GE-1009.001GE-1009.001
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`GE-1009.001
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`

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`GE-1009.002
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`

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`GE-1009.003
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`

`
`ULTRAFILTRATION and MICROFILTRATION
`HANDBOOK
`
`GE-1009.004
`
`

`
`HOW TO ORDER THIS BOOK
`
`BY PHONE: 800-233-9936 or 717-291-5609, 8AM-5PM Eastern Time
`
`BY FAX: 717-295-4538
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`
`GE-1009.005
`
`

`
`H ANDBOOK
`
`University of Illinois
`Urbana, Illinois, USA
`
`TECHNOMIC
`~PUBLISHING CO., INC~
`
`[ ~ANCASTER ¯ BASE~[,
`
`GE-1009.006
`
`

`
`Ultrafiltration and Microfiltration Handbook
`aTECHNOMIC ~ublication
`
`Published in the Western Hemisphere by
`Technomic Publishing Company, Inc.
`851 New Holland Avenue, Box 3535
`Lancaster, Pennsylvania 17604 U.S.A.
`
`Distributed in the Rest of the Worm by
`Technomic Publishing AG
`Missionsstrasse 44
`CH-4055 Basel, Switzerland
`
`Copyright © ~98 by Technomic Publishing Company, Inc.
`All fights reserved
`
`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, or otherwise,
`without the prior written permission of the publisher.
`
`Printed in the United States of America
`
`10987654321
`
`Main entry under title:
`Ultrafiltmtion and Micmfiltration Handbook
`
`A Technomic Publishing Company book
`Bibliography: p.
`Includes index p. 517
`
`Library of Congress Catalog Card No. 97-62251
`ISBN No. 1-56676-598-6
`
`GE-1009.007
`
`

`
`TABLE OF CONTENTS
`
`Preface
`
`List of Abbreviations
`
`1.Bo
`
`1. INTRODUCTION
`1.A. Definition and Classification of Membrane
`Separation Processes ...................................
`1
`Historical Developments ................................ 9
`Physical Chemistry of Membrane Separations ............... 13
`1.C.1. Chemical Potential and Osmosis 13
`1.C.2. Vapor Pressure 16
`1.C.3. Osmotic Pressure and Chemical Potential 16
`References
`
`2. MEMBRANE CHEMISTRY, STRUCTURE, AND FUNCTION
`31
`2.A. Definitions and Classification ............................ 31
`2.A.1. Depth Versus Screen Filters 31
`2.A.2. Microporous Versus Asymmetric Membranes 32
`2.B. General Methods of Membrane Manufacture ..... " ........... 38
`2.B.1. Phase-Inversion Process of Membrane Manufacture 39
`2.C. Polymers Used in Membrane Manufacture ................. 41
`2.C. 1. Cellulose Acetate 42
`2.C.2. Polyamide Membranes 45
`2.C.3. Polysulfone Membranes 45
`2.C.4. Other Polymeric Materials ’50
`2.D. Composite Membranes ................................ : 53
`2.E.
`Inorganic Membranes .................................. 57
`2.E.1. Properties of Inorganic Membranes 65
`References
`
`................................................... 9
`
`3. MEMBRANE PROPERTIES
`71
`3.A. Pore Size ............................................ 71
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`GE-1009.008
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`vi
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`Table of Contents
`
`3.A.1. Bubble Point and Pressure Techniques 72
`3.A.2. Direct Microscopic Observation 78
`3.B. Predicting Flux from Pore Statistics ....................... 83
`3.B.1. Example 84
`3.C. Passage (Challenge) Tests ............................... 85
`3.C.1. Microf!ltrationMembranes 85
`3.C.2. Ultrafiltration Membranes 89
`3.D. Factors Affecting Retentivity of Membranes ................ 96
`3.D.1.
`Size of the Molecule 96
`Shape of the Molecule 98
`3.D.2.
`Membrane Material 98
`3.D.3.
`3.D.4.
`Presence of Other Solutes 100
`Operating Parameters 104
`3.D.5.
`Lot-to-Lot Variability 105
`3.D.6.
`Membrane Configuration 106
`3.D.7.
`Fouling and Adsorption Effects 106
`3.D.8.
`The Microenvironment 107
`3.D.9.
`References .................................................. 111
`113
`4. PERFORMANCE AND ENGINEERING MODELS
`4.A. The Velocity Boundary Layer ........................... 113
`4.B. The Concentration Boundary Layer ...................... 114
`4.C. Models for Predicting Flux: The Pressure-Controlled
`Region .............................................. 116
`4.D. Concentration Polarization ............................. 120
`4.E. Mass Transfer (Film Theory) Model ...................... 124
`4.E.1. Determining the Mass Transfer Coefficient 128
`4.E.2. Example 130
`4.E The Resistance Model ................................. 132
`4.G. Osmotic Pressure Model for Limiting Flux ................ 135
`4.H. Factors Affecting Flux: Operating Parameters .............. 136
`4.H.1. Feed Concentration 136
`4.H.2. Temperature 146
`4.H.3. Flow Rate and Turbulence 147
`4.1. Physical Properties of Liquid Streams .................... 155
`4.1.1. Density 157
`4.I.2. Viscosity 158
`4.I.3. Diffusion Coefficients 159
`4.J. Experiment versus Theory: The "Flux Paradox" . ........... 162
`4.K. Design Factors Affecting Flux .......................... 165
`References .................................................. 167
`171
`5. EQUIPMENT
`5.A. Laboratory-Scale Devices .............................. 171
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`Table of Contents
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`vii
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`5.B. Industrial Equipment .................................. 178
`5.B.1. Tubular Modules 178
`5.B.2. Hollow Fibers 190
`5.B.3. Plate Units 205
`5.B.4. Spiral-Wound 211
`5.C. Special Modules ..................................... 226
`5.C.1. Rotary Modules 227
`5.C.2. Vibrating Modules 230
`5.C.3. Dean Vortices 233
`5.D. Summary ........................................... 234
`References .................................................. 235
`
`237
`6. FOULING AND CLEANING
`6.A. Characteristics of Fouling .............................. 237
`6.A.1. WaterFlux 239
`6.B. Consequences of Fouling .............................. 242
`6.C. Mathematical Models of Fouling ........................ 243
`6.D. Factors Affecting Fouling .............................. 245
`6.D.1. Membrane Properties 245
`6.D.2. Solute Properties 256
`6.D.3. Process Engineering 263
`6.E. Flux Enhancement .................................... 267
`6.E.1. Turbulence Promoters/Inserts/Baffles 267
`6.E.2. Backflushing, -pulsing, -shocking, and-washing 267
`6.E.3. Uniform Transmembrane Pressure/Co-Current
`Permeate Flow 2{57
`6.E.4. PermeateBackpressure 271
`Intermittent Jets 274
`6.E.5.
`6.E.6. Pulsatile Flow 274
`6.E.7. Electrical Methods 274
`6.E Summary: Membrane Fouling .......................... 275
`6.G. Cleaning Membranes ................................. 276
`Important Factors During Cleaning 278
`6.G.1.
`6.G.2. Typical Foulants and Soils 281
`6.G.3. Cleaning Chemicals 282
`6.G.4. Sanitizers 285
`References .................................................. 288
`
`7. PROCESS DESIGN
`7.A. Physics of the Membrane Process ........................ 293
`7.A. 1. Example 294
`7.B. Modes of Operation ................................... 298
`7.B.1. Discontinuous Diafiltration 299
`7.B.2. Continuous Diafiltration 302
`
`293
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`GE-1009.010
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`viii
`
`Table of Contents
`
`7.B.3. Dialysis Ultrafiltration 305
`7.C. Batch Versus Continuous Operation ...................... 307
`7.C.1. Batch Operation 308
`7.C.2. Single Pass 309
`7.C.3. Feed-and-Bleed 309
`7.C.4. Multistage Operations 311
`7.C.5. Example 313
`7.C.6. ControlMethods 316
`7.D. Minimum Process Time ............................... 318
`7.E. Fractionation of Macromolecules ........................ 324
`7.E Energy Requirements ................................. 326
`7.El. Example 330
`7.G. Costs and Process Economics ........................... 334
`7.G.1. Arrays and Configurations 334
`7.G.2. System Cost 339
`7.H. Summary ........................................... 342
`References .................................................. 343
`8. APPLICATIONS
`345
`8.A.
`Electrocoat Paint ..................................... 345
`8.B.
`The Dairy Industry ................................... 349
`8.B.1. Fluid Milk and Fermented Products 352
`8.B.2. Cheese Manufacture 353
`8.B.3. Milk Microfiltration 360
`8.B.4. Cheese Whey Ultrafiltration 363
`8.B.5. Microfiltration of Whey 367
`8.C. Water Treatment ..................................... 369
`8.C.1. Process Water 370
`8.C.2. Drinking Water 373
`8.D. Wastewaters ......................................... 375
`8.D.1. Oily Wastewater 376
`8.D.2. Stillage from Bioethanol Plants 382
`8.D.3. Caustic and Acid Recovery 384
`8.D.4. Brine Recovery 384
`8.D.5. Printing Ink 385
`8.D.6. Laundry Wastewater 386
`8.D.7. Micellar-Enhanced Ultrafiltration 386
`8.E. Textile Industry ...................................... 388
`8.E Latex Emulsions ..................................... 391
`8.G. Pulp and Paper Industry ............................... 393
`8.H. Tanning and Leather Industries .......................... 397
`8.1.
`Sugar Refining ....................................... 399
`Soybean and Other Vegetable Proteins .................... 402
`8.J.
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`GE-1009.011
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`Table of Contents
`
`ix
`
`8.Ko
`
`8.L.
`
`8.M.
`
`Vegetable Oils
`....................................... 406
`8.K.1.
`Degumming 408
`8.K.2.
`Deacidification 408
`8.K.3.
`Bleaching 411
`8.K.4.
`Removal of Metals 411
`8.K.5.
`Dewaxing 412
`8.K.6.
`Clarifying Frying Oils 413
`Corn and Other Grains
`................................ 413
`8.L.1.
`Dextrose Clarification 415
`8.L.2.
`Protein Processing 418
`Animal
`Products ..................................... 420
`8.M.1.
`Red Meat 420
`8.M.2.
`Gelatin 421
`8.M.3.
`Egg Processing 425
`8.M.4.
`Fish Processing 427
`8.M.5.
`Poultry Industry 428
`8.N. Biotechnology Applications ............................ 429
`8.N. 1. Separation and Harvesting of Microbial Cells 432
`8.N.2. Enzyme Recovery 439
`8.N.3. Affinity Ultrafiltration 440
`8.N.4. Membrane Bioreactors 443
`8.0. Fruit Juices and Extracts ...............................
`470
`8.P. Alcoholic Beverages .................................. 480
`8.P.1. Wine 480
`8.P.2. Beer 483
`References .................................................. 84
`APPENDIX A Manufacturers and Suppliers of Membrane Systems... 495
`APPENDIX B Conversion Factors ............................. 503
`APPENDIX C Books and General References .................... 507
`Glossary of Terms
`
`Index
`
`About the Author
`
`517
`
`527
`
`511
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`GE-1009.012
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`

`
`CHAPTER 5
`
`Equipment
`
`Industrial users of membrane technology have a choice of six basic designs of
`equipment: (1) tubular, with inner channel diameters >4 mm; (2) hollow fibers,
`with inner diameters of 0.2-3 mm; (3) plate units; (5) spiral-wound modules;
`(5) pleated-sheet cartridges; and (6) rotary modules. In some cases, designers
`have attempted to use sound hydrodynamic principles and complex mathe-
`matical models to optimize the performance of their hardware. Their main
`constraints have been economics, manufacturing techniques, or sometimes tra-
`dition. In this chapter we will describe the various types of equipment available
`in the market and focus on those aspects that distinguish one type from an-
`other. No attempt has been made to exhaustively cover all equipment made by
`all manufacturers. Any descriptions, photographs, data, and specifications of a
`particular membrane module are mentioned here only to illustrate features of a
`particular design. Mention of a brand name should not be construed as an en-
`dorsement of that product, nor does it necessarily imply that those not mentioned
`are unsuitable for a particular membrane application. Equipment development
`has been done almost exclusively by the manufacturers themselves. Thus, this
`chapter is based on information provided by equipment manufacturers, as well
`as the author’s own experiences with some of the equipment. A partial listing
`of manufacturers and their addresses is given in Appendix A.
`Pleated sheet cartridges (Figure 5.1) are used mostly for dead-end microfil-
`tration. They work well in their intended applications, and they are relatively
`uncomplicated in their design and use (Porter 1990; Shucosky 1988; Swiezbin
`et al. 1996). The focus here is on cross-flow designs, and thus pleated cartridges
`are not discussed.
`
`5oAo
`LABORATORY-SCALEDEVICES
`
`Laboratory (bench-top) devices provide a means of rapidly screening mem-
`branes for a particular application or for handling small volumes. The simplest
`and smallest of the membrane separation units is shown in Figure 5.2. These
`are essentially dead-end filtration devices (as defined in Figure 4.4) to be used
`
`!7!
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`GE-1009.013
`
`

`
`Figure 5.1. Typical direct flow dead-end pleated sheet membrane cartridge filter
`(Source: Pall Corporation, with permission).
`
`in laboratory centrifuges, with the driving force being provided by centrifugal
`forces. The Centrifree concentrator from Amicon and the Microsep from Pall
`Filtron are for volumes of 0.15-3.5 mL; similar devices are available for vol-
`umes up to 15 mL. The sample to be ultrafiltered is placed in the upper chamber,
`which contains the membrane, and the whole unit is placed in a fixed-angle rotor
`centrifuge. Spin times vary from 15-60 min for 10,000 to 100,000 molecular
`weight cut-off (MWCO) membranes and up to 2 h with 3000 MWCO mem-
`branes for desalting biological samples. The Centriflo membrane cone shown in
`Figure 5.2 is for samples up to 7 mL and is presently available with 25,000 and
`50,000 MWCO membranes. The Centrisart devices from Sartorius are similar,
`with the membrane filter insert made of cellulose acetate or polyethersulfone
`in a choice of pore sizes. The rigid outer tube may be made of polypropylene.
`Smaller devices such as the Microcon and Micropure units from Amicon and the
`Nanosep from Pall Filtron are also available for samples of 50-500/zL. Cost of
`
`GE-1009.014
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`Laboratory-Scale Devices
`
`173
`
`Figure5.2. Laboratory-scale UF/MF equipment for extremely smaH volume samples:
`left: "Microsep" micropartition device from Pall Filtron for volumes of 0.5-3.5 mL;
`right: Amicon’s "Centriflo " membrane cone shown being inserted into a 50-mL cen-
`trifuge tube. The sample to be ultrafiltered is placed in the cone. After centrifugation,
`the permeate collects in the centrifuge tube and the retentate is retained in the cone.
`
`these centrifugal devices is $0.90 each for Micropure 0.22-/z units, $1.50 each
`for the Nanosep, $2.10-$2.30 each for Centricon and Macrosep concentrators,
`and $9 each for Centriflo cones (all U.S. prices in 1995).
`The major use for these small dead-end units is for rapid ultrafiltration (UF)
`or microfiltration (MF) of small volumes that may be used in clinical and an-
`alytical applications, for in vitro diagnostic use and for determining ligand-
`macromolecule binding parameters as described elsewhere (Cheryan 1986;
`Cheryan and Saeed 1989). However, being dead-end devices, there is no way to
`control concentration polarization, andthus they are best used with relatively
`clean and dilute samples. No flux data can be obtained with these devices.
`Larger laboratory devices are shown in Figures 5.3 and 5.4. These are also
`dead-end cells but have a means for controlling polarization by agitation of
`the fluid. This is done with a magnetic stirring bar placed as close as possible
`to the membrane surface. These are commercially available (e.g., from Ami-
`con/Millipore, Pall Filtron) with volumes of 25 mL to 2 L; the common sizes of
`100-400 mL cost $400-$800 for the cell assembly alone (shown in Figure 5.3),
`depending on the size and the manufacturer. Figure 5.4 shows how these cells
`are used. The cell is placed on a magnetic stirrer, and a pressure source such
`as a gas cylinder is connected to the cell. If diafiltration or continuous feed is
`needed, a reservoir is placed between the gas cylinder and the cell via a three-
`way valve. The cell assembly can be placed in a water bath and then placed on
`top of the magnetic stirrer if necessary. As will be seen later, agitation results
`in a vast improvement in polarization control, and flux is much higher.
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`174
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`EQUIPMENT
`
`Inlet
`
`Pressure
`Relie~ Valve
`
`Stirring
`Bar
`
`Beaker
`Oesign
`
`Suppo~l
`
`Filtrate __
`Oullet
`
`Wrap-Around
`Oamp
`
`Figure 5.3. Schematic of a typical dead-end stirred cell showing its individual com-
`ponents (Source: Amicon catalog, with permission).
`
`One further step up the polarization control ladder are the thin-channel de-
`vices (Figure 5.5), where the retentate is pumped through narrow channels or
`slits on top of the membrane at high shear rates using a peristaltic pump. The re-
`tentate is returned to the feed reservoir. Pressure still has to be provided with an
`external source such as a gas cylinder. The TCF-10"system shown in Figure 5.5
`has a reservoir volume of 600 mL and costs about $2500. It can also be adapted
`for diafiltration.
`For even larger volumes (1-10 L) and more realistic performance data, the
`devices shown in Figure 5.6 can be used. The basic reservoir-peristaltic pump
`combination can be connected either to small spiral-wound cartridges (16 cm
`long, 0.09 m2) or to hollow fiber cartridges (e.g., H1 series, 20 cm long, 0.03-
`0.06 m2), depending on the fittings chosen. The hardware for the units shown
`in Figure 5.6 costs $3100o3500. The S1 spiral-wound cartridge from Amicon
`Corporation, available with YM membranes of 1000-100,000 MWCO, is $330
`
`GE-1009.016
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`

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`Laboratory-Scale Devices
`
`175
`
`Figure 5.4. Top: Flow diagram for the use of a dead-end stirred cell (I = pressure
`gauge; 2 = pressure release valve; 3 = three-way valve; 4 = reservoir for feed;
`5 = stirred cell; 6 = membrane; 7 = stirrer bar). Bottom: Amicon stirred ceil sys-
`tem showing the reservoir, the three-way valve, and the 200-mL model 8200 stirred
`cell, which is on top of a magnetic stirrer (adapted from Amicon catalog, with
`permission).
`
`each. The hollow fiber modules, which are another embodiment of thin-channel
`devices, are $300 each and made of polyethersulfone. Good scaleup data can
`be obtained with these devices, since they simulate the cross-flow design of
`industrial modules.
`Figure 5.7 shows some more laboratory-scale modules. The pump capacities
`needed tend to be higher for these modules, especially the tubular modules.
`
`GE-1009.017
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`176
`
`EQUIPMENT
`
`Figure 5.5. Amicon thin-channel cell for laboratory applications. The cell assembly is
`shown on top of a peristaltic pump, which recycles the process fluid through shallow
`spiral channels in a plate placed just above the membrane surface to minimize
`concentration polarization effects (adapted from Amicon catalog, with permission).
`
`However, these modules can provide even more realistic data than the stirred
`cell devices, if operated in the appropriate manner.
`Figure 5.8 shows a comparison of the performance of dead-end unstirred
`cells, stirred cells, and thin-channel devices for the MF of turbid bovine serum.
`Thin-channel devices (labeled "TCF" in the graph) performed better than the
`other devices, especially when operated in the recirculation mode as shown
`
`GE-1009.018
`
`

`
`Figure 5.6. Cross-flow membrane equipment for bench-top laboratory applications
`(model CH2): left: spiral-wound cartridge (Amicon’s $I type) coupled to peristaltic
`pump and 2-L feed reservoir; right: Amicon’s H1 type hollow fiber cartridges in a
`similar CH2 system.
`
`Figure 5.7. Laboratory-scale cross-flow membrane modules. I = Koch tubular
`(HFM-180-TOS, 0.05 m2); 2 = Hoechst spiral (5SFXABU, 0.1 m2); 3 = Koch spiral
`(S2-HFK131-FY~, O. 18 m2); 4 = USFilter single tube ceramic (1TI-70-125-LI, 0.027
`m2); 5= CeraMem LMC with 4-ram channels (0.05 m2); 6 = A/G Technology
`TurboTube (CFP-5-K-4XT2C, 0.046 m2); 7 = A/G Technology hollow fiber module
`(UFP-5-C5, 0.28 m2).
`
`177
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`GE-1009.019
`
`

`
`178
`
`EQUIPMENT
`
`60[
`
`TCF1 O, 16-mil .. ~
`
`TCF10,16 mil
`
`Dead-end cell
`(unstirred)
`
`20~-
`0
`
`20
`
`100 120 140
`40
`80
`60
`Time (minutes)
`Figure 5.8. Comparison of the performance of laboratory devices for the ultrafil-
`tration of turbid bovine serum. Pressure was 25 psig (1.72 bar) (adapted from
`Porter 1979).
`
`in Figure 5.5. The TCF10 cell performed better when the channel height was
`reduced from 30 mils (0.76 mm) to 16 mils (0.4 mm). This is because the
`shear rate increased (with the same recirculation rate) when the channel height
`was reduced [see Equations (4.38) and (4.39)], leading to an increase in mass
`transfer coefficients and flux [Equations (4.35) and (4.36)].
`Flux data obtained in stirred cells are only a gross approximation of the
`flux that can be obtained with larger, industrial-type cross-flow modules. Po-
`larization control is usually better in the larger devices, especially with fouling
`feedstreams. However, stirred cells are useful in rapidly evaluating the rejection
`properties of membranes under limited conditions. At the very least it will help
`narrow the range of membranes that have to be evaluated on a pilot scale. These
`devices are not recommended for evaluating the engineering parameters of a
`membrane process.
`
`~.B.
`INDUSTRIAL EQUIPMENT
`
`5.B.1.
`TUBULAR MODULES
`
`Tubular modules (Figure 5.9) are among the earliest design of industrial-scale
`membrane equipment. Polymeric membranes are cast on the inside of porous
`
`GE-1009.020
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`

`
`Industrial Equipment
`
`179
`
`End Cap
`
`Housing Membrane Tubes End Cap
`
`.
`
`¯ ’"
`
`Membrane
`\
`
`Perforated Rigid ’..
`Outer Tube
`
`.
`
`FEED ~
`
`~RETENT~,TE
`
`Permeate
`Figure 5,9. Schematic of a tubular membrane designed for ultrafiltration applica-
`tions.
`
`paper or plastic inserts with internal diameters ranging from 0.5’~ (12.5 mm) to 1"
`(25 mm) and lengths varying from 2 to 20 ft (0.6-6.4 m). Most ceramic modules
`also fit the definition of tubular modules but tend to be smaller in diameter,
`ranging from 2-6 mm, with lengths of individual tubes or multichannel elements
`up to 1.1 m (Section 2.E.) Tube diameters are essentially a compromise between
`the optimum size for minimum energy consumption (which may be as low as
`1.0 mm diameter or less) and the cost of making membranes and support tubes
`in such small diameters.
`Several of these tubes may be assembled in a housing in a shell-and-tube
`arrangement. The end-caps will determine whether the feed flows through the
`tubes in series[typical of reverse osmosis (RO)] or in parallel (typical for UF
`and MF applications, as shown in Figure 5.9). The permeate collects in the
`shell side of the housing and is removed through side ports under the pres-
`sure gradient from the feed side. This pressure required to remove permeate
`from the module should be considered in the process design. A significant
`back-pressure can be created in the permeate line if the permeate piping is not
`sized properly or if there are too many fittings and elevations in the permeate
`line. Excessive back-pressure should be avoided in membrane modules, not
`only because it reduces flux [Equation (4.6)], but it could damage membranes
`that are not self-supporting. This includes polymeric tubular modules, spirals,
`and plates. On the other hand, most inorganic modules and hollow fibers can
`withstand high back-pressures, which is an advantage in MF applications (see
`Section 6.E.4.).
`Figures 5.10 and 5.11 show cross sections of typical tubular modules. Fig-
`ure 5.12 shows how a 1’r tubular system is assembled. Table 5.1 shows specifi-
`cations of Koch’s tubular membranes.
`
`GE-1009.021
`
`

`
`Figure 5.10. Tubular UF/MF module designs available from Koch: left to right: I"
`diameter tube, ULTRA-COR module with seven tubes of O.5" diameter, SUPER-COR
`module with 19 tubes of 0.5" diameter each.
`
`Figure 5.11. Tubular modules from AMT (MAG-19 and MAG-7).
`
`180
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`GE-1009.022
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`181
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`182
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`EQUIPMENT
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`Table 5.1. Specifications of Koch tubular UF and MF
`membranes and modules.
`
`Module
`
`Module
`Diameter Length
`(cm/inches) , (m/ft)
`
`Membrane
`Area per
`Module (mZ/ft2)
`
`Tubular (1r~ diameter single tube)
`Tubular (1r~ diameter single tube)
`ULTRA-COR (7 tubes, 0.5" dia. each)
`SUPER-COR (19 tubes, 0.5" dia. each)
`
`2.5/1.0
`2.5/1.0
`3.8/1.5
`7.6/3.0
`
`1.5/5
`3.0/10
`3.0/10
`3.0/10
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`0.10/1.1
`0.2/2.2
`0.68/7.4
`2.2/24.0
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`Membrane*
`
`NMWCO**
`
`Maximum
`Temperature
`(°C) at pH 6
`
`Operating
`pH at 25°C
`
`Maximum
`Pressure
`(bar/psi)
`
`H FM-100
`H FA-251 a
`HFM-180
`H FM-183c
`HFP-276b
`MS D-400a
`MS D-181
`M S D-405a
`MFK-617
`MMP-406a
`MMP-404a
`MFK-615
`MMP-516a
`MMP-407a
`MMP-600
`MMP-602
`
`10,000
`15,000
`18,000d
`50,000
`35,000
`100,000
`200,000
`250,000
`0.3/t
`0.2/z
`0.4/~
`1.2/t
`2/z
`2-3/~
`1-2/~
`2-3/~
`
`90
`50
`90
`90
`90
`90
`90
`90
`90
`90
`90
`90
`90
`90
`90
`90
`
`1-13
`2-8
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
`1-13
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`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`10.5/150
`3.5/50
`3.5/50
`3.5/50
`
`*All tubular membranes made of PVDF except MFK-615 and MFK-617, which are PES
`** Nominal molecular weight cut-off
`aHydrophilic membrane; bAnionic; CCationic; d 18,000-180,000, depending on application
`
`The PCI tubular system (Figure 5.13) uses a slightly different approach. The
`membrane is cast on the inside of a synthetic paper tube while this tube is being
`continuously manufactured in a helical-spiral design. Membrane formulations
`are slightly different than those used for manufacture of fiat sheets of the same
`membrane to allow for the stretching that takes place when the tubes are pres-
`surized during operation. These paper membrane inserts fit inside perforated
`stainless steel support tubes, which are about 14 mm in diameter. This results
`in an inner (flow channel) diameter of 12.5 mm. In the B1 module of PCI, 18 of
`these tubes are mounted together in a shell-and-tube arrangement in a housing
`using end-caps that can link the tubes, either in series or parallel (Figures 5.9
`and 5.13). The end-caps are retained by studs screwed into tube plates, which
`hold the tubes in place. A specially designed, crevice-free rubber seal is used
`
`GE-1009.024
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`

`
`Industrial Equipment
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`183
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`Figure 5.13. PCI tubular modules: left: The B1 module cross section showing tubu-
`lar membrane inserts in individual permeate stainless steel tubes; center left: B1
`module with end-cap: permeate off-take pipe and feed entry pipe are visible; center
`right: the A19 module showing the multitube core with retaining bolts; right: A19
`cross section; permeate port can be seen.
`
`to seal the ends of the membrane inserts and the end-caps. Series flow (i.e.,
`the feed enters one of the 18 tubes and flows in series through all 18 tubes) is
`used when low flow rates can be used, as in RO applications. Parallel flow is
`more common for UF applications. A combination of series and parallel flow
`("twin-entry") is also used, where the flow goes through two tubes in parallel
`at the same time and then in series through the remaining tubes, i.e., for a total
`of nine passes through a module.
`The A 19 design of PCI does not use individual stainless steel support tubes;
`instead, the 19 tubes are bunched together and cast in epoxy resin at each
`end. This bundle is then placed in a stainless steel housing (Figure 5.13). The
`permeate from the individual tubes collects in the shell and is removed through
`side connections to a central permeate header.
`Figure 5.14 shows the arrangement of modules of a typical multistage UF
`plant (modules are usually horizontal for tubular membranes because of their
`long lengths). Table 5.2 lists UF and MF tubular membranes available from
`PCI. Inorganic membranes, which are usually tubular in design, are shown in
`Figures 5.15 and 5.16. Specifications of some tubular modules are listed in
`Table 5.3.
`
`GE-1009.025
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`

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`184
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`GE-1009.026
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`

`
`Industrial Equipment
`
`185
`
`Table 5.2. Specifications of PCI tubular UF and MF
`membranes and modules.
`
`Membrane Area Maximum
`per Module
`Pressure
`(bar/psi)
`(mZ/ftz)
`
`0.9/10
`1.7/18
`2.6/28
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`1.0/11
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`2.1/22
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`16/230
`16/230
`16/230
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`7/100
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`7/100
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`7/100
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`Module
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`B1 (parallel flow
`and twin-entry)
`
`Module
`Diameter
`(cm/inches)
`
`10/3.9
`10/3.9
`10/3.9
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`A19 (parallel flow)
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`8.3/3.25
`
`Length
`(m/ft)
`
`1.2/4
`2.4/8
`3.6/12
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`1.52/5
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`8.3/3.25
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`3.05/10
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`8.3/3.25
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`3.66/12
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`2.5/26.5
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`Membrane (and
`Material)
`
`NMWCO
`
`Maximum
`Temperature
`(°C) at pH 6
`
`Operating pH
`at 25°C
`
`Maximum
`Pressure
`(bar/psi)
`
`CA202 (CA)*
`ES404 (PES)
`PU608 (PS)
`ES209 (PES)
`PU120 (PS)
`AN620 (PAN)*
`ES625 (PES)
`FPA10 (PVDF)
`FP100 (PVDF)
`FPA20 (PVDF)
`FP200 (PVDF)
`V4000 (PVC)
`L6000 (FP)
`
`2,000
`4,000
`8,000
`9,000
`20,000
`25,000
`25,000
`100,000
`100,000
`200,000
`200,000
`200,000
`200,000
`
`30
`80
`80
`80
`80
`60
`80
`60
`80
`60
`80
`50
`60
`
`2-7
`2-12
`2-12
`2-12
`2-12
`2-10
`2-12
`2-10
`2-12
`2-10
`2-12
`2-12
`2-12
`
`25/360
`30/450
`30/450
`30/450
`15/225
`10/150
`15/225
`7/100
`10/150
`7/100
`10/150
`10/150
`10/150
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`*= Hydrophilic membrane
`CA = cellulose acetate; PAN = polyacrylonitrile; PES = polyethersulfone; PS = polysulfone; PVC
`= polyvinyl chloride; PVDF = polyvinylidene flouride; FP = fluoropolymer
`
`5.B.l.a.
`CHARACTERISTICS OF TUBULAR MEMBRANES
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`I. Owing to the relatively large channel diameters, tubular units are capable
`of handling feed streams and slurries containing fairiy large particles. As
`a general rule of thumb, the largest particle in the feed should be less than
`one-tenth the channel height. Thus, feedstreams containing particles as large
`as 1250/zm can be processed in 0.5" tubular units, while the t.0~t units can
`handle particles as large as 2500 lzm (particle size is expressed in terms of
`its largest dimension).
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`GE-1009.027
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`GE-1009.028
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`187
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`GE-1009.029
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`

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`188
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`EQUIPMENT
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`Figure 5.16. Scepter stainless steel membrane module (courtesy of Graver Separa-
`tions).
`
`2. Tubular units with these diameters are operated under turbulent flow con-
`ditions with Reynolds numbers usually greater than 10,000. Recommended
`velocities for UF are 2-6 m/sec, depending on the module (ceramic mem-
`branes are operated at the higher velocities). This will result in flow rates
`of 15-60 L per minute per tube, depending on the tube diameter. For a
`PCI or Koch tubular module, this means a pump capacity of 16-34 m3/h
`[70-150 gallons per minute (gpm)] per module. For ceramic membranes,
`this may require 300 gpm for the CeraMem PMA industrial module and for
`the USFilter 19P19-40 module.
`3. For polymeric 0.5" tubes of 8-12 ft in length, pressure drop averages 2-3 psi
`per tube at these velocities. This is also the pressure drop for the module
`if all tubes are in parallel flow. If the individual tubes are connected in
`series, typical pressure drops for 0.5-1.0" polymeric tubes will be about
`30-40 psi (2-2.5 bar). For twin-entry modules from PCI, pressure drop
`may be 15-20 psi per module. For ceramic membranes, pressure drop may
`be 15-25 psi, depending on the channel diameter and fluid properties. In
`general, this combination of pressure drop and high flow rates makes tubular
`modules the highest in energy consumption among all the module types (see
`Section 7.E for calculations).
`4. The straightforward open tube design and the high Reynolds numbers makes
`it easy to clean by standard clean-in-place (CIP) techniques. It is also possible
`to inse