Membrane-distillation in desalination 9781315117553, 131511755X, 9781498748551, 1498748554, 9781498748544

Table of contents :
Content: 1. The Water Nexus and Desalination2. Membrane Distillation Desalination Principles andConfigurations3. Membranes for Membrane Distillation in Desalination4. Membrane Distillation Module Design5. Membrane Distillation Performance Analysis6. Membrane Fouling and Scaling in Membrane Distillation7. Membrane Improvement in Membrane Distillation8. Modeling of Membrane Distillation9. Low-Carbon Energy Sources for Membrane DistillationProcesses for Desalination10. Conclusions and Future Horizons for Membrane DistillationDesalination

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MEMBRANE-DISTILLATION IN DESALINATION Farid Benyahia

Membrane-Distillation in Desalination

Membrane-Distillation in Desalination

Farid Benyahia

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2019 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-1-4987-4854-4 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging‑in‑Publication Data Names: Benyahia, Farid, author. Title: Membrane-distillation in desalination / Farid Benyahia. Description: New York, NY: CRC Press/Taylor & Francis Group, 2019. | Includes bibliographical references and index. Identifiers: LCCN 2019015119 | ISBN 9781498748544 (hardback: acid-free paper) | ISBN 9781315117553 (ebook) Subjects: LCSH: Saline water conversion. Classification: LCC TD480.4 .B46 2019 | DDC 628.1/674--dc23 LC record available at https://lccn.loc.gov/2019015119 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

This book is dedicated to the millions of people on this planet denied their human right to water and sanitation (UN General assembly resolution 64/292, July 2010).

Contents Preface ......................................................................................................................xi Author ................................................................................................................... xiii 1. The Water Nexus and Desalination ............................................................ 1 1.1 Introduction: The Twenty-First Century Context for the Pursuit of Sustainable Water Resources ............................................ 1 1.2 Increasing Water Supply ......................................................................6 1.3 Exploiting the Vast Salty Water Resources: Desalination ...............7 1.3.1 Lessons from Desalination Literature and Industrial Practice ....................................................................9 1.4 Improved Environmental Impacts on the Ecosystem ................... 11 1.5 Prospects of Solar Energy in Desalination ...................................... 11 1.6 Concluding Remarks .......................................................................... 12 References ....................................................................................................... 13 2. Membrane Distillation Desalination Principles and Configurations.............................................................................................. 19 2.1 Membrane Distillation: Fast Growing Research Topic for Desalination ................................................................................... 19 2.2 Membrane Distillation Principles ..................................................... 21 2.3 Direct Contact Membrane Distillation (DCMD) ............................22 2.4 Vacuum Membrane Distillation (VMD) .......................................... 25 2.5 Air Gap Membrane Distillation (AGMD) ........................................ 26 2.6 Sweeping Gas Membrane Distillation (SGMD) .............................. 26 2.7 Concluding Remarks .......................................................................... 27 References ....................................................................................................... 27 3. Membranes for Membrane Distillation in Desalination ..................... 33 3.1 Introduction ......................................................................................... 33 3.2 Membrane Hydrophobicity ............................................................... 35 3.2.1 Definition of Hydrophobicity in Membranes for Membrane Distillation .................................................... 35 3.3 Materials for Hydrophobic Membranes .......................................... 36 3.4 Membrane Shape................................................................................. 37 3.5 Hydrophobic Membrane Characterization ..................................... 39 3.5.1 Contact Angle ......................................................................... 40 3.5.2 Liquid Entry Pressure ........................................................... 41 3.5.3 Membrane Pore Size and Porosity.......................................42

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3.5.4 Membrane Thickness ............................................................42 3.5.5 Pore Tortuosity .......................................................................42 3.5.6 Thermal Conductivity ...........................................................42 3.5.7 Concluding Remarks .............................................................43 References .......................................................................................................43 4. Membrane Distillation Module Design .................................................. 49 4.1 Introduction ......................................................................................... 49 4.2 Module Geometric Considerations ..................................................54 4.2.1 Rectangular Modules ............................................................ 59 4.2.2 Cylindrical Modules .............................................................. 60 4.3 Novel Module Configurations ..........................................................64 4.4 Fluid Dynamics and Heat Transfer Considerations: Qualitative Considerations ................................................................64 4.5 Practical Considerations..................................................................... 66 4.6 Concluding Remarks .......................................................................... 67 References ....................................................................................................... 67 5. Membrane Distillation Performance Analysis ...................................... 73 5.1 Introduction ......................................................................................... 73 5.2 Distillate Flux Performance ............................................................... 78 5.2.1 Flat Sheet Membranes ........................................................... 78 5.2.1.1 Effect of Membrane Properties: Material, Thickness, Pore Size, Pore Size Distribution ...... 78 5.2.1.2 Effect of Temperature ............................................ 79 5.2.1.3 Effect of Flowrates and Feed Recirculation ........80 5.2.1.4 Effect of Turbulence Promoters (Spacers) ........... 82 5.2.1.5 Effect of Flow Direction (Counter-Current vs Co-current) .........................................................83 5.2.1.6 Effect of Feed Concentration ................................83 5.2.2 Hollow Fiber (Capillary Membranes) .................................84 5.2.3 Multistage MD Systems and Novel Module Design ........ 85 5.3 Energy Efficiency ................................................................................85 5.4 Distillate Quality ................................................................................. 89 5.5 Field Testing ......................................................................................... 89 5.6 Membrane Distillation System Optimization................................. 91 5.7 Concluding Remarks .......................................................................... 91 References ....................................................................................................... 91 6. Membrane Fouling and Scaling in Membrane Distillation .............. 101 6.1 Introduction ....................................................................................... 101 6.2 Flux and Flux Decline in Membrane Distillation ........................ 107 6.3 Fouling and Scaling in Membrane Distillation ............................ 109

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6.4 Membrane Autopsy Techniques in Membrane Distillation ....... 110 6.5 Membrane Wetting and Distillate Quality Deterioration ........... 110 6.6 Fouling Mitigation Measure in Membrane Distillation .............. 111 6.7 Future Directions in Membrane Fouling Resistance Efforts ...... 111 6.8 Concluding Remarks ........................................................................ 112 References ..................................................................................................... 112 7. Membrane Improvement in Membrane Distillation .......................... 117 7.1 Introduction ....................................................................................... 117 7.2 Membrane Material and Surface Modifications ........................... 119 7.2.1 Enhancing Membrane Flux ................................................ 119 7.2.2 Enhanced Membrane Hydrophobicity and Wetting Resistance .............................................................................. 120 7.2.3 Enhanced Mechanical Properties...................................... 121 7.3 New and Novel Membrane Distillation Membranes .................. 122 7.4 Omniphobic and Amphiphobic Membranes ................................ 122 7.5 Bioinspired MD Membranes ........................................................... 125 7.6 Novel Janus Membranes .................................................................. 125 7.7 Concluding Remarks ........................................................................ 125 References ..................................................................................................... 126 8. Modeling of Membrane Distillation ...................................................... 133 8.1 Introduction ....................................................................................... 133 8.2 Types of Models for Membrane Distillation ................................. 136 8.3 Model Formulation ........................................................................... 140 8.4 Models for Various Membrane Distillation Configurations ....... 146 8.5 Models Output .................................................................................. 146 8.6 Main Challenges in Membrane Distillation Modeling ............... 146 8.7 Emergence of Computational Fluid Dynamics in Membrane Distillation Modeling ....................................................................... 147 8.8 Concluding Remarks ........................................................................ 147 References ..................................................................................................... 148 9. Low-Carbon Energy Sources for Membrane Distillation Processes for Desalination ....................................................................... 157 9.1 Introduction ....................................................................................... 157 9.1.1 Low-Grade Waste Heat ....................................................... 158 9.1.2 Solar Energy Harvesting for Desalination ....................... 158 9.1.3 Low-Grade Waste and Solar Energy Recovery for Membrane Distillation Desalination .......................... 159 9.2 Low-Grade Heat Sources and Utilization in Membrane Distillation.......................................................................................... 161 9.3 Solar Energy Sources for Membrane Distillation......................... 164

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9.4

Main Challenges in Tapping Low-Grade Heat in Membrane Distillation ......................................................................................... 167 9.5 Main Challenges in Tapping Solar Energy in Membrane Distillation ......................................................................................... 167 9.6 Concluding Remarks ........................................................................ 168 References ..................................................................................................... 169 10. Conclusions and Future Horizons for Membrane Distillation Desalination ................................................................................................ 173 10.1 Introduction ....................................................................................... 173 10.2 Outstanding Issues That Hinder Commercial Deployment of Membrane Distillation for Desalination ................................... 173 10.3 Cost Competitivity Issues ................................................................ 174 10.4 Sustainability Issues of Membranes for Membrane Distillation ........................................................................................ 175 10.5 Target Applications of Membrane Distillation for Desalination ................................................................................ 175 10.6 Emergence of Computational Fluid Dynamics in Membrane Distillation Modeling .............................................. 176 References ..................................................................................................... 176 Index ..................................................................................................................... 179

Preface Membrane distillation for desalination is a very popular topic for research with graduate students and research staff in general, worldwide. It is an emerging technology for water treatment, especially for desalting seawater and high salinity industrial waste streams using low carbon energy sources such as low-grade waste heat or solar power. It is a technology that can be deployed to remote places where communities suffer from water shortages and access to clean freshwater from the main water supply is not possible or prohibitively expensive. However, ever since its development in the nineties, its potential to produce ultra-high quality for industry where it can easily be thermally integrated to exploit low-grade waste heat has been recognized. Yet, some 30 years on we have yet to see this marvelous technology deployed on a commercial scale. The reasons are diverse: some are purely technical and related to the stability of the hydrophobic membranes used and others are related to the economics of a technology that was not given the chance it rightly deserves to be launched on a large scale. However, the massive growth in interest in membrane technology is encouraging, and many are hopeful that it will be deployed in the not too distant future owing to the impressive amount of work done on the topic. This book is a concise reference book rich in content and literature references suitable for a wide range of readers: new graduate students, new research assistants, university professors and laboratory technicians. For such a diverse audience, the style of the write-up and depth/breadth of content was very carefully selected. It does not go too deep in every topic but provides the most salient issues in good detail, providing ample references for those who wish to dig deeper into the various topics. The book also contains an important introduction chapter on the current water situation worldwide where water-stressed regions are no longer the low GDP nations but almost every nation on Earth regardless of their degree of affluence. This book, in its first edition, will be the friendly companion of young researchers who wish to invest their future career on low carbon water technologies.

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Author

Farid Benyahia is a professor of chemical engineering and fellow of the institution of chemical engineers, currently affiliated with the school of chemical engineering at the University of Birmingham in the United Kingdom. He held previously positions of faculty member and head of department in the Gulf and was prior to that senior lecturer in the United Kingdom. He was educated at the Universities of Newcastle and Aston in the United Kingdom. His research interests include low carbon desalination, carbon management, concentrated brine management, contaminated soils and water treatment, and multiphase reactor systems.

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1 The Water Nexus and Desalination

1.1 Introduction: The Twenty-First Century Context for the Pursuit of Sustainable Water Resources Humanity embarked on the twenty-first century facing a number of challenges leaving politicians, visionaries and academics pondering on elusive solutions for a long time to come. Some such major challenges include water resources, energy, food security and population. This is by no means an exhaustive list. However, the four challenges mentioned are intimately related. By far, availability and access to clean freshwater constitute the major concern to decision makers globally. Indeed, the inexorable increase in the world population over the past decades put a considerable strain on Earth’s freshwater. While planet Earth has an immense salt water inventory in the form of oceans and seas, freshwater constitutes a mere 2.5% of the global total water and from this fraction, nearly 69% of freshwater is locked as frozen glaciers and permanent icecaps, leaving just over 30% of freshwater available as groundwater and 0.3% of freshwater available as surface water. Surface freshwater constitutes a tiny 0.3% of freshwater available and the remaining 0.9% are accounted for as soil moisture, permafrost and swamps. This remarkable and striking estimate reported by Igor Shiklomanov [1] still remains a valuable reference for the global freshwater inventory of planet Earth. Figure 1.1 depicts Earth’s global water and freshwater distribution. Unlike other natural resources, water circulates naturally according to the global hydrological cycle offering the possibility to recharge natural and man-made water catchments. However, according to Oki and Kanae [2], it is the flow of water that should be the focus rather than the stock in the assessment of water resources. Oki and Kanae [2] also pointed out that due to the long time it may take to recharge groundwater reservoirs naturally to their original volume stored, if ever, groundwater has sometimes been called “fossil water.”

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Membrane-Distillation in Desalination

FIGURE 1.1 Earth’s global water and freshwater distribution.

This is particularly significant when groundwater is being withdrawn in many parts of the world at a rate that exceeds natural recharging [3–5] and that globally, about 70%–80% of the total water consumed is used in agriculture [1,6]. The surge in freshwater consumption is primarily due to an increasing world population that needs food from agricultural activity, industrial activities and urban/rural development to maintain or improve its lifestyle. The most recent United Nations population census [7] depicts an unprecedented upward trend in the past decades, reaching 7.63 billion in 2017 and projected to reach over 10  billion past the 2050 horizon. Figure  1.2  shows the world

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The Water Nexus and Desalination

FIGURE 1.2 The world population trend from the 1950s to the 2100 horizon.

population trend from the 1950s to the 2100 horizon. It can be seen that the major fraction of the world population is currently (2017) located in Asia (59.87%), followed by Africa (16.18%), Europe (10.03%), Latin America (8.57%), North America (4.82%) and finally Oceania (0.54%). The population growth in Figure 1.2 indicates that the global population will continue an upward trend with the exception of Europe where a negative growth may be experienced past the 2025 horizon. Because the uneven distribution of renewable freshwater reserves (RFWR) has been somewhat exacerbated by the climate system, most regions in the world, regardless of the status of economic development or wealth, have been affected by water shortages intermittently or permanently. Consequently, a measure of water scarcity has been put forward in the form indices commonly called water scarcity indices. These indices have been reviewed by Brown and Matlock [8]. However, the simplest water scarcity index covered by Oki and Kanae [2] has been used to map water-stressed regions in the world. This water scarcity index is represented by the following equation: Rws =

W −S Q

(1.1)

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Membrane-Distillation in Desalination

TABLE 1.1 Water Scarcity Scale Rws