, which consequently affect overall AD performance. Therefore optimizing these interactions via improved digester design and increased knowledge of microbial growth and functional complexities is expected to allow efficient manipulation of AD conditions for improved food waste AD efficiency. Although the conventional technologies as described in this section are well developed and practiced for a long time, these technologies produce products (feed, compost, and biomethane) that are of lower economic value making them unsustainable without the subsidy from the governments. Therefore newer technologies that can have high value addition of food waste are increasingly being developed. These are discussed in the next sections.

4.2 Newer Food Waste Management Technologies The conversion of food waste to produce high-value products under the “wastebased biorefinery” scheme has attracted a great deal of attention in the recent years. Food waste is a suitable feedstock for such a biorefinery to produce valuable products such as biofuels, platform chemicals, fine/specialty chemicals, enzymes, and biomaterials. The most common routes for transformation of food waste include thermochemical processes such as gasification and pyrolysis and biochemical processes such as hydrolysis and chemical and biological conversions. Leading from AD the same technology can be employed for production of volatile fatty acids (VFAs) that contain up to six carbon atoms. These food waste-derived VFAs have a higher market value than biogas and offer substantial potential to be used as biobased building blocks in place of fossil fuel derivatives in various manufacturing sectors (e.g., chemical industry). For example, crude acetate has a market price of €600–800 per ton, which implies that the conversion of 1 kg of COD to acetate would earn €0.55–0.75. This is more than double the economic value of biogas. In fact, longer-chain fatty acids such as butyrate and caproate can reach even higher market prices [18]. VFAs are also useful substrates for production of polymers in subsequent bioconversions. For VFA production by AD process, pH is the most important factor influencing both VFA yields and type of VFA produced. Neutral and acidic conditions are reported to be more suitable for acidogenesis of food waste. Additionally, the metabolic pathways of acidogenic fermentation of food waste correspond to prevalence of different pH values. For example, pH 3.2–4.5 promotes lactic acid fermentation, while butyric acid production is more favorable at pH 4.7. pH 6 results in a mixed acid-type fermentation [19]. Thus regulation of microbial activity could be an important tool to overproduce the desired VFA spectrum in food waste acidogenesis. Microbial fermentation is another type of biobased conversion process for the production of valuable products from food waste, which employs bacteria, yeasts, and fungi under specific pH, temperature, and aerobic/anaerobic

8 Sustainable Food Waste Management: An Introduction conditions to produce biofuels (ethanol and butanol), platform chemicals (succinic acid and citric acid), fine chemicals (essential oils, biosurfactant, and bioadhesives), and biomaterials (composites, polymers, and bioplastics) [20]. These fermentation processes can be based on mono- or cocultures with more than one microorganism and utilize both agricultural-based and mixed food waste. Prior to fermentation, food waste might undergo specific pretreatment steps such as enzymatic and/or alkali hydrolysis to digest recalcitrant substances such as lignin and crystalline structure of cellulose to yield fermentable substrates. The design of various bioreactor configurations such as single stage or multistage, submerged or immobilized systems, and airlift reactors and nutrient feeding regimes such as fed-batch, continuous cultivations, and cell recycle systems allows efficient process development with high product yield and productivity. To this end, some studies on food waste valorization by fermentation have been conducted in laboratory-scale reactors; their successful demonstration at pilot scale would be an important step toward establishment of processes at large scale. While process parameter optimization can facilitate the production of high-value products through AD and/or microbial fermentation, their efficient separation and recovery from dilute fermentation broths is a major challenge. Furthermore, some of the processes experience product inhibition, for example, VFA and succinic acid, which results in limited volumetric productivities [21]. For this the use of in situ product recovery (ISPR) techniques has been attempted to remove the product as it is being formed in the reactor. Solvent extraction, adsorption, and membrane-based extractions (with or without solvent) have yielded promising results with improved productivities, product enrichment, and process intensification. Finally, in addition to biobased processes, pyrolysis and gasification have also been common methods to convert food waste into useful products such as biochar and biooil [22]. Biochar is a carbon-rich matrix that contains almost all the inorganic components present in the raw waste. It has a well-developed pore structure, specific surface area, stable aromatic structure, and abundant functional groups. It has wide applications in the energy and environment fields. Biopyrolytic oil from food waste largely contains acids, sugars, alcohols, ketones, aldehydes, phenols and their derivatives, furans, and other mixed oxygenates. Its heating value is approximately 15–20 MJ/kg. Reactor type, reaction rate, and food waste composition are the critical factors that govern the pyrolysis and gasification process and product properties. Optimization of process conditions has allowed significant progress, but key challenges remain including the control of pollutants arising in the process, specific products formed (i.e., biochar or biooil), and optimization of copyrolysis of food waste with other biomass feedstock to improve the desired product yield. The aforementioned food waste conversion technologies, their production processes, technical challenges, and products that can be obtained thereof are discussed in detail in this book. As described earlier in this chapter, the

References

9

development and implementation of such conversion technologies depend on food waste generation and availability, implementation of efficient food waste collection systems, the consequent food waste properties, and the suitability of food waste processing by various downstream operations. Therefore these aspects that lay the foundation of sustainable food waste management are discussed first in the book and are followed by food waste treatment technologies in the subsequent chapters.

5 CONCLUSIONS AND PERSPECTIVES Enormous quantity of food waste generated globally is a bioresource for the production of valuable products while also providing a means to lower the carbon footprint. Selection of a suitable food waste treatment technology is largely governed by food waste composition, quantity, and properties. These in turn can be mainly affected by the method adopted for food waste collection. Therefore a separate collection method with limited or no presence of contaminants such as metals, glass, and plastics is the most preferred one to allow obtaining products with acceptable quality for market uptake. Efficient food waste management by conversion to feed, compost, and biomethane includes some of the conventional and well-developed technologies for food waste treatment. However, the derived products are of low economic value and consequently sustainable with subsidy from the governments. The potential conversion of food waste to higher value products such as chemicals, materials, and advanced fuels via biological and thermochemical processes offers a new paradigm in economically sustainable food waste management and resource recovery. Increased research efforts toward development of optimal processes and government interest and encouragement of these newer technologies would be instrumental in realization of their benefits in the near future. The aforementioned aspects for development of a sustainable food waste management system are discussed in detail in the subsequent chapters of this book.

REFERENCES [1] FAO, Global Food Losses and Food Waste – Extent, Causes and Prevention, Rome, 2011. [2] A.S. Matharu, E.M. de Melo, J.A. Houghton, Opportunity for high value-added chemicals from food supply chain wastes, Bioresour. Technol. 215 (2016) 123–130. [3] J. Aschemann-Witzel, I. de Hooge, P. Amani, T. Bech-Larsen, M. Oostindjer, Consumerrelated food waste: causes and potential for action, Sustainability 7 (6) (2015) 6457–6477. [4] J.W.C. Wong, R.D. Tyagi, A. Pandey (Eds.), Current Developments in Biotechnology and Bioengineering: Solid Waste Management, Elsevier, Great Britain, 2017. [5] G. Kaur, L. Luo, J.W.C. Wong, Integrated food waste and sewage treatment – a better approach than conventional food waste-sludge co-digestion for higher energy recovery via anaerobic digestion, Bioresour. Technol. 289 (2019) 121698. [6] HKEPD, Monitoring of Solid Waste in Hong Kong: Waste Statistics for 2018, Hong Kong, 2018. [7] A. Hanc, P. Novak, M. Dvorak, J. Habart, P. Svehla, Composition and parameters of household bio-waste in four seasons, Waste Manag. 31 (7) (2011) 1450–1460.

10

Sustainable Food Waste Management: An Introduction

[8] C. Priefer, J. J€ orissen, K.-R. Br€autigam, Food waste prevention in Europe – a causedriven approach to identify the most relevant leverage points for action, Resour. Conserv. Recycl. 109 (2016) 155–165. [9] D. Malamis, K. Moustakas, A. Bourka, K. Valta, C. Papadaskalopoulou, V. Panaretou, O. Skiadi, A. Sotiropoulos, Compositional analysis of biowaste from study sites in greek municipalities, Waste Biomass Valoriz. 6 (5) (2015) 637–646. [10] K. Esbensen, C. Velis, Transition to circular economy requires reliable statistical quantification and control of uncertainty and variability in waste, Waste Manag. Res. 34 (2016) 1197–1200. [11] WRAP (Waste and Resource Action Programme) UK, Household Food and Drink Waste in the UK, http://www.wrap.org.uk/sites/files/wrap/Household_food_and_drink_waste_ in_the_UK_-_report.pdf, 2009. (Accessed 18 December 2019). [12] M.K. Awasthi, A. Selvam, K.M. Lai, J.W.C. Wong, Critical evaluation of postconsumption food waste composting employing thermophilic bacterial consortium, Bioresour. Technol. 245 (2017) 665–672. [13] H.N.B. Cheung, G.H. Huang, H. Yu, Microbial-growth inhibition during composting of food waste: effects of organic acids, Bioresour. Technol. 101 (2010) 5925–5934. [14] X. Wang, A. Selvam, S.S.S. Lau, J.W.C. Wong, Influence of lime and struvite on microbial community succession and odour emission during food waste composting, Bioresour. Technol. 247 (2018) 652–659. [15] P.K. Obulisamy, D. Chakraborty, A. Selvam, J.W.C. Wong, Anaerobic co-digestion of food waste and chemically enhanced primary-treated sludge under mesophilic and thermophilic conditions, Environ. Technol. 37 (2016) 3200–3207. [16] J.Z. Li, Q.Y. Ban, L.G. Zhang, A.K. Jha, Syntrophic propionate degradation in anaerobic digestion: a review, Int. J. Agric. Biol. 14 (2012) 843–850. [17] L. Luo, G. Kaur, J.W.C. Wong, A mini-review on the metabolic pathways of food waste two-phase anaerobic digestion system, Waste Manag. Res. 37 (2019) 333–346. [18] R. Kleerebezem, B. Joosse, R. Rozendal, M.C.M. Van Loosdrecht, Anaerobic digestion without biogas? Rev. Environ. Sci. Biotechnol. 14 (2015) 787–801. [19] Y. Wu, C. Wang, M. Zheng, J. Zuo, J. Wu, K. Wang, B. Yang, Effect of pH on ethanoltype acidogenic fermentation of fruit and vegetable waste, Waste Manag. 60 (2017) 158–163. [20] K.L. Ong, G. Kaur, N. Pensupa, K. Uisan, C.S.K. Lin, Trends in food waste valorization for the production of chemicals, materials and fuels: case study south and Southeast Asia, Bioresour. Technol. 248 (2018) 100–112. [21] S. Wainaina, M. Parchami, A. Mahboubi, I.S. Horva´th, M.J. Taherzadeh, Food wastederived volatile fatty acids platform using an immersed membrane bioreactor, Bioresour. Technol. 274 (2019) 329–334. [22] Y.J. Tang, Q.X. Huang, K. Sun, Y. Chi, J.H. Yan, Co-pyrolysis characteristics and kinetic analysis of organic food waste and plastic, Bioresour. Technol. 249 (2018) 16–23.

Chapter | Two

Food Waste Properties Ammaiyappan Selvama, Petchi Muthu K. Ilamathia, Muthulingam Udayakumara, Kumarasamy Murugesanb, Jeyakumar Rajesh Banuc, Yukesh Khannad, and Jonathan Wonge,f Department of Plant Science, Manonmaniam Sundaranar University, Tirunelveli, Tamil Nadu, Indiaa Department of Environmental Science, Periyar University, Salem, Tamil Nadu, Indiab Department of Life Sciences, Central University of Tamil Nadu, Neelakudi, Thiruvarur, Tamil Nadu, Indiac Environmental Engineering and Biotechnology Unit, Regional center of Anna University, Tirunelveli, Tamil Nadu, Indiad Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinae Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinaf

1 INTRODUCTION Trends in economic and population growth pose huge pressure on our natural resources. Globally, about 2.01 billion tonnes of solid waste was produced in 2016 and is predicted to be around 3.4 billion tonnes by 2050 [1]. Due to rapid urbanization and industrial development around the world, the steady increase in waste generation has put pressure on governments to handle the diverse nature of waste. Waste is a major global issue and managing it requires a significant fraction of the budget in every country, which eventually threatens social and economic development. For example, by 2025, an estimated increase of about 83% in the annual budget, when compared with the budget in 2012, will be needed to cope with the predicted increase of 69% in the quantity of waste. Especially, this increase is predicted to be more than fourfold to fivefold in lowincome and lower-middle-income countries due to current inadequate waste management practices that necessitate efficient practices in the future [1,2]. In the context of sustainability, waste is considered as a measure of inefficiency, while waste avoidance is considered as a sustainable practice; thus waste prevention has received increased attention recently. Nevertheless, considering the fact that the generation of waste is inevitable, a sustainable way of recycling waste should have equal priority in waste management systems [2]. 11 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00002-6 Copyright © 2021 Elsevier Inc. All rights reserved.

12

Food Waste Properties

Waste can be categorized into a number of fractions based on its origin, of which municipal solid waste (MSW) is a key fraction posing challenges to governments because of the volume generated, heterogeneity, and requirement of an array of techniques to sort it before treatment and disposal. When considering the composition of MSW, the organic or putrescible fraction represents more than 50% in upper-middle-, lower-middle-, and low-income countries, while it is 32% in high-income countries [1]. In high-income countries, the amount of organic waste is comparable to that of other regions, e.g., developing countries, in absolute terms but because of the larger amounts of packaging waste and other nonorganic waste, the fraction of putrescible waste is less. On average, 44% of MSW is putrescible on a global basis indicating that one-half of the waste is biodegradable and should be recycled properly to avoid/minimize its impact on the environment.

2 FOOD LOSSES AND FOOD WASTE Nearly one-third of all food produced for human consumption, amounting to 1.3 billion tons and US$1 trillion per year, is lost or wasted across the food supply chain. However, this monetary value of wasted food does not account for environmental and social costs of the wastage borne by society at large. If social and environmental costs are included, then food loss would cost about US$2.6 trillion annually [3,4]. Industrialized and developing countries dissipate roughly the same quantities of food—670 and 630 million tonnes, respectively [4].

2.1 Definition The definitions of “food waste” and “food loss” within the supply chain have been a subject of disagreement among scientists [5]. It is necessary to distinguish food loss and food waste to have a clear understanding of the content to be discussed in this chapter. Food loss can be defined as the “decrease in quantity or quality of food, caused mainly by food production and supply system functioning or its institutional and legal framework” [6]. Food waste can be defined as “any food, and inedible parts of food, removed from (lost to or diverted from) the food supply chain, by choice, or which has been left to spoil or expire as a result of negligence by the actor—predominantly, but not exclusively the final consumer at household level” [6]. Food loss and food waste can occur at every stage of the food supply chain. Thus food waste is an inevitable component of food loss. Food wastage encompasses both food loss and waste, thus including any food lost by deterioration or removal [7].

2.2 Sources and Quantities of Food Waste The main stages of food loss in the food supply chain include production, handling and storage, processing and packaging, distribution and marketing, and consumption [8]. Food wastage is generated all along the supply chain, from the agricultural production stage to final consumption (Table 1). Of this, upstream stages, including production, and postharvest handling and storage

2 Food Losses and Food Waste

13

TABLE 1 Food Wastage Occurring During Different Stages of the Food Supply Chain [8, 64]. Stage

Definition

Examples

Production

Losses occurring during harvesting

Edible crops left in field; losses due to mechanical damage, spilling during harvesting

Handling and storage

Losses occurring after the product leaves the farm for storage or transport

Losses due to pathogens and pests; poor infrastructure of transport; spillage during handling and storage

Process and packaging

Losses occurring during processing, product evaluation, and packaging

Contamination during processing; removal of items as part of grading; inadequate packaging technologies resulting in spillage of products

Distribution and market

Losses occurring during distribution to markets and commercial marketing, including wholesale and retail

Poor infrastructure of cold storage, including during transportation causing spoilage; overproduction due to errors in demand forecast exceeding the internal sell-by date; product returns due to package damage; poor handling in markets

Consumption

Losses occurring in households at the consumer level

Buying more than needed; exceeding useby/best-before date; spoilage during storage

represent 54% of total wastage, while downstream stages, including processing, distribution, and consumption, represent 46%. Among these two categories, food waste is generated through the downstream stages [7]. About 46% of 1.3 billion tonnes, amounting to 598 million tonnes of food waste (excluding food loss), are generated each year. Comparatively, food is wasted at the consumer level to a great extent in medium- and high-income countries compared with low-income countries (Fig. 1). The per capita food wasted by consumers in Europe and North America is 95–115 kg/year, while this figure in sub-Saharan Africa and South/Southeast Asia is only 6–11 kg/year [9]. In contrast, in lowincome countries, food loss occurs at 40% mainly due to technical limitations in harvesting techniques, storage and cooling facilities in difficult climatic conditions, infrastructure, packaging, and marketing systems. About 44% of MSW generated are organic or putrescible waste (food and green wastes) that were calculated to be around 935 million tonnes/year in 2016. Two highly populated countries, China and India, top the list with organic waste generation of about 129 and 89 million tonnes/year representing 13.75% and 9.55% of global organic waste generation, respectively, in 2016 [1,10]. Since this organic fraction mainly contains food waste, it is conceivable that either more food is wasted at the retailer and consumer levels or the estimated food

14 Food Waste Properties Production

61

46

52

Handling and storage

34

Processing

28

Distribution and market

13 15

17 18

4 37

Consumption

5 13 7 37

6 11 7

2 23

9

North America and Oceania 42%

5 12

4 21

22 39 28

6 17

9

23

32

23

17

Industrialized Asia 25%

Europe

22%

North Africa, West and Central Asia 19%

Latin America

South and Southeast Asia

Sub-Saharan Africa

15%

17%

23%

Share of total food available that is lost or wasted

FIG. 1 Food lost or wasted by region and stage in the food supply chain, 2009. Percent of kcal lost and wasted. Number may not sum to 100 due to rounding. Adapted from B. Lipinski, C. Hanson, J. Lomax, L. Kitinoja, R. Waite, T. Searchinger, 2013. Reducing Food Loss and Waste. Working Paper, World Resources Institute (WRI), Washington, DC, USA, p. 39.

waste from the downstream processing stages of the food supply chain could be seriously underestimated. For example, a study by the Institution of Mechanical Engineers indicated that food loss can be up to 2 billion tonnes [11]. Food wastage from different stages of the food supply chain, especially from the downstream processes, is a potential source for recycling [12]. Food loss and food waste occur throughout the food supply chain. The waste generated during the retail and consumer levels often ends up as MSW if properly collected. However, food waste generated at the industrial level during processing could be used in other industries for the generation of value-added products and would not reach the MSW stream completely. The waste produced in industries is concentrated and more homogeneous than the putrescible waste from MSW, thus it could be a target for biorefinery processes. The quantities of some of the waste generated through different food supply chains are presented in Table 2. An array of waste products is produced from food processing industries. Olive mill residues appear to be the single largest industrial residue with a quantity of about 30 million tonnes per year [13], followed by waste orange peel after juicing and citrus bagasse representing more than 20 million tonnes generated from the European Union, Brazil, South Africa, and China [14–16]. Although not considered as food waste, enormous quantities of plant biomass residues, including rice straw, wheat straw, oat straw, barley straw, corn stover, and rice husk, are produced each year mainly during the harvesting stage. Considering the quantity of these wastes, a renewed interest in these feedstocks for various biological treatments is under way.

2 Food Losses and Food Waste

15

TABLE 2 Quantities of Food Waste and Losses Reported in the Literature. Waste From FSW

Volume Available (tonnes/year)

Location

References

Europe Olive mill residue

30,000,000

Mediterranean basin

[13]

Waste orange peel

607,500

EU 27

[15]

Cassava bran

4,214,000

Brazil

[16]

Corn cob

12,983,000

Brazil

[16]

Coconut husk

481,000

Brazil

[16]

Citrus bagasse, peel, and seeds

10,384,000

Brazil

[16]

Waste orange peel

7,752,000

Brazil

[15]

Waste orange peel

560,000

Mexico

[15]

Waste orange peel

2,947,500

USA

[15]

Maize germ and wraps

11,802,000

Brazil

[16]

Maize straw, stems, and leaves

46,029,000

Brazil

[16]

Grape pomace

122,000 (dry basis)

California

[65]

Rice hulls and cotton gin trash

450,000

California

[65]

Wheat bran

1,354,000

Brazil

[16]

Vegetable crop residue

1,000,000 (dry basis)

California

[65]

Nutshell and pits

400,000

California

[65]

Orange peel (postjuicing)

139,724

South Africa

[15]

Cocoa pods

20,000,000

Ivory Coast

[15]

Cashew shell nut liquid

20,000

Tanzania

[66]

Cashew shell nut

60,000

Tanzania

[67]

Palm shells (from palm oil production)

4,300,000

Malaysia

[68]

Waste orange peel

90,000

China

[15]

Apple pomace

3,000,000–4,200,000

Global

[14]

Grape processing waste

5,000,000–9,000,000

Global

[14]

Citrus fruit processing residues

15,600,000

Global

[14]

America

Africa

Asia

World

(Continued )

16

Food Waste Properties

TABLE 2 Quantities of Food Waste and Losses Reported in the Literature—cont’d Waste From FSW

Volume Available (tonnes/year)

Location

References

Banana processing

9,000,000

Global

[14]

Tomato pomace

600,000–2,000,000

Global

[69]

Corn stover

203,620,000

Global

[70]

Rapeseed meal

35,000,000

Global

[71]

Sunflower meal

14,900,000

Global

[71]

Rice husk

196,000,000

Global

[72, 73]

Rice straw

731,340,000

Global

[70]

Wheat straw

354,340,000

Global

[70]

Oat straw

10,620,000

Global

[70]

Barley straw

58,450,000

Global

[70]

Pea and broad bean by-products

8,000,000

Global

[74]

3 PROPERTIES OF FOOD WASTE Food waste is the largest fraction of waste reaching landfill. Once landfilled, degradation, especially anaerobic, contributes to greenhouse gas emission and global warming. In addition, the key nutrients present in organic matter are also locked up consequently increasing our dependence on finite virgin sources of fertilizers. Apart from these two issues, currently, demand for energy is increasing due to the increasing population and industrial activities throughout the world, while the scarcity and/or high price of conventional energy resources critically poses socioeconomic constraints resulting in the identification of renewable energy resources. Food waste has become an attractive alternative feedstock for energy production over the last two decades. Waste is a major issue requiring efficient and expensive management, while its use for the production of value-added products converts a problem into a profit center and creates a win–win situation at both ends. The use of food waste as a feedstock for industrial applications such as energy production, biomass production, and the recent biorefinery applications is often challenged by the properties of the available food waste. Current major uses of food wastes as a substrate include: (1) animal feed, (2) composting, (3) anaerobic digestion, (4) synthesis of novel chemicals, and (5) incineration. However, its heterogeneous nature is one of the critical problems of using food waste as a resource for such applications, which requires a thorough analysis of its physicochemical properties. This chapter analyzes the properties of food waste and its implications on different treatment technologies.

4 Proximate Analysis

17

4 PROXIMATE ANALYSIS Proximate analysis focuses on determining the fraction of the material that burns in a gaseous state (volatile solids, VS), in a solid state (fixed carbon), and the fraction of inorganic residues (ash) and is considered to be a fundamental tool for biomass energy calculations [17]. In addition, water (moisture) content is an important property affecting the suitability of food wastes in different treatment technologies. Volatile matter (VS) or organic matter is a measure of the available organic content, the energy source for microbes in biological treatment technologies. Moisture content, total solids (TS), VS, and VS/TS contents of food waste reported in the literature are presented in Table 3. The moisture content of food waste ranges from 48% to 95% depending on the source and nature of the waste with an average value of 77%. Generally, source-segregated food waste (SSFW), organic fraction of MSW (OFMSW), and samples from households have a moisture contents of around 70%, while food waste from canteens and restaurants has a moisture content of 75%–85%. Disposal of part of the water served in restaurants along with food waste may have caused this higher moisture content. Occasionally, a few samples were reported to contain more than 90% of water in the waste [18–20]. This high moisture content of food waste indeed affects its applicability to mass burn technologies such as incineration in which high-volume reduction is possible in a shorter time. Alternatively, food waste has to be mixed with other materials to overcome the high moisture content or to include a pretreatment to eliminate the moisture to less than 50% [21] before incinerating the waste. Food waste as a feedstock for composting has gained momentum over the last decade. Despite the popularity of the composting process, food waste as a substrate has a number of challenges because of its unique properties [22]. Structurally, the high moisture of food waste necessitates a large volume of bulking agents that should also adjust the low carbon to nitrogen (C/N) ratio to an optimum level required for composting. Bulk density of the material has a positive relationship with the moisture content of the samples. In most of the reports, bulk density is not reported and the available result indicates that bulk density could range from 505 to 860 kg/m3 [22–24]. Bulk density affects the pore space in the substrate, thus critically influencing the composting process rather than the other treatment technologies. The fraction that remains after removing the water is the TS or dry matter content, thus it has an inverse relationship with the moisture content. The TS content ranges from 5.4% to 51.5% with an average of about 22.3%. VS content ranges from 73% to 98% with an average value of about 91.6%. It is the characteristic nature of food waste to contain a high fraction of VS when compared with other types of organic wastes (Table 3). Previous reviews of food waste properties reported VS/TS values of 88.2  8.2% [25] and 80%–97% [26,27]. SSFW, OFMSW [28], and a few samples from households [29] and canteens [18] were reported to have a VS content of less than 90%, probably related to the contamination of food waste with other materials. Esteves and

18

Food Waste Properties

TABLE 3 Moisture Content, Total Solids, and Volatile Solids Contents of Food Waste Reported in the Literature. Food Waste Sourced Froma

Country

Moisture Content (%)

TS or DM (%)a

VS or OM (%)a

VS/TS (%)

References

73.4

[75]

Shopping mall and food market

Australia, Sydney

Household

Brazil, Salvador

87.5

Canteen

China, Hangzhou

80.4

19.6

17.8

Canteenb

China

75.3–83.3b

16.7–24.7b

16.4–23.5b 95.1–98.2b [78]

Kitchen

China, Beijing

66.9

33.1

Cafeteria

China, Beijing

77.3

22.6

17.9

79.2

[18]

FVW— cafeteria

China, Beijing

90.5

9.5

7.9

83.4

[18]

University restaurant

China, Beijing

78.3

21.8

20.1

92.2

[79]

Cafeteria

China, Beijing

81.1

18.9

17.5

93.0

[43]

Dining hall

China, Beijing

88.12

13.68

13

95.0

[80]

Canteen

China, Beijing

80.0

20.1

19.2

95.8

[81]

Canteen

China, Beijing

76.9

23.1

21

90.9

[82]

Dining hall

China, Beijing

78.7

21.3

17.0

79.9

[83]

University restaurant

China, Dalian

76.25

23.75

21.18

89.2

[84]

University restaurant

China, Dalian

76.8

23.2

21.7

93.5

[85]

University restaurant

China, Dalian

74.9

25.1

20.77

82.7

[86]

SFW

China, Hangzhou

74.3

25.7

25.2

98.2

[87]

Canteen

China, Jiangnan

75.13

24.87

23.87

95.98

[88]

Canteen

China, Nanning

76.72

23.28

21.2

91.26

[89]

[76] 90.8

[77]

[24]

4 Proximate Analysis

19

TABLE 3 Moisture Content, Total Solids, and Volatile Solids Contents of Food Waste Reported in the Literature—cont’d Food Waste Sourced Froma

Country

Moisture Content (%)

TS or DM (%)a

VS or OM (%)a

VS/TS (%)

References

Canteen

China, Shenzhen

81.6

18.4

17.5

95.2

[90]

Canteen

China, Xi’an

80

20

19.2

96.4

[91]

KW—canteen China, Yangling

76.8

23.2

22.2

95.69

[92]

Canteen

Denmark, Lyngby

84

16

14.9

93.41

[93]

SSFW

Finland, Forssa

73.0

27.0

24.91

92.26

[28]

SFW

Hong Kong

60

40

39.2

98.0

[46]

Household

Hong Kong

78

22

20.5

93.0

[94]

SFW

Hong Kong

84

16

14.6

91.0

[94]

Canteen

India, Assam

75.4

24.6

20.3

82.5

[95]

Household

India, Mumbai

62.1–66.2c

93.0

[96]

Canteen

Ireland

70.6

29.4

28.0

95.3

[97]

Household

Ireland

60.1

39.9

29.5

73.9

[29]

SFW

Italy

76.5

23.5

c

Cafeteria

Roma, Italy

Cooked KW

Italy, Rome

FVW

22.1 c

93.9 c

[61] c

13.0–15.5

12.0–15.0 95.0–97.0 [98]

76.3

23.7

22.5

95.0

[20]

Italy, Rome

94.6

5.4

4.5

83.0

[20]

OFMSW

Italy, Rome

66.6

33.4

29.7

89.0

[20]

SSFW

Italy, Treviso

72.5

27.5

23.6

86.6

[28]

Cafeteria

Japan, Tsukuba

75.9

24.1

Cafeteria

Korea, Daejeon

87.0

13.0

12.0

92.3

[100]

Cafeteria

Korea, Daejeon

82.9

17.1

16

93.6

[101]

[99]

(Continued )

20

Food Waste Properties

TABLE 3 Moisture Content, Total Solids, and Volatile Solids Contents of Food Waste Reported in the Literature—cont’d Food Waste Sourced Froma

Country

Korean restaurant

Moisture Content (%)

TS or DM (%)a

VS or OM (%)a

VS/TS (%)

References

Korea, Yongin

81.9

18.1

17.1

94.0

[102]

Canteen

KSA, Jeddah

77.5

22.5

19.4

86.1

[103]

Restaurant

Malaysia, Cameron Highlands

58.2

41.8

Food waste

Norway

82.2

17.8

16.1

90.0

[105]

Cafeteria

Pakistan

72.6

27.5

25.3

92.0

[106]

SSFW

Portugal, Lisbon

66.2

33.8

27.6

81.7

[28]

OFMSW from mechanical biological treatment plant

Spain, Barcelona

71.0

29.0

22.3

77.0

[107]

SSFW

UK, Eastleigh

74.1

25.9

24.0

92.7

[28]

SSFW

UK, Hackney

74.3

25.7

23.5

91.2

[28]

SSFW

UK, Ludlow

76.3

23.7

21.7

91.4

[28]

SSFW

UK, Luton

76.3

23.7

21.8

91.3

[28]

SFW (military rations)d

USA

48.5

51.5

49.1

95.3

[108]

Buffet leftovers at a casino

USA, Central NY

72.8

27.3

25.1

92.1

[109]

Grocery store

USA, Raleigh

87.1

12.9

12.2

94.2

[110]

Dining hall

USA, Raleigh

77.1

22.9

21.6

94.3

[110]

Hotel and conference center

USA, Raleigh

72.7

27.3

26.2

96.1

[110]

Restaurant

USA, Raleigh

84.5

15.5

14.1

90.9

[110]

[104]

4 Proximate Analysis

21

TABLE 3 Moisture Content, Total Solids, and Volatile Solids Contents of Food Waste Reported in the Literature—cont’d Food Waste Sourced Froma

Country

FWe

Global

Average (SD) values

Moisture Content (%)

TS or DM (%)a

VS or OM (%)a

22.8 (10.0) 77.0 (7.8)

23.2 (7.7)

20.8 (6.7)

VS/TS (%)

References

88.2 (8.2)

[25]

91.6 (5.8)

a

DM, dry matter; FVW, fruit and vegetable waste; FW, food waste; KW, kitchen waste; OFMSW, organic fraction of municipal solid waste; OM, organic matter, SFW, simulated food waste; SSFW, source-segregated food waste; TS, total solids; VS, volatile solids. b Range of values of 12 samples. c Range of values of two samples. d FW mimics transportable, calorie-dense military rations. e Average (SD) of 102 samples from 70 studies.

Devlin [30] analyzed the food waste collected from Welsh Local Authorities and reported higher TS and VS contents for samples collected during the winter season compared with samples collected during the summer season due to the seasonal variation in diets. In addition, reduced home composting during the winter season could also drive more organic waste toward MSW collection. However, in tropical countries, such a difference in diets that influence the VS may not exist, and a fairly uniform range of values can be expected throughout the year barring festive seasons. A high VS content of food waste is favorable for its utilization in composting, anaerobic digestion, and other biological technologies as well as incineration. However, a high moisture content of 90% will lose saprophytic value during incineration. For example, the calorific value of dry vegetable food waste was reported to be 19,230 kJ/kg, while that of as-received wet waste was 4170 kJ/kg [31], indicating the impact of moisture on energy recovery. This would favor the suitability of food waste to anaerobic digestion and other biorefinery approaches, while it would hinder the application of composting and incineration technologies. For composting, high moisture is an issue because large quantities of bulking agents are required to adjust the moisture levels to 50%–60%. However, as presented in Table 2, a large quantity of plant residues is generated especially during the harvesting and processing stages of cereals with very low moisture content in some countries, and are useful as bulking agents. Anaerobic digestion of organic materials involves a series of complex reactions in which each group of organisms involved in stages such as hydrolysis, acidogenesis, acetogenesis, and methanogenesis has different optimum environmental conditions. Thus a delicate balance must be maintained when all the reactions take place in a single chamber like a single-phase anaerobic digestion reactor. To avoid instability and achieve a steady rate of degradation,

22

Food Waste Properties

the VS content must be streamlined in the feed to more or less similar concentrations as well as controlling other factors such as pH and temperature.

5 CHEMICAL PROPERTIES The chemical properties of food waste, including pH, electrical conductivity (EC), and chemical oxygen demand (COD), critically affect the rate of its utilization by microbes. The pH indicates the acidity or alkalinity of the substrate, while the EC refers to the available salt content affecting the osmotic concentration of the liquid fraction available for microbes. Depending upon the types of treatments, specific pH needs to be maintained to cater for the specific microbes involved. For example, microbes involved in composting require a neutral pH, while other pH ranges could be deleterious, thus reducing the composting efficiency. The pH of food waste ranges from 3.9 to 6.7 with an average value of 4.9 (Table 4). Comparatively, food waste has an acidic pH compared to other organic wastes such as animal manure, blood meal, green waste, and sewage sludge [32–38]. In contrast to pH, many of the studies do not report the EC and a few available reports indicate that the average EC of food waste is around 1.9 mS/cm. Both pH and EC are relevant parameters for assessing the suitability of material for composting and anaerobic digestion. During composting, pH plays a crucial role in affecting the rate of stabilization because the low pH will inhibit the composting microbes [22, 39]. A comprehensive review of the impact of acidity on the composting process is presented in Chapter 5 of this book [40]. For anaerobic digestion, pH is one of the most influential parameters due to the different levels of sensitivity toward pH for different groups of organisms [41]. Among the different groups, pH tolerance of acidogens ranges from 4.0 to 8.5; however, most methanogens require a narrow window with a pH value between 6.5 and 7.2, beyond which methanogenesis fails. A pH of 7.0–8.0 is ideal for protein degradation, while 6.0–9.0 is ideal for carbohydrate degradation [42]. Considering the low pH of food waste, in a single-phase reactor, retaining the buffering agents is a prime concern to avoid the pH of the food waste inhibiting the methanogens. COD is another measure of available organic matter and a key parameter used in anaerobic digestion. During anaerobic digestion, the COD value is often used to determine the quantity of feed to the reactor. In addition, COD of the influent and effluent materials is used to calculate digestion efficiency. In the literature, based on the types of reactors and operation, both total COD (TCOD) and soluble COD (SCOD) values were reported in which the SCOD is the fraction readily available for microbes. The reported TCOD of food waste ranges from 868 to 1522 mg/g on a dry weight basis with an average value of 1253  151 mg/g dry food waste (Table 4). Of these the soluble fraction (SCOD) ranges from 58 to 1085 mg/g dry food waste. The average value of SCOD/TCOD was about 35.1%, while occasionally a value as high as 85% SOCD/TCOD was also reported [43] for cafeteria food waste that could probably be linked to the dominance of cooked food in the analyzed food

TABLE 4 pH, Electrical Conductivity (EC), and Chemical Oxygen Demand (COD) Values of Food Waste Reported in the Literature. Food Waste Sourced Froma

EC (mS/cm)a

Country pH

Total COD (mg/ g, dry basis)a

Soluble COD (mg/g, dry basis)

References

Household

Brazil, Salvador

5.4

[76]

Kitchen

China, Beijing

4.2

[24]

University restaurant

China, Beijing

4.8

1141

Cafeteria

China, Beijing

5.2

1275

Dining hall

China, Beijing

University restaurant

China, Dalian

5.7

University restaurant

China, Dalian

4.4

1310

668

[85]

University restaurant

China, Dalian

4.6

1408

647

[86]

SFW

China, Hangzhou

1110

342

[87]

Canteen

China, Xi’an

4.5

1290

360

[91]

KW— canteen

China, Yangling

4.2

[92]

SSFW

Finland, Forssa

5.7

[28]

Household

Hong Kong 5.33

1360

[94]

SFW

Hong Kong

1440

[94]

Canteen

India, Assam

5.02

Household

India, Mumbai

4.7–5.0b

Canteen

Ireland

4.1

Ireland

4.24

Household c

[79] 1085

[43]

434

[80] [84]

319

[95]

2.1–2.6b

[96] [29] 1281

b

401 b

[29] b

Cafeteria

Roma, Italy

4.8–5.5

1178–1285

285–500

[98]

Cooked KW

Italy, Rome

4.6

1377

254

[20]

FVW

Italy, Rome

4.7

1196

457

[20] (Continued )

24

Food Waste Properties

TABLE 4 pH, Electrical Conductivity (EC), and Chemical Oxygen Demand (COD) Values of Food Waste Reported in the Literature—cont’d Food Waste Sourced Froma

Country pH

EC (mS/cm)a

Total COD (mg/ g, dry basis)a

Soluble COD (mg/g, dry basis)

References

1048

263

[20]

OFMSW

Italy, Rome

4.7

SSFW

Italy, Treviso

6.16

Cafeteria

Korea, Daejeon

4.9

1154

285

[100]

Cafeteria

Korea, Daejeon

4.3

1146

58

[101]

Korean restaurant

Korea, Yongin

6.5

1318

589

[102]

Canteen

KSA, Jeddah

6.7

Restaurant

Malaysia, Cameron Highlands

4.68

Food waste

Norway

3.9

SSFW

UK, Eastleigh

5.02

[28]

SSFW

UK, Hackney

5.18

[28]

SSFW

UK, Ludlow

4.71

[28]

SSFW

UK, Luton

5.12

[28]

SFW (military rations)c

USA

Buffet leftovers at a casino

USA, 4.8 Central NY

FWd

Global

Average (SD) values a

[28]

0.9

[103] [104]

1522

534

1359

[108]

[109]

5.1 (0.7)d 4.9 (0.7)

[105]

868 (390)d 1.9 (0.9)

1253 (151)

[25] 440 (229)

DM, Dry matter; FVW, fruit and vegetable waste; FW, food waste; KW, kitchen waste; OFMSW, organic fraction of municipal solid waste; OM, organic matter, SFW, simulated food waste; SSFW, source-segregated food waste; TS, total solids; VS, volatile solids. b Range of values of two samples. c FW mimics transportable, calorie-dense military rations. d Average (SD) of 102 samples from 70 studies.

6 Nutrient Properties

25

waste. When the soluble fraction is high, it tends to have a high rate of acidification (acidogenesis) during anaerobic digestion that would reduce the feeding rate, especially in single-phase reactors. Otherwise, the high organic acid production rate will acidify the reactor and inhibit the methanogenesis. A two-phase approach that separates acidogenesis from methanogenesis is an ideal approach to avoid this situation and has gained popularity in recent decades [44–51].

6 NUTRIENT PROPERTIES Values of VS and COD are indicative of the available nutrition for the prevailing microbes; however, the ratio between specific nutrients is of importance in determining the efficiency of the applied technology. For example, a C/N ratio of 30 is considered to be ideal for the initial phase of composting. Therefore the concentration of specific nutrients such as carbon (C), nitrogen (N), phosphorus (P), potassium (K), etc., are being analyzed and reported in the literature. Total organic carbon (TOC), total Kjeldahl nitrogen (TKN), ammonium nitrogen (NH+4-N), total phosphorus (TP), total potassium (TK), and C/N values of food waste reported in the literature are presented in Table 5. In the literature, both TOC and total carbon as well as TKN and total nitrogen were used ambiguously at times and the values reported as TOC and TKN alone were considered, while the values obtained from the elemental analysis were not used in this compilation. The TOC values of food waste ranged from 29.7% in fruit and vegetable waste from a cafeteria to 56.3% in food waste from a canteen in Beijing with an average value of 45.6%  9.8%. In the case of TKN, the values ranged between 1.3% and 3.25% with an average value of 2.3%  0.57%. The SSFW and OFMSW were often reported to have comparatively lower TKN contents [20,28] than the food waste from canteens and other sources. A high TKN content is indicative of the high-protein nature of the substrate that could result in N loss from the substrate during composting, thus requiring adequate measures to control the ammonia emission. The average TP and TK values of food waste reported in the literature were 0.38  0.26 and 0.93  0.32. Mixed dishes, root/ tuber vegetables, and dairy products were reported to contain high potassium, while dairy products, mixed dishes, and animal flesh were higher in phosphorus [52]. Thus variations in the composition of food waste could be the reason for a wide range of values for both TP (0.05%–0.98%) and TK (0.29%–1.43%) contents of food waste. Considering the nutrition of microbes, the ratio between C and N is considered important. Carbon is the energy source, while protein is important for cell differentiation. The C/N ratio of food waste ranges from 9.3 to 24.5 with an average value of 17.3  3.7. For composting, the optimal initial C/N ratio of the composting mass should range from 25 to 35. During composting generally, the C/N ratio declines to a lower level due to the use of carbon for energy and nitrogen assimilation. The C/N ratio of food waste is generally much lower than the optimum values recommended for the composting process resulting in

TABLE 5 Total Organic Carbon (TOC), Total Kjeldahl Nitrogen (TKN), Ammonium Nitrogen (NH4+-N), C/N Ratio, Total Phosphorus (TP), and Total Potassium (TK) of Food Waste Reported in the Literature. Values are Presented in Dry Weight Basis. Food Waste Sourced Froma

Country

Household

Brazil, Salvador

c

Canteen

China

Kitchen

China, Beijing

TOC (%)a

TKN (%)a

NH4+-N (g/kg)a

1.5

C/N Ratiob

TP (%)a

TK (%)a

19.2

[76] c

9.7–18.1 37.3

References

[78]

0.58

[24]

Cafeteria

China, Beijing

30.3

2.63

11.5

[18]

FVW—cafeteria

China, Beijing

29.7

1.57

18.9

[18]

University restaurant

China, Beijing

19.3

[79]

Cafeteria

China, Beijing

21.3

Dining hall

China, Beijing

Canteen

China, Beijing

Dining hall

0.98

0.66

0.81 56.3

2.30

[43] [80]

24.5

[82]

China, Beijing

23.3

[83]

University restaurant

China, Dalian

18.6

[84]

University restaurant

China, Dalian

2.11

0.99

20.6

0.29

[85]

University restaurant

China, Dalian

2.59

0.52

14.5

0.93

[86]

Canteen

China, Jiangnan

2.98

19.0

[88]

Canteen

China, Nanning

2.58

21.0

[89]

Canteen

China, Shenzhen

16.7

[90]

Canteen

Denmark, Lyngby

3.25

SSFW

Finland, Forssa

2.39

[93] 0.27

1.00

[28]

SFW

Hong Kong

45.9

2.88

[46]

Household

Hong Kong

0.05

[94]

SFW

Hong Kong

0.08

[94]

Canteen

India, Assam

Household

India, Mumbai

21.2

0.10

0.63

[96]

Household

India, Mumbai

23.4

0.12

0.91

[96]

Canteen

Ireland

14.2

Household

Ireland

SFW

Italy

Cafeteriac

Roma, Italy

20.0

[98]

Cafeteriac

Roma, Italy

24.0

[98]

Cooked KW

Italy, Rome

2.90

[20]

FVW

Italy, Rome

2.40

[20]

OFMSW

Italy, Rome

1.30

[20]

SSFW

Italy, Treviso

2.55

Cafeteria

Japan, Tsukuba

2.51

Restaurant

Japan, Yamanashi

Cafeteria

Korea, Daejeon

Korean restaurant

Korea, Yongin

Canteen

KSA, Jeddah

Restaurant

Malaysia, Cameron Highlands

Cafeteria

Pakistan

1.71

[95]

[97]

0.74

[29]

2.48

[61]

0.35 17.2 14.8

0.88

0.27

0.64

[111] [100]

13.2

0.083

51.1

[28] [99]

1.46 2.98

1.00

0.82

[102] [103]

9.3

[104]

16.8

[106] (Continued )

TABLE 5 Total Organic Carbon (TOC), Total Kjeldahl Nitrogen (TKN), Ammonium Nitrogen (NH4+-N), C/N Ratio, Total Phosphorus (TP), and Total Potassium (TK) of Food Waste Reported in the Literature. Values are Presented in Dry Weight Basis—cont’d Food Waste Sourced Froma

Country

SSFW

Portugal, Lisbon

SFW

Scotland

OFMSW from mechanical biological treatment plant

Spain, Barcelona

SSFW

UK, Eastleigh

0.28

0.86

[28]

SSFW

UK, Hackney

0.64

1.29

[28]

SSFW

UK, Ludlow

0.54

1.43

[28]

UK, Luton

0.49

1.23

[28]

SFW (military rations)

USA

0.20

Grocery store

USA, Raleigh

48.2

[110]

Dining hall

USA, Raleigh

50.5

[110]

Hotel and conference center

USA, Raleigh

56.2

[110]

Restaurant

USA, Raleigh

50.1

FWe

Global

SSFW d

Average (SD) values a

TOC (%)a

TKN (%)a

NH4+-N (g/kg)a

C/N Ratiob

1.50 18.0 1.83

TK (%)a

References

0.50

[28]

0.28

[112]

14.1

[107]

[108]

[110] 1.60 (1.2)

45.6 (9.8)

TP (%)a

2.3 (0.57)

0.76 (0.4)

18.5 (5.9)

0.5 (0.3)

1.2 (0.7)

17.3 (3.7)

0.38 (0.26)

0.93 (0.32)

[25]

DM, Dry matter; FVW, fruit and vegetable waste; FW, food waste; KW, kitchen waste; OFMSW, organic fraction of municipal solid waste; OM, organic matter, SFW, simulated food waste; SSFW, source segregated food waste; TOC, total organic carbon; TKN, total Kjeldahl nitrogen. If TOC and TKN values are not reported, the C/N value was reported/calculated from the C and N of elemental analysis presented in this table. c Range of values of 12 samples. d FW mimics transportable, calorie-dense military rations. e Average (SD) of 102 samples from 70 studies. b

7 Elemental Composition and Light Metal Ions

29

N loss through ammonia (NH3) volatilization. Therefore it is necessary to mix food waste with bulking agents having high C such as sawdust, straw, etc., to adjust the C/N ratio [22]. However, when large pieces of wood or wood chips are used as bulking material, a high initial C/N ratio should be favorable as the woody materials do not degrade much during the active period of composting. In the case of anaerobic digestion, a C/N ratio of 10–30 appeared ideal to support microbial growth in anaerobic digesters [53, 54].

7 ELEMENTAL COMPOSITION AND LIGHT METAL IONS Elemental compositions (carbon, hydrogen, nitrogen, sulfur, and oxygen) of food waste were often reported in studies related to anaerobic digestion as these values can be used to calculate the theoretical biogas yields, while the C/N ratio is often used as a measure to evaluate the ammonium/ammonia toxicity during the anaerobic digestion process. The influence of C/N ratio on the composting process was discussed in Section 6. Sulfur content could be used to determine the level of desulfurization of the biogas and also to evaluate the competition between sulfate reducers and methanogens. Similar to the N, P, and K contents, many micronutrients such as Ca, Mg, Na, and Fe are essential for the growth and functioning of microbes [55]. The average C, H, O, N, and S contents of food waste reported were 47.7%  3.1%, 6.8%  0.5%, 35.2%  6.1%, 3.0%  0.8%, and 0.3%  0.4%, respectively (Table 6). A high carbon content makes food wastes useful substrates for both biological and thermal treatments; however, considering the high moisture content, often food wastes are the least preferred substrates for thermal treatments. Nonetheless, incineration of MSW instead of SSFW appears to be emerging as it offers multiple advantages. A nitrogen content of about 3% is ideal for the application of anaerobic digestion technology because the ammonium released from the organic matter could contribute to buffering of the reactor, especially in singe-phase anaerobic digestion reactors. As pointed out by Esteves and Devlin [30], the S content of food waste could result in H2S levels of up to 2000 ppm in the biogas causing issues regarding its removal from the biogas. Micronutrients such as Na, Mg, and Ca are also essential elements for microbial growth. Sodium concentrations of food waste range from 7.8 to 23.0 g/kg with an average of 13.5 g/kg, magnesium concentrations range from 0.5 to 2.0 g/kg with an average value of 1.1 g/kg, and calcium concentrations range from 1.3 to 30.0 g/kg with an average value of 11.3 g/kg (Table 6). Foods representing mixed dishes and soups were higher in sodium; nuts, mixed dishes, and legumes were higher in magnesium; and dairy products were higher in calcium [30]. Thus the composition of the food waste could affect Na, Mg, and Ca concentrations. The impact of these inorganic cations on the composting process appears negligible because the concentrations of these ions as listed in Table 6 are more or less in the range found in plants. However, during the anaerobic digestion process, the effectiveness of these ions has already been recognized. Na+,

TABLE 6 Results of Elemental Analysis of Food Waste Reported in the Literature. Na (g/kg)

Mg (g/kg)

Ca (g/kg)

Food Waste Sourced Froma

Country

C (%)

H (%)

O (%)

N (%)

S (%)

Shopping mall and food market

Australia, Sydney

46.1

5.7

41.0

1.7

0.2

Canteen

China

43.0–51.5

6.5–7.7

University restaurant

China, Beijing

48.2

6.9

Cafeteria

China, Beijing

53.3

Canteen

China, Beijing

University restaurant

China, Dalian

50.3

7.1

29.1

2.7

University restaurant

China, Dalian

49.5

7.0

34.6

2.4

8.1

0.8

University restaurant

China, Dalian

46.5

6.5

26.5

3.2

15.7

1.3

SSFW

Finland, Forssa

49.4

Household

India, Mumbai

0.1

7.8

0.5

7.1

[96]

Household

India, Mumbai

0.1

9.8

0.9

9.2

[96]

Canteen

Ireland

49.6

SSFW

Italy, Treviso

47.2

2.6

47.2

Restaurant

Japan, Yamanashi

48.3

3.3

0.2

Korean restaurant

Korea, Yongin

46.7

6.4

36.4

3.5

0.3

[102]

SFW

New Zealand

39.5

7.3

47.7

5.7

30 g/L and thus can be considered within the limit, although individual species may respond differently to these ions as influenced by the operating conditions.

8 CARBOHYDRATE, PROTEIN, AND LIPID CONTENTS The carbohydrate, protein, and lipid contents of food wastes reported in the literature are presented in Table 7. In a few publications, crude carbohydrate and crude protein contents were reported, while lack of sufficient methodological details did not allow the discrimination of these values against carbohydrate and protein contents. Similarly, many studies calculated the protein content based on the nitrogen content instead of direct analysis. On average, the carbohydrate content of food waste is about 50% and ranges between 16.6% and 74.6%. Cooked foods and some simulated food wastes [46,61] showed a high level of carbohydrates. If the carbohydrate contents of the simulated food wastes are not included, then the average is about 48.4%. The protein content in food waste ranged from 5.5% to 42.2% with an average value of 20.5%, while the average lipid content was 21.5%, close to the protein content. Carbohydrate, protein, and lipid are the three major macromolecules of organic matter. Of these, carbohydrate is generally higher than the other two fractions. A study conducted by WRAP [30] showed that the carbohydrate contents were increased by 50% in the winter compared with the summer season due to changes in diet as well as reduction in home composting. In contrast, protein contents were reported to be higher during the summer and a 40% reduction was observed in the winter season. Degradation of protein releases ammonium in anaerobic digestion reactors; therefore a high concentration could result in ammonia toxicity, while a low protein content could cause inadequate buffering. Thus the changes in protein content must be considered carefully during operation of anaerobic digestion reactors. Lipid contents were slightly higher

8 Carbohydrate, Protein, and Lipid Contents

33

TABLE 7 Carbohydrate, Protein, and Lipid Contents of Food Waste Reported in the Literature. Food Waste Sourced Froma

Country

Carbohydrate (% dry basis)

Protein (% dry basis)

Lipid (% dry basis)

References

6.7

[77]

6.0–41.3

[78]

28.9

[18]

5.2

[18]

Canteen

China, Hangzhou

42.7

11.2

Canteenb

China

16.6–71.9

17.6–42.2

d

e

Cafeteria

China, Beijing

8.6

14.7

FVW— cafeteria

China, Beijing

24.9d

13.6e

Canteen

China, Beijing

33.22

14.03

University restaurant

China, Dalian

60.5

14.4

32.0

[85]

University restaurant

China, Dalian

45.3

15.9

21.6

[86]

SFW

China, Hangzhou

Canteen

China, Jiangnan

Canteen

China, Shenzhen

Canteen

[81]

15.1

[87]

45.3

23.2

[88]

44.7

35.5

7.0

[90]

Denmark, Lyngby

28.0

19.1

[93]

SSFW

Finland, Forssa

17.6e

16.9

[28]

SFW

Hong Kong

74.0

18.0

10.0

[46]

Canteen

Ireland

59.0

18.1

17.4

[97]

SFW

Italy

72.2

17.5

5.6

[61]

Cooked KW

Italy, Rome

74.6

12.4

5.6

[20]

FVW

Italy, Rome

41.4

10.4

8.3

[20]

OFMSW

Italy, Rome

36.8

5.5

7.8

[20]

SS-FW

Italy, Treviso

21.5e

23.3

[28]

Cafeteria

Japan, Tsukuba

42.3

[99] (Continued )

34

Food Waste Properties

TABLE 7 Carbohydrate, Protein, and Lipid Contents of Food Waste Reported in the Literature—cont’d Food Waste Sourced Froma

Country

Carbohydrate (% dry basis)

Protein (% dry basis)

Lipid (% dry basis)

References

Cafeteria

Korea, Daejeon

73.8

[100]

Cafeteria

Korea, Daejeon

58.5

[101]

Korean restaurant

Korea, Yongin

61.7

SSFW

18.8

12.9

[102]

UK, Eastleigh

21.3e

16.1

[28]

SSFW

UK, Hackney

23.4e

17.2

[28]

SSFW

UK, Ludlow

25.7e

16.5

[28]

SSFW

UK, Luton

23.3e

16.2

[28]

e

[109]

Buffet leftovers at a casino

USA, Central NY

27.8

Grocery store

USA, Raleigh

18.6

27.0

[110]

Dining hall

USA, Raleigh

13.9

41.7

[110]

Hotel and conference center

USA, Raleigh

26.5

44.2

[110]

Restaurant

USA, Raleigh

22.3

38.3

[110]

FWc

Global

40.8 (23.8)

23.8 (14.7)

17.0 (9.1)

[25]

50.1 (14.4)

20.5 (7.2)

21.5 (11.0)

Average (SD) values a

DM, Dry matter; FVW, fruit and vegetable waste; FW, food waste; KW, kitchen waste; OFMSW, organic fraction of municipal solid waste; OM, organic matter, SFW, simulated food waste; SSFW, source-segregated food waste. Range of values of 12 samples. c Average (SD) of 102 samples from 70 studies. d Reported as crude fiber. e Reported as crude protein. b

in winter than the summer season because of the energy-rich diet during winter [30]. Carbohydrates are easily and rapidly hydrolyzed by enzymes to sugars, which are then degraded by acidogens to volatile fatty acids (VFAs), which are eventually converted into acetate, CO2, and H2 by acetogens. The rapid

9 Conclusions and Perspectives

35

acidification of carbohydrates results in a pH value as low as 4.0. This could be avoided by adding buffering substances to the reactor or adjusting the feed substrates [44,62,63]. Interestingly, the hydrolysis of the protein releases ammonium, which adds the benefit of buffering the acids generated in the reactor. However, a high ammonium concentration poses toxicity to the methanogens. Carbohydrate-rich substances are potential substrates for the production of H2 compared with proteins and lipids. Proteins are enzymatically hydrolyzed to peptides and amino acids, which are eventually fermented into VFA, CO2, NH4+, and S2–, as well as a little H. The NH4+ released during the degradation of proteins offers buffering of the anaerobic digestion reactors. Lipids are hydrolyzed into glycerol and fatty acids; the latter are eventually degraded into acetate and H2 through acetogens, which require a very low partial pressure of hydrogen. In the case of methane production, lipids have more potential than carbohydrates and proteins; however, a high lipid content causes imbalance among the microbes and reduces efficiency. Anaerobic digestion involves a delicate balance among different groups of bacteria and archaea carrying out different functions. Especially, the syntrophic relationship between methanogens and acetogens is crucial in sustaining the operation of the digester, which requires the environmental variables to be controlled with reference to the properties of the food waste. Therefore analysis of food waste can reveal its suitability to different treatment technologies.

9 CONCLUSIONS AND PERSPECTIVES Food waste generated at the retail and consumer levels of the food supply chain, and generated at the industrial level during processing, have been the focus of alternate energy substrates in the last few decades. Thermochemical and biological treatment options are available to unlock the energy potential of food waste, while the properties of food waste often determine the selection of technology. Generally, food waste has high moisture (48%95%) and VS (73%–98%) contents making it suitable for biological treatments. The average C, H, O, N, and S contents of the food waste reported were 47.7%, 6.8%, 35.2%, 3.0%, and 0.3%, respectively. Micronutrients such as Na, Mg, and Ca, which are essential for microbes, average at 13.5, 1.1, and 11.3 g/kg. Carbohydrate, protein, and lipid contents of food waste range from 16.6% to 74.6%, 5.5% to 42.2%, and 5.2% to 44.2%, respectively. Each of these components has advantages and disadvantages such as rapid degradation but acidification leading to low pH, ability to buffer but causes ammonia toxicity, and high energy content but impairs the syntrophic relationship in the anaerobic digestion reactor, respectively. A delicate balance between the nutrients is key to achieving high efficiency. Alternatively, different treatment strategies would enable the utilization of different types of food wastes efficiently, which requires critical knowledge of the properties of the waste to be treated.

36

Food Waste Properties

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[78] Y. Li, Y. Jin, A. Borrion, H. Li, J. Li, Effects of organic composition on the anaerobic biodegradability of food waste, Bioresour. Technol. 243 (2017) 836–845. [79] W. Zhang, S. Wu, J. Guo, J. Zhou, R. Dong, Performance and kinetic evaluation of semi-continuously fed anaerobic digesters treating food waste: role of trace elements, Bioresour. Technol. 178 (2015) 297–305. [80] J. Zhang, C. Lv, J. Tong, J. Liu, J. Liu, D. Yu, Y. Wang, M. Chen, Y. Wei, Optimization and microbial community analysis of anaerobic co-digestion of food waste and sewage sludge based on microwave pretreatment, Bioresour. Technol. 200 (2016) 253–261. [81] Z. Yong, Y. Dong, X. Zhang, T. Tan, Anaerobic co-digestion of food waste and straw for biogas production, Renew. Energy 78 (2015) 527–530. [82] C. Zhang, H. Su, T. Tan, Batch and semi-continuous anaerobic digestion of food waste in a dual solid-liquid system, Bioresour. Technol. 145 (2013) 10–16. [83] C. Song, Y. Zhang, X. Xia, H. Qi, M. Li, H. Pan, B. Xi, Effect of inoculation with a microbial consortium that degrades organic acids on the composting efficiency of food waste, Microb. Biotechnol. 11 (6) (2018) 1124–1136. [84] W. Zhang, L. Zhang, A. Li, Enhanced anaerobic digestion of food waste by trace metal elements supplementation and reduced metals dosage by green chelating agent [S, S]-EDDS via improving metals bioavailability, Water Res. 84 (2015) 266–277. [85] W. Zhang, W. Xing, R. Li, Real-time recovery strategies for volatile fatty acid-inhibited anaerobic digestion of food waste for methane production, Bioresour. Technol. 265 (2018) 82–92. [86] W. Zhang, B. Chen, A. Li, L. Zhang, R. Li, T. Yang, W. Xing, Mechanism of process imbalance of long-term anaerobic digestion of food waste and role of trace elements in maintaining anaerobic process stability, Bioresour. Technol. 275 (2019) 172–182. [87] J. Yin, X. Yu, Y. Zhang, D. Shen, M. Wang, Y. Long, T. Chen, Enhancement of acidogenic fermentation for volatile fatty acid production from food waste: effect of redox potential and inoculum, Bioresour. Technol. 216 (2016) 996–1003. [88] L. Yang, Y. Huang, M. Zhao, Z. Huang, H. Miao, Z. Xu, W. Ruan, Enhancing biogas generation performance from food wastes by high-solids thermophilic anaerobic digestion: effect of pH adjustment, Int. Biodeter. Biodegrad. 105 (2015) 153–159. [89] G. Shan, J. Xu, Z. Jiang, M. Li, Q. Li, The transformation of different dissolved organic matter subfractions and distribution of heavy metals during food waste and sugarcane leaves co-composting, Waste Manage. 87 (2019) 636–644. [90] C. Liu, H. Li, Y. Zhang, C. Liu, Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste, Bioresour. Technol. 219 (2016) 252–260. [91] J. Tang, X. Wang, Y. Hu, Y. Zhang, Y. Li, Lactic acid fermentation from food waste with indigenous microbiota: effects of pH, temperature and high OLR, Waste Manage. 52 (2016) 278–285. [92] N. Zhai, T. Zhang, D. Yin, G. Yang, X. Wang, G. Ren, Y. Feng, Effect of initial pH on anaerobic co-digestion of kitchen waste and cow manure, Waste Manage. 38 (2015) 126–131. [93] T. Fitamo, A. Boldrin, K. Boe, I. Angelidaki, C. Scheutz, Co-digestion of food and garden waste with mixed sludge from wastewater treatment in continuously stirred tank reactors, Bioresour. Technol. 206 (2016) 245–254. [94] F. Zan, J. Dai, Y. Hong, M. Wong, F. Jiang, G. Chen, The characteristics of household food waste in Hong Kong and their implications for sewage quality and energy recovery, Waste Manage. 74 (2018) 63–73. [95] K. Dhamodharan, V. Kumar, A.S. Kalamdhad, Effect of different livestock dungs as inoculum on food waste anaerobic digestion and its kinetics, Bioresour. Technol. 180 (2015) 237–241. [96] M.K. Manu, R. Kumar, A. Garg, Decentralized composting of household wet biodegradable waste in plastic drums: effect of waste turning, microbial inoculum and bulking agent on product quality, J. Clean. Prod. 226 (2019) 233–241. [97] J.D. Browne, J.D. Murphy, Assessment of the resource associated with biomethane from food waste, Appl. Energy 104 (2013) 170–177.

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[98] P. Pagliaccia, A. Gallipoli, A. Gianico, D. Montecchio, C.M. Braguglia, Single stage anaerobic bioconversion of food waste in mono and co-digestion with olive husks: impact of thermal pretreatment on hydrogen and methane production, Int. J. Hydrogen Energy 41 (2) (2016) 905–915. [99] Y. Ohkouchi, Y. Inoue, Direct production of L+-lactic acid from starch and food wastes using Lactobacillus manihotivorans LMG18011, Bioresour. Technol. 97 (13) (2006) 1554–1562. [100] S. Jang, D.-H. Kim, Y.-M. Yun, M.-K. Lee, C. Moon, W.-S. Kang, S.-S. Kwak, M.S. Kim, Hydrogen fermentation of food waste by alkali-shock pretreatment: microbial community analysis and limitation of continuous operation, Bioresour. Technol. 186 (2015) 215–222. [101] M.-S. Kim, J.-G. Na, M.-K. Lee, H. Ryu, Y.-K. Chang, J.M. Triolo, Y.-M. Yun, D.-H. Kim, More value from food waste: lactic acid and biogas recovery, Water Res. 96 (2016) 208–216. [102] L. Zhang, Y.-W. Lee, D. Jahng, Anaerobic co-digestion of food waste and piggery wastewater: focusing on the role of trace elements, Bioresour. Technol. 102 (8) (2011) 5048–5059. [103] M. Waqas, A.S. Nizami, A.S. Aburiazaiza, M.A. Barakat, Z.Z. Asam, B. Khattak, M. I. Rashid, Untapped potential of zeolites in optimization of food waste composting, J. Environ. Manage. 241 (2019) 99–112. [104] A. Malakahmad, N.B. Idrus, M.S. Abualqumboz, S. Yavari, S.R.M. Kutty, In-vessel co-composting of yard waste and food waste: an approach for sustainable waste management in Cameron Highlands, Malaysia, Int. J. Recycl. Org. Waste Agric. 6 (2) (2017) 149–157. [105] M. Zamanzadeh, L.H. Hagen, K. Svensson, R. Linjordet, S.J. Horn, Anaerobic digestion of food waste—effect of recirculation and temperature on performance and microbiology, Water Res. 96 (2016) 246–254. [106] M. Jabeen, Zeshan, S. Yousaf, M.R. Haider, R.N. Malik, High-solids anaerobic co-digestion of food waste and rice husk at different organic loading rates, Int. Biodeter. Biodegr. 102 (2015) 149–153. [107] S. Ponsa´, T. Gea, A. Sa´nchez, Anaerobic co-digestion of the organic fraction of municipal solid waste with several pure organic co-substrates, Biosyst. Eng. 108 (4) (2011) 352–360. [108] C.M. Asato, J. Gonzalez-Estrella, A.C. Jerke, S.S. Bang, J.J. Stone, P. C. Gilcrease, Batch anaerobic digestion of synthetic military base food waste and cardboard mixtures, Bioresour. Technol. 216 (2016) 894–903. [109] J. Masih-Das, W. Tao, Anaerobic co-digestion of foodwaste with liquid dairy manure or manure digestate: co-substrate limitation and inhibition, J. Environ. Manage. 223 (2018) 917–924. [110] V.M. Lopez, F.B. De la Cruz, M.A. Barlaz, Chemical composition and methane potential of commercial food wastes, Waste Manage. 56 (2016) 477–490. [111] A. Mahmood, R. Iguchi, R. Kataoka, Multifunctional food waste fertilizer having the capability of Fusarium-growth inhibition and phosphate solubility: a new horizon of food waste recycle using microorganisms, Waste Manage. 94 (2019) 77–84. [112] M. Cogan, B. Antizar-Ladislao, The ability of macroalgae to stabilise and optimise the anaerobic digestion of household food waste, Biomass Bioenergy 86 (2016) 146–155. [113] N. Ul Saqib, A.K. Sarmah, S. Baroutian, Effect of temperature on the fuel properties of food waste and coal blend treated under co-hydrothermal carbonization, Waste Manage. 89 (2019) 236–246.

Chapter | Three

Food Waste Generation and Collection V. Panaretou, Ch. Tsouti, K. Moustakas, D. Malamis, S. Mai, E.M. Barampouti, and M. Loizidou Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens, Athens, Greece

1 INTRODUCTION During recent years, food waste is getting increased attention globally due to the environmental, economic, and social impacts it generates. At a worldwide level, it has been broadly recognized that we are going through a period of resource scarcity. In spite of the growing global stresses on food production, about onethird (1/3) of the food produced for human consumption (1.3 billion tons per year) never reaches its intended target (human stomach) and is wasted [1]. On a social level, it is progressively harder to reconcile food wastage with increasing food poverty. Rising food prices forces more and more of the global population into food poverty. It is estimated that 12% of the earth’s population (i.e., 868 million individuals) suffer from undernourishment [2]. The United Nations 2030 Agenda for Sustainable Development, Goal 2, targets to end all forms of hunger and malnutrition by 2030, ensuring that all people will have access to food. Regarding the environmental implications, food waste is considered an important pressure, related to the depletion of water and land resources, and increased greenhouse gas emissions, affecting negatively climate and natural habitats. All the resources used throughout the food supply chain are wasted as well. Food production and consumption contribute to an estimated 20%–30% of all EU environmental impacts. Food waste in landfills produces harmful methane with a global warming potential (GWP) 21 times greater than CO2. In total, 47 million tonnes of EU household food waste produce 89.3 million tonnes of CO2 equivalent (CO2-eq) considering 1.9 tonnes CO2-eq per tonne of food waste [3, 4]. At a global level, this burden is multiplied as GHG emissions due to food waste are much higher and equal to 3.49 Gt CO2-eq [5]. 43 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00003-8 Copyright © 2021 Elsevier Inc. All rights reserved.

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Regarding the economic implications the numbers hidden in this waste are considerable. For example, in the United States, the money lost due to food waste by distribution and retail businesses (37% contribution), along with restaurants, catering, and domestic consumers (63% contribution), reach up to USD 198 billion every year. For a four-membered household, this is translated into USD 1600 yearly expenses [6]. A similar study of the Department for Environment, Food and Rural Affairs (DEFRA) in the United Kingdom, showed that the average amount spent on avoidable food waste by each household is equal to £470 per year [7]. If someone wants to acquire the broader picture, then the numbers are devastating. As a gross summary of impacts, the societal costs of food wastage estimated here amounted to about USD 2.6 trillion, of which USD 700 billion are societal costs of environmental impacts, USD 1 trillion is costs from economic losses of wasted and lost production, and USD 900 billion are costs due to individual well-being losses [5]. The United Nations 2030 Agenda for Sustainable Development, Target 12.3, calls for the reduction of food waste along the supply chain, along with a 50% decrease in food waste per capita at the consumer and retail stages by 2030 [8]. Biowaste can amount to up to half of the total municipal solid waste produced, and food waste holds a significant share within this fraction [9]. It is worth noting that the knowledge of the percentage and composition of food waste within the total waste produced plays an important role and is considered a prerequisite for choosing the most appropriate method for managing this susceptible fraction efficiently [10]. In the context of recording the current situation regarding the generation and composition of food waste, it was found that the share of food waste across the food supply chain differs between developing and developed regions, even between regions and cities in the same country. Food waste accounting is the baseline for food waste policy design related to reduction and prevention targets, as well as valorization policies [11]. Developing an effective strategy against food waste requires knowing not only the reason leading to food waste generation but also the variation of contribution among the stages of the food supply chain to the total amount of food wasted and which types of food are wasted the most [12]. Food waste composition and quantity affect the selection of the most appropriate treatment technology; therefore these parameters need to be greatly considered. The way food waste is collected from producers is also a crucial step in the whole management chain to achieve sustainability. This chapter is organized as follows: Section 1 is the introduction. Section 2 describes basic information related to the food waste problem. In particular the following issues are described: various definitions attributed to food waste, the problem in numbers, food waste composition characteristics, and physicochemical properties. Following in Section 3 the aspect of food waste collection is introduced. A multifaceted analysis is carried out, starting with the influence factors of a food waste collection system and moving on to the available equipment for the setup of such systems. This section is

2 Food Waste Generation

45

completed with the issues of monitoring and evaluation, followed by the communication planning of food waste collection systems. Finally, conclusions are driven in Section 4.

2 FOOD WASTE GENERATION 2.1 Food Waste Definitions Up to now, there is not a uniform term used to define food waste. Different professional bodies, international institutions, and state governments use different definitions to describe what food waste is. Consequently the terminology used to define and explain food waste varies, among other things, in what food waste consists of, how it is produced, and where or what it is discarded from or produced by. According to UNEP-FAO, three (3) distinctive terms are defined. Food loss refers to “a decrease in mass (dry matter) or nutritional value (quality) of food that was originally intended for human consumption. These losses are mainly caused by inefficiencies in the food supply chains, such as poor infrastructure and logistics, lack of technology, insufficient skills, knowledge and management capacity of supply chain actors, and lack of access to markets. In addition, natural disasters play a role.” Food waste refers to “food appropriate for human consumption being discarded, whether or not after it is kept beyond its expiry date or left to spoil. Often this is because food has spoiled, but it can be for other reasons such as oversupply due to markets, or individual consumer shopping/eating habits.” Food wastage refers to “any food lost by deterioration or waste. Thus the term ‘wastage’ encompasses both food loss and food waste” [13]. Regarding the US Environmental Protection Agency (USEPA), food waste is defined as “uneaten food and food preparation wastes from residences and commercial establishments such as grocery stores, restaurants, and produce stands, institutional cafeterias and kitchens, and industrial sources like employee lunchrooms” [14]. On the basis of official legislation, within European Union, more specifically considering Directive 75/442/EEC, Council Directive 91/156/EEC, Directive 2006/12/EC, and Directive 2008/98/EC, there was no specific definition for food waste in these previous documents. Only the recently published EU Directive 2018/851 actually refers to the term “food waste.” In particular, in point 4a, “food waste” means “all food ….that has become waste” and the related “article 2” that refers to the definition of “food”: “... food (or “foodstuff”) means any substance or product, whether processed, partially processed or unprocessed, intended to be, or reasonably expected to be ingested by humans.” Furthermore the study produced by Bio Intelligence Service [4] defined the term as follows: “food waste is composed of raw or cooked food materials and includes food loss before, during or after meal preparation in the household, as well as food discarded in the process of manufacturing, distribution, retail and food service activities. It comprises materials such as vegetable peelings, meat trimmings, and spoiled or excess ingredients or prepared food as well as bones, carcasses and organs. Food waste can be both edible and inedible.” Moreover the European FP7 project, EU

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Food Waste Generation and Collection

FUSIONS (2012–2016), focused on food waste across Europe, had the objectives to collect data from EU-28 member states, and develop (1) a uniform definition for “food waste” and (2) a methodology for measuring food waste across the different stages of the value chain. The definition proposed is “Food waste is any food, and inedible parts of food, removed from the food supply chain to be recovered or disposed (including composted, crops plowed in/not harvested, anaerobic digestion, bioenergy production, cogeneration, incineration, disposal to sewer, landfill or discarded to sea)” [15]. In addition the Waste & Resources Action Programme (WRAP) of the United Kingdom has been working as a world pioneer on the estimation and handling of food and drink waste since 2007. WRAP’s approach distinguished food waste into three different types: “avoidable,” “possibly avoidable,” and “unavoidable” [16]. In 2015 WRAP updated the food waste definition, in line with FUSIONS approach, by the following: “Food and the inedible parts of food removed from the food supply chain (or household) to be recovered or disposed of (including - composted, anaerobic digestion, incineration, disposal to sewer or landfill). This definition excludes waste prevention activities, namely redistribution for human consumption, or diverted to feed animals.” In recent WRAP studies, food waste is distinguished into two groups: “wasted food (edible parts)” and “inedible parts” [17]. Numerous other studies exist in literature, approaching the food waste definition and measurement in different ways, depending on the focused stage of the supply chain or geographical boundaries, that is, local, regional, national, and global [15, 18]. Therefore careful considerations should be made when comparing data from different sources to understand how food waste is defined and how it is quantified. In the following paragraphs the term food waste used does not consider a differentiation between avoidable and unavoidable food waste categories, but the whole fraction. The review across the globe that follows aimed at acquiring a quantified picture of the food waste problem in low-medium/high-income countries, providing comparative information for the different supply stages (i.e., agricultural production, postharvest, processing, distribution, and consumption). In addition, main categories found in food waste composition analysis (e.g., cereals, fruits and vegetables, meat, dairy products, and fish and seafood), and typical properties are presented. The quantity, the type of producer (industrial, domestic, etc.), and the characteristics of this fraction are critical aspects for the organization of the collection method, which subsequently can have a determining effect on the treatment and disposal stages.

2.2 Quantification—The Problem of Food Waste in Figures At global level, it is estimated that food loss and waste are approximately 1.3 billion tonnes every year, which is almost one-third of the food produced for human consumption [19]. For every amount of food wasted, natural resources are also wasted, with 20% of the fresh water consumption to be spoiled for the aforementioned food loss globally [13]. The estimated food wasted is

47

2 Food Waste Generation

responsible for about 8% of the anthropogenic greenhouse gas emissions globally [20] and 38% of the energy consumed in the food supply chain [21]. Although food loss and waste levels in industrialized countries are as high as in developing countries, their distribution occurs at different levels of the food supply chain [1]. A study published in 2018 by the Swedish Institute for Food and Biotechnology presented data by grouping countries and categorizing regions as low and medium/high income. The comparison of data showed that food loss and waste occur across different stages of the food supply chain. Countries of Europe, Industrialized Asia, Canada, the United States, and Oceania are considered as medium/high income, while countries of South/Southeast Asia, North Africa, West and Central Asia, sub-Saharan Africa, and Latin America are considered as low income [21]. As shown in Fig. 1, in medium/high-income countries, food loss and waste at the stage of consumption rises up to 33%, while at the same stage of the food supply chain in low-income countries, loss accounts for only 9%. On the other hand, it is estimated that in low-income countries, food loss and waste in the stage of postharvest is up to 30% with medium/high-income countries reaching the 16% of food loss and waste at this stage [22]. According to literature [1, 13, 23, 24], the causes of food losses and waste are various and differ along the supply chain in developed and developing countries, as shown in Table 1 later. Based on a study of the World Resources Institute in 2013, Fig. 2 depicts that “fruits and vegetables” lost or wasted account for the 44% of total global food loss and waste produced, with “roots, tubers,” and “cereals” following with 20% and 19%, respectively. “Milk products,” “meat,” “oilseeds and pulses,” and “fish and seafood” categories have smaller shares, while it needs to be

Food loss and waste in different stages of the food supply chain for low and medium/high income countries

Low income

Medium/high income

0%

208 mil ton

188 mil ton

205 mil ton

10%

Agricultural production

105 mil ton

20%

30%

Post-harvest

40%

78 mil ton

70 mil ton 69 mil ton

50%

Processing

60%

92 mil ton

59 mil ton

221 mil ton

70%

Distribution

80%

90%

100%

Consumption

FIG. 1 Comparative illustration of food loss and waste in different stages of the supply chain for low- and medium
/high-income countries in weight (million tonnes) and percentage. Data from J. Gustavsson, C. Cederberg, U. Sonesson, A. Emanuelsson, The methodology of the FAO study: Global Food Losses and Food Waste - extent, causes and prevention - FAO, 2011, SIK Institutet f€ or livsmedel och bioteknik, G€oteborg, Sverige, 2013.

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Food Waste Generation and Collection

TABLE 1 Overview of Causes for Food Losses and Waste per Different Stage of the Supply Chain. Stage of Food Supply Chain

Causes

Agricultural production

• • • • •

Premature harvests to cover market needs (nutritional value lost) Uncollected crops due to low, not profitable market prices Poor crop harvesting techniques Animal casualties Extreme weather conditions/pest attacks

Postharvest, handling, and storage

•

Poor transportation and/or packaging means or insufficient networks from farm to the industry/markets Inadequate storage conditions (e.g., increased humidity and temperature) and improper means “Injured” or with marks food products due to collection and threshing processes Rejection of edible food due to industry high esthetic criteria related to weight, size, shape, color, etc. Livestock casualties during transportation to meat-processing industries

• • • • Processing

• • •

Distribution

• • •

Consumption

• • • • • • •

Waste and spillage during washing, peeling, slicing, canning, and processing of food products Inefficient or damaged packaging of fresh produced food leading to spoilage Inadequate storage conditions of fresh production (e.g., increased humidity and temperature) and improper storage means Losses and waste due to market esthetic/quality criteria related to damaged packaging, weight, size, shape, color, etc. Overdisplay of products in supermarkets that are not purchased before reaching the sell-by date Inefficient projections for consumption demands leading to high ordering of products Large portion meals served in restaurants Limited reuse or redistribution due to hygienic risks and legislation obstacles Large packaging usually offered with discounts in the supermarkets, attractive for consumers’ purchase Poor food purchase planning leading to overpurchase of food and subsequent disposal at household level due to expired date or spoilage Improper storage conditions, not prioritizing consumption order according to expiry dates Overpreparation of meals at household level Perception that disposal is cheaper than reusing food leftovers

Source: From J. Gustavsson, C. Cederberg, U. Sonesson, R. van Otterdijk, A. Meybeck, Global Food Losses and Food Waste – Extent, Causes and Prevention, FAO, Rome, 2011, 9–21; FAO, Food Wastage Footprint; Impacts on Natural Resources, FAO, Rome, 2013; C.P. Porral, C. Medı´n, A. Faina, C. Losada-Lo´pez, Can marketing help in tackling food waste? Proposals in developed countries. J. Food Prod. Market. 23 (1) (2016) 42–60, https://doi.org/10.1080/10454446.2017. 1244792N. Raak, C. Symmank, S. Zahn, J. Aschemann-Witzel, H. Rohm, Processing- and product-related causes for food waste and implications for the food supply chain. Waste Manag. 61 (2017) 461–472https://doi.org/10.1016/j.wasman. 2016.12.027.

2 Food Waste Generation

49

Global food loss and waste by commodity 2% 4% 3%

8%

Cereals

19%

Roots and tubers Fruits and vegetables Oilseedsa nd pulses 20%

Meat Milk

44%

Fish and seafood

FIG. 2 Food loss and waste by commodity by weight generated in 2009. Data from B. Lipinski, C. Hanson, J. Lomax, L. Kitinoja, R. Waite, T. Searchinger, Reducing Food Loss and Waste. Working Paper, Installment 2 of Creating a Sustainable Food Future., World Resources Institute, Wasinghton, DC, 2013.

mentioned that food loss and waste of herbs, spices, coffee, tea, cocoa, sugar, honey, alcoholic beverages, and confectionery products have not been considered in the study [25]. In any case, not all waste should be perceived as simply equivalent to the quantity lost. For example, meat products involve high environmental impacts due to not only intensive water, land use, and GHG emissions per unit mass produced but also energy during the transport and processing, in combination with the high market price. Therefore prevention and reduction of such waste need equal consideration as other commodities, even though their share in wasted calories or weight is slighter.

2.2.1 EUROPE It is estimated that 88 million tonnes of food are annually wasted in the European Union (EU), which accounts for almost 20% of the total food produced. At the same time, 43 million people cannot bear the expense of proper nutrition every day. In the EU, more than half (i.e., 47 million tons 4 million tons) of the total food waste is produced in households, while about 70% of food waste comes from household, food service, and retail sectors [26]. According to the EU project FUSIONS, 173 kg of food waste was produced in the EU-28 per person in 2012 [3], while according to a recent report of the European Commission, it is estimated that 161 kg per person were produced in 2012 [27]. Based on different studies carried out, within 2010–17, for the quantification of food waste at a European level, food waste average generation values were found to vary from 173 to 290 kg cap
1 yr
1 [28]. The effect of different quantification methods and definitions on measuring food waste can be further imprinted by taking a closer look at the food waste supply chain. Based on the results of six different studies carried out to quantify the food waste produced presented in Fig. 3, it can be seen that the stage of

50

Food Waste Generation and Collection Food waste generation in the EU according to different studies

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Monier et al., 2010 Consumption

FAO,2011

Distribution

Bräutigam et al., 2014

FUSIONS,2016 Tisserant et al., 2017

Manufacturing

Van Holsteijn et al., 2017

Primary production and post‐harvest

FIG. 3 Comparative illustration of food waste generation in EU in different stages of the supply chain based on different studies. Data from C. Caldeira, S. Corrado, S. Sala, Food Waste Accounting - Methodologies, Challenges And Opportunities, European Union, Luxembourg, 2017.

consumption is on average responsible for 50% of the food waste produced at a European level, with values ranging from 34% to 65%, while the stage of distribution seems to contribute from 5% to 13% to the food waste produced. Rather interesting fluctuations are observed at the manufacturing stage and the stage of primary production and postharvest, with values ranging from 12% to 41% and from 0% to 47% of food waste produced, respectively [28].

2.2.2 ASIA According to FAO [1], food waste in Industrialized Asia, that is, Japan, China, and South Korea, is 240 kg cap
1 yr
1, while in South/Southeast Asia, it is 120 kg cap
1 yr
1. Focusing on industrialized Asia and the country of China, the annual amount of food loss and waste occurring before final consumption appears to be almost equal to the amount of food that is imported, reaching up to 6% [29]. It seems that most food waste occurs at the consumption stage for industrialized Asia, with postharvest stage being mainly responsible for the food waste occurring in South/Southeast Asia where waste at consumption stage rises up to only 11 kg cap
1 yr
1 [1]. General trends show that high-income regions contribute more to food waste generation at the consumption stage when lower-income regions seem to suffer greater loss at the postharvest stage [30], as presented in Fig. 4. 2.2.3 AMERICA According to the Commission for Environmental Cooperation [31], in North America, that is, Canada, the United States, and Mexico, 168 million tonnes of food loss and waste is estimated to be produced per year. The US food loss and waste are estimated to be around 75% of the total food wasted in North America, while Canada and Mexico contribute around 8% and 17%, respectively. It is

2 Food Waste Generation

51

Food waste generation in Asia for different stages in the food supply chain 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Industrialized Asia Agricultural production

South/Southeast Asia

Post-harvest

Processing

Distribution

Consumption

FIG. 4 Comparative illustration of food waste generation in Asia in different stages of the supply chain. Data from FAO, Food Loss and Waste and the Right to Adequate Food: Making the Connection, FAO, Rome, 2018.

of great interest that on a per capita basis, the food waste produced in the United States and Canada is similar with values of 415 and 396 kg cap
1 yr
1, respectively, with Mexico producing around 249 kg cap
1 yr
1 [31]. As depicted in Fig. 5, for both Canada and the United States, food loss and waste pattern along the food supply chain seems to be similar with the stage of

Food waste generation on North America for different stages in the food supply chain 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Mexico Pre-harvest

Canada Post-harvest

Processing

United States Distribution

Consumption

FIG. 5 Comparative illustration of food waste generation in North America in different stages of the supply chain studies. Data from CEC, Characterization and Management of Food Loss and Waste in North America, Commission for Environmental Cooperation, Montreal, 2017.

52

Food Waste Generation and Collection

consumption accounting for the largest share of food loss and waste produced in each country, almost 45%. In Mexico, food loss and waste seem to be more evenly distributed along the different stages of the supply chain, with the stage of preharvest showing the highest losses of around 32% and the stage of consumption contributing with the lowest losses of 14% [31]. Concerning Latin America and the Caribbean, it is estimated that they are responsible for around 6% of global food losses, while at the same time, at least 15% of the available food in the region is lost or wasted every year [32]. Each year, more than 127 million tonnes of food are wasted in Latin America that correspond to 223 kg cap
1 yr
1, food losses that could be sufficient to meet the nutritional requirements of 300 million people [33].

2.3 Food Waste Properties The vast majority of food waste is collected either by source separation systems that are considered a good practice or through mixed municipal solid waste collection that should be followed by mechanical separation and treatment to recover organics and recyclable materials. The quality characteristics of food waste recovered in the aforementioned cases is affected by the collection system. The determination of food waste properties is essential as it affects the performance of downstream management systems. According to literature, food waste properties can be classified into four main categories, namely, physical, chemical, elemental, and bromatological, representing characteristics that are more or less related to the efficiency of the subsequent treatment methods. Therefore, in this section, an effort was made to gather representative literature data related to food waste properties per se.

2.3.1 PHYSICAL PROPERTIES The physical classification of food waste is determined by the percentage of each individual fraction composing food waste. Since there are different categorization criteria for municipal solid waste, there is no standardized methodology that calculates the individual components of MSW, let alone food waste [34, 35]. Many different methods have been used throughout Europe and the rest of the world, and even within the same country, different ways of accounting can be used [36–38]. In Table 2 the classification of food waste is presented as sourced from literature [16, 39, 40]. The composition differentiates significantly from place to place, even between seasons of the same area as shown by Malamis et al. [40] and Alibardi and Cossu [41]. Nevertheless, the studies report that fruit and vegetable factions acquire the largest share of food waste composition (>45% wet weight). Due to the increased physical heterogeneity of food waste, its particle size varies significantly. This size differentiation is more evident among food waste individual fractions [42]. Therefore physical pretreatment processes are usually applied for size reduction and homogenization, aiming to increase and optimize the surface area–to–volume ratio prior to any downstream process [42, 43]. Food waste density is not reported consistently in literature, and it is dependent on the level

2 Food Waste Generation

53

TABLE 2 Categorization System Used for Compositional Analysis of Food Waste. Heaven et al. [39]

Quested et al. [16]

Malamis et al. [40]

1a Fruit and vegetable waste 1b Fruit and vegetables (whole) 1c Large stones, seeds, and fibrous materials

1a Fresh vegetables and salads 1b Fresh fruit 1c Processed vegetables and salad 1d Processed fruit

1 Vegetables and salads

2 Pasta/rice/flour/cereals

2 Staple foods

2 Fruits

3 Bread and bakery

3 Bakery

3 Bread and bakery

4a Meat and fish 4b Bones

4 Meat and fish

4 Meals (homemade and preprepared)

5a Dairy 5b Egg shells

5 Dairy and eggs

5 Pasta/rice/flour/cereals

6 Drinks

6a Confectionery and snacks 6b Cake and desserts

6 Meat and fish

7a Confectionery and snacks 7b Desserts

7a Condiments, sauces, herbs, and spices 7b Meals (homemade and preprepared)

7 Dairy and eggs

8a Condiments 8b Mixed meals

8 Other

8 Cake, desserts, confectionary and snacks

9 Other food

9 Drinks

10 Biodegradable bags

10 Paper

11 Garden waste

11 Garden waste

12 Paper and card

12 Other biowaste, organic materials of less than 15 mm that could not be classified into the earlier listed categories

13a Plastic containers 13b Plastic film (nonbiodegradable) 13c Metals 13d Glass 13e Miscellaneous

13 Impurities, that is, plastics, metals, glass, plastic bags

of compaction and degradation (freshness) of food waste that in turn are related to the sorting method and equipment used (e.g., bins and containers), the type of collection and transportation vehicle (e.g., compaction and no compaction), storage, etc. An indicative density range is between 290 and 750 kg/m3 [40, 44–47] for source-separated food waste constituting one of the heaviest MSW streams. Impurities in sorted food waste is a physical parameter that

54

Food Waste Generation and Collection

affects the subsequent treatment and thus end products’ quality. The level of physical impurities has been reported to be related to food waste collection method [40]. Door-to-door collection has been proven to achieve food waste recovery with less nonbiodegradable impurities (e.g., glass, metals, and plastics) compared with road container collection, where the bins are unprotected and anonymous [48]. In addition, end products resulting from the biological treatment of source-separated inputs (either door-to-door or road container collection) have been shown to meet the impurities level thresholds more easily compared with mechanically separated food waste from mixed MSW that output (compost/digestate) is characterized by visually noticeable level of unwanted materials [49].

2.3.2 CHEMICAL CHARACTERISTICS Literature provides numerous studies on the chemical characteristics of organic fraction of municipal solid waste, including food waste. The selection of chemical properties to be analyzed depends on the subsequent treatment step envisaged and on the impact they have on bioconversion performance. The most common chemical characteristics for food waste valorization are pH, humidity, total solids, volatile and fixed solids, total nitrogen, and phosphorous. These parameters are related to the biodegradability of food waste and its nutrients content to be used as feedstock in biological processes [42]. Table 3 presents food waste chemical characteristics among different countries and places, as extracted from literature [50]. A site-specific approach was applied considering the high fluctuation of food waste chemical properties due to the increase dependency on factors related to regionality, social and economic status, dietary habits, and waste management policies [42]. Information on sampling strategy is also given aiming to provide information about (1) the sampling frame in terms of the food waste producer types diversity (restaurants, households, catering, etc.), (2) the collection period and frequency, and (3) the origin food waste sampled. According to the data provided on sorted food waste, the average pH is 5.1  0.6 ranging from 4.1 to 6.2. pH in food and food products ranges from high-acid (pH, lower than 4.6) to high-alkaline (pH 8–10) products. Although the acidity of food and thus food waste may occur naturally, the acidic environment of food waste could also be related to the partial degradation of soluble readily degradable organic compounds (e.g., sugars) and the subsequent formation of volatile organic acids [51]. Food waste constitutes a fraction with increased humidity level that makes it difficult to handle throughout the management chain (i.e., separation, collection, transportation, and processing). Water content and TS levels range from 59.4% to 87.8% and from 12.8% to 40.6%, respectively, and with an average of 72.4  6.5% and 27.6  6.5%, respectively. Remarkably low moisture levels were reported in Padova (IT) and Leicester (UK) at 25% and 30% accordingly, much lower than the third lower value recorded in Uppsala (SE) at 59.4%. It is stated that for those two areas, the food waste sampling frame in terms of producers’ type inclusion is

TABLE 3 Food Waste Chemical Characteristics and Sampling Approach in Different Areas. Sampling

Continent

Country

City

pH

Water (% wb)

Africa

Tunisia

Sfax

5.6

84.5

15.5

14.2

–

–

America

Canada

Montreal

4.1

87.8

12.2

–

20.0

Greenland

Sisimiut

–

62.6

37.4

33.7

USA

California

–

69.1

30.9

India

Indore

85.0

Korea

Changwon

Lebanon

Asia

Europe

TS (% wb)

VS (% wb)

TKN (g/kg db)

TP (g/kg db)

Frame

a

Period/ Frequency

Food Waste Ooriginb

Reference

–

–

Mixed MSW

[60]

–

M

–

SS

[46]

37.2

34.8

M

2 Weeks/daily

Mixed MSW

[61]

26.4

9.8

1.6

H

8 Weeks/daily and weekly

Mixed MSW

[62]

15.0

13.3

11.3

–

–

–

[63]

83.7

16.3

14.0

37.7

3.5

L


/daily

SS + other organics

[64]

Beirut

81.4

18.6

17.2

–

3.8

L

Two batches

SS

[65]

Turkey

Ankara

64.4

35.6

33.8

20.2

–

L

–

SS

[66]

Czech Republic

Prague

6

67.5

32.5

23.1

42.6

2.2

M–H

1 Year/weekly

SS + other organics

[10]

Denmark

Copenhagen

–

72.0

28.0

22.9

25.9

6.3

H

1 Year/frequent

SS

[67, 68]

Denmark

Vejle

–

70.0

30.0

24.0

23.0

5.0

H

1 Year/frequent

SS + other organics

[67, 68]

Denmark

Kolding

–

67.0

33.0

27.1

23.9

5.2

H

1 Year/frequent

SS + other organics

[67, 68]

Denmark

Aalborg

–

70.0

30.0

25.7

–

5.1

H

1 Year/frequent

SS + other organics

[68, 69]

Denmark

Kolding

–

68.3

31.7

26.4

–

5.0

–

–

–

[70]

Denmark

Grindsted

–

64.4

35.6

30.7

17.7

–

H

1 Year/frequent

SS

[68]

Denmark

Gistrup

4.6

70.0

30.0

24.3

21.7

–

–

–

–

[71]

–

70.2

29.8

–

–

–

–

–

–

[72, 73]

Denmark

5.2

Continued

TABLE 3 Food Waste Chemical Characteristics and Sampling Approach in Different Areas—cont’d Sampling

Continent

Country

City

pH

Water (% wb)

Finland

Forssa

5.3

73.0

27.0

24.9

24.1

France

Rennes

5.3

78.7

21.3

17.5

21.1

Italy

Padova

–

69.5

30.5

28.1

25.2

Italy

Lacchiarella

4.3

77.7

22.3

19.7

17.9

Italy

Udine

–

70.0

30.0

27.6

24.0

Italy

Milan

4.4

75.8

24.2

22.2

Italy

Verona

–

71.2

28.8

Italy

Treviso

6.2

72.5

Italy

Padova

–

Portugal

Lisbon

Spain

Different cities

Spain

TS (% wb)

VS (% wb)

TKN (g/kg db)

TP (g/kg db)

Frame

2.6

a

Period/ Frequency

Food Waste Ooriginb

Reference

H

1 Sample

SS + other organics

[74]

L

–

SS

[75]

H

5 Samples

SS

[41]

H

1 Sample

SS

[76]

2.1

M

–

SS

[77]

20.7

2.1

H

1 Sample

SS + other organics

[78]

22.8

97.2

8.3

–

–

SS + other organics

[79]

27.5

23.8

25.5

3.6

H

1 Sample

SS + other organics

[74]

25.0

75.0

67.5

8.7

–

H

–

SS + other organics

[80]

–

66.2

33.8

27.6

15.1

5.0

M–H

2 Weeks/5 samples

SS

[74]

5.3

70.8

29.2

24.8

26.5

–

H

21 Samples

SS + other organics

[72]

4.6

76.6

23.4

0.0

–

–

–

10 Samples

SS

[81]

3.8

Spain

Catalonia

5.9

78.3

21.7

0.0

–

0.3

H

1 Sample/site

SS

[72, 81]

Spain

Madrid

–

66.9

33.1

27.1

–

–

H

1 Sample/site

SS

[72, 82]

Spain

Catalonia

–

74.0

26.0

0.0

–

–

–

–

SS + other organics

[72]

a

Sweden

Uppsala

–

59.4

40.6

0.0

–

–

–

–

SS + other organics

[72]

Sweden

Uppsala

–

65.8

34.2

0.0

–

–

–

–

SS + other organics

[72]

UK

Luton

5.1

76.3

23.7

21.6

31.2

5.1

M

1 Sample

SS

[74]

UK

Eastleigh

5.7

71.4

28.6

26.9

27.3

2.8

H

1 Sample

SS

[74]

UK

Southampton

–

72.3

27.7

24.4

32.1

6.9

H

14 Months/daily and fortnight

SS

[83]

UK

Leicester

30.0

70.0

36.1

–

–

H

–

Mixed MSW

[84]

UK

Newtown

4.7

76.3

23.7

21.7

34.2

5.4

–

–

–

[85, 86]

UK

Wales

–

72.3

27.7

25.7

7.3

0.9

M

Multiple sampling

SS

[87]

Diversity of FW producers H, high; M, moderate; L, low. SS: FW source separated; other organics: organic materials such as garden waste, paper, and cardboard other than food waste.

b

58

Food Waste Generation and Collection

considered high but no data are given on the sampling period and collection frequency. VS fluctuates significantly from site to site (range 13.3%–67.5% and average 25.7  9.2%) that is also depicted to the VS/TS ratio (range 51.6%–94.9% and average 85.8  8.1%). However, the elevated VS content in conjunction to the increased humidity content classifies food waste as a highly putrescible waste stream susceptible to biological transformations. High variation between reported areas is also presented for TKN and TP having a range of 7.3–97.2 and 0.3–34.8 g/kg, respectively.

2.3.3 ELEMENTAL PROPERTIES Elemental analysis is used to provide information about element composition of food waste. Table 4 shows the percentage composition of carbon (C), hydrogen (H), nitrogen (N), and sulfur (S) for the case studies reported in literature [50]. Carbon content of food waste ranges from 31.5% to 51.3% TS with an average of 44.56  5.5%. Hydrogen, nitrogen, and sulfur are reported at much lower levels in the range of 0.4%–6.6% TS. In regard to elemental composition, no significant differentiation is reported in comparison with the level of food waste sample representation and food waste sorting method. The stoichiometry of sorted food waste according to Barampouti et al. [50] is C20H36O16N, whereas LiwarskaBizukojc and Ledakowicz [52] reported a stoichiometry of C25H42.5O20N. Metals are naturally present in the environment and thus in food waste. Naturally occurring metal concentration is beneficial for the biological processing of food waste and for the subsequent use of organic end products, for example, compost and digestate. However due to industrialization and urbanization, the extensive use of metals in manufacturing processes has been reported to be connected to elevated concentrations of heavy metals in food waste. The long-term bioaccumulation and persistent nature of heavy metals can be toxic to plants and through the food chain that may impact the environment and human health [53]. The most commonly heavy metals that are present in biological processing outputs in higher concentrations than the background values in the receiving soil are Zn, Cu, Pb, Cr, Ni, Hg, and Cd [54]. According to Malamis et al. [40] and the JRC-IPTS report in 2014 [49], it is recorded that mixed food waste consistently lead to higher concentrations in certain metals compared with sorted food waste. This subsequently inhibits mixed food waste biological valorization potential. This differentiation in heavy metal concentration between biological processing outputs is reported to be related to the migration of metals into the food waste fraction from materials such as batteries and ferrous metals that are commonly found in mixed waste. The effect of metal migration to food waste is also dependent on the conditions of waste handling (e.g., size reduction and scraping) and the contact duration between metals and food waste [55]. These conclusions are in line also with Fricke et al. study of 2017 for Germany, where even though a decline has been observed in the content of heavy metals in mixed waste-derived compost since the 1990s onward because of the technological developments, for example, in mechanical biological treatment (MBT) plants, still the quality of compost from separately

TABLE 4 Food Waste Elemental Properties and Sampling Approach in Different Areas. Composition % db Frame

Period/Frequency

Food Waste Originb

Reference

M

–

SS

[46]

M

2 Weeks/daily

Mixed MSW

[61]

H

8 Weeks/daily - weekly

Mixed MSW

[62]

–

–

–

[63]

0.2

H

1 Year/frequent

SS

[67]

2.7

0.2

H

1 Sample

Mixed MSW

[10, 88]

2.4

0.2

H

1 Year/frequent

SS + other organics

[68, 69]

Continent

Country

City

C

America

Canada

Montreal

47.4

Greenland

Sisimiut

49.2

USA

California

46.8

Asia

India

Indore

40.0

Europe

Denmark

Copenhagen

51.3

7.5

2.4

Denmark

Copenhagen

45.5

7.1

Denmark

Aalborg

46.7

6.8

Denmark

Kolding

Denmark

H

Sampling

N

S

2.0 6.9

3.7

0.9

3.2

a

47.5

7.0

2.6

0.2

–

–

–

[70]

46.8

7.1

2.7

0.2

–

–

–

[71, 72]

Finland

Forssa

49.4

2.5

H

1 Sample

SS + other organics

[74]

France

Rennes

42.4

2.1

L

–

SS

[46]

Italy

Lacchiarella

49.0

H

1 Sample

SS

[76]

Italy

Udine

37.6

2.8

M

–

SS

[77]

Italy

Treviso

47.2

2.6

H

1 Sample

SS + other organics

[74]

Italy

Padova

50.2

0.9

H

–

SS + other organics

[80]

43.1

3.5

–

10 Samples

SS

[81]

Spain

5.6

Continued

TABLE 4 Food Waste Elemental Properties and Sampling Approach in Different Areas—cont’d Composition % db Continent

a

Sampling Framea

Period/Frequency

Food Waste Originb

Reference

2.3

H

1 Sample/site

SS

[72, 81]

41.6

2.6

H

1 Sample/site

SS

[72, 82]

Catalonia

39.0

2.6

–

–

SS + other organics

[72]

Sweden

Uppsala

31.5

2.1

–

–

SS + other organics

[72]

Sweden

Uppsala

37.4

2.2

–

–

SS + other organics

[72]

UK

Luton

51.2

6.6

3.1

M

1 Sample

SS

[74]

UK

Eastleigh

48.8

6.4

2.9

H

1 Sample

SS

[74]

UK

Leicester

34.5

4.7

1.6

0.4

H

–

Mixed MSW

[84]

UK

Newtown

47.6

7.0

3.4

0.2

H

–

–

[85]

UK

Wales

49.3

6.5

3.2

1.4

M

Multiple sampling

SS

[85]

Country

City

C

Spain

Catalonia

37.4

Spain

Madrid

Spain

H

N

S

0.2

Diversity of FW producers H, high; M, moderate; L, low. SS: FW source separated; other organics: organic materials such as garden waste, paper, and cardboard other than food waste.

b

2 Food Waste Generation

61

collected biowaste is significantly better [56]. It is hard to identify in literature the exact percentage difference as there are variations in collection methods, building structures, full-scale or limited application of the separate collection scheme, and the types of waste received by treatment facilities, e.g., whether industrial waste are excluded or not. In the study performed on behalf of the Directorate-General for the Environment of the EC, data were collected from different EU counties, indicating that the member states in the beginning of the establishment of separate collection schemes presented 10%–50% higher heavy metal concentrations in compost produced comparing with countries where long-running schemes were applied [57]. Therefore food waste collection method plays an important role for downstream food waste management, and, in particular, separate collection should always be preferred to minimize the contamination risks by toxic substances, such as heavy metals and subsequently obtain end products with the required quality control standards for market uptake.

2.3.4 BROMATOLOGICAL PROPERTIES Bromatological characteristics are related to the properties of food. Since food waste, by terminology, originates from food, a bromatological approach is considered important to examine its nutritional characteristics in terms of carbohydrates, protein, fat and oil, and raw fiber content. Table 5 presents the bromatological properties of sorted food waste for different case studies derived from literature [50]. Despite the limited availability and consistency of data, the high variation in all parameters evidently reflects the complexity and heterogeneity of food waste composition. Total carbohydrates amount to 49.9  9.6% TS, whereas raw fiber composed of lignin, cellulose, and hemicellulose has an average value of 21.1  8.2% TS. These components are resistant to hydrolyzation in the following order lignin > cellulose  hemicellulose. The higher their content in food waste, the lower the biodegradability level of the substrate. Sugars and starch with an average of 10.6.  6.4%TS and 16.0  4.1%TS, respectively, constitute the fractions that are readily available for microbial metabolism since they degrade very easily. However, for the same reason, sugars and starch are highly susceptible to compositional changes along the food waste management chain (i.e., sorting, collection, transportation, and treatment). Fat and oil in food waste originate mainly from animals and vegetables (i.e., dairy products and animal fats) having an average value of 14.5  5.0% TS. Fat and oil in food waste constitute desirable components in anaerobic digestion process since they are easily hydrolyzed, having also increased biogas yield potential [58, 59], whereas Barampouti et al. [50] state that it could also be used as substrate for biodiesel production. Finally the average content of protein is reported at 14.8  4.2%TS. Proteins are easily biodegradable compounds and carriers of nitrogen and sulfur. These elements are connected to bioprocessing management aspects such as ammonia release and hydrogen sulfide formation.

TABLE 5 Food Waste Bromatological Properties and Sampling Approach in Different Areas. % Total Solids (TS)

Sampling

Continent Country City

Fat and Oil Protein

Food Period/ Waste Raw Free Total Fiber Lignin Cellulose Hemicellulose Starch Sugars Carbohydrates Framea Frequency Originb

Reference

Asia

33.5

Europe

India

Indore

8.5

6.8

Turkey

Ankara

24.7

12.6

Denmark Copenhagen 15.9

15.0

15.5

13.4

6.5

Denmark Vejle

10.0

10.0

26.0

13.0

5.0

Denmark Kolding

15.0

15.0

13.0

17.0

Denmark Aalborg

14.1

15.0

14.8

16.1

8.6

Denmark Kolding

15.0

16.0

16.0

12.8

4.9

Denmark Grindsted Denmark

16.5

France

Rennes

Italy

Padova

19.0

16.0

Italy

Udine

5.6

13.4

15.5

9.5 60.0

31.5 14.2

8.5

15.9

4.3

13.3

34.4

2.6

9.9

15.8

21.1

5.0

11.0

5.1

16.0

–

–

[63]

L

–

SS

[66]

H

1 Year/ frequent

SS

[67] [50, 67, 68] [50, 67, 68]

H

SS + other organics

[69]

H

1 Year/ frequent

SS

[68]

H

1 Sample

SS + other organics

[72, 73]

L

–

SS

[46]

57.0

H

5 Samples

SS

[41]

32.2

M

–

SS

[77]

8.2

20.2

1 Year/ frequent

[50, 67, 68]

11.3

14.5

–

a

Italy

Milan

20.7

Spain

Madrid

H

1 Sample

H

1 Sample/ SS site

[72, 82]

UK

Luton

13.5

19.4

M

1 Sample

SS

[74]

UK

Eastleigh

14.3

17.2

H

1 Sample

SS

[50, 74]

UK

Newtown

16.6

25.8

49.8

–

–

–

[85]

UK

Wales

21.4

16.0

56.3

M

Multiple sampling

SS

[87]

Greece

Athens

9.2

10.0

6.3

3.2

11.1

26.0

10.0

50.3

M


/twice per week

SS

[89]

Greece

Athens

11.0

5.0

11.0

3.0

16.0

21.0

43.0

M


/twice per week

SS

[90]

16.3

6.5

10.3

3.9

12.4

1.8

5.5

4.2

Diversity of FW producers H, high; M, moderate; L, low. SS: FW source separated; other organics: organic materials such as garden waste, paper, and cardboard other than food waste.

b

SS + other organics

[78]

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Food Waste Generation and Collection

3 FOOD WASTE COLLECTION 3.1 Factors Influencing Planning and Implementation of Food Waste Collection Systems A separate collection system for food waste is crucial for moving toward circular economy city models, given that the biowaste stream usually holds a significant fraction of total MSW mass (i.e., 20%–60%) [91]. Separate collection of food waste is a well-established good practice for local/regional authorities to meet the legislative targets concerning the diversion of biodegradable waste from landfill and the improvement of recycling rates [92]. Engaging all the involved stakeholders when planning, implementing, and monitoring a food waste management system can ensure high performance of the system [93]. When it comes to the planning of a food waste separate collection scheme, there are many factors that need to be taken into consideration, which will eventually affect the success of the scheme’s implementation and performance. Six type of factors were found to play the main role [88, 92, 94–98]: • Legislation: Binding targets for separate collection of biowaste in local, national, or wider regional levels are needed to push the transition toward recovery and recycling of food waste. An example of such a policy is the new EU Directive 851/2018 according to which member states are obliged from 2023 to ensure that all biowaste produced is either separately collected or composted on site. This ambitious and binding target shall affect the status of several EU countries that will need to adapt to the new framework and phase out gradually collection and treatment practices based on mixed municipal waste. • Food waste availability and expected yields: Reliable data on food waste production and characteristics are considered to be a baseline when planning a collection scheme. Furthermore, producers’ profile along with seasonality features are essential issues that need to be taken into consideration. This will facilitate the choice of collection method and infrastructure for the implementation of the scheme. • Type and capacity of existing or future treatment facilities: Separate collection of food waste aims, among other things, in the valorization of the specific stream for energy and material production. It is important to examine the existing treatment facilities and possible end markets as this can provide crucial information on the amount and quality of the food waste that needs to be separately collected. Subsequently, this also affects both the collection method and the infrastructure used. • Area characteristics: Spatial, demographic, climate, and economic characteristics of the target area need to be considered when planning a separate collection scheme. Is it a rural or an urban area? What are the climate conditions throughout the year? What is the density of the urban fabric and is seasonality (e.g., tourist destination) an issue that should be considered? The area characteristics provide valuable information for the selection of the separate collection method, infrastructure, and awareness campaigns.

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Political and social acceptability: Although legislation sets the targets and timelines and specifies suitable treatment for recycling and recovery, an effective food waste collection scheme also relies on the active public involvement and political commitment. These are undoubtedly factors responsible for the success of a food waste management system. • Cost: The cost of a separate collection scheme is affected by various parameters such as the equipment used and working staff required, the frequency of the applied service, and the information campaigns conducted. Cost effectiveness of such a scheme needs to be considered through a broader perspective including capture rates achieved along with the economic benefits from decreased collection needs for mixed waste, landfill diversion, and potential economic value of end products, if there is an established market. Political commitment is found to be more important than the availability of financing in contributing to sustainable modernization of food waste management [93]. Moreover, involving all the interested parties when designing, implementing, and monitoring changes of a system can ensure the best-functioning food waste systems [99]. The factors that can influence the planning of a scheme for the separate collection of food waste are presented in Fig. 6, along with the involved •

FIG. 6 Factors affecting the planning of food waste separate collection scheme. Source: Authors’ own elaboration.

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Food Waste Generation and Collection

interactions and interdependencies between the key elements of such a scheme. Monitoring activities are essential to provide feedback on the efficiency of the several components of the food waste management scheme so as to redesign and improve the implementation of the different steps.

3.2 Current State of Food Waste Collection Systems Food waste collection is a critical stage of the full management chain, which is regularly undervalued compared with treatment stage [100, 101]. Collection comprises the stage, where the producer (household, business, etc.) and the applied management scheme “meet” [91]. Collection and transport is labor intensive, requires human and capital resources, involves high fuel and energy costs, and is usually considered the most expensive element (more than 70%) of total MSW management costs [102, 103]. Food waste collection from households and public areas is often a responsibility burdening the local authorities; however, it can also be an operation activity of private companies or an operation deriving from public–private partnerships (PPP) [104]. Across the world, local authorities and waste management operators are implementing different food waste collection systems, determined by the existing operational waste collection system, expected yields, available funds, existing local/regional treatment facilities, targeted end product, social acceptance, and political will [92]. A well-designed plan, tailored to the needs of the target area, adequate dissemination and publicity, and the proper implementation of an optimized collection scheme can tackle operational problems and reduce environmental and financial costs [105–107]. This section outlines the different options, collection methods, required equipment, and other relevant components of food waste collection schemes, applied currently. Certain useful definitions are provided as follows: • Participation rate: number of households that participate in source separation/total number of households. • Capture rate: tonnes of targeted food waste material collected/tonnes of targeted food waste material available. • Diversion rate: tonnes of materials diverted from disposal/tonnes of waste produced. • Green waste collection scheme: scheme applied for the collection of green and garden waste from households and public green areas. Collection is performed by municipal services or private companies. Such separate collection schemes contribute to the reduction of biodegradable waste going to landfills. They can run alone (single stream) or in combination with a food waste collection scheme (multistream).

3.2.1 NUMBER OF STREAMS TARGETED FOR COLLECTION A basic planning consideration is the number of waste material types targeted by the applied management system for source separation, collection, and recovery from households or, in general, from their sources of generation. The planning

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essentially depends on the downstream food waste treatment method [108]. Food waste collection systems are distinguished as follows: • Separate collection of a single waste stream (e.g., only food waste). • Separate collection of at least two types of target materials (e.g., food waste combined with green waste). For single-stream collection, food waste is a source separated in specially designed containers. The design of the containers should be in such a way as to facilitate the temporary storage of the target material and, at the same time, to prevent the contamination of the material with other MSW fractions. Singlestream collection schemes can target food waste, including or excluding meat and fish products. In the literature, there are cases that municipalities implement collection schemes, where meat, fish, and cooked food products are not allowed to be disposed of in the bins [109]. For this restriction the public should be properly informed by the operators how to separate food waste at source, while it is also important to the collection bins to bear a clear indication for “no meat and fish disposal.” In terms of convenience of citizens, it is easier to collect all food waste including animal-originated products and cooked foods, on the condition that the receiving treatment facility is compliant with the Animal By-Products Regulation (ABPR) [94]. The collected food waste can be further handled, transported, and treated depending on the existing decentralized/centralized treatment facilities, whether private or not, and the available local markets of end products [92]. For multistream collection, target biowaste streams are separated at source in two or more streams, using different temporary storage media. Targeted biowaste may be collected jointly in a container, distinctive from the one used for mixed waste, or may be collected using more than two containers. The decisive factor of mixing two or more target organics in a container usually depends on the treatment methods used after their collection. If composting is the subsequent treatment method, green waste can also be included in the collection scheme. The drawback of a joint collection of organics lies in the fact that higher-capacity containers are required [108]. In this case the rate of households with yards and seasonal variations of green waste generation is an important planning aspects that should not be neglected [110]. Several studies indicate that separate collection of food waste can potentially be very cost-effective. Especially as the capture rates increase, collection costs might slightly increase, but downstream treatment and disposal costs can significantly be reduced, affecting positively the overall management costs, as well as greenhouse gas impacts [111–113]. Ricci’s research [114] supports that it is preferable to implement a user-friendly separate collection scheme only for food waste and a separate scheme for green waste, as their operation has different requirements and the latter is less demanding in terms of personnel and equipment needs, while green waste is also affected by seasonality. The findings of the Friends of Earth’ report [115] on “Food waste collections – Briefing” supported also this practice, as it is an environmentally and financially preferable choice, and concluded that participation rates in single-stream schemes can be

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higher than in mixed food and green waste collection. Eunomia’s study [116] is in line with earlier suggesting that separate collection of food waste can perform better in terms of expected yields, quality of end products, treatment, and environmental impacts. The research conducted by Bees and Williams [111] in local authorities in England and Wales showed that the areas serviced by a separate food waste collection presented more dedicated citizens in recycling and satisfaction levels on provided services were higher. Brook Lyndhurst’s study [108] observed that higher capture rates are achieved in single-stream schemes, while mixed food and green waste collection demonstrated higher participation rates. Finally, when local authorities implement a separate collection scheme for green waste, free of charge for producers, then it is worth considering how a new food waste collection service could be integrated within the existing system and valorize existing infrastructure (i.e., containers), routing schedules, and information activities to achieve cost savings, even though waste collection vehicles should be appropriate and leakproof to avoid pollution incidents [92]. If a green waste scheme is chargeable, then Eunomia’s study [113] strongly supports that food waste should be excluded. As an alternative the coverage of costs for implementing a separate collection of food waste could be effectively counterbalanced by imposing fees on the collection of garden waste.

3.2.2 COLLECTION METHODS Planning of the food waste collection scheme should ensure easy access for residents/food waste producers and operators and vehicles. The collection method to be selected depends significantly on the type of food waste producer (i.e., food waste from residential, industrial, commercial, and institutional sources). High purity levels are of utmost importance to ensure unproblematic operation of subsequent treatment facilities and high quality of end products. For this reason, comprehensive information and training are required to be provided to the collection staff, food waste producers, and provision of appropriate indoor and outdoor equipment (biobags, kitchen bins, wheeled bins, etc.). More details on equipment are presented in Section 3.2.3.1. The main methods for food waste collection can be distinguished as follows [117–119]: • collection from close to property of food waste producers: door-to-door system, kerbside system; • collection from communal/central points: drop-off or bring-in systems; • collection with a combination of two or more methods. With regard to property-close methods, the door-to-door system could be suitable for sparsely populated areas, where each property houses one to three households. Each household uses a small bin (5–10 L) in the kitchen to facilitate the source separation process, indoors, and then disposes food waste using special bags or higher-capacity bins (30–360 L) outdoors [97, 110, 120, 121]. Collectors pick up the source-separated food waste by entering the household property, e.g., yard of each household. To apply the door-to-door method in densely populated residential areas with high-rise buildings, citizens transfer

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the bags or bins from their apartments into a specially designated area within the building voluntarily assuming this responsibility. Concentrating bags or bins in one place facilitates the work of the personnel of the collection vehicles, which manually or mechanically unload the collected food waste into the vehicle. The application of the door-to-door method requires increased number of vehicle and staff, given the intensive routing needs (i.e., numerous stops, and in case manual loading is needed). Therefore door-to-door collection method implicates higher implementation costs. For a kerbside system, residents/food waste producers are provided with a variety of containers (30, 50, 120, 240, and 360 L) for food waste collection. They are obliged to transfer the source-sorted food waste at the containers installed at the kerbside, close to their property. This system is suitable for single-story dwellings or maisonettes [94]. After the bins are emptied by the collectors, it is the responsibility of the resident/food waste producer to remove the bin from the kerbside back to his/her residence/property. The local authority should provide residents/food waste producers with a precise collection time schedule, based on which food waste will be collected during specific days and time [110]. From the side of operators, ultimate consistency in collection frequency is a fundamental element of door-to-door and kerbside collection systems to create trust and improve participation rates of citizens. From the side of citizens, they should also respect the agreed schedule for collection. The schemes relying on door-to-door collection require more time to be accomplished compared with other methods. Collection time can be improved if food waste is separately collected in bags that are placed out of the houses for collection instead of having collectors emptying bins from each property. Trolleys or wheeled bins may also be used to facilitate and shorten the collection time of individual bags from each floor [94]. In terms of building structure, single-store properties show higher participation rates than multifloor properties. This can be attributed to the fact that residents are reluctant to place out food waste in bags in communal areas of each floor, considering spillage or operators face difficulties in accessing gates/doors of private dwellings [94]. Puig-Ventosa et al. [122] investigated a waste management system in Catalonia, Spain, concluding that the collection of biodegradable waste can exhibit higher purity levels when a door-to-door scheme is implemented. Furthermore, quality checks can be performed easier in property-close systems (i.e., door to door and kerbside) than in drop-off/bring-in systems, as nonappropriate practice of food waste source separation can be identified individually. In those cases the collectors or authorities can provide additional targeted guidance to producers to enhance source separation [97]. On the other hand, drop-off or bring-in systems involve collection of food waste from communal points, using road containers of high capacity (e.g., 660 and 1100L) located at neighborhood level. Local authorities should provide the residents and food waste producers with appropriate indoor equipment (bags and kitchen bins) so as to transport safely the separately collected food waste to the communal points. The residents/food waste producers using special bags have the advantage of being able to dispose separately collected food waste on

70

Food Waste Generation and Collection

their way to work/school etc. and not having to go back to their property to return a bin [94]. It is important to place the communal bins within walking distance from residences. It is also important to consider already established collection points where existing bins for other waste streams (i.e., recyclables and mixed waste) are installed to foster participation since citizens are familiar and comfortable with these sites. The weakness of a drop-off/bring-in system is the lack of personal duty of the producers since there is no direct linking of the household/business and the bin. Therefore lower participation rates are recorded and higher contamination levels are often present [123]. Therefore more frequent cleaning of the containers is needed by the operators [110]. A drop-off/ bring-in system can be implemented using typical, wheeled bins in central collection points, or consider alternative systems, such as underground systems [97]. The implementation of a drop-off/bring-in is suitable for densely populated areas, with limited communal space or high-rise buildings with many apartments [92]. Fig. 7 shows an example of equipment used for a door-to-door food waste collection system, while Fig. 8 shows an example of a drop-off system using central bins [110]. Fig. 9 depicts a close to property scheme for food waste collection from the doorstep of single-family and multifamily residences, while Fig. 10 shows a room of a building dedicated to kerbside collection of food waste from apartments [120, 124]. Fig. 11 includes a drop-off point using a 120 L bin for food waste collection in a remote island community of Greece, installed at the same point where other waste fractions are collected, e.g., recyclables and mixed waste to facilitate convenience of users [124]. The aforementioned collection methods may be combined to achieve higher yields in food waste collection. In particular, to implement a separate

FIG. 7 Examples of (A) kerbside and (B) door-to-door collection system. Reproduced with permission from LIFE Athens Biowaste, Deliverable 6a ‘Guide for the implementation, monitoring and evaluation of bio-waste source separation and composting schemes’. LIFE10 ENV/GR/ 000605—Integrated management of bio-waste in Greece: the case study of Athens, 2014.

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FIG. 8 Drop-off collection system. Reproduced with permission from LIFE Athens Biowaste, Deliverable 6a ‘Guide for the implementation, monitoring and evaluation of bio-waste source separation and composting schemes’. LIFE10 ENV/GR/000605—Integrated management of bio-waste in Greece: the case study of Athens, 2014.

FIG. 9 Door-to-door collection of food waste from single-family (left) or multifamily residences (right). From Authors’ personal photo file.

food waste collection system in areas where there are variations in the population density in the urban fabric, the collection using drop-off can be combined with the door-to-door method. Finally, there are several cases of implementing targeted food waste separate collection programs addressed to large producers of food waste. These types of large producers indicatively refer to airports, army camps, university campuses, school units, prisons, catering/retail services, tourist

72

Food Waste Generation and Collection

FIG. 10 Kerbside collection point for food waste inside a building. Reproduced with permission from S. Lopes, S. Freitas, Separate Collection of Municipal Waste - The example of Lipor, Portugal, TAIEX-EIR PEER 2 PEER Workshop on Waste Management for Greek Cities in Athens-Greece, 2019.

FIG. 11 Drop-off point for food waste collection in a remote island community of Greece. From Authors’ personal photo file.

accommodation facilities that provide catering services, sports venues, shopping centers, manufacturing and processing industries of food products, open farmer markets, etc. By incorporating large producers in a separate food waste collection scheme, higher quantity and quality of source-sorted food is expected, given the homogeneity of these fractions, for example, food processing waste [125, 126]. Homogeneous food waste flows can be more suitable feedstock for effective

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treatment processes [127]. The most efficient collection method to incorporate large producers in a food waste collection scheme is by providing door-to-door services. Quality checks are implemented easier, and the comfort of users is higher [120].

3.2.3 COLLECTION INFRASTRUCTURE—STAFF—FREQUENCY The collection and transportation of food waste produced are crucial stages of a management system as [121, Chapter 4, 128]: • They usually account for almost two-thirds of the total cost of a waste management system. • They are the technical linkage between producers and treatment methods, thus determining the successful valorization of food waste. • They are the organizational linkage between producers and the overall waste management system applied, therefore affecting directly the successful handling of food waste produced. This section provides an overview of the required collection infrastructure (bags, bins, collection vehicles, etc.), personnel, and collection frequency for the implementation of the separate food waste collection systems.

3.2.3.1 Containers Containers for the collection of food waste can be categorized as indoor and outdoor depending on whether or not they can be installed at household level, the kerbside, or another collection point [121, Chapter 4].

Indoor. Indoor containers usually refer to kitchen bins or caddies usually provided to households for the source separation of food waste produced, regardless the collection method applied in a specific area [110]. The typical capacity of kitchen caddies can vary from 5 to 10 liters based on the individual needs of each household, such as the number of family members, available storage space, and esthetics [121, Chapter 4]. In case of commercial and institutional facilities, the capacity of an indoor container can be up to 30–240 liters [97]. Kitchen caddies are usually made of plastic and can be either with or without ventilation, as shown in Fig. 12. Ventilation holes allow the aeration of the food waste collected and thus reduction of odors arising from the decomposition of the organic

FIG. 12 Examples of kitchen caddies both solid and ventilated. Reproduced with permission from LIFE Athens Biowaste, Deliverable 6a ‘Guide for the implementation, monitoring and evaluation of bio-waste source separation and composting schemes’. LIFE10 ENV/GR/000605—Integrated management of bio-waste in Greece: the case study of Athens, 2014.

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material alongside with the reduction of the humidity content. This subsequently leads to the reduction of food waste volume and mass [94]. When a ventilated kitchen caddy is selected, the use of liners is mandatory to avoid the leakage of liquids, while it is also suggested in case a rigid kitchen bin is used to reduce cleaning needs. Kitchen caddies should be designed to facilitate the easy separation of food waste at source, and it is, therefore, recommended that they are wide enough for a plate to be easily emptied and of low depth to be easily cleaned [121, Chapter 4]. Finally, provision of kitchen caddies in households/businesses for free seems to assist their participation in source separation [110].

Outdoor. Outdoor containers refer to containers of larger capacity compared with kitchen caddies, which can be set for collection at the kerbside or at other communal collection points (drop-off or bring-in systems) [121, Chapter 4]. Bins used for kerbside collection of source-separated food waste are usually two wheeled with a capacity ranging from 30 to 360 L, depending on the number of households using the kerbside collection bin, as shown in Fig. 13 [110]. However, smaller collection bins are also available when a kerbside collection system is applied with a capacity lower than 30 L, which usually do not include wheels [94]. In cases where food waste is jointly collected with garden waste, wheeled kerbside bins of increased capacity are preferable, usually 120–240 L, and should be sized based on the collection frequency and the garden size of the specific area served [121, Chapter 4]. Table 6 includes information for calculating required bin capacity per number of households serviced on a kerbside collection system. Concerning large outdoor road containers, attention should be given in cases of manual loading or low vehicle accessibility in ensuring that food waste can be safely removed, as they have increased bulk density (0.5–0.65 t/m3) and subsequently containers can be very heavy [121, Chapter 8]. Outdoor collection bins are recommended to be without ventilation to prevent leachate escaping and be equipped both with a lid and a locker, especially the ones with a capacity lower than 50 liters to avoid contact with animals and loss of material due to overturning [94].

FIG. 13 Bins used for kerbside collection with a capacity of 360, 240, and 120 L, respectively. Reproduced with permission from LIFE Athens Biowaste, Deliverable 6a ‘Guide for the implementation, monitoring and evaluation of bio-waste source separation and composting schemes’. LIFE10 ENV/GR/000605—Integrated management of bio-waste in Greece: the case study of Athens, 2014.

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TABLE 6 Proposed Bin Capacity per Number of Households Serviced on a Kerbside Collection System. Households per Building

Required Capacity (L)

1

35–40

2

35–40  2

4–6

120

7–12

240

>12

360

Source: Data from LIFE Athens Biowaste, Deliverable 6a ‘Guide for the implementation, monitoring and evaluation of bio-waste source separation and composting schemes’. LIFE10 ENV/GR/000605—Integrated management of biowaste in Greece: the case study of Athens, 2014.

Outdoor collection bins set in both drop-off and bring-in collection systems are, in their vast majority, accessible on a 24-h basis for users [110]. This type of bins can also be referred to as communal collection bins since they are designed for and set to a neighborhood level or can have a more centralized character in the framework of waste-recycling centers. Communal bins should always be placed within walking distance or in frequently used routes to assist and encourage citizens’ participation [97]. The aforementioned bin type can be either overground or surface, semiunderground, or fully underground [121, Chapter 4], [97]. The noticeable difference, apart from the level at which the recipient’s capacity is set, between overground and underground collection bins (semi or not), is the complete lack of mobility of the latter [91]. Overground or surface communal collection bins refer to food waste collection bins with a capacity ranging from 260 to 360 L, usually two-wheeled bins, and in some cases, capacity may reach 660 liters or even more (e.g., 1100 L) based on the population density and the collection system design, which are typically four wheeled made from plastic or even metal [110]. Fig. 14 shows a 1100-l bin placed at a central point for food waste collection [124]. In a semiunderground collection bin, a part of the container still remains at the surface, while the rest of it is placed underground, while in a fully underground collection bin, the whole part of the container is placed under the surface. Capacities of commercial bins may range widely, e.g., from 300 L to 5 m3 [91, 97, 128]. Underground collection systems (semi or not) are suitable not only for old, historical cities with narrow streets but also for urban areas with high population density and limited free space or regions that experience high temperatures [121, Chapter 4], [129, 130]. Semiunderground containers are usually cylindrical tanks made of plastic (polyethylene) and can be equipped with an inner reinforced bag along with a leachate collection system. A fully underground food waste collection system consists of inlets that are placed above ground and a container, which allows the collection both of the food waste

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FIG. 14 Central food waste collection point with 1100 L-capacity bin. From Authors’ personal photo file.

and the leachate produced [128]. Fig. 15 presents an underground systems placed in public spaces within a Greek Municipality [124]. However, special care should be taken when planning the food waste collection system using central road bins or underground containers, since food waste disposal is performed anonymously. If a bin is not linked with a specific producer, i.e., household or business, then the ownership and responsibility of producers are not enhanced. Placing locks that open using a key or a magnetic

FIG. 15 Underground bins for separate collection of municipal waste installed in a Greek Municipality. From Authors’ personal photo file.

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card and regularly monitoring the quality of food waste collected can identify problems early and intensify communication activities for citizens, whenever considered appropriate [131]. A locking mechanism for bins can also stop pests and prevent odor nuisances [109].

Bulking Containers. Bulking facilities are used as an intermediate stage for the temporary storage of smaller food waste loads before reaching the final treatment facilities, mainly when long distances are involved [121, Chapter 7]. For bulking facilities, skips and containers are used for tipping the collected food waste, while in some cases the transfer of food waste from vehicle to vehicle can also be used [97]. Storage capacity of bulking containers should be adequate to meet the needs of food waste produced taking into account fluctuations due to seasonality and permissible storage time. Containers’ capacity can vary from 2 to 12 m3, and therefore they are not suitable for manual handling but for being emptied into a collection and transport vehicle. Containers with a capacity greater than 12 m3 should be individually transferred to the food waste treatment facility. Bulking containers can be either open or closed, in which case they are equipped with a hydraulic or sliding roof [121, Chapter 4]. Sliding roof containers are not suitable for vehicles equipped with side loading, but their main advantage is that they can be loaded from above allowing the use of greater size containers, thus maximizing total load. Finally, setting and operating bulking facilities should aim in maximizing the effectiveness of the collection scheme applied, along with benefiting from the reduction of environmental and financial impacts for a specific area [121, Chapter 7]. Special Collection Systems. Vacuum Collection Systems. Vacuum collection systems refer to an underground network of pipes properly adjusted to buildings and/or communal collection points through which waste is carried using a flow of air from the generation source to a storage container [128–130, 132]. Vacuum collection systems can be used for the collection of both one waste stream and separated waste streams, in which case, multiple inlets must be provided [121, Chapter 4, 128, 132]. Additionally, vacuum collection systems can be either mobile or stationary with regard to the type of container used, while they both follow the same operating principle for refuse and transportation of waste through a wide pipeline network [128, 132]. Stationary vacuum systems are equipped with a stationary container for temporary storage that can usually hold up to 10–12 tonnes, while in case of mobile vacuum systems, waste is directly transferred through the pipes to a collection vehicle [97]. Using vacuum systems instead of vehicles for the collection of waste goes back in 1970s applied mainly for hospitals and high-rise residential areas [121, Chapter 4], [130, 133]. Nowadays, pneumatic waste collection systems become more and more popular, especially in congested urban areas and cities with historical centers, where various limitations arise, such as restrictions for land use, [129]. The main advantages of vacuum collection systems are the reduction of noise and esthetic pollution, the reduction of odors escaping, and the reduction

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of manual work required [133]. However, these pneumatic systems show increased capital costs [130]. An individualized cost analysis should be made for a specific area to assess the feasibility of such a system [121, Chapter 4], [128]. Moreover, since they use electric power for their continuous operation, it is questionable if they could be sustainable at a global level due to their high demand for electricity [129]. Kitchen Grinders. An alternative scenario for diverting produced food waste from landfills is the use of food waste disposers and can be a combined approach for managing food waste and wastewater. Up to now a food waste disposer system is a usual practice in the United States of America, while it is also applied in a number of other countries such as Canada, Australia, New Zealand, Brazil, and Japan. However it seems that in Europe this approach is not very popular [134, 135]. This alternative system consists of grinders installed in kitchen sinks. Grinded food waste end up to a settling tank, where the supernatant is used as input for wastewater treatment plants and the remaining sludge is used as feedstock for anaerobic digestion [136]. Across the globe, there are countries that allow the use of the central sewage line for disposing of grinded food waste. However, this method requires adequate sizing of the sewerage system to avoid clogging [128]. With regard to waste disposers, the main issues and doubts raised are related to the implementation impact of such a system to the levels of water consumption, the greenhouse gas emissions, the efficiency of wastewater treatment facilities due to fluctuating characteristics of wastewater, and potential damages to the sewerage system. Nevertheless, it is mentioned that with a proper design, both a sewerage system and wastewater treatment plants can efficiently treat the products of this process [134, 135]. Household-Scale Drying Systems. An alternative management option for food waste produced at households involves drying of sorted food waste at source through the use of an innovative household food waste dryer that transforms input material into high-quality dried biomass. In the literature, there are various systems referenced, for example, commercial, such as Smart Cara CS10, LOOFEN, Coway, Samoh NK, Duo Enterprise Ltd., and the prototype DRYWASTE household waste drying system that was developed and demonstrated in the framework of the LIFE Drywaste project [137, 138] (see Fig. 16).

FIG. 16 A Smart Cara house dryer, B. LOOFEN house dryer, and C. prototype LIFE Drywaste system for food waste collection. From Authors’ personal photo file.

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These systems have various technical characteristics including 5–15 L capacity, operation temperature 60–100°C, and energy consumption ranging between 0.25 and 0.7 kWh per hour. It is very common to have a deodorization system consisted of activated carbon filters to tackle with odor nuisances. This novel drying technique removes a large proportion of the moisture contained in sorted food waste, reduces its mass and volume drastically by 70%–78% and 58%– 82%, respectively, and produces a biologically stabilized and odorless biomass that can be used as renewable energy source for bioenergy production [137]. The produced stabilized dried biomass can be easily stored in the house, even for weeks, without causing discomfort to users and be collected less regularly than fresh food waste. The produced biomass has increased flexibility in terms of final application potential since it can be used as feedstock in anaerobic digestion plants for biogas production, in dedicated incineration plants for energy recovery, in industrial facilities for lowering their carbon footprint, and other uses [139]. Regarding investment costs, since these systems are electric devices, they have high capital costs, i.e., 100–200 euros per unit, comparing with a conventional household bin of 10 L capacity costing approx. 10 euros per unit [137]. However, this alternative system can be an attractive solution, easily integrated to existing or future waste management strategies and plans, for areas with warmer climates where higher decomposition rates of the organic matter prevail, leading to numerous drawbacks in terms of sustainable management (i.e., increased frequency of waste collection routes, nuisance due to odors, handling problems, and safety and health issues).

3.2.3.2 Bags or Liners In several schemes, food waste is separated at source (i.e., household and business) using a liner that is placed inside the indoor equipment, usually consisted of kitchen caddies or bins. The liner refers to a bag made from compostable material, such as potato or cornstarch or other biobased sources, or paper [94] (see Fig. 17). In addition, liners can be also made from polyethylene (PE), which is nonbiodegradable, and are only recommended for treating collected food waste in anaerobic digestion facilities equipped with the appropriate depackaging and postdigestion screening Schemes [121, Chapter 4]. Liner size should

FIG. 17 Compostable bags (A,B,C: starch-based bags, D: paper bag). From Authors’ personal photo file.

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fit the kitchen caddie used and be thick enough to handle the weight of the produced food waste [110]. Starch liners are usually 16 μm thick, while paper liners are about 1 ply and polyethylene liners about 7–10 μm thick [121, Chapter 4]. The biodegradable/compostable bags chosen for separation at source of food waste must be compliant with the international standards EN 13432 (or ASTM D6400) and EN 14995 (or ISO 17088) [110]. It is important to ensure the use of 100% compostable bags when residents/waste producers separate at source food waste because these bags do not interfere with the biological treatment processes following the collection and transport step and ensure the quality of organic feedstock and end products. On the contrary, common plastic bags require additional resources for removal, and once mixed and processed with the organic substrate, it is difficult to be removed and thus affects the purity level of end products. There are many commercialized biobags available in the market [140–143] in various sizes and thickness, which are turned completely into carbon dioxide, water, and organic matter within a period of 3–6 months and have adequate mechanical properties to prevent spilling of liquids discharged from food waste [94]. It is preferable to use liners since they can ensure a cleaner process both for residents and the collection crew, thus making the scheme more attractive to use [121, Chapter 4]. For starters, using liners reduces the need for cleaning the caddies, and if used in combination with vented caddies, odors can also be reduced. This way, more households can be encouraged to apply source separation of food waste. Furthermore, by using liners, not only food waste does not stick inside the external containers but also the risk of potential leakages are reduced, thus keeping them cleaner and making it easier to empty them [94]. Alternatives for the separation of food waste, other than compostable bags, can be the use of paper bags as the ones used in grocery stores and newspapers for wrapping the food waste before the disposal to the kitchen caddy [110]. Many schemes concerning the source separation of food waste provide liners for free at the beginning of the implementation. Apart from being distributed to the residents for free, liners can be provided to residents through purchasing from local authorities or private suppliers [121, Chapter 8]. However, liner provision is associated with an increased cost both for households, in case they purchase them, and for local authorities, in case of free distribution. This issue steered a new approach on liner provision in the United Kingdom, where residents are encouraged to reuse carrier bags for shopping that are made of compostable starch as liners for the source separation of their food waste [121, Chapter 8].

3.2.3.3 Collection Vehicles Implementing a food waste management scheme aims at collecting waste not only in a safe but also in an efficient way, ensuring public health and societal needs. There are various factors to consider when choosing collection vehicles for food waste [121, Chapter 5], [91]: • Will the specific waste stream be collected separately or along with other streams?

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•

What are the existing collection systems for other waste streams and the existing vehicle fleet? • In what type of treatment will the collected food waste be subjected to? • What are the spatial, demographic, and property-type characteristics of the area to be served? • Which are the health and safety requirements to be taken into consideration? • What will be the cost of purchasing, operating, and maintaining the vehicle fleet? There are tailor-made vehicles constructed for the separate collection of food waste, but there also are vehicles designed with multiple compartments for the combined collection of food waste with other waste streams, such as recyclables, green waste, and/or residual waste. In this way the number of collection vehicles needed for a specific area is reduced. However, a major disadvantage of collection vehicles with multiple compartments is that once a compartment is full, the collection must stop and return to unload the collected quantities. In all cases the requirements, arising from the EU Regulation on animal by-products (1069/2009), must be fulfilled regarding the cleaning and disinfection of vehicles (including food waste containers) used for collecting mixed food waste including food types such as raw meat and fish products and egg products. Other parameters that should also be taken into consideration for the selection of appropriate vehicles are the following:

Capacity. The collection vehicles must have adequate capacity for both the volume and the tonnage of food waste collected daily [121, Chapter 5]. Suitable planning for the needed capacity of collection vehicles assists in minimizing the number of collection routes. Due to the increased specific volume of food waste, the weight of collected food waste must be monitored to prevent overloading and subsequent problems of vehicles’ operation [110]. Compaction Level and Prevention of Leakage. Compaction of sorted food waste is not recommended since the increased density does not allow high compaction levels to be achieved. Neither milling-type nor pressing-type vehicles are suitable for food waste collection. Application of compaction would cause the production of leachate due to the increased moisture content [121, Chapter 5]. Moreover, once food waste is compacted, it will be difficult to remove impurities. A closed, watertight lorry with relevant mechanical strength for the lifting mechanism is adequate. Alternatively, according to White et al. study, it is stated that collecting paper with food waste may reduce leachate production [144]. However, the latter can have a negative effect on the treatment process and especially during anaerobic digestion [145]. Including paper waste is neither the optimum solution for composting, as it is then downgraded, considering the value it has in the recycling market, regardless the fluctuations. Lifting Mechanism and Loading Points. Food waste collection vehicles can show multiple variations with respect to the type of the vehicle’s loading type

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(lifting system and loading points) and main body characteristics (type and size). A brief summary of the main characteristics of vehicles used for the food waste collection follows. Loading type: Loading refers to the lifting mechanism, as well as the loading points used in a collection vehicle. Concerning the lifting system, a collection vehicle can be equipped with a crane, a hook lift, an automated lift, an automated arm, or even no lifting mechanism [91]. Collection vehicles that combine both a bin lifting mechanism and manual loading from collection personnel are considered to be more effective, especially when door-to-door collection is applied [110]. Concerning loading points, food waste collection vehicles can be rear, side, or front loading [132]. Side- and front-loading collection vehicles are usually semiautomatic, operated by the driver alone. Rear-loading vehicles are the most commonly used vehicles regarding food waste collection. This type of vehicles seems to be very efficient especially in urban areas, where narrow streets and parked cars can be the major obstacle for side- and front-loading vehicles. Although front-loading vehicles can be fast enough while loading, emptying, and unloading it appears that maneuvering into the appropriate position can be more time consuming. The use of side- and front-loading vehicles can reduce the operational cost of food waste collection, as less staff is needed; however, the investment cost is much higher compared with rear-loading vehicles due to diversification of equipment used [128, 132]. Considering the loading process, special attention should be given in avoiding uneven distribution of weight over the main body of the vehicle [121, Chapter 5]. Unloading of the collection vehicles should occur either in an intermediate bulking point or directly in the treatment facilities [94]. In addition, particular attention should also be placed on the health and safety of the working staff, as they have to work on the road and manage food waste bins that may be heavy [132]. Main body type: A food waste collection vehicle can be either open or closed [91]. Additionally, the main body of collection vehicles can be of one chamber or multichamber [121, Chapter 5, 128, 132]. Rear-loading vehicle body is usually of one chamber, while side- and front-loading vehicles can have multicompartment bodies [132]. The gross vehicle weight can vary from 7.5 to 25 tonnes, depending on the collection scheme applied [121, Chapter 5]; however, very large capacities are not recommended for source-separated fractions [110]. In cases of historical centers, congested areas or areas where heavy vehicles are forbidden, the use of smaller collection vehicles with a capacity not greater than 2–3 m3 can be implemented. These vehicles have an open body and can act as complementary satellite units to the main collection fleet of a specific area [128]. It is of great importance that in all cases, no matter the type of equipment used, special attention should be given when selecting collection vehicles to ensure that the requirements of health and safety, both for the crew and the population served, are met.

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FIG. 18 High-capacity vehicle for food waste collection from urban, densely populated areas. Reproduced with permission from LIFE Athens Biowaste, Deliverable 6a ‘Guide for the implementation, monitoring and evaluation of bio-waste source separation and composting schemes’. LIFE10 ENV/GR/000605—Integrated management of bio-waste in Greece: the case study of Athens, 2014.

FIG. 19 Small-capacity vehicles for food waste collection from sparely populated areas: (A) mechanical loading from rear and (B) manual loading from side. From Authors’ personal photo file.

Figs. 18 and 19 include high- and smaller-capacity vehicles used for food waste collection in densely populated and sparsely populated areas, respectively. Bearing a logo that publicizes the collection of food waste facilitates the dissemination of the scheme applied within an area, as shown in Fig. 20 [124].

3.2.3.4 Staff/Personnel Involved in Food Waste Collection The human resources needed to perform collection rounds are a critical aspect of planning an efficient food waste collection scheme. The number of the collection staff employed is directly related to the operation costs of the scheme, since

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FIG. 20 Collection vehicle for biowaste with brown bins used in Athens municipality, Greece. From Authors’ personal photo file.

the salaries constitute a major category of expenditures. Appropriate planning for determining the number of staff required can ensure higher-performance levels of the applied scheme. Local authorities or private operators running food waste collection services should also aim at the safety, health, and welfare of collection staff from the early stages of the planning process [121, Chapter 12]. According to WRAP study [94], it is recommended for the waste operators, public or private, to perform interviews for staff selection to ensure dedicated personnel with a real interest in their role. Appropriate and comprehensive training on operation procedures should be provided to the collection staff from collection routes within the city to the final food waste treatment facilities, such as good hygiene practices, use of personal protective equipment (PPE), speed of operations and driving times, and mapping of specific implications within the collection area (i.e., steep slopes, uneven floor, steps, and narrow alleys). Staff should be also informed on related risks, such as the difficulties in accessing the containers, damages of equipment, and varying weight of containers needed to be lifted repeatedly if manual collection and unloading are practiced [121, Chapter 12]. By providing correct training to the collection staff, then the personnel can also provide guidance to food waste producers, if inappropriate sorting of materials is observed during collection rounds. Visual check is important to be performed by collection staff to prevent contamination of the vehicle by unwanted materials. Personal communication or informative stickers or tags (Fig. 21), warning about wrong sorting of materials and justifying why the container was not collected, can have a positive effect on reducing such problems, as the tag used by the Compost and Biogas Association of Austria [146].

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FIG. 21 Informative tag put on the container to warn food waste producers on correct/ wrong sorting of materials. Reproduced with permission from S. Uschnig, F. Amlinger, The Compost & Biogas Association—Austria (presentation), International Study Tour BIOWASTE, Austria, 15–20 September 2019, p. 6.

The number of persons making up a collection crew is linked to the needs of the collection scheme applied and the equipment used. A minimum of a twoperson crew per vehicle is usually considered, consisting of one driver and one person for loading and unloading. Additional staff might be needed in cases where collection takes place from both sides of the road or food waste is collected along with other waste streams, e.g., recyclables [147].

3.2.3.5 Collection Frequency Practice and experience have shown that there is no one-size-fits-all, best system for food waste collection that can be implemented efficiently in all cases.

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Consequently, collection frequency is a crucial aspect for waste planners and managers that is directly related with the type (e.g., door-to-door service, kerbside collection, and bring schemes with road containers) and conditions (e.g., voluntary/mandatory nature and economic instruments) of collection system applied. The frequency of food waste collection should be planned and implemented considering also the type of activity or user (i.e., commercial, institutional, and domestic) and the characteristics of the area (urban, rural, remote, etc.) targeted [144]. Single-family households, multiple flat buildings and businesses in densely populated areas, or remote settlements, certainly, have different needs [98]. Furthermore the variety of climatic conditions across regions poses different requirements. For example, warmer climates, such as the Mediterranean region, require 2–3 times per week or daily collection frequency from households and/or restaurants and high touristic areas, while in cold climates, such as Slovenia, the United Kingdom, and Northern Italy, food waste collection may be performed on a fortnight basis [148, 149]. With increased collection frequency, smaller capacities of bins can be used, which may be more comfortable when food waste producers have to carry their bins at kerbside or central road level. An additional point related to the collection frequency is the reliability aspect. The food waste scheme operators should avoid many variations in the collection program so that householders and businesses are aware of the exact dates and times of collection. Minor modifications to collection frequency can happen, e.g., during public holidays, as long as citizens are informed well in advance. Otherwise, high fluctuations in the collection services provided can cause discomfort and loss of trust in the food waste management Scheme [95]. Following, certain, indicative, examples of different cities implementing separate collection schemes for food waste are presented, along with their results achieved. The cities are at a different stage of maturity of the schemes applied: some are at beginner’s level; others have been through decades of gradual development of the schemes; the systems may be voluntary or mandatory with economic instruments in place. For all cities, the utmost objective of the separate collection of food waste is the reduction of the residual waste and increase of overall recycling rates. In Parma (IT), food waste collection is a mandatory door-to-door Scheme. A 12% discount on municipal fees is applied to householders that practice home composting. For recyclables and residual waste, collection is performed using kerbside collection in combination with pay as you throw (volume-based and frequency waste fees) that started since 2012 and developed gradually across the whole city by 2015. In restaurants and bars located in the touristic area of the city, food waste collection is a daily operation, while for specific large producers, there is even a special condition for collection two times per day. For domestic users the frequency of food waste collection is two times per week, whereas for residences in the historical city center, food waste is collected three times per week. The use of ventilated bins and biodegradable bags that are distributed for free at yearly basis is mandatory. Overall the aforementioned system applied in the city resulted in 90% diversion of food waste with 97% purity level

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of separately collected food waste that contributes to the production of highquality compost and biogas [150]. In Porto (PT), separate collection of food waste is implemented since 2005. The scheme includes several initiatives for large producers (HORECA sector, food industry, retailers, open markets, etc.) where food waste is collected using door-to-door services, three times per week or daily. Operators enter the properties of large producers and check the quality of source-sorted material prior to collection. Food waste is source separated and preserved in 50–240 L bins in specially designated rooms that are often refrigerated for hygiene reasons. These special rooms for food waste storage are a prerequisite for obtaining a government-issued license/permit to operate. Impurities observed are lower than 6%. For households a door-to-door collection scheme is in place, using 10, 40 (single houses), and 140 L (multiapartments) bins. The collection frequency has been set at two or three times per week. Composting is the main treatment option, combined with community-scale and home-scale composting projects [120]. In the city of Vrilissia (EL), food waste collection has been recently introduced, since 2016, and is performed six times per week from road containers targeting residences and commercial properties. Moreover, food waste collection is performed during the open farmer markets that are organized weekly in different neighborhoods of the city. Open farmer markets are very common in Greek cities, and they constitute large food waste producers. Until now, citizens participate to the scheme on a voluntary basis. The first years of implementation (between 2016 and 2018) resulted in 5% separate collection of food waste, 7% separate collection of green waste, 14% of packaging waste, and thus 26% diversion from landfilling. The economic savings for citizens in terms of municipal taxes reached 25% within this period. Therefore, currently, the municipal authorities are envisaging the pilot implementation of door-to-door services and preparing a pay-as-you-throw strategy, including locking the road bins and weighing residual waste [151].

3.2.4 COST CONSIDERATIONS It is difficult to provide a universal calculation for food waste collection schemes with precise costs per tonne or costs per household, since different conditions (e.g., existing waste management schemes, available treatment and disposal infrastructure, legislation, and economic tools employed) apply in each municipal authority. The following cost aspects should be taken into consideration for developing a comprehensive basis for cost calculations [92, 94, 110]:

3.2.4.1 Investment Cost Categories These cost categories are related to initial, capital expenses for the organization and setup of a separate collection system for food waste, such as the following: - Cost for purchase of appropriate bins for food waste collection (i.e. indoor and outdoor equipment).

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Food Waste Generation and Collection Cost for purchase of a special food waste collection vehicle or cost for modifying an existing, conventional vehicle to collect food waste. The possibility of leasing the equipment may be also considered. Cost for biodegradable, compostable bags supply (e.g., starch based or paper based). This cost category may be considered for a yearly basis if bags are offered for free by the local authority to users or just for the initial phase of the scheme, e.g., first 3 months.

3.2.4.2 Operation and Maintenance Cost Categories The main cost categories involved in the operation and maintenance of a separate collection scheme for food waste are as follows: - Number of personnel needed for collection rounds (drivers and crew). - Local wages for personnel involved in collection and maintenance. - Costs for maintenance, insurance, and operation of collection vehicles. - Fuel costs. - Cost for replacing damaged bins (5% on annual basis). - Cost for additional, supporting personnel for awareness campaigns on source separation. For this activity, existing local and other voluntary groups working on the same topics (e.g., environment, recycling, and composting) may also be involved to support the awareness activities of the local authority for food waste collection, thus lowering expenses. - Cost for developing information materials and implementing awareness campaigns to different targets groups, for example, households, schools, and local business owners. This cost category may be higher during the initiation of the scheme in the first year and lower in the next years to continue disseminating the food waste collection services and maintain engagement and active participation of citizens. Additional aspects that affect the cost of a food waste collection scheme are the following: - organization of routing and collection frequency within the different neighborhoods of the local authority, - target set for capture rates and diversion achieved, - requirements for monitoring the scheme performance. Regarding the initial phase of the separate collection scheme, the investment cost for the purchase of the necessary equipment will be high. If a door-to-door collection system is chosen, the cost for bins’ supply will be higher than that of a central bin collection system. However, the investment fees can be reduced when existing indoor or outdoor bins are used or conventional collection vehicles are allocated and modified for food waste collection. The cost can be further reduced when biodegradable bags are not supplied for free to citizens. Biodegradable bags are highly priced consumable goods that are required to be replaced, even on a daily basis, for the source separation of food waste produced, increasing significantly the cost for authorities. Nevertheless, in cases where no free distribution takes place, care should be given to provide citizens

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with alternative options or inform them from which local stores they can purchase biodegradable bags. In general the greater the area of the scheme implementation, the lower the investment cost per resident will be [94, 110]. If a food waste collection scheme is properly designed and implemented, involving adequate awareness and information activities for citizens and transparent procedures, then better participation levels can be expected, making the scheme more cost-effective. At large the cost for collection personnel holds the greatest share of operation costs, followed by fuel and maintenance costs, and expenses for insurance and running of vehicles. Consequently, food waste collection should be continuously monitored and rescheduled (e.g., routing, frequency, and personnel per round) aiming to increase cost savings. The costs for mixed waste collection should also be taken into account [120]. Eunomia [152] and ACR + [153] studies revealed that additional costs incurring due to the introduction of separate collection schemes can be offset by decreasing the collection frequency for mixed waste. Nevertheless, despite the costs arising for the implementation of separate collection for food waste, notable savings are incurred, which can be used for sustaining the applied collection scheme. Diverting food waste from landfills may reduce costs for landfill taxes and gate fees and prevent fines for not meeting recycling or landfill targets [92]. High costs for landfill disposal can be a significant driver for setting separate food waste collection schemes; however, this is not the case for countries that landfilling is still considered a cheaper option.

3.3 Monitoring and Evaluating Food Waste Collection Schemes Monitoring refers to the regular measurement of several parameters related to a scheme applied to record its progress, while evaluation refers to concluding on how well this scheme performs through a critical analysis of the monitoring data obtained. Indicators are tools that allow monitoring data obtained to be converted into meaningful information, thus measuring the achievements and the effectiveness of the scheme applied [154–159]. An indicator is “a parameter, or a value derived from parameters, which points to, provides information about, describes the state of a phenomenon/environment/area, with a significance extending beyond that directly associated with a parameter value” [160]. Setting aims and objectives is a sine qua non for the monitoring and evaluation of a food waste scheme applied since they allow to create a consistent monitoring and evaluation framework. The SMART objectives concept was introduced by Peter Drucker in 1954 arguing that targets and objectives need to be Specific, Measurable, Appropriate, Realistic, and Timed. Nowadays, slightly altered from the Drucker’s concept, SMART is a very common acronym used to set objectives and is analyzed as follows [159]: • Specific, objectives must be easy to understand with a minimum or low level of ambiguity.

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Measurable, an objective that can be measured not only by a theoretical approach but also in practice. • Achievable, is it possible for the objective to be achieved? • Relevant, is the objective related to the initial aim? Is it going to help in achieving the original aim? • Time bounded, an objective needs to have a time limit. Up to now, there is no universally accepted monitoring framework regarding food waste management using specific indicators. However, monitoring of food waste collection schemes can follow the patterns of other separately collected MSW fractions such as packaging waste materials. There are various studies using different sets of indicators, covering a wide range of waste streams [158, 161–165]. Following, selective sets of monitoring indicators for waste management schemes are presented that either refer to food waste management alone or can be adapted to fit the characteristics of such a concept. In Table 7, indicators for monitoring waste collection schemes are presented, which can be easily adapted for a food waste collection scheme. Table 8 includes indicators for monitoring food waste management schemes in the context of food policy. In Table 9, monitoring indicators are presented under the context of environmental sustainability that includes, among others, food loss and waste reduction. •

TABLE 7 Selective Key Performance Indicators (KPI) Used to Monitor Waste Collection Schemes That Could Be Adapted for Food Waste. Aim

Objective

KPIs

Monitoring the recycling collections

Measuring the amount of the food waste collected over a period or against a baseline

Tonnages kg per household per period of time out of all the households served by the scheme(s)

Measuring the change in recycling rate (for a particular area)

% recycled food waste

Measuring capture rates for food waste over a period of time or against a baseline

% of food waste captured

Monitoring contamination

To monitor contamination of food waste collected over a period of time or against a baseline

% contamination (by weight) % containers contaminated

Monitoring residual waste collected

Measuring the amount of residual waste collected over a period of time or against a baseline

Tonnages kg per household per period

Monitoring participation

Measuring the participation rate over a period of time or against a baseline

% participation rate

Source: From WRAP, Improving the Performance of Waste Diversion Schemes – A Good Practice Guide to Monitoring and Evaluation, WRAP, Banbury, 2010.

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TABLE 8 Selective Indicators for Monitoring Food Waste Management Schemes in the Context of Food Policy. Main Target Category

Indicator

Food waste

Total annual volume of food losses and waste (tonne or kilogram) Annual number of events and campaigns aimed at decreasing food loss and waste Presence of policies or regulations that address food waste prevention, recovery, and redistribution Total annual volume of surplus food recovered and redistributed for direct human consumption

Source: From Milan Urban Food Policy Pact (MUFPP), Milan Urban Food Policy Pact, [Online]. Available: http://www. milanurbanfoodpolicypact.org/milan-urban-food-policy-pact-monitoring-framework/. [Accessed 22 2019 June].

TABLE 9 Selective Indicators for Monitoring Food Waste Management Schemes in the Context of Environmental Sustainability. Main Target Category

Indicator

Food loss and waste is reduced (or reused) throughout the food supply system

Decrease in total volume, economic value, and percentage of food loss and waste along the food chain Decrease in volumes of total on-farm food losses (e.g., due to lack of adequate storage and lack of labor) Decrease in annual volume of total urban food waste sent for disposal Decrease in annual volume and proportion of total food waste produced by households in the city region Increase in annual volume of total urban safe and nutritious food recovered and redistributed for direct human consumption Increase in annual volume of food waste recycled in feed, compost, energy recovery, etc. Presence of policy or strategy that appropriately addresses practical issues of (i) food loss and waste prevention, (ii) reduction, and (iii) recycling Increase in number of local/regional policies and programs that adhere to national food loss and waste programs and guidelines

Source: From J. Carey, M. Dubbeling, City Region Food System Toolkit Assessing and Planning Sustainable City Region Food Systems, FAO, RUAF Foundation, Wilfrid Laurier University, 2018.

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Despite the efforts of science institutes, research bodies, and governmental organizations to depict the current state and the progress made in food waste management, there are still concerns about the accuracy of data, the representativeness, and the uncertainties in what is being measured [166]. Suitable indicators allow a city, a region, or even a country to evaluate and judge its own performance concerning the effectiveness of food waste management services, while at the same time, they can provide valuable information for decisionmaking for service improvements [155].

3.4 Communication Plan and Raising Awareness Activities A successful food waste collection scheme is directly related to an effective communication plan for raising the public awareness concerning the scheme applied, which can only be achieved through informative and educational activities [167]. Furthermore, it is important for the various stakeholders involved to understand and support and ensure a well-functioning food waste collection Scheme [168]. Communication activities related to the implementation of food waste management schemes need not only to assist the consistent and effective exchange of information between key actors, local authorities, and citizens’ councils but also to enable the trust and ultimately the long-term engagement of people to sustainable management of food waste through transparent information [119]. The information provided can be instructive, thus aiming to inform people of how to manage their food waste and motivating [167]. Communication activities should be launched before the beginning of a source separation food waste program to create awareness concerning the importance of recycling and provide detailed information about the new service [94, 117]. Furthermore, these activities should be continued during the program to maintain and enhance the interest of the public. The key issues to be focused on an information program are • the protection of the environment, • the resource efficiency and energy saving, • the financial benefits of the success of the program, • the ethical point of view of the issue for future generations. There are various ways to raise public awareness concerning the food waste issue and to provide all the necessary information on how to deal with it [168]. Appropriate communication methods and activities need to be selected and applied to achieve high participation levels. Thoroughly understanding of the factors that influence the public recycling behavior—such as sociodemographic, psychological, and contextual factors—shall affect the success of a food waste collection system [91]. Some communication methods are more suitable for reaching people across a broad area (broad-brush methods), while others seem to be more beneficial when aiming at smaller areas (targeted

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methods) [169]. Communication methods can be categorized into several main groups such as follows [117, 170, 171]: Direct information activities—The direct information of the public presents the advantage of personal contact and immediate information of every household. This method includes the distribution of information leaflets and brochures, as shown in Fig. 22 [172], providing information about the source separation procedure and its benefits. Face-to-face contact through door-to-door campaigns seems to be particularly effective in rising participation rates in separate collection initiatives. Community engagement—The community engagement refers to raising awareness in various groups of audiences, such as schools, environmental associations and cultural associations, and public services and private enterprises. Engaging schools can be considered as a core action for engaging local groups and developing a recycling culture and consequently observing a change in behavior toward food waste management. Recycling initiatives, educational activities, and basic talks concerning food waste management and environmental protection are used to reach this special audience. Considering the members of local community groups and associations, they are generally willing to support any program related to environmental protection. In addition, it is also possible that these groups will provide valuable information to employees in the program, thus ensuring cooperation and support for the achievement of the objectives of

FIG. 22 Example of information brochure for direct information activities. Reproduced with permission from LIFE+ ISWM-TINOS, Deliverable 6-20(+) Information cards for students Development and implementation of a demonstration system on Integrated Solid Waste Management for Tinos in line with the Waste Framework Directive, 2014

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the program. In order for a food waste management scheme to be effective, all the stakeholders must be engaged including public services and private enterprises. Face-to-face information can be provided to employees, since awareness is a key factor for further implementation and deployment of the service. On line—Nowadays, raising awareness through Internet and digital communication platforms is essential as a complementary action to direct techniques of raising public awareness. This communication approach may include food waste–related information pages on the municipality’s website. Furthermore, public information screens in public waiting areas providing detailed information and promoting the scheme applied is considered very effective. Keeping in touch with the public and key target groups can be achieved through email and e-newsletters providing information about the status of the food waste collection program. Advertising—Advertising through radio, press, television, phone, and outdoor infrastructures can also assist in the distribution of information in different audiences. Newspaper and magazine publishers and reporters must be constantly informed about the reasons for the running, the operation, and the results of the program through press releases and interviews, while, additionally, brochures can be distributed as inserts in the newspapers. Television advertising can be implemented with special “spots,” through discussions with the project’s scientific staff and competent bodies of local authorities and through the screening of relevant films. However, the increased cost of such a communication activity is usually deterrent for most authorities. On the other hand, radio advertising seems to be more cost-effective including discussions about the food waste management program and the transmission of relevant slogans. Finally, outdoor advertisement, including posters (as shown in Fig. 23 [173–175]), billboards, and mobile advertisements on vehicles (busses, trains, and taxis), can contribute in raising awareness by getting simple and short messages across public. Additional information could be provided by telephone services where citizens can be informed regarding questions and problems arising during the operation of the program. Such problems relate to the filling of the bins, the long distance from the bins, and the cases where large quantities of target materials need to be disposed by individuals or industries. Certainly, public information programs through advertising are more costly than those of direct information. With direct information to the public, costs are limited to the production and distribution of printed material [117]. Increasing public awareness along with participation rate concerning food waste separate collection schemes can be also achieved by implementing economic or financial incentives. Economic incentives could be either positive or negative [176] and thus fall under the broad categories of rewards and charges [177], respectively. Different incentive schemes can be applied with pay as you throw (PAYT) (or direct and variable rate (DVR) schemes), charges for the disposal and treatment of residual waste and reward schemes that are the most commonly applied [176–178]. In brief:

FIG. 23 Example of advertisement posters for the valorization of food waste. Reproduced with permission from LIFE DRYWASTE, Dissemination project poster 2. Development and demonstration of an innovative household dryer for the treatment of organic waste, 2012; LIFE WASTE2BIO, Project dissemination material. LIFE11 ENV/ GR/000949. Development and demonstration of an innovative method of converting waste into bioethanol, European Commission, Waste2Bio, LIFE +, LIFE11 ENV/GR/ 000949, 2012-2016, 2016; LIFE ATHENS-BIOWASTE, Project dissemination material. Integrated management of bio-waste in Greece – The case study of Athens, European Commission, LIFE+, LIFE10 ENV/GR/000605, 2011-2014, 2012.

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Food Waste Generation and Collection Pay as you throw (PAYT) refers to billing for the collection services based on the weight or volume or frequency of collection or number of bags placed out for collection of household waste [179]. This type of systems seems to increase sorting of recyclables, encourage home composting, and reduce waste in bins, in addition with fair and transparent allocation of costs [177, 179]. Weaknesses of these systems are related to the encouragement of waste tourism and increase of illegal dumping [178, 179]. PAYT systems usually impose high variable tariffs for mixed, residual waste, no tariffs for food waste and lower tariffs for recyclable materials’ collection. PAYT are more efficient when combined with close-to-property schemes, for example, kerbside collection [119]. Charges for the disposal and treatment of residual waste refer mainly to landfill taxes and gate fees for the final disposal of waste. It seems that taxation related to landfill has a strong impact on the quantity of municipal solid waste landfilled for most of the European countries. This is proved by the fact that more municipal solid waste is sent for recycling and composting when increasing the cost of landfilling [178]. However, it needs to be mentioned that landfill taxes are not considered to be a direct incentive for citizens to reduce their waste, since they are not derived from the quantity of waste each household generates [119]. Rewards aim to encourage people to recycle more or dispose less waste and may be structured in different ways. Usually, vouchers can be given to citizens in respect to the recycling performance of their household or can be returned to the whole community due to the total contributions of the residents within that community. Indicative examples about rewards may be discounts in municipal services or rewarding products, for example, equipment for schools [177].

4 CONCLUSIONS AND PERSPECTIVES Food waste produced is getting increasing attention during the last decades as a global challenge to sustainability. Different parameters can significantly affect the quantitative and qualitative characteristics of food waste generated and thus the severity of the food waste problem. Such parameters can include climate conditions, demographics and other regional characteristics, living standards, consumption patterns and economic growth, level of industrialization, legislation, and political initiatives. One cannot fail to notice the distinct differentiation of food waste produced along the stages of the food supply chain in different regions in comparison with their economic status. The food loss and waste of medium/high-income countries (221 million tonnes) at the consumption stage appears to be more than triple compared with low-income countries (59 million tonnes). On the contrary, low-income countries show increased food loss and waste at the postharvest stage (188 million tonnes), two times higher than medium/high-income countries (105 million tonnes). It is then concluded that in medium/high-income

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countries, prevention measures need to be taken at consumption stage (behavioral change), while in low-income countries better management techniques need to be applied at postharvest stage. Insufficient handling of food waste can have dreadful environmental, social, and economic consequences. Physical, chemical, elemental, and bromological characteristics of food waste produced vary and show interesting fluctuations when different or even the same regions are examined over time. As a result, efficient handling of this constantly varying waste stream is a multivariate process as well. Designing and implementing a sustainable food waste collection scheme is a key factor for effective management of this special waste stream. Choosing the appropriate collection method along with suitable infrastructure, through a variety of technologies currently available, can contribute not only to optimal handling of food waste but also to achieving a sustainable and cost-effective management scheme. Separate instead of comingled collection is preferable and a proven good practice when it comes to food waste aiming at capturing a stream of increased purity, thus assisting in its effective downstream management. It should be mentioned that both food waste generation and collection are not static processes but change continuously over time based on a series of driving forces and factors. It is this multiparameter nature of the food waste problem that raises the need for using a continuously evolving monitoring and evaluation protocol through each of the stages of food waste production and collection and through the rest stages of the management scheme. Adequate monitoring allows the timely identification of problems occurring throughout the food supply chain, thus facilitating effective solutions. Additionally, one should not overlook the importance of keeping participants strongly engaged in the food waste management scheme applied by consistent educational awareness campaigns, with transparent procedures and frequent feedbacks from public to evaluate the satisfaction levels and optimize the performance of the scheme.

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[137] A. Balaskonis, S. Vakalis, A. Sotiropoulos, Comparison of 3 household food waste dryers in the context of food waste prevention and bioeconomy, Springer Nature Switzerland Appl. Sci. 1 (6) (2019) 648. [138] A. Ntolka, Examination of Physicochemical Parameters and Investigation of Valorization of Source Separated Biowaste (Thesis), School of Chemical Engineering, National Technical University of Athens, 2015. [139] S. Niakas, Food Waste Management in Municipality of Halandri, TAIEX-EIR PEER 2 PEER Workshop on Waste Management for Greek Cities, in Athens, Greece, 21 November 2019. [140] BioBag, Online, Available: https://biobag.ie/# (Accessed 22 June 2019). [141] Nature Bag, Online, Available: https://naturbag.com/bags/ (Accessed 22 June 2019). [142] Eco bags Designed for the Earth, Online, Available: https://ecobags.co.nz/why-choosecompostable-bin-liners/ (Accessed 22 June 2019). [143] Xybio, Online, Available: http://www.xinyuanpak.com/index.html, 2016 (Accessed 22 June 2019). [144] P. White, M. Dranke, P. Hindle, Waste collection, in: Integrated Solid Waste Management: A Lifecycle Inventory, Springer Science & Business Media, 2012, pp. 223–226. [145] J. Gonzalez-Estrella, C.M. Asato, J.J. Stone, P.C. Gilcrease, A review of anaerobic digestion of paper and paper board waste, Rev. Environ. Sci. Biotechnol. 16 (3) (2017) 569–590. [146] S. Uschnig, F. Amlinger, The Compost & Biogas Association—Austria (presentation), International Study Tour BIOWASTE, Austria, 2019 15–20 September, p. 6. [147] Sandwell Metropolitan Borough Council, Online, Available: http://www.sandwell.gov. uk/info/200160/bins_and_recycling/1971/food_waste (Accessed 22 June 2019). [148] N. Sankovic, Urban Biowaste - City of Ljubljana TAIEX-EIR PEER 2 PEER Workshop on Waste Management for Greek cities in Athens Greece, 21 November 2019. [149] D. Coss, P. Wells, I. Stone, Performance Analysis of Mixed Food and Garden Waste Collection Schemes, WRAP, Banbury, Oxon, 2010. [150] G. Folli, Food Waste Collection in Restaurants and Bars in the Touristic Area of Parma, TAIEX-EIR PEER 2 Workshop on Waste Management for Greek Cities, in Athens, Greece, 21 November 2019. [151] T. Mouratidou, Separate Collection of Bio-Waste in the Municipality of Vrilissia, TAIEX-EIR PEER 2 PEER Workshop on Waste Management for Greek Cities, in Athens, Greece, 21 November 2019. [152] Eunomia, Food Waste Collection: Update to WRAP Biowaste Cost Benefit Study, 2008. [153] ACR+, Municipal Waste in Europe - Towards a European Recycling Society, Victoires Editions, 2009. [154] C. Hanson, B. Lipinski, K. Robertson, D. Dias, I. Gavilan, P. Greverath, S. Ritter, J. Fonseca, R. van Otterdijk, T. Timmermans, J. Lomax, C. O’Connor, A. Dawe, R. Swannell, V. Berger, M. Reddy, D. Somogyi, Food Loss and Waste Accounting and Reporting Standard Version 1.0, Washington, DC, 2016. [155] D.C. Wilson, L. Rodic, M.J. Cowing, C.A. Velis, A.D. Whiteman, A. Scheinberg, R. Vilche, D. Masterson, J. Stretz, B. Oelz, ‘Wasteaware’ benchmark indicators for integrated sustainable waste management in cities, Waste Manag. 35 (2015) 329–342. [156] A. Scheinberg, D. Wilson, L. Rodic-Wiersma, Solid Waste Management in the World Cities, Earthscan, 2010. [157] R. Chifari, S. Lo Piano, S. Bukkens, M. Giampietro, A holistic framework for the integrated assessment of urban waste management systems, Ecol. Indic. 94 (2018) 24–36. [158] I. Oribe-Garcia, E. Borges, M. Vila, G. Nohales, M. Giavini, E. Amodeo, J. Dinis, G. Lyberatos, A. Alonso-Vicario, WESTE methodology for holistically evaluation of the waste management chain, in: Proceedings of 5th International Conference on Sustainable Solid Waste Management, Athens, 2017. [159] WRAP, Improving the Performance of Waste Diversion Schemes – A Good Practice Guide to Monitoring and Evaluation, WRAP, Banbury, 2010.

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Chapter | Four

Closing the Food Chain Loop Through Waste Prevention C. Chronia, Katia Lasaridia, K. Abeliotisa, and T. Maniosb School of Environment, Geography and Applied Economics, Harokopio University, Athens, Greecea School of Agricultural Science, Hellenic Mediterranean University, Crete, Greeceb

1 INTRODUCTION When, in the early 2010s, the Food and Agricultural Organization (FAO) of the United Nations (UN) provided the first cost estimates of the impact of food wastage, a disturbing fact was unveiled: calculated on a weight basis, roughly, one-third of all food produced for human consumption is lost or wasted, corresponding to yearly economic costs of approximately USD 1 trillion, social costs of USD 900 billion, and environmental costs of USD 700 billion [1]. On a calorific value basis, food wastage is around one-quarter of the total food produced. Although these figures are based on rough estimates of food wastage and consequently entail a degree of data uncertainty [2], they still reveal, in a most prominent manner, a high level of inefficiency with severe economic, social, and environmental impacts. In spite of the intense work carried out in the subject, there is still a lack of common terminology, which, together with the paucity of primary data, results in significant discrepancies in the reported values for food losses and waste in the literature, as well as in the classification of the various prevention, actions, and measures. For facilitating the discussion the definitions adopted in this chapter regarding food waste and losses are presented in Table 1. In economic, social, and environmental terms, every stakeholder along the food supply chain (FSC)—i.e., production, processing, transportation, wholesales, retails, and consumption—has a key, though differentiated, role [3, 10]. 107 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00004-X Copyright © 2021 Elsevier Inc. All rights reserved.

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TABLE 1 Glossary of Terms Used in This Chapter. Term

Definition

Source

Food losses

The decrease in edible food mass throughout the part of the supply chain that specifically leads to edible food for human consumption, i.e., from production up to, but excluding, the retail level, and does not reenter in any other productive utilization, such as feed or seed

[3–5]

Food waste

The decrease in edible food mass occurring at the end of the food chain, i.e., retail and consumption (including food and service providers)

[3–5]

Food wastage

Food losses plus food waste

[3]

Food surplus

Food and drink, produced beyond the nutritional need of humans, as well as food and drink that are or have been edible, but it will possibly be thrown away because it will not be needed or consumed

[6]

Inedible (unavoidable) food waste

Thrown away food commodities and drink that are not and have not been edible under normal circumstances (e.g., bones and banana peels)

[7, 8]

Avoidable food waste

Thrown away food commodities and drink that were, at some point prior to disposal, edible

[8, 9]

Potentially avoidable waste

Thrown away food commodities and drink that for some people are edible and others not or can be eaten depending on the preparation of the food (e.g., potato peels and bread crust)

[8, 10]

Geographic differentiation is also prominent (Fig. 1). In developing countries, food wastage is higher at the production and the immediate postharvest stages compared with the rest of the FSC, while in industrialized and developed economies, a large fraction of food wastage occurs at the consumption stage [5, 11]. In regard to economic impacts, food losses can nullify their associated monetary value and the monetary value of the resources consumed for their production, distribution, and consumption [12, 13]. Numbers are staggering. In the United States alone, USD 218 billion, corresponding to 1.3% of GDP, is spent every year for growing, processing, and transporting food that is never consumed [14], an unnecessary burden for businesses and households. In a different geographic and development context, in sub-Saharan Africa, the cost of postharvest grain losses alone for the period 2005–07 is estimated at approximately USD 4 billion per year or about 15% of the annual value of grain production, reducing real income and aggravating poverty [15]. With respect to the social impact of food wastage, each year about 1.3 billion tons or 1.46  1015 kcal/yr of edible food is wasted [16], while “821 million people go to bed on an empty stomach each night. Even more—one in three— suffers from some form of malnutrition” [17]. To better grasp the scale of the issue, it is estimated that if food losses and waste could be halved, 1 billion extra people could be fed [16]. A glimpse at the corresponding nutritional losses is equally alarming. Approximately 141 trillion calories per year or 1249 cal per

FIG. 1 Variation of food wastage by FSC stage and geographic region. Adapted from K. Flanagan, A. Clowes, B. Lipinski, L. Goodwin, R. Swannell, SDG Target 12.3 on Food Loss and Waste: 2019 Progress Report, 2011; Based on FAO, Global Food Losses and Food Waste. Extent, Causes and Prevention, FAO, Rome, 2011.

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capita per day were lost or wasted in the FSC of the United States alone in 2010 [18]. Another study in the United States indicated that in 2012 wasted food at the retail and consumption stages accounted for the loss of 1217 kcal, 146-g carbohydrates, 33-g protein, 57-g total fat, 5.9-g dietary fiber, 1.7-μg vitamin D, 286mg calcium, and 880-mg potassium per capita per day [19]. In the same first world country, in 2018, an estimated one in nine Americans was food insecure. That amounts to over 37 million people, of which more than 11 million were children [20]. Of course, this shocking situation of simultaneous high food wastage and prevalence of food insecurity to vulnerable social groups is not unique to the United States, but can be encountered in practically all developed countries. To depict the massive environmental impact of food loss and waste, FAO [1] reported that if food wastage, worldwide, could be deemed as a separate country, it would be ranked as the third largest greenhouse gas emitter, behind China and the United States. Environmental impacts of food waste are associated with natural resource depletion such as water pumping, energy and fertilizers used, land degradation and biodiversity loss, the embedded carbon throughout the life cycle of food items, and their management after they became waste [6, 16]. Once a food commodity is wasted or lost, all associated resources are also wasted, and the emissions created in the food supply upstream are in vein [21]. In an effort to quantify the global warming impact of the avoidable food waste in the United Kingdom [22], it is estimated that the corresponding carbon footprint ranges from 2000 to 3600 kg CO2-eq.t 1. This chapter attempts to present the policies, strategies, and best practices that are being proposed, piloted, or implemented worldwide to address the food wastage scandal. Its fundamental aim is to point out the need for the development of a holistic and cross-disciplinary approach, which involves the adoption of a new sustainable production and consumption paradigm and the integration of the circular economy concept throughout the FSC.

2 TOWARD A SUSTAINABLE AND CIRCULAR FOOD SUPPLY CHAIN As the increasing amounts of food loss and waste and their unfolding economic, social, and environmental consequences are being recognized, the need for an integrated framework for the management of the FSC is becoming widely acknowledged as a global priority, and significant resources are devoted to its development. This new framework should be grounded on overall sustainable use of resources, implementation of waste prevention strategies, efficient use of materials, and development of novel bioeconomy applications, for acquiring both material and energy resources from food waste [23]. Against this background an array of global targets, strategies, and initiatives has been developed, piloted, and, in some cases, widely implemented. Although of different nature, they share the aim to provide a basis for the improvement of the sustainability and circularity of the FSC. Indicatively, some of the most

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aspirational policy and legally binding targets are Target 12.3 of the UN Sustainable Development Goals (SDGs), the Circular Economy Package of the European Union (EU), and the promotion of the concept of the food waste (or food management) hierarchy.

2.1 Target 12.3 of UN Sustainable Development Goals In 2015 the United Nations General Assembly adopted a set of 17 integrated and indivisible Sustainable Development Goals, with 169 associated targets, as part of the 2030 Agenda for Sustainable Development. The SDGs came into force in January 2016, promoting the development of strategies to build economic growth and address social needs and environmental protection [24] and are set as following: (1) no poverty; (2) zero hunger; (3) good health and well-being; (4) quality education; (5) gender equality; (6) clean water and sanitation; (7) affordable and clean energy; (8) decent work and economic growth; (9) industry innovation and infrastructure; (10) reduced inequalities; (11) sustainable cities and communities; (12) responsible consumption and production; (13) climate action; (14) life below water; (15) life on land; (16) peace, justice, and strong institutions; and (17) partnerships for the goals. In regard to the mitigation of the food wastage challenge, special attention should be paid to the 12th SDG, which pursues “to ensure sustainable consumption and production patterns” [24], through 11 distinct targets. The third target under SDG 12 (Target 12.3) postulates “halving per capita global food waste at the retail and consumer levels and reducing food losses along production and supply chains (including postharvest losses) by 2030” [24]. A successful sustainable production and consumption pattern in the FSC would prerequisite proper use of resources and mitigation of environmental degradation. Special attention should be also paid on the operation of the supply chain in a way that everyone, from producer to final consumer, would be involved. This could include actions for the improvement of consumers’ literacy on sustainable consumption and lifestyles, provision of adequate and comprehensive information through standards and labels, and engagement of the consumers in sustainable public procurement.

2.2 The European Union Circular Economy Package The first decisive step to tackle food waste is to recognize it as an issue of great significance and concern. In 2011 the European Commission (EC) identified food waste as one of the key sectors to address resource efficiency [25] and—as foreseen in the Waste Framework Directive 2008/98/EC—invited all member states to combat food waste through their National Waste Prevention Programs [7]. Since then, EC has progressively developed and broadened a coherent policy and legislative framework to fight against food wastage and to substantially improve food waste management. In 2015 the EC launched the Circular Economy Package (CEP) and its action plan, through which the EU and member states are committed to

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contribute to meeting the target 12.3 of the 2030 UN Sustainable Development Goals, “to halve per capita food waste at the retail and consumer level, and reduce food losses along production and supply chains” [26]. The CEP resulted into legislative documents amending a series of EU directives, including the Waste Framework Directive (2008/98/EC), which was amended by Directive (EU) 851/2018. In this document, member states are required to “take measures to promote prevention and reduction of food waste in line with the 2030 Agenda for Sustainable Development.” More specifically, they “should aim to achieve an indicative Union-wide food waste reduction target of 30% by 2025 and 50% by 2030,” and they should measure progress toward this aim using a common measurement methodology, according to the Commission Decision C (2019) 3211 (final and Annexes). Specific food waste prevention awareness programs should be developed and food donation facilitated, including the use of financial instruments. It is worth noting that EU member states are encouraged to contribute to the attainment of UN SDG 12.3, but this is not a legally binding requirement. Nevertheless, they are required to develop food waste prevention programs and establish baseline and regular measurements for food waste, as well as yearly reporting, across all sectors of the postharvest FSC. The EU will consider the feasibility of establishing a binding food waste reduction target to be met by 2030, after examining the country food waste data submitted by the end of year 2023. The principles of circular economy give precedence to attitudes and processes that close material loops, cascade used resources, discover new secondary resources within waste, and drastically prevent waste generation [27]. Under the lens of circular economy and industrial symbiosis, food waste is a mighty resource of useful products [28]. Food waste could be utilized as raw material for the production of new secondary products, supporting the goal of “zero waste” economy [29]. By-products of fruit and vegetable processing may contain high concentrations of phenolic compounds, antioxidants, and fibers, while waste derived from meat processing may contain recoverable amounts of proteins, collagen, and gelatin. The valorization of food waste components could provide new channels for the production of pharmaceuticals, chemicals, fuels, etc. [28].

2.3 The Food Waste Hierarchy In the quest for sustainability, waste management worldwide is moved toward waste minimization practices through the concept of the waste hierarchy. In the EU the waste hierarchy is introduced into its legal system through the Waste Framework Directive [30]. The hierarchy prioritizes waste prevention as the most favorable option, followed by preparation for reuse, recycling, energy recovery, and finally disposal (which includes both landfill and incineration with low energy recovery) as the least favorable option. However, in the case of food waste, studies have shown that some further specifications should be

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added to this hierarchy to better define what consists prevention, preparation for reuse, and recycling for food waste and where our priorities should lay [6]. At this point the distinction between the terms “food surplus” and “food waste” is necessary to better define the scope for prevention actions and the preferable management options across the whole FSC. Food surplus is defined as food and drink commodities produced beyond the nutritional needs of humans. Food waste is the result of food surplus when the latter becomes inedible [6]. It is generally argued that, at a global scale, a level of food surplus is required to safeguard food security in case of unpredictable conditions affecting agricultural production [31]. However, according to the FAO food balance sheets, in developed countries, the amount of food surplus is by far greater than the estimated security quantities, rising to well over 3200 kcal/ca/day [4]. Moreover, food surplus is not solely produced on purpose, as a measure to guarantee food security. Especially at the consumption level (i.e., households and food service sector), it is usually generated unintentionally, due to overproduction, overestimation of food needs, overordered, food mismanagement (e.g., unproper storage and handling and food label illiteracy), obsolete seasonal stock, cultural issues about food consumption, and dietary habits or even lifestyle patterns [13, 32–34]. Food surplus is considered as a major source of food waste, unless it is redirected to other users for human consumption (i.e., other stages of the supply chain or other consumers). Thus an overall management framework for food surplus and food waste can be described, along with the positioning of the various management options in the adapted food waste hierarchy (Fig. 2). Changes in the food supply chain and the consumption patterns, leading to prevention of excess surplus and avoidable food waste, are the first priority, wherever possible. This is followed by redistribution of food surplus for human consumption, mainly to vulnerable social groups to help combat food insecurity. Recycling comes next for any surplus that is not directly consumed by humans, as well as the unavoidable food waste fraction. It takes the form of various types of material recovery. These are prioritized on the basis of legal requirements that may vary among countries, life cycle assessment, and economic feasibility. Conversion to animal feed, composting, and novel approaches, such as production of bioplastics and other chemicals or extraction/production of high-value compounds, all fall in this category. Further industrial processing, to produce other foods or drinks (such as the Toast Ale beer, brewed with surplus fresh bread in the United Kingdom), should also be considered as recycling. Ideally, such activities should not compete with redistribution for human consumption for food that is fit to be consumed, if there is a demand for it. Energy recovery, not only mainly in the form of biogas production from anaerobic digestion but also including emerging technologies like biohydrogen and bioethanol production, is the next management preference. According to the hierarchy, composting and anaerobic digestion with land use of the digestate are preferred to anaerobic digestion with plain energy recovery or other forms of energy

Management options

Prevention

Most favorable

Food surplus Fit for human consumption

Redistribution for human consumption

Prevention

Unfit for human consumption

Prevention Avoidable and possibly avoidable

Redistribution for human consumption

Animal feed

Recycling (animal feed, composting)

Composting

Food waste

Energy recovery (e.g., ) anaerobic digestion

Animal feed Unavoidable

Disposal

Composting Anaerobic digestion Disposal

Least favorable

FIG. 2 The management framework for food surplus and waste and the food waste hierarchy. Adapted from E. Papargyropoulou, R. Lozano, J.K. Steinberger, N. Wright, Z. bin Ujang, The food waste hierarchy as a framework for the management of food surplus and food waste, J. Clean. Prod. 76 (2014) 106–115.

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recovery; however, in practice, this will highly vary depending on the local circumstances. As in the classic waste hierarchy, the least favorable option is disposal. In this chapter the first two steps in the food waste hierarchy and the preparation of feed from food are discussed.

3 PREVENTION OF FOOD SURPLUS AND AVOIDABLE FOOD WASTE Prevention of food surplus and waste is strongly connected to the achievement of the Sustainable Development Goals. It contributes to the improvement of food security, waste management, and the sustainable exploitation of resources [35, 36]. Although all actors of the different stages of the FSC are responsible for food wastage, their share responsibility exhibits a wide geographic variation (Fig. 1) depending on the regional economic and social framework [3, 5, 10, 11, 37]. Unsurprisingly, wastage generated at consumption level is much more significant in middle- and high-income regions and much lower in low-income regions [3]. In Europe and North America, consumption accounts, respectively, for about 42% and 58% of the total food wastage, while it is responsible for only 5% and 11% in sub-Saharan Africa and South and Southeast Asia. In contrast, in the latter two regions, food losses at the production and handling/storage stages account for 72% and 65% of the total wastage, respectively. The sources of food wastage and the required prevention measures vary accordingly. In less developed countries, investments in simple traditional and novel technologies to combat losses at the farm, storage, and distribution have a great potential to reduce losses and combat poverty [3, 11]. Some of these interventions constitute straightforward agriculture modernization, such as better pest control and irrigation to reduce losses in the production and better conditions and wider use of refrigeration in storage and transport. Although simple in concept, these measures require significant investment that, typically, is well beyond the means of the local farmers and retailers and often beyond the means of the respective countries. The international development aid to agriculture in less developed countries may play a significant role in addressing this type of food wastage [3, 38]. In developed countries the main causes of food wastage are rooted in the decision-making mechanisms and the behavior of suppliers, retailers, and consumers, making efficient prevention a more complex issue [5, 23, 37, 39]. On that ground, “hot spots” of food waste generation and prevention options in every single stage of the FSC should be identified, described, and explicitly analyzed, taking into consideration the socioeconomic background. According to some scholars the main causes of food waste lay with the problem of structural overproduction and overconsumption [40]. Large food surpluses are produced in all stages of the FSC, which are pushed down to consumption through elaborate marketing practices, leading to overconsumption

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and, inevitably, food waste. Thus current economic models and practices are in fundamental clash with the stated priority for food waste prevention. This is why most measures adopted focus on the lower steps of the food waste hierarchy when food surplus has already been produced [40]. This is a serious argument, and the question whether effective food waste prevention over the whole FSC can be achieved under the current economic models should be retained, although it is out of the scope of this chapter’s discussion. Nevertheless, an increasing number of countries, companies, and actors in the civil society are committing to combat food wastage, in line with the SDG 12.3, and a large variety of tools and campaigns for food waste prevention have been developed for the different stages of the FSC, with varying level of success [11, 41–43]. Goossens et al. [42] provide an excellent overview of over 200 food wastage reduction measures identified in the literature, either implemented—at very different scales—or proposed as promising, which are further grouped into 75 groups. The measures cover both prevention and redistribution for human consumption, span across all sectors of the FSC, and range from IT tools and technological solutions to education and awareness raising for professionals, especially in the food services, and consumers and from voluntary agreements to legislation interventions. Many measures concern imperfect fruits and vegetables, an issue that has been widely discussed and addressed at various scales, and for this reason, it is further analyzed in Section 3.1. Traditional and more innovative interventions for primary production, storage, processing, and packaging include good agricultural practices to avoid damage, pests, or contamination; early warning systems for potential hazards to agriculture; improved postharvest technologies and storage; lower temperature in the cold chain and proper cold chain management; manufacturing line optimization; and packaging adjustments, such as smaller sizes and storage and freezing instructions on packaging and functional and smart packaging to increase the useful life of fresh produce (e.g., breathable polymer films, modified atmosphere packaging, and ethylene absorbing strips to increase self-life of packaged fresh produce) [42]. The retail (and wholesales) sector have a small share of the total food loss and waste, typically estimated to below 10% [44]. However, due to their crucial position in the FSC and their strong purchasing and marketing power, often concentrated in a very small number of companies, they can exert a high influence in all FSC stages, from production and processing to consumption. Therefore their role in food wastage prevention is crucial. Measures include the facilitation of the adoption of packaging managerial and technological innovations, providing market outlets for imperfect but totally safe produce; improved storage and refrigeration conditions to extend products self-life; good inventory management (e.g., shorten the period between buying and selling, use of “first in-first out” storage, and daily control of fresh produce); improved forecasting using demand forecast models and advanced IT tools, such as machine learning; promote products nearing their best before date, and facilitate overall change and correct interpretation of date labeling; reduce product line abundance,

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especially of fresh produce at the end of the day; staff training, as well as information and awareness campaigns for consumers; and development of strong food redistribution and donation networks [42]. The food service sector, including hospitality, which is of particular significance in tourist regions, has also a significant role in combating food wastage. It has been shown that creating awareness among kitchen and food and beverages management staff about the amount of food wasted may lead to significant savings [45]. A number of IT tools have been developed to this end, such as Leanpath, Winnow, and ResourceManager-FOOD [43, 46, 47], with very positive results after their implementation. Good practices for inventory/stock management and storage (e.g., “first in–first out,” flexible menus, ensure cold chain is sustained, and prevent spoilage); forecasting demand (often through specialty IT tools); careful portioning and smaller serving trays and plates; and nudges and prompts, especially in buffets (such as “Only take what you will eat” or “Welcome back! Again! And again! Visit our buffet many times. That’s better than taking a lot once”) have all been shown to be effective tools for food wastage prevention [42]. Mobile apps to promote restaurant food that has not been sold till late to potential customers at reduced price have also been developed and successfully used in several countries (e.g., Karma, YWaste-reduce food waste, Too Good To Go, and OLIO). The food service sector is also significant to food redistribution programs, although several liability barriers need to be overcome (also see Chapter 15 on food waste policy). Private households have a large share of food waste production in developed countries (Fig. 1). As a result a lot of research has focused on household behavior and the causes for food waste generation, indicating that this is deeply rooted in food provisioning and preparation habits and routines, which require a concerted action to change [10, 43, 48]. To this end a large number of wide awareness raising campaigns, seeking to inform, sparkle self-reflection, and change social norms, and practical information tools on how to plan food provisioning, store, refrigerate and freeze food, and cook using leftovers have been developed in several countries. An extensive review of many of these campaigns and tools is provided in the results of the EU REFRESH project [43] and Goossens et al. [42]. Here a special mention will be made to three of them, characterized by their length in time and impact, which is multiplied by the fact that they have been developed in English. This, of course, does not undermine the importance and effectiveness of many other successful food waste awareness campaigns in different countries. The WRAPa (UK) campaign on “Love Food Hate Waste” (https://www. lovefoodhatewaste.com) is one of the first of its kind; it was backed by a wide body of pioneering research in food waste prevention, including measurements a

WRAP (Waste and Resources Action Programme) is a registered UK charity, which was established in 2000 and receives funding from the Department for Environment, Food and Rural Affairs (DEFRA), the Northern Ireland Executive, Zero Waste Scotland, the Welsh Government and the European Union.

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of the quantities wasted, and continues for over 10 years, evolving to address different aspects of consumer behavior leading to food waste generation and prevention and provide new messages to keep the public interest. It includes a website with a wealth of information, including tools for recipes, correct food storage, and good refrigerator use and maintenance, as well as tools for tracking one’s food waste. At the other side of the Atlantic, the Save the Food campaign (https:// savethefood.com) of the not-for-profit organization National Resources Defense Council (NRDC), founded in 1970, provides a comprehensive website with tools and detailed information on meal and shopping planning, recipes, and storage instructions. At the global scale the most pronounced campaign is the United Nations Environment Programme (UNEP) Think.Eat.Save (https:// www.unenvironment.org/thinkeatsave/), of the Save Food Initiative, in partnership with FAO, contributing to the Sustainable Food Systems Programme of the 10-Year Framework of Programmes on Sustainable Consumption and Production (10YFP). The Think.Eat.Save website is developed as a portal to showcase innovative ideas and provide news, information, and resources. It has general information on food waste, infographics on the environmental footprint of various foods, tips to reduce food waste, links to mobile apps, and toolkits for businesses, governments, and consumers. Measures to facilitate and enhance redistribution of food surplus to vulnerable social groups span across the whole FSC and are described in detail in Section 4 of this chapter.

3.1 Creating Markets for Imperfect Fruits and Vegetables Over the last decade, attention has been drawn on a major, yet for long time ignored, source of avoidable food losses: the esthetic standards that fresh produce should comply with to reach the market. These aesthetic standards reflect the reluctance of retailers and consumers to market and consume, respectively, “ugly” or “wonky” fruits and vegetables, that is, food commodities that deviate from the optimal consumer-perceived aesthetic standards of color, shape, size, and weight, [49–51]. These standards have been imposed by different market-defining actors, such as retailers, consumers, and trade regulators [13, 49, 52, 53], and are a potential cause of food wastage. However, up to date, empirical research, data, or estimates on the impact of aesthetic specifications on food waste are very limited. Quantification is inherently difficult, as suboptimal products are hardly recorded in production statistics. Some of these products may still be sold in open markets or to the food processing industry (e.g., for juice or jams), used as animal feed or be moved further down the food waste management hierarchy, to be composted, anaerobically digested, or just discarded. To address this knowledge gap [50], using semistructured interviews in Germany and the Netherlands estimated that aesthetic standards result in a wastage of around 20% on average of the total produce. However, there was a

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considerable variation in the results (ranging from 2% to 40%) depending on the product and the type of cultivation (greenhouse vs open farm). Porter et al. [52] used production statistics and loss factors from the literature for different crops to provide estimates for the food wastage due to aesthetic reasons in the United Kingdom and the European Economic Area (EEA). They estimated that on-farm aesthetic standard losses relative to total farm production in the EEA and the United Kingdom is 4%–37% and 6%–39%, respectively, with a “central” value of 14% for the EEA and 20% for the United Kingdom. This accounts to a wastage of up to 4500 kt and 51,500 kt of edible crops per year in the United Kingdom and the EEA, respectively. As the environmental, social, and ethical dimensions of this loss were highlighted in the last decade, a series of information and awareness raising campaigns, as well as demonstration projects, have been developed by public and private initiatives. The list includes the campaign “Love Food Hate Waste” of the Waste Resource Action Programme (WRAP) in the United Kingdom (https://lovefoodhatewaste.com); the awareness campaign of WWF Greece on imperfect nutritious fruits and vegetables, with the title “There is nothing as ugly as food waste” (Fig. 3) (https://www.wwf.gr/campaigns/ugly-food); and the FLAW4LIFE project “Spreading Ugly Fruit Against Food Waste” in Portugal, cofunded by the EU LIFE Programme (www.flaw4life.com). In Catalonia, Spain, the social enterprise project “Espigoladors” aims at the rescue of “ugly” or excess produce, which they redistribute or use for the production of other food products, such as jams and sauces (http://www.espigoladors.cat).

FIG. 3 Poster from the information campaign “There is nothing as ugly as food waste” of WWF Greece.

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In addition, during the last 5 years, a market for “wonky” fruits and vegetables has begun to formulate. In the United States, at least two companies, that is, “Imperfect Produce” (https://www.imperfectproduce.com) and “Hungry Harvest” (https://www.hungryharvest.net/), rescue and provide fresh produce, which is nutritional but beneath the typical aesthetic standards of the market.

4 REDISTRIBUTION OF FOOD SURPLUS FOR HUMAN CONSUMPTION Redistribution of food surplus that would have otherwise been wasted could contribute to both the alleviation of food insecurity and the mitigation of food waste environmental impacts, achieving significant gains in environmental, economic, social, and ethical terms [34, 54]. According to FareShare, a UK charity targeting to the relief of food poverty and food waste reduction, the recovery and redistribution of food surplus to people in need are efficient ways to turn an environmental problem into a social solution [55]. Food surplus that can be donated is produced throughout the entire FSC. Indicatively, in 2013, 22% of the food donated to the 256 Food Banks in Europe was derived from the food industry, 17% from the retailing sector, and 14% from individuals [56]. The redistribution of food surplus can be accomplished through an array of different mechanisms, which link and sometimes bond the producers and the potential users of the food surplus in a safe and (preferably) discreet manner. These mechanisms may not only include the redistribution of food surplus from retailers or the catering sector to people in need but also embrace the initiatives of gleaners, foragers, and freegans “that seek to disrupt notions of food as a commercial commodity” [57]. Redistribution of food surplus for human consumption may also include the support of industrial synergies for the development of new products from food surplus, for example, desserts with yoghurts and fruits, juices, and chutneys [13]. The potential of the consumption stage of the food supply (i.e., restaurants, catering, and on-the-go cafes) to contribute to the redistribution of food surplus is significant but has not yet been fully taped and optimized. A main barrier is that restaurant managers are reluctant to proceed to food donation in view of (i) liability concerns, as food safety issues may lead to legal prosecution, and (ii) logistics, given that advanced transportation and storage infrastructure are needed to ensure that donated food arrives to its recipients at the same good condition as it leaves the restaurant [45]. Gleaning, i.e., collecting leftover crops from farmers’ fields after they have been commercially harvested, is another way to recover food surplus that can be considered as some form of food redistribution. However, only scarce and fragmented information on initiatives regarding gleaning is available in the literature and technical reports [54, 58]. Still, results strongly suggest that gleaning has the potential to provide noteworthy benefits [59, 60] and showed that 65% of the unharvested crop in 13 fields of a 121-ha North Carolina vegetable farm

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“was of wholesome, edible quality, although the appearance may not meet buyers’ specifications for certain markets.” In the Heartside Gleaning Initiative in Grand Rapids, Michigan, 7711 kg of fresh produce were collected and provided to low-income individuals and food pantries from June to October 2014 [58].

4.1 The Current Situation Through Good Practices and Initiatives Initiatives, programs, and practices to promote and/or boost redistribution of food surplus for human consumption are implemented in a number of countries. Many of them demonstrate remarkable results in terms of both the provision of hunger-relief services and the mitigation of food waste generation. Ideally, results of all these endeavors would build an evidence based on the development of policies and strategies on country or region level, all over the world. In reality, though, the services and their organization vary a lot among and within countries, making it difficult to create an integrated strategy [13, 61]. Food redistribution players remain largely fragmented and independent from each other, while they deal with logistic issues that threaten their long-term sustainability [13]. Their cross-sector cooperation with all donation stakeholders (i.e., wholesalers, retailers, consumption sector, and regulatory bodies), under the support of a united, larger redistribution system and of national commitment, is a prerequisite for the optimization of the donation channel [13, 61, 62].

4.1.1 FOOD BANKS The concept of the Food Banks sprang from John van Hengel, a retired businessman and volunteer at the soup kitchen in Arizona, USA, in 1967 [34]. Since their establishment, they have played a key role in the recovery and redistribution of food surpluses. In 2018 in the United States, Feeding America, the nation’s largest network of approximately 200 food banks, redistributed 4.3 billion meals to people facing hunger, of which only a small portion was food purchased (by donors or through programs) to fill donation gaps. These meals were provided by grocery and retail companies (1.4 billion meals); the manufacturing sector (718 million meals); fresh produce (687 million); federal commodities (619 million meals); purchased food from manufacturers to fill donation gaps (540 million meals); snap meals (229 million meals); and emerging retail donations from restaurants, hotels, and convenience stores (63 million meals) [63]. In the same year, in Europe, the network of European Food Banks Federation (FEBA), which consists of 421 Food Banks and branches, redistributed 781,000 tons of food— equivalent to 4.3 million daily meals (a total of 1.57 billion meals)—to 9.3 million people in need through 45,700 charities [64]. At this point, it is worth mentioning that although the first food bank in Europe was launched as early as 1984, food bank networks proliferated as a response to the economic crisis of 2008 [32]. Indicatively, from 2010 to 2012, the number of food banks in the United Kingdom increased by 372% [65, 66].

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Although food banks all over the world share the same concept, their operation models vary, depending on whether they (i) provide food directly to people in need or to intermediaries, such as soup kitchens, food pantries, and community groups; (ii) are run by charities, churches, community groups, or even individuals; and (iii) rely on public or private funding or in-kind donations [32, 61, 66–71]. There are two main lines of criticism regarding food banks. The first one questions their efficiency to cover consistently and fully the nutritional needs of the recipients, as often the food available in food banks may not meet the nutritional standards required to offer a healthy meal. At present, there are efforts to address this barrier via monetary donations that can cover the cost for additional food to ensure a balanced diet, but there is still a lot of space for improvement [66, 67, 71]. The second is political; it questions the fundamental conditions that lead to poverty and food insecurity in developed countries and the choice of governments to shift responsibility to food banks and charity, rather than providing a robust social welfare [65, 66].

4.1.2 PUBLIC AND PRIVATE FUNDED INITIATIVES Charities and nonprofit organizations play a key role in the salvage and redistribution of food surplus to deprived people. Their contribution to relieving hunger and poverty, as well as tackling food waste, is indicatively illustrated herein through the action of FareShare in the United Kingdom (UK) and Boroume in Greece. FareShare (fareshare.org.uk) is the largest charity in the United Kingdom, aiming at fighting hunger and food waste, through the redistribution of surplus food from the FSC to charities and community groups that turn it into meals. In 2018 FareShare managed 16,992 tonnes of edible food and redistributed it to 9653 charities and community groups, such as homeless hostels, children breakfast clubs, elderly’s lunch clubs, community cafes, and domestic violence refuges, across the United Kingdom. FareShare is a member of both the European Food Banks Federation (www.eurofoodbank.org) and the Global Foodbanking Network (www.foodbanking.org). In Greece the nonprofit organization Boroume (meaning “We Can” in English—www.boroume.gr) was founded in January 2011 to combat malnutrition in Greece and, in parallel, to reduce food waste through the redistribution of food surplus to charities. On a daily basis, Boroume links food donors and recipient organizations (e.g., welfare institutions, soup kitchens, and municipal social services) via the means of a call center, which matches the food donations to the organization in need. In 2018 8.5 million meal portions of food were salvaged and donated to welfare actors, corresponding to more than 23,291 meal portions per day, of an estimated value of €12.8 million [72]. Furthermore a series of EU-funded projects are implemented with the aim to demonstrate, promote, and establish the redistribution of food surplus for human consumption, on local, national, or international level. Such is the A2UFood project [46], cofunded by the European Regional Development Fund, through

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the Urban Innovative Actions Initiative. The project aims to redistribute surplus food of high quality to people in need, through the development and operation of a “second opportunity restaurant,” while it also undertakes activities for addressing different aspects of food waste prevention and recovery, such as computeraided awareness raising for families and hotels.

4.2 Bottlenecks for Food Donation Although the redistribution of food surplus through donation is deemed by many as a promising and sustainable solution for both hunger relief and waste prevention, it is often impeded by safety, operational (mainly logistics), and social issues (Table 2).

TABLE 2 A Nonexhaustive Overview of the Barriers of Food Donation. Donation Type of Factor Barrier Donor

Liability issues

Description

Solutiona

Retailers and kitchen managers are discouraged to donate food surplus, to avoid lawsuits associated to food safety

Food donation was regulated [45] by the US congress in the Bill Emerson Good Samaritan Act

Reference

Operational Insufficient refrigeration and/or onsite storage

–

[45]

Acceptor

Social

Users of food bank had concerns about the social stigma of food aid

–

[73]

Donor/ acceptor

Regulation

Confusion in EU as to – whether food that has passed its “best before” date is safe or of inferior quality

[32]

Process

Operational The quantity or type of food is not known in advance

Development and application of forecasting models

[74]

Quantity of donated food and frequency of donations vary over time

Development of empirically based strategies (numerical study and predictive models)

[69]

Fragmented redistribution efforts and difficulties in transport and availability of the processing facilities and storage space

Development of policies and [13] information-based instruments to coordinate all FSC stakeholders’ actions and make it feasible to maintain progress in saving food and reducing waste

a

Solutions that have been suggested or presented as good practices within the respective reference.

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4.2.1 REGULATION ISSUES As often food is donated when it is close to the end of its shelf life, concerns have been voiced by donors, acceptors, and regulators over the safety of the offered items. In the literature, many scholars have investigated whether the donated food is wholesome or of adequate sanitary or nutritional quality [61, 75, 76]. In the EU, typically the concerns of food donors and acceptors stem from regulations or their misconstruction. All organizations that place food on the market, including the nonprofit ones, have to comply with the relevant, stringent EU food health and safety legislation. The report of Bio by Deloitte [32] highlights that the EC Regulation 178/2002 “underlines that all factors taking part in food donation have to comply with the EU food legislation concerning responsibility, liability traceability, and food health and safety.” More specifically, they have to comply with the General Food Law (EU Regulation 178/2002), the Food Hygiene Package (EU Regulations 852/2004, 853/2004, and 854/2004 and Directive 2004/41/EC), the EU Regulation 1169/2011 on the provision of food information to consumers, the Council Directive 2006/112/EC, and the EU Regulation 223/2014 regarding the Fund for European Aid to the Most Deprived. As a result, potential donors, especially kitchen managers in the hospitality sector, are deterred from donating the food surplus to obviate hygiene risks that could lead to liability [32, 45]. To tackle this barrier an agreement is usually signed between food donors and food banks/charities/nonprofit organizations, stating that the responsibility after the gate of the donor is transferred to those who accept the donated food [61]. Another good practice is provided by Italy, which has set the Good Samaritan law, identifying food banks as the final acceptor/consumer, and consequently, food donors are liable for food safety to the food banks alone, not to the final individual acceptors of donated food commodities [32]. The aforementioned law was based on the Bill Emerson Good Samaritan Act (House of Representatives Report 104-661), which was signed into law in 1996 in the United States. The Bill Emerson Good Samaritan Act was developed in an effort to encourage food and grocery donation to nonprofit organizations by protecting donors from liability issues. In parallel, in the EU, ignorance, confusion, and misunderstanding of food date marking hinder food business operators to offer food surplus and people in need to accept the offer. EC Regulation 1169/2011 defines date markings and clearly states that products that have passed their “best before” date can be still consumed, provided that they have been properly stored. However, less than half of the European citizens (47%, with a significant country-level divergence) can understand the meaning of “best before” dates [77]. A recent study commissioned by the European Commission reveals that national practices and the legal framework in some EU member states may discourage or forbid donation of food that has passed its “best before” date, although it is allowed under EU rules [78].

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4.2.2 OPERATIONAL ISSUES Two key barriers of food donation mechanisms lie on their inherent operational characteristics. The first is associated with the fact that no one can predict where, when, and how much food surplus will be donated. The second is that most of the recovery and redistribution players are small and act independently. Food recovery and redistribution through donation is a dynamic process, strongly dependent on available quantities, time, and place [74]. The operational donation scene is fragmented, consisting of many food rescue and redistribution organizations, varying in terms of structure, personnel, facilities, and infrastructure. Most of them have, almost on a daily basis, to adapt their logistics and operations according to a varying landscape of donors’ offers (e.g., unpredictable quantities and last minute cancelation). Depending on the quantity and type of donated food they receive, each day they have to (re)design the routes, link the donated items with the most suitable acceptor, and/or find a proper storage space. The uncertainties in the food supply (donation) and the consequent daily operational adaptations may lead to increased operating costs, insuperable logistics challenges, wastage of salvaged food, and unfair distribution of food items [74]. Such challenges may pose a serious threat to the long-run existence of small organizations [13]. To facilitate the logistics of food salvage and redistribution, a series of prediction models have been employed [69, 74, 79]. Nair et al. [74] suggested that structural equation models (i.e., models that combine the relative contribution of a multitude of factors) can efficiently forecast the average daily donation amount per category and food provider and therefore can be utilized for policy needs. Sengul Orgut et al. [79] tried to approach the issue of equitable and effective distribution of food donations via food banks under capacity uncertainty through the utilization of two robust optimization models. Targeting at the improvement of the overall operation of food rescue and redistribution organizations in the United Kingdom, Facchini et al. [13] suggested that “the development of a larger redistribution system needs to be supported and sustained through a stronger national commitment, as well as a stronger communication and collaboration between all stakeholders involved.”

5 RECYCLING FOOD WASTE TO ANIMAL AND FISH FEED The allocation of resources (i.e., land, energy, water, and minerals) between the production of food for humans and animal feed is a longtime thorny issue. On the one side, it is argued that animal source foods contribute to the improvement of human diet and food security, and therefore their production should have a fair share of all available resources. Livestock contributes to the exploitation of marginal lands, provision of valuable nutrients to humans (e.g., 17% of kcal consumption and 33% of protein consumption throughout the globe) [80], higher crop productivity through the production of manures, improved agricultural productivity through draft power and transport services, and, last but not

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least, increased earnings at individual or society level [81, 82]. On the other side, opponents highlight that the production of animal source foods requires more energy and material resources in comparison with the production of an equal amount of plant-based calories; this eventually undermines both the environment and food security [83, 84]. Animal breeding accounts for about 7.1 Gt CO2 -eq. per year or 14.5% of all human-induced greenhouse gas emissions [85], while it is considered as one of the main reasons for the conversion of forests and native grasslands into agricultural land, leading to biodiversity loss [86]. Nowadays, it is estimated that approximately 70% of the total arable land and grassland is used by the animal breeding sector [86]. Every year, approximately 6 billion tons of animal feed (dry matter), including one-third of the global cereal production, is used [81]. As the demand for animal source foods is growing [87], the aforementioned figures are anticipated to rapidly rise and, consequently, exacerbate the debate for food and feed production shares. On that account the investigation of a more sustainable approach for the production of animal source foods has emerged as crucial and has been incorporated in the Sustainable Development Goals [24, 88]. Decoupling animal feed production from the use of arable land, through the production and utilization of low-impact alternative feed, may constitute the basis for an effective solution. Hence, many groundbreaking options, such as the use of insects, bacteria, or algae as animal feed, have been investigated [89]. During the past 10 years, a retrofit vision and practice, the conversion of food surplus and waste to animal and/or fish feed or dietary supplement, without compromising public and animal health, has been suggested by a number of researchers and decision-makers [84, 90–92]. Their view is based on three distinct pillars: (i) the volatility in the price of conventional feed [93]; (ii) the pressing environmental and health impacts of conventional feed [93]; and (iii) the comparative advantage of converting food waste into animal feed, in terms of environmental impacts, over the rest food waste treatment options, i.e., anaerobic treatment, composting, incineration, and landfill disposal [90]. The upcycling of food waste to animal and/or fish feed can be accomplished either directly, through the chemical/physical processing (mainly heat drying) of food waste [94], or indirectly, through insect (e.g., black soldier fly larvae) bioconversion [95, 96]. The selection of the preferred method will depend on the food waste source and composition, available technologies, and regulatory framework, while the product (feed) may vary in terms of composition, nutrients, and use.

5.1 The Current Regulatory Framework Up to the end of the 20th century, the utilization of food waste as animal feed— particularly for domestic animals, such as poultry in farms and pigs in breeding smallholders—was a common traditional practice worldwide. For instance, swill (i.e., cooked food waste mixed with water for feeding to pigs) is believed to have been used since the domestication of wild pigs [89]. Over the past

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decades, food crises associated to animal disease outbreaks, such as the outbreaks of foot-and-mouth disease, bovine spongiform encephalopathy, and the identification of dioxins in feeds, had led several countries to severely restrict the utilization of catering waste as animal feed due to the risk of contamination, with the EU being one of the most pronounced cases, with its Animal by-products Regulation 1774/2002 [97] to be revised by Regulation 1069/2009 [98]. These regulations permit the use of food waste as feed for farmed animals only if it can be demonstrated that there is no risk of their contamination with meat, fish, or other animal products. This practically excludes all food waste from households and the food service sector, often termed as catering waste, allowing only the use of a small fraction of food waste. Catering waste could still be used, under specific treatment conditions, for the feed of fur animals and pets. In addition, all animal feed shall fulfill the hygiene requirements set in the Directive 2002/32/EC, on undesirable substances in animal feed [99]. Sampling and control of the feed shall include testing for the following parameters: nitrites, mycotoxins, pesticides, heavy metals, microbiological factors, and physical contaminants. Lately, some progress has been made toward the relegalization of upcycling food waste, other than catering waste, through livestock in the EU. In the Catalogue of Feed Materials (Regulation EU No. 2017/1017), the term “former foodstuff” was introduced, recognizing the capacity of food waste to be converted to feed. According to the catalogue, former foodstuffs are defined as “foodstuffs, other than catering reflux, which were manufactured for human consumption in full compliance with the EU food law but which are no longer intended for human consumption for practical or logistical reasons or due to problems of manufacturing or packaging defects or other defects and which do not present any health risks when used as feed.” Recently the European Commission provided guidelines regarding the conversion of food to feed, clarifying that [100] (i) products of nonanimal origin, which do not consist, contain, or are contaminated with products of animal origin, may either directly become feed, within the definition and scope of Regulation 178/2002 [101], provided they are by-products of food manufacturing processes, or be classified as waste, within the definition and scope of the Waste Framework Directive (2008/98/EC), before becoming feed, in which case, under conditions, they can still be processed for feed production; and (ii) products of animal origin or contaminated with animal by-products are classified as animal by-products within the definition of the animal by-product legislation; then, subject to the rules laid down in ABPR and in the transmissible spongiform encephalopathy regulation (999/2001), they may become feed (for pets and fur animals). As a result of the aforementioned regulation regime, only a small portion of food waste generated in the EU is currently upcycled as animal feed. The European Former Foodstuff Processors Association (EFFPA) estimated that about 3.5 million tons per year of former foodstuffs are processed into animal feed in the European Union. This quantity could grow up to 7 million tons by

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2025, given the ever-growing development in processing techniques and the expansion to other food chain sources [102], which still falls far from the total food waste quantity in the EU, of about 88 million tons [41]. A change in the EU legal framework that would expand the options for upcycling food waste through the production of animal feed may pose remarkable environmental benefits for EU member states [89]. It would also be an effective tool to address the food waste generation challenge through proper management. However, as indicated by Salemdeeb et al. [93], it cannot be successfully completed unless it is supported by all stakeholders in the animal feed sector (i.e., policy makers, feed producers, animal breeders, and consumers) and backed by an effective source separated food waste collection system. Although in the EU the conversion of food waste to animal feed is subject to very strict regulatory restrictions, in other parts of the world, particularly in East Asia, it is promoted and/or established by central authorities, without compromising health and safety. Japan has developed and implemented concrete policies to address the food waste and loss issue since 2000 [103]. The “Promotion of Utilization of Recyclable Food Waste Act” (usually referred to as “Food Waste Recycling Law”) came into force in 2001 to support food waste reduction and their recycling to compost and feed [89, 103–105]. The feed derived from food waste has been called “Eco-feed” [104]. The Food Waste Recycling Law was amended in 2007 and (again) in 2015, as to set the conversion of food waste into animal feed as a more favorable option compared with composting and incineration and to encourage the development of certified business clusters, known as “recycling loops,” which would exchange food waste and products derived from food waste [104, 105]. Furthermore the Japanese government has introduced two certification systems, one for “Eco-feed” and another for soil amendments (compost) produced from food waste and the agricultural products produced with the addition of the aforementioned soil amendments [104]. Similar policies have been developed and implemented in South Korea and Taiwan, resulting in the conversion of over 40% of their food waste into feed [89, 96, 106]. Since the early 1990s South Korea has introduced a series of regulations, such as the Mandatory Food Waste Act, the Control of Livestock and Feed Act, and the Prohibition of Waste Emission law, which progressively led to high rates of food waste recycling: it is roughly estimated that 95% of the generated food waste is recycled into animal feed, fertilizer, and methane gas or solid fuel. More specifically, feed and fertilizer from food waste account for approximately 90% of the food waste recycled [107]. Up to 2017 there existed 240 licensed food waste processing facilities in South Korea, 115 of which focused on feed production and 86 on fertilizer production [107].

5.2 Toward Animal Feed From Food Waste To improve the efficiency of the conversion of food waste into animal feed, three main challenges have to be addressed: (i) issues of animal welfare and public health protection for humans; (ii) the inherent characteristics of food

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waste (i.e., variation in composition and sources and high moisture content); and (iii) the fate of the final product [90]. Contamination risks associated to animal feed from food waste have been restrained by regulatory frameworks and the implementation of proper processing methods, such as heat treatment, heat drying, and pasteurization [89, 90]. The final “recipient” of the feed, i.e., the species fed, has a determining role on the magnitude and possibility of contamination risk. For instance, providing feed form food waste to fish, rather than farm animals, diminishes the risks for public and animal health [96]. Variations in composition and sources of food waste hinder, to an extent, the standardization of the conversion process and the uses of the generated feed. In spite of these challenges, even in the EU, an area with particularly stringent food and feed regulations, a significant number of stakeholders in both the animal feed production and food waste management industries are working toward a better exploitation of food waste for animal feed production. Indicatively a good example at demonstration scale is the implementation of the EU cofunded LIFE project “Food for Feed: An Innovative Process for Transforming Hotels’ Food Waste into Animal Feed (F4F)” in Greece. The project aims the conversion of food leftovers from the hospitality sector into a highquality product that can be directly used as dietary supplement for animal feed, through solar drying. It investigates health and safety issues, as well as legislation and market barriers. Interestingly an EU project was funded to investigate and demonstrate the safety and overall environmental and economic feasibility of a practice currently prohibited in the EU, in the light of providing better information to the relevant discourse.

6 CONCLUSIONS AND PERSPECTIVES Stakeholders in the FSC accord to the fact that the main obstacles in addressing the food wastage challenge and closing the food loop is the lack of a universal definition, reliable baseline data, proven and efficient management options, and public awareness along the whole FSC. Thanks to the efforts of many pioneering stakeholders in the sector, from international organizations and policy makers to large retailers and nonprofit organizations, and a series of cutting-edge research projects, such as FUSIONS and REFRESH funded by the EU, remarkable progress has been made in the field. A common definition could facilitate and validate quantification, monitoring and evaluation of food waste prevention, and management interventions. Furthermore, to tackle food wastage, the boundaries of the conventional food waste management schemes should be extended, as to embrace the mechanisms of the surplus food generation and redistribution. Under the lens of the circular economy concept, the development and establishment of holistic and cross-disciplinary management schemes to address food surplus and waste based on sustainable food production and consumption models are required. These schemes would serve as benchmarks for policy makers, facilitate the development of awareness raising strategies and

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campaigns, enhance food donation, and support industrial synergies. For their development, regulatory and operational reforms are needed to overcome legislation shortcomings and/or gaps (such as donor liability or overregulation of food for feed utilization) and go beyond conventional business models.

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Chapter | Five

Food Waste Composting: Challenges and Possible Approaches Ammaiyappan Selvama,b,c, Xuan Wanga,c, and Jonathan Wonga,c Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinaa Department of Plant Science, Manonmaniam Sundaranar University, Tirunelveli, Tamil Nadu, Indiab Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinac

1 INTRODUCTION 1.1 Global Food Waste Scenario About one-third of food produced for human consumption is lost or wasted globally through the whole food chain, which amounts to about 1.3 billion tons per year as estimated by Food and Agricultural Organization [1] or can be up to 2 billion tons as reported by a study of Institution of Mechanical Engineers [2]. The upstream stages including production, postharvest handling, and storage represent 54% of total wastage and are considered food losses, while downstream stages including processing, distribution, and consumption represent 46%, which are considered as food wastes [1]. The monetary value of the wasted foods is estimated to be about 1 trillion USD when accounting the social and environmental costs [3]. In industrialized countries the per capita food wastage is about 95–115 kg/year, which is several times higher than the developing countries such as sub-Saharan Africa and South/Southeast Asia, where the per capita waste generation is 6–11 kg/year [4]. Food industries are blossoming through the developing urbanization. However, many food processors are facing problems of managing the solid wastes produced during the food processing. 137 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00005-1 Copyright © 2021 Elsevier Inc. All rights reserved.

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Global municipal solid waste (MSW) production was about 2.01 billion tons during 2016 and estimated to be around 3.4 billion tons by 2050 [5], of which 44% were organic and putrescible whose main source could be the pre- and postconsumer food waste from the households, institutions, and industries. In Hong Kong, 3662 tons/day of food waste, representing 34% of the MSW, was generated in 2017. Domestic food waste disposal rate was 0.32 kg/person/day, while commercial and industrial (C&I) food waste disposal rate was increased from 0.17 kg/person/day in 2016 to 0.18 kg/person/day in 2017, which is partly linked to the vibrant local economy [6]. In the past years, most of the food wastes were landfilled, but environmental regulations, limited landfill sites, and higher tipping fees are forcing the consideration of other options [7].

1.2 Composting Composting, one of the most important treatment methods for solid wastes, provides a means to reduce the amount of wet organic materials discarded into landfills, reduce costs associate with disposal, remove toxic substances, reduce the load of pathogenic organisms, and recycle the waste to a potentially beneficial material having commercial value [8–13]. Composting is a process in which the naturally occurring ability of organisms to recycle organic waste is used for the benefit of humans in an accelerated degradation of organic waste [14]. The end product, called compost or humus, could act as a conditioner for soil. In the process of composting, microorganisms break down organic matter and produce carbon dioxide, water, heat, and humus, the relatively stable organic end product, as shown in Fig. 1. Under optimal conditions, composting proceeds through three phases: (1) the mesophilic or moderate-temperature phase, which lasts for a couple of days; (2) the thermophilic or high-temperature phase, which can last from a few days to several months; and finally (3) a several-month cooling and maturation phase (Fig. 2). Different communities of microorganisms predominate during the various composting phases. Initial decomposition is carried out by mesophilic microorganisms, which rapidly break down the soluble, readily degradable compounds. The heat they produce causes the compost pile temperature to rapidly rise. As the temperature rises above about 40°C, the mesophilic

FIG. 1 Aerobic composting process of organic materials.

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FIG. 2 A typical temperature profile during composting. Adopted from J.W.C. Wong, X.Y. Wang, A. Selvam, Improving compost quality through controlling nitrogen loss during composting. In: J.W.C. Wong, R.D. Tyagi, A. Pandey (Eds.), Current Developments in Biotechnology and Bioengineering, Book 5: Solid Waste Management, Elsevier Publications, 2017, pp. 59–82 (Chapter 4).

microorganisms become less competitive and are replaced by others that are thermophilic or heat-tolerating microorganisms. At temperatures of 55°C and above, many microorganisms that are human or plant pathogens are destroyed. Because temperatures over about 65°C kill many forms of microbes and limit the rate of decomposition, compost facilities use aeration and mixing to keep the temperature below this point. During the thermophilic phase of composting, high temperatures accelerate the breakdown of proteins, fats, and complex carbohydrates like cellulose and hemicellulose, the major structural molecules in biomass. Once the supply of these high-energy compounds becomes exhausted, the compost temperature gradually decreases, and mesophilic microorganisms once again take over the final phase of curing or maturation of the remaining organic matter. High temperature in composting during thermophilic phase could effectively kill pathogens, eggs, and plant seeds in waste to make compost a safe organic product.

1.3 Composting Requirements The main objectives of composting are to decompose organic fraction of waste to a stable condition; reduce its volume, weight, and moisture content; minimize potential odor; destruct pathogen; and increase the availability of potential nutrients for agricultural application [15]. Utilization of organic matter by the microbes and eventual stabilization of organic matter are accelerated when composting environment is suitable for the microbes. Therefore factors affecting the performance of microbes will affect the composting performance. To achieve an efficient composting to obtain a stable and

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mature compost, the following factors should be considered and controlled during the composting process. Moisture content: Moisture is the medium through which the microbes obtain their nutrients and oxygen. Therefore the compost should be maintained neither be too dry nor too wet; the latter condition will establish the anaerobic conditions by preventing the entry of air through the composting mass. Moisture content maintained in the range between 40% and 60% in the compost pile is suggested for the good composting. Bulk density: Bulk density of the feedstock mix affects the aeration and the available free air space (FAS) in the compost pile. Moisture content and particle size of the feedstock materials significantly influence the bulk density. Generally a bulk density of 550 kg/m3 is considered optimum due to the effective availability of FAS facilitating sufficient air flow. Therefore the particle size and moisture content should sufficiently be adjusted to achieve an ideal bulk density of, especially, the initial composting mass. C/N ratio: Microbes have specific nutrition requirements, of which the ratio between carbon (C) and nitrogen (N) is considered important in composting process. Carbon is the energy source, while protein is important for cell differentiation. The optimal initial C/N ratio of the composting mass should be in the range from 25 to 35. During composting, the C/N ratio declines to a lower level due to the use of carbon for energy and nitrogen assimilation. Oxygen: Adequate oxygen availability ensures biological processes to thrive with optimum efficiency in the compost pile. An oxygen content of 12%–15% is considered essential for the composting. Aeration affects temperature, moisture, carbon dioxide and oxygen content of the air in the pile, and the rate of removal of potentially toxic gasses. Temperature: During composting, temperature increases as a result of microbial activity, and a suitable insulation and control of the temperature between 55°C and 65°C is a prerequisite for efficient and rapid composting. However, temperature >70°C will kill potential microbes and is considered inhibitory to the microbial degradation. pH: It is one of the critical parameters of composting; especially a low pH would result in odor that affects the application of composting itself. A pH range between 6.0 and 7.5 is optimal for composting bacteria. If the feedstock has low pH, adjusting pH of the composting mass initially and during the composting process is required. Providing an ideal environment considering the above parameters would facilitate a rapid and efficient decomposition of organic matter and also enables to achieve pathogen-free and weed seed–free compost.

2 FOOD WASTE PROPERTIES Composting technologies with varying levels of sophistications have been developed in the last five decades for the treatment of a variety of biowastes such as sewage sludge and animal manures [16–20]. Despite the fact that the

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basic scientific principles underlying the composting have been studied and understood for many years, food waste is a relatively new feedstock and posing challenges mainly because of its properties. Food waste has some limitations as a raw compost feedstock due to its high moisture content, low C/N ratio, high fat or oil, high bulk density, and the significant quantities of easily degradable organic matter. The key composting-related properties of the food wastes are presented in Table 1. Moisture content of the food wastes ranges 55%–90% according to the source and the nature of generation. The organic fraction of the municipal solid waste (OFMSW) was reported to have a moisture content of
67% [21], and source-segregated domestic food wastes have a moisture content of
75% [22], while the food wastes from restaurants and canteens generally have a high moisture content ranging from 75% to 82% [23–25]. In majority of the cases, the moisture content is not within the optimum range for composting. Moreover a higher moisture content would always result in a higher bulk density value more than the optimum value required for composting. Therefore the food wastes must be mixed with other low bulk density, dry materials as is practiced for other biosolids such as animal manures. The C/N ratio is an important factor affecting the composting process and compost quality. The C/N ratio of food wastes ranges from 7.5 to 18.5, much lower than the optimum values recommended for the composting process.

TABLE 1 Selected Properties of Food Wastes. Parameter

Value

Moisture content (%)

55–80

Organic matter (%)

75–98

3

Bulk density (kg/m )

706–860

pH

4.6–6.6

Total organic carbon (%)

45.5–58.8

Total nitrogen (%)

1.9–6.7

C/N ratio

7.5–18.5

Carbohydrates (% OM)

36

Proteins (% OM)

21

Fats (% OM)

15

Source: Data from J.W.C. Wong, A. Selvam, M.K. Awasthi, Composting for organic waste management. In: J.W.C. Wong, R.Y. Surampalli, T.C. Zhang, R.D. Tyagi, A. Selvam (Eds.), Sustainable Solid Waste Management, ASCE Publication, USA, 2016, pp. 233–273 (Chapter 9); E. Epstein, Industrial Composting: Environmental Engineering and Facilities Management, CRC Press, Taylor and Francis Group, LLC, Boca Raton, 2011, p. 314. ISBN: 978-1-4398-4531-8; H. Fisgativa, A. Tremier, P. Dabert, Characterizing the variability of food waste quality: a need for efficient valorisation through anaerobic digestion, Waste Manag. 50 (2016) 264–274.

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Therefore it is necessary to mix the food waste with bulking agents having high C such as sawdust and straw to adjust the C/N ratio [15]. However, when large pieces of wood pieces or chips are used as bulking material, a high initial ratio should be favorable as the woody materials do not degrade much during the active period of composting. A low C/N ratio can lead to N loss through ammonia (NH3) volatilization [26–28]. The pH is another critical parameter influencing both the efficiency of composting process and odor potential. The pH of the food wastes were generally acidic ranging from 4.6 to 6.6, often well below the optimum range. Volatile fatty acids (VFAs) are generated in significant quantities during the fermentation of carbohydrates and fats in the composting mass. Volatile fatty acids decrease the pH of the composting mass leading to retarded decomposition efficiency. The most common approach to control this acidity is the addition of alkaline materials [29–31]; in turn, use of high quantities of alkaline materials could be inhibitory to the microbes and results in nitrogen loss from the composting mass [15, 31–33]. Thus controlling the pH during the composting process and nutrient loss in the form of ammonia are the key challenges of food waste composting, while other issues are similar to that of other biosolids used in composting. Furthermore the food wastes from the Asian countries, especially the Chinese region, were reported to contain a high level of oil and fats (15%–40%), which also seriously affect the physical structure of the composting mass during the process. The high content of fats and oils is very critical in decentralized community-level composters rather than centralized industrial scale operations.

3 CONTROLLING THE ACIDITY DURING COMPOSTING Food wastes contain very high organic matter (volatile solids) content ranging from 75% to 98% (Table 1), of which a significant portion is easily degradable [34]. This fraction is very significant when postconsumer waste is included. Quantity of VFAs constitutes approximately 25% of dry matter of composting mass at the start of the experiment [30]. When the food wastes are composted, the easily available organic matter is degraded rapidly during the early phase of composting resulting in the generation of high quantities of organic acids that reduce the pH of the composting mass to as low as 4.0 [29, 31, 35–39]. The presence of organic acids with low pH values (less than 5) adversely affects the degradation rate of compost due to the inhibition of microbial growth and severely retards the composting process. Volatilization of odorous compounds with acidic nature, e.g., VFA, hydrogen sulfide, and phenols, may increase at low pH [40, 41]. The sensitivity of microbes to undissociated acid also increases as the temperature rises [34]. Despite the acidic conditions the temperature increases during the initial phase of composting, reaching a stage known as “thermoacidophilic,” which subsequently inhibits both the mesophilic and thermophilic microbes. Without sufficient microbial activity the decomposition process is retarded, which eventually leads to failure of composting [32, 42].

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Lin et al. [43] used an open top container aerated with negative pressure by vacuum to compost food wastes and observed an increase in temperature above 65°C within a day despite the decrease in pH from 5.2 to 4.3. D’Imporzanoa et al. [44] reported that although the oxygen concentration in the biomass free air space was kept optimal (O2 > 140 mL l1, v/v) during composting, strong anaerobic conditions developed, as evidenced by the high levels of sulfur compounds, methane, and hydrogen in the outlet air stream. Dynamic respiration of microbes was linked to the release of odor molecules in their study. Hence, it could be assumed that the inhibition by the low pH due to organic acids is not the sole factor controlling composting process. Sun et al. [45] developed a stepwise-cluster microbial biomass inference model to evaluate the nonlinear relationships among variables and microbial activities during composting. These authors demonstrated that pH exerted a least influence on the mesophilic bacteria but a significant influence on the thermophilic bacteria. However, thermophilic microorganisms tolerated the inhibitory effects of organic acids better than mesophilic microorganisms in compost under thermophilic and acidic conditions [42]. Furthermore, they reported that butyric or lactic acid alone and the combination of butyric, lactic, and propionic acids significantly inhibited the growth of thermophilic bacteria. Similarly, Yu et al. [46] reported that butyric and propionic acids showed the maximum inhibitory effects on the growth of thermophilic bacteria.

3.1 Addition of Alkaline Materials The most common approach to control acidity in composting reactor is by the addition of alkaline materials such as lime, magnesium oxide (MgO) + dipotassium hydrogen phosphate (K2HPO4), and sodium acetate [29–31, 47–49]. Among these substances, most used alkaline material was the lime; however, high concentrations of lime can be inhibitory to the microbes. For example, respiration of microbes was completely suppressed in samples with 10% lime, where pH remained high during the 70-h incubation period [30]. When incubated at 35°C, the inhibition was observed with both 5% and 10% lime addition, whereas at higher temperature (48°C) samples amended with 5% lime consumed five times more oxygen compared with samples without addition of lime. This was linked with a near-neutral pH after 40- and 70-h incubation, while the pH of the control samples was very low. During subsequent composting with 5% lime, a similar trend in initial drop of pH was observed. They concluded that 5% lime addition was ideal for the composting of sourceseparated organic waste. However, Wong et al. [31] reported that 3% industrial grade lime was good enough to compost the food wastes using sawdust as bulking agent (Fig. 3). They also reported a steep increase of pH after adding the lime and the pH dropped rapidly to around 7 within 3 days. In addition, they also reported that a combination of coal fly ash and lime having alkalinity equivalent to 1.88% CaCO3 showed almost similar effects with 3% lime addition. Their study demonstrated the use of coal fly ash to adjust the pH of composting mass

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pH

10 8 6 4 2 0 0

Cumulative CO2 loss (g/kg VS)

(A)

20

30

40

50

30

40

50

Day

350 300 250 200 150 100 50 0

(B)

10

0

10

20 D ay

FIG. 3 Effect of lime and coal fly ash (CFA) on the changes of pH (A) and cumulative CO2 loss (B) during composting of food wastes with lime and coal fly ash. (♦, control; , lime 1.5%; ▲, lime 3%; ◊, CFA 5% + lime; □, CFA 10% + lime; and Δ, CFA 15% + lime). The alkalinity of all the combinations of CFA + lime and 3% lime was equivalent to 1.88% CaCO3.

▪

Adopted from J.W.C. Wong, S.O. Fung, A. Selvam, Coal fly ash and lime addition enhances the rate and efficiency of decomposition of food waste during composting, Bioresour. Technol. 100 (13) (2009), 3324–3331.

[31]. However, when the pH increased above 11.0, the ammonia in composting mass become volatile which subsequently affect the nitrogen transformation during composting and nitrogen loss from the system. Earlier, addition of 20% fuel (bottom) ash to source-separated catering waste and an effective composting was reported by Koivula et al. [50]. The ash was obtained from a small district heating plant that used wood chips, sod peat, and residues from plywood industries and waste-derived fuel as fuel. The waste fuel was mainly composed of packaging material including paper, cardboard, and plastic collected from offices. An et al. [51] reported that addition of coal ash, freshly collected from the lagoon, and uric acid to a simulated food waste facilitated effective composting. They have used lagoon ash nearly 1.2 times of the weight of food waste on dry basis. Comparing the quantity of ash added in these two studies indicates that the coal fly ash was effective in small quantities. The successful use of coal fly ash in composting of sludge, manure, and other feedstocks has also been reported in the

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literature but is not considered here. Using the coal fly ash is a challenge since it contains heavy metals, and in such a case, use of less quantity fly ash should be recommended. Addition of sodium acetate in composting process led to an increase in pH level from 5.2 to 5.5 [49]. In addition, the authors have also reported that the sodium acetate was an effective amendment for inhibiting the production of propionic and butyric acids, which counteracts the adverse effects of accumulating organic acids during the composting process. However, there was no difference between the treatments with and without sodium acetate addition on alleviating the pH for about 10 days after the addition. Additional availability of sodium acetate could have encouraged the growth and multiplication of microbes in the composting mass. In a further study, it was observed that sodium acetate, although not effective as lime or other buffering agents like K3PO4 and Na2CO3 in adjusting the pH, resulted in largest thermophilic bacterial population among these alkaline agents [46]. Probably, these results indicate that the acetate could have acted as an easy carbon source resulting in microbial growth; however, impact on pH may not be significant. To induce struvite formation and to exploit the buffering capacity, Wang et al. [47] added magnesium oxide (MgO) and dipotassium hydrogen phosphate (K2HPO4) in 1:1 and 1:2 M ratio to food waste during composting. Addition of K2HPO4 (0.1 M/kg) buffered the pH of the composting mass in a narrow neutral range of 6.8–8.7, which ensured the optimum pH level for the microbes as evidenced from the temperature and CO2 evolution profile (Fig. 4) and struvite formation, indicating K2HPO4 was also a good buffering reagent when the quantity was appropriate. However, addition of K2HPO4 significantly increased the electrical conductivity (EC) to 6.14 mS/cm, when compared with lime indicating a possibility that this compost could exert inhibitory effect on the plant growth. The use of alkaline substances during food waste composting to adjust the pH appears to meet the demands in terms of pH control. However, when the concentrations of alkaline substances are higher than the requirement, it may increase the pH to a level that facilitates the volatilization of ammonia resulting the odor and nutrient loss from the composting mass.

3.2 Microbial Inoculation Inoculation of microbes that efficiently degrade the organic acids is being considered as an option to overcome this organic acid associated with low pH [52, 53]. Choi and Park [54] demonstrated that thermophilic yeast could be used to consume the organic acids and establish suitable pH for the other thermophiles. They observed early proliferation of the yeast Kluyveromyces marxianus Y60 for about 2 days probably scavenging on the organic acids resulted in a suitable environment for the thermophilic bacteria whose population started to increase after 2 days. However, after 2 days, the yeast population declined possibly due to high temperatures although the exact reason was not identified. Similarly, use of another yeast Pichia kudriavzevii RB1 to scavenge the organic

FIG. 4 The changes of temperature (A), CO2 evolution (B), pH (C), and EC (D) during food waste composting. C-control, L-lime 2.25%, P1-Mg:PO4 1:1 ratio and P2-Mg:PO4 1:2 ratio. Data represent the mean of three replicates, and the error bars are standard deviation. Adopted from X. Wang, A. Selvam, M. Chan, J.W.C. Wong, Nitrogen conservation and acidity control during food wastes composting through struvite formation, Bioresour. Technol. 147 (2013), 17–22.

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acids and increase the pH to neutral range within 2 days was demonstrated when composting dog food as a representative for food waste [55]. These authors also observed that the yeast died once the temperature increased to the thermophilic range. To avoid losing the yeast function, in a subsequent study, Nakasaki and Hira [56] extended the temperature of 40°C to remove the acetic acid produced during the initial phase and achieved an effective removal of organic acids that subsequently accelerated the composting process. Thus temperature control as a strategy to remove the organic acid was demonstrated. The fresh raw food wastes do not contain enough microbial population, but the situation could be different if the food wastes were stored for some time, for example, during transportation to the composting plant, resulting in the anoxic fermentation with acid production especially acetic and lactic acid. The lactic acid dominance in the food waste appears to influence the composting in a positive way although through an indirect mechanism. Inoculation of the raw compost with the lactic acid bacterium, Pediococcus acidilactici TM14, isolated from the initial acidic period, accelerated the composting process by alleviating the low pH [57]. The TM14 produced lactic acid at high concentration while inhibiting the production of acetic acid. Since acetic acid is toxic, the reduction in acetic acid concentration due to the production of lactic acid facilitated the development of fungus such as Paecilomyces sp. QH1, which consumed organic acids, increased the pH, and provided a better environment for the thermophilic bacteria. Instead of a single organism, a microbial consortium capable of synergistically degrading organic acids has also been used as an inoculum to improve the efficiency of food waste composting [58, 59]. The microbial consortium originated from the initial phase of food waste composting when the pH of the composting material was maintained in a range of 4–5 for 1 month. Due to the inoculation, no initial pH drop of the composting mass was observed resulting in effective and rapid consumption of the produced organic acids. In addition, the inoculation of microbial consortium was reported to promote degradation of simple proteinaceous compounds and formation of complicated humic-like substances. Sundberg and Jonsson [37] suggested that use of 24% starting culture consisting of active compost could efficiently prevent low pH conditions in a fedbatch composting of food waste, implying the possibility of using premature compost as the bulking agent, as well as the microbial inoculation; however, the effects were inconsistent. Microbial inoculation was reported to increase the content of organic acid at the initial stage of MSW composting [60] due to additional decomposition of organics by the inoculated microorganisms; however, it can be speculated that the microbes might be specialized in production rather than consumption of organic acids, which was not clarified in that report. The consumption of the organic acids by specialized groups of microbes would increase the pH for the growth of other microbes as well. However, recycling mature/premature composts to mix at 24% with the feedstock reduces the rate of processing, thus economically disadvantageous.

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The sensitivity of different microorganisms to the organic acids, low pH, and temperature varies, which influences the composting performance. Generally, bacteria are more sensitive to acids than fungi [61, 62]. Similarly, inhibition of microbes varies between mesophilic and thermophilic temperatures with respect to pH, type, and concentration of organic acids and other environmental conditions. Due to these differential responses and observed inconsistent performances, the use of selective microbial inoculation is still in the developing stage, although some commercial, yet uncharacterized inoculum exits. Overall, rather than individual organisms, a consortium of microbial population complementing each other to scavenging the organic acid may be useful and practical.

4 NITROGEN LOSS AND ITS CONTROL MEASURES 4.1 Nitrogen Dynamics in Composting Mass Nitrogen transformation is a complex process involving mineralization of organic nitrogen, ammonification, nitrification, denitrification, and leaching of inorganic nitrogen (Fig. 5). Mineralization of organic nitrogen is an extremely important step, because it is the first step that commits nitrification. Ammonium is produced by the microbial degradation of organic matter containing nitrogen in food waste, such as proteins, polypeptides, and amino acids. Some of the ammonium released from the ammonification process will be utilized as nitrogen source by microorganisms through immobilization to constitute their own cells, while some nitrogen will be the substrate for further nitrification and denitrification processes. During composting of organic wastes, nitrogen loss via NH3 could

FIG. 5 Transformation of nitrogen during composting. Adopted from J.W.C. Wong, X.Y. Wang, A. Selvam, Improving compost quality through controlling nitrogen loss during composting. In: J.W.C. Wong, R.D. Tyagi, A. Pandey (Eds.), Current Developments in Biotechnology and Bioengineering, Book 5: Solid Waste Management, Elsevier Publications, 2017, pp. 59–82 (Chapter 4).

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amount up to 50% of the initial total nitrogen content [33]. The ammonium will be volatilized as NH3 in the initial thermophilic phase during composting process due to the high pH and high temperatures pushing the balance of NH3/NH+4 toward NH3 emission. Nitrification is the process by which nitrifying microorganisms transform ammonium to nitrate. This is a two-step biochemical process that is catalyzed by two different groups of microorganisms. NH3 is oxidized to nitrite (NO 2 ) by ammonia-oxidizing bacteria or archaea (AOB and AOA, respectively),  whereas NO 2 is further oxidized to nitrate (NO3 ) by nitrite-oxidizing bacteria (NOB). Ammonia oxidation is thought to be the rate-limiting step for nitrification in most systems as nitrite is rarely found to accumulate in the environment [63, 64]. Nitrification is usually rare in the thermophilic phase since nitrifying microbial activity is significantly inhibited under high concentrations of NH3 and high temperature resulting in NH+4 accumulation, which leads to NH+4 loss [65, 66]. Although composting is an aerobic biochemical process, anaerobic conditions still can exist [67], which result in denitrification occurring during composting [68]. In the anaerobic zone or the particle core with lower O2 concentration,  denitrification leads to NO 3 or NO2 being reduced to N2 (Fig. 5). In addition to N2 formation, N2O, NO, and NO2 may also be produced under conditions that are not completely anaerobic [69]. Nitrogen loss during the composting process occurred in three main ways [70]: (1) NH3 volatilization under high pH and high temperature representing 46.8%–77.4% of the total nitrogen loss, which occurs mainly in thermophilic phase; (2) water-soluble nitrogen leached with the seepage water that accounts for the loss of 9.6%–19.6% of the initial total nitrogen, in which 76.5%–97.8% was ammonium nitrogen (NH+4 -N); and (3) under hypoxic conditions, denitrification could lead to 8 [70, 76–78]. A high positive correlation also exists between NH3 volatilization and pH, when the pH is less than 8, and therefore N loss can be effectively reduced by controlling temperature and pH to a certain level [79].

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4.2.2 CARBON/NITROGEN RATIO C/N ratio is an important factor affecting the composting process and compost quality. Imbalance in the required C/N ratio can lead to N loss through NH3 volatilization [26, 80, 81]. The C/N ratio is roughly proportional to the balance between the overall energy contained in the compost (C content) and the principal nutrient needed to decompose it (N content). Higher C/N ratio than the ideal ratio of 25–30 could result in less NH3 volatilization; however, the insufficient N for the mineralization of the carbon would reduce the rate of degradation. In contrast the C/N ratio less than 25 would result in more N loss as there is not enough C that facilitates the immobilization of N [33]. 4.2.3 AERATION RATE Many studies have focused on the effects of different air flow rates to reduce the N loss. Ammonia emission is positively related to air flow, and decreasing the air flow rate, particularly during the thermophilic phase, is an option for reducing NH3 loss [82]. De Bertoldi et al. [83] found that N loss was greater with turning (18% N loss) than with forced aeration (5% N loss). Moderate aeration resulted in lower ammonium volatilization [84]. Lower aeration rate can reduce the volatilization of NH3, whereas the generation of CH4 increases, and the decomposition of organic matter was delayed or prolonged [81]. The orthogonal analysis showed that lignocellulosic waste mixtures with a moisture content of 40% and an aeration rate of 0.4 L/kg dm min1 demonstrated the lowest total nitrogen emission [85]. Besides, properties of composting substrate including particle size, bulk density, and moisture content indirectly influence the efficiency of aeration and exert influence on nitrogen loss. However, considering the optimum conditions for microbial growth, there is not much opportunity to manipulate these conditions, apart from adopting the optimal conditions for composting, to reduce nitrogen loss.

4.3 Approaches to Reduce Nitrogen Loss During Composting 4.3.1 PRECIPITATION OF NITROGEN INTO STRUVITE CRYSTALS Struvite (magnesium ammonium phosphate [MgNH4PO46H2O]) is a phosphate mineral that is formed when Mg2+, NH+4 , and PO3 4 react in 1:1:1 M ratio with a 13 formation constant of 1.41  10 [86]. The equilibrium ion activity product (IAPeq) for struvite is 7.10  1014 [87]. Struvite precipitation is likely to occur if the product of Mg2+, NH+4 , and PO3 4 activities (IAP) exceeds IAPeq. From the exterior view, struvite is a white crystalline substance with a distinctive orthorhombic structure that can be observed in scanning electron microscopy (SEM) and identified via x-ray diffraction (XRD) by matching the intensity and position of the peaks produced to a crystal structure database [88]. Table 2 summarizes selected chemical and physical properties of struvite crystals. Struvite crystals occur spontaneously in various biological media. Precipitation and deposition of struvite were recognized inside pipes and pumps

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TABLE 2 Selected Properties of Struvite Crystals. Parameter

Detail

Chemical name

Magnesium ammonium phosphate hexahydrate

Formula

MgNH4PO46H2O

Aspect

White glowing crystal

Structure

Orthorhombic: regular 2+ PO3 4 octahedra, distorted Mg(H2O)6 octahedral, and NH4 groups all held together by hydrogen bonding

Molecular weight

245.43 g/mol

Specific gravity

1.711 g/cm3

Solubility

Low in water: 0.18 g/L at 25°C in water High in acids: 0.33 g/L at 25°C in 0.001 N HCl; 1.78 g/L at 25°C in 0.01 N HCl

Solubility constant

7.10  1014

Source: Data from X. Wang, Nitrogen conservation by struvite formation during composting process with food wastes (Ph. D thesis), Hong Kong Baptist University, 2015, p. 236.

transporting wastes as early as 1939 [89] and were considered a nuisance due to blocking in the pipes. Therefore a large portion of struvite research has been directed toward the removal and prevention of struvite formation, but struvite was later identified as a premium fertilizer, and research was directed toward the recovery from wastewater treatment industry offering benefit to the industries [88, 90]. Struvite is highly soluble at acidic pH and insoluble at alkaline pH conditions and precipitates in the pH range of 7–11 [91]. Thus its precipitation can be controlled by adjusting the pH and by alteration of supersaturation. Under stagnant conditions (without mixing), at a pH below 8, struvite precipitation proceeds very slowly, indicating an increase in induction time [91]. When pH is between 6 and 11, struvite solubility decreases with increasing pH. However, as pH continues to rise above pH 9, the solubility of struvite begins to increase since the ammonium ion concentration will decrease and the phosphate ion concentration will increase [88]. Supplementation of Mg and P salts to precipitate the NH+4 -N in the composting mass as struvite during composting of biosolids including food wastes [47, 48, 92–97], agriculture residues [98], poultry manure [99], sewage sludge [100], and swine manure [101–105] has gained momentum from the last decade [33, 106]. Jeong and Kim [92] were the first ones to demonstrate the struvite precipitation during food waste composting by adding soluble salts of Mg and P equivalent to 20% of the total initial nitrogen. They observed a pH dropdown to 5.5 during the first 4 days and rose to 8.5 right after that. Considering the N loss, ammonia loss was reduced from 22% to 4.8% of the initial nitrogen with

152

Food Waste Composting: Challenges and Possible Approaches

struvite precipitation, and the final concentration of ammoniacal nitrogen was about 1.43%. In a subsequent study, Jeong and Hwang [93] attempted to completely precipitate the nitrogen by adding Mg and P salts equivalent to 35.4% of nitrogen, which resulted in reduced organic matter degradation, and Mg and P salts equivalent to 20% of total initial nitrogen were found to be optimum. The addition of magnesium and phosphate salts to compost may increase the total salinity of the compost and the orthophosphate content [92], which not only reduces application of the compost for some sensitive plant species but also introduces environment risks due to the possible leaching of dissolved P. Hence the compost products should be thoroughly evaluated in the struvite regime to gain the relevant advantages. In case of food waste, Mg can be a limitation for the formation of struvite. Magnesium chloride (MgCl26H2O) was reported as a good reagent for struvite formation, because of its solubility [107]. However, the salinity of product increased with the addition of excess amount of MgCl2, which inhibited bacterial activity and decomposition of materials [101]. Meanwhile, struvite is sparingly soluble in neutral and alkaline conditions but readily soluble in acid. Struvite precipitation is enhanced when the pH is between 7 and 11 [108] with an optimum range of 7–9 [88]. But during the initial stages of food waste composting, due to the formation of organic acids, the pH may be very low, which would negatively influence struvite formation. MgO and Mg(OH)2 have been recommended as Mg sources due to the additional benefit of increasing the pH to aid in struvite reaction [109], which may be positive during food waste composting. In an effort to identify the ideal supplements, Li et al. [95] compared three different mixtures of Mg and P salts, including K3PO4 + MgSO4, K2HPO4 + MgSO4, and KH2PO4 + MgSO4, and the final NH+4 -N observed in these mixtures were 13.11 g, 19.3 g, and 23.67 g, respectively. However, in terms of gaseous ammonia loss, about 32.8%, 12.6%, and 3.5% of initial total nitrogen were lost in these three treatments in comparison with 21.2% in the control. These authors reported that K3PO4 increased the pH that resulted in high ammonia loss. Ren et al. [102] found that the total nitrogen loss could be reduced from 35% to 12% using Mg(OH)2 and H3PO4 as supplementary salts for pig manure composting. However, because of the insolubility of the material, reaction time was long, residual MgO existed after the reaction, and increasing concentrations of Mg(OH)2 decreased the seed germination index, thus negatively affecting the organic degradation during composting. However, these authors did not report the salinity of the composting mass.

4.3.2 USE OF LIME TO REDUCE THE SALINITY IN STRUVITE-BASED COMPOSTING Previous reports on struvite formation during food waste composting did not consider pH alleviation as a criterion and mainly focused on nitrogen conservation. Therefore considering the acidity problem, MgO and K2HPO4 should be good choices due to their additional benefits of pH buffering capacity and acting

4 Nitrogen Loss and Its Control Measures

153

as a source of Mg and P salts. For example, to achieve nitrogen conservation, Wang et al. [47] added MgO and K2HPO4 to food waste in 1:1 and 1:2 M ratios and composted in 20-L composters. Results indicate that K2HPO4 buffered the pH in treatment 1:2 M ratio effectively in addition to reducing the nitrogen loss from 40.8% to 23.3% of the initial nitrogen. However, electrical conductivity of the compost increased due to the addition of Mg and P salts to >6 mS/cm (Fig. 4) that would hamper the application of the compost, especially to sensitive crops. In case of Mg:P 1:1 ratio treatment, the initial pH of the composting mass could not be alleviated, which also resulted in less degradation, consequently less ammonia emission, and nitrogen loss (Fig. 6). However, this cannot be considered as a suitable composting process. Alkaline materials, such as lime and coal fly ash, are usually used to control pH drops during food waste composting [29–31, 47]. In an attempt to alleviate the low pH and reduce the salinity of the compost product during struvite-based food waste composting, Wang et al. [48] added different doses of lime, 0.75%, 1.5%, 2.25%, and 3%, before adding MgO and K2HPO4 (both at 0.05 M/kg) to the food waste during composting. The results clearly indicated that lime at 0.75% and 1.5% along with MgO and K2HPO4 did not alleviate the low pH and increased the salinity to >6 mS/cm, whereas lime at 2.25% and 3% with Mg and P salts effectively controlled the pH while having an EC of nearly 3 mS/cm at the end of composting (Fig. 7). However, lime alone at 2.25% and 100 Decomposition rate (%, dry weight basis) Nitrogen loss rate (%, of the initial total nitrogen)

80 a a

%

60

a 40 b b

b

20 c

c 0

C

L

P1

P2

FIG. 6 Comparison of organic decomposition and nitrogen loss of the treatments. C-control without supplementation of Mg and P, L-lime addition at 2.25%, P1-Mg:PO4 1:1 ratio, and P2-Mg:PO4 1:2 ratio. Data with the same letter within a parameter are not significantly different (p < 0.05). Adopted from X. Wang, A. Selvam, M. Chan, J.W.C. Wong, Nitrogen conservation and acidity control during food wastes composting through struvite formation, Bioresour. Technol. 147 (2013), 17–22.

154

Food Waste Composting: Challenges and Possible Approaches

3% lime with Mg and P salts resulted in higher ammonia loss when compared with 2.25% lime with Mg and P salts. Thus addition of lime at 2.25% during struvite-based food waste composting was reported to be optimum to reduce the salinity and reduce nitrogen loss by 38% (Fig. 8). In addition, trapping ammonia through struvite formation significantly reduced the maximum odor unit of ammonia from 3.0  104 to 1.8  104 [97]. Lime will compete for the phosphate ions preventing struvite formation and consequently reducing the nitrogen conservation efficiency. Therefore the

FIG. 7 The changes of pH (A) and EC (B) during food waste composting process. L-lime 2.25%, SL0.75-lime 0.75%, 0.05 M K2HPO4 and 0.05 M MgO, SL1.5-lime 1.5%, 0.05 M K2HPO4 and 0.05 M MgO, SL2.25-lime 2.25%, 0.05 M K2HPO4 and 0.05 M MgO, SL3lime 3%, 0.05 M K2HPO4 and 0.05 M MgO. The error bars are standard deviation (n ¼ 3). Adopted from X. Wang, A. Selvam, J.W.C. Wong, Influence of lime on struvite formation and nitrogen conservation during food waste composting. Bioresour. Technol. 217 (2016), 227–232.

4 Nitrogen Loss and Its Control Measures

155

FIG. 8 Ammonia emission (A) and N loss rate (B) during composting process. L-lime 2.25%, SL0.75-lime 0.75%, 0.05 M K2HPO4 and 0.05 M MgO, SL1.5-lime 1.5%, 0.05 M K2HPO4 and 0.05 M MgO, SL2.25-lime 2.25%, 0.05 M K2HPO4 and 0.05 M MgO, SL3-lime 3%, 0.05 M K2HPO4 and 0.05 M MgO. Adopted from X. Wang, A. Selvam, J.W.C. Wong, Influence of lime on struvite formation and nitrogen conservation during food waste composting. Bioresour. Technol. 217 (2016), 227–232.

possible precipitates that can appear when working with solutions containing + 2+ Mg2+, PO3 4 , NH4 , and CO3 are struvite, magnesite (MgCO3), and newberyite (MgHPO43H2O) if lime was added to optimize pH. Struvite precipitates at neutral and higher pH and at Mg/Ca molar ratios >0.6, while newberyite precipitates significantly only at lower pH ( fungal (21%) > animal (18%) > plant (11%) > algal (3%). Lipases exhibit the unique property of catalyzing reactions at the interface of aqueous and a nonaqueous phases [47, 48]. Lipases are capable of catalyzing crucial biochemical reactions, namely, hydrolysis, interesterification, esterification, alcoholysis, acidolysis, and aminolysis. The novel applications of microbial lipases include biopolymer synthesis, production of biodiesel, fat-rich waste effluent treatment, and enantiopure synthesis of pharmaceuticals and nutraceutical agents [47]. The treatment of soybean oil wastes using lipases produced from orange core and frit that mediated transesterification of oil to less toxic products [45]. In another study, bioremediation of waste cooking oil was reported to be conducted by microbial lipases produced by Penicillium chrysogenum using waste grease and wheat bran mix as a substrate [49]. Olive mill waste, which is a lipid-rich waste produced by oil mill industry along with winery waste, was bioremediated using microbial lipases secreted by Aspergillus ibericus and A. uvarum [50]. The use of thermostable lipases in biodiesel production from palm oil and animal fats is also reported [51, 52]. These studies illustrate the crucial role of lipases in FW treatment and the simultaneous production of value-added bioproducts. Besides, lipase action can be one of the effective methods for enhancing AD of FW rich in crude lipids. Major lipids present in FW are animal fat (AF) and vegetable oil (VO), which were reported to be degraded by lipases to release long-chain fatty acid under optimized reaction conditions (RT 24 h, Vol 1000–1500 μL, and temperature 40–50°C). It enhanced biomethane production rate by 80.8%–157.7%, and the digestion time was shortened by 10–40 d [53].

3 PARAMETERS EFFECTING ENZYME ACTIVITY DURING FOOD WASTE TREATMENT Several factors that influence the rate at which enzymatic reactions proceed are enzyme concentration, temperature, pH, total solid concentration, substrate concentration, and inducers and inhibitors (Table 2).

TABLE 2 Factors Affecting Enzyme-Mediated Food Waste Treatment. Enzyme

Vessel Type

Conditions

Product

Hydrolysis Degree

References

Glucoamylase (GA) (0.16% v/v)

500 mL flask with 100 mL working volume

46.3°C, pH 5.2, 4 h, S/L:1 (v/v)

120.1 g/L reducing sugar

NR

[54]

Glucoamylase (170 mg/kg FW)

3 L jar with 1.5 kg working volume

60°C, 100 rpm, 6 h, S/L: 2 (v/v)

67.2 g/L reducing sugar

85%

[55]

Glucoamylase (120 U/g FW)

NR

35°C, pH 5.5, 60 h, S/L: 2 (w/v)

85 g/L reducing sugar

NR

[56]

α-Amylase (NR), GA (1.2 U/g)

NR

50°C, pH 4.5–6, 24 h

55 g/L reducing sugar

NR

[57]

Carbohydrase (8 U/g), GA, cellulase

5 L fermenter with working volume of 3 L

35°C, pH 4.5–6, 9 h, S/L:1 (w/v)

20 g/L reducing sugar

63%

[58]

α-Amylase (120 U/g ds), GA (120 U/g ds), cellulase (8 FPU/g ds), β-glucosidase (50 U/g ds)

NR

95°C pH 5.5, 100 rpm, 1 h and 55°C, pH 5.5, 100 rpm 5 h, S/L:0.2

105 g/L reducing sugar

NR

[59]

α-Amylase (120 U/g ds), GA (120 U/g ds), cellulase (8 FPU/g ds), β-glucosidase (50 U/g ds)

NR

95°C pH 5.5, 100 rpm, 1 h and 55°C, pH 5.5, 100 rpm, 5 h, S/L:0.1

64.8 g/L reducing sugar

NR

[60]

Continued

TABLE 2 Factors Affecting Enzyme-Mediated Food Waste Treatment—cont’d Enzyme

Vessel Type

Conditions

Product

Hydrolysis Degree

References

α-Amylase (10 U/g FW), GA (120 U/g FW)

500 mL flask with 400 g working volume

55°C, pH 4.5, 48 h, S/L:1

131.4 g/L reducing sugar

93%

[61]

Amyloglucosidase (2.0 AGU) and carbohydrases (20.0 FBGU) per 1 g of dry FW

250 mL Erlenmeyer flask with 50 g working volume

50°C, pH 4.5, 150 rpm, 3 h

0.46 g/g FW

NR

[62]

Protease (immobilized Bacillus megaterium), (1 mg trypsin/4 g fish meat)

100 mL Erlenmeyer flask with 50 mL working volume

pH 8, 50°C

50 mg tyrosine/4 g fish meat

30%

[44]

Lipase 5% (orange core and frit), transesterification of soybean oil waste

25 mL falcon tube

72 h

NR

NR

[45]

Lipase (Penicillium chrysogenum) waste cooking oil

NR

pH 8, 40°C

Acid value 26.92 mg/g

55.9%–68.7% increase in acid value

[49]

ds, dry substrate; S/L, solid loading (w/w); NR, not reported.

3 Parameters Effecting Enzyme Activity During Food Waste Treatment

269

3.1 Enzyme Loading Enzymes react with a specific substrate to increase the rate of a chemical reaction within the cell. With increase in enzyme concentration, product formation rate also increases, and the reaction time decreases. However, the substrate must be present in an excess amount, and this reaction is said to be “zero order” as reaction rate will not depend upon substrate concentration. α-Amylase is an important FW-degrading enzyme that acts on starch to produce maltose. To enhance the enzymatic hydrolysis of FW, different dosage (U/g FW) of α-amylase was added with constant glucoamylase of 120 U/g FW for each treatment. Results depicted that the reducing sugar concentration increased sharply for the first 2.5 h with the optimal α-amylase dosage 10 U/g FW. However, with the increasing time, further increase in enzyme dosage did not produce a corresponding increase in the hydrolysis yield [63]. To evaluate the effect of enzyme concentration on the degree of hydrolysis of proteins in the red tilapia (Oreochromis sp.) viscera (RTV), commercial alcalase 2.4 L enzyme was used at different concentrations. The results indicated that increasing the enzyme concentration produced an increase in the DH and in the reaction rate [64]. Plant protease from garlic was applied by varying crude ginger concentration, and the optimum concentration of enzyme was determined at 0.7 mg/mL [65]. Different substrate specificity of the enzyme caused different enzyme hydrolyzing activities. The effects of proteases (trypsin) on the hydrolysis efficiency of protein depicted that the lower the enzyme concentration, the higher the Mw distribution in the high Mw peptide group [66]. Similar effects were observed with lipase activity on lipids, as the enzyme concentration increased, the rate of reaction proportionally increased and fatty acids were observed to be released from triglycerides increasingly faster [67]. Prior to the ethanol fermentation by Saccharomyces cerevisiae, FW hydrolysis to glucose was carried out using individual commercial enzymes (amyloglucosidase and carbohydrase) and optimized enzyme mix. Results depicted that higher glucose yield was obtained with in 3 h when enzyme mix (0.46 g g 1 of dry FW) was used compared with when used individually [62].

3.2 Temperature Rate of an enzyme-catalyzed reaction generally increases with the increase in temperature, but many enzymes are adversely affected by high temperatures (55% cellulose and >25% hemicellulose. Furthermore, optimum NaOH pretreatment conditions were found to be 60°C in temperature and 3 days duration. After pretreatment, Clostridium acetobutylicum was employed for fed-batch fermentation for 60 h using medium composed of concentrated NaOH-pretreated SB, urea, and FeSO4, finalized with sample centrifugation at 6000 g for 5 min. This fermentation process produced 14.17 g/L biobutanol with 21.11 g/L ABE. ABE were obtained from 68.89 g/L sugars in NaOH-pretreated SB hydrolysate. This demonstrated that pretreatment of FW-based substrates could improve butanol production yields. In addition to its role as a biofuel, bioethanol and biobutanol produced from FW valorization can also be used as biosolvent, which is a chemical derived from FW treatment.

4 CONCLUSIONS AND PERSPECTIVES Huge amounts of FW are produced in the world, which can serve as valuable bioresources for production of high-value products while also lowering the carbon footprint. Studies have exhibited the advantageous nutritional traits present in discarded FW and utilization of these available nutrients in biobased conversions. Hence, aside from bioenergy production, many innovative value-added products are being developed from FW valorization. This chapter highlighted how FW conversion into value-added products can be achieved and optimized

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through proper valorization processes. In the near future, it is expected that FW treatment technology will become more advanced, and a wider variation of value-added products will be accessible in both lab-scale and industrial-scale valorization processes.

ACKNOWLEDGMENT The authors gratefully acknowledge the Hong Kong Innovation and Technology Commission for the Innovation and Technology Fund (ITF/176/18).

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[97] K. Walker, P. Vadlani, R. Madl, P. Ugorowski, K.L. Hohn, Ethanol fermentation from food processing waste, Environ. Prog. Sustain. Energy 32 (4) (2013) 1280–1283. [98] C. Moukamnerd, H. Kawahara, Y. Katakura, Feasibility study of ethanol production from food wastes by consolidated continuous solid-state fermentation, J. Sustain. Bioenergy Syst. 03 (02) (2013) 143–148. [99] H. Huang, V. Singh, N. Qureshi, Butanol production from food waste: a novel process for producing sustainable energy and reducing environmental pollution, Biotechnol. Biofuels 8 (1) (2015) 1–12. [100] S.K. Brar, et al., Agro-industrial wastes as feedstock for sustainable bio-production of butanol by Clostridium beijerinckii, Food Bioprod. Process. 98 (2016) 217–226. [101] V. Ujor, A.K. Bharathidasan, K. Cornish, T.C. Ezeji, Feasibility of producing butanol from industrial starchy food wastes, Appl. Energy 136 (29) (2014) 590–598. [102] Z. Qin, G.J. Duns, T. Pan, F. Xin, Consolidated processing of biobutanol production from food wastes by solventogenic Clostridium sp. strain HN4, Bioresour. Technol. 264 (April) (2018) 148–153. [103] L.-W. Du, et al., Butanol production employing fed-batch fermentation by Clostridium acetobutylicum GX01 using alkali-pretreated sugarcane bagasse hydrolysed by enzymes from Thermoascus aurantiacus QS 7-2-4, Bioresour. Technol. 212 (2016) 82–91.

Chapter | Eleven

Conversion of Food Waste to Animal Feeds Kumarasamy Murugesana, Kaarmukhilnilavan R. Srinivasana, Kowsalya Paramasivama, Ammaiyappan Selvamb, and Jonathan Wongc,d Department of Environmental Science, Periyar University, Salem, Tamil Nadu, Indiaa Department of Plant Science, Manonmaniam Sundaranar University, Tirunelveli, Tamil Nadu, Indiab Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinac Institute of Bioresources and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinad

1 INTRODUCTION Food waste is defined as food loss occurring at the end of the food chain, which represents loss of resources such as labor, water, energy, and land used in production along with retailers and consumers. Billions of dollars are spent every year on the production of food and disposal of food waste, which is a problem not only for the environment, but also causes significant economic losses [1]. The annual cost of food waste in the United States is $161 billion, which is 31% of the total US food supply [2]. This amount of food waste contributes around 18% of total methane production from landfill. The Food and Agriculture Organization reports that every year around 1.3 billion tonnes of food, which is almost one-third of the food produced for human consumption, are lost or wasted throughout the entire food chain, from initial agricultural production to final household consumption [3, 4]. Food waste occupies one of the largest portions of municipal solid waste in different countries [5]. Annually, India, Philippines, China and the United States generate approximately 1.81, 6.53, 32.0 and 15.0 million tonnes of fruit and vegetable wastes, respectively [6]. The most important concern regarding food loss is that the unconsumed food is being disposed of in landfill. A study reported that around 95% of the food waste generated in the United States goes directly to landfill, which results in the production of large quantities of greenhouse gases [7, 8], which have a 21-fold higher warming potential than carbon dioxide. Landfill accounts for 305 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00011-7 Copyright © 2021 Elsevier Inc. All rights reserved.

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8% of global greenhouse gas emissions that could be linked to the putrescible waste reaching landfill. Wasting a kilogram of wheat and rice is directly related to wasting 1500 and 3500 liters of water, respectively, used for their production. Almost 250 km3 of water and 1.4 billion hectares of land are lost to produce food that is wasted globally. Reduction of food loss and waste is a serious challenge in India, which needs to feed its rapidly growing population (1.7 billion by 2050). To alleviate the environmental burden of food waste, alternative methods are needed to divert food waste into higher value uses to minimize its environmental impact and promote long-term sustainability of our food supply system. To overcome the existing critical situation of high cost and inadequate supply of livestock feed, use of food waste as an alternative source of animal feed holds tremendous potential. This chapter provides a comprehensive overview of the types of food waste, conversion of food waste to animal feed and its limitations, and advantages and disadvantages of the use of food waste as animal feed.

2 TYPES OF FOOD WASTE Food waste can be classified in several ways based on its nature and the source from which it is derived. Based mainly on its natural resource, food waste can be divided into plant-derived food waste and animal-derived food waste. Similarly, depending on the mode of cooking, food waste may be classified as raw or uncooked food waste, cooked food waste, and semicooked food waste. During the course of food production, food is transferred through various channels from farmer to consumer and waste generation occurs at each of these levels. Agricultural land is at the initial level of the food chain. Hence, farmers are considered to be the primary producers. Warehouses and industries like flour mills and food preserving mills are at the secondary level of the human food chain and can be considered as primary distributors. Since they are producing processed food materials they may also be considered as secondary producers. Markets, hotels, and restaurants are at the third level of the human food chain and are classified as secondary and direct distributors to society. Customers (also called consumers) are the last but superior level of the food chain. Based on this human food chain we can classify food waste as follows: (1) agricultural food waste—produced by primary producers, (2) industrial food waste—produced by primary distributors, (3) market food waste—produced by secondary distributors in raw and uncooked form, (4) hotel and restaurant food waste—also produced by secondary distributors in cooked form, and (5) domestic food waste—produced by consumers. Based on the physical state, food waste can be classified as solid food waste, semisolid food waste, and liquid food waste. Overall, the classification of food waste is explained in Table 1.

2.1 Plant-derived food waste Plant-derived food waste is derived from plant-based resources such as vegetables, cereals, and grains. Hence, it may also be called vegetarian food waste (with a few exceptions like milk products). This food waste is generated due

Types of Food Waste

307

TABLE 1 Classification of Food Waste. Classification of food waste

Based on natural resource

Based on mode of cooking

Plant derived food waste (i) (ii) (iii)

Cereals and legumes based Oil based Vegetables and fruit based

Animal derived food waste (i) Meat products (ii) Fish and seafood (iii) Dairy products (iv) cooked animal food waste

Based on level of human food chain

Cooked food waste e.g.: Sauce, Rice, Breads, etc. . Semi cooked food wastes e.g.: Chutney and intermediates of cooked foods and their remainings

Uncooked food waste: Juice & Salad

Based on physical state

Primary producers –Formers Solid food wastes Primary distributors/ Secondary producers—Food industries and Warehouses Secondary distributors Consumers – Customers e.g.: All the domestic food wastes

Semi solid food wastes Liquid food wastes Markets—Raw and uncooked food wastes Hotels and Restaurants food wastes—Mostly cooked food wastes

to the spillage, damage, and spoilage of edible plant materials during harvesting, transporting, and processing events. It can further be classified into three subcategories: (i) Cereal and legume-based food waste; (ii) Oil-based food waste; (iii) Vegetable and fruit-based food waste. Cooked rice, rice bran, breads, wheat bran, barley and brewers spent grain, and cooked legumes are considered as cereal and legume-based food waste. This type of food waste is mostly produced by distributors and customers. The cakes of oil-extracted seeds produced by oil-extracting mills are an example of oilbased food waste. It is mostly generated by primary distributors (or secondary producers), e.g., sunflower seeds, soybean seed, and olive pomace. Damaged and rotten vegetables and fruits and their leftovers are known as vegetable and fruit-based food waste. Though they are produced at all levels of the food chain, they are mostly produced from secondary distributors such as markets. Fruit and vegetable peel, grape pomace, apple pomace, tomato skin, cabbage, radish and carrot tops, and pomace and all examples of rotten fruit and vegetable food wastes.

2.2 Animal-derived food waste Animal-derived food waste can be defined as the waste products derived from edible animal sources, which can be divided into four subcategories: (1) meat products, (2) fish and seafood, (3) dairy products, and (4) cooked animal food waste. The wastes generated by meat processing industries and retail shops such

308

Conversion of Food Waste to Animal Feeds

as blood, intestines, and nonedible parts of animals are considered as meat product food waste. The fins, gills, and scales of fishes and the leftovers of other marine animals produced by fish markets are considered as fish and seafood wastes. Spoiled milk and spillages from the dairy industries are known as dairy food wastes. Since the nature of cooked food waste greatly varies from the raw and uncooked food wastes mentioned previously, cooked animal-derived food waste can be considered as a separate type of food waste. Spoiled cheese, paneer, and meat bones are examples of this type of food waste.

3 NUTRITIONAL VALUE OF FOOD WASTE The nutritional value of food waste or loss per day has been estimated to be approximately 1200–1500 food calories [8]. Food waste comprises approximately 30%–60% carbohydrates, 5%–10% proteins, and 10%–40% lipids [9]. Food waste results in waste of the nutrients present in discarded foods. Food waste generation (g/capita/day) is categorized as follows: cooked food (56%), vegetables (18%), fruits (16%), dairy (3%), and cereals (4%) [10]. Food waste is generally a nutrient-rich feedstock for animals. Hence, food waste can be used as a replacement in animal feed. It is estimated that 1 tonne of dry food waste could replace the same amount of maize grain to meet the protein requirements of a given animal. Maize, a primary feed source containing 8%–10% of protein, can be replaced by food waste (19.2% protein) [3]. Composting of organic waste with the help of insects has become a recent trend and linked with this is the use of insects for their higher nutritional value for animal food. A well-grown larva of the black soldier fly Hermetia illucens on average accounts for 40%–45% of protein in biomass and up to 35% of fat in dry weight, which shows its suitability for livestock feed. A study conducted on H. illucens revealed the ability of the fly to consume an array of organic wastes, namely poultry feed, pig liver, pig manure, kitchen waste, fruits and vegetables, and rendered fish, while the highest fly biomass production was observed in kitchen waste. The concentration of bioactive compounds and polyphenols in the peel, pomace, and seeds of food waste is twice that of the edible part present in animal feed preparation. These compounds present in food waste exhibit anticancer, antimicrobial, antioxidative, and immune-stimulating effects in vertebrates and also reduce the incidence of cardiovascular diseases [11]. Food waste contains pigments like carotenoids from tomato peel and carrot pomace and anthocyanin from banana bracts, and betalains from beetroot pulp possess antioxidant properties that could be used to protect against oxidative damage in living systems by scavenging oxygen free radicals and also for increasing the stability of foods by preventing lipid peroxidation to the animals [11].

4 FOOD WASTE TO ANIMAL FEED—PROCESSING METHODS The conversion of food waste into a complex animal feed involves a series of processing methods to improve the quality of nutrition, digestibility, feeding

4 Food Waste to Animal Feed—Processing Methods

309

efficiency, removal of toxins, sanitation of pathogens, removal of nonedible materials, feasibility for long-time storage, transportability, and marketability. The conversion of food waste to a value-added product such as animal feed can improve the efficiency of food by reducing the cost of animal feed, which leads to higher profits for farmers and also lowers environmental impacts caused by food waste disposal. For any such conversion process, the processing of foods by altering their physical (and rarely chemical) properties is an essential step to enhance feed quality, stabilize feed in the animal diet, and also minimize loss during feeding. Food waste processing methods mainly focus on feed conversion efficiency, increased feed intake, and cattle health with reduced digestive disorders. Food waste conversion to animal feed can be done using several processing methods such as dehydration and/or drying, pelleting, extrusion, fermentation, silage making, etc. These processing methods are either combined or individually applied to convert a specific type of food waste into a suitable animal feed.

4.1 Dehydration Dehydration is the process of removing water, which prevents microbial growth and preserves food quality. Food waste contains a high fraction of water in its total biomass, which is estimated to be around 80%–90%. The higher moisture content favors microbial growth and enzyme activities leading to the denaturing of food nutrients, which in turn convert the food waste as toxic substances. The moisture content of different types of food wastes are given in Table 2. The National Research Council (NRC, 1998) recommends 10% and 12% of

TABLE 2 Quantity of Water Among Different Food Wastes. Food

Origin

Water Content

References

Restaurant food waste

Florida, USA


60%–75%

[12]

Fresh restaurant food waste

Seoul, Korea

79%

[13]

Potato hash waste

–

85%

[14]

Pumpkin waste

–

91%

Apple waste

Lingbao, Henan

85%

[15]

Mango pulp

–

0.80%–0.85 kg/kg

[16]

Fruit market waste

Yogyakarta, Indonesia

86%

[17]

Sago pith waste

Johor, Malaysia

82%

[18]

Hong Kong

45.0% 22.3% 34.5%

[9]

Bakery waste

Cake Bread Pastry

310

Conversion of Food Waste to Animal Feeds

moisture content to be present in animal feed [19]. The direct drying process not only preserves the food waste, but also offers reduction of weight, which enables packing and easier transportation at low cost [20]. Most of the drying processes occur in two distinct phases, namely the constant rate phase and the falling rate phase. In the constant rate phase, moisture removal remains constant, since the internal moisture transported to the surface is equivalent to the rate of evaporation. In the falling rate phase, moisture is removed at different rates as the product moves to different phases [20]. Drying can be performed by different methods according to the type of food waste and the target animal feed product. In addition to the dryers, other moisture-removing techniques such as centrifugation, flocculation, filtration, and osmosis may also be applied for the removal of liquid from food waste prior to the dehydration process. The dryer is an engineered system that allows drying of food waste in a programmed fashion. In the drying process, moisture is removed by either keeping the material on a hot surface or applying hot air on the material. In centrifugation, the food waste is kept in a rapidly spinning field, which results in separation of the solid and liquid phases. Flocculation is a conventional method used in foodprocessing and wastewater treatments in which dewaterability is achieved by applying suitable chemical flocculants. Osmosis is a conventional method used for food preservation. In this method the so-called humectants (usually sugar or salt) are used for dehydration purposes. When the humectants are applied, the water content is released from food material due to osmosis, which also prevents microbial growth inside the food and enhances its taste. Some common types of drying processes are listed next.

4.2 Solar drying Sun drying or solar drying is a very popular and conventional method still effectively used for food waste management. In this process, the food waste is spread over a surface and the moisture is removed by solar heat energy [21]. This simple method enables processing of huge quantities of a broad range of food wastes such as vegetables, fruits, meats, and nuts in a shorter period with lower energy. However, an inability to control the dehydration level, intensive use of labor, and the need for large areas for spreading the materials are limiting factors [21].

4.3 Tunnel drying In tunnel drying, the food waste is spread over layers of trays arranged in trolleys that are allowed to roam inside a drying tunnel in which hot air is being blown for a specific period of time. The tunnel-drying method is suitable for drying bulk amounts of food waste on an industrial scale. The tunnel-drying method is shown in Fig. 1.

4 Food Waste to Animal Feed—Processing Methods

311

Air out Heater

Fan

Air in

Trolley in

Trolley out

FIG. 1 Drying of food waste by the tunnel-drying method.

4.4 Spray drying The spray drying method is suitable for slurry and liquid food wastes such as milk and juices. In this method the food material is sprayed by an automated nozzle into a hollow chamber as a fine foam; simultaneously hot air is applied to the foam, which removes the water content from the food and makes a fine powder. A typical spray-drying process is presented in Fig. 2.

4.5 Freeze drying Freeze drying is also called lyophilization in which the liquid phase is directly removed from a frozen material under high vacuum. The freeze-drying method ensures the quality of food products, is highly cost effective, and is most suitable for heat-sensitive food material, which also secures microbial food spoilage. Despite the advantages, this method is unsuitable for large-scale animal feed production practices. Peristatic pump

Spraying nozzle

Fan

Sample container

Sample

Drying chamber Heater Bag filter

Dust Main powder fraction

FIG. 2 Drying of food waste by the spray-drying method.

Outlet air flow

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Conversion of Food Waste to Animal Feeds

4.6 Microwave drying Microwaves are a class of electromagnetic waves having the frequency range of 300 MHz to 300 GHz and wavelengths of 1 mm to 1 m. In this technique, the electromagnetic energy of microwaves is converted to thermal energy due to interaction with water molecules present in the food material. The microwave dehydration method is very rapid and advanced, but very expensive compared with other conventional methods.

4.7 Vacuum drying This method works under the principle of decreasing the evaporation point of water below atmospheric pressure. At normal atmospheric pressure, water boils at 120°C but this point lowers to 60°C at a pressure of
20 kPa. Hence, drying under vacuum and lower temperature ensures the quality of feed and preserves the heat-sensitive nutrients [21].

4.8 Silage Silage is a fermented animal feed product produced from various agricultural and industrial food wastes. For the production of silage, food and agriculture wastes are collected in large hollow vessels called silos. The feedstock is fermented under anaerobic conditions for around 1 week; during this period carbohydrates are converted to organic acids by microbial activities. Several types of silage have been prepared since ancient times using rice straw, wheat straw, molasses, fish, etc. The whole plant corn silage has been predominantly used for forage in dairy cattle diets worldwide [22]. Fish silage is produced by either acidification or alkalization of fish waste either after hydrolysis or without hydrolysis. In the silage process during fermentation, the microbes convert organic matter such as cellulose and starch into essential volatile fatty acids, which increase the palatability of the fodder. In addition, during silage the bacteria produce several vitamins that are essential for livestock meal. The silage making ensures long time storage of fodder and ensures the availability of animal feed similar to that of conversion of milk lactose into lactate by Lactobacilli which preserves the milk for long time.

4.9 Liquid feeding Liquid feeding is also a conventional method that has been practiced for a very long time. Recent technological developments have enabled a liquid-feeding method, which is more convenient than other feeding practices. Worldwide, the liquid-feeding method has been successfully implemented by several large-scale swine husbandries. There have been several studies conducted that revealed higher growth rate in pigs fed with liquid-feeding practices than conventional dry meal feeding [23–28]. Another advantage of liquid feeding over the dry-feeding method is the reduction of food wastage. Production cost is much lower than the dry-feeding method, while wastes like skim milk, brewery waste, silage, and other wastes can be readily ground into fine liquid and directly fed to animals. From an engineering point of view, liquid feeding avoids the

5 Direct Conversion

313

FIG. 3 Liquid-feeding system.

double distribution pathway (one for liquid and another for solid) of feeding and the feed can be distributed in controlled quantities. It is thought that waste management and hygiene practices are very much easier in liquid-feeding-enabled husbandries [29]. It has also been reported that the main factors influencing the design of a liquid-feeding system include: • Capacity of the feeding system—defined as the amount of material to be moved, prepared, and distributed at each feeding operation. • Feeding frequency/rate of the food supply—rate of feed to be delivered and number of feeds per day. • Preparation of liquid feed to improve digestibility and palatability. • Conveying—requirements for distribution of feed from the site of preparation to the site of consuming. The disadvantages of the liquid-feeding system are the need for more water for both preparation of food and maintenance, and the generation of effluent is also high. Most importantly, the proliferation of pathogenic diseases is easier than in a solid-feeding system. Fig. 3 shows a typical liquid-feeding system in the pig industry.

5 DIRECT CONVERSION Direct conversion is a simple and effective method successfully used at various levels, which requires minimal preprocessing procedures such as grinding, chopping, and sieving. Conventionally, cabbage and other vegetable wastes are applied as a feed for rabbits. In India, vegetable kitchen wastes are directly used to feed household cows. Habitually in India, boiled rice water, spoiled rice,

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Conversion of Food Waste to Animal Feeds

and other liquid food wastes are collected in separate pots and directly given as an energy drink for cattle. Similarly, the broken grains derived from rice mills are directly fed to poultry. The sago pith, which contains 62% of starch in its total dry weight, is one of the important waste products of the sago industry and is found in abundance in the Salem region of Tamil Nadu state, India. It is estimated that each tonne of sago starch production produces an equal amount of sago pith waste [18]. Hence, the raw sago pith waste acts as a common feed for cattle in these local regions. Malaysian statistics states that around 52,000 tonnes of sago pith waste is being dumped annually into river bodies without proper utilization [30]. Conversion of sago waste into animal feed can abate the environmental impact. However, direct conversion methods have several empirical problems too. To achieve effective integrated and sustainable waste management, both the source of waste generation and animal husbandries should be proximate. Such an integrated approach ensures continuous feeding of husbandries and low distribution expenditure. Since all the food items are susceptible to denaturation within a shorter duration it must be either distributed rapidly or processed to increase its longevity. Also, the direct conversion method is related to several health concerns in feedstock. A report indicated that the feeding of direct unprocessed food waste to pigs has caused a loss of £8 billion to the UK economy [31]. As a result, the direct conversion of food waste to animal feed was totally banned across the European Union [32].

6 INDIRECT CONVERSION The indirect conversion approach involves either simple or complex processing practices of raw food waste. Some food wastes and their suitable simple processing methods for animal feed production are given in Table 3. TABLE 3 Types of Processing Methods for Various Food Wastes and Their Suitable Animal Feed. Type of Food Waste

Processing Method

Feed for Animal

References

Fresh banana foliage

Ensiling with wheat straw (75:25)

Cows and other lactating animals

[11]

Ripe banana peal

Drying and composition with normal diet


20% composition for growing pigs and
30% composition for rabbits

[11]

Citrus pulp

Drying and composition with rice or wheat straw

Lactating cows

[11]

Mango peel

Drying and composition with wheat or rice straw

Broilers

[11]

Grape stalks

Single cell production

Ruminants

[33]

Cafeteria food waste

Composition with corn, soybean meal, and additional diets

Pigs

[34]

6 Indirect Conversion

315

Among the indirect food waste conversion methods, single cell protein (SCP) production is a significant method for animal feed production. The food waste derived from the agricultural and food industries contains microorganisms like yeasts, bacteria, and algae that can effectively utilize food wastes such as substrates to grow rapidly and produce huge quantities of protein-rich biomass. Among other microorganisms, yeast is the most considered organism for SCP production due to its large cell size, low pathogenic nature, and easy processing methods. Generally, SCP production is more suitable for animals than humans due to the higher amount of purine and pyrimidine contents, which are poorly digestible in humans. The yeast is thought to be a suitable feed for pigs due to beneficial effects like promotion of growth, stimulation of the immune system, and increased nutrient uptake [35]. A typical SCP production procedure may involve the following processes. Initially, the food waste to be used as substrate is collected and preprocessed. The preprocessing may involve a series of steps like removal of undesired wastes, grinding, and quality monitoring. Then, the substrate and other additional necessary ingredients such as minerals and stabilizers are added and the pH is adjusted to the appropriate level to favor growth and biomass. The culture medium is sterilized to destroy other microorganisms to avoid interruption, which is necessary so that the expected quality of the SCP meal can be achieved. This culture medium is inoculated with desired microbial inoculum and grown in a reaction vessel under controlled physical and chemical conditions for a certain period, while the inoculum multiplies rapidly by taking up the substrate and producing the biomass. The biomass is harvested through centrifugation, dried to pellets, and packed. During each step the monitoring of microbial contamination and toxicity is essential. Thus SCP production can act as a promising method for food waste conversion to animal feed. Developing suitable techniques to increase the biomass level can greatly contribute to animal feed. However, SCP production can produce a hypersensitivity reaction and may have lower digestibility in some animals, which are considered to be major drawbacks. Although insects contain high levels of protein they cannot be directly fed to humans due to cultural and psychological susceptibility. However, accumulation of higher protein and fats in food animals through insect feed is highly feasible. However, all insect species cannot be used for feed production from waste due the vector and pest effects. A group of five insects, namely common house fly (Musca domestica), black soldier fly (H. illucens), mealworm (Tenebrio molitor), locust (Locusta migratoria, Schistocerca gregaria, Oxya sp., etc.), and silkworm (Bombyx mori, etc.), have been identified for conversion of food waste to animal feed. The black soldier fly larva contains 42.1%  1.0% of protein in its total dry weight [36]. The larva of the house fly, called a maggot, was reported to have 50.4%  5.3% protein and 5.7%  2.4% fiber in its total dry weight, while its pupa contains 70.8%  5.3% protein and 15.7% crude fiber. In addition, both maggot and pupa contain a remarkable quantity of fatty acids [37]. A study estimated that 1 kg of waste biomass can produce 2 kg of insect biomass [38]. It is believed that

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Conversion of Food Waste to Animal Feeds

insect biomass can fulfill the demand for feed in the swine, poultry, and aquaculture production sectors. A black soldier larvae meal has been found to be a suitable ingredient for growing pigs due to the higher value of amino acids and lipids. Chickens fed with dried black soldier larvae gained weight at a rate of 96% when compared with being fed by soybean meal [39–41]. Similarly, the black soldier larvae feed has been extensively studied as a feed for several fish varieties such as channel catfish, blue tilapia, Atlantic salmon, and turbot in which blue tilapia showed remarkable weight gain [39, 42]. However, there are no remarkable studies available that describe feeding ruminants with insect meals. The larvae are collected from the compost in two major ways. In the flotation method the manure along with pupae and larvae is mixed in water and floating larvae and pupae are collected by sieving. In another method the manure is spread over a net (3 mm) over a basin. When larvae try to escape they fall into the basin through the net. The collected larvae are killed in hot water, dried, and ground for making animal feed.

7 FOOD WASTE TO ANIMAL FEED—TYPES Various types of food wastes are used as feed ingredients for a variety of domestic animals. Conversion and processing of food wastes not only prevent putrefaction of wastes, but also help to preserve and transform the wasted food materials into economically useful products [13]. Table 4 provides some of the food wastes and their use as animal feed for different types of animals.

TABLE 4 Different Types of Food Wastes/By-Products and Their Uses as Feed for Different Animals. S. No.

Type of Food Waste

1

2

3

Significance as Feed

Animals That Feed On It

Potato waste

Has energy value similar to corn and barley Nutrient availability: Crude protein 7.6% Ether extract 7.0% Crude fiber 4%

Excellent energy source for feed for cattle Inclusion: 10%–20% as feed pellets

Citrus by-products: citrus peel, pulp, rag, seeds

Nutrient availability: Crude fat 1.2%–2.2% Crude fiber 5.7%–8.6% Crude protein 2.2%–4.2% Total sugar 10.2%–16.5% Nitrogen-free extract 65%–75%

Inclusion: mature cows 10 kg/day Main energy source for beef and other cattle up to 45%

Tomato waste

Total digestible nutrients 55% Crude protein 15%

Inclusion: up to 50% for adult cows and 16% for milch cows and poultry

7 Food Waste to Animal Feed—Types

317

TABLE 4 Different Types of Food Wastes/By-Products and Their Uses as Feed for Different Animals—cont’d S. No.

Type of Food Waste

4

Significance as Feed

Animals That Feed On It

Banana root bulbs

Good source of carbohydrate Total digestible nutrients 50% Crude protein 12%

After cleaning, 20–25 kg/day can be fed to adult cattle

5

Tea waste

Total digestible nutrients 58% Crude protein 17.94% Tannic acid 1.9%

Inclusion: 10%–15% mixed with palatable ingredient and fed to cattle

6

Jackfruit waste

Crude protein 7.9% Crude fiber 14.1% Calcium 0.8% Phosphorus 0.1%

Inclusion: rich source of energy for cattle

7

Tapioca waste

Total digestible nutrients 60%–65% Crude protein 8%–12%

Inclusion: 30% of tapioca waste can be used as feed for adult cows; this helps to maintain body weight of cattle

8

Apple waste

Total digestible nutrients 60% Crude protein 12%

Inclusion: after slicing, grinding, and drying, 30% of this waste can replace 100% maize in the diet of poultry and cattle Quite a palatable diet

9

Mango seed kernel

Total digestible nutrients 55% Protein 6%

Inclusion: 10% for milch cattle, 20%– 40% for growing calves and buffaloes, 50% for ruminants, and also as fish feed

10

Tamarind seed powder

Total digestible nutrients 64% Crude protein 12%

Inclusion: good source of energy for cattle and bullocks

11

Coffee husk

Crude protein 7%–8% Calcium 0.51% Phosphorus 0.25%

Inclusion: for cattle

12

Rice husk

Crude protein 2.9%–3.6% Ether extract 0.8%–1.2% Crude fiber 39%–42%

Inclusion: for cows, horses, and buffaloes

13

Coconut meal

Total digestible nutrients 70%–75% Crude fiber 10% Crude protein 25%–30%

Inclusion: very useful protein supplement in the diet of dairy cows and it increases milk fat content

14

Groundnut meal

Total digestible nutrients 75%–85% Protein 40%–50% High fiber content

Inclusion: feed for cattle, buffaloes, sheep, goats, and pigs

15

Soybean meal

Total digestible nutrients 75%–84% Crude protein 45%–55% Rich in calcium and phosphorus

Inclusion: excellent feed for livestock and cattle

Continued

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Conversion of Food Waste to Animal Feeds

TABLE 4 Different Types of Food Wastes/By-Products and Their Uses as Feed for Different Animals—cont’d S. No.

Type of Food Waste

16

Significance as Feed

Animals That Feed On It

Oil cakes

Good source of vitamin B and protein

Inclusion: feed for cows, goats, and horses

17

Carrot waste

Total digestible nutrients 75%–80% Protein 10%–15% High in vitamin A

Inclusion: 20 kg/day for cattle

18

Citrus molasses

Total digestible nutrients 65%–75% Crude protein 10%–14% Sugar content 41%–43%

Inclusion: 5%–10% in the diet of broilers in poultry and also feed for ruminants

19

Beet molasses

Total digestible nutrients 65%–75% Crude protein 6%–10%

Inclusion: cows and buffaloes

20

Barley by-products

Total digestible nutrients 65% Protein 27%–30%

Inclusion: 30%–40% for dairy cows

21

Rice bran deoiled

Total digestible nutrients 55%–65% Crude protein 13%–16% Good source of protein, carbohydrate, vitamins, and minerals High phosphorus content 1.3%

Inclusion: as feed for cattle, pigs, and ruminants

22

Wheat bran

Total digestible nutrients 65%–70% Crude protein 13%–16% High phosphorus content

Inclusion: feed for cows, goats, and pigs

7.1 Cattle feed Banana peel can be incorporated at levels of 15%–30% in the diet of lactating cows and dairy cattle without affecting palatability and milk yield. Dried citrus pulp is used as a cereal substitute due to its high net energy value (1.66  1.76 Mcal/kg dry matter) for lactating dairy cows [11]. Pineapple juice waste can replace the diets of ruminants completely as well as up to 50% of the total diet of dairy cattle. Cull potatoes are a rich source of starch (60%70%) and up to 15  20 kg/day and 6 kg in the raw form can be fed to lactating dairy cows and breeding cattle, respectively. About 50–55 kg/day of sarson saag waste can be given to an adult cow and is highly palatable [11]. Sundried tomato pomace is a good source of lycopene and can completely replace the conventional feed of cows and adult buffaloes. About 35% of tomato waste

7 Food Waste to Animal Feed—Types

319

can be given to lactating animals without any adverse effect on milk yield. Lactating cows fed with legume by-products and wheat bran gave a yield of 5 L of milk per day [11]. Beef cattle exhibited a growth rate of 600–700 g/day when fed with 90% waste material and a 10% concentrate mixture of pineapple wastes containing peel, pomace, and leaves [43]. Soy hulls were used as animal feed specifically for dairy cows. Husks and pods of common pulses are a good source of digestible protein, which can be used as cattle feed. Citrus pulp contains 6.0% of crude protein and 85% of soluble sugars, one-third of which can be given as animal feed mixture to buffaloes. Pineapple waste together with maize grain, wheat bran, and molasses can be given as feed to draught animals as a source of energy [43]. Wheat bran is a major component in formulating feed for dairy animals, which contains about 10% digestible crude protein, 65% total digestible nutrients, 0.07% calcium, and 0.35% phosphorus. This can be fed to sick animals as it produces a laxative effect in the intestine. Wheat middlings are more digestible than bran and contain 10%–14% crude protein and 9.5% crude fiber. Rice husks contain 8%–11% water, 15.6%–22.6% ash, 14.5–17.5% acidinsoluble ash, 2.9%–3.6% crude protein, 39%–42% crude fiber, and 25–29% nitrogen-free extract (36). Feeding of rice bran alone may result in colic pain; hence, rice bran should always be mixed with other components. Rice bran contains 7% digestible crude protein, 65% total digestible nutrients, 0.06% Ca, and 1.12% P, is rich in vitamin B-complex, and can be used for feeding cattle, buffaloes, sheep, and goats. Rice bran is a major feed in tropical countries and has high oil content (13%). Rice polish contains about 3% fiber, 12% fat, 12%–14% crude protein, and vitamin B-complex. Maize gluten feed is a rich source of protein (45%–48%) and is used in livestock feeding. Sugarcane tops are palatable and cattle can be maintained entirely on them with a little supplement of concentrate mixture or leguminous feeds. Prolonged use of carrots in the diet of dairy cows increases the carotene content of milk and produces yellow-colored milk fat, but does not affect milk yield or milk fat and protein contents. Peas can be included up to 25% on a dry basis in concentrates for lactating cows [14]. Dried citrus pulp can be used as feed up to 50% in the diet of gestating and lactating cows. Fresh baby corn husk containing 11.7% crude protein is more acceptable and palatable compared with conventional maize fodder. Fresh or ensiled baby corn fodder and conventional maize fodder are used as feed for ruminants [11]. In sheep, the dry matter intake of baby corn husk can be given as 2.7% of body weight in dry form, but dry matter intake decreased to 1.6% and 1.2% of body weight when feed is in fresh and ensiled forms. Jackfruit waste and seeds can also be used for feeding small ruminants [14]. Sundried ground pomace can be added up to 50% in the feed of ruminants without affecting nutrient utilization or the health of animals [11]. Fresh cauliflower and cabbage leaves with stems can be fed either as such after drying or in addition with cereal straws. These are a rich source of proteins, soluble sugars, macro- and microelements and have good digestibility. Pea vines and pea straw

320

Conversion of Food Waste to Animal Feeds

have high protein content, low fiber, and higher nutritive value than cereal straws. The empty pea pods are rich in crude protein (19.8%), soluble sugars, phenolics, and macro- and microelements. The empty pea pods are relished by ruminants, and can be fed exclusively. Cull snow peas are an excellent source of protein and can be fed as freshly or after drying to ruminants [11]. Brewery waste is generally used as animal feed due to its high protein content and fiber and it is an ingredients rich feed for ruminants. Citrus fruit wastes such as fresh citrus pulp, citrus silage, dried citrus pulp, citrus meal, citrus molasses, and citrus peel have been used as alternative feeds for ruminants in different growth stages. Bagasse, a dry pulpy residue left after the extraction of juice from sugarcane, is a good source of cellulose, lignin (16%), but with less protein (1.3%), and is good feed roughage for ruminants. Cabbage wastes are fed to ruminants either freshly as meal (cabbage waste dried and ground) or as silage (after wilting) [43]

7.2 Fish feed Fish feed is the most expensive product in aquaculture husbandry. Feed cost can be reduced by replacing the diet with by-products of soybean hull, barley, corn, wheat, etc. [44]. Production of freshwater fishes such as carp and rohu can be carried out by utilizing the wastes from mango-processing industries. The production of fish feed by utilizing food wastes like groundnut cake, palm kernel cake, wheat bran, rice bran, maize bran, livestock blood, and fish wastes like bones, heads, and gut is one of the most profitable ways of fish feed production. Food waste fish feed formulation consists mainly of fruit wastes like peels with some flesh of fruits, namely pineapple, watermelon, cantaloupe, strawberry, banana, and apple, and vegetable wastes such as lettuce, spinach, etc. Cereals like rice bran, soy bean meal, rice grain, and spaghetti are given as fish feed. Meat waste containing 60%–70% of beef, pork, and chicken, and 30%–40% of fish such as salmon, have been used to prepare the fish feed [45]. Carrots have been used as a source of natural pigments with variable results. The cichlid fish (Cichlasoma severum) fed with a diet containing carrots provides 50 mg/kg of total pigments, which results in coloration of the fish. Enhanced pigmentation was observed in freshwater prawns fed with 10% frozen carrot tops. Organic wastes such as brewer’s waste, palm kernel cake, and groundnut cake are used to make fish supplementary feeds. Garlic peel has been reported to possess an immunostimulant property in aquaculture and tends to prevent diseases in the African catfish Clarias gariepinus [2]. It also provided increased resistance to Aeromonas hydrophila infection [46].

7.3 Pet feed Sundried tomato pomace is a good source of lycopene, which can be incorporated up to 20%30% in the diet of rabbits [11]. Cabbage wastes are a potential feed for rabbit, and rabbits fed with water spinach, leaves of cauliflower, cabbage, or Chinese cabbage (Brassica chinensis) exhibited increased growth rates.

7 Food Waste to Animal Feed—Types

321

Rabbits fed exclusively with oats and fresh forage (alfalfa, clover, or cabbage) had good growth. Paddy rice, and to a lesser extent sweet potato roots supplemented with a basal diet of water spinach, improved growth rate and feed conversion efficiency in animals [43].

7.4 Poultry feed Dried citrus pulp can be fed up to 5%–10% in poultry diets and the citrus pulp ensiled with wheat or rice straw in a ratio of 70:30 produces excellent silage [11]. Tannins and cyanide in mango seed kernels can be removed by soaking or boiling in water and then the kernels can be given up to 5%–10% in the diet of broilers. Mango peels are highly palatable and can be fed fresh or along with wheat or rice straw due to their high sugar content (13.2%). Cooked potatoes can be fed up to 40% to poultry chickens. Sundried tomato pomace should be added up to 5%–10% in broiler diets [11]. Bakery by-products can be used as an alternative energy source to replace the high cost of maize, a major ingredient in poultry production. Bakery waste is a palatable, high-energy feed produced from wheat flour, skimmed milk powder, vegetable fat, flavor materials, sugar, and salt. Bakery waste is mostly composed of cake leftovers, pieces of toast, biscuits, or nonmarketed products that have exceeded the expiration date, besides the wastes due to breaking and excess or lack of cooking during processing. Bakery waste can be used as a good replacement for maize and other cereal grains in feeding broilers since it has no antinutritional factor [11]. Cabbage waste is a good source of protein and can also be used for feeding poultry. Cabbage waste was fed either as green at 20%–30%, as meal at 30%–50%, or as silage at 30%–50% in diets from day-old white Leghorn chicks to 50 weeks of age. Body weight increases at a higher rate at 20 weeks with increased egg production when cabbage is given in a poultry diet [43]. Cull carrots are highly palatable and readily consumed by cattle. Carrots are a rich source of total digestible nutrients and can be given up to 20–25 kg/day to young bulls and dairy cows [14]. Carrots can provide carotenoids to laying hens and the diet of laying hens containing 4%–8% of dried carrot meal had improved egg yolk color, egg production, and feed conversion. Purple carrots were beneficial for egg-laying rate and egg and yolk mass production [43].

7.5 Duck feed Different foods like cracked corn, wheat, barley, or similar grains, oats, rice, milo seed, birdseed, frozen peas or corn, earthworms, mealworms, chopped lettuce or other greens or salad mixes, vegetable trimmings or peels (chopped into small pieces) can be given as feed to ducks [14].

7.6 Swine feed Dried ripe banana peels can be fed to growing pigs up to 20% and to rabbits up to 30% of the diet [11]. Pigs are mainly fed with kitchen wastes, including leftover

322

Conversion of Food Waste to Animal Feeds

foods and vegetable peels along with other available crops and crop by-products. The waste from sea food processing can be fermented and used as high-quality feed for pigs, fish, and poultry. The wastes of vegetables and fruits from markets can be directly fed to pigs. Wastes from slaughterhouses can be cooked and given to pigs as feed. Swine feed food wastes like bakery by-products, barley bran, wheat bran, and broiler poultry litter are used more commonly as swine feed. Bakery by-products, barley bran, and wheat bran are used as energy sources and as water absorbents. Broiler poultry litter contains readily available N and minerals as a supplement in animal diets [13]. Soy hulls and wheat flour ground corn are used as feed for pigs [12]. Most feed intake research with pigs fed food waste has been done with pigs in the range of 50250 lb. Food waste-fed pigs are often fed to a finishing weight of 400 lb or greater. Estimates of intake range from about 8–10 lb (as-fed) per pig per day for pigs under 100 to 20 lb or greater for 250-lb pigs. In India, domesticated pig production mostly depends on raw agricultural and kitchen wastes for the fulfillment of pig diets, while the cost of feeding accounts for 80% of pork production expenditure worldwide [47] (Table 4).

8 CONCLUSIONS AND PERSPECTIVES Large quantities and types of food waste are generated worldwide every year. As food waste contains high amounts of nutrients, unsafely disposed of and poorly managed food wastes cause various environmental effects, including greenhouse gas emission, eutrophication, and acidification of the environment. To mitigate the environmental impact, proper conversion of food waste to valuable animal feed is a sustainable option. Although the feeding of food wastes to domesticated animals is a common practice in many parts of the world, scientifically approved production processes and certified quality of feed production are necessary for the healthy production of livestock. Various methods have been developed for the safe conversion of food waste to different livestock feeds in dry as well as wet forms. Food waste-derived animal feed not only replaces commercial feed but also reduces livestock production costs. Conversion of food waste to animal feed can also enhance the circular economy and support the achievement of sustainable development. However, the extensive characterization of various kinds of food wastes before and after conversion into feed is essential for certification and quality control.

REFERENCES [1] FAO, Global Food Losses and Food Waste—Extent, Causes and Prevention, Rome, Italy. http://www.fao.org/3/a-i2697e.pdf, 2011. [2] America’s Food Waste Problem, United States Environmental Protection Agency, https://www.epa.gov/sciencematters/americas-food-waste-problem, 2016. [3] Z. Dou, J.D. Toth, M.L. Westendorf, Food waste for livestock feeding: feasibility, safety, and sustainability implications, Global Food Secur. 17 (2018) 154–161. [4] C. Jinno, Y. He, D. Morash, E. McNamara, S. Zicari, A. King, Y. Liu, Enzymatic digestion turns food waste into feed for growing pigs, Anim. Feed Sci. Technol. 242 (2018) 48–58.

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[5] T.H. Kwan, D. Pleissner, K.Y. Lau, J. Venus, A. Pommeret, C.S.K. Lin, Technoeconomic analysis of a food waste valorization process via microalgae cultivation and co-production of plasticizer, lactic acid and animal feed from algal biomass and food waste, Bioresour. Technol. 198 (2015) 292–299. [6] FAO, Food Wastage Footprint. Impacts on Natural Resources, Rome, Italy. http://www. fao.org/3/i3347e/i3347e.pdf, 2013. [7] J. Gustavsson, C. Cederberg, U. Sonesson, V.R. Otterdijk, A. Meybeck, Global Food Losses and Food Waste, FAO, Rome, 2011, pp. 1–38. [8] J.C. Buzby, H.F. Wells, J. Hyman, The Estimated Amount, Value, and Calories of Postharvest Food Losses at the Retail and Consumer Levels in the United States. EIB121, U.S. Department of Agriculture, Economic Research Service, 2014. http://www.ers. usda.gov/publications/eib-economic-information-bulletin/eib121.aspx. [9] A.Y.Z. Zhang, Z. Sun, C.C.J. Leung, W. Han, K.Y. Lau, M. Li, C.S.K. Lin, Valorisation of bakery waste for succinic acid production, Green Chem. 15 (2013) 690–695. [10] S. Khalid, A. Naseer, M. Shahid, G.M. Shah, M.I. Ullah, A. Waqar, T. Abbas, M. Imran, F. Rehman, Assessment of nutritional loss with food waste and factors governing this waste at household level in Pakistan, J. Clean. Prod. 206 (2019) 1015–1024. [11] M. Wadhwa, M.P.S. Bakshi, Utilization of fruit and vegetable wastes as livestock feed and as substrates for generation of other value-added products, Rap Publ. 4 (2013). [12] R.O. Myer, J.H. Brendemuhl, D.D. Johnson, Evaluation of dehydrated restaurant food waste products as feedstuffs for finishing pigs, J. Anim. Sci. 77 (1999) 685–692. [13] S.Y. Yang, K.S. Ji, Y.H. Baik, W.S. Kwak, T.A. McCaskey, Lactic acid fermentation of food waste for swine feed, Bioresour. Technol. 97 (2006) 1858–1864. [14] M.P.S. Bakshi, M. Wadhwa, H.P. Makkar, Waste to worth: vegetable wastes as animal feed, CAB Rev. 11 (2016) 1–26. [15] L. Chaoyang, Z. Zhang, X. Ge, Y. Wang, X. Zhou, X. You, H. Liu, Q. Zhang, Biohydrogen production from apple waste by photosynthetic bacteria HAU-M1, Int. J. Hydrogen Energy 41 (2016) 13399–13407. [16] S. Jaya, H. Das, A vacuum drying model for mango pulp, Dry. Technol. 21 (7) (2003) 1215–1234. [17] K. Cahyari, R.A. Putra, Design of biogas plant from fruit market waste in Indonesia, in: Renewable Energy Conference, Berlin, 2010. [18] J.C. Lai, W.A.W.A. Rahman, W.Y. Toh, Characterisation of sago pith waste and its composites, Ind. Crop. Prod. 45 (2013) 319–326. [19] I.S. Arvanitoyannis, A. Kassaveti, Fish industry waste: treatments, environmental impacts, current and potential uses, Int. J. Food Sci. Technol. 43 (2008) 726–745. [20] J.S. Cohen, T.C.S. Yang, Progress in food dehydration, Trends Food Sci. Technol. 6 (1995) 20–25. [21] D.S. Jayas, Academic Training. Food Dehydration. Reference Module in Food Sciences, Elsevier, 2019, pp. 1–10. [22] L.F. Ferraretto, R.D. Shaver, B.D. Luck, Silage review: recent advances and future technologies for whole-plant and fractionated corn silage harvesting, J. Dairy Sci. 101 (2018) 3937–3951. [23] R.S. Barber, R. Braude, K.G. Mitchell, Further studies on the water requirements of the growing pig, Anim. Sci. 5 (1963) 277–282. [24] D.E. Becker, A.H. Jensen, B.G. Harmon, H.W. Norton, B.C. Breidenstein, Effect of restricted diet on the performance of finishing pigs, J. Anim. Sci. 22 (1963) 1116. [25] W.L. Roller, H.S. Teague, A.P. Grifo Jr., V.R. Cahill, Paste feed for pigs, J. Anim. Sci. Cambr. 24 (1965) 857. [26] R. Braude, J.G. Rowell, Comparison of dry and wet feeding of growing pigs, J. Agric. Sci. 68 (1967) 325–330. [27] W.A. Kneale, Comparison of commercial wet and dry feeding systems for fattening bacon pigs, Exp. Husband. (1972). [28] K. Scholz, O. Siegl, Investigations on the use of pumpable feed in pig fattening in comparison to dry machine feeding, German Agric. 9 (1958) 492.

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[29] T.R. Cumby, Design requirements of liquid feeding systems for pigs: a review, J. Agric. Eng. Res. 34 (1986) 153–172. [30] A.M.D. Mohd, M.N. Islam, B.M. Noor, Enzymic extraction of native starch from sago (Metroxylonsagu) waste residue, Starch-St€arke 53 (12) (2001) 639–643. [31] UK House of Commons Report, The 2001 Outbreak of Foot and Mouth Disease. Report by the Comptroller and Auditor General (No. HC 939), London, UK. https://www.nao. org.uk/wp-content/uploads/2002/06/0102939.pdf, 2002. [32] European Commission. Regulation (EC) No 1774/2002 of the European Parliament and of the Council of 3 October 2002 Laying Down Health Rules Concerning Animal By-Products not Intended for Human Consumption. Brussels, Belgium, Official Journal of the European Communities. https://eur-lex.europa.eu/LexUriServ/LexUriServ.do? uri¼CONSLEG:2002R1774:20070724:EN: (2002) [33] L. Nicolini, C. Volpe, A. Pezzotti, A. Carilli, Changes in in-vitro digestibility of orange peels and distillery grape stalks after solid-state fermentation by higher fungi, Bioresour. Technol. 45 (1993) 17–20. [34] M.L. Westendorf, Z.C. Dong, P.A. Schoknecht, Recycled cafeteria food waste as a feed for swine: nutrient content digestibility, growth, and meat quality, J. Anim. Sci. 76 (1998) 2976–2983. [35] T. Gervasi, V. Pellizzeri, G. Calabrese, G.D. Bella, N. Cicero, G. Dugo, Production of single cell protein (SCP) from food and agricultural waste by using Saccharomyces cerevisiae, Nat. Prod. Res. 32 (2018) 648–653. [36] A. Gutierrez, R.A.V. Ruiz, H.M. Velez, Compositional, microbiological and protein digestibility analysis of larval meal of Hermetiaillucens (Diptera:Stratiomyidae) at Angelopolis-Antioquia, Colombia. Rev. Facult. Nacl. Agron. Med. 57 (2004) 2491–2499. [37] U. Okah, E.B. Onwujiariri, Performance of finisher broiler chickens fed maggot meal as a replacement for fish meal, J. Agric. Technol. 8 (2012) 471–477. [38] A. Collavo, R.H. Glew, Y.S. Huang, L.T. Chuang, R. Bosse, M.G. Paoletti, House cricket small-scale farming, in: M.G. Paoletti (Ed.), Ecological Implications of Minilivestock: Potential of Insects, Rodents, Frogs and Snails, Science Publishers, New Hampshire, 2005, pp. 519–544. [39] H.P. Makkar, G. Tran, V. Heuze, P. Ankers, State-of-the-art on use of insects as animal feed, Anim. Feed Sci. Technol. 197 (2014) 1–33. [40] O.M. Hale, Dried Hermetiaillucens larvae (Diptera: Stratiomyidae) as a feed additive for poultry, GaEntomolSoc J (1973). [41] L. Newton, C. Sheppard, D.W. Watson, G. Burtle, R. Dove, Using the black soldier fly, Hermetiaillucens, as a value-added tool for the management of swine manure, in: Report for Mike Williams, Director of the Animal and Poultry Waste Management Center, North Carolina State University, 2005. [42] K. Bondari, D.C. Sheppard, Soldier fly, Hermetiaillucens L., larvae as feed for channel catfish, Ictaluruspunctatus (Rafinesque), and blue tilapia, Oreochromisaureus (Steindachner), Aquacult. Res. 18 (1987) 209–220. [43] C.M. Ajila, S.K. Brar, M. Verma, R.D. Tyagi, S. Godbout, J.R. Valero, Bio-processing of agro-byproducts to animal feed, Crit. Rev. Biotechnol. 32 (2012) 382–400. [44] C. Marlowe, A. Caipang, J. Mabuhay-Omar, M.M. Gonzales-Plasus, Plant and fruit waste products as phytogenic feed additives in aquaculture, AACL Bioflux 12 (1) (2019) 261–268. [45] Z. Cheng, Use of food waste feeds for culturing low trophic level fish (grass carp, bighead carp and mud carp): persistent toxic substances, Open Access Theses and Dissertations 76 (2014). https://repository.hkbu.edu.hk/etd_oa/76. [46] K. Thanikachalam, M. Kasi, X. Rathinam, Effect of garlic peel on growth, hematological parameters and disease resistance against Aeromonashydrophila in African catfish Clarias gariepinus (Bloch) fingerlings, Asian Pac. J. Trop. Med. (2010) 614–618. [47] R.P. Saikia, Chemical composition of kitchen waste for pig feeding, Int. J. Sci. Environ. Technol. 6 (2017) 3489–3495.

Chapter | Twelve

Pyrolysis and Gasification of Food Waste Jun Zhoua, Gaihong Wanga, Mengyao Wanga, Peiru Zhua, Binghua Yanb, Liwen Luoc,d, and Jonathan Wongc,d Bioenergy Research Institute, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Chinaa College of Resources and Environment, Hunan Agricultural University, Changsha, Chinab Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinac Sino-Forest Applied Research Centre for Pearl River Delta Environment, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, Chinad

1 INTRODUCTION Food waste is generated by public canteen, family, and catering industry daily and mainly includes waste during meal processing and food residue after meal [1, 2]. The generation of food waste is estimated to rapidly increase from 2.78 billion tons to 4.16 billion tons in Asian region by 2025 [3]. Particularly in China the growth rate of food waste has increased by more than 10% with the development of industry and the increase of population. Approximately, 60–70 million tons food waste would be produced in China every year, which account for nearly 50% of total domestic waste production [4]. About 3337 metric tons (36%) of municipal solid waste is food waste in Hong Kong, accounting the largest category of municipal solid waste disposed at landfills. The current practice of dumping these organic wastes at landfills does not meet the principle of sustainable development and has a negative impact on the environment. This food waste not only takes up valuable landfill space but also decomposes and produces odor, leachate, and greenhouse gases. The food waste production yield in European countries is 88 million tons [5]. In India, more than 60 million tons of food waste is produced every year [6]. The production yield of food waste in Japan is reported to be 17 million tons [7]. The production of food waste reaches 30 million tons in the United States [8]. The amount of food waste 325 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00012-9 Copyright © 2021 Elsevier Inc. All rights reserved.

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discharged increases given the continuous growth of the global population and the improvement of people’s living standards. Large amounts of food waste cause serious pollution, and their disposal remains challenging. Utilization of biomass-rich food waste will not only help the environment but also increase the utilization of renewable resources by human beings, in line with the development direction of sustainable development and circular economy. The disposal of food waste has always been one of the more difficult problems in solid waste treatment. Food waste is rich in organic matter, such as fat, protein, and starch; has high water content; and is highly perishable [2, 9]. According to the reports in literature, the carbon-nitrogen ratio of food waste is approximately (10–30):1, and the content of carbon is the highest (approximately 30%–45%) [10, 11]. Methods for treatment of food waste mainly include landfill, aerobic composting anaerobic digestion, incineration, pyrolysis, and gasification [4, 10–12]. Food waste is conducive for pyrolysis and gasification due to its high organic content and calorific value. Recycling energy in biomass by high-temperature pyrolysis has become the research direction of energy utilization of solid waste in recent years [13]. This technology converts organic matter into energy-based flammable gas, pyrolysis oil, and versatile pyrolytic carbon under temperature-driven conditions to achieve cleanliness and recycling [13–16]. Biomass pyrolysis and gasification is affected by many factors, such as reactor type, heating rate, and material properties. From our literature search (Fig. 1), it has been found that literatures fit into the keywords of “food waste” and “pyrolysis and gasification” from the database of “Web of Science” have gradually increased in recent years. Thus food waste pyrolysis and gasification is progressively taking attention throughout the world with the consideration to circular economy of biowaste. In this chapter, principles of pyrolysis and gasification technology; the characteristics of various pyrolysis and gasification reactors; and the parameters

Publication (numbers)

350 300 250 200 150 100 50 0 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

FIG. 1 Journal publications on food waste and pyrolysis and gasification in the last 10 years.

2 Principles of Pyrolysis and Gasification

327

such as moisture content, temperature, and copyrolysis are discussed. The properties and functions of gas, liquid, and biochar products obtained by pyrolysis and gasification are also summarized. Finally the main problems and some perspectives for the engineering application of food waste pyrolysis and gasification are provided.

2 PRINCIPLES OF PYROLYSIS AND GASIFICATION Pyrolysis and gasification of food wastes or other biomass has attracted extensive attention in recent years. In general, pyrolysis and gasification represents a process of thermal degradation of waste under anaerobic or anoxic conditions that produce recyclable products such as biochar, oil, and combustible gases. Among them a reaction in which the excess air coefficient is zero is generally referred to as pyrolysis, and a reaction in which partial oxidation and thermal decomposition are performed under an oxygen deficiency condition is referred to as gasification. Pyrolysis and gasification has been used to produce charcoal from biomass for thousands of years. In the actual process, pyrolysis and gasification often exist in the reaction process at the same time. Food waste and other biomass pyrolysis and gasification generally consist of three stages: The first stage is called dehydration stage (the temperature is generally below 125°C, mainly reflecting the evaporation of water in biomass); the second stage is activation pyrolysis (the temperature is 125–500°C, mainly reflecting the process of pyrolysis conversion of biomass); and the third stage is slow pyrolysis (the temperature is up to 500°C, mainly reflecting the temperature range and heating rate of different pyrolysis reaction stages of biomass during slow and continuous gasification change process) [14–16]. Biomass pyrolysis and gasification is a complex process; the main reaction processes are shown in the following equations [17–19]: Food waste or other biomass + Air=O2 =H2 O ! Char + Tar + Ash + Gases ðCO, H2 , CO2 , CH4 , light hydrocarbonsÞ

(1)

Partial oxidation : 2C + O2 ¼ 2CO

(2)

Complete oxidation : C + O2 ¼ CO2

(3)

Hydrogasification reaction : C + 2H2 ¼ CH4

(4)

Water  gas shift reaction : CO + H2 O ¼ CO2 + H2

(5)

Steam reforming reaction : CH4 + H2 O ¼ CO2 + H2

(6)

Water  gas reaction : C + H2 O ¼ CO + H2

(7)

Boudouard reaction : C + CO2 $ 2CO

(8)

328

Pyrolysis and Gasification of Food Waste

3 PYROLYSIS AND GASIFICATION REACTORS Reactors are the core equipment in the food waste pyrolysis and gasification system. According to the operation mode of the equipment, reactors can be divided into fixed bed, fluidized bed, rotary kiln, and other types of reactors [20–22]. The greatest advantage of the fixed bed reactor is that it is simple to manufacture, low in cost, small in moving parts, and simple in operation, but the cavity is easily formed in the furnace, and the material-handling amount is small. Typical fixed bed reactors are classified into a down suction type and a top suction type. The downdraft pyrolysis gasifier is suitable for materials with low water content. The outstanding advantage of the downdraft pyrolysis gasifier is that the generated gas passes through the high-temperature zone; therefore the tar content in the produced gas is low [23]. The produced gas of the top suction pyrolysis gasifier does not pass through the high-temperature zone, and the tar content is high. However, the materials are dried by the hot air flowing upward and can be used with high water content (water content up to 50%). Fluidized bed gasification is the pyrolysis and gasification of food waste in the fluidized state. The temperature field of the entire reactor is hooked, the heat transfer and mass transfer rate are fast, and the reactor structure is easy to enlarge and suitable for food waste and biomass waste. The large-scale gasification of materials is an important research direction of current gasification technology [24]. Fluidized bed gasification technology has good applicability to food waste with concentrated emissions and large scale. The rotary kiln reactor is divided into external and internal heat types according to the heating method, which has strong adaptability to materials; is suitable for solid, liquid, and gas waste of various sizes and shapes; and has the advantages of convenient control and simple operation. The disadvantage is that the pyrolysis reaction is insufficient, and the gas leakage is easy to occur at the outlet of the rotary kiln [25, 26]. On the basis of the fixed bed and fluidized bed reactor, some improved reactors, such as rotating bed and multistage circulating fluidized bed, are formed for the shortcomings in the process [27]. Many commercial food waste and biomass pyrolysis and gasification projects have been developed and invested in the past few decades [20, 25, 28]. Fig. 2 shows a two-stage fixed bed gasification technology (Thermoselect) developed by Vivera Corporation Ltd., which uses periodic continuous feed, and the municipal solid waste can be hydraulically compressed to one-fifth of the original volume without breaking [20]. Subsequently the materials are pushed to the indirect heating channel for pyrolysis, the temperature is about 600°C, the pyrolysis products enter the 800°C high-temperature reactor for common gasification, and the temperatures of the top and bottom of the high-temperature reactor are 1200°C and 2000°C, respectively. After being cooled, decontaminated, and dried, the gasification gas can be used in engines, steam turbines, and steam boilers, as well as in chemical raw materials, while some gases are used for heating channels. Fig. 3 shows the rotary kiln

3 Pyrolysis and Gasification Reactors

329

FIG. 2 Schematic of the Thermoselect process. Adapted from T. Malkow, Novel and innovative pyrolysis and gasification technologies for energy efficient and environmentally sound MSW disposal, Waste Manage. 24 (2004) 53–79, with permission from Elsevier. Input material

Gasifier Ai Arshes

Drier Revolving drum

Oxygen Char

Pyrolysis

Gas engines

Gas storage

Cooling system

Gas cleaning

water

cleangas

Gas scrubbing

Activated Hydrogen sulphide fiter carton fiter

Scrubbing water treatment Scrubbing water

FIG. 3 Schematic of the PKA technology. Adapted from T. Malkow, Novel and innovative pyrolysis and gasification technologies for energy efficient and environmentally sound MSW disposal, Waste Manage. 24 (2004) 53–79, with permission from Elsevier.

technology developed in Germany, which uses high-temperature pyrolysis and gasification technology. Before starting the material needs to be pretreated first and then pyrolyzed in an externally heated rotary kiln at a temperature of 500–550°C for 45–60 min. The pyrolysis gas enters the converter, and the hydrocarbons and organic volatiles are cracked at 1000°C. A homogeneous

330

Pyrolysis and Gasification of Food Waste

Cooler Cyclone

Combustion reactor

Steam

Steam

Upper GR

ILS

Separator

Cyclone

Cooler

FG PG Sample point

Lower GR

Air 3

Steam

Steam

Air 2 CR fuel Air 1

LLS

GR fuel

FIG. 4 Advanced design of the 100 kWth DFB steam gasification pilot plant. Adapted from F. Benedikt, J.C. Schmid, J. Fuchs, A.M. Mauerhofer, S. M€uller, H. Hofbauer, Fuel flexible gasification with an advanced 100 kW dual fluidized bed steam gasification pilot plant, Energy 164 (2018) 329–343, with permission from Elsevier.

gas rich in CO and H2 is produced [20]. Fig. 4 shows the 100-kW dual-fluidized bed steam gasification technology in Austria [29]. The fluidized bed gasifiers have the characteristics of load and fuel flexibility, suitable resources of gasification medium, well distribution of high temperature throughout the gasifier, high heat transfer rates, and high cold gas efficiency [30]. These gasifiers will be influenced by produced dust particles and tar because of the different feedstock, which lower the quality of fuel gas and lead to the malfunctioning of equipment at the same time [29, 30].

4 Factors Affecting the Pyrolysis and Gasification of Food Waste

331

4 FACTORS AFFECTING THE PYROLYSIS AND GASIFICATION OF FOOD WASTE Pyrolysis and gasification technology is a thermochemical method to produce energy from the biomass. Operational and thermochemical factors (Table 1) that affect the pyrolysis and gasification of food waste include moisture content, temperature, substrate composition, particle size, heating rate, and residence time. Most of the influential factors are clearly addressed in the publications, so in this section, crucial factors for the pyrolysis and gasification of food waste were selected (moisture content, temperature, and copyrolysis of food waste).

4.1 Effect of Moisture Content on the Pyrolysis and Gasification of Food Waste The moisture content of food waste has a significant effect on pyrolysis and gasification efficiencies, product composition, and overall energy balance of the food waste and other biomass gasification [31]. The drier the food waste is, the higher gasification efficiency will be, which might increase the hydrogen concentration consisted in the gas outlet. The gasifier temperature and the endothermic reactions will be reduced, because part of the available heat in the reactor is proceeded to evaporate the water from raw material. Doherty et al. [32] determined that the low calorific value of gasification gas and the conversion efficiency of gasification energy decrease significantly with the increase in moisture content of raw materials (Fig. 5). The gas heating value and cold gas efficiency decreased in the whole moisture range (5%–30%) in Fig. 5 [32].

TABLE 1 Factors Influencing Pyrolysis and Gasification of Food Waste. Factors

Effect

References

Moisture content

Moisture content significantly affects pyrolysis and gasification efficiencies, product composition, and overall energy balance of the food waste and other biomass gasification

[31–33]

Temperature

The heating value and producer composition are affected by the temperature during the pyrolysis and gasification process

[13, 34–37]

Copyrolysis of food waste

Food waste can be mixed with plastic, straw, and other biomass together to pyrolysis and gasification according to a certain ratio, and the interaction among materials can be used to improve product quality and reduce energy consumption

[38–41]

Particle size

Particles size can affect the heat transfer rate during the pyrolysis and gasification process

[42]

Heating rate

Heating rate has an important role on the composition of the final product

[42]

Residence time

The composition of liquid, gaseous, and biochar product all can be affected by the residence time

[42]

332

Pyrolysis and Gasification of Food Waste

FIG. 5 Effect of biomass moisture content on product gas composition, gas higher heating value on a mass basis, and cold gas efficiency on a higher heating value basis. Adapted from W. Doherty, A. Reynolds, D. Kennedy, The effect of air preheating in a biomass CFB gasifier using ASPEN Plus simulation, Biomass Bioenergy 33 (2009) 1158–1167, with permission from Elsevier.

The characteristics of biochar were also influenced by the moisture content of the biomass during the pyrolysis and gasification process. Table 2 shows the effect of moisture content on the characteristics of biochar under different temperatures. From the element distribution in cattle manure char (Table 2), there was no obvious trend on the elemental contents of cattle manure char produced on 350°C. It can be explained by the incomplete pyrolysis because of high moisture content of raw material (85.12%) and insufficient pyrolysis temperature (350°C). However, the carbon content was decreased with increasing moisture content at other temperatures. For example, Xin et al. [33] run pyrolysis temperature at 450°C; the remaining carbon content in manure char was decreased from 46.86% to 42.43% when moisture content of raw material increased from 10.13% to 85.12%. Meanwhile the carbon content in manure char increased with increased temperature. While even with increasing moisture content, no significant variation was observed on the H and O contents of manure chars at the same temperature. From all measured cattle manure chars, the N content decreased with increased moisture content and temperature; the S component in biochar was not affected by the pyrolysis temperature and moisture [33]. The carbon content in the food waste char was obviously higher than that in the manure char, and this may be due to the higher carbon content in the food waste [33, 43]. Feedstock containing approximately 15 wt% moisture content is suitable for biomass gasification [31, 44]. This process can be achieved by cogasification or food waste pretreatment techniques. Cogasification is identified as a thermochemical process, in which food waste and another second carbonaceous

4 Factors Affecting the Pyrolysis and Gasification of Food Waste

333

TABLE 2 Effect of Moisture Content on the Characteristics of Biochar Under Different Temperatures [33, 43]. Conditions

Elemental Composition (wt%)

Samples

T (°C)

M (%)

C

H

O

N

S

Cattle manure

–

–

42.38

5.9

28.69

2.51

0.45

Manure char

350

10.13

45.96

3.37

18.99

3.26

0.80

Manure char

350

56.20

46.11

3.34

19.54

3.20

0.58

Manure char

350

85.12

45.85

4.79

25.41

2.84

1.33

Manure char

450

10.13

46.86

2.58

13.79

2.90

0.69

Manure char

450

56.20

46.34

2.46

13.57

2.65

0.54

Manure char

450

85.12

42.43

2.60

14.93

2.14

1.08

Manure char

550

10.13

49.33

1.86

10.47

2.43

0.46

Manure char

550

56.20

48.21

1.89

5.79

2.25

1.71

Manure char

550

85.12

45.82

1.77

8.99

1.79

0.78

Manure char

650

10.13

49.81

1.37

6.03

1.54

0.51

Manure char

650

56.20

47.42

1.28

8.50

1.39

0.96

Manure char

650

85.12

45.90

2.25

2.31

1.13

0.67

Food waste

–

–

46.10

5.70

40.79

1.74

0.17

Food waste char

500

0

71.30

2.10

6.44

2.64

0.12

material can be simultaneously gasified [45, 46]. Herein a basic biomass feedstock of high moisture content mixed with this drying/demoisturizing second material is the common pretreatment method. Drying can be classified according to the location such as on-site and off-site; also, it can be categorized as active and passive dryers. Based on the types of applied dryer, active dryers such as boilers and dryer burners use flue gas, steam, and waste thermal energy to dry food waste; passive dryers, on the contrary, use natural energy sources such as solar and wind energy for drying [47, 48].

4.2 Effect of Temperature on the Pyrolysis and Gasification of Food Waste Temperature is an essential operating parameter for the pyrolysis and gasification process of food waste since it affects the heating value and the composition of production according to the thermodynamics of the reactions involved [13, 34]. Wu et al. [35] found that the relationship between bed temperature and the heating value of the produced syngas presented negative liner. In addition, carbon conversion and steam cracking can be effectively promoted

334

Pyrolysis and Gasification of Food Waste

FIG. 6 Analysis of the gaseous products. Adapted from B. Grycova´, I. Koutnı´k, A. Pryszcz, Pyrolysis process for the treatment of food waste, Bioresour. Technol. 218 (2016) 1203–1207, with permission from Elsevier.

by high bed temperatures so as to minimize the formation of char and tar. Samples of pyrolysis gas are taken at temperatures of 480–530°C, 550–600°C, 650–700°C, and 750–800°C with respect to the thermogravimetric analysis (Fig. 6) by Grycova´ et al. [36]. The increase in temperature accelerates hydrogen evolution. The highest hydrogen concentration (WaCe 61 vol.% and WaPC 66 vol.%) was measured in the last gas sample at the temperature of 750–800°C. The concentrations of hydrocarbons and carbon monoxide decrease with increasing temperature [36]. Moghadam et al. [37] reported the cogasification of biomass and polyethylene was affected by temperature. Furthermore, high temperature helped syngas production, improved hydrogen production, and reduced hydrocarbons and CO2 content. Opatokun et al. [49] evaluated the potential utilization of biochars that were produced from the food waste digestate at four different pyrolysis temperatures (300°C, 400°C, 500°C, and 700°C). It reported that the biochar production yield decreased with increased pyrolysis temperature and the highest yield of biochar was 60.55% under the condition of lowest temperature (300°C) [49]. In general, besides carbon conversion and gas production, the yields of H2 and CO increase with increasing temperatures. By contrast, if the yields of CO2 and hydrocarbons decrease, syngas quality and gasification efficiency will be highly upgraded.

4.3 Copyrolysis of Food Waste With Different Types of Materials The composition of food waste is complicated, and it varies greatly with changes in region and season. The difference in living standards in different places also leads to the change in food waste components. Different components may interact during typical pyrolysis, which affects the tar formation characteristics. In most cases, certain interaction effects occur with mixed pyrolysis of

5 Products of the Food Waste Pyrolysis and Gasification Processes

335

various food waste components [38]. Zhou et al. [38] conducted an experimental study on the interaction among nine representative household waste components by thermogravimetric experiments. Orange peel and rice, as well as rice and poplar, interacted during the common pyrolysis process. Significant interactions reduce the peak value of the curve and delayed the peak time. Hosoya et al. [39] found an interaction among the three major components of biomass (cellulose, hemicellulose, and lignin). Lignin significantly inhibited the formation of macromolecular products during the thermal cracking of cellulose and promoted the production of small molecules. The formation of cellulose inhibited the formation of coke in the lignin thermal cracking product and promoted € the conversion of lignin into phenolic compounds. Onal et al. [40] studied the interaction between potato skin and low-density polyethylene in a pyrolysis process using a fixed bed reactor. The addition of low-density polyethylene increased the specific gravity of olefins in the liquid product, the C and H contents increased, and the O content decreased. The calorific value was high, and the interaction increased the yield and quality of the pyrolysis oil. Yang et al. [41] found that the interaction between organic food waste and plastic accelerated the copyrolysis efficiency in the fixed bed experiments, and this interaction helps to reduce the tar yield by 2%–69% and increase the char yield by 13%–39% when compared with linear calculation. Moreover, heavy components increased more than two to six times, and less nitrogen-containing components decreased around 61%–93% in the formation of tar derived from mixtures [41]. Therefore, for food waste with high water content, it can be mixed with plastic, straw, and other biomass together to pyrolysis and gasification according to a certain ratio, and the interaction among materials can be used to improve product quality and reduce energy consumption [41].

5 PRODUCTS OF THE FOOD WASTE PYROLYSIS AND GASIFICATION PROCESSES: GAS, LIQUID, AND SOLID COMPONENTS Pyrolysis and gasification are recognized as sustainable approaches that have increasing economic profits, less environmental concerns, and enhanced carbon sequestration. Gas, liquid, and solid products are obtained during the food waste pyrolysis and gasification processes.

5.1 Biooil Pyrolytic oils generated from food waste and other biomasses included acids, sugars, alcohols, ketones, aldehydes, phenols and their derivatives, furans, and other mixed oxygenates [50, 51]. Phenolic compounds are always exited at high concentrations even up to 50 wt%, which can be consisted of phenol, eugenol, cresols, xylenols, and large amount of alkylated (poly-)phenols [50]. The heating value of pyrolytic oil from food waste and another biomass is approximately 15–20 MJ/kg. Compared with thermal degradation of single biomass, less aqueous phase, lower char yield, and more oil were produced by copyrolysis. The pyrolysis tar generated from biomass is reddish brown with

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irritable odor, but the oil produced from copyrolysis is yellow with usual petroleum hydrocarbon odor. Copyrolysis of food waste or biomass with synthetic polymers could generally be an environmental friendly approach for the transformation of waste into valuable fuels [52].

5.2 Biochar Pyrolytic biochar was produced during the pyrolysis process of food waste and other biomass feedstock. This biochar is generally produced by a carbon-rich matrix containing almost all inorganic components. In addition to the advantages of strong adsorption capacity, stable chemical properties, and strong regenerative capacity of carbon materials, biochar has a welldeveloped pore structure, high specific surface area, stable aromatic structure, and abundant surface functional groups. The physicochemical properties of biochar and its yield are related to the feedstock characteristics and thermochemical conditions. Temperature is one of the most important parameters that will affect the characteristics and yield of biochar [53–55]. When the pyrolytic temperature is higher than 300°C, the cross section of produced biochar presents graphene structure [56]. It is noteworthy that graphene is a flat, polyaromatic, and monolayer structure of carbon possessing a high stability, resistance, and electrical conductivity [56]. All of the testing parameters, such as the biochar production yield, nutrient contents, cation exchange capacity, available phosphate, and the extractable cations, are decreased with increasing temperature, while their alkalinity and aromatization levels are increased with the increase of temperature [57]. The pH value, heating value, and specific surface area are positively correlated to the pyrolysis temperature [58]. On the perspective of carbon sequestration, a higher temperature is preferred for biochar production [59]. Al-Wabel et al. [60] operated the pyrolysis of conocarpus wastes ranging from 200°C to 800°C and reported that all of the parameters of the electrical conductivity, basic functional groups, ash content, carbon stability, and total nutrient contents (i.e., C, N, P, K, Ca, and Mg) increased with the increase of temperature; however, other parameters, such as the yield of biochar; total content of elements O, H, and S; unstable organic carbon content; and acid functional groups, decreased with the rising temperature [61] (Fig. 7). The main three compositions of biomass are cellulose, hemicellulose, and lignin. According to the results from previous studies, cellulose and hemicellulose are the two responsible composition for the generation of volatile products by pyrolysis, and lignin is mainly represented for the biochar production [62]. Therefore, if feedstock contains higher lignin content, this material will have a chance to produce more biochar. Grycova´ et al. [36] found that the surface area of tested pyrolysis biochars from food wastes was very small (below 10 m2 g1), and this surface area of biochar could be further enlarged by activated steam and other chemical treatments and thus improve its capability for application [36, 63].

5 Products of the Food Waste Pyrolysis and Gasification Processes

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FIG. 7 Van Krevelen diagram for various biochar derived from various feedstocks under different pyrolysis temperatures. Adapted from Z.K. Zhang, Z.Y. Zhu, B.X. Shen, L. Liu, Insights into biochar and hydrochar production and applications: a review, Energy 171 (2019) 581–598, with permission from Elsevier.

Biochar has a wide range of applications in the energy and environmental fields [55, 64, 65] and also applied on the amendment of agricultural soils considering on the soil condition [64]. Biochar can be produced with different properties that are particularly related to the selected pyrolysis time and temperature and feedstock features [64]. The properties of surface functional groups can be affected to form correlated acidic and/or basic sites; the porosity of biochar can be manipulated to form microporous and mesoporous structures. Biochar is also considered an adsorbent for the removal of various pollutants in wastewater, which can be used to adsorb soluble heavy metals, organic contaminants, inorganic nitrogen and phosphorus components, and other contaminants [64]. Considered to the removal of organic contaminants by biochar, related factors including pyrolytic temperature, operated pH, feedstock features, and ratios of pollutant will affect the interactions between biochar organic components and further influence the removal performance [66]. Biochar produced under the condition of low pyrolysis temperature (1 h) and low heating rates (5–7°C/min), whereas fast pyrolysis is generally aimed at producing a liquid product in high yield [48]. To suppress gas production due to secondary cracking, the vapor residence time is controlled and short and rapid cooling is used to maximize the liquid product yield [49]. Thus the higher heating rate and shorter residence time are used in fast pyrolysis. The specific surface area and pore volume of biochar are mainly influenced by thermochemical conditions such as temperature, residence time, and heating rate. You et al. [50] reported the exponential function correlation between the specific surface area and the total carbon content, where the reported specific surface area ranged from 14.3 to 748.5 m2/g and the carbon content was in the range from 21.8 to 89.9 wt%. 2.4.2 GASIFICATION In a gasification process, gaseous products (H2, CO, CO2, N2, etc.), liquid products (tar and oil), and solid products (char and ash) are formed. Because gasification is aimed at producing gaseous products, the yield of biochar is only approximately 5%–10% of the raw biomass material mass, which is lower than that of fast pyrolysis (15%–20%) [51]. The mechanism of gasification can be divided into several steps, i.e., drying ! pyrolysis ! oxidation/combustion ! gasification, but each step cannot be separated from the others in terms of temperature and pressure.

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2 Different Types of High-Value Products Recoverable from Food Waste

The parameters affecting the gasification reactions include reaction temperature, gasification agent type, gasification agent-biomass ratio, and pressure. Generally, temperature is considered as the most important among the parameters directly affecting gasification reactions. Carbon conversion rate and the composition and heating value of the product gas also vary according to the gasification agent used in the gasification process. Kajitani et al. [52] investigated the effects of gasification agents on the characteristics of char using a reducing gasification agent (H2O) and oxidizing gasification agents (CO2 and O2). The ratio of the small and large aromatic ring structure of the aromatic compounds composing the char was lower and the contents of alkaline metals, such as Mg and Ca, in the char were higher when H2O was used. In general, gasification biochar had smaller specific surface areas and total pore volumes than those from slow and fast pyrolysis, which is mainly caused by the effects of ash melting (pore clogging), pore expansion and collapse, and tar deposition corresponding to the high temperatures during combustion and/or reduction stages of gasification [53].

2.4.3 HYDROTHERMAL CARBONIZATION The HTC process occurs in the subcritical region as shown in Fig. 3. It is widely known that the characteristics of water change dramatically under subcritical conditions. Temperature increases below 374°C decrease the dielectric constant, weakening water’s hydrogen bonds and producing high ionization constants, which enhance the dissociation of water into acidic hydronium ions (H3O+) and basic hydroxide ions (OH) [54]. Furthermore, the subcritical water itself can boast a sufficiently higher H+ concentration as compared to liquid water, which is an excellent medium for the acid-catalyzed reaction of organic Pyrolysis and gasification

Biomass/waste Heat

Product distribution ratio, %

Pyrolysis unit T> 300°C

Gas

Liquid

Biochar

Slow pyrolysis

35

30

35

Fast pyrolysis

20

70

10

Gasification

85

5

10

(A)

Biomass/waste Heat

HTC processes T 100~350°C ΔP

Bio-oil

Pc = 221

Gas

P/bar

Hydrothermal carbonization Solid

Superficial

Liquid

Subcritical region

HTC Critical point

Sterilization/Hydrolysis

Hydrochar Vapor

(B)

Tc = 374

T/°C

FIG. 3 Comparison of the product distributions of pyrolysis and gasification of biomass.

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Emerging Technologies for the Treatment of Food Waste

compounds without added acid. Depending on the temperature under saturated pressure, biochar, bio-oil, and gaseous products (CO, CO2, CH4, H2, etc.) are the main products of a hydrothermal process below 250°C, at 250–400°C, and above 400°C, respectively [55, 56]. It is apparent that the HTC process is not restricted to traditional lignocellulosic biomass; feedstocks can be more complex, such as FW [57, 58], MSW [59], animal manure [60, 61], sewage sludge (SS) [62, 63], and aquaculture and algal residues [64]. Generally, the yield of hydrochar produced from the HTC process was higher than pyrolysis, and a higher C content of hydrochar was found compared to the char produced from dry processes [47]. It is reported that cellulose and hemicellulose were favored for developing a microsphere structure, meanwhile cellulose/hemicellulose and lignin are correlated to diverse oxygenous groups and benzene ring structures, respectively [65]. To improve the yield of char, recirculation of the aqueous phase was found to increase the energetic recovery efficiency and the mass yield of hydrochars from sweet potato waste [66]. Furthermore, FW was also blended with woody biomass as the substrate for HTC [67]. The hydrochar pellets from high-ratio FW had decreased ignition temperature and maximum weight loss rate with a wider temperature range, indicating increased flammability and moderate combustion. A summary of biochar yield from FW is presented in Table 1. These findings demonstrate that the HTC of the FW woody biomass blend was suitable for pelletization for solid biofuel production.

TABLE 1 Biochar Production From Food Waste (FW) Via the Hydrothermal Carbonization Process. Substrate Types

Process Conditions

Yield of Hydrochar (%)

References

FW

180–260°C, 60 min

35–53.8

[68]

FW

225–275°C, 4–96 h

57.8–69.5

[58]

FW blended with woody biomass

180–260°C

38.5–81.3

[67]

Orange peel waste

240°C, 2 h

40–56

[65]

Sweet potato waste

220°C, 60 min

60.3–66.3

[66]

Corncob residues

190–370°C

33–66

[69]

Coconut fiber

250°C, 30 min

65.7

[70]

Grape pomace

175–275°C, 10–60 min

66–73.9

[71]

2 Different Types of High-Value Products Recoverable from Food Waste

355

2.5 Microwave-Assisted Thermochemical Conversion Recent studies have focused on the green conversion of FW using unconventional heating systems such as microwave irradiation [72]. Microwave is absorbed by polar molecules in a reaction matrix to generate heat, which is considered to be a volumetric and selective dielectric heating with a lower energy demand [72, 73]. The efficient energy transfer process results in less masstransport limitation than other heating processes, which reduces the reaction time and increases the product yield and purity as compared to the conventional heating process. According to the differences of reaction time, temperature, and microwave power, microwave-assisted FW treatment can be divided into three categories. 1. Microwave-assisted extraction of molecules For the by-products of various fruit peels produced during food processing, there are many kinds of bioactive compounds such as essential oil, polyphenols, pectin, betalain, and carotenoids in fruit peels. If the compounds in peels are recovered effectively, the peels may be a potential source of these natural bioactive compounds for food, cosmetic, and medicinal uses. Microwaveassisted extraction at relatively low temperatures and low power can be a promising low-cost and facile synthesis method to extract high-value products from FW. 2. Microwave-assisted catalyzation for biodiesel production For the by-products of waste oil produced during the cooking process, refining biodiesel is an environmentally friendly way to deal with waste oil treatment. Biodiesel (fatty acid alkyl ester) is a promising alternative to fossil fuel in terms of engine performance and plentiful availability as it is derived from renewable sources. Microwave-assisted catalyzation can significantly reduce the reaction time and lower the cost [73, 74]. 3. Microwave-assisted pyrolysis For the by-products of a complex component, which is difficult to separate and degrade, microwave-assisted pyrolysis is a last resort. Microwaveassisted pyrolysis is a fast-growing and widely used technique to process lignocellulosic biomass feedstocks such as corn cob and stover, rice/wheat straw, coconut/palm kernel shell, and other agricultural and forestry crops or residues, etc. [75–80]. This technology offers several advantages over conventional pyrolysis techniques because it provides instantaneous and uniform heating of raw materials, high heating efficiency, and can use different feedstocks (e.g., minimal raw material pretreatment requirements). Microwave-assisted pyrolysis has the potential to be an emerging technology for producing bio-oil, biochar, and gas from FW. Microwave-assisted thermochemical conversion can be classified into three types according to the classification of final products, i.e., microwave-assisted extraction of molecules, microwave-assisted catalyzation for biodiesel production, and microwave-assisted pyrolysis (Table 2).

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Emerging Technologies for the Treatment of Food Waste

TABLE 2 Microwave-Assisted Thermochemical Conversion of Food Waste (FW) to High-Value Products.

Material 1. Microwave- Canola seed cake assisted extraction of molecules

Source

Microwave Power and Reaction Time

Oil 633 W (5 min), extraction L:S ratio 6:1 processing by-product

Product

References

Total phenolics and flavonoids

[74]

Orange peels

Citrus 500 W (15 min), Essential oil, processing without solvents polyphenols, and by-product pectin

[81]

Citrus lemon peels

Citrus 1200 W (15 min), Essential oil processing L:S ratio 9:1 by-product

[82]

Palm pulp and endocarp, nut shell

Food 170°C (2 min)– Hydroxymethylfurfural/ [83] processing 140°C (30 min) furfural by-product

Brewer’s spent grains

Brewing 200 W by-product (2.5–7.5 min), 70–90°C

Carboxymethyl cellulose

[75]

Pumpkin biomass Food 1200 W (10 min), Pectin industry 102.2°C, L:S by-product ratio 50:1

[76]

Dragon fruit peels Fruit 100 W (8 min), processing 35°C by-product

[77]

Betalain

Jackfruit peel

Fruit 500 W (29 min), Pectin processing 86°C, L:S ratio by-product 48:1

[78]

Gac peel

Fruit 120–360 W Carotenoids processing (4–30 min), by-product 25% additional organic loading), the nitrogen backload increased significantly and management strategies were needed to be implemented. Thus adequate evaluation of all environmental benefits is the most critical precursor to further facilitate full-scale applications of codigestion and to resolve the remaining bottlenecks. More importantly, resolving these bottlenecks is not a challenge solely linked to wastewater or waste services. Indeed, it requires concerted efforts from several other disciplines and all stakeholders involved.

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367

4.2 Food Waste as External C Source to Enhance BNR in Wastewater Adding external carbon sources (e.g., VFAs) to wastewater to enhance BNR is well established in practice. Rather than using refined carbon sources such as methanol, locally generated FW has been considered as the carbon supplement to nutrient-rich wastewater.

4.2.1 DIRECT USE OF FOOD WASTE Bolzonella et al. [147] found that the denitrification of leachate from a continuously stirred-tank reactor treating activated sludge by adding FW and nitrate removal were improved from 6 to 17 mg NO–3-N/L. Paolo et al. [148] demonstrated that the uptake of FW macerators improved denitrification efficiency at a local sewage treatment plant. Zhang et al. [149] also demonstrated that FW was a suitable carbon source for BNR by denitrifying 50 g NO–3-N/L to less than 1 mg/L with the addition of filtered liquor of fermented FW. The feasibility of the direct use of FW as an effective carbon source for both N and P removal from black water was also testified by Tannock et al. [150]. The final removal rates of N and P in effluent were up to 89% and 80%, respectively. 4.2.2 USAGE OF VOLATILE FATTY ACIDS DERIVED FROM FOOD WASTE Several studies have shown that FW-derived VFAs perform better than commercial carbon chemicals in terms of removal efficiency and denitrification rate [149, 151]. The removal efficiency of N and P improved from 44% and 37% to 92% and 73%, respectively, when VFA was used as a carbon source [152]. The fermentation liquid of FW consists mainly of acetate, propionate, and butyrate. Studies found that higher denitrification efficiency and faster denitrification rate were evident when commercial sodium acetate was replaced by the mixture of acidogenic liquid (39.26% acetate, 32.14% propionate, 24.52 isobutyrate, and 4.04% isovalerate) [153]. The composition of waste-derived VFA can influence denitrification efficiency and rate. Acetic and propionic acid-fed processes attained the highest nitrate removal rates in denitrifying processes among different VFA types [154]. The feasibility of waste-derived VFAs for enhancing biological nitrogen removal has also been proved to be economically feasible in full-scale plant [155]. It was found that the use of VFA-rich fermented liquid gave similar efficiency as a commercial acetic acid, obtaining removal efficiencies of N and P up to 72% and 90%, respectively.

4.3 Codigestion of Wastewater and Food Waste In scenario 3, the activated sludge process is replaced by anaerobic digestion. The interest here focuses on the greater sustainability of anaerobic rather than aerobic processes: lower sludge production; lower energy consumption since oxygen is not required for organic matter removal; and recovery of energy

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Emerging Technologies for the Treatment of Food Waste

through methane production [129]. One of main bottlenecks in direct sewage digestion is low strength organic loading, which leads to ineffectiveness in the anaerobic digestion process [156]. Thus an appropriate sewage preconcentration step is required to facilitate economical anaerobic digestion with reduced volume and elevated temperatures [157]. Conventionally, the physicochemical pretreatment steps, including precipitation and flotation, were adopted, but high chemical consumption and increased salinity of the effluent were identified as two major bottlenecks. Compared to two typical technologies for sewage preconcentration, i.e., direct sewage microfiltration and continuous aerated sewage microfiltration, a combined coagulation microfiltration system under an optimal aeration strategy showed higher concentration efficiency, slower permeability decline (i.e., better control of membrane fouling), and easier collection of retained organic matter [158]. Among various anaerobic digesters, the anaerobic membrane bioreactor system may represent a sustainable option for the joint process of OFMSW with domestic wastewater because: (1) it increases biogas production since more organic matter enters the system; (2) it reduces fossil fuel consumption related to FW transportation since it can be collected together with the gray water from kitchens; and (3) it avoids environmental issues (contamination of soil, water, and air) that may occur when FW is landfilled [159]. Studies on the codigestion of wastewater and FW are also currently limited [160].

5 CONCLUSIONS AND PERSPECTIVES Although anaerobic digestion might be a good choice for FW treatment, it is also true that anaerobic digestion processes often encounter difficulties such as frequent process failure and long retention time of substrate, as well as the need for posttreatment of digestate liquid and solids. Other alternative options are discussed for the treatment of FW. Based on the concept of cascade utilization, the extraction of high-value molecules from FW is the preferred strategy. Correspondingly, various microwave-assisted extraction methods have been developed to improve extraction efficiency. The most beneficial aspect of biodrying is autonomous heat production from biodegradation of organic matter contained in the wastes. Regarding the nature of wastes, biodegradability and heat contents need to be considered when designing a biodrying process, and thus some pretreatments might be necessary to adjust the moisture content before biodrying. In recent years, transformation to a circular economy has already been seen in the wastewater servicing sector; however, due to the limitation of the characteristics of sewage and sludge, there are defects in the anaerobic digestion performance of these substrates. It is feasible to incorporate FW into the domestic wastewater management framework based on primary lab-scale tests and full-scale operation; nevertheless, it still needs more fundamental studies in this area in terms of material flow under the comanagement framework.

References

369

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[143] P. Sosnowski, A. Klepacz-Smolka, K. Kaczorek, S. Ledakowicz, Kinetic investigations of methane co-fermentation of sewage sludge and organic fraction of municipal solid wastes, Bioresour. Technol. 99 (13) (2008) 5731–5737. [144] V. Cabbai, M. Ballico, E. Aneggi, D. Goi, BMP tests of source selected OFMSW to evaluate anaerobic codigestion with sewage sludge, Waste Manag. 33 (7) (2013) 1626–1632. [145] W. Zhang, S. Wu, J. Guo, J. Zhou, R. Dong, Performance and kinetic evaluation of semi-continuously fed anaerobic digesters treating food waste: role of trace elements, Bioresour. Technol. 178 (2015) 297–305. [146] C. Macintosh, S. Astals, C. Sembera, A. Ertl, J.E. Drewes, P.D. Jensen, K. Koch, Successful strategies for increasing energy self-sufficiency at Gr€ uneck wastewater treatment plant in Germany by food waste co-digestion and improved aeration, Appl. Energy 242 (2019) 797–808. [147] D. Bolzonella, L. Innocenti, P. Pavan, F. Cecchi, Denitrification potential enhancement by addition of anaerobic fermentation products from the organic fraction of municipal solid waste, Water Sci. Technol. 44 (1) (2001) 187–194. [148] B. Paolo, F. Francesco, P. Daniele, B. David, Application of food waste disposers and alternate cycles process in small-decentralized towns: a case study, Water Res. 41 (4) (2007) 893–903. [149] Y. Zhang, X.C. Wang, Z. Cheng, Y. Li, J. Tang, Effect of fermentation liquid from food waste as a carbon source for enhancing denitrification in wastewater treatment, Chemosphere 144 (42) (2016) 689–696. [150] S.J.C. Tannock, W.P. Clarke, The use of food waste as a carbon source for on-site treatment of nutrient-rich blackwater from an office block, Environ. Technol. 37 (18) (2016) 2368–2378. [151] F. Liu, Y. Tian, Y. Ding, Z. Li, The use of fermentation liquid of wastewater primary sedimentation sludge as supplemental carbon source for denitrification based on enhanced anaerobic fermentation, Bioresour. Technol. 219 (2016) 6–13. [152] S.J. Lim, D.W. Choi, W.G. Lee, S. Kwon, H.N. Chang, Volatile fatty acids production from food wastes and its application to biological nutrient removal, Bioprocess Eng. 22 (6) (2000) 543–545. [153] F. Yan, J. Jiang, H. Zhang, N. Liu, Q. Zou, Biological denitrification from mature landfill leachate using a food-waste-derived carbon source, J. Environ. Manag. 214 (2018) 184–191. [154] X. Li, J.E. Swan, G.R. Nair, A.G. Langdon, Preparation of volatile fatty acid (VFA) calcium salts by anaerobic digestion of glucose, Biotechnol. Appl. Biochem. 62 (4) (2015) 476–482. [155] H. Liu, P. Han, H. Liu, G. Zhou, B. Fu, Z. Zheng, Full-scale production of VFAs from sewage sludge by anaerobic alkaline fermentation to improve biological nutrients removal in domestic wastewater, Bioresour. Technol. 260 (2018) 105–114. [156] H. Kjerstadius, S. Haghighatafshar, A. Davidsson, Potential for nutrient recovery and biogas production from blackwater, food waste and greywater in urban source control systems, Environ. Technol. 36 (13) (2015) 1707–1720. [157] W. Verstraete, P.V. de Caveye, V. Diamantis, Maximum use of resources present in domestic used water, Bioresour. Technol. 100 (23) (2009) 5537–5545. [158] Z.Y. Jin, H. Gong, H. Temmink, H.F. Nie, J. Wu, J.E. Zuo, K.J. Wang, Efficient sewage pre-concentration with combined coagulation microfiltration for organic matter recovery, Chem. Eng. J. 292 (2016) 130–138. [159] R. Li, X. Li, Recovery of phosphorus and volatile fatty acids from wastewater and food waste with an iron-flocculation sequencing batch reactor and acidogenic co-fermentation, Bioresour. Technol. 245 (2017) 615–624. [160] J.R.B. Angeli, A. Morales, T. LeFloc’h, A. Lakel, Y. Andres, Anaerobic digestion and integration at urban scale: feedback and comparative case study, Energy Sustain. Soc. 8 (2018).

Chapter | Fourteen

Food Waste Policy Jeff Cooper Former President of the Chartered Institution of Wastes Management and the International Solid Waste Management Association, Independent Environmental Consultant and Technical Writer, London, United Kingdom

1 Introduction This chapter addresses the problem of food waste policy, legislation, and regulatory requirements in a number of countries in different continents, where practices vary quite widely. However, as a UK-based researcher, to report on this issue with a single country’s experience was important because there were many lessons that were learned. This experience has also guided policy and practice both within the European Union and more widely in recent years. Nevertheless, there were some interesting examples and practices from other countries that were adapted in the United Kingdom and that affected the policies adopted toward tackling food waste in specific sectors. There are many varied approaches that have been undertaken to tackle the issue of surplus food and food waste, but in policy terms, it is often the initiatives of committed individuals that make the difference and promote the changes necessary to avoid food waste generation. These examples are referenced in the sections on Italy and Denmark where individuals have had a significant impact in getting the public and then policy makers to address the food waste issue. Overall policy development to tackle food waste has lagged behind the initiatives and actions that have been instituted by committed individuals, charities, and environmental associations, but this is normal practice for the development of any policy issue that needs to be tackled through the actions of the wider civil society. In many countries the targets and goals for food waste reduction that have been set merely reiterate the UN Sustainable Development Goal target 12.3 as a national policy objective, often omitting the intermediate 2025 target altogether and focusing just on the 2030 target. Fortunately for the politicians who have been promoting these objectives, it is very likely that they would be out of office and will therefore not have to account for their countries’ having failed to meet the target. 377 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00014-2 Copyright © 2021 Elsevier Inc. All rights reserved.

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Food waste, most predominantly from unused edible food sources, is an important global environmental issue. Each year, according to the United Nations’ Food and Agriculture Organization, 1.3 billion tonnes per annum (tpa) of food waste is generated globally [1]. The issue of food waste has become increasingly recognized as a global sustainability problem and acknowledged as sufficiently significant to be included by the United Nations as one of their Sustainable Development Goals (SDG 12.3) with a target of 50% reduction in food waste globally by 2030 [2] and an intermediate target of a 20% reduction by 2025. The SDG target 12.3 adopted in September 2015 is specific in its objectives: to halve per capita food waste at the retail and consumer level by 2030, together with reduction of food losses along the food production and supply chain. With food waste reduction, there was the issue of how food waste ought to be measured. In the United Kingdom, there were three categories of food waste designated when detailed analyses were undertaken in 2005–07: edible food, food residues that were inedible, and an intermediate category of food waste that might be edible, such as the peelings from potatoes and carrots and the stems of broccoli. The classification was changed in 2017 so that the last category is now regarded as food waste, giving a clear edible food and inedible food waste distinction. There are different sources of food waste throughout the supply chain from farm to fork, and their significance varies from developing through transition to developed economies in terms of what these sources of food waste are and the options for tackling them [3]. The developing and transition economies generate most of their food waste in the earlier stages of production because of the lack of adequate storage and processing facilities. However, once purchased by consumers, after discards during preparation, this food is then fully consumed, albeit there are exceptions, such as hospitality events, mainly weddings and other major family celebrations. The developed economies have good initial food production processes, albeit there has been criticism that their retailers often have too rigid standards for sizing and presentation for fruit and vegetables, for example. The main concern in developed economies is that too much of the food purchased by consumers and hospitality companies is discarded, on average over 30%, either before use or after preparation and cooking. When all opportunities for preventing surplus food and food waste have been exhausted inevitably, there will be an amount of food waste generated. There are several options available for its recovery and disposal. In rural settings for most food wastes, there is the chance of feeding domesticated animals, such as chickens, other fowl, and pigs with much of it. In urban environments until recently, food waste has generally been discarded together with other residual, nonrecyclable household wastes. The same situation has applied to commercial premises as well. Even much industrial food waste has gone for disposal, although often since these premises are dealing with a limited number of food waste streams, the opportunity to divert such wastes to animal feed uses is

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easier. Thus spent barley from distilleries in Scotland, for example, is often sold or given away to neighboring dairy and beef farmers for their animal feed. In the past in Europe, food waste from catering establishments and even households was collected to be used as pig food (pig swill in the United Kingdom). After a series of animal-feed adulteration scandals in the 1990s, the EU took dramatic action by banning all material that was not from raw material sources from being used as animal feed. Internationally, there is a difference in that on both sides of the Pacific (United States, China, and Korea); pig swill from catering establishments is still acceptable for animal feed. Nevertheless, even in these countries, there is still the need for tight controls to ensure that the food waste materials are fit for purpose [4]. Over time, many countries, regions, and municipal authorities have introduced segregated organic collections of food waste and/or green/yard waste collections from households, albeit often this is just from single-family homes and not from multifamily blocks. The destination for the mixed organic collections was initially to composting plants, sometimes open windrow systems but increasingly because there was increasing concern about animal health risks, so the use of in-vessel composting (IVC) systems has become more common and indeed more frequently used even for green waste processing. Food waste collections are now almost exclusively treated through anaerobic digestion (AD), although technically aerobic processing is also possible. In conformity with the waste hierarchy and the more nuanced food waste hierarchy, preventing the generation of food waste at whatever stage it is being produced, processed, or made available for final consumption is the ideal position for a comprehensive and coherent national food waste policy. Most countries now try to tackle food waste at source through food waste prevention. Food producers, from the farming sector to food processors and food manufacturers, are now looking ever more closely at the opportunities that are available to grow crops that are more marketable and to select and process those crops in increasingly sophisticated ways to maximize marketable food products. After that initial processing, manufacturers preparing food products are examining a wider range of opportunities to minimize their wastes from all aspects of their foodprocessing activities [5]. After maximizing food waste prevention, opportunities utilizing surplus food for onward sale through companies dealing with close to “sell-by” products or for charitable donation are the most favored options. Many companies have established links with specialized food surplus charities to ensure that edible food can be consumed by people in need [6]. Then, there is the potential of using certain surplus food streams as animal feed, albeit with the restrictions noted earlier. After all those opportunities have been utilized, in economic and environmental terms, the best option in the United Kingdom, and as has been increasingly recognized in most other countries, for treating segregated food waste is AD. The other main choice would be IVC, sometimes ideally together with green wastes. Internationally, there is an increasing policy emphasis being placed on AD for use of biomethane for a

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variety of renewable energy uses, including upgrading for gas grid injection and vehicle fuel utilization or for electricity generation and with the solid digestate residue, after further composting treatment, to be used for soil amendment [7]. For the longer-term future, beyond 2030 and ideally well before, there is the need for national governments, hopefully fully supported by citizens, to recognize the link between the climate change emergency and the food waste reduction perspective [8]. For citizens, this might mean a dramatic change in their eating habits to reduce their consumption of meat and dairy products [9]. Unfortunately, in the national food waste reduction policies that have been produced to date, it is seldom that there is reference to even consider the necessity for consumers to limit their intake of the most carbon-intensive foods that they might consume. The climate change link with food waste also needs to be made more explicit in most national policies. This will become an increasingly urgent issue in the context of both global and national state perspectives on food security for a rising global population.

2 European Perspectives European country perspectives on food waste overall conform to the waste hierarchy, as most are EU MSs (member states) and many others are either part of the wider European community through membership of the European Economic Area or they are Accession countries or otherwise waiting to enter the EU. A 2016 estimate of European food waste [10] showed that 70% of food waste arose in the household, food service, and retail sectors, with production and processing sectors accounting for the remaining 30%. European food waste policy and legislation is now one of the main aspects of the Circular Economy Package (CEP) that completed its legislative processes on July 4, 2018, and has a number of requirements that will need to be fulfilled by the EU MSs. The EU CEP replicates the overall requirement of the UN SDG 12.3 target adopted in September 2015, to halve per capita food waste at the retail and consumer level by 2030, together with reduction of food losses along the food production and supply chain but goes further in detailing mechanisms in specific policy areas and in requiring a number of appropriate consequential actions to be adopted by EU MSs. These EU actions include the following: • Developing a common EU methodology to measure food waste, which was agreed in 2019. • Operating a multistakeholder platform to help define measures needed to achieve the food waste SDG target, facilitate intersector cooperation, and share best practice and results achieved. • Taking measures to clarify EU legislation related to waste, food, and feed and facilitate food donation and use of food no longer intended for human consumption in animal feed, without compromising food and feed safety. • Examining ways to improve the use of date marking by actors in the food chain and its understanding by consumers, in particular best before labeling. • Introducing mandatory food waste collections.

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The EU Commission’s policies have also been helpful in encouraging food waste behavioral research, and community initiatives using a range of funding mechanisms and EU institutions to ensure these proposed actions should be realized. Therefore the commission has established a forum dedicated to food waste prevention; the EU Platform on Food Losses and Food Waste (FLW) was set up in 2016 bringing together EU institutions, experts from EU MSs, and relevant stakeholders selected through an open call for applications. The platform aims to support all actors in defining measures needed to prevent food waste, sharing best practice, and evaluating progress made over time. A number of subgroups have been established covering the following topics: • food donation • food waste measurement • action and implementation • date marking and food waste prevention One example of an EU-sponsored project, funded by the EU-LIFE initiative, is TRiFOCAL London—Transforming City FOod hAbits for Life. It was an initiative that ran from 2016 to 2020 led by Resource London—a partnership between the Waste and Resources Action Programme and the London Waste and Recycling Board—together with the charity Groundwork London [11]. These organizations won a bid with the LIFE programme of the European Commission to deliver the €3.2 million initiative in London, which will be a test bed for other European cities, of which there are nine already linked to the project. The project brought together three strands of food policy: food waste prevention, healthy sustainable eating, and recycling food waste. The main focuses for influencing behavioral change through this project were London boroughs to engage residents, community groups because they have extensive and deep local communication networks and linkages, and also large businesses because they often provide staff with meal services and can also otherwise influence their workforces’ eating and food waste behaviors.

2.1 UK Food Waste Policy Development The first UK food waste prevention initiative was started in 2007 with the government-sponsored Waste and Resource Action Programme’s (WRAP) launch of their Love Food Hate Waste campaign. At that time, there was 10 million tpa of food waste being generated each year in the United Kingdom, predominantly from households (70%). Following that initial promotional effort that utilized a wide range of media, there was a decline in the food waste generated by households, a 13% reduction from 2007 to 2013. In one respect the timing of the campaign was opportune because it coincided with the global financial crisis that made everyone more aware of the cost of food they were purchasing and potentially discarding uneaten. The consumer response would therefore also have been reinforced by constraints on consumer budgets to deliver a reduction in many people’s unnecessary food purchases.

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In addition, at the same time, a number of municipalities in the United Kingdom introduced segregated food waste collections for their residents [12]. This reinforced information to those residents that they were purchasing food only to discard it into their food waste caddies (kitchen containers) uneaten. However, more recent unpublished research is ambivalent about the effect of providing segregated food waste collections on the behavior of residents. While some people might have felt they were wasting food unnecessarily, many others would regard their discards as environmentally sound because their food waste would be used for productive purposes, such as production of electricity through AD. Research undertaken by WRAP revealed that food waste generation had increased in 2014 slightly overall, although difficult to assess accurately, given the measurement errors inherent in this evaluation and this trend have continued to 2019. This result is mainly as a result of population increase but perhaps with a per person slight decline compared with the period 2005–07, giving the following estimated outcomes: Households Food product manufacturing Hospitality and food sector Retail sector

7.1 million tonnes (of which 5.0 m had been edible) 1.85 million tonnes 1.0 million tonnes 0.25 million tonnes

The total amount of this wastage in monetary terms was around €23B. Faced with continuing high levels of consumer food wastage, WRAP was forced to change the emphasis of its campaign so that it addressed a wide range of issues that influenced food wastage. These campaigns have included, for example, Chill your Fridge in October 2018 that reached 1.3 million households, because research had revealed that a high proportion of the nation’s fridges were operating at too high a temperature, rather than the ideal 0–4°C. This campaign was supported by 21 businesses and 26 local authorities. The campaign was reintroduced in the autumn of 2019. In 2019 the national food waste policy was changed to become more nuanced to address specific issues and groups with a range of low-budget initiatives to address a variety of food waste issues and nudge citizen behavior toward food waste prevention, including the following: • Eat Me/Freeze Me to encourage people to freeze any food that remained after initial consumption of an item and that might subsequently have been discarded, especially bread. • COMPLEAT—directed mainly to bread products where many of the crusts and for some people, the edges of loaves are discarded and to encourage people to eat all the fruit, such as apple skins, and vegetables, such as carrots and potatoes and broccoli stems without peeling them.

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• A number of social media initiatives were undertaken to address the 18–34-year age group, the main demographic cohort with the highest food waste discards. The initial WRAP Love Food Hate Waste campaign not only focused on consumers but also engaged supermarkets and their suppliers to spread the waste prevention and food reutilization message. The campaign was assisted by an existing voluntary industry program coordinated through WRAP that was initially directed to the minimization of packaging waste for both consumer packaging products and the secondary and transit packaging used by retailers and their suppliers. The success of the Courtauld Commitment, as the packaging initiative was entitled, has latterly been redirected toward tackling food waste. In the food retail sector, there is emphasis on surplus food redistribution to charitable causes and failing that use for animal feed before those foods that cannot be reutilized are sent for recycling by AD processing. In addition, the retail sector was encouraged to help their customers to avoid food waste by, for example, cutting out two for one offers for food products, not giving additional food products when specific items were purchased and through the wider use of resealable packaging to extend products’ shelf life. The supermarket chains were also invited to use the promotional materials WRAP had devised for the Love Food Hate Waste campaign. Several supermarkets also stimulated their consumers’ food waste prevention through their own in-house leaflets and newsletters. The Courtauld Commitment food packaging reduction program was therefore an easy option for extension to food waste prevention, given that the majority of consumer packaging is used for food products. Since 2005 the Courtauld Commitment had gone through several iterations, but in 2015 Courtauld 2025 (C2025) was launched with the aim to reduce UK food and drink waste per head of population by 20% by 2025 compared with 2015 in conformity with the interim UN SDG 12.3 target. C2025 also has ambitious targets for reducing the greenhouse gas emission impacts of food production, processing, and final consumption and in addition limiting the water utilized for food production throughout all of its life cycle stages [13]. However, there was an interesting precursor to the C2025 policy initiative. In 2012 it was recognized that there was one major food sector outside the conventional food supply chain that also needed to be addressed: the whole range of hospitality companies that provide prepared food for customers, from cafes and restaurants, pubs and clubs to hotels, and specialist hospitality venues, such as conference and event facilities and their supply chain. The food waste generated by these venues amounted to 1 million tpa in 2015. There was also the packaging associated with the production and distribution of this food. The Hospitality and Food Service Agreement (HaFSA) was therefore set up under the auspices of WRAP in 2012 as a 3-year program to stimulate the sector to reduce their overall waste and especially their food waste generation. The participating trade organizations, companies, and premises were encouraged to follow the resource management hierarchy to achieve an overall reduction in their

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waste generation to ensure both greater economic and environmental benefits for their businesses. Food waste costs to the UK restaurant sector were around €800 million pa from almost 200,000 tpa of food waste [14]. The total cost of this food waste amounted to €4000 per tonne in 2011, which included food purchases, labor, utility costs, and waste management. Food purchases and labor are more than 90% of the total cost [14]. In the HaFS sector, restaurants have the lowest expenditure on preprepared and frozen food because these establishments mainly cook fresh food to order for customers and therefore most of their food waste came from meal preparation operations. WRAP [14] found that 80% of food waste from restaurants, public houses, and education establishments ended up in residual waste containers and therefore was not treated through AD or IVC, although it was noted that 7% of food waste was disposed to sewer through sink disposal units. The HaFSA was successful in raising the amount of waste that was sent for recycling, in addition to the introduction of some food waste prevention measures. However, while overall 51% of total waste from UK restaurants was recycled, 65% of this was dry wastes, mainly packaging, with only 6%–7% of food waste being sent for recovery. After the HaFSA had come to an end in December 2015, the sector subsequently agreed to continue its efforts on waste prevention, reuse, and recycling under the auspices of the Courtauld Commitment 2025 that brings together several different strands of food waste prevention to rationalize the UK’s efforts to more efficiently produce, process, and redistribute food in the United Kingdom. Specifically the HaFS sector agreed to participate in the industry-wide Food Waste Recycling Action Plan. Specifically, key associations and companies planned to build on the work of HaFSA to increase recycling rates by promoting the case for change and encouraging businesses to reduce food waste, to redistribute surplus food, and to separate their food waste and to reuse and recycle it [15]. In the early stages of the HaFS sector initiative, there was discussion as to the title that should be adopted to engage potential participants. In the end the title, Your Business is Food (YBIF), was adopted and adapted from a similar initiative in South Australia, the Australian State that is at the forefront of food waste initiatives in Australia. As a consequence, there was a developed YBIF 7-day tracking sheet that enabled food businesses to look at their different sources of food waste over a typical week. However, following its promotion among potential restaurants and other businesses preparing food for a range of outlets, WRAP introduced a 3-day version to meet business concern that 7 days was too long to engage staff. It also provided a quick means for assessing their food waste to determine whether they needed to undertake for the full 7-day option. Almost all did utilize the new 3-day option and found that their food waste was costing them not only the collection and disposal costs but also the costs of food purchase and preparation when they used the WRAP calculator to convert food waste generated to determine the overall financial cost.

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There are now a number of additional ways to simplify the process of calculating food waste from restaurants, including Winnow and Leanpath’s services, especially for plate waste, the most difficult element to assess in restaurants. From the work undertaken so far through a number of initiatives generated by C2025 and HaFSA partners and local projects, such as the GLA’s FoodSave scheme [16], there is a considerable body of research findings showing both the costs of food waste and the opportunities available to businesses to prevent and reutilize it. In addition to the HaFS sector program, in June 2017, a C2025 YBIF Manufacturing Focus Group was set up to address the earlier stages of the food supply chain, from companies taking raw ingredients and converting these to a wide range of food products for onward sale to processors, wholesalers and retailers, and the HaFS sector. The trade organizations participating on behalf of their members included the Food and Drink Federation, Federation of Bakers, Dairy UK, British Meat Processors Association, and the Institute of Grocery Distribution (IDG). In 2018 WRAP joined forces with the IDG to launch the Food Waste Reduction Roadmap with its theme of Target, Measure, Act to address food waste occurring in the processing and distribution supply chain. There has also been some work undertaken under the auspices of WRAP with the farming sector, generally linked to supply of materials to their primary customers. This has included assessment and selection of specific types of potatoes, for example, so that the most productive marketable varieties could be identified and grown in future [17]. While up to 2020 the food waste initiatives in England had been on a purely voluntary basis throughout the food supply chain, the Government’s Resources and Waste Strategy [18] published in December 2018 and the subsequent early 2019 consultation papers on different aspects of waste management suggested that there may be government intervention in future. However, it is likely that for the period up to 2022, there would be no legislation, and the government would instead rely on exhortation and voluntary action by businesses to reduce food wastage. This Laissez-faire approach for England is in stark contrast with the food waste legislation and regulations introduced by all three of the UK’s devolved administrations (DAs). The UK’s devolved administrations—Northern Ireland, Scotland, and Wales—have adopted their own policies to tackle food waste. In addition to utilizing the WRAP-initiated Love Food Hate Waste model and its promotional initiatives, these DAs also have their own regulations and campaigns to promote food waste prevention by citizens and businesses. In Northern Ireland (NI) the Food Waste Regulations (Northern Ireland) 2015 adopted the Scottish approach to regulate the food waste disposal of any business that generates more than 5 kg of food waste each week. This legislation requires these businesses to segregate and present this food waste for separate collection, treatment, and recycling. The larger businesses generating more than 50 kg/week had to fulfill this requirement in 2016 and smaller ones from 2017.

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From April 2017 there was a mandatory requirement [19] for NI councils to provide households with containers for food waste for separate collection. These containers are collected on a weekly basis. In itself, this change in the NI segregated waste collection system increased the proportion of household waste recycled by 5% (2018 compared with 2017) and also reinforced the recycling message to residents for dry recyclable wastes to be segregated. Scotland was the first of the UK’s devolved administrations to introduce food waste legislation; the Waste (Scotland) Regulations 2012 requires all premises that generate more than 5 kg of food waste each week to have this collected separately and treated, obviously with the larger generators having to conform sooner than smaller ones. However, in recognition of its mountainous topography and the difficult road communication network, there are provisions that allow companies not to have a collection if they are in very remote locations. As for household food waste collections, these are being introduced at a slower rate than in NI and Wales because there are so many isolated rural settlements where distances to reprocessing facilities would be both prohibitively expensive and environmentally counterproductive. Nevertheless, despite these physical and operational constraints, the Scottish Government in its 2018 Climate Change Plan set itself an ambitious target for food waste reduction. The Scottish Government is aiming for a reduction of food waste by 33% by 2025 [20]. In Wales, every household is required to be provided with a separate food waste collection, and the Welsh Assembly Government (WAG) allocated considerable financial resources to enable Welsh councils to purchase equipment, including specialist vehicles, collection bins, and kitchen caddies, for their collections [21]. In addition, WAG had provided finance to companies to treat the collected food waste through AD in three plants that serve the whole of Wales. In 2017 the Welsh Government Cabinet Secretary for Environment and Rural Affairs announced ambitious plans to halve food waste in Wales compared with a baseline figure for 2006–07 [22]. However, at late 2019, this target had not been endorsed by the Welsh Government.

2.2 France In contrast to England, which accounts for 90% of the UK’s population, which has relied purely on voluntary initiatives to persuade both consumers and industry to institute measures to reduce food waste, the French position has been to use legislation and regulation to require various commercial sectors that generate surplus food and food waste to prevent, redistribute, and treat food waste for productive purposes. Since 1988 in France, there has been an incentive for restaurants and supermarkets that have been provided with a tax reduction of 60% of the value of all donated food. Nevertheless, there was a feeling that more needed to be done so in 2012, the French Government introduced a law to force supermarkets to redistribute surplus food. In 2016 France became the first country in the world

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to ban supermarkets from disposing of any unsold surplus or waste food. The significance of this legislative move was significant because France redistributes up to 10 times more surplus food from supermarkets compared with the United Kingdom.

2.3 Denmark Denmark is interesting because its policy focuses attention on the work of one individual, who came across from Russia as an immigrant. Selina Juul, a graphic designer, was appalled to see the amount of food that was being discarded by supermarkets. As a result of her campaigning, there has been a reduction in food waste generation in Denmark. Following her initiative, there were a number of other community projects that are designed to prevent food waste, especially fresh fruit and vegetables. The Danish Government produced a national waste policy in 2014. The ambition in Denmark without Waste II: a waste prevention strategy [23] is to recycle more and incinerate less, given that only 2%–3% of residual waste is landfilled. Therefore the Danish Government’s food waste policy sits within that strategy in a section on generating less food waste. The overall aim of the strategy is to recycle 50% of waste by 2022 from the seven focus fractions identified within the CEP, mainly by increasing the separation of organic waste from households, albeit only 32 municipalities had food waste separation collections in 2017. The food waste is being processed by anaerobic digestion (AD). In 2019 all 98 Danish municipalities had food waste collections. Denmark is developing a comprehensive network of AD plants so that an increasing range of organic wastes, from pig slurry to food waste from households, can be utilized for the production of methane. This biomethane is mainly used currently for the generation of electricity but also, like neighboring Sweden, as a fuel for busses and waste collection vehicles. The Danish capital, Copenhagen, wants to be at the forefront of environmental progress. One of the main objectives of Copenhagen’s overall environmental planning is to ensure that Copenhagen is carbon neutral by 2025. The Cirkular Copenhagen—Resource and Waste Management Plan 24 [24] developed by the city showed how the collection and treatment of food waste would assist with that broader objective. The current population of Copenhagen is in excess of 600,000 and is growing at 2% pa with 90% of households living in apartments. There is collection of separated recyclable wastes at households with the waste collection fee being included as a separate item in households’ property tax demand. The only way of reducing this fee is to opt for a reduced collection of residual waste, but this is obviously mainly available to the small minority of single-family households. The estimated cost increase for the annual waste fee was €120 per household to fulfill this ambitious strategy. The target for 2024 was for 70% household waste to be recycled compared with the 45% target for 2017. From 2017 analyses the input into the previous and

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current incineration facility shows that of the inputs there were present in the following proportions: • 41% biowaste—mainly food waste • 35% recyclable—not sorted at the household • 14% incinerable—disposable diapers and vacuum cleaner bags, for example • 5% nonincinerable—for example, material from home improvement • 1% special treatment—hazardous waste that should be separated for treatment This plan involved a range of measures, including food waste collection for all households. To make food waste recycling more acceptable to residents living in apartments, the city not only provides colorful caddies to sit on the work surface but also supplies compostable bags on demand to enable food waste to be carried down to the food waste bin in the apartment courtyard food waste collection containers. From there the waste is collected by a split bodied refuse collection vehicle for onward bulking prior to transport to outlying AD facilities. In contrast to Copenhagen’s collection system for most municipalities in Denmark, the system is very simple. Residents tie their organics bag to the handle of their residual waste bin where it is accessed by the refuse collection operative staff and put into a separate compartment in the refuse collection vehicle for onward transport to a nearby AD plant. In Copenhagen, up until 2021, the city will not have an AD plant within its boundaries so that the food waste collected had to be delivered to AD facilities elsewhere. Also from an operational perspective, while the use of compostable bin liners might look the most appropriate option for households, the AD plant operators find the bags problematic because they do not degrade sufficiently rapidly in a single-AD processing cycle.

2.4 Italy Italy also has a focus on the utilization of food waste through AD, but in this case, it is mainly due to the government’s generous incentives available for the production of renewable energy sources. Therefore not only it is food waste that is being processed in its AD plants, but also the operating companies also process green wastes, which previously would have been composted, to maximize the output of biomethane from these plants. Italy also has its food waste champion in the form of the Michelin 3-star chef Massimo Bottura, who uses the medium of food waste prevention for social cohesion purposes as well as environmental benefit. In 2016 Italy became the second EU MS after France to adopt legislation to tackle the food waste issue. As with other countries, although there is a heightened public awareness of food waste issues, the reductions have been slow to come through. Surplus food redistribution by retailers and from municipal markets, however, is increasingly common. The city of Milan has a population of 1.3 million and is served by a publicprivate company AMSA, who also service 12 neighboring municipalities with a

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combined population of 260,000. In the Italian region of Lombardy, there are 1700 municipalities, and Milan was one of the last places in the region to adopt a food waste separation system. In 2011 Milan had reached a 35% separate collection rate, but the Italian legislation required a source separation rate by municipalities of 65% and a recycling rate of 50%. The decision was taken by the mayor to have food waste collected on a door-to-door basis paralleling what was already the position for dry recyclables: a yellow bag for plastics and metals, a white bin for paper and board, and a green bin for glass. The first step was to go over to the use of a transparent bag for residual waste rather than a black bag city wide. This change increased the separation of recyclables by 2%. In November 2012 the SW quadrant of the city was provided with the equipment and information to start recovery of food waste from households. Both were delivered by the operative staff undertaking the service. Most properties have 120-liter brown bin(s) (35 liter bins for smaller properties) and a 20-liter kitchen caddy and an initial 25 bioplastic bin liners for each household. After the initial bioplastic bin liners have been used, because from 2010 Italy adopted a policy of only allowing the use of bioplastic carrier bags for food shopping in the future, consumers could use these bags as their caddy liners. A wide range of communication media was used to promote the system and encourage full participation, which in any case is mandatory. Thereafter, every 6 months, a further quadrant was provided with the organic collection service. The food waste bin and the residual waste bags are collected twice weekly on the same day. Previously, there had been a residual waste collection, at least twice a week to all parts of the city. Analysis has shown that there is little contamination of the biobins with 95% food waste on average. The main contaminants are plastics and disposable nappies. The great advantage that residents in properties in apartments in Milan have is that they have courtyards for the storage of bins and concierge services so that the bins can be put out on the pavement just before the collection time and to move empty bins immediately after collection. New buildings are required to have specific space allocated for waste bins and arrangements for setting out the bins. The bins are checked by waste collection operative staff and fines issued if contamination is found in any of the source-separated containers. However, the main checking mechanism is really the social control that is exercised by neighbors within the block and the concierge inspecting the bins before setting them out.

3 North America—US Federal Government, State and Canadian Food Waste Policy Initiatives 3.1 US Federal Government The US Federal Government has no mandatory control over food waste matters. However, in 2017 in conformity with the UN SDG 12.3 target, the US Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) announced the first ever US goal to reduce food waste, by half by 2030 [25].

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Through the US 2030 Food Loss and Waste Reduction goal (2030 FLW reduction goal), the United States had ambitious aims to feed the hungry, save money for families and businesses, and protect the environment. Led by the USDA and EPA, the federal government was seeking to work with communities, organizations, and businesses together with state, tribal, and local governments to reduce food waste. Since the time of this announcement, there appears to have been no federal finance or any legislative measures enacted to ensure the achievement of the goal [26]. The measurement of the progress toward success of the 2030 FLW reduction goal even uses two different baselines: • The EPA’s Advancing Sustainable Materials Management: Facts and Figures, which is published annually but with several years’ delay, provides an estimate of the food waste going to disposal from households, commercial premises, and institutional sources. Preconsumer food waste generated by manufacturing and packaging of food products is not included in these estimates. 2010 was chosen as the baseline with 100 kg of food waste per person sent for disposal. Therefore the 2030 FLW reduction goal is 50 kg per person. • The USDA’s Economic Research Service has estimated the amount of available food supply that went uneaten at the retail and consumer levels for 2010 at 31% of the food supply, equating to 63,232,800 tonnes in weight and with an estimated value of €195B. The 2030 FLW reduction goal using this measure is approximately 30,163,900 tonnes. With a growing population, 0.7% pa as at 2017, clearly, the second measure of success would be the harder to achieve.

3.2 USA State and Local Governments As with other aspects of waste management and regulation in the United States, responsibility for policy and legislation rests with the individual states and even city and municipal authorities. Therefore policies and practices vary widely. California, for example, already has a long-standing waste management goal of 75% diversion from disposal through source reduction, recycling, and composting. Because California’s residents discard 6 million tonnes of food waste each year, around 18% of all household waste, food waste recycling would be essential to meet that target. California’s 2018 Commercial Organics Recycling law requires businesses to recycle their organic waste. At a municipal level in California, there are a number of options that are being adopted to ensure the recovery of food waste from households. In parallel, on the other side of the continent, New York City’s Department of Sanitation (DSNY) has mandated larger commercial businesses to separate their organic waste, which also includes food-soiled paper and certified compostable products. The severity of the fines for businesses failing to undertake organic separation can be up to $1000 compared with improper sorting of waste into recyclable and residual waste at $25. The reasons for such draconian actions are to meet a number of environmental objectives, including an 80% reduction

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in GHGs by 2050, phasing out landfill by 2030, and diverting organic waste to AD processing. As with other administrations, DSNY’s regulations are applied to larger waste generators initially. Therefore, from July 2016, these included food services in hotels with more than 150 rooms, arenas, and stadia with seating for at least 15,000 people, larger food manufacturers and wholesalers. From August 2018 a range of food service establishments and larger retail outlets were added. However, the DSNY only expected 50,000 tpa of the 650,000 tpa of commercially generated food waste to be diverted to AD. This was because of the comparatively small number of businesses affected, only around 2000 in total.

3.3 Canada In Canada a report The Avoidable Crisis of Food Waste was produced in January 2019. This report showed that more than half of food produced in Canada is wasted (58%). The cost amounted to €1200 per household [27]. In Canada’s case the report showed that almost 5 million tonnes of food were lost or wasted during processing and manufacturing with less, about 2.4 million tonnes, discarded by consumers. In contrast to the US Federal Government, the Canadian Federal Government in its budget for 2019 committed €90 million over 5 years to developing a food policy for Canada. However, as with most countries, the development of Canada’s food waste policy lags behind what either communities and local activists are already engaged in trying to tackle the issue. As an example, in Canada, the Toronto Food Policy Council has been working on food-related issues since 1991, albeit the food waste problem is only one of a number of issues that are being addressed within its overall food strategy [28].

4 Australia In November 2017 the Australian Federal Government launched its National Food Waste Strategy working toward halving Australia’s food waste by 2030 in conformity with the UN SDG target 12.3 [29]. The Australian Government estimated that 5.3 million tonnes of food waste was being generated each year and at 40% is higher than the international average for developed economies. The Australian Government estimated consumers discarded 3.1 million tpa of food. This amounted to an average household discarding of €3500 of unused food each year. In addition, a further 2.2 million tpa was discarded by the commercial and industrial sectors. In Australia, it is South Australia (SA) that has taken the lead in trying to tackle food waste problem. In Adelaide the €100 million Fight Food Waste Cooperative Research Centre [30] has been set up as a national research center. The reason that South Australia was chosen as the site of the CRC is that it was already a leader in sustainability initiatives including beverage container recovery through deposit return systems and banning plastic bags. The CRC has three

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targeted research programs: reduce, transform, and engage to reduce food waste and create behavioral change.

5 Conclusions and Perspectives While there are positive perspectives regarding the development and implementation of food waste policy internationally, the rate of real action and progress has to date been very slow. The evidence is that there are more problems than normally experienced with other environmental issues because national governments that are responsible for the implementation of the UN SDG 12.3 target are continuing to sacrifice these priorities to other policy imperatives. The importance of the climate change SGD target has obviously been recognized internationally, but as with the food waste target, national government response has not been universal, and there are problems to ensure that the food waste issue is tackled with robust and comprehensive policies. The individual’s response to food waste has not often been as encouraging as policy makers would have wished because, unless faced with famine conditions, most people are not addressing this issue in their day-to-day behavior. Often in developed and transition economies, the proportion of disposable income spent on food is declining, and therefore the impetus to reduce food waste requires drivers other than financial incentives. Perhaps the answer lies with all of the actors within the food supply chain appreciating that addressing the overwhelming global challenge of climate change that faces the world that the food waste issue provides an unprecedented opportunity to influence citizens’ behavior to radically alter their food purchasing, storage, and eating habits. Governments need to regulate on the issue of food waste to ensure that in future this issue is linked to climate change. Hopefully then, there would be a recognition that there would be a better interface to ensure that the issue over which citizens have a degree of control can contribute to addressing the most urgent global issue faced by the world.

REFERENCES [1] FAO, Food Wastage FootPrint: Impacts on Natural Resources, Food and Agricultural Organisation, Rome, Italy, 2013. [2] UN, The Sustainable Development Goals Report, https://unstats.un.org/sdgs/report/ 2016/The%20Sustainable%20Development%20Goals%20Report%202016.pdf United Nations, 2016. [3] WRAP, Strategies to Achieve Economic and Environmental Gains by Reducing Food Waste, Waste and Resources Action Programme and the Global Commission on the Economy and Climate, Banbury, Oxfordshire, UK, 2015. [4] T. Chen, J. Yiying, D. Shen, A safety analysis of food waste-derived animal feeds from three typical conversion techniques in China, Waste Manage. 45 (2015) 42–50. [5] C. Hanson, P. Mitchell, The Business Case for Reducing Food Losses and Waste, Champions 12.3, London UK, 2017. [6] E. Facchini, et al., Food flows in the United Kingdom: the potential of surplus food redistribution to reduce waste, J. Air Waste Manage. Assoc. 68 (9) (2018) 887–899.

References

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[7] WRAP, BSI PAS 110 Specifications for Digestate, http://www.wrap.org.uk/content/bsipas-110-producing-quality-anaerobic-digestate, 2016 Bicester, Oxfordshire, UK. [8] J. Parfitt, M. Barthel, S. Macnaughton, Food waste within food supply chains: quantification and potential for change to 2050, Philos. Trans. R. Soc. B 365 (2010) 3065–3081. [9] B. Kim, R. Neff, R. Santo, J. Vigorito, The Importance of Reducing Animal Product Consumption and Wasted Food in Mitigating Catastrophic Climate Change, Johns Hopkins Center for a Livable Future, Baltimore, MD, 2015. [10] FUSIONS, Estimates of European Food Waste Levels, http://www.eu-fusions.org/ phocadownload/Publications/Estimates%20%of%20%European%20%food%20% waste%20%levels.pdf Food Use for Social Innovation by Optimising Waste Prevention Strategies, 2016. [11] LWARB, TRiFOCAL Project – ‘Small Change, Big Difference’ London-Wide Digital Campaign Brief – February 2018, lwarb.gov.uk/wp-content/uploads/2018/02/ TRiFOCAL-digital-brief-Inc-Apx.pdf London Waste and Recycling Board, London, UK, 2018. [12] WRAP, Food Waste Collection Guidance, http://www.zerowastescotland.org.uk/sites/ default/filesinformation%20on%20collecting%20food%20waste%20for%20recycling. pdf Waste and Resources Action Programme, Banbury, Oxfordshire, UK, 2009. [13] WRAP, Food Waste From Commercial and Industrial Sources, http://www.wrap.org.uk/ content/food-waste-commercial-and-industrial-sources, 2016. [14] WRAP, The True Cost of Food Waste Within Hospitality and Food Service, http://www. wrap.org.uk/sites/files/wrap/The%20true%20%Cost%205of%20%Food%205Waste% 20%within%20%Hospitality%20%andFood%20%Service%20%Sector%20%Final. pdf, 2013. [15] WRAP, Hospitality and Food Service Agreement final report, http://www.wrap.org.uk/ content/hospitality-and-food-service-agreement-taking-action-waste, 2017. [16] GLA, FoodSave Project, London Waste and Recycling Board, London, UK, 2015. [17] WRAP, wrap.org.uk/sitesfiles/Coop%20Potatoes%20pathfinder%20Project_Case% 20Study, 2017. [18] DEFRA, Resource and Waste Strategy, Department of the Environment, Food and Rural Affairs, UK Government, 2018. [19] Northern Ireland, The Food Waste Regulations (Northern Ireland) 2015, legislation.gov. uk/nisr/2015/14/made, 2015. [20] Scottish Government, Scottishgovernment/policies/managingwaste/food-waste, 2018. [21] Welsh Government, Preventing Food Waste, Welsh Government Environment and CountrySide, Waste and Recycling, Prevention and Minimisation, (2015). Cardiff, Wales. [22] Welsh Government, gov.wales/plans-halve-food-waste-announced-lesley-griffiths, 2017. [23] Danish Government, Denmark Without Waste II: A Waste Prevention Strategy, Danish Environmental Protection Agency, 2014. ISBN 978-87-93435-27-8. [24] Kobenhavns Kommune, Cirkular Copenhagen – Resource and Waste Management Plan 2024, http://kk.sitesitera.dk/apps/kk_pub2/index.asp, 2019 Copenhagen, Denmark. [25] US EPA, 2030 Food Loss and Waste Reduction Goal, epa.gov/sustainable-food/UnitedStates-2030-food-loss-and-waste-reduction-goal, 2017. [26] US EPA, www.epa.gov/sustainable-management-food/united-states-2030-food-lossand-waste-reduction-goal, 2019 Update 21 February 2019, Environmental Protection Agency, USA. [27] Second Harvest, The avoidable crisis of food waste, Second Harvest and Value Chain International report, Toronto, Canada, (2019). [28] City of Toronto, Toronto Food Strategy: 2011 Update, Toronto Board of Health, Toronto, Canada, 2011. [29] Australian Government, National Food Waste Strategy, Department of the Environment and Energy, 2017. [30] FFW CRC, Annual Report 2018/2019, Fight Food Waste Cooperative Research Centre, Adelaide, South Australia, 2019.

Chapter | Fifteen

Life-Cycle Assessment and Sustainability Aspects of Food Waste Pedro Brancolia, Kim Boltona, Kamran Roustaa, and Mattias Erikssonb Swedish Centre for Resource Recovery, University of Bora˚s, Bora˚s, Swedena Department of Energy and Technology, Swedish University of Agricultural Science, Uppsala, Swedenb

1 INTRODUCTION Huge quantities of food are generated globally each year, of which approximately one-third is never consumed [1]. According to the Food and Agricultural Organization (FAO) of the United Nations, this amounted to 1.3 billion tonnes of edible food waste in 2007 [1]. Similarly the European Union generates approximately 88 million tonnes of food waste [2], and Sweden generates 1.3 million tonnes of this waste [3]. The global food demand is expected to increase by 70% by 2050 [1], which will further increase the amount of food waste. This food waste has a large impact on all three aspects of sustainable development: social, economic, and environmental. At the same time that food is being wasted, 795 million people suffer from undernourishment [4]. This raises ethical concerns and increases the importance of reducing food waste or channeling surplus food to relevant geographical regions before it is wasted. In addition, a recent report by the Intergovernmental Panel on Climate Change (IPCC) [5] confirmed that global warming, that is caused by, among others, food waste, diminishes food security. For example, increased rates of global warming are projected to lead to floods and droughts that will occur more often and with larger magnitudes [5]. Global warming is also expected to lead to smaller crop yields and nutritional content, especially in some regions of sub-Saharan Africa, Southeast Asia, and Central and South America [5]. Warming of the oceans is already posing risks to fisheries and aquaculture, especially in low-latitude regions [5]. 395 Current Developments in Biotechnology and Bioengineering. https://doi.org/10.1016/B978-0-12-819148-4.00015-4 Copyright © 2021 Elsevier Inc. All rights reserved.

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The economic and environmental impacts are exacerbated by other processes and products involved in the food value chain, such as transport and packaging. That is, a large part of the food waste is generated at the end of the value chain, for example, in households, and the extra costs and environmental impacts of transporting and packaging this food are to no avail. For example, in Sweden, 75% of the food waste is at households (excluding agricultural food waste where the amounts are not known) [3]. At the European level, about 47 million tonnes of food is wasted by households compared with a total food waste loss of 88 million tonnes [2]. This food has been packaged and transported throughout the supply chain, which increases its economic costs and environmental impacts. It is difficult to estimate the costs associated with food waste. However, Kaza et al. [6] have estimated the operating costs for integrated waste management of municipal solid waste, including collection, transport, treatment, and disposal. Although this is for the total amount of municipal solid waste, of which food and green waste is 44%, it does not take into account the upstream costs (before disposal). According to Kaza et al. [6], 2.01 billion tonnes of municipal solid waste are generated globally per year. About 34% of this is generated in high-income countries, where the operating costs generally exceed USD100 per tonne. Lower-income countries spend about USD35 per tonne. This gives a total, global annual operating cost of USD155 billion. Although 44% of solid municipal waste is food and green waste, it is difficult to extrapolate how much of this USD155 billion is due only to this waste fraction. However, global municipal solid waste is expected to grow to 3.40 billion tonnes by 2050 [6], increasing the cost of waste treatment, including the management of food waste. Also, although it costs low-income countries less to handle the waste, these countries spend 20% of their budget on waste treatment (compared with 10% in middle-income countries and 4% in high-income countries). This is one of the largest budget posts for these countries, in spite of the fact that 90% is openly dumped or burned [6]. Improving the waste treatment, together with the projected increase in the amount of waste, is therefore expected to further increase the economic costs. Economic costs of food waste are, of course, borne not only by the actors, usually municipalities, that treat the waste but also by the actors that generate the waste. The Food and Agriculture Organization (FAO) of the United Nations estimated the global expense associated with food waste is USD 1 trillion in economic costs, USD 700 billion in environmental costs, and USD 900 billion in social costs [7]. The FUSIONS project [2] estimated a cost of €143 billion (USD 160 billion) associated with food waste in the European Union. A report by WRAP [8] showed that 4.2 million tonnes of avoidable food and drink is wasted in UK households each year, worth £12.5 billion (USD 16.3 billion). Food waste, including the associated processes and products such as transport and packaging, has a negative impact on the environment. This ranges from climate change to acidification, land use, and depletion of natural resources [9–11]. Food waste contributes to 8% of the total global warming potential

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[12], and 1.4 billion hectares of land [1], which is 30% of the world agricultural land area, are used to produce food that is not consumed.

2 SUSTAINABLE DEVELOPMENT GOALS AND THE WASTE HIERARCHY Since food waste affects all three aspects of sustainable development, it is not surprising that several of the United Nations’ 17 Sustainable Development Goals are directly or indirectly linked to reduction and proper management of food waste. Table 1 shows the four goals that are probably the most directly coupled to food waste. In addition to the goals shown in Table 1, the following goals are also related to food waste and its management: • Good health and well-being (Goal 3): Food waste that is discarded in dumps or uncontrolled landfills can result in emissions of leachates into drinking water and can catalyze the spreading of diseases. • Quality education (Goal 4): Households, especially in developed nations, need to be educated on the importance of reducing overconsumption of food and their role in the waste management system.

TABLE 1 Four United Nations’ Sustainable Development Goals That Are Directly Coupled to Food Waste. Proper management of food, especially the edible fraction, is important not only to reduce economic costs and environmental burdens but also to provide food security. The proper management of uneaten yet edible food will become even more important given that the global food demand is expected to increase by 70% by 2050 [13]

It is predicted that 4.3 billion people will live in cities by 2025 [14]. This is an increase of 43% from 2012. Hence, there will be a dramatic increase in the supply of food to urban areas, with a concomitant increase in food waste. This waste must be seen as a resource that can be used to produce valuable products, such as compost and bioenergy, which are used within the city or in surrounding areas Food production requires huge amounts of water, land usage, and other resources for, for example, fertilizers and pesticides. Although the increase in food demand will increase the need for resources, this has to be achieved within the limited resources that are available on the planet. In addition, food production and management yield emissions that impact the environment. Responsible consumption and production can only be obtained by reducing overconsumption and minimizing food waste. Proper management of the waste that is inevitable must yield products that can be alternatives for those that are made from virgin materials. One of the subgoals (12.3) is that per capita food waste at the retail and consumer levels must be halved by 2030 and that food losses along the entire supply chain must be reduced Continued

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TABLE 1 Four United Nations’ Sustainable Development Goals That Are Directly Coupled to Food Waste—cont’d Food waste contributes to 8% of global warming [12]. Hence, food that is produced for human consumption but that is never eaten leads to almost onetenth of the planet’s global warming. Reducing food waste and implementing proper management schemes for food waste have an enormous potential to reduce the impacts of climate change

• •

Clean water and sanitation (Goal 6): See discussion of Goal 3. Affordable and clean energy (Goal 7): This goal emphasizes the need for energy from renewable sources, which includes energy from proper management and treatment of food waste. • Partnerships for the goals (Goal 17): Proper management of food waste must be practiced in all countries to address sustainable development challenges such as global warming. This requires global partnerships. The European Union has developed a strategy, called the waste hierarchy, to manage most types of waste [15]. Similar frameworks have been developed, such as the food waste hierarchy, designed to prioritize actions to prevent and divert food waste [16]. This is illustrated in Fig. 1. The method of treating waste that is higher up in the hierarchy is preferred. However, there are situations when the hierarchy does not represent the best treatment alternative, and deviations from it are allowed if supported in a scientifically robust manner. Often the life-cycle assessment (LCA) methodology is used to support such deviations. According to the food waste hierarchy, reduction in the amount of waste is the most preferred option. This can be achieved by, for example, reducing overconsumption and aligning food production with food demand. The remaining waste treatment methods are discussed in more detail in the next section. In general, according to the food waste hierarchy, the option that is preferred after prevention is to use the surplus food to feed people. This could be, for example, via donation of the surplus food to food banks, soup kitchens, and shelters or by reprocessing the food surplus into other food products. The donated or reworked product has the same function as the virgin product, and in this sense, there is no loss in value. If the food cannot be used for feeding people, another reduction strategy is to use it as animal feed. Following this option the waste should be used for industrial uses such as recovery energy in the form of biofuel and then composting. The least preferred option is landfill, with controlled landfilling (with heat and electricity recovery) being preferred to uncontrolled landfilling or dumping. Preferred waste treatment methods have also been described in other terms. For example, the three Rs—reduce, reuse, and recycle—have been used as a

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FIG. 1 The food waste hierarchy. Adapted from USEPA, United States Environmental Protection Agency – Food Recovery Hierarchy, 2018 [cited 18.02.11]; Available from: https://www.epa. gov/sustainable-management-food/food-recovery-hierarchy.

strategy for waste treatment. Similar to the waste hierarchy, reduction is preferred to reuse that, in turn, is preferred to recycling. These three waste treatment methods are preferred to disposal. Another relevant term is the circular economy, for which the European Union has developed an action plan [17]. This terminology emphasizes the strategy to continually reuse or recycle discarded products without a loss in quality. This is of particular interest to food waste, since a substantial amount of research is presently focusing on producing products that may, in fact, have a larger value than the original food products. For example, research is being conducted into producing food stuffs that have a large protein content compared with the food waste from which they are produced [18, 19].

3 MANAGING FOOD SURPLUS AND FOOD WASTE Fig. 2 shows different routes for treating surplus food. The FUSIONS project, funded by the European Union, defines food waste as the fraction removed from the food supply chain and sent to disposal or recovery, that is, anaerobic digestion, composting, crops plowed in or not harvested, bioenergy, incineration, cogeneration, sewer, landfill, and discards [20]. Hence, reduction and reuse, as well as recycling into new food products, which are part of the food waste hierarchy, are not considered as waste treatment methods according to the definition in the FUSIONS project. These methods could be regarded as methods to manage surplus food before it is classified as waste. Also, Eriksson et al. [21]

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FIG. 2 Figure of different routes for prevention, valorization, and disposal of food surplus and waste. The right column lists the products obtained from the different management methods.

and Eriksson et al. [22] have shown that each degradation in value of the surplus food normally corresponds to less environmental savings when reused, so the closer to the source food waste can be prevented, the better. Donating surplus food is usually associated with giving away food free of charge or at a drastically reduced price. Similar processes that can potentially avoid food waste are to sell surplus food, that is, from restaurants or supermarkets, at a reduced price. Examples of these ways to manage surplus food are given in the succeeding text. These management schemes potentially have an impact on all three aspects of sustainable development. Citizens that accept food donations are typically in need of these types of social actions and would otherwise not have access to adequate quantities of food with the required nutritional value. These citizens, including those that purchase from restaurants or supermarkets at reduced prices, also have an economic incentive to be involved in these schemes. Similarly the restaurants or supermarkets have an economic motivation, since they can sell the surplus food at reduced prices instead of gaining no income for this food and paying for the treatment of the resulting food waste. There is also a potential reduction in environmental impacts with food donation and sales at reduced prices. This food is consumed instead of having to be

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treated as food waste, with the assumption that it replaces food that otherwise would have to be produced for these citizens [21, 23]. However, there is a risk that food donation and sales at reduced prices can shift the waste from the donators, restaurants, and supermarkets to the citizens. For example, food that is received by charity organizations may end up as food waste, and the extra economic costs and environmental impacts associated with transport, etc. are to no avail. Similarly, food that has been bought at reduced prices (or buy two and pay for one) may lead to overconsumption and the resulting increase in waste by households. There are numerous examples, from international to local initiatives, of food donation. International organizations include the Global Foodbanking Networka and the World Food Programme.b Matmissionenc is an organization in Sweden that gathers food that is donated from supermarkets and that sells it at reduced prices to citizens with low income. All of these initiatives contribute to sustainable development by channeling surplus food to those having lower incomes, at the same time that the environmental impacts of food waste are prevented. Karma is an organization that was launched in 2016.d They use digital technology, mainly via smartphones, to sell surplus food from restaurants, cafes, hotels, bakeries, and supermarkets directly to customers. As discussed in Strid and Eriksson [24], a supermarket sold meat cuts after passed best before date to a catering unit that used this meat in different dishes. Since the waste generation varied, the supermarket froze the meat to prolong the shelf life so that the catering company could have efficient logistics. Approximately 20 kg of meat cuts per store per month were sold, and since it could replace pork and beef at the catering company, it resulted in a net saving of approximately 300 kg CO2eq per store per month. Food surplus can also be reused to produce new food products and is therefore not waste according to the FUSIONS definition. An example is the use of surplus bread that is used when baking new bread. Another example, described in Eriksson and Spa˚ngberg [23], is where people in a work training program at the social company Macken in V€axj€ o used surplus fruits and vegetables donated by local supermarkets to produce chutney with a much longer shelf life than the original fresh produce. The chutney was packed and sold as a premium product to finance the redistribution scheme, but even though the environmental and social benefits were high, the volume produced was not enough to make it economically feasible. The business model was therefore not economically sustainable.

a

https://www.foodbanking.org/. https://www1.wfp.org/overview. c https://www.stadsmissionen.se/vad-vi-gor/matmissionen. d https://thespoon.tech/karma-turns-surplus-food-from-restaurants-and-grocery-stores-intocheap-meals/. b

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Another method to avoid food waste, according to the FUSIONS definition, is to use it as animal feed. This would substitute the need for conventional types of animal feed, such as those based on soybean and barley [25] that, based on a previous LCA, is expected to yield significant environmental benefits [26]. However, as with donation, other aspects of sustainable development are important. For example, in Europe, there are strict regulations about the type of surplus food that can be used as animal feed [27]. In many cases, surplus food that contains proteins that come from animals cannot be used as animal feed. The regulations are particularly strict for animals that are being raised for human consumption. In spite of the possibility to use surplus food as animal feed, many actors that generate waste do not use this option. This is mainly because these actors perceive the legislation as complex and cumbersome to implement, at the same time that it is far simpler to send their food waste to other treatment facilities, such as anaerobic digestion (AD) plants [27]. As shown in Fig. 2, food waste can be used to produce compost, biofuel, heat, and electricity via combustion or to produce methane from controlled landfilling. Composting may be considered as recycling, since one produces a new product from the food waste. According to the waste hierarchy in Fig. 1, this is preferred to controlled landfilling but not to biotreatment. This is in agreement to the Swedish strategy that at least 40% of all food waste must be treated so that not only the nutrients but also the energy are recovered. Recycling the food waste via composting harnesses the nutrients, but the heat generated during composting is lost. This is therefore less preferable to biotreatment where both the energy (biofuel) and nutrients (in the digestate) are utilized. It can also be noted that biotreatment can yield different types of biofuels, such as ethanol and methane. The type of product that is selected may significantly affect the environmental benefits of the waste treatment. For instance, the production of bioethanol is accompanied by the by-product dried distiller’s grains with solubles (DDGS), which is sold as animal feed [26]. DDGS can therefore substitute other types of animal feed. In contrast, fermenting food waste to methane does not have any protein-rich by-products, but rather a digestate that can substitute mineral fertilizers. The environmental impact of these two alternatives may therefore differ significantly. The least preferred treatment methods for food waste are combustion without retrieval of heat or electricity and landfilling without methane recovery and dumping. As described in Eriksson and Spa˚ngberg [23], incineration of a fuel with a high water and low energy content, such as waste fruits and vegetables, requires input of energy to burn. Even worse is landfilling of organic matter that produces methane under oxygen-free conditions. Since methane is a more potent greenhouse gas than carbon dioxide, the landfill generates higher global warming potential than composting and incineration. Different methods to collect the methane so it can be flared or used for energy production reduce the impact from the landfill [28] but only to a limited extent. According to Eriksson et al. [21], the largest leap forward in improving food waste management is to move from landfill to any other technique. For instance, in Bora˚s, a medium-

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sized Swedish city, separation of food waste was started at the beginning of the 1990s. This separation resulted in the production of biogas and composting from the food waste and reduced landfilling dramatically. According to Rousta et al. [29], this biological treatment contributed to about 20% of the total household waste management. This illustrates the improvement of waste management toward higher levels of the waste hierarchy. In addition to the conventional methods of food waste treatment described earlier, other techniques are under development. One example is the production of fungi from food waste [18, 26]. This fungi, which grows while producing ethanol, is protein rich and can be used as animal feed [18] and, potentially, even food for human consumption [30]. Hence, one is using food waste to produce a protein-rich edible material that may have more (nutritional) value than the original food. This is in line with the strategy of a circular economy, and if the value of the recycled food increases, it goes beyond the circular economy. Similarly, food waste can be used to cultivate flies [19], which can be used as protein-rich animal feed.

4 THE LCA METHODOLOGY There are many excellent texts on LCA, for example, Baumann and Tillman [31], and this contribution merely provides a simplified discussion and summary. The holistic approach of LCA, which considers the whole life cycle of the system, has the advantage of reducing the risk of shifting environmental impacts from one part of the system to another and hence reduces the risk for suboptimization of the system [32, 33]. The European Union considers life-cycle assessment as the best framework currently available for the quantification of environmental burdens of products [34]. LCA is a method to calculate the environmental impact of a product or a process. For example, one may want to calculate the environmental impact of 1 kg of beef (beef is a product) or the environmental impact of treating 1 kg of waste beef by AD (AD is a process). When doing an LCA of a product, it is preferable to consider the environmental impact over the entire life cycle of the product. This is often called a “cradle to the grave” LCA, and one accounts for the natural resources that one removes from the earth, emissions when one makes and uses the product, and the impact when one treats the product as waste. Fig. 3 shows the four steps that comprise the LCA procedure. Note that LCA is not always a linear procedure. This is illustrated by the dashed lines in Fig. 3. To be efficient, it is good to be as thorough as possible when defining the goal and scope and when performing the inventory analysis and impact assessment. However, knowledge gained at a later stage during the LCA may affect an earlier stage, and therefore one needs to return to the earlier stage. For example, during the interpretation (fourth step), it may be revealed that the fertilizer used for growing the food crops has a large environmental impact. The person commissioning the LCA (e.g., the supermarket owner that

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Life-Cycle Assessment and Sustainability Aspects of Food Waste

FIG. 3 The LCA procedure.

buys the food) may want to know if the use of an alternative fertilizer could reduce the environmental impact. Hence the goal and scope of the LCA would be changed, and one returns to the first step and repeats the LCA for the second fertilizer.

4.1 Goal and Scope Definition 4.1.1 GOAL In the first step the goal of the LCA must be decided. For example, an LCA for bananas may aim to identify what stages of the bananas life cycle are the most damaging to the environment. Is it the growing of the bananas (including the possible use of fertilizers and pesticides), the transportation, or something else? 4.1.2 FUNCTIONAL UNIT The functional unit must be identified. For example, is it 1 kg of banana waste in a local supermarket or is it the total amount of bananas that is wasted over 1 year at this supermarket? The functional unit is critical if one is doing LCAs to compare different products and must be chosen in a fair way. Any assumptions made at this stage, or at any other stage during the LCA, must be clearly noted. Another example is to perform an LCA of bananas that originate from two different countries. Is it less environmentally harmful for the supermarket (based in Sweden) to buy bananas from South Africa or Costa Rica? In this case, 1 kg of bananas from each country could be the functional unit. One would need to include not only the different distances needed to transport the bananas to Sweden but also the type of transport used, the fertilizers and pesticides used in the two countries, and other factors. 4.1.3 SCOPE One also needs to define the scope of the LCA, that is, where to place the system boundaries. Many LCAs consider only a part of the life cycle. For example, the owner of the supermarket that sells the bananas may only be interesting in knowing the environmental impacts up until the bananas are sold. This LCA is then a cradle to the gate LCA. The reason for the supermarket owner to omit

4 The LCA Methodology

405

the use and disposal stages could be that she has no control over these stages or that she has no information about these stages. The following boundaries must also be stipulated: • Geographical boundaries. If the LCA is being done for a site, for example, a local supermarket, then one should, as far as possible, use data that are relevant for that site. In contrast, if the LCA is for a region (e.g., Sweden or Europe), then data that are relevant for these regions are needed. • Time boundaries. It is very difficult to predict the environmental effects of emissions over longtime periods. For example, it is widely accepted that global warming leads to dramatic changes in weather patterns. However, less is known about the long-term effects of global warming. Long-term predictions are also made more difficult due to the continual improvement of technical systems, such as systems for waste treatment.

4.1.4 METHOD TO CALCULATE THE ENVIRONMENTAL IMPACTS The impact assessment model must be chosen. The impact categories differ between different models. The categories that are included in the international reference life-cycle data system (ILCD) for midpoint indicators [35] are given in Table 2. This model is recommended by the European Commission [36]. The same model must be used if one performs an LCA to compare different products or processes.

TABLE 2 Impact Categories That Are Included in From the ILCD Midpoint Model. Impact Category Resources used Land use Water resource depletion Mineral, fossil, and renewable resource depletion Emissions Climate change Ozone depletion Human toxicity, cancer effects Human toxicity, noncancer effects Particulate matter Ionizing radiation, human health Ionizing radiation, ecosystems Photochemical ozone formation Acidification Terrestrial eutrophication Freshwater eutrophication Marine eutrophication Freshwater ecotoxicity

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Life-Cycle Assessment and Sustainability Aspects of Food Waste

4.1.5 ALLOCATION Sometimes the environmental impact has to be allocated between different products or processes. Two examples when allocations of resources and emissions need to be considered are when 1. A single process yields many products 2. Waste treatment has many different types of input An example of the former is when determining the environmental impact of 1 kg of beef or 1 kg of beef waste. One of the processes is to farm the cows that provide the beef. Hence, to calculate the environmental impact of the beef, one needs to know the environmental impact of rearing the cow (including cow feed and emissions from the cow). However, the cow may also yield other products such as milk. The environmental impact should therefore be allocated between the beef and milk products. This can be done, for example, by dividing the total impacts based on the relative weights of beef and milk products obtained during the cow’s lifetime. It can also be based on the relative economic value of beef and milk. As illustrated in Fig. 4, anaerobic digestion (AD) is multifunctional, that is, it yields two products (biogas and digestate) and a service (waste management). AD also has multiple inputs (meat, vegetables, bread, manure, etc.). Because of this, there are two consequences regarding allocation of AD. The first is due to the multifunctionality. The resources consumed and emissions from the AD facility must be distributed among the biogas and digestate products and the waste management service. One needs to allocate the relative amounts of the emissions and resources consumed to each of the products (biogas and digestate) and the service (waste treatment). The second is due to the fact that there are multiple inputs to the AD process. One must allocate how much of the biogas, digestate, and service is due to each of the different feedstocks, for example, when determining the environmental impacts of treating 1 kg of vegetable waste using the AD process. As illustrated in Fig. 4, the vegetable waste is usually mixed with other types of biodegradable wastes before it is treated at the AD plant. Hence the environmental impacts of biogas, digestate, and the service from the AD plant are combined yields from all feedstocks. The question is how much of the combined environmental

FIG. 4 A simplified flowchart of an AD plant with different feedstocks.

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407

impacts can be allocated to each individual feedstock. One can use the methane production potential for the feedstock of interest to determine the amount of methane produced from it. Vegetable waste, for instance, has a methane yield ranging from 0.19 to 0.4 m3 CH4 kg
1 VS [37].

4.1.6 EXTENDING THE SYSTEM BOUNDARIES A way to improve the allocations is to extend the system boundaries (it can be decided to use this method in the goal and scope definition). For example, the biofuel and digestate that are produced in the AD plants shown in Fig. 4 could be used as fuel for transport and fertilizer, respectively. This means that one can avoid using other fuels for transport (e.g., fossil fuel) and other types of fertilizers (e.g., synthetic fertilizers). The system boundaries can be extended, as shown in Fig. 5, to include the avoided use of these substituted products, which is usually positive for the environment. These avoided environmental impacts are then subtracted from the total impacts of the system.

4.2 Inventory Analysis There are three steps in inventory analysis.

4.2.1 CONSTRUCT A DETAILED FLOW CHART The first step in the inventory analysis is to extend the simplified flowchart that may have been developed in the goal and scope definition into a detailed flowchart. All processes that have a nonnegligible environmental impact should be included in the detailed flowchart—that is, they should be included in the scope of the LCA. 4.2.2 COLLECT DATA FOR EACH PROCESS IN THE DETAILED FLOW CHART After developing the detailed flowchart, data of inputs and outputs for each process are gathered. That is, for each process, one obtains data on the natural

FIG. 5 Extending the boundaries of the system shown in Fig. 4 to include the fossil fuel and synthetic fertilizers that are substituted by the biofuel and digestate obtain from the AD.

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Life-Cycle Assessment and Sustainability Aspects of Food Waste

FIG. 6 Illustration of a process in the LCA flowchart showing the data that need to be collected.

resources used for the process, the emissions from that process, any products that may enter the process, and products that leave the process. This is illustrated in Fig. 6. One typically obtains this information from suppliers, from similar LCAs, or one can use data in standard LCA models. There can be many thousands of processes in the detailed flowchart, emphasizing the fact that detailed and complete LCAs can be very time consuming.

4.2.3 SCALE THE DATA TO THE FUNCTIONAL UNIT Once one has all of the inputs and outputs for each process, one scales these data to the functional unit (e.g., 1 kg of beef waste). Then, one sums over the natural resources and emissions from all processes in the flowchart to get the total resources used and emissions for the functional unit.

4.3 Impact Assessment In the impact assessment step, the environmental consequences (impacts) of the data quantified in the inventory analysis are calculated. This is to make the inventory results environmentally relevant and easier to understand and communicate. It also means that one can compare products or processes that use different types of resources or that have different types of emissions. To do this the units used in the inventory analysis (e.g., MJ of energy or kilograms of emissions) are changed to impact factors (e.g., kg CO2eq to describe global warming potential and kg P eq. to reveal freshwater eutrophication). As described earlier, there are several models to assess the environmental impact; one of which, shown in Table 2, is the ILCD midpoint model.

4.4 Interpretation In the fourth and final step of LCA, the results are analyzed, and conclusions are drawn. The results are usually also put into perspective. For example, the impact assessment may reveal that 1 kg of beef that is wasted at a supermarket has a global warming potential of 30 kg CO2eq. This may have very little, if any, meaning to the owner of the supermarket where the waste was generated. To report this number in a way that is meaningful to the owner, one may compare it to the global warming potential of 1 kg of another type of food waste. Hot spots (processes in the flowchart that have the largest environmental impacts) can also be identified, sensitivity analyses for data that are uncertain or that dominate the results, and conclusions can be determined. One can also group the results in sets, such as local, regional, and global impacts. For

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example, freshwater eutrophication is local (or regional) since it effects only the lakes that are sinks for the eutrophication emissions. In contrast, global warming is a global impact—the entire planet is affected by these emissions irrespective of where the emission occurs.

4.5 Simplified LCA This is an illustrative example of the calculation steps done in a typical LCA. The example involves a lot of simplifications and do not necessarily represent the reality. Consider that you have been assigned, as an LCA expert, to assess the environmental implication of a project that uses a new technique that aims to reduce on-site methane emissions of a composting plant, named “LowMethane” technology. Note that this technology does not exist and is used for illustrative purposes only.

4.5.1 THE GOAL AND SCOPE DEFINITION The goal of this LCA is to compare the current system used in the composting plant, referred as “baseline,” with the new LowMethane technology in terms of its environmental performance. The scope of the environmental impact is limited to the climate change impact category. This comparative study is expected to be used internally at the composting plant to support the decision of the implementation of the new technology and will not be disclosed to the public. The functional unit is 1 tonne of organic waste treated by each of the technologies. The system boundaries only include environmental impact due to the direct releases of greenhouse gases in the composting process, simplified as only carbon dioxide and methane emissions in this example. The resources used and emissions caused by upstream and downstream processes are not included in the LCA, since it is expected to be the same for both alternatives. The geographical scope of this study is the composting of organic waste in Sweden. 4.5.2 THE INVENTORY ANALYSIS In this simplified example the data related to the emissions of greenhouse gases for both scenarios were measured on-site and related to the functional unit (Table 3). TABLE 3 Comparative LCI Results for the Baseline and the LowMethane Technology per Tonne of Organic Waste Treated in the Composting Plant. Flow

Compartment

Unit

Baseline

LowMethane

Carbon dioxide

Air

kg

16

45

Methane

Air

kg

2

1.2

The emissions are illustrative and do not reflect the actual emissions of a composting plant.

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Life-Cycle Assessment and Sustainability Aspects of Food Waste

TABLE 4 Impact Factors for the Climate Change Impact Category. Substance

Compartment

Factor

unit

Carbon dioxide

Air

1

kg CO2eq/kg

Methane

Air

25

kg CO2eq/kg

4.5.3 THE IMPACT ASSESSMENT In this step the emissions of carbon dioxide and methane are translated into a common indicator, in this case using the climate change impact category. The characterization factors are detailed in Table 4 and use the ILCD 2011 midpoint method, released by the European Commission Joint Research Centre [38]. The calculation is as follows: Baseline 1 ½kg CO2 eq 25 ½kg CO2 eq + 2½kg CH4   ¼ 66 ½kg CO2 eq 16 ½kg CO2   ½kg CO2  ½kg CH4  LowMethane 45½kg CO2  

1½kg CO2 eq 25 ½kg CO2 eq + 1:2½kg CH4   ¼ 75 ½kg CO2 eq ½kg CO2  ½kg CH4 

4.5.4 THE INTERPRETATION The results show that although the LowMethane technology reduces considerably the emissions of on-site methane, it comes with a cost of a significant increase in the emissions of carbon dioxide. When accounting the amounts emitted and the impact factor for each substance, it can be concluded that the new project increases the impacts on the climate change category (75 kg CO2eq) in comparison with the baseline (66 kg CO2eq).

5 ENVIRONMENTAL PERSPECTIVES OF DIFFERENT WASTE TREATMENT METHODS Several researchers have studied the environmental impact of food and food waste. Some of these studies have focused on the relative impacts of different waste treatment methods. Prevention of food waste has been studied by several authors [39–46]. Many of these studies focused only on climate change and yielded results for reduced global warming potential (GWP) that ranged from 0.8 to 4.4 kg CO2eq/kg of food waste that was prevented. Most of these impacts are related to the processes that are upstream from the waste generation (food production, transport, etc.) with fewer impacts resulting from the waste treatment. The large divergence

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411

of the results is primarily due to differences in the way in which these upstream processes are modeled. An interesting effect of food waste prevention is called the rebound effect [46, 47]. This effect is seldom included in LCAs, although it could have a significant environmental impact. Minimization of food waste at households is directly related to reduction in the purchasing of unnecessary food. Since less food is purchased, households can spend their finances on other products. For example, they can increase their spending on textiles or use their private cars rather than public transport. This might lead to a decrease in the environmental saving associated with the prevention of food waste. Bernstad Saraiva Schott and Andersson [44] performed an LCA to compare the relative environmental impacts of prevention of food waste, anaerobic digestion (AD) of the food waste, and incineration of the waste. Their study was based on households in Southern Sweden, using typical compositions of household food waste in this region, and was limited to an analysis of the GWP. They found that preventing food waste could result in a reduction of 0.80–1.4 kg CO2eq/kg avoidable food waste. Although this result depends on the type of food waste (beef, vegetables, etc.), food waste minimization has a far larger environmental saving than treating the waste using AD or incineration (Table 5). The Waste and Resources Action Programme (WRAP) compared the environmental benefits of different waste treatments for a variety of streams, including food and garden waste [48]. The review for this stream was based on seven LCAs done between 2000 and 2009 and with six different geographical scopes, ranging from Australia to the United States and Norway. Hence, even though the

TABLE 5 A Summary of Results From Different Studies of Food Waste Prevention and Improved Waste Treatment. Waste Treatment or Prevention Method

Type of Food Assessed

Result

Unit

References

Prevention instead of AD or incineration

Mixed food waste


0.80 to
1.4

kg CO2eq/kg avoidable food waste

Bernstad and Andersson [44]

Convert surplus food to chutney instead of incineration

Sweet pepper


1.0

kg CO2eq/kg of food waste

Eriksson and Spa˚ngberg [23]

Remove packaging prior to AD to improve recycling efficiency

Mixed food waste


1.0

tonne CO2eq/ store/year

Brancoli et al. [49]

Feeding animals with surplus food instead of AD

Bread


1.5

tonne CO2eq/ store/year

Brancoli et al. [49]

Reducing storage temperature in supermarkets from 4°C to 2°C

Meat


12

tonne CO2eq/ store/year

Eriksson et al. [21]

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Life-Cycle Assessment and Sustainability Aspects of Food Waste

LCAs are based on old data, they provide a large geographical scope. The treatment methods that were compared for this waste stream were composting, AD, incineration, and landfill. Based on these seven LCAs, AD appears to be the preferred treatment method when considering GWP and depletion of natural resources. However, as noted by WRAP, only three of the seven studies considered AD, although all three of these studies concluded that it was the preferred treatment. Composting has the advantage that it can substitute mineral fertilizers, which are often rich in nitrogen and phosphorous. Composting is therefore the favored option when considering the eutrophication impact category. However, energy is not recovered when composting, and when comparing with methods that recover energy, it therefore does not compare well in the depletion of natural resources impact category. The extent of the benefits that are obtained from methods that recover energy depends on the energy mix that is assumed in the LCA (which differs between the countries studied in the seven articles), with larger benefits being obtained when energy from fossil fuel is substituted by the biofuel produced from the waste. Brancoli et al. [49] used LCA to compare different waste treatment methods for supermarket food waste. Their calculations were based on the meat (beef, chicken, and pork), bread, fruit, and vegetable fractions, which is 50% of the total food waste at the supermarket. Similarly to other studies [46], Brancoli et al. [49] showed that packaging does not substantially contribute to the environmental impact of food waste if one simply includes the production of the packaging. However, the packaging can also hinder efficient treatment of the waste, which can increase the environmental burden of the treatment. For example, the food waste from the supermarket studied by Brancoli et al. [49] is treated using AD, which is typical for Sweden. In this process the packaged food waste is sent to the treatment facilities where the food is pressed from the packaging before being transferred to the bioreactor. Up to 44% of the initial mass that enters the facilities, including food, remains with the packaging [49]. This has several disadvantages. First a large amount of food is not used for AD. Second the packaging is contaminated with food and is therefore sent to incineration instead of recycling. Third the packaging fraction is wet, which is not optimal for incineration. Brancoli et al. [49] therefore compared the present AD process with one where the packaging was separated from the food waste before being sent to the treatment facilities. In this scenario all the food would be transferred to the bioreactor, and the packaging could be recycled. This reduced the supermarket’s contribution to GWP by over 1 tonne CO2eq per year. The study showed that the supermarket could also reduce its contribution to GWP by over 1.5 tonne CO2eq per year if the bread waste was used for animal feed instead of AD. Eriksson et al. [21] used a similar approach to compare the global warming potential from different ways of treating different types of surplus food from supermarkets. These ways were landfill, incineration, composting, anaerobic digestion, and donation to cover several steps in the waste hierarchy. Bread

6 Conclusions and Perspectives

413

was together with meat identified as the product with the greatest potential for reducing greenhouse gas emissions by improving food waste management, and every kilogram of surplus bread that was donated resulted in 2.7 kg less CO2eq emission than when treating it using landfill. Incineration and anaerobic digestion had a similar impact as donation, but since the study only considered the environmental impacts, the social values of donating surplus food was not revealed in the comparison. Also, in Eriksson and Spa˚ngberg [23], different ways of handling surplus fruits and vegetables were assessed to calculate the primary energy use and global warming potential. Incineration and anaerobic digestion were compared with donations to charity and conversion of the surplus food to new food products (i.e., chutney). The study found that the energy recovery alternatives (incineration and anaerobic digestion) could reduce the global warming potential by 0.04 to
0.23 kg CO2eq/kg of food waste and reuse alternatives (conversion and donation) were in the range
0.35 to
0.98 kg CO2eq/kg of food waste. The corresponding range for primary energy use was 1.2 to
1.2 MJ/kg of food waste for energy recovery and
5.1 to
16 MJ/kg of food waste for the reuse options. Eriksson et al. [45] assessed the potential to reduce food waste in supermarkets by reducing the storage temperature. This included calculations of the reduction in greenhouse gas emissions and in monetary costs. The most important finding was that there are significant opportunities for reducing food waste by decreasing the storage temperature. Waste reduction increased with decreased temperature, with the maximum reduction (16%–30%) for each department (cheese, dairy, deli, and meat) being found at the lowest storage temperature tested (2°C). However, since lower storage temperature requires higher energy input, electricity consumption increased for all departments with decreased storage temperature. It was the largest for the dairy department, due to the large volumes of dairy products that need cooling. The net effect was calculated by subtracting the costs and impacts of the increased energy requirement for cooling from the decreased costs and impacts of food waste. The highest cost efficiency was found for the meat department (Fig. 7), where a reduction from 4°C to 2°C gave a net savings potential of 56,000 SEK/store/ year, (equivalent to 5.6000 USD/store/year) and 12 tonne CO2eq/store/year. In the other departments the net savings were lower. This led to the conclusion that reduced temperatures for products with low turnover and high relative waste would give the highest cost efficiency, although the largest waste reduction potential in terms of mass would be obtained for products with high turnover.

6 CONCLUSIONS AND PERSPECTIVES Managing food surplus and food waste affects all three aspects of sustainable development—social, economic, and the environment. In fact, food surplus and waste relate directly with four of the United Nations’ 17 Sustainable Development Goals and indirectly to five of the remaining goals. With the projected

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Life-Cycle Assessment and Sustainability Aspects of Food Waste

GWP for waste treatment (kg CO2e/kg food waste)

2

1

0

Landfill Incineration

–1

Composting Anaerobic digestion

–2

Animal feed Donation

–3

Prevention

–4

–5

FIG. 7 A summary of the results from different methods to treat meat waste assessed in Eriksson et al. [21, 40]. All units are displayed in kg CO2eq/kg of food waste, and negative values indicate a reduction of emissions.

increases in global population and urbanization and the related increase in food demand, the proper management of food will become even more important. Donation is an example where proper management of food surplus affects the social aspects of sustainable development. Donation improves the living conditions of people who otherwise do not have access to food of high quality. The economic aspects of sustainable development can be measured in terms of financial costs and gains for the food producers, sellers, and consumers. As discussed in detail in this chapter, the environmental impact can be estimated using LCA. Examples of LCAs that reveal the relative impacts of different waste treatment methods are also given. Results from LCAs should be used when selecting preferred waste treatment schemes. Future research and development will improve methods for managing food surplus and food waste and develop new methods. For example, proper packaging of food is required to increase the shelf life of food products, thereby potentially decreasing waste. However, the packaging material also bears an environmental burden and must be designed to minimize this burden by, for example, encouraging recycling of the packaging. Similarly, methods to improve the use of food waste in a circular economy must be developed. This can be achieved by using the food substrate to produce high-value products such as protein-rich food or polymers.

ACKNOWLEDGMENTS The authors are grateful for financial support from Sparbanksstiftelsen Sjuh€arad and Sjuh€arad Association of Local Authorities.

References

415

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Index Note: Page numbers followed by f indicate figures and t indicate tables.

A Aceticlastic methanogenesis, 165, 166f Acetogenesis, 165, 166f, 174, 174t Activated oyster shell (AOS), 351 Adsorbents, 156, 156f Adsorption, 219 Aerobic composting process, of organic materials, 138, 138f Agitation, 362–363 Agroindustrial wastes, 351 Alcohol production, from VFAs, 218 Alkaline materials, 141–145, 153–154 Alkyl polyglucosides (APGs), 348–349, 351 Ammonia (NH3), 141–145, 149–150, 152–154, 155f, 177 Ammonia-oxidizing archaea (AOA), 148–149 Ammonia-oxidizing bacteria (AOB), 148–149 Ammonium, 6, 148–149 Ammonium nitrogen, 25, 26–28t Amylases, 261–262 Anaerobic codigestion (AcoD), 176 Anaerobic digestion (AD), of food waste, 6–7, 21–22, 163–164, 257–260, 280, 363–364, 364f, 379, 406, 406f, 411–412 advantages, 165–166 ammonia inhibition, 177 anaerobic codigestion (AcoD), 176 biochemical parameters and synergistic effects, 167–176, 168t bioelectrochemical system (BES), 182–184 gas environment, 174–175 inoculum/microbes, 170–172, 172f integrated treatment, zero waste discharge, 191–192, 191f journal publications on, 164–165, 164f LCFAs, inhibitory effect of, 177–178 pH/alkalinity, 173 phase-separated digesters, 181–182, 182t, 183f pretreatment, 175–176 principles of, 165–167, 166f resource recovery, 164–165, 185–190

sodium, inhibition efficiency of, 178–179, 179f substrate composition, 167–170 sulfide inhibition, 179–180 technical and economic challenges, 164–165 Anecic earthworms, 245 Animal By-Products Regulation (ABPR), 67 Animal feed, from food waste, 125–129 bakery waste, 321 brewery waste, 320 cabbage waste, 321 cattle feed, 318–320 challenges, 5, 128–129 chemical/physical processing, 126 contamination risks, 5, 129 cooked animal food waste, 307–308 dairy products, 307–308 direct conversion, 313–314 duck feed, 321 EU project, 129 fish and seafood, 307–308 fish feed, 320 greenhouse gas emissions, 305–306 indirect conversion, 314–316 landfill, 305–306 meat products, 307–308 municipal solid waste, 305–306 nutritional value, 308 pet feed, 320–321 plant-derived food waste, 306–307 poultry feed, 321 processing methods, 5, 308–313, 314t regulatory framework, 126–128 swine feed, 321–322 Animal protein synthesis, 292 Artificial food waste, 164–165 Aspergillus niger, 283 Astaxanthin, 247 A2UFood project, 122–123 Avoidable food waste, 43–44 definition, 108t global warming impact of, 110 prevention of, 113–120

419

420

Index

B Bags/liners, for food waste collection, 79–80, 79f Bill Emerson Good Samaritan Act, 124 Biobased materials biopolymers, 288–292 soil amendment materials and green composites, 287–288 Biochar, 8, 156, 336–337, 338f, 352, 354t Biodiesel, 217 Biodrying (bioevaporation) aeration and agitation, 362–363 anaerobic digestion, 357–358 bulking agents, 362 composting, 358 convective evaporation, 358 moisture content and FAS, 362 principles, 358–359, 359f process and reactor, 359–361, 361f solid wastes, 358 thermal drying, 357–358 waste matrix, moisture content of, 358 WTE conversion processes, 357–358 Bioelectrochemical system (BES), 182–184 Bioenergy, 217–218 Biofuels, 164–165, 205 ethanol and butanol, liquid biofuel production, 296–298 methane and hydrogen, gaseous biofuel production, 294–296 Biohythane, 188 Bio Intelligence Service, 45–46 Biological nutrient removal (BNR), 363–364 Biooil, 8, 335–336 Bioplastics, 216 Biopolymers animal protein synthesis, 292 pectin extraction, 291–292 PHA production via pretreatment-aided microbial fermentation, 289–290 PHA synthesis, multistage valorization of FW for, 290–291 Biopyrolytic oil, 8 Biorefinery, 7, 205 Biowaste, 44, 64–65, 83, 84f, 349 Black soldier fly larvae (BSFL), 238–240, 239f Boroume, 122 Bulk chemicals citric acid (CA), bioconversion of citrus FW to, 283–284 succinic acid, fermentation of FW to, 285 Bulk density, 17, 140 Bulking agents, 362

Bulking containers, for food waste collection, 77 Butanol, 296–298

C Calcium (Ca) concentrations, of food waste, 29–32, 30–31t Calcium oxide (CaO), 351 Carbohydrates, 32–35, 33–34t, 167–168 Carbon-based adsorbent gasification, 352–353 hydrothermal carbonization, 353–354 pyrolysis, 352 Carbon dioxide (CO2), 174–175, 410 Carbon-to-nitrogen (C/N) ratio, 5–6, 17, 25–29, 26–28t, 140–142, 150, 177 Carboxylic acids, 175 Cattle feed, 318–320 Cellulases, 263–265 Centrifugation, 219 Chemical extraction, of VFAs, 219–220, 220t Chemical oxygen demand (COD), 22–25, 23–24t Chitosan, 349–350 Chromatographic analysis, of VFAs, 225 Circular Economy Package (CEP), 4, 111–112, 380–381 Citric acid (CA), 283–284 Citrus peel waste (CPW), 282–283, 296 Clostridium beijerinckii, 297–298 Coal fly ash (CFA), 143–145, 144f Cockroaches (Blatta orientalis) application, in food waste treatment, 250 life cycle of, 247 nutritional contents of, 247–249 pathogenic bacteria, 246 pharmaceutical value of, 250 protein resource, 246 Codigestion, FW and sludge challenges and opportunities, 366 ratios, importance of, 364–366 Cogasification, 332–333 Collagen, 350–351 Collection, of food waste, 61, 66 bags/liners, 79–80, 79f bulking containers, 77 capture rate, 66 collection frequency, 85–87 combination of methods, 68, 70–71 communication plan and awareness raising activities, 92–96 diversion rate, 66

Index door-to-door system, 3–4, 52–54, 68–70, 70–71f drop-off/bring-in system, 68–70, 71–72f household-scale drying systems, 78–79, 78f indoor containers, 73–74, 73f investment cost categories, 87–88 kerbside system, 68–70, 70f, 72f kitchen grinders, 78 monitoring and evaluation, 89–92 multistream collection, 67–68 operation and maintenance cost categories, 88–89 outdoor containers, 73–77, 74f, 75t, 76f participation rate, 66 separate collection scheme (see Separate food waste collection system) single stream collection, 67–68 staff/personnel, 83–85, 85f vacuum collection systems, 77–78 vehicles, 80–83, 83–84f Commercial and industrial (C&I) food waste, 138 Communal collection bins, 75 Communication and awareness raising activities, 92–93 advertising, 94, 95f community engagement, 93–94 direct information activities, 93, 93f economic incentives, 94–96 on line, 94 Compostable bags, for food waste collection, 79–80, 79f Composting, 412 acidity control, 6, 141–148 bulk density, 140 carbon-to-nitrogen (C/N) ratio, 5–6, 140 curing and maturation phase, 138–139, 139f definition, 138 food waste properties, 140–142, 141t mesophilic/moderate-temperature phase, 138–139, 139f moisture content, 5–6, 140 nitrogen loss and its control measures, 6, 148–156 objectives of, 139–140 organic materials, aerobic composting process of, 138, 138f oxygen availability, 5–6, 140 pH range, 140 temperature, 140 thermophilic/high-temperature phase, 5–6, 138–139, 139f

421

Compound annual growth rate (CAGR), 265 Contamination risks, animal feed from food waste, 129 Continuously stirred tank reactors (CSTR), 295 Control of Livestock and Feed Act, 128 Copyrolysis, 334–335 Courtauld Commitment, 383–384 Crickets for food waste reduction, 251 nutrient content, 251–252 Cubic regression model, 179f

D Dehydration, 309–310 Devolved administrations (DAs), 385 Dipotassium hydrogen phosphate (K2HPO4), 145 Dissolved H2 (D-H2), 174–175 Dissolved sulfide (DS), 180 Domestic food waste disposal rate, 138 moisture content, 141 Domestic wastewater, comanagement of external carbon sources, enhance BNR, 367 FW and sludge, codigestion of, 364–366 wastewater and FW, codigestion of, 367–368 Door-to-door food waste collection system, 3–4, 52–54, 68–70, 70f Dried distiller’s grains with solubles (DDGS), 402 Drop-off collection system, 68–70, 71–72f Duck feed, 321

E Eco-feed, 128 Electrical conductivity (EC), 22, 23–24t, 145, 146f, 152–153, 154f, 156, 156f Electrodialysis (ED), 191–192, 191f, 224 Electrodialysis with bipolar membrane (EDBM), 191–192 Elemental analysis, of food waste, 29–32, 30–31t, 58–61 Elemental composition, of food waste, 169–170, 170t Endogeic earthworms, 245 Enzyme loading, 269 Epigeic earthworms, 245 Espigoladors, 119 Essential amino acids (EAA), 247

422

Index

Essential oils (EO), 285–286 Ethanol, 296–298 European Commission (EC), 111, 127 European Economic Area (EEA), 118–119 European Food Banks Federation (FEBA), 121 European Former Foodstuff Processors Association (EFFPA), 127–128 European Regional Development Fund, 122–123 European Union (EU), food waste animal feed, regulatory framework, 126–128 Circular Economy Package (CEP), 111–112 definition, 45–46 generation of, 49–50, 50f REFRESH project, 117–118 External carbon sources, enhance BNR direct use of FW, 367 FW-derived VFAs, 367 Extractive/diffusive membrane processes, for VFA recovery electrodialysis, 224 forward osmosis, 225 membrane contactors, 224–225 pervaporation, 223–224

F FareShare, 120, 122 Fat and oil, in food waste, 61 Feed conversion ratio (FCR), 237, 240 Fermented food waste (FFW), 290 Fertilizer, 128, 403–404, 407 Fish feed, from food waste, 5, 126 FLAW4LIFE project, 4–5, 119 Flocculation, 310 Fluidized bed gasification technology, 328 Fly larvae, 238–240, 239f Food and Agriculture Organization (FAO), 1, 45–46, 107, 163–164, 247, 280, 349, 395–396 Food banks, 120–122 Food donation, 4–5 barriers, 120, 123–125 Boroume, in Greece, 122 EU-funded projects, 122–123 FareShare, United Kingdom, 122 food banks, 120–122 gleaning, 120–121 operational issues, 123t, 125 regulation issues, 123t, 124 Food insecurity, 108–110 Food loss in America, 50–52 in Asia, 50

causes of, 47, 48t by commodity, 47–49, 49f cost of, 12 definition, 12, 45–46, 108t economic impacts, 108 environmental impact of, 110 by FSC stage and geographic region, 12–14, 13t, 14f, 47, 47f quantities of, 14, 15–16t social impact, 108–110 Food Losses and Food Waste (FLW), 381 Food poverty, 43–44 Food service sector, 117 Food supply chain (FSC), 1, 44, 110–111, 280–281 European Union Circular Economy Package (CEP), 111–112 food wastage, by stage and geographic region, 12–14, 13t, 14f, 47, 47f, 107–108, 109f, 115 food waste hierarchy, 112–115, 114f prevention, of food surplus and waste, 115–120 redistribution, of food surplus (see Redistribution, of food surplus) Sustainable Development Goals (SDGs) Target 12.3, 111 Food surplus definition, 108t, 113 level of, 113 management framework for, 113, 114f prevention of, 113–120 redistribution for human consumption, 4–5, 120–125 Food waste (FW), 1, 163–164 accounting, 3, 44 in America, 50–52, 51f anaerobic digestion of (see Anaerobic digestion (AD), of food waste) animal feed production (see Animal feed, from food waste) in Asia, 50, 51f bromatological properties, 61–63, 62–63t carbohydrate contents of, 32–35, 33–34t categorization system, for compositional analysis of, 52, 53t causes of, 47, 48t, 115–116 chemical properties, 22–25, 23–24t, 54–58, 55–57t collection schemes (see Collection, of food waste) commercial and industrial (C&I) food waste disposal rate, 138

Index by commodity, 47–49, 49f composition, 206 composting (see Composting) definition, 12, 45–46, 108t, 113 domestic food waste disposal rate, 138 economic impacts, 108 economic implications, 43–44 elemental composition and light metal ions, 29–32, 30–31t elemental properties, 58–61, 59–60t environmental impact of, 110 environmental implications, 43–44 in European Union (EU), 49–50, 50f as feedstock, for industrial applications, 16 by FSC stage and geographic region, 12–14, 13t, 14f, 47, 47f, 107–108, 109f global scenario, 137–138 impacts, cost estimates of, 107 lipid contents of, 32–35, 33–34t management framework for, 113, 114f moisture content, TS and VS contents of, 17–22, 18–21t monetary value of, 12, 137 municipal solid waste (MSW) production, 138 National Waste Prevention Programs, 111 nutrient properties, 25–29, 26–28t per capita waste generation, 137 physical properties, 52–54 prevention of, 4–5, 113–120 protein content of, 32–35, 33–34t quantities of, 14, 15–16t recycling, animal and fish feed, 125–129 social impact, 108–110 sorting, 3–4, 52 as substrate, 16 Waste Framework Directive (2008/98/EC), 111 Food waste policy adequate storage and processing facilities, lack of, 378 anaerobic digestion (AD), 379 animal feeds, 378–379 Australia, 391–392 biomethane, 379–380 Canada, 391 Denmark, 387–388 developed economies, 378 edible food, 378 European perspectives, 380–389 France, 386–387 industrial food waste, 378–379

423

inedible food waste, 378 in-vessel composting (IVC) systems, 379 Italy, 388–389 perspectives, 392 prevention, 379 renewable energy uses, 379–380 UK Food Waste Policy Development, 381–386 USA State and Local Governments, 390–391 US Federal Government, 389–390 Food Waste Recycling Law. See Promotion of Utilization of Recyclable Food Waste Act Forward osmosis, 225 Free air space (FAS), 140, 361–362 Freeze-drying method, 311 Fruit and vegetable wastes (FVW), 281–282, 289 Fund for European Aid to the Most Deprived, 124 FUSIONS project, 45–46, 49, 129–130

G Gas chromatography (GC)-based analysis, of VFAs, 225 Gasification, 7–8, 352–353 Gas production, anaerobic digestion, 174–175 General Food Law (EU Regulation 178/2002), 124 Generation, of food waste, 1 in America, 50–52, 51f in Asia, 50, 51f bromatological properties, 3, 61–63, 62–63t chemical properties, 54–58, 55–57t economic implications, 3 elemental properties, 3, 58–61, 59–60t environmental implications, 3 in European Union (EU), 49–50, 50f feedstocks and high-value product conversions, 282 per capita waste generation, 137 physical properties, 3–4, 52–54 problem of, 280 utilization, biobased conversions, 280–282 Gibbs free energy, 174–175, 180 Gleaning, 120–121 Global warming potential (GWP), 43–44, 410–413 Green composites, 287–288 Greenhouse gas (GHG) emission, 3, 43–44, 46–47 Green waste collection scheme, 66–68

424

Index

H Heartside Gleaning Initiative, 120–121 Heavy metals, 58–61 High-capacity vehicle, for food waste collection, 83, 83f High-performance liquid chromatography (HPLC), 225 High-value products, recovery of animal FW, 349–351 calcium-based adsorbent, 351 carbon-based adsorbent, 351–354 microwave-assisted thermochemical conversion, 355 vegetable FW, 347–349 Homoacetogenesis, 165 Hospitality and Food Service Agreement (HaFSA), 383–384 Housefly larvae biodegradation, waste types, 241–242, 243t feed source, 242–244 food production, long-term missions, 241 lighting requirement, absence of, 241 maggots, 241 metabolites, 241 organic waste, fly biomass, 241–242, 242t reproduction, high rate of, 241 waste reduction/bioconversion processes, 240 Household waste drying system, 78–79, 78f Hydraulic retention time (HRT), 210–211 Hydrogen (H2), 164–165, 167–168, 174–175, 184–188, 187t, 294–296 Hydrogenotrophic methanogenesis, 165, 166f Hydrogen sulfide (H2S), 180 Hydrolytic enzymes, food waste treatment amylases, 261–262 application of, 262, 262t biofuels and sustainable chemicals, 258 cellulases and xylanases, 263–265 characteristics and significance, 258 conventional FW management methods, 259–266 enzyme loading, 269 food waste production, world market, 258 inducers and inhibitors, 271 lipases, 265–266 pH, 270 proteases, 265 solid-liquid ratio, 270–271

solid/submerged state fermentation strategy, 271–272 temperature, 269–270 Hydrothermal carbonization (HTC), 352–354 Hydroxyapatite, 351 Hythane, 188, 189t

I Imperfect fruits and vegetables, markets for, 4–5, 118–120, 119f Incineration, 205–206, 257–258 Industrial Symbiosis, 4 Inedible (unavoidable) food waste, 108t, 378 Inoculum/microbes, anaerobic digestion, 170–172, 172f Inoculum to substrate (I/S) ratio, 172 Insect and worm farming biological waste, 237 cockroaches (Blatta orientalis), 236–237, 246–250 crickets, 251 earthworms (Metaphire guillelmi), 244–246 feedstocks, 237 fly larvae, 238–244 food conversion ratios, 236–237 food waste utilization, 235–236 house cricket (Acheta domesticus), 237 houseflies (Musca domestica L.) (see Housefly larvae) organic wastes, 236 perspectives, 252 process automation, 252 vermicompost, 236 In situ product recovery (ISPR) techniques, 8 Intergovernmental Panel on Climate Change (IPCC), 395 International reference life-cycle data system (ILCD) for midpoint indicators, 405, 405t

K Kerbside collection system, 68–70, 70f, 72f, 74, 74f, 75t Kitchen caddies, 73–74, 73f Kitchen grinders, 78

L Lactic acid, 147, 348–349 Life-cycle assessment (LCA) allocation, 406–407 anaerobic digestion (AD) plants, 402 biotreatment, 402 circular economy, 399, 403 combustion, 402–403

Index composting, 402 dried distiller’s grains with solubles (DDGS), 402 economic costs, of food waste, 396 environmental impacts, 405 environmental perspectives, waste treatment methods, 410–413 food donation, 401 food surplus and food waste management, 399–403, 400f food transport and package, 396 food waste hierarchy, 397–399, 399f functional unit, 404 fungi, food waste, 403 Fusions definition, 401–402 geographical boundaries, 405 impact assessment, 408, 410 interpretation, 408–409 inventory analysis detailed flow chart, 407–408 functional unit, 408 municipal solid waste, 396 perspectives, 413–414 preferred waste treatment methods, 398–399 procedure, 403–404, 404f redistribution scheme, 401 simplified LCA goal and scope definition, 409 inventory analysis, 409 LowMethane technology, 409t, 410 sustainable development goals, 397–399, 397–398t system boundaries, 407 time boundaries, 405 LIFE Drywaste system, 78–79, 78f Lime, 143–145, 144f, 152–155 Lipases, 265–266 Lipid contents, of food waste, 32–35, 33–34t Liquid feeding, 312–313, 313f Long-chain fatty acids (LCFA), 169, 177–178 LOOFEN house dryer, 78–79, 78f Lower heating values (LHVs), 339, 339t

M Macronutrients, 169–170 Maggots, 241 Magnesium (Mg) concentrations, of food waste, 29–32, 30–31t Magnesium oxide (MgO), 145 Maleic anhydride (MA), 288 Malnutrition, 108–110 Management and treatment technologies, food waste, 2f

425

anaerobic digestion (AD) (see Anaerobic digestion (AD), of food waste) animal feed production (see Animal feed, from food waste) collection schemes (see Collection, of food waste) composting (see Composting) gasification, 7–8 landfilling, 2, 205–206 microbial fermentation, 7–8 political commitment, 4 pyrolysis, 7–8 volatile fatty acids (VFAs) (see Volatile fatty acids (VFAs)) waste prevention, 4–5 Mandatory Food Waste Act, 128 Marine processing wastes, 350 Markets, for imperfect fruits and vegetables, 118–120, 119f Mechanical biological treatment (MBT) plants, 58–61 Membrane contactors, 224–225 Membrane fouling, 223 Methane (CH4), 164–165, 167–169, 169t, 185, 186t, 188, 294–296, 402–403, 406–407, 409 Methanogenesis, 165, 166f, 169–170, 171t, 174, 174t, 179–180 Michaelis constants, 270–271 Microbial electrolysis cell (MEC), 183–184 Microbial electrosynthesis, 191–192 Microbial fermentation, 7–8, 289–290 Microbial fuel cell (MFC), 183–184 Microbial inoculation, 145–148 Microfiltration, 220–222 Micronutrients, 29–32, 30–31t, 35, 169–170, 364–366 Microwave-assisted thermochemical conversion biodiesel production, catalyzation for, 355 extraction of molecules, 355 pyrolysis, 355 Microwave drying, 312 Mineral salt medium (MSM), 289–290 MixAlco process, 218 Mixed culture fermentation (MCF), 207 Mixed food waste, 58–61 Municipal solid waste (MSW), 3, 12, 138, 212–213

N Nanofiltration, 221t, 222–223 National Research Council (NRC), 309–310

426

Index

National Resources Defense Council (NRDC), 118 National Waste Prevention Programs, 111 Nitrification, 148–149, 148f Nitrogen loss, composting process, 6, 148–156 adsorbents, use of, 156, 156f aeration rate, 150 carbon-to-nitrogen (C/N) ratio, 150 NH3 volatilization, 149 nitrogen transformation, 148–149, 148f struvite precipitation, 150–152 temperature and pH, 149 use of lime to reduce salinity, in struvite-based composting, 152–155 Nonbiodegradable materials, 3–4 Nutrients, 169–170, 171t, 178–179, 402 Nutritional loss, 108–110

O Organic fraction of municipal solid waste (OFMSW), 17–21, 18–21t, 141, 358, 364–366, 368 Organic loading rate (OLR), 211–212 Organic materials, aerobic composting process, 138, 138f Organic soil amendment (OSA), 287–288 Organic waste, 1, 12 anaerobic digestion, 165–166, 172, 259–260 biconversion, 237 composting of, 308 feed source, insects, 236 reduction, 236 solid particles, 362 Osmosis, 310 Outdoor containers, for food waste collection, 73–77, 74f, 75t, 76f Overground/surface communal collection bins, 75 Oxidation-reduction potential (ORP), 212 Oxygen, 140, 212

P Packaging waste, 12 Paper bag, 79–80, 79f Pay as you throw (PAYT) systems, 94 Pectin extraction, 291–292 Pervaporation, 223–224 Pet feed, 320–321 pH value, 270 anaerobic digestion, 173, 173f composting, 140, 145, 146f, 153–154, 154f, 156, 156f

of food waste, 22, 23–24t, 54–58, 141–142 Phytochemicals, 348 Plant-derived food waste, 306–307 Pneumatic waste collection systems, 77–78 Polyhydroxyalkanoates (PHAs), 216 production via pretreatment-aided microbial fermentation, 289–290 synthesis, multistage valorization of FW for, 290–291 Polylactide (PLA), 288 Postharvest grain loss, cost of, 108 Potentially avoidable waste, 108t Poultry feed, 321 Pressure-driven membrane processes, for VFA recovery, 221t membrane fouling, principle and control strategies of, 223 microfiltration, 220–222 nanofiltration, 222–223 reverse osmosis, 222–223 ultrafiltration, 220–222 Pretreatment in AD of food waste, 175–176 citrus peel waste (CPW), 283, 296 Prohibition of Waste Emission law, 128 Promotion of Utilization of Recyclable Food Waste Act, 128 Proteases, 265 Protein hydrolysates, 350 Proximate analysis, 17–22 Putrescible waste, 12 Pyrolysis and gasification, of food waste, 7–8, 352 biochar, 336–337, 338f bio-oil, 335–336 copyrolysis, 334–335 disposal of FW, 326 moisture content, effect of, 331–333, 332f, 333t organic wastes, at landfills, 325–326 perspectives, 340 principles of, 327 reactors, 328–330 recycling energy, in biomass, 326 rotary kiln technology, 328–330, 329f syngas characteristics, 337–339 temperature, effect of, 333–334 thermochemical method, 331

R Recovery and purification, of VFAs, 218 adsorption, 219 centrifugation, 219 chemical extraction, 219–220, 220t

Index extractive/diffusive membrane processes, 223–225 goals for, 218 pressure-driven membrane processes, 220–223, 221t Recycling, food waste, 125–129, 381, 388, 402 Recycling loops, 128 Redistribution, of food surplus, 120 barriers, 120, 123–125 Boroume, in Greece, 122 charities and nonprofit organizations, 4–5 EU-funded projects, 122–123 FareShare, United Kingdom, 120, 122 food banks, 120–122 gleaning, 120–121 operational issues, 123t, 125 regulation issues, 123t, 124 REFRESH project, 117–118, 129–130 Refuse-derived fuel (RDF), 346, 358–359 Residual waste, 96 Resource recovery, from AD of food waste, 164–165 hydrogen (H2), 185–188, 187t hythane, 188, 189t methane (CH4), 185, 186t volatile fatty acids (VFAs), 188–190, 190t, 207–215 Retail (and wholesales) sector, 116–117 Reverse osmosis, 221t, 222–223

S Sampling approach, food waste bromatological properties, 61–63, 62–63t chemical characteristics, 54–58, 55–57t elemental properties, 58–61, 59–60t Save the Food campaign, of NRDC, 118 Second opportunity restaurant, 122–123 Seed microbe, anaerobic digestion, 172 Semiunderground collection bins, 75–76 Separate food waste collection system, 4, 9, 64–66, 65f, 70–71 area characteristics, 4, 64 collection frequency, 87 existing/future treatment facilities, type and capacity of, 4, 64 food waste availability and expected yields, 4, 64 green waste collection scheme, 66–68 heavy metal concentrations, 58–61 investment cost categories, 87–88 large producers, incorporation of, 71–73 legislation, 4, 64 mixed MSW, mechanical separation of, 3–4

427

operation and maintenance cost categories, 88–89 political and social acceptability, 4, 65 single stream collection, 67–68 source separation systems, 3–4 underground bins, for municipal waste collection, 75–76, 76f Separate hydrolysis fermentation (SHF), 285 Silage, 312 Simultaneous saccharification and fermentation (SSF), 285, 297 Single cell protein (SCP) production, 315 Single/multifamily residences, door-to-door collection system, 70, 71f Single-phase AD system, 181, 183f Sliding roof containers, 77 Small-capacity vehicles, for food waste collection, 83, 83f Smart Cara CS10 house dryer, 78–79, 78f Sodium (Na), 29–32, 30–31t, 178–179, 179f Sodium acetate, 145 Sodium lauryl sulfate (SLS), 348–349 Solar drying, 310 Solid-recovered fuel (SRF), 346 Solid-state fermentation (SSF), 271–272 Soluble COD (SCOD), 22–25, 23–24t Source-segregated food waste (SSFW), 17–21, 18–21t Soybean meal (SBM), 244 Specialty/fine chemicals, food waste biosurfactant production, FW as feedstock, 286–287 essential oils, production of, 285–286 Spent coffee grounds (SCG), 281–282, 287–289 Spray drying method, 311, 311f Standard hydrogen electrode (SHE), 183–184 Starch-based bags, 79–80, 79f Stationary vacuum systems, 77 Struvite crystals, food waste composting, 152–155 chemical and physical properties of, 150, 151t precipitation, 150–152 Submerged fermentation (SmF), 272 Succinic acid (SA), 285, 348–349 Sulfate-reducing bacteria (SRB), 179–180 Sulfide, 179–180 Sulfur (S) content, of food waste, 29, 30–31t, 58 Sustainability and circularity, of FSC, 110–111 European Union Circular Economy Package (CEP), 111–112 food waste hierarchy, 112–115, 114f

428

Index

Sustainability and circularity, of FSC (Continued) Sustainable Development Goals (SDGs) Target 12.3, 111 Sustainable Development Goals (SDGs) Target 12.3, 3, 44, 111 Swine feed, 321–322

T Thermochemical treatment strategy, 258 Thermoselect process, 328–330, 329f Think.Eat.Save website, 118 Three-phase AD systems, 181–182, 183f Total amino acid (TAA), 247 Total COD (TCOD), 22–25, 23–24t Total Kjeldahl nitrogen (TKN), 25, 26–28t, 54–58 Total organic carbon (TOC), 25, 26–28t Total phosphorus (TP), 25, 26–28t, 54–58 Total potassium (TK), 25, 26–28t Total solids (TS), 17–21, 18–21t, 54–58, 206 Trace elements, 169 Treatment, of food waste, 2f anaerobic digestion (AD) (see Anaerobic digestion (AD), of food waste) animal feed (see Animal feed, from food waste) biodegradable FW debris, 345–346 biodrying (bioevaporation), 346, 357–363, 360t biorefinery products, 346 composting (see Composting) domestic wastewater, comanagement of, 363–368 gasification, 7–8 high-value products, recovery of, 347–355 microbial fermentation, 7–8 municipal solid waste (MSW), 345–346 pyrolysis, 7–8 recycling, 346 types and valorization routes, 346, 347f volatile fatty acids (VFAs) (see Volatile fatty acids (VFAs)) wet mass, 345–346 Tunnel drying, 310, 311f Two-phase AD systems, 181–182, 183f Two-stage fixed bed gasification technology, 328–330

U Ultrafiltration, 220–222, 221t Underground collection bins, 75–76, 76f

Unfermented (UFW) food waste, 290 United Nations Environment Programme (UNEP), 118 Upflow anaerobic sludge blanket (UASB) reactor, 296 Urban Innovative Actions Initiative, 122–123 US Environmental Protection Agency (USEPA), 45–46

V Vacuum collection systems, 77–78 Vacuum drying, 312 Valorization, food waste (FW), 95f, 112, 205–206, 258 bioadhesives, 293 biobased materials, 287–293, 288f biofuel production, 293–298, 294f biopolymers, 288–292 bulk chemicals, 283–285, 284f food chain supply wastes, 279 food demand, 279 generation, food waste (FW), 280–282 specialty/fine chemicals, food waste, 285–287 value-added products, 279 Van Krevelen diagram, 337f Vehicles, for food waste collection, 80–83, 83–84f Vermicompost, 236, 245–246 Volatile fatty acids (VFAs), 141–142, 164–165, 174, 290–291, 364, 367 analytical determination of, 225 bioenergy and high-value chemicals, 217–218 biological nutrient removal, 217 bioplastics, 216 hydraulic retention time (HRT), 210–211 individual VFAs, application and market value of, 215–216, 215f market value, 7 organic loading rate (OLR), 211–212 oxygen, 212 pH value, 7, 173, 173f, 207–209, 208f physical and chemical characteristics of, 206, 206t production, by anaerobic digestion process, 7, 164–165, 188–190, 190t, 207–215 recovery and purification of, 218–225 substrate, 212–215, 214t

Index temperature, 209–210 VFA mixture, application of, 216–218 Volatile solids (VS), 17–22, 18–21t, 54–58, 164–165, 172

W Waste and Resources Action Programme (WRAP), 381–385, 411–412 carbohydrate contents, of food waste, 32–34 food waste definition, 45–46 “Love Food Hate Waste,” campaign on, 4–5, 117–119 Waste-to-energy (WTE) technology, 357–358

429

Wastewater treatment plants (WWTPs), 363, 366 Welsh Assembly Government (WAG), 386 Wheat straw combustion, bioadhesives synthesis, 293 WWF Greece, 119, 119f

X Xylanases, 263–265

Y Your Business is Food (YBIF), 384

Z Zero waste discharge, 191–192, 191f