Table Of ContentMicrofiltration and
Ultrafiltration Membranes
for Drinking Water
MANUAL OF WATER SUPPLY PRACTICES-M53, First Edition
AWWA MANUAL M53
First Edition
American Water Works
Association
Science and Technology
AWWA unites the entire water community by developing and distributing authoritative scientific and technological
knowledge. Through its members, AWWA develops industry standards for products and processes that advance public
health and safety. AWWA also provides quality improvement programs for water and wastewater utilities.
Copyright (C) 2005 American Water Works Association All Rights Reserved
MANUAL OF WATER SUPPLY PRACTICES-M53, First Edition
Microfil tration and UI trafil t rat ion Membranes for Drinking Water
Copyright 0 2005 American Water Works Association
All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any
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Project Manager/Senior Technical Editor: Melissa Christensen
Produced by Glacier Publishing Services, Inc.
Library of Congress Cataloging-in-PublicationD ata
Microfiltration and ultrafiltration membranes for drinking water.--1st ed.
p. cm. -- (AWWA manual ; M53)
Includes bibliographical references and index.
ISBN 1-58321-360-0
1. Water--Purification--Membrane filtration--Evaluation. 2. Ultrafiltration. I. American Water
Works Association. 11. Series.
TD491.A49 no. M53
[TD442.51
628.1 s--dc22
[628.1'641
2004062318
Printed in the United States of America
American Water Works Association
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ISBN 1-58321-360-0
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Copyright (C) 2005 American Water Works Association All Rights Reserved
Contents
List of Figures, vii
List of Tables, xi
Foreword, xv
Acknowledgments, xvii
Table of Equivalents, xxi
. . . . . . . . . . . . . . . . . . .
Chapter 1 Introduction 1
Introduction, 1
Process Overview, 1
Growth of Membrane Technology, 3
Historical Overview of MF and UF, 4
Current Status, 5
Future Trends, 6
References, 6
. . . . . . . . . . . . . . . . . .
Chapter 2 Water Quality 7
Introduction, 7
Particle Removal, 8
Microbial Control, 10
Organic Control, 13
Inorganic Control, 18
References, 20
Appendix 2A, Turbidity Results for MF and UF Membrane Systems, 26
Appendex 2B, Particle Counting Results for MF and UF Membrane
Systems, 30
Appendex 2C, DOC and DBP Precursor Results for MF and UF Membrane
Systems, 32
. . . . . . . . . . .
Chapter 3 Membrane Science and Theory 35
Water Permeation Across Clean MF/UF Membranes, 35
Reductions in Membrane Productivity, 39
Summary, 46
Acknowledgments, 47
Bibliography, 47
. . . . . . . . . . . . . . . .
Chapter 4 System Concepts 51
Introduction, 51
Membrane Materials and Geometries, 51
Process Design, 55
MF and UF Operation Concepts, 56
Membrane Backwashing and Pre- Posttreatment, 58
Chemical Cleaning, 60
Membrane Integrity Testing, 61
References, 64
...
111
Copyright (C) 2005 American Water Works Association All Rights Reserved
Chapter 5 Microfiltration and Ultrafiltration
. . . . . . . . . . . . . . . . .
Membrane Manufacturers 65
Introduction, 65
Purpose of This Chapter, 66
Hydranautics, 67
Koch Membrane Systems Inc., 70
Norit Americas Inc., 73
Aquasource, 79
Pall Corporation, 84
USF Memcor, 90
Zenon Environmental Inc., 95
. . . . . . . . . . . . . .
Chapter 6 Membrane Applications 101
Membrane Filtration for Turbidity and Microbial Removal in
Early Plants, 101
Integrated Process Applications Emerge as the Predominant
Treatment Approach, 102
Preliminary Membrane Treatment, 103
Intermediate Membrane Treatment, 104
Final Membrane Treatment, 105
Summary, 110
References, 110
Appendix 6A, Case Study: San Jose Water Company, Saratoga
Water Treatment Plant-Microfiltration of Variable
Quality River Water, 112
Appendix 6B, Case Study: Manitowoc Public Utilities-Microfiltration
of Lake Water, 115
Appendix 6C, Case Study: Coliban Water, Sandhurst Water
Treatment Plant-Submerged Microfiltration of Reservoir Water, 119
Appendix 6D, Case Study: Barrow Utilities Electric Cooperative
1nc.-Microfiltratiod Nanofiltration Dual-Membrane Plant, 123
Appendix 6E, Case Study: Brazos River Authority, Lake Granbury
Surface Water Advanced Treatment System-UltrafiltratiodReverse
Osmosis Integrated Membrane System, 127
Appendix 6F, Case Study: Seekonk, Mass.-Iron and Manganese
Removal Plant, 132
Appendix 6G, Case Study: Fallon Paiute-Shoshone Tribe-
CoagulatiodMicrofiltration Facility for Arsenic Removal, 135
Appendix 6H, Case Study: Pittsburgh, Pa., Facility-Polishing of
Finished Water Reservoir Water Using Microfiltration, 139
Appendix 61, Case Study: Lyonnaise Water, Bernay Water Treatment
Plant, Bernay, France, 142
. . . . . . . . .
Chapter 7 Pilot Testing of Membrane Systems. 147
Introduction, 147
Define the Project: Membrane System Screening and
Process Integration, 148
Pilot Testing Scheduling Criteria, 151
Pilot Testing Protocol, 153
Sample Results and Organization of Pilot Study, 161
Bibliography, 164
iv
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. . . . . . . . .
Chapter 8 Membrane System Design Concepts 165
Overall System Design Approach, 165
Site-Specific Issues, 166
Membrane-Specific Issues, 171
Membrane System Design Issues, 176
Reference, 186
. . . . . . . . . . . . . . . . . . .
Chapter 9 Operations 187
Introduction, 187
Differences Between MF/UF and Conventional Granular
Media Filtration, 188
How to Control a MFWF Plant, 189
Data Collection and Recordkeeping, 191
Process Monitoring, 191
Special Operating Considerations for Various System Designs, 193
Maintaining Productivity, 194
Maintaining Filtrate Quality, 198
Troubleshooting and Proactive Ideas, 201
Training, 202
Safety, 202
Bibliography, 203
Chapter 10 Cost of Microfiltration and Ultrafiltration
. . . . . . . . . . . . . . . . . . .
Membrane Systems 205
Project Management and Administrative Costs, 206
Membrane Procurement Costs, 207
Membrane System Capital Cost Considerations, 208
Additional Capital Cost Considerations, 209
Operational Costs, 210
Generalized Membrane Equipment Costs, 211
Generalized Construction Costs, 212
Operations and Maintenance Costs, 214
Summary, 215
. . . . . . . . . .
Chapter 11 Residuals and Their Management 217
Microfiltratioflltrafiltration Residuals, 2 17
MFWF Residuals Management, 222
Groundwater Discharge, 223
Location a Factor in Choosing Disposal Methods, 225
Backwash Disposal and Treatment Methods, 225
Chemicals a Factor in Handling Cleaning Solutions, 227
Summary, 228
References, 229
. .
Chapter 12 Future Trends in Low-Pressure Membrane Filtration 23 1
System Capacity, 232
Standardization, 233
Membrane Materials and Modules, 234
Technology Advancements, 235
Regulatory Issues, 236
V
Copyright (C) 2005 American Water Works Association All Rights Reserved
Applications, 237
Costs, 238
Overcoming Impediments to Implementation, 239
Summary, 240
References, 240
Glossary, 241
Index, 247
Copyright (C) 2005 American Water Works Association All Rights Reserved
rn
AWWA MANUAL
1
Chapter
Introduction
Author:
James C. Vickers
Reviewer:
Scott Freeman
INTRODUCTION
Since the early 199Os, there has been rapid growth in the use of low-pressure hollow
fiber microfiltration (MF) and ultrafiltration (UF) membrane processes for the produc-
tion of drinking water. This growth has been propagated by the changes in the regula-
tory requirements of the Safe Drinking Water Act, beginning with the Surface Water
Treatment Rule (SWTR), that require lower filtered water turbidity and removal of
disinfectant-tolerant microorganisms, such as Giardia and Cryptosporidium.
In wastewater reclamation, MF and UF have enjoyed a similar level of growth,
where they have essentially replaced lime softening and filtration as the preferred
methods of pretreatment prior to reverse osmosis (RO) for advanced reclamation
projects.
The intent of this manual is to describe MF and UF system technology. These
treatment techniques have gained rapid acceptance as processes that provide a reli-
able and very high level of particle, turbidity, and microorganism removal.
PROCESS OVERVIEW
The following graph (Figure 1-1)i s commonly used to illustrate the difference between
conventional and membrane filtration processes. When compared, there are two dis-
tinctions that become important. The first is that MF and UF processes achieve sepa-
ration through physical removal, essentially size exclusion, and unlike conventional
coagulation-based processes do not require physiochemical treatment prior to media
filtration to achieve the desired level of particle removal. The second distinction of
membrane filtration is that the pore size is highly uniform and, therefore, capable of
very high, or “absolute,” removal of a targeted particle size or microorganism.
In comparison to the established desalting membrane processes RO and nano-
filtration [NF]), the growth of MF and UF as treatment processes has followed a
1
Copyright (C) 2005 American Water Works Association All Rights Reserved
2 MICROFILTRATION AND ULTRAFILTRATION MEMBRANES
100 1,000 10,000 100,000 500,000 APPROXIMATE MOLECULAR
I I I I I WEIGHT
0.001 u 0.01 u 0.lu 1 .ou 1 ou 1 oou 1 .ooou
1 I I 1 I I I
Dissolved Organics Sand
Bacteria
Viruses Cvsts
Microfiltration
Reverse Osmosis
~~ ~~
Figure 1- 1 Basic diagram of mass transport in a membrane
substantially different path. Whereas the concepts and fundamentals of RO and NF
technologies were established prior to the introduction into the municipal water treat-
ment industry, the proliferation of MF and UF system technology has been character-
ized by numerous manufacturers that offer proprietary membrane system technology.
These membrane systems incorporate proprietary design features that vary consider-
ably and are not interchangeable, although this may change as the industry evolves.
However, a common feature of most all of the currently available MF and UF
membrane equipment is that hollow fibers are used to perform the separation. The
hollow fiber is particularly well suited for use as a separation media because (1)i t has
a high surface to volume ratio, and (2) it exhibits bi-directional strength. These prop-
erties allow for backwashing with water, air, or a combination of both. Hollow fibers
are flexible in their configuration and can be operated in the outside-in or inside-out
manner of flow and may use either pressure or vacuum as the driving force across the
membrane. It is the variations in membrane materials and the variety of ways that
the membrane can be configured and operated that facilitates the use of proprietary
designs.
Although the system concepts, membranes, and nomenclature vary considerably
from manufacturer to manufacturer, a key aspect that has contributed to the success
of this technology is the ability to test and verify the integrity of the membrane. Man-
ufacturers have adapted integrity testing concepts from cartridge-based filtration pro-
cesses to their hollow fiber counterparts. Integrity testing provides the user with the
ability to verify the removal performance of the membrane process and facilitate the
diagnosis of malfunction and repair of membranes in the event of an integrity failure.
Although some have questioned the appropriateness of this aspect of the regulation,
the proposed Long-Term 2 Enhanced Surface Water Treatment Rule (LTBESWTR)
recognizes the importance of integrity testing (USEPA 2003) and incorporates direct
integrity testing as a component that will allow a membrane process to receive higher
log removal credits.
Copyright (C) 2005 American Water Works Association All Rights Reserved
INTRODUCTION 3
1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Installation Year
*Projected based on manufacturer provided information
Figure 1-2 The growth in the use of membrane technology
GROWTH OF MEMBRANE TECHNOLOGY
The following graph (Figure 1-2) illustrates the growth in the use of membrane tech-
nology (USEPA 2001). This trend is continuing an exponential increase as numerous
membrane facilities ranging from of 25 to 100 mgd in capacity are either planned, in
design, or in operation.
The fundamental reasons for this growth can be categorized as follows:
Regulatory-As evidenced by the SWTR and the subsequent iterations that
require a higher level of turbidity and particle removal, MF and UF treatment
processes can be used to consistently obtain treatment objectives.
Broader applicability-MF and UF treatment processes are particulate filters
and unlike NF and RO do not remove dissolved constituents. This aspect of
treatment makes them more applicable for use as a replacement for conven-
tional filters, and thus MF and UF have exhibited widespread geographic
applications.
Cost-Since the early 199Os, the capital cost of MF and UF treatments have
decreased as economies of scale, innovation, and competitive market forces
influence projects. Comparatively, an MF or UF facility is approximately one
half to one third the cost of an NF or RO facility and in many circumstances is
cost competitive with most conventional alternatives. In addition, the imple-
mentation of innovative backwash or cleaning strategies has reduced opera-
tional cost. Many MF and UF membrane systems operate at pressure
differentials of less than 15 psi.
Operational flexibility-MF and UF treatment processes are highly flexible
and can be used in conjunction with other treatment processes to achieve
additional removal. Thus, as further detailed in chapter 6, there has been cre-
ativity in the application of the MF and UF membrane processes to achieve
Copyright (C) 2005 American Water Works Association All Rights Reserved
4 MICROFILTRATION AND ULTRAFILTRATION MEMBRANES
additional treatment objectives. In addition, membrane systems can be easier
to operate, as the filtrate quality is not affected by process chemistry or varia-
tions in flow. Operations and maintenance activities are discussed in chapter 9.
To better understand some of the underlying considerations of this growth, the
following section provides a historical overview of this technology.
HISTORICAL OVERVIEW OF MF AND UF
In the mid- to late 1980s, investigators began to consider the use of membrane filtra-
tion (MF and UF) as a method to produce high-quality drinking water. At that time,
membrane filtration processes were limited to small volume, semi-batch operations,
such as wine and juice filtration and industrial waste treatment. Membrane systems
of this type generally relied on inside-out flow patterns and high crossflow velocity to
maximize membrane flux and minimize membrane fouling.
Initial efforts to commercialize MF/UF for drinking water treatment were pio-
neered by Lyonnaise des Eaux (Aquasource; Jacangelo et al. 1989) and Memtec (Mem-
cor; Olivieri et al. 1991a). The Aquasource technology was developed in France for
groundwater treatment and virus removal, where chlorine use is disfavored. The Aus-
tralian Memcor technology was originally developed for industrial use in a crossflow
configuration with an innovative gas backwash. Its applicability to water treatment
was initially established by Hibler (1987) and later by Olivieri et al. (1991b) who were
funded by Memcor to determine if the membrane product could be applied to the
treatment of drinking water and secondary effluent.
Memcor established that CMF, their abbreviation for crossflow microfiltration,
could be operated as a dead-end filter, relying on the gas-backwash alone to maintain
productivity. Pilot systems were established at local drinking water and wastewater
locations to demonstrate that the product would be operationally viable in a municipal
environment. These findings were reported at the American Water Works Association
(AWWA) 1991 Membrane Technology Conference, which also described the initial
efforts using CMF to determine if coagulant-enhanced microfiltration could be used to
improve filtrate quality and reduce disinfection by-product (DBP) formation potential
(Olivieri et al. 1991b). The second aspect of the Memcor technology that was of partic-
ular note was the incorporation of a membrane test that could be used to confirm hol-
low fiber integrity.
Awareness and interest in MF/UF gained further momentum through projects
funded by the Awwa Research Foundation with Jacangelo et al. (1992) and research
performed by Clark at the University of Illinois Urbana-Champaign (Heneghan and
Clark 1991), and Reiss and Taylor at the University of Central Florida (Reiss and Tay-
lor 1991). Wiesner of Rice University established that MF/UF could be considered
cost-effective at capacities of 5 mgd (Wiesner et al. 1994). About this time, Olivieri
joined Memcor on a full-time basis and began to develop pilot projects with consulting
engineers and municipalities.
Memcor’s piloting efforts culminated in the first significant MF facility, the
Saratoga, Calif., location of the San Jose Water Company in early 1993 (Yo0 et al.
1995). The facility, rated at 3.6 mgd, was roughly 4.5 times larger than any existing
Memcor installation. The Saratoga Water Treatment Plant was typical of most early
treatment facilities installed by Memcor. Most, if not all, were facilities required by
the SWTR, which was passed in 1989 and became effective in 1993. These facilities
could be characterized as generally having unfiltered water, with low total organic
carbon concentrations and DBP formation potential, and with periodic excursions of
turbidity. This type of facility was ideal for MF/UF technology, and Memcor attained
commercial success. Many facilities including those located at Kenosha, Wisc., and
Marquette, Mich., fit this basic profile.
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