Contents
Preface xv
Acknowledgements for the First Edition xvii
Acknowledgements for the Second Edition xix
Part 1: Fundamentals
1 Introduction and History of Development 3
1.1 Introduction 3
1.1.1 Uses of Reverse Osmosis 4
1.1.2 History of Reverse Osmosis Development 5
1.1.3 Recent Advances in RO Membrane Technology 10
1.1.4 Future Advancements 12
1.1.5 Advances Since First Edition of this Book 12
References 16
2 Reverse Osmosis Principles 19
2.1 Osmosis 19
2.2 Reverse Osmosis 21
2.3 Dead-End Filtration 22
2.4 Cross-Flow Filtration 23
3 Basic Terms and Defi nitions 25
3.1 Reverse Osmosis System Flow Rating 25
3.2 Recovery 26
3.3 Rejection 28
3.4 Flux 31
3.5 Concentration Polarization 33
3.6 Beta 34
3.7 Fouling 35
3.8 Scaling 38
3.9 Silt Density Index 40
3.10 Modifi ed Fouling Index 43
3.11 Langelier Saturation Index 46
References 47
4 Membranes 49
4.1 Transport Models 50
4.1.1 Solution–Diff usion Model (non-porous model) 50
4.1.2 Solution–Diff usion Imperfection Model
(porous model) 52
4.1.3 Finely-Porous Model (porous model) 53
4.1.4 Preferential Sorption – Capillary Flow Model
(porous model) 54
4.1.5 Phenomenological Transport Relationship
(Irreversible thermodynamics) 54
4.2 Membrane Materials 54
4.2.1 Cellulose Acetate Membranes—Asymmetric
Membranes 55
4.2.2 Polyamide and Composite Membranes 59
4.2.3 Improvements to Polyamide, Composite
Membranes 64
4.2.4 Other Membrane Materials 65
4.3 Membrane Modules 65
4.3.1 Plate and Frame Modules 66
4.3.2 Tubular Modules 67
4.3.3 Spiral Wound Modules 68
4.3.4 Hollow Fine Fiber Membrane Modules 80
4.3.5 Other Module Confi gurations 82
4.4 Commercially-Available Membranes 83
4.4.1 Seawater Water Membranes 83
4.4.2 Brackish Water Membranes 85
References 91
5 Basic Flow Patterns 95
5.1 Arrays 95
5.2 Recycle 100
5.3 Double Pass 101
5.4 Multiple Trains 103
6 Reverse Osmosis Skids 105
6.1 Cartridge Filters 106
6.2 Reverse Osmosis Feed Pumps 109
6.3 Pressure Vessels 116
6.4 Manifolding—Materials of Construction 123
6.5 Instrumentation 124
6.6 Controls 125
6.7 Data Acquisition and Management 127
6.8 Reverse Osmosis Skid 129
6.9 Auxiliary Equipment 129
6.10 Other Design Considerations 130
6.10.1 Access to Profile and Probe RO Membranes 130
6.10.2 Interstage Performance Monitoring
Instrumentation 130
6.10.3 Stage-by-Stage Membrane Cleaning 131
References 131
Part 2: Pretreatment
7 Water Quality Guidelines 135
7.1 Suspended Solids 135
7.2 Microbes 137
7.3 Organics 139
7.4 Color 139
7.5 Metals 140
7.6 Hydrogen Sulfide 141
7.7 Silica 145
7.8 Calcium Carbonate 150
7.9 Trace Metals—Barium and Strontium 151
7.10 Chlorine 152
7.11 Calcium 153
7.12 Exposure to Other Chemicals 155
References 155
8 Techniques and Technologies 157
8.1 Mechanical Pretreatment 159
8.1.1 Clarifiers 159
8.1.2 Multimedia Pressure Filters 167
8.1.3 High-Efficiency Filters 170
8.1.4 Carbon Filters 174
8.1.5 Iron Filters 176
8.1.6 Sodium Soft eners 182
8.1.7 Spent Resin Filters 185
8.1.8 Ultraviolet Irradiation 185
8.1.9 Membrane 187
8.2 Chemical Pretreatment 187
8.2.1 Chemical Oxidizers for Disinfection of Reverse
Osmosis Systems 188
8.2.2 Non-Oxidizing Biocides 195
8.2.3 Sodium Metabisulfite for Dechlorination 196
8.2.4 Antiscalants 197
8.3 Combination Mechanical Plus Chemical
Pretreatment—Lime Soft ening 201
8.3.1 Cold Lime Soft ening 202
8.3.2 Warm Lime Soft ening 202
8.3.3 Hot Process Soft ening 202
8.4 Sequencing of Pretreatment Technologies 204
8.5 Membrane Biofouling and Alternative Disinfectants 206
8.5.1 Membrane Biofouling 207
8.5.2 Techniques to Address Biofouling 208
8.5.3 Summary 230
References 230
Part 3: System Design
9 Design Considerations 237
9.1 Feed Water Quality 238
9.1.1 Feed Water Source 238
9.1.2 Total Dissolved Solids 240
9.1.3 Calcium and Natural Organic Matter 241
9.1.4 Chemical Damage 242
9.2 Temperature 242
9.3 Pressure 244
9.4 Feed Water Flow 245
9.5 Concentrate Flow 246
9.6 Beta 246
9.7 Recovery 249
9.8 pH 251
9.9 Flux 253
10 RO Design and Design Soft ware 255
10.1 Dow WAVE – Water Application Value Engine 258
10.1.1 Feed Water Specifi cation 263
10.1.2 RO System Confi guration 265
10.1.3 Chemical Adjustment 268
10.1.4 Special Features 268
10.1.5 Report Generation & Review 270
10.1.6 Batch Operation and Case Management 274
10.1.7 Comparison between WAVE and ROSA 275
10.2 Toray DS2 275
10.3 Hydranautics IMS Design 281
References 282
Part 4: Operations
11 On-Line Operations 285
11.1 Reverse Osmosis Performance Monitoring 285
11.2 Data Collection 286
11.3 Data Analysis and Normalization 287
11.3.1 Data Normalization 288
11.3.2 Normalization Soft ware 297
11.4 Preventive Maintenance 301
References 303
12 Performance Degradation 305
12.1 Normalized Permeate Flow 305
12.1.1 Loss of Normalized Permeate Flow 305
12.1.2 Increase in Normalized Permeate Flow 307
12.2 Normalized Salt Rejection 308
12.2.1 Loss of Salt Rejection 308
12.2.2 Increase in Salt Rejection 309
12.3 Pressure Drop 310
12.3.1 Loss in Pressure Drop 310
12.3.2 Increase in Pressure Drop 310
References 311
13 Off -Line Operations 313
13.1 System Flush 313
13.1.1 Off -Line Flush 314
13.1.2 Return to Service Flush 315
13.1.3 Stand-by Flush 315
13.2 Membrane Cleaning 316
13.2.1 When to Clean 316
13.2.2 How to Clean 317
13.2.3 Cleaning Chemicals 319
13.2.4 Cleaning Equipment 324
13.3 Membrane Lay-Up 326
13.3.1 Short-Term Lay-Up 327
13.3.2 Long-Term Lay-up 327
References 328
Part 5: Troubleshooting
14 Troubleshooting 331
14.1 Mechanical Evaluation 333
14.2 General Performance Issues 334
14.3 System Design and Performance Projections 334
14.3.1 System Design 334
14.3.2 Performance Projections 335
14.4 Data Assessment 336
14.5 Water Sampling 339
14.6 Membrane Integrity Testing 339
14.7 Profiling and Probing 340
14.8 Membrane Autopsy 342
14.8.1 Visual Inspection 343
14.8.2 Pressure Dye Test—Rhodamine B 349
14.8.3 Methylene Blue Test 349
14.8.4 Fujiwara Test 350
14.8.5 Spectroscopy 351
14.8.6 Other Tests 351
References 352
Part 6: System Engineering
15 Issues Concerning System Engineering 355
15.1 Sodium Water Soft ening 355
15.1.1 Sequencing of the Sodium Soft eners and RO 356
15.1.2 Sodium Soft ening and Antiscalants 357
15.2 Reverse Osmosis Sizing and Capacity 364
15.3 Membrane Cleaning: On-Site versus Off -Site 365
15.3.1 Off -Site Membrane Cleaning 365
15.3.2 On-Site Membrane Cleaning 366
15.4 Reverse Osmosis Reject Disposal Options 367
15.4.1 Discharge to Drain or Sewer 367
15.4.2 Discharge to Cooling Tower 368
15.4.3 Zero Liquid Discharge 369
References 371
16 Impact of Other Membrane Technologies 373
16.1 Microfiltration and Ultrafiltration 373
16.1.1 Microfiltration 386
16.1.2 Ultrafiltration 387
16.2 Nanofiltration 388
16.3 Forward Osmosis 392
16.4 Continuous Electrodeionization 398
16.5 HERO™ Process 408
References 413
Part 7: Frequently Asked Questions
17 Frequently Asked Questions 419
17.1 General 419
17.1.1 What Is Reverse Osmosis Used For? 419
17.1.2 What is the Diff erence Between Nanofiltration
and Reverse Osmosis? 420
17.1.3 What is the Diff erence Between Forward
Osmosis (FO) and Reverse Osmosis (RO)? 420
17.1.4 What is Data Normalization? 420
17.1.5 How do SDI and Turbidity Correlate? 421
17.1.6 Why Does the pH Drop from the RO Feed to
the RO Permeate? 421
17.2 Operational 421
17.2.1 When is it Time to Clean an RO Membrane? 421
17.2.2 How Long does it Take to Clean an RO System? 422
17.2.3 What Temperature Cleaning Solution Should
be Used to Clean Membranes? 422
17.2.4 Can Extended Soak Time Compensate
for Cleaning at Lower Temperature, for
Example, When the Heater is Not Working? 422
17.2.5 Should the Low or High pH Cleaning Be
Conducted First? 423
17.2.6 What Should Be Done if Cleaning Does
Not Return Performance to Baseline? 423
17.2.7 If the Clean-in-Place Pump cannot Provide the
Required Flow Rate, Can the Pump be Run at
Higher Pressure to Compensate? 423
17.2.8 What Should Be Done With Permeate
Th at is Generated During Membrane Cleaning? 423
17.2.9 Why is the Permeate Conductivity High aft er
Cleaning the Membranes? 424
17.2.10 Why is Chlorine Both Added and then
Removed Prior to the RO? 424
17.2.11 What Chemicals Can be Used to Disinfect
RO Membranes Directly? 424
17.2.12 Why does the RO Trip Off on Low
Suction Pressure? 425
17.2.13 Should RO Feed Water be Heated? 426
17.2.14 What Limits Recovery by an RO? 426
17.2.15 How do I Start Up an RO? 427
17.2.16 Do RO Membranes Need to be Preserved
When Taken Off Line? 427
17.2.17 Is there a Shelf Life for Reverse Osmosis
Membranes? 429
17.2.18 What is the Diff erence Between Membranes
that Have Been Wet Tested and those that
are Dry? 430
17.2.19 What is the Impact on the RO If the
Pretreatment System Fails, for Example,
If the Soft ener Leaks Hardness? 430
17.2.20 Can Diff erent Types of Membranes Be Used
in a single RO Unit? 431
17.2.21 What Species Should Be Included in an
RO Feed Water Analysis? 432
17.3 Equipment 433
17.3.1 What is the Footprint For an RO System? 433
17.3.2 What is a Variable Frequency Drive Used For? 433
17.3.3 What is the Diff erence Between Pleated,
String-Wound, and Melt-Blown Cartridge Filters? 434
17.3.4 What is the Correct Way to Install Shims and
the Th rust Ring? 434
17.3.5 How Should the Cleaning Pump be Sized? 435
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