advanced membrane technology

Baker, Membrane Technology and Research, Inc., Menlo Park, California94025Dibakar Bhattacharyya, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kent

TECHNOLOGY AND

APPLICATIONS

ADVANCED MEMBRANE TECHNOLOGY AND

APPLICATIONS

Edited By

Norman N Li, Anthony G Fane,

W S Winston Ho, and T Matsuura

Published by John Wiley & Sons, Inc., Hoboken, New Jersey

Published simultaneously in Canada

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008,

or online at http://www.wiley.com/go/permission.

Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose No warranty may be created or extended by sales representatives or written sales materials The advice and strategies contained herein may not be suitable for your situation You should consult with a professional where appropriate Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at

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Wiley also publishes its books in a variety of electronic formats Some content that appears in print may not be available in electronic format For more information about Wiley products, visit our web site at www.wiley.com Library of Congress Cataloging-in-Publication Data:

Advanced membrane technology and applications/edited by Norman N Li [et al.].

1.6 Low-Fouling RO Membrane for Wastewater Reclamation 141.7 Chlorine Tolerance of Cross-Linked Aromatic Polyamide Membrane 17

2 Cellulose Triacetate Membranes for Reverse Osmosis 21

A Kumano and N Fujiwara

2.4 Actual Performance of Toyobo RO Module for Seawater Desalination 282.5 Most Recent RO Module of Cellulose Triacetate 35

v

4.2 SWRO Energy Reduction Using Energy Recovery Technology 88

N Kubota, T Hashimoto, and Y Mori

5.2 Recent Trends and Progress in MF/UF Technology 104

6 Water Treatment by Microfiltration and Ultrafiltration 131

M D Kennedy, J Kamanyi, S G Salinas Rodrı´guez, N H Lee,

J C Schippers, and G Amy

6.2 Materials, Module Configurations, and Manufacturers 1336.3 Microfiltration/Ultrafiltration Pretreatment 142

6.6 Integrated Membrane Systems (MF or UFþ RO or NF) 1606.7 Backwash Water Reuse, Treatment, and Disposal 164

7.8 Water Reuse versus Desalination 185

P Cornel and S Krause

9.2 Principle of the Membrane Bioreactor Process 217

Anthony G Fane

11.3 Application of Nanofiltration for Production of Drinking Water

CONTENTS vii

12.2 Membrane Distillation Membranes and Modules 30512.3 Membrane Distillation Membrane Characterization Techniques 32012.4 Transport Mechanisms in MD: Temperature Polarization,

Concentration Polarization, and Theoretical Models 331

12.6 Long-Term MD Performance and Membrane Fouling in MD 355

15.3 Basic Working Principles of Ultrafiltration 437

P Silva, L G Peeva, and A G Livingston

16.2 OSN Transport Mechanisms—Theoretical Background 45816.3 Applications of Organic Solvent Nanofiltration 461

Fakhir U Baig

17.4 Permeation and Separation Model in Hollow-Fiber

G Catapano and J Vienken

18.5 Biocompatibility of Membrane-Based Therapeutic Treatments 508

19.4 Membrane Materials, Spinning Technology, and Structure 527

Richard W Baker

22.2 Permeability and Chemical Structure of Polyimides 582

22.5 Applications of Polyimide Gas Separation Membranes 589

P Jason Williams and William J Koros

23.6 Production of CMS Modules 62023.7 Challenges and Disadvantages of CMS Membranes 622

24.5 Membrane Gas Separation Applications and Conclusions 659

26.2 Membrane-Based Contacting of Two Fluid Phases 690

26.5 Dispersive Contacting in a Membrane Contactor 699

Enrico Drioli and Enrica Fontananova

27.1 State-of-the-Art On Catalytic Membrane Reactors 70327.2 Advanced Oxidation Processes for Wastewater Treatments 704

27.4 Biocatalytic Membrane Reactors 712

28 Facilitated Transport Membranes for Environmental, Energy,

Jian Zou, Jin Huang, and W S Winston Ho

Peter N Pintauro and Ryszard Wycisk

Chunqing Liu, Santi Kulprathipanja, Alexis M W Hillock,

Shabbir Husain, and William J Koros

31.3 Recent Progresses on Single-Layer Asymmetric Hollow-Fiber

M Kallioinen and M Nystro¨m

32.2 Characterization of the Chemical Structure of a Membrane 84232.3 Characterization of Membrane Hydrophilicity 852

33.3 Characterization of Inorganic Membrane Fouling 882

34 Microstructural Optimization of Thin Supported Inorganic

M L Mottern, J Y Shi, K Shqau, D Yu, and Henk Verweij

34.3 Optimization of Supported Membrane Structures 908

35 Structure/Property Characteristics of Polar Rubbery Membranes

Victor A Kusuma, Benny D Freeman, Miguel Jose-Yacaman, Haiqing Lin,

Sumod Kalakkunnath, and Douglass S Kalika

& PREFACE

Since the last membrane book I published with the New York Academy of Sciences, I haveattended several quite large membrane conferences including the one that I organized inthe beautiful city of Irsee, Germany I was struck by the fact that there had been verygood progress made in the broad field of membranes science and technology Also, mem-branes seem to be coming to the center of the water treatment and desalination technologies.Many parts of the world now are in critical need of clear water Membrane technology isgaining increasing importance in treating and reusing wastewater and in producingpotable water from seawater It appears there is a timely need for a book that comprehen-sively reviews the up-to-date membrane technology and its many applications

To undertake the task of publishing this book, I invited three of my colleagues, TonyFan, Winston Ho, and Takeshi Matsuura to help, thus a team of four editors Together

we invited 35 chapters to cover membrane applications from gas to water separations.These chapters are now divided into six categories—membranes and applications inwater and wastewater, membranes and applications in biotechnology and biomedicalengineering, gas separations, membrane contactors and reactors, environmental andenergy applications, and membrane materials and characterization These six categoriesindeed cover a very broad field of applications

I believe three somewhat unique features can be said about these chapters One is that thepercentage of contributors from industry is high This is, of course, a relative comparison, ingeneral, with the other published membrane books As we know, most of the authors of thechapters in a membrane book are from academia, whereas many of the contributors fromthis book are from some of the major international membrane manufacturing companies.The other feature is that the chapters, in general, are more into applications than theories.The third feature is that a very strong coverage of water treatment and purification ispresented for the reason mentioned above

We are truly gratified to the strong response to contributing chapters As a matter of fact,

we still have quite many chapters that have been promised but have not been finished Thisprompted me to consider publishing a second book in the near future Meanwhile, we areindeed very pleased to have this book published and wish to thank all the reviewers andchapter contributors

NORMANN LI

NL Chemical Technology, Inc

Mount Prospect, Illinois

xv

Dr Norman N Lihas about 40 years of working experience in the chemical and petroleumindustries He was a senior scientist with Exxon Research and Engineering Co, Director ofSeparation Science and Technology at UOP Co and Director of Research and Technology

at AlliedSignal Co (now part of Honeywell) Since 1995, he is the president of NLChemical Technology, Inc., which focuses on the development of membrane technologies

Dr Li has more than 100 technical publications, 44 U.S patents, and 13 books edited, all

in the field of separation science and technology He received the prestigious Award ofSeparation Science and Technology from the American Chemical Society, the FoundersAward, Alpha Chi Sigma Award for Chemical Engineering Research, and the Award inChemical Engineering Practice from the American Institute of Chemical Engineers andthe Perkin Medal from the Society of Chemical Industry The American Institute ofChemical Engineers held special symposia on membranes in his honor at its national meet-ings in 1995 and 2000 Dr Li served as the president of the North American MembraneSociety and the chair of the International Congress on Membranes and MembraneProcesses (ICOM) in 1990 He is a member of the National Academy of Engineering,United States

Dr Tony Faneis a chemical engineer with a Ph.D from Imperial College, London He hasbeen working on membranes since 1973 when he joined the University of New SouthWales, in Sydney, Australia His current interests are in membranes applied to environ-mental applications and the water cycle, with a focus on the sustainability aspects of mem-brane technology He is a former director of the UNESCO Centre for Membrane Scienceand Technology at UNSW and recently Temasek Professor at Nanyang TechnologicalUniversity, Singapore He is currently director of the Singapore Membrane TechnologyCentre at NTU He is on the editorial board of the Journal of Membrane Science andDesalination He is a fellow of the Australian Academy of Technological Sciences andEngineering, a recipient of the Centenary Medal in 2002 for services to ChemicalEngineering and the Environment, and an honorary life member of the EuropeanMembrane Society

Dr W S Winston Hois University Scholar Professor of Chemical and Materials Scienceand Engineering at the Ohio State University since 2002 Previously, he was a professor ofchemical engineering at the University of Kentucky, after having more than 28 years ofindustrial R&D experience with Allied Chemical, Xerox, and Exxon, and serving assenior vice-president of technology at Commodore Separation Technologies He waselected a member of the National Academy of Engineering, United States, in 2002 ANew Jersey Inventor of the Year (1991), Dr Ho holds more than 50 U.S patents inseparation processes He is co-editor of Membrane Handbook and the recipient of theProfessional and Scholarly Publishing Award for the most outstannding engineeringwork in 1993 He received the 2006 Institute Award for Excellence in Industrial Gases

xvii

Technology and the 2007 Clarence G Gerhold Award from AIChE He obtained his B.S.degree from National Taiwan University and his M.S and Ph.D degrees from theUniversity of Illinois at Urbana – Champaign, all in chemical engineering.

Dr Takeshi Matsuura received his B.Sc and M.Sc degrees from the Department ofApplied Chemistry, University of Tokyo, and his doctoral degree from the Institute ofChemical Technology of the Technical University of Berlin in 1965 After working atthe Department of Synthetic Chemisty of the University of Tokyo as a staff assistant and

at the Department of Chemical Engineering of the University of California as a postdoc,

he joined the National Research Council of Canada in 1969 He became a chair professor

at the University of Ottawa in 1992 He also served as the director of the IndustrialMembrane Research Institute until he retired in 2002 He is now a visiting professor

at the National University of Singapore and the University Technology Malaysia,Skudai Dr Matsuura received the Research Award of International Desalination andEnvironmental Association in 1983 A symposium of membrane gas separation was held

at the Eighth Annual Meeting of the North American Membrane Society, May 18 – 22,

1996, Ottawa, to honor him and Dr S Sourirajan He received the George S LinksAward for Excellence in Research from University of Ottawa in 1998 He has publishedmore than 300 articles in refereed journals, authored and co-authored 3 books, andedited 4 books

Fakhir U Baig, Petro Sep Membrane Technologies Inc., Oakville, Ontario, CanadaRichard W Baker, Membrane Technology and Research, Inc., Menlo Park, California94025

Dibakar Bhattacharyya, Department of Chemical and Materials Engineering, University

of Kentucky, Lexington, Kentucky 40506-0046

Bart Van Der Bruggen and Jeroen Geens, Department of Chemical Engineering,Laboratory for Applied Physical Chemistry and Environmental Technology, University

of Leuven, Leuven, Belgium

G Catapano, Department of Chemical Engineering and Materials, University of Calabria,Rende (CS), Italy

Tai-Shung Neal Chung, Department of Chemical and Biomolecular Engineering,National University of Singapore, Singapore 119260

P Cornel, Technische Universita¨t Darmstadt, Department of Civil Engineering, InstituteWAR, Darmstadt, Germany

Pierre Coˆte´ and Mingang Liu, GE Water and Process Technologies, ZENON MembraneSolutions, Ontario, L6M 4B2, Canada

Zhanfeng Cui, Department of Engineering Science, Oxford University, Oxford, UnitedKingdom

Avijit Dey, Director – Application and Research, Omexell Inc., Stafford, Texas 77477Enrico Drioli and Enrica Fontananova, Institute on Membrane Technology of theNational Council Research (ITM-CNR), and Department of Chemical Engineering andMaterials, University of Calabria, Rende (CS), Italy

Anthony G Fane, UNESCO Centre for Membrane Science & Technology, University ofNew South Wales, Australia 2052 and Singapore Membrane Technology Centre,Nanyang Technological University, Singapore

Raja Ghosh, Department of Chemical Engineering, McMaster University, Hamilton,Ontario L8S 4L7, Canada

Alan R Greenberg, Department of Mechanical Engineering, University of Colorado,Boulder, Colorado 80309-0427

Alexis M W Hillock, Shabbir Husain, and William J Koros, School of Chemical &Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332

xix

Sumod Kalakkunnath, Department of Chemical and Materials Engineering and Centerfor Manufacturing, University of Kentucky, Lexington, Kentucky 40506-0046

Douglass S Kalika, Department of Chemical and Materials Engineering and Center forManufacturing, University of Kentucky, Lexington, Kentucky 40506-0046

M Kallioinen and M Nystro¨m, Laboratory of Membrane Technology and TechnicalPolymer Chemistry, Department of Chemical Technology, Lappeenranta University ofTechnology (LUT), Lappeenranta, Finland

Sujatha Karoor, Renal Division, Baxter Healthcare Corp., McGaw Park, Illinois,Massachusetts

Yoji Kase, UBE Industries Ltd., Ichihara, Chiba 290-0045, Japan

M D Kennedy, J Kamanyi, S G Salinas Rodrı´guez, N H Lee, J C Schippers, and

G Amy, UNESCO – IHE Institute for Water Education, 2601 DA Delft, TheNetherlands

Mohamed Khayet, Department of Applied Physics I, Faculty of Physics, UniversityComplutense of Madrid, Madrid, Spain

William B Krantz, Department of Chemical and Biomolecular Engineering, NationalUniversity of Singapore, The Republic of Singapore, 117576

S Krause, Microdyn-Nadir GmbH, Wiesbaden, Germany

N Kubota, T Hashimoto, and Y Mori, Microza Research & Development Department,Specialty Products & Systems R&D Center, Asahi Kasei Chemicals Corporation, FujiCity, Shizuoka, 416-8501 Japan

A Kumano and N Fujiwara, Desalination Membrane Operating Department, ToyoboCo., Ltd., Osaka, Japan

Victor A Kusuma, Benny D Freeman, and Miguel Jose-YacamaN, Department ofChemical Engineering, University of Texas at Austin, Austin, Texas 78712

Haiqing Lin, Membrane Technology and Research, Inc., Menlo Park, California 94025Chunqing Liu and Santi Kulprathipanja, UOP LLC, 25 East Algonquin Road, DesPlaines, Illinois, 60017

Yi Hua Ma, Center for Inorganic Membrane Studies, Department of ChemicalEngineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609

M L Mottern, J Y Shi, K Shgau, D Yu, and Henk Verweiji, Department of MaterialsScience & Engineering, The Ohio State University, Columbus, Ohio 43210-1178Norma J Ofsthun, Clinical Science Department, Fresenius Medical Care, Lexington,Massachusetts 02420

Ho Bum Park and Young Moo Lee, School of Chemical Engineering, HanyangUniversity, Seoul, South Korea

Peter N Pintauro and Ryszard Wycisk, Department of Chemical Engineering, CaseWestern Reserve University, Cleveland, Ohio 44106-7217

xx CONTRIBUTORS

Raphael Semiat, Technion, Israel Institute of Technology, The Wolfson ChemicalEngineering Department, Technion City, Haifa, Israel

P Silva, L G Peeva, and A G Livingston, Department of Chemical Engineering,Imperial College, London SW7 2BY, United Kingdom

Kamalesh K Sirkar, Otto H York Department of Chemical Engineering, Center forMembrane Technologies, New Jersey Institute of Technology, Newark, New Jersey07102

Steven Siverns, EnviroTower, Toronto, Ontario, M5V 1R7, Canada

Mitsuru Suzuki, Medical Membrane Department, Toyobo Corp., Osaka, Japan

Yit-Hong Tee, Department of Chemical and Materials Engineering, University ofKentucky, Lexington, Kentucky 40506-0046

R L Truby, Toray Membranes, Escondido, California 92026

Tadahiro Uemura and Masahiro Henmi, Global Environment Research Laboratories,Toray Industries Inc., Otsu Shiga, Japan

J Vienken, Fresenius Medical Care, Bad Homburg, Germany

Nikolay Voutchkov, Poseidon Resources Corporation, Stamford, Connecticut

S Ranil Wickramasinghe, Department of Chemical and Biological Engineering,Colorado State University, Fort Collins, Colorado 80523-1370

P Jason Williams and William J Koros, School of Chemical and BiomolecularEngineering, Georgia Institute of Technology, Atlanta, Georgia 30332

Jian Zou, Jin Huang, and W S Winston Ho, Department of Chemical andBiomolecular Engineering, Department of Materials Science and Engineering, TheOhio State University, Columbus, Ohio 43210-1180

&PART I

MEMBRANES AND APPLICATIONS IN WATER AND WASTEWATER

Thin-Film Composite Membranes for

Reverse Osmosis

TADAHIRO UEMURA and MASAHIRO HENMI

Global Environment Research Laboratories, Toray Industries Inc., Otsu Shiga, Japan

1.1 INTRODUCTION

Because of vastly expanding populations, increasing water demand, and the deterioration ofwater resource quality and quantity, water is going to be the most precious resource in theworld Thus, the 21st century is called the “water century.” In the 20th century, membranetechnologies made great progress, and commercial markets have been spreading veryrapidly and throughout the world The key technologies fueling this progress are as follows:

1 Materials: Chemical design of high-performance materials suitable for each ation mode

separ-2 Morphology: Morphological design of high-performance membranes

3 Element/Module: Element and module design for high-performance membranes

4 Membrane Process: Plant design and operation technology

In 21st century, to solve these water problems, membranes technology is going to be furtherexpanded and new technology—further improvements of membrane performance, develop-ment of membrane systems, membranes stability such as antifouling membranes forwastewater treatment, and other highly qualified membranes—will be needed

Among desalination technologies available today, reverse osmosis (RO) is regarded asthe most economical desalination process Therefore, RO membranes have played crucialroles in obtaining fresh water from nonconventional water resources such as seawaterand wastewater

1.2 APPLICATION OF RO MEMBRANES

Reverse osmosis membranes have been used widely for water treatment such as ultrapurewater makeup, pure boiler water makeup in industrial fields, seawater and brackish water

Advanced Membrane Technology and Applications Edited by Norman N Li, Anthony G Fane,

W S Winston Ho, and T Matsuura

Copyright # 2008 John Wiley & Sons, Inc.

3

desalination in drinking water production, and wastewater treatment and reuse in industrial,agricultural, and indirect drinking water production as shown in Table 1.1.

The expansion of RO membrane applications promoted the redesign of suitablemembrane material to take into consideration chemical structure, membranes configuration,chemical stability, and ease of fabrication And along with the improvements of themembranes, the applications are further developed

1.3 MAJOR PROGRESS IN RO MEMBRANES

1.3.1 Cellulose Acetate Membrane

Reverse osmosis systems were originally presented by Reid in 1953 The first membrane,which could be used at the industrial level in actual water production plants, was acellulose-acetate-based RO membrane invented by Loeb and Sourirajan in 1960 Thismembrane has a so-called asymmetric or anisotropic membrane structure having a verythin solute-rejecting active layer on a coarse supporting layer, as shown in Figure 1.1.The membrane is made from only one polymeric material, such as cellulose acetate, andmade by the nonsolvent-induced phase separation method After the invention by Loeband Sourirajan, spiral-wound membranes elements using the cellulose acetate asymmetricflat-sheet membranes were developed and manufactured by several U.S and Japanesecompanies RO technologies have been on the market since around 1964 (Kurihara et al.,1987) They were widely used from the 1960s through the 1980s mainly for pure watermakeup for industrial processes and ultrapure water production in semiconductor industries;and some are still used in some of these applications

Ultrapure water, boiler

water, process pure

water, daily

industries

Seawater desalination, brackish water desalination

Industrial water, agricultural water, indirect drinking water

4 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

1.3.2 Aromatic Polyamide Hollow Fiber Membrane

Since then, there has been intensive and continuous R&D efforts mainly around the UnitedStates and Japan to meet the demands from commercial markets, and there exist manyinventions and breakthroughs in membrane materials and configurations to improve theperformances of membranes

To overcome the problems of cellulose acetate membranes, many synthetic polymericmaterials for reverse osmosis were proposed, but except for one material, none of themproved successful The only one material, which could remain on the market, was thelinear aromatic polyamide with pendant sulfonic acid groups, as shown in Figure 1.2.This material was proposed by DuPont, which fabricated very fine hollow fiber membranes;the modules of this membrane were designated B-9 and B-10 They have a high rejectionperformance, which can be used for single-stage seawater desalination They were widelyused for mainly seawater or brackish water desalination and recovery of valuable materialssuch as electric deposition paints, until DuPont withdrew them from the market in 2001.1.3.3 Composite Membrane

Another approach to obtain a high-performance RO membrane was investigated by someresearch institutes and companies in the 1970s Many methods to prepare compositemembranes have been proposed, as shown in Table 1.2 In the early stage, very thinfilms of a cellulose acetate (CA) polymer coating on a substrate, such as a porous cellulosenitrate substrate, was tried However, in spite of their efforts, this approach did not succeed

in industrial membranes manufacturing

The next approach used the interfacial polycondensation reaction to form a very thinpolymeric layer onto a substrate Morgan first proposed this approach (Morgan, 1965),and then Scala et al (1973) and Van Heuven (1976) actually applied this approach toobtain an RO membrane But it was Cadotte who invented the high-performance membraneusing the in situ interfacial condensation method (Cadotte, 1985) In his method, interfacialcondensation reactions between polymeric polyamine and monomeric polyfunctional acidhalides or isocyanates takes place on a substrate material to deposit a thin film barrier onto asubstrate Some of the composite membranes were succeeded in industrial fabrication byanother method, which was designated as PA-300 or RC-100

Another preparation method for composite membrane is an in situ monomer densation method using the monomeric amine and monomeric acid halide, which wasalso invented by Cadotte Then, many companies succeeded in developing compositemembranes using this method, and the membrane performance has been drasticallyimproved up to now Now, composite membrane of cross-linked fully aromatic polyamide

con-is regarded as the most popular and reliable material in the world Permeate flow rate and itsquality have been improved 10 times greater than that of the beginning (Kurihara et al.,

1987, 1994b)

1.4 TRENDS IN RO MEMBRANE TECHNOLOGY

Figure 1.3 shows recent trends in RO membrane technology with two obvious tendencies.One is a tendency toward low-pressure membranes for operating energy reduction in thefield of brackish water desalination The other is a tendency toward high rejection withhigh-pressure resistance in the large seawater desalination market

6 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

1.4.1 Progress of Low-Pressure Membrane Performance

in Brackish Water Desalination

Figure 1.4 shows the progress of low-pressure membrane performance trends in ROmembrane on brackish water desalination from the 1970s to the 1990s, including industrialwater treatment such as ultrapure water production In the 1970s much effort was devoted to

developing high-performance membrane materials and improving the membrane ance As a result performance was improved with a new developed material of cross-linkedaromatic polyamide and by developing membrane morphology and fabrication technology.The cross-linked fully aromatic polyamide composite membrane developed in 1987 hasfour or five times larger water flux and five times higher product water quality thanthose of the CA membrane (Kurihara et al., 1987) Since 1987, membrane performancehas been drastically developed On the basis of the development of cross-linked fully aro-matic polyamide composite membranes, RO membrane performance of brackish waterdesalination has improved very rapidly Typical performances of the RO elements forbrackish water desalination are shown in Table 1.3 The ultralow-pressure membrane,which can be used at ultralow pressures such as 0.75 MPa, has been developed, whichsaves on the operating cost (Ikeda et al., 1996) And now the super-ultralow-pressure mem-brane elements, which can be used at super-ultralow-pressure, such as 0.5 – 0.3 MPa, havebeen developed (Fusaoka, 1999) This membrane has three times the water permeabilitythan the ordinary low-pressure RO membrane This membrane can operate with one-third the pressure of a low-pressure membrane.

perform-1.4.2 Progress of RO Membranes for Seawater Desalination

The progress of RO membranes for seawater desalination is shown in Figure 1.5 (Kurihara

et al., 1994a) It is very important to increase the water recovery ratio on seawater nation systems to achieve further cost reduction Most seawater RO desalination systems

desali-in use today are confdesali-ined to approximately 40% conversion of the feed water (salt tration 3.5%), since most of commercially available RO membrane do not allow forhigh-pressure operation of more than around 7.0 MPa

concen-Recent progress on high-pressure – high-rejection spiral wound (SW) RO elements, bined with proven and innovative energy recovery and pumping devices, has opened newpossibilities to reduce investment and operating cost The progress of RO seawater desali-nation from a point of view of water recovery is shown in Table 1.4 (Moch, 2000).Toray has developed a new low-cost seawater desalination system called the BrineConversion Two-Stage (BCS) system, as shown in Figure 1.6, which provides 60%

Type of Membrane

Low Pressure

Ultralow Pressure

Super-ultralow Pressure

Name of membrane element

(in market: year)

SU-720 (1987)

SU-720L (1988)

SUL-G20 (1996)

SUL-H20 (1999) Performance

8 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

water recovery of freshwater (Yamamura et al., 1996) Ohya et al (1996) and Nakao (1996)also suggest that higher recovery of RO seawater desalination by the BCS system is mosteffective in saving energy yet keeping a low operating cost.

As for achieving the 60% RO seawater desalination system, it is absolutely necessary tomake the RO membrane element, which can be operated under very severe operating con-ditions, with high pressure and high feed water concentration such as 9.0 MPa and 5.8%.Toray has developed a high-performance membrane (BCM element) that can be operated

at high pressure and high concentration conditions, as shown in Table 1.5

1.4.3 High Boron Rejection SWRO Membrane

The removal of boron is a significant problem in SWRO desalination processes (Fukunaga

et al., 1997) Boron exists as boric acid in the natural water, and boric acid mainly shows the

Ultrahigh Pressure Seawater RO Membrane SU-820BCM

Seawater RO Membrane SU-820

male reproductive tract when administered orally to laboratory animals The World HealthOrganization (WHO) proposes that boron concentration in drinking water be below 0.5 mg/

L as a provisional guideline value (WHO, 2004) However, especially in SWRO tion fields, this is not an easy goal to meet because boron concentration in seawater is com-paratively high Although conventional SWRO membrane elements have shown a littlemore than 90% of boron rejection, it is still inadequate It is difficult for RO membranes

desalina-to remove boric acid in water for the following reasons: First, the molecular size of boricacid is so small that it is difficult to remove by size exclusion Second, since boric acidhas a pKaof 9.14 – 9.25, it is not ionized in natural seawater with a pH of 7.0 – 8.0 anddissociates at pH 9 or more (Rodriguz et al., 2001) The boron rejection by the electricrepulsive force between boric acid and the membrane cannot be expected in a neutral con-dition Therefore, some posttreatment processes are necessary to meet the WHO proposal.The conventional SWRO membrane element TM820, which is typical with Toray, hasexhibited 91 – 93% boron rejection, which was the highest level achieved by commercia-lized SWRO membrane elements (Toray, 2004; Redondo et al., 2003; Hiro and Hirose,2000) This membrane element series has been installed in a large number of SWRO

plants And Toray has commercialized many types of SWRO membrane elements, whichare for different pressure ranges due to total dissolved solids (TDS) concentration and temp-erature of the seawater, as shown in Table 1.6 However, the highest boron rejection in thosemembrane elements is 91 – 93%, which is the same as TM820 This means that the improve-ment of boron rejection by membrane material had been sluggish for a while Meanwhile,the new membrane element TM820A was developed based on the following two concepts:(1) reduction of affinity with boric acid by control of hydrophobic property and functionalgroups may reject boric acid selectively, and (2) molecular structure design was considered

as blocking the boric-acid-permeable large pore (Taniguchi et al., 2004) TM820A bited 94 – 96% boron rejection with high TDS rejection and high water productivity Thespecification and typical performance of TM820A is shown in Table 1.7

exhi-Seen from various viewpoints, a single SWRO system is the most ideal Therefore, toevaluate the performance of TM820A, the amount of boron that TM820A could remove

by a single-stage operation was estimated Table 1.8 shows the permeate boron tration that corresponds to the boron rejection performance used by membrane elementswhen each region of seawater is treated by a single-stage SWRO operation consideringthe aging factor According to Table 1.8, TM820A meets the Japanese guidelines ofbelow 1 mg/L of boron concentration by a single-stage operation But in severe conditions,for the WHO guideline grade and the Middle East seawater treatment, certain posttreatmentprocesses are still needed If 97% of boron rejection performance is gained, the WHO gradewill be enabled until the Southeast Asia seawater treatment Furthermore, at 99% boron

feed solution: 32,000 ppm, NaCl with 5.0 mg/L boron; pH ¼ 8; temperature, 258C.

rejection performance, the WHO guideline grade will be enabled even in the Middle Eastseawater treatment.

Recently, Toray has been investigating SWRO membranes that focus on the removal ofboron by the improvement of membrane performance The history and future prospects ofthe boron removal at Toray and other companies are shown in Figure 1.7 Until 2000,although the boron rejection was also improved as various membranes were developed

in each company, it was 90% at best In the next period, from 2000 to 2003, the membranes

in which a little more than 90% of boron rejection was shown were released, and these serve

as main items for each company now

From 2003 to 2005, Toray developed and released TM820A, whose performance wasappreciably improved, and offered the membrane that showed around 95% boron rejectionprior to other companies However, the supportive systems are still required to meet theWHO proposal even by using TM820A as above Thus, the next target is 97 or 99%boron rejection performance of renovative membrane The further development of a new

Seawater

(Temp., TDS conc., Boron conc.)

Permeate Boron Concentration (mg/L) Boron Rejection Performance of Used Membrane Element

ratio 40%, after 3 years Japanese law grade: ,1.0 mg/L, WHO guideline grade: ,0.5 mg/L.

Toray and comparable companies.

12 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

renovative membrane that can meet the WHO proposal for every seawater continues(Tomioka et al., 2005) Table 1.9 summarizes large seawater RO desalination plantsaround the world TM820A is installed in a large seawater RO desalination plant in Singapore.

1.5 REVERSE OSMOSIS/BIOFOULING PROTECTION

Biofouling has been regarded as the most serious problem in the operation of SWRO plants.The usual method to prevent biofouling is continuous chlorine dosing to intake seawaterwith sodium bisulfate (SBS) dosing at the RO portion However, membranes performancedeterioration occurred by oxidation in case of both polyamide and cellulose acetatemembranes, and biofouling has not been solved yet Toray has developed a new methodthat is effective to prevent biofouling on SWRO membranes and verified its effectiveness

at actual plants

First of all, by measuring the viable counts of bacteria at a plant, in case of the ous chlorine/SBS dosing method, it was found that a number of bacteria drasticallyincreased immediately after SBS dosing, as shown in Figure 1.8, and most of these bacteriawere quite different from those found in raw seawater Currently, the addition of SBS tofeed water at relatively high concentration has been used for sterilization of RO membranes.However, when SBS was added to seawater, the pH was just dropped to 6, and most of thebacteria harbored in water were still alive This result indicates that the sterilization ability ofSBS is due to lower pH, and oxygen consumption with SBS only plays a role to repress thecell growth Finally, Toray has developed a new agent, MT-901, which is effective in pre-venting biofouling on RO membranes Adding MT-901 to seawater instead of SBS effec-tively killed bacteria in a few samples of seawater within a short time

continu-Finally, the effect of this method was verified at an SWRO plant In this plant, when feedwater was chlorinated and dechlorinated with SBS continuously and RO membranemodules were treated with SBS intermittently, differentiation pressure of the moduleincreased gradually MT-901 was used for membrane module treatment in place of SBSand the differential pressure decreased within 10 days Moreover, using an intermittentchlorination method was effective to maintain the initial differential pressure with less con-centration of MT-901 (Kallenberg et al., 1999)

& Tobago

1.6 LOW-FOULING RO MEMBRANE FOR

WASTEWATER RECLAMATION

Wastewater reclamation and reuse plants have been constructed and operated around theworld Table 1.10 shows large wastewater reuse plants RO membrane is necessary forwastewater reclamation to make the water quality reusable The largest RO plant is operated

in Kuwait since 2005

For RO membrane modules, stable operation is very important Many organizations, versities, and companies have reported many kinds of operation troubles Fouling, mem-brane deterioration, and hardware problems have mainly caused these troubles, and themajor troubles, which occupy 80%, are fouling problems

uni-As described above, it is important to consider the (1) proper RO membrane elementswith low-fouling property, (2) proper pretreatment technology before the RO membrane,and (3) suitable sterilization methods and cleaning technology (Kurihara et al., 2003)

14 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

The reasons for fouling of RO membrane are reported as consisting of chemical fouling,biological fouling, and scale precipitation.

It is estimated that chemical fouling is caused by the adsorption of organic materials such

as humic substances and surfactants in the feed water or on the membrane surface Humicsubstances have various chemical structures depending on the water origin, such as landwater or seawater, and regions in the world However, it has both hydrophobic groups ofaromatic and linear structure and ionic groups of amino acid and carboxylic acid Thematerial of RO membrane is polyamide with hydrophobic and ionic properties As men-tioned above, chemical fouling depends on hydrophobic interaction and electrostatic inter-action between organic materials in the feed water and membrane surface

On the other hand, in case of biological fouling, the following estimations are reported:(1) microbe adsorption by hydrophobic or electrostatic interaction, (2) propagation ofmicrobe with nutrition in the feed water, and (3) deposition of exhaust material of biologicalmetabolism Case 1 is a reversible phenomenon; however, cases 2 and 3 are irreversiblephenomena, which are difficult to remove by simple chemical cleaning

As a result of R&D activities, Toray has developed low-fouling RO membrane for water reclamation The low-fouling RO membrane has the same level of pure water perme-ability as conventional RO membranes, SU-700 and SUL-G, and also has low-foulingproperty with keeping water permeability against chemical and biological fouling duringthe operation (Yamamura et al., 2002)

waste-The low-fouling property of membranes is evaluated with a nonionic surfactant aqueoussolution Test result shows that, in operation, low-fouling RO membrane has a relativelysmall permeability declaration ratio of 27%, compared with initial pure water permeabilityand shows stable operation On the other hand, conventional fully aromatic polyamidemembranes, SU-700 and SUL-G, show 36 – 47% declaration ratio, even if they showstable operation And concerning the chemical cleaning properties, low-fouling RO mem-brane shows better recovery of permeability after chemical cleaning

To evaluate the fouling property against microbes, adsorption property of a certainhydrophobic microbe and other hydrophilic microbes were measured The hydrophobicmicrobe was severely adsorbed to conventional RO membranes and caused biologicalfouling of RO membranes In case of low-fouling RO membranes, the adsorption property

of the hydrophobic microbe is quite low, which is less than one-tenth of conventional ROmembranes Initial performance of low-fouling RO membrane element TML-20 isdescribed in Table 1.11

A test of wastewater reclamation using low-fouling RO membranes and conventionallow-pressure RO membrane SUL-G10 has been carried out in a wastewater treatment facil-ity in Japan, as shown in Figure 1.9 In this test, secondary effluent was directly filtered byultrafiltration (UF) membrane and permeate was fed to both of the RO membranes In case

Figure 1.9 Water productivity of low-fouling RO compared with conventional RO.

16 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

of the SUL-G membrane, water permeability dropped to 60% of initial permeability in aday due to biological fouling; however, the permeability drop of low-fouling RO TML20was smaller than that of SUL-G and the stable operation has been performed.

The low-fouling RO membrane is strongly required for the stable operation of the water reclamation plant Two large water reclamation and reuse plants have been operated inSingapore and Kuwait, as shown in Figures 1.10, 1.11, and 1.12

waste-1.7 CHLORINE TOLERANCE OF CROSS-LINKED AROMATIC

POLYAMIDE MEMBRANE

Chlorine tolerance is a very important characteristic to design an RO membrane processbecause chlorine dosing to water process is commonly used as a disinfection for micro-organisms Many authors have studied chlorine tolerance of RO membranes as listed

in Table 1.12

In our literature, we studied three kinds of RO membranes: a cellulose acetate metric membrane (SC-3000), a cross-linked N-substituted polyamide composite membrane

Cellulose Acetate

Cross-linked N-substituted Polyamide

Cross-linked Aromatic Polyamide

(UTC-60), and a cross-linked aromatic polyamide composite membrane (UTC-70) usingimmersion and operating test conditions (Uemura and Kurihara, 2003) The degradationwas observed as the increase in both solute and water permeation coefficients, which can

be expressed as functions of a quantity of chlorine concentration to the Xth powertimes the chlorine exposure time It was found that the values of the X are in the range

of 0.5 – 0.7 for cross-linked aromatic composite, 1.2 for cross-linked N-substituted posite, and 1.5 for cellulose acetate asymmetric The value of X seems closely related tothe degradation mechanism In the case of rapid degradation, the degradation might bemainly caused by chlorination reaction, and the value of X should be close to 0.5 Onthe other hand, in the case of slow degradation, the degradation might be caused byoxidation reaction, and value of X should be close to 2 The morphological and structuralchanges due to the chlorination degradation were observed using electron microscopy andelectron spectroscopy for chemical analysis (ESCA) It was clarified that, as the degradationreaction progresses, the membrane thickness is reduced and its looseness and fixed chargedensity are increased The results are summarized in Table 1.13

com-Using the equations in Table 1.13, the membrane performance of both solutepermeation coefficient (DAM/kd) and water permeate coefficient (A) after certain chlorineconcentration (C ) and exposure time (t) can be roughly predicted for each membrane.But some catalytic acceleration reactions, which may be caused by the iron ion and otherheavy-metal ions in water, must be taken into account in actual cases

REFERENCES

Cadotte, J E (1985) Evolution of composite reverse osmosis membrane In Materials Science of Synthetic Membranes ACS Symposium Series 269 American Chemical Society, Washington,

DC, p 273.

Fukunaga, K., Matsukata, M., Ueyama, K., and Kimura, S (1997) Reduction of boron concentration

in water produced by a reverse osmosis sea water desalination unit Membrane 22(4), 211 Fusaoka, Y (1999) Super ultra low pressure composite reverse osmosis membrane elements for brackish water desalination and ultrapure water production Membrane 24(6), 319 – 323 Hiro, A., and Hirose, M (2000) Development of the high boron removal reverse osmosis membrane element for seawater desalination Nitto Giho 40, 36.

Ikeda, T., Fusaoka, Y., Uemura, T., Tonouchi, T., and Fujino, H (1996) Advanced ultra low pressure reverse osmosis membrane elements having a high water flux and a high solute rejection In Preprints of International Congress on Membranes and Membrane Processes, Yokohama, Japan, Aug 18 – 23, p 182.

Kallenberg, K., Jose, P V., Yamamura, H., and Kurihara, M (1999) Brine conversion (BCS) enhances SWRO desalination case histories, operating data, novel design features In Preprints

of IDA World Congress, San Diego, USA, Vol II, Aug 29 – Sept 3, pp 101 – 107.

18 THIN-FILM COMPOSITE MEMBRANES FOR REVERSE OSMOSIS

Kurihara, M., Fusaoka, Y., Sasaki, T., Bairinji, R., and Uemura, T (1994a) Development of cross-linked fully aromatic polyamide ultra-thin composite membranes for seawater desalination Desalination 96, 133.

Kurihara, M., Himeshima, Y., and Uemura, T (1987) In Preprints of ICOM, p 428.

Kurihara, M., Matsuka, N., Fusaoka, Y., and Henmi, M (2003) Newly developed wastewater treatment systems using separation membranes In Proceedings Water Reuse & Desalination Conference, Suntec Singapore, Singapore, Feb 25 – 27.

Kurihara, M., Uemura, T., Himeshima, Y., Ueno, K., and Bairinji, Y (1994b) Development of crosslinked aromatic polyamide composite reverse osmosis membrane Nippon Kagaku Kaishi 1994(2), 97 – 107.

Moch, I (2000) The case for and feasibility of very high recovery sea water reverse osmosis plants.

In Preprints of ADA Conference, Lake Tahoe, USA.

Morgan, P W (1965) Condensation polymers: By interfacial and solution methods In Polymer Reviews, Vol 10 Wiley, New York.

Nakao, S (1996) Sea water desalination process for high recovery of fresh water by reverse osmosis Bull Soc Sea Water Sci Japn 50(6), 406 – 412.

Ohya, H., Suzuki, T., and Nakao, S (1996) Proposal and technological breakthrough of an integrated system for the complete usage of sea water Bull Soc Sea Water Sci Japn 50(6), 389 – 395.

high rejection SWRO membranes Desalination 156, 229.

Rodriguez, M., Ruiz, A F., Chilon, M F., and Rico, D P (2001) Influence of pH in the elimination

of boron by means of reverse osmosis Desalination 140, 145.

Scala, R C., Ciliberti, D F., and Berg, D (1973) Interface condensation desalination membrane U.S Patent 3,744,642.

Taniguchi, M., Fusaoka, Y., Nishikawa, T., and Kurihara, M (2004) Boron removal in RO seawater desalination Desalination 167, 419.

Tomioka, H., Taniguchi, M., Okazaki, M., Goto, S., Uemura, T., and Kurihara, M (2005) Milestone

of high boron rejection seawater RO membrane In Proceedings of IDA World Congress on Desalination and Water Reuse, Singapore, Sept 11 – 14.

Toray (2004) Brochure of TM800 Tokyo, Japan.

Uemura, T., and Kurihara, M (2003) Chlorine resistance of reverse osmosis membranes and changes in membrane structure and performance caused by chlorination degradation Bull Soc Sea Water Sci Jpn 57, 498.

World Health Organization (WHO) (2004) Guidelines for Drinking Water Quality, 3rd ed WHO, Geneva.

Van Heuven, J W (1976) Dynamic membrane U.S Patent 3,996,318.

Yamamura, H., Henmi, M., and Inoue, T (2002) In Development innovative MF and RO membrane for wastewater treatment and reclamation In Proceedings of the 2nd International Conference on Application of Membrane Technology, Beijing, China, Sept 27 – 29.

Yamamura, H., Kurihara, M., and Maeda, K (1994, 1996) Japanese Patent Applications H06-245184 and H08-108048.

&CHAPTER 2

Cellulose Triacetate Membranes for

Reverse Osmosis

A KUMANO and N FUJIWARA

Desalination Membrane Operating Department, Toyobo Co., Ltd., Osaka, Japan

2.1 INTRODUCTION

The reverse osmosis (RO) seawater desalination process has many advantages in the areas

of saving energy, lower capital cost, short startup and shutdown time, short constructionperiod, less installation space, and less total water cost RO technology is becoming thekey technology for obtaining freshwater from the sea, especially in the Middle East.Membrane manufacturers are working to develop membranes offering higher productwater recovery, lower energy consumption, and lower installation costs in order to enablethe RO process to be adopted as the most popular method for supplying freshwateraround the world

The commercialized RO modules consist of cellulose triacetate hollow-fiber type andpolyamide spiral-wound type The cellulose triacetate hollow-fiber RO modules are usedaround the world for seawater desalination mainly because of excellent features such as achlorine tolerance and fouling resistance

This summary describes the history of cellulose triacetate RO membrane, description ofcellulose triacetate hollow-fiber RO modules of Toyobo for seawater desalination, actualoperation results, and recent RO modules of cellulose triacetate including most recentlydeveloped advanced modules

2.2 HISTORY OF CELLULOSE ACETATE MEMBRANE

2.2.1 Development of Loeb-Sourirajan Membrane

The Saline Water Act was enacted in the United States on July 3, 1952 Then, the Office ofSaline Water (OSW) was installed in the Department of the Interior in order to study themethod of obtaining freshwater from seawater and brackish water economically Thiseffort accelerated development of RO membranes The RO process was proposed as one

Advanced Membrane Technology and Applications Edited by Norman N Li, Anthony G Fane,

W S Winston Ho, and T Matsuura

Copyright # 2008 John Wiley & Sons, Inc.

21

of the methods of desalination by Reid of Florida University in the beginning of 1953.Workers at Florida University studied various commercial polymer films in 1957 andannounced a cellulose diacetate film as the outstanding semipermeable membrane inwhich salt rejection was 96% or more However, the permeability of water was verysmall After that, Loeb and Sourirajan of UCLA succeeded in developing a method ofmanufacturing a new asymmetric membrane in 1960 The obtained membrane had highpermeability and consisted of a heat-treated cellulose diacetate asymmetric membrane.These improvements in advanced performance of a membrane led to a practical application

of the RO membrane module that was promoted (Breton, 1957; Reid and Breton, 1959;Loeb and Sourirajan, 1964)

2.2.2 Development of Commercial Cellulose Acetate

Membrane Modules

Gulf General Atomic was funded by OSW and developed a spiral – wound-type module.Moreover, the company applied for the patent of the basic structure in 1964 In thepatent, the example that used the cellulose diacetate membrane of Loeb and Sourirajanwas indicated (Westmoreland, 1968) The improvement was performed after that in eachcompany, and the spiral-wound-type module using a cellulose acetate membrane was put

on the market by many companies, such as UOP, Hydranautics, Envirogenics, TorayIndustries, and Daicel

As for tubular-type modules, from the 1960s, various models of tubular-type moduleswere developed and put on the market by many companies The RO plant using themodule that Loeb and others developed worked in 1965 (McCutchan and Johnson, 1970)

A hollow-fiber-type module was developed and a fundamental patent was filed by DowChemical in 1960 An RO module using the cellulose triacetate hollow fiber is indicatedthere (Mahon, 1966) A significant portion of research and development at DowChemical was carried out based on its research contract with OSW, and the developmentresults of the RO module for brackish water was published in 1970 and for seawater in

1974 The RO module using cellulose triacetate hollow fiber for brackish water wasmarketed in 1974 (Dance et al., 1971; Ammons and Mahon, 1974)

Research and development of the hollow-fiber-type module using a cellulose acetatemembrane was conducted by Monsanto, Toyobo, and others, in addition to Dow Chemical.Toyobo announced an RO module for one-pass desalination of seawater that used the cellulosetriacetate hollow-fiber membrane module in 1979 (Orofino, 1970; Ukai et al., 1980)

2.3 TOYOBO RO MODULE FOR SEAWATER DESALINATION

2.3.1 Hollow-Fiber RO Membrane for Seawater Desalination

Seawater desalination by reverse osmosis is the most effective method for the production offreshwater among various desalination technologies Hollow-fiber RO membranes and flat-sheet membranes have been developed for brackish water and seawater desalination by atwo-pass process since 1976 (Ohya, 1976) In spite of a satisfactory result of two-pass sea-water desalination processes, the one-pass process has the advantages of simple andcompact plant, simple operation, easy maintenance, and the lowest energy consumption.Although several one-pass seawater desalination systems by reverse osmosis have been