Reverse Osmosis

Preface to the 3rd Edition xxi Acknowledgements xxiii Section I: Fundamentals 1 1 Introduction to Reverse Osmosis: History, Challenges, and Future Directions 3 1.1 Introduction 3 1.2 A Brief History of Reverse Osmosis 5 1.2.1 Early Development 5 1.2.2 Advances 1970s–1980s 10 1.2.3 Advances from 1990s through the Early 2000s 12 1.3 Challenges and Prospects 14 1.3.1 Membrane Materials Development 15 1.3.2 Modification of Element Construction for Ultra-High Pressure or High-Temperature Operation 17 1.3.2.1 Ultra-High Pressure Spiral Wound RO 17 1.3.2.2 High-Temperature Elements 18 1.3.3 Optimization of RO Element Feed Channel Spacer 19 1.3.4 Other Advances and Future Requirements 23 1.4 Summary 26 Symbols 26 Nomenclature 27 References 27 2 Principles and Terminology 33 2.1 Semipermeable Membranes 33 2.2 Osmosis 33 2.3 Reverse Osmosis 35 2.4 Basic Performance Parameters: Recovery, Rejection, and Flux 35 2.4.1 Recovery and Concentration Factor 35 2.4.2 Rejection 38 2.4.3 Flux 41 2.4.3.1 Water Flux 41 2.4.3.2 Solute Flux 43 2.5 Filtration 43 2.5.1 Dead-End Filtration 43 2.5.2 Cross-Flow Filtration 43 2.6 Concentration Polarization 45 Symbols 47 Nomenclature 48 References 48 3 Membranes: Transport Models, Characterization, and Elements 51 3.1 Membrane Transport Models 51 3.1.1 Solution-Diffusion Transport Model 52 3.1.2 Modified Solution-Diffusion Transport Models 55 3.1.2.1 Solution-Diffusion Imperfection Model 55 3.1.2.2 Extended Solution-Diffusion Model 56 3.1.3 Pore-Based Transport Models 56 3.1.4 Models Based on Non-Equilibrium Thermodynamics 57 3.2 Polymeric Membranes 57 3.2.1 Cellulose Acetate 57 3.2.2 Linear Polyamide (Aramids) 61 3.2.3 Fully Aromatic Polyamide Composite Membranes 63 3.2.3.1 NS-100 Membrane 64 3.2.3.2 FT-30 Composite Membrane 67 3.2.4 Characterization of CA and Composite Polyamide Membranes 73 3.2.4.1 Surface Roughness 73 3.2.4.2 Zeta Potential (Surface Charge) 76 3.2.4.3 Hydrophilicity 76 3.2.5 Other Membrane Polymers 78 3.3 Membrane Elements 80 3.3.1 Plate and Frame Elements 81 3.3.2 Tubular Elements 82 3.3.3 Hollow Fine Fiber Elements 83 3.3.4 Spiral Wound Elements 84 3.4 Specialty Membranes and Elements 91 3.4.1 Specialty Membranes 91 3.4.1.1 Dry Membranes 91 3.4.1.2 Boron-Rejecting Membranes 92 3.4.2 Specialty Elements 93 3.4.2.1 Sanitary Elements 93 3.4.2.2 Disc Tube Elements 94 3.4.2.3 Vibratory Shear Enhanced Processing (VSEP) Elements and System 94 3.4.2.4 Ultra-High Pressure and High Temperature Elements 95 Symbols 95 Nomenclature 96 References 97 Section II: System Design and Engineering 103 4 Basic Design Arrangements and Concentration Polarization Guidelines 105 4.1 Arrays and Stages 105 4.1.1 Recovery per System Array 106 4.1.2 Element-By-Element Flow and Quality Distribution 108 4.1.3 Flux Guidelines 109 4.1.4 Cross-Flow Velocity Guidelines for Array Design 111 4.1.5 Concentrate Recycle 112 4.2 Passes 113 Symbols 115 Nomenclature 115 References 115 5 RO System Design Using Design Software 117 5.1 RO System Design Guidelines 117 5.2 Step-by-Step Design—Sample Problem 118 5.2.1 Step 1—Water Flux 119 5.2.2 Step 2—Membrane Selection 119 5.2.3 Step 3—Number of Elements Required 119 5.2.4 Step 4—System Array 120 5.3 Design Software 121 5.3.1 Water Application Value Engine (WAVE)— DuPont Water Solutions 123 5.3.2 IMSDesign—Hydranautics 131 5.3.3 Q+ Projection Software LGChem 135 5.4 Optimum Design Result for the Sample Problem 140 Symbols 141 Nomenclature 141 References 142 6 Design Considerations 143 6.1 Feed Water Source and Quality 143 6.1.1 Feed Water Source 143 6.1.2 Feed Water Quality and Guidelines 145 6.1.3 pH 147 6.1.3.1 pH Profile Through an RO System— Alkalinity Relationships 148 6.1.3.2 pH and Membrane Scaling Potential 148 6.1.3.3 pH Effects on Solute Rejection and Water Permeability 149 6.2 System Operations 149 6.2.1 Pressure 149 6.2.2 Compaction 151 6.2.3 Temperature 155 6.2.4 Balancing Flows 156 6.2.5 Designing for Variable Flow Demand 157 6.3 Existing RO System Design Considerations 157 6.3.1 Changing Membranes 157 6.3.1.1 Changing Membrane Area 158 6.3.1.2 Changing Membrane Types 158 6.3.1.3 Mixing Membrane Types 158 6.3.2 Increasing Recovery 159 6.3.3 Changing Feed Water Sources 160 6.3.4 Reducing Permeate Flow 161 Symbols 161 Nomenclature 161 References 162 7 RO Equipment 163 7.1 Basic RO Skid Components 163 7.1.1 Cartridge Filters 164 7.1.2 High Pressure Feed Pump 172 7.1.3 Pressure Vessels 177 7.2 Skid Design Considerations 181 7.2.1 Piping Materials of Construction 181 7.2.2 Feed Distribution Headers 183 7.2.3 Stage-by-Stage Cleaning 184 7.2.4 Sampling and Profiling/Probing Connections 187 7.2.5 Instrumentation 188 7.2.6 Controls and Data Acquisition/Analysis 193 7.2.6.1 System Control 193 7.2.6.2 Data Acquisition and Analysis 194 7.2.7 Designs for Variable Permeate Flow Demand 195 7.3 Energy Recovery Devices (ERDs) 196 7.3.1 ERD Types 196 7.3.2 ERD Applications for RO 197 7.3.2.1 Single-Stage RO 197 7.3.2.2 Multi-Stage RO 197 7.4 Clean-In-Place (CIP) Equipment 200 7.5 Mobile RO Equipment 203 Symbols 205 Nomenclature 205 References 206 Section III: Membrane Deposition and Degradation: Causes, Effects, and Mitigation via Pretreatment and Operations 207 8 Membrane Scaling 211 8.1 What is Membrane Scale? 211 8.2 Effects of Scale on Membrane Performance 212 8.3 Hardness Scales 215 8.3.1 Types of Hardness Scale 215 8.3.1.1 Carbonate-Based Hardness Scales 215 8.3.1.2 Sulfate-Based Hardness Scales 216 8.3.1.3 Other Calcium Scales: Calcium Phosphate and Calcium Fluoride 218 8.3.2 Mitigation of Hardness Scales 219 8.3.2.1 Chemical Pretreatment—Acid and Antiscalant Dosing 220 8.3.2.2 Non-Chemical Pretreatment—Sodium Softening and Nanofiltration 221 8.3.2.3 Operational Techniques—Flushing, Reverse Flow, and Closed Circuit Desalination 225 8.4 Silica Scale 226 8.4.1 Forms and Reactions of Silica 227 8.4.2 Factors Affecting Silica Scale Formation 228 8.4.3 Mitigation of Silica Scale 232 8.5 Struvite 236 8.5.1 What is Struvite? 236 8.5.2 Mitigation of Struvite 238 8.6 Scaling Mitigation Guidelines—Summary 239 Symbols 240 Nomenclature 240 References 240 9 Generalized Membrane Fouling 249 9.1 What is Membrane Fouling? 249 9.2 Classification and Measurement of Potential Foulants 250 9.2.1 Settleable and Supra-Colloidal Particulates 251 9.2.2 Colloids 252 9.2.2.1 Measurement of Colloids for RO Applications—Silt Density Index (SDI15) 252 9.2.2.2 Measure of Colloids—Modified Fouling Indices 255 9.2.2.3 Summary of Colloidal Fouling Indices 257 9.2.3 Natural Organic Material (NOM) 257 9.2.4 Other Organics 259 9.2.5 Other Foulants: Cationic Coagulants and Surfactants, and Silicone-Based Antifoams 259 9.2.6 Metals: Aluminum, Iron, Manganese, and Sulfur 259 9.2.6.1 Aluminum 259 9.2.6.2 Iron and Manganese 261 9.2.6.3 Hydrogen Sulfide 262 9.3 Effects of Fouling on Membrane Performance 265 9.3.1 Effects of Inorganic Foulants 266 9.3.1.1 Fouling with Larger Settleable and Supra-Colloidal Solids 266 9.3.1.2 Cake Layer Surface Fouling with Colloids 266 9.3.1.3 Feed Channel Fouling 268 9.3.1.4 Summary of Fouling Effects of Inorganic Particulates and Colloids 271 9.3.2 Effects of NOM and Other Organics 273 9.3.2.1 Effects of NOM—Humic Acids 273 9.3.2.2 Effects of Hydrocarbons 276 9.3.2.3 Effects of Cationic Coagulants and Surfactants 278 9.3.2.4 Summary of the Effects of Organic Surfactant and Antifoam Fouling on Membrane Performance 279 9.4 Pretreatment to Minimize Membrane Fouling 279 9.4.1 Primary Pretreatment—Clarification for Colloids and Organics (NOM) Removal 280 9.4.1.1 Coagulation 280 9.4.1.2 Flocculation 283 9.4.2 Pressure Filtration: Particles, SDI15 , and Organics Removal 283 9.4.2.1 Multimedia Pressure Filters: Suspended Solids Removal 283 9.4.2.2 Catalytic Filters: Soluble Iron, Manganese, and Hydrogen Sulfide Removal 287 9.4.2.3 Carbon Filters: TOC Removal 292 9.4.2.4 Walnut Shell Filters: Hydrocarbon Oil Removal 296 9.4.2.5 Cartridge Filters: What is Their Purpose? 299 9.4.3 Membrane Filtration Turbidity, SDI 15 , and Metal Hydroxide Removal 300 9.4.3.1 Membrane Materials and Elements 301 9.4.3.2 Membrane Filtration Operations— Polymeric Membranes 306 9.4.3.3 Membrane Filtration as Pretreatment for RO 311 9.4.4 Nanofiltration (NF): Organics and Color Removal 321 9.5 Feed Water Quality Guidelines to Minimize Membrane Fouling 323 Symbols 324 Nomenclature 324 References 326 10 RO Membrane Biofouling 335 10.1 What is RO Membrane Biofouling? 335 10.2 Factors Affecting Membrane Biofouling 339 10.2.1 Polyamide RO Membrane Characteristics 339 10.2.1.1 Membrane Surface Roughness 339 10.2.1.2 Surface Charge and Zeta Potential 339 10.2.1.3 Membrane Hydrophilicity 339 10.2.2 Feed Water Matrix 340 10.2.2.1 Concentration of Microorganisms and Nutrients 340 10.2.2.2 Feed Water Ionic Strength and pH 341 10.2.2.3 Pretreatment Antiscalants 341 10.2.2.4 Feed Water Organic Concentration and Fouling 341 10.2.3 RO System Hydrodynamics 341 10.3 Effects of Biofouling on Membrane Performance 342 10.3.1 Scale Formation 342 10.3.2 Hydrodynamic Effects on Performance 342 10.4 Measurement of Biofouling 343 10.4.1 Predictive Techniques 343 10.4.1.1 Assimilable Organic Carbon (AOC) 343 10.4.1.2 Adenosine Triphosphate (ATP) and the Biofilm Formation Rate (BFR) 344 10.4.2 Plate Counts 344 10.4.2.1 Heterotrophic Plate Counts (HPC) 344 10.4.2.2 Total Direct Counts (TDC) 345 10.5 Mitigation Techniques 345 10.5.1 Pretreatment 346 10.5.1.1 Reduction of Feed Water Nutrients and Microorganisms 346 10.5.2 Disinfection 348 10.5.2.1 Physiochemical Disinfection Method— Ultraviolet (UV) Light 348 10.5.2.2 Chemical Disinfection—Oxidizing Biocides 353 10.5.2.3 Chemical Disinfection—Non-Oxidizing Biocide 368 10.5.2.4 Biocides Not Recommended for Use with Polyamide RO Membranes 370 10.5.2.5 Chemical Disinfection—Prospective Biocides for RO 370 10.5.3 Membrane Cleaning for Biofouling Removal 373 10.5.4 Membrane “Sterilization” 375 10.5.5 Biocide Flushing 375 10.6 Biofouling and Mitigation Summary 376 Symbols 378 Nomenclature 378 References 379 11 Membrane Degradation 387 11.1 Chemical Degradation 388 11.1.1 Polyamide Layer Degradation—Oxidation 388 11.1.1.1 Chlorine 388 11.1.1.2 Chloramine 396 11.1.1.3 Chlorine Dioxide 398 11.1.2 Polysulfone Support Layer Degradation 400 11.1.3 Polyester Fabric Degradation—Hydrolysis 402 11.1.4 Prevention of Chemical Damage 402 11.1.4.1 Removal of Oxidizers 402 11.1.4.2 Protection of Membrane Support Layers 404 11.2 Mechanical Damage 404 11.2.1 Physical Membrane Damage Due to Abrasion 404 11.2.2 Physical Membrane Damage Resulting from Operational Factors 407 Symbols 412 Nomenclature 412 References 412 Section IV: System Monitoring, Normalization, and Troubleshooting 417 12 Data Collection and Normalization 419 12.1 Data Collection 419 12.2 Data Normalization 422 Symbols 427 Subscripts 428 Nomenclature 428 References 428 13 Membrane Issues and Troubleshooting 431 13.1 Observed Performance Issues 432 13.1.1 High Permeate Solute Concentration 432 13.1.1.1 Increase in Feed Water Concentration of Ions 433 13.1.1.2 Hardness Scaling 433 13.1.1.3 Membrane Damage 434 13.1.1.4 Temperature Increase/Pressure Decrease 435 13.1.1.5 System Operations and Mechanical Issues 438 13.1.2 Changes in Permeate Flow 439 13.1.3 Changes in Feed Pressure 439 13.1.4 High Differential Pressure 440 13.2 Common Causes of Performance Failures 445 13.2.1 Mechanical Failures 445 13.2.2 RO Equipment Design 445 13.2.3 Operational Problems 446 13.2.4 Feed Water Quality Issues 446 13.2.5 Membrane Issues 446 13.3 Troubleshooting Techniques 447 13.3.1 Mechanical Inspection 447 13.3.2 Cartridge Filter Inspection 447 13.3.3 Water Analyses 448 13.3.4 RO Projections 449 13.3.5 Profiling and Probing 449 13.3.5.1 Profiling 449 13.3.5.2 Probing 452 13.3.6 Normalized Data Analysis 455 13.3.7 Autopsy 457 13.3.7.1 Visual Inspection—External 458 13.3.7.2 Visual Inspection—Internal 459 Symbols 471 Nomenclature 471 References 472 Section V: Off-Line Activities: Membrane Cleaning, Flushing, and Layup 475 14 Membrane Cleaning 477 14.1 When to Clean 478 14.2 Cleaning Chemicals 479 14.2.1 High pH Cleaning 480 14.2.2 Low pH Cleaning 481 14.3 Cleaning Equipment Design 483 14.3.1 Design of the RO Skid for Effective Cleaning 483 14.3.2 Design of the Cleaning Skid 484 14.3.2.1 Cleaning Tank 484 14.3.2.2 Cartridge Filters 486 14.3.2.3 Cleaning Pump 486 14.4 Cleaning Techniques 487 14.4.1 Conventional Cleaning 487 14.4.2 Two-Phase Cleaning 489 14.4.3 Reverse Cleaning 490 14.4.4 Preventative Cleaning 490 14.4.4.1 Extrapolative Preventative Cleaning 491 14.4.4.2 Direct-Osmosis High-Salinity (DO-HS) On-Line Cleaning Technique 491 14.5 Determining the Efficacy of Cleaning 493 14.6 Clean-In-Place (CIP) Versus Offsite Cleaning 494 14.6.1 CIP 494 14.6.2 Off-Site Cleaning 494 14.7 Membrane Disinfection 495 14.7.1 Hydrogen Peroxide/Peroxyacetic Acid 495 14.7.2 Non-Oxidizing Biocides 497 14.7.2.1 DBNPA 497 14.7.2.2 Isothiazolones—CMIT/MIT 499 14.7.2.3 Other Non-Oxidizing Biocides 500 Symbols 500 Nomenclature 500 References 501 15 Controlling Off-Line Membrane Deposition via Flushing and Layup 505 15.1 Membrane Flushing 505 15.1.1 End of Service Flush 506 15.1.2 Stand-By Flush 506 15.1.3 Return to Service Flush 507 15.2 Membrane Layup 508 15.2.1 Short-Term Layup 508 15.2.2 Long-Term Layup 508 15.2.2.1 Sodium Metabisulfite (SMBS) 508 15.2.2.2 DBNPA 510 15.2.2.3 CMIT/MIT 510 15.3 Membrane Preservation 510 Nomenclature 512 References 512 Section VI: Sustainability and Future Prospects 515 16 Concentrate Management 517 16.1 Discharge 517 16.1.1 Discharge to Surface Waters 517 16.1.2 Discharge to Sewer 518 16.1.3 Discharge to On-Site Treatment Facility 518 16.1.4 Deep Well Injection 518 16.2 Land Application 519 16.2.1 Irrigation 519 16.2.2 Evaporation Ponds 519 16.3 Reuse 519 16.3.1 Direct Reuse 520 16.3.1.1 Wash Down Systems 520 16.3.1.2 Cooling Tower Make-Up 520 16.3.2 Treated Concentrate for Reuse—Brine Minimization 520 16.3.2.1 Recovery RO Systems 520 16.3.2.2 Zero Liquid Discharge (ZLD) 522 16.4 Off-Site Disposal 523 16.5 Emerging Technologies for Concentrate Management 523 16.5.1 Membrane Distillation (MD) 524 16.5.2 Forward Osmosis (FO) 526 Symbols 529 Nomenclature 529 References 529 17 High-Recovery Reverse Osmosis 531 17.1 Single-Step High Recovery Processes 531 17.1.1 Closed Circuit RO (CCRO) 531 17.1.1.1 Managing Scale Formation 533 17.1.1.2 Managing Membrane Fouling 535 17.1.1.3 Energy Savings 536 17.1.2 Osmotically-Assisted RO (OARO) 538 17.1.3 Pulse Flow RO (PFRO ™) 542 17.1.4 Feed Flow Reversal (FFR) 545 17.2 Enhanced High Recovery Processes with Interstage Solute Precipitation 548 17.2.1 Intermediate Concentrate Demineralization (ICD) 549 17.2.2 Accelerated Seeded Precipitation (ASP) 551 17.3 Multi-Step High Recovery Membrane Processes 552 17.3.1 Toward Zero Liquid Discharge (ZLD) 552 17.3.2 Challenging Waters and Wastewaters 553 17.3.3 Commercialized Multi-Step, High-Recovery RO Processes 553 17.3.3.1 Optimized Pretreatment and Unique Separation (OPUS®) 554 17.3.3.2 High Efficiency Reverse Osmosis (HERO®) 556 Symbols 558 Nomenclature 558 References 559 18 New and Alternative Membrane Materials For Sustainability 565 18.1 Specific Requirements to Improve Sustainability 566 18.1.1 Membrane Performance 566 18.1.2 Fouling Resistance 568 18.1.3 Chlorine (Oxidant) Tolerance 570 18.1.4 Energy-Water Nexus 570 18.2 Membrane Materials to Meet RO Demineralization Challenges 571 18.2.1 Modification of Polyamide Interfacial Polymerization (IP) Preparation Chemistries and Techniques 572 18.2.2 Membrane Surface Modifications 575 18.2.3 Nanotechnology and Nanoparticle Membranes 578 18.2.3.1 Carbon Nanotube (CNT) Nanocomposite Membranes 578 18.2.3.2 Thin Film Nanoparticle (TFN) Membranes 584 18.2.4 Graphene Oxide (GO)-Based Membranes 586 18.2.5 Biomimetic Aquaporin Membranes 591 Symbols 594 Nomenclature 594 References 595 Index 601