List of Figures ............................................... xix
List of Tables ................................................ xxi
Preface ..................................................... xxiii
Chapter 1 Introduction
1.0 OVERVIEW AND PURPOSE ....................................... 2
2.0 ORGANIZATION AND STRUCTURE OF THE MANUAL ................... 3
3.0 MEMBRANE BIOREACTOR PROCESS BACKGROUND ..................... 4
3.1 Membrane Bioreactor Process Introduction ................... 4
3.2 Significant Components of a Membrane Bioreactor
System ................................................ 6
3.2.2 Preliminary Treatment .......................... 6
3.2.2 Primary Treatment .............................. 7
3.2.3 Flow Equalization .............................. 7
3.2.4 Biological Reactors ............................ 8
3.2.5 Membrane Systems ............................... 8
3.2.6 Disinfection ................................... 8
3.2.7 Solids Handling and Disposal ................... 9
3.3 Scales of Membrane Bioreactor Application ............. 9
4.0 HISTORY OF MEMBRANE BIOREACTOR DEVELOPMENT ................ 10
5.0 OVERVIEW OF MEMBRANE BIOREACTOR CAPABILITIES .............. 12
5.1 Benefits of Membrane Bioreactor Technology ................ 12
5.1.1 Footprint .......................................... 12
5.2.1 Absolute Biomass Retention and Ease of Operation ... 13
5.2.2 Effluent Quality ................................... 13
5.2 Challenges of Membrane Bioreactor Technology .............. 13
5.2.1 Cost ............................................... 13
5.2.2 Capacity ........................................... 14
5.2.3 New Technology ..................................... 14
5.3 Typical Drivers for Membrane Bioreactor Installation ...... 14
6.0 REFERENCES ................................................ 15
Chapter 2 Membrane Fundamentals
1.0 INTRODUCTION .............................................. 18
1.1 Membrane Bioreactor Process Overview ...................... 18
1.2 Membrane Performance Metrics .............................. 20
2.0 MEMBRANE EQUIPMENT AND CONSTRUCTION MATERIALS ............. 21
2.1 Membrane Classifications .................................. 21
2.1.1 Microfiltration .................................... 24
2.2.1 Ultrafiltration .................................... 25
2.2 Membrane Materials ........................................ 25
2.2.2 Polymeric ........................................... 26
2.2.2 Composite ........................................... 27
3.0 MEMBRANE SYSTEM CONFIGURATIONS ............................ 27
3.1 Membrane and Membrane-Element Types ....................... 27
3.2.2 Hollow Fiber ....................................... 28
3.2.2 Flat Sheets and Plates ............................. 29
3.2.3 Tubes .............................................. 30
3.2.4 Membrane Component Operation (Membrane Process
Configurations) .................................... 31
3.2.4.2 Internal (Immersed) ....................... 32
3.1.4.2 External (Sidestream) ..................... 32
3.1.4.3 Constant Flux Versus Constant Pressure
Operation ................................. 32
4.0 MEMBRANE OPERATION AND MAINTENANCE FUNDAMENTALS ........... 33
4.1 Membrane Fouling .......................................... 33
4.2.2 Effect on Membrane Performance ..................... 33
4.2.2 Types of Membrane Fouling .......................... 33
4.2.3 Membrane Fouling Mechanisms ........................ 34
4.2.4 Critical Flux ...................................... 36
4.2.5 Sustainable Flux ................................... 36
4.2 Biological Factors ........................................ 37
4.3 Fouling Control ........................................... 38
4.3.2 Introduction ....................................... 38
4.3.2 Air Scour .......................................... 38
4.3.3 Relaxation ......................................... 38
4.3.4 Adsorbent and Coagulant Addition ................... 39
4.3.5 Backwash Cleaning .................................. 39
4.3.6 Chemical Cleaning .................................. 40
4.3.7 Mechanical Cleaning ................................ 40
4.4 Membrane Failure Mechanisms ................................ 41
4.4.2 Irreversible Fouling ............................... 41
4.4.2 Membrane Integrity ................................. 41
5.0 REFERENCES ................................................ 42
6.0 SUGGESTED READINGS ........................................ 43
Chapter 3 Biological Process Fundamentals
1.0 INTRODUCTION .............................................. 46
2.0 PROCESS FUNDAMENTALS ...................................... 46
2.1 Biochemical Operations in Membrane Bioreactor Systems ..... 47
2.2 Governing Rate Kinetics ................................... 50
2.3 Biomass Growth and Substrate Consumption in Bioreactors ... 53
3.0 PROCESS CONFIGURATIONS .................................... 57
3.1 Fully Aerobic Membrane Bioreactor Systems ................. 59
3.2 Combined Biochemical Oxygen Demand and Biological
Nitrogen Removal Systems .................................. 60
3.2.2 Two-Stage Processes ................................ 62
3.2.2 Four-Stage Processes ............................... 64
3.2.3 Step-Feed Membrane Bioreactor ...................... 66
3.3 Combined Biological Nutrient (Nitrogen and Phosphorus)
Removal Systems ........................................... 67
3.3.2 Three-Stage Processes .............................. 68
3.3.2 Five-Stage Processes ............................... 70
4.0 CHARACTERISTICS OF ACTIVATED SLUDGE IN MEMBRANE
BIOREACTOR SYSTEMS ........................................ 71
4.1 Membrane Fouling and High Mixed Liquor Suspended
Solids Concentration ................................. 72
4.2 Effects of Operating Solids Retention Time,
Extracellular Polymeric Substances, and Soluble
Microbial Products on Membrane Fouling .................... 73
4.3 Effects of Mixed Liquor Suspended Solids Concentration
and Viscosity on Oxygen Transfer .......................... 74
4.4 Sludge Thickening Characteristics of Membrane Bioreactor
Sludge .................................................... 75
4.5 Sludge Bulking and Foaming ................................ 75
4.6 Observed Sludge Yields in Conventional Activated Sludge
and Membrane Bioreactor Systems ........................... 76
4.6.2 Observed Sludge Yields under Similar Process
Configuration and Operating Conditions ............. 76
4.6.2 Observed Sludge Yields and Solids Production
under Dissimilar Process Configuration and/or
Operating Conditions ............................... 77
4.7 Removal of Trace Contaminants in Conventional Activated
Sludge and Membrane Bioreactor Systems .................... 77
5.0 REFERENCES ................................................ 78
6.0 SUGGESTED READINGS ........................................ 83
Chapter 4 Membrane Bioreactor Process Design
1.0 INTRODUCTION .............................................. 87
2.0 MEMBRANE BIOREACTOR PROCESS OVERVIEW ...................... 87
2.1 Pretreatment .............................................. 87
2.2 Biological Process ........................................ 87
2.3 Membrane Separation Process ............................... 87
2.4 Post-Treatment ............................................ 88
2.5 Residuals Treatment ....................................... 88
3.0 DEFINITION OF MEMBRANE BIOREACTOR DESIGN BASIS ............ 88
3.1 Design Basis of Biological Process ........................ 88
3.2 Design Basis of Membrane Separation Process ............... 88
3.3 Equipment Redundancy ...................................... 89
4.0 PRETREATMENT .............................................. 90
4.1 Grit and Grease Removal ................................... 90
4.2 Screening ................................................. 90
4.3 Primary Clarification ..................................... 92
4.4 Peak Flow Management ...................................... 94
4.4.2 Peak Flow Treatment with Membranes ................. 94
4.4.2 Equalization ....................................... 95
4.4.3 Hybrid Processes for Peak Flow Treatment ........... 96
4.5 Small Plant Considerations ................................ 96
4.6 Industrial Applications ................................... 96
5.0 BIOLOGICAL PROCESS ........................................ 96
5.1 Configuration of Biological Reactor ....................... 97
5.2 Solids and Hydraulic Retention Time ....................... 97
5.3 Mixed Liquor Suspended Solids Concentration ............... 98
5.4 Return Activated Sludge Recirculation ..................... 98
5.5 Activated Sludge Characteristics .......................... 99
5.6 Oxygen Transfer ........................................... 99
6.0 MEMBRANE SEPARATION PROCESS .............................. 100
6.1 Membrane System Configuration ............................ 100
6.2 Flux Selection ........................................... 101
6.3 Mixed Liquor Suspended Solids Concentration .............. 102
6.4 Return Activated Sludge Recirculation .................... 102
6.5 Permeation ............................................... 103
6.6 Fouling Control .......................................... 105
6.6.2 Liquid-Velocity-Induced Shear ...................... 105
6.6.2 Membrane Air Scouring ............................. 105
6.6.3 Production Cycling - Relaxation and Backwashing ... 106
6.6.4 Chemical Cleaning ................................. 106
6.6.4.2 Maintenance Cleaning ..................... 107
6.6.4.2 Recovery Cleaning ........................ 107
6.6.5 Mechanical Cleaning ............................... 108
6.7 Ancillary Equipment ...................................... 109
6.7.2 Air-Extraction System ............................. 109
6.7.2 Membrane-Integrity Monitoring ..................... 109
6.8 Instrumentation and Process Control ...................... 109
7.0 POST-TREATMENT ........................................... 110
8.0 RESIDUALS TREATMENT ...................................... 111
8.1 Screenings ............................................... 111
8.2 Waste Activated Sludge ................................... 111
8.3 Foam and Scum ............................................ 111
8.4 Spent Cleaning Solutions ................................. 112
9.0 ENERGY OPTIMIZATION ...................................... 113
9.1 Design Elements to Reduce Energy ......................... 113
9.2.2 Balance of Solids ................................. 113
9.2.2 Pump Configurations ............................... 114
9.2 Operational Elements to Reduce Energy .................... 114
9.2.2 Membrane Air Scour ................................ 114
9.2.2 Optimize Membranes in Service ..................... 114
9.2.3 Optimize Dissolved Oxygen within the Biological
Process ........................................... 115
9.3 Equipment Elements to Reduce Energy ...................... 116
10.0 PROCESS SIMULATION FOR MEMBRANE SYSTEMS .................. 116
11.0 REFERENCES ............................................... 117
12.0 SUGGESTED READINGS ....................................... 119
Chapter 5 Membrane Bioreactor Facility Design
1.0 GENERAL CONCEPTS FOR DESIGN OF MEMBRANE BIOREACTOR
FACILITIES ............................................... 123
1.1 Introduction ............................................. 123
1.2 Membrane Bioreactor System Unit Process Configuration
and Layout ............................................... 123
1.3 Peak How Management and Membrane Bioreactor Facility
Design ................................................... 126
2.3.2 Flow Equalization ................................. 126
2.3.2 Design Tradeoffs with Peak Flow Management
Solutions ......................................... 127
1.4 Facility Hydraulic Gradeline and Hydraulic Design
Issues ................................................... 128
1.5 Pretreatment ............................................. 129
2.5.2 Coarse Influent Screening ......................... 129
2.5.2 Grit Removal ...................................... 130
2.5.3 Fine Screening .................................... 131
2.5.4 Package Headworks System .......................... 133
2.5.5 Primary Clarification ............................. 133
1.6 Design Considerations for New Membrane Bioreactor
Facilities ............................................... 134
1.7 Design Considerations for Membrane Bioreactor
Retrofitting Using Existing Bioreactors and/or Tanks ..... 134
1.8 Design Considerations for Upgrading to the Next
Generation of Membranes .................................. 134
1.9 Other Design Considerations .............................. 135
2.0 MEMBRANE BIOREACTOR FACILITY DESIGN PRINCIPLES AND
CONCEPTS ................................................. 135
2.1 Membrane Bioreactor System Layout ........................ 135
2.2.2 Biological Tank Design Issues Specific to
Membrane Bioreactors .............................. 135
2.2.2 Membrane Tank Shape and Redundancy ................ 137
2.2.3 Pump and Return Activated Sludge Configuration .... 137
2.1.3.1 Gravity Flow to the Membrane Tank and
Return Activated Sludge Pumping .......... 138
2.2.3.2 Pumping to Membrane Tank and Return
Activated Sludge Gravity-Flow Return
Tank ..................................... 138
2.2 Membrane Bioreactor Aeration ............................. 139
2.3 Membrane Permeation ...................................... 140
2.3.1 Pumped Permeation ................................. 140
2.3.2 Gravity Permeation ................................ 141
2.3.3 Pump-Enhanced Gravity Permeation .................. 141
3.0 ANCILLARY FACILITIES AND EQUIPMENT DESIGN CONCEPTS ....... 141
3.1 Membrane-Related Ancillary Facilities .................... 141
3.1.2 Clean-in-Place System ............................. 141
3.2.2 Permeate and Backpulse Pumps ...................... 142
3.2.3 Service Air ....................................... 143
3.1.2 Air Scour Blowers ................................. 143
3.2 Bioreactor Aeration Blowers .............................. 144
3.3 Pumping Facilities (Return Activated Sludge, Mixed
Liquor Recycle, Waste Activated Sludge, Mixed Liquor
Transfer, and Scum) ...................................... 144
3.4 Anoxic and Anaerobic Basin Mixers ........................ 145
3.5 Cranes and Hoists ........................................ 145
3.6 Membrane Bioreactor Tank-Related Considerations .......... 145
3.6.2 Dip Tanks ......................................... 145
3.6.2 Tank Design and Dimensioning ...................... 146
3.6.3 Tank Grating and Covers ........................... 148
3.6.4 Tank Coatings ..................................... 149
3.7 Instrumentation and Control .............................. 150
4.0 SURVEY OF CURRENT MEMBRANE BIOREACTOR PRACTICES IN
SIGNIFICANT DESIGN FIRMS ................................. 151
4.1 Survey Size .............................................. 151
4.2 Reasons for Selecting a Membrane Bioreactor Process ...... 152
4.3 Project Delivery and Membrane Procurement ................ 152
4.4 General Configuration .................................... 152
4.5 Pretreatment ............................................. 152
4.6 Membrane Flux ............................................ 152
4.7 Mixed Liquor Suspended Solids and Solids Retention Time .. 153
4.8 Return Activated Sludge Pumping .......................... 153
4.9 Freeboard ................................................ 153
4.10 Redundancy ............................................... 153
4.11 Construction Materials ................................... 153
5.0 REFERENCES ............................................... 154
6.0 SUGGESTED READINGS ....................................... 154
Chapter 6 Membrane Bioreactor Membrane Equipment Procurement
1.0 OVERVIEW ................................................. 160
1.1 Introduction ............................................. 160
1.2 Membranes and Membrane Equipment Procurement Approaches .. 160
1.3 Membrane Equipment Supplier Scope of Services ............ 162
2.0 MEMBRANE BIOREACTOR MEMBRANE EQUIPMENT PROCUREMENT ....... 163
2.1 Introduction ............................................. 163
2.2 Elements Common to Membrane Bioreactor Membrane
Equipment Procurement Approaches ......................... 163
2.2.2 Upfront Preliminary Engineering ................... 163
2.2.2 Selection Process ................................. 164
2.2.3 Contract Development .............................. 164
2.2.4 Bid Evaluation, Award, and Negotiation ............ 164
2.2.5 Coordination during Final Design and
Construction ...................................... 164
2.3 Membrane Bioreactor Procurement Approaches ............... 165
3.0 OTHER TOPICS TO CONSIDER WHEN PROCURING MEMBRANE
BIOREACTOR MEMBRANE EQUIPMENT ............................ 169
3.1 Membrane Bioreactor Warranties ........................... 169
3.2 Membrane Bioreactor Acceptance Testing ................... 171
3.3 Bid Alternates ........................................... 173
4.0 REFERENCES ............................................... 173
Chapter 7 Membrane Bioreactor Operation
1.0 OPERATION AND ROUTINE MONITORING ......................... 176
1.1 Membrane Bioreactor Standard Procedure ................... 176
1.1.2 Initial Startup and Commissioning ................. 177
1.1.1.1 Clean Water Testing ...................... 177
1.1.1.2 System Seeding ........................... 178
1.1.2 Typical Operation ................................. 179
1.1.2.1 Permeation Mode .......................... 181
1.1.2.2 Relaxation Mode .......................... 181
1.1.2.3 Backwash Mode ............................ 181
1.1.3 Membrane Tanks in Standby Mode .................... 182
1.1.4 Shutdown of the Membrane Tanks .................... 182
1.1.5 Safety ............................................ 182
1.2 Membrane Bioreactor Process Effects ...................... 183
1.2.1 Upstream Effects on the Membrane Bioreactor ....... 183
1.2.1 Membrane Bioreactor Effects on Downstream
Processes ......................................... 184
2.0 MAINTENANCE .............................................. 186
2.1 Membrane Cleaning ........................................ 186
2.2.2 Maintenance Cleaning .............................. 189
2.2.2 Recovery Cleaning ................................. 192
2.2.3 Physical Cleaning ................................. 192
2.2.4 Membrane Air-Diffuser Cleaning .................... 193
2.2 Identifying and Replacing Damaged Membranes .............. 194
2.3 Instrument Calibration ................................... 195
2.4 Membrane Storage, Handling, and Replacement .............. 195
2.5 Ancillary Systems ........................................ 197
2.5.2 Membrane Basins .................................... 197
2.5.2 Rotating Equipment ................................ 197
2.5.3 Compressed Air System and Cyclic Valves ........... 197
2.6 Manufacturer Support ..................................... 198
3.0 OPTIMIZATION ............................................. 198
3.1 Process .................................................. 198
3.2 Chemical Usage ........................................... 199
3.3 Operational Strategies for Energy Management ............. 199
3.4 Innovative Approaches .................................... 200
4.0 TROUBLESHOOTING .......................................... 201
5.0 LESSONS LEARNED .......................................... 204
5.1 Pretreatment ............................................. 205
5.2 Membrane Tanks ........................................... 205
5.3 Training ................................................. 207
5.4 Membrane Bioreactor Strengths ............................ 207
5.5 Membrane Bioreactor Weaknesses ........................... 207
6.0 OPERATIONAL CONSIDERATIONS THAT DIFFER FROM
CONVENTIONAL ACTIVATED SLUDGE SYSTEMS .................... 208
3.0 REFERENCES ............................................... 209
8.0 SUGGESTED READINGS ....................................... 210
Appendix A Standard Membrane Bioreactor Computations
1.0 INTRODUCTION ............................................. 214
2.0 DESIGN EXAMPLE OVERVIEW .................................. 214
2.1 Design Flowrates and Maximum Monthly Loading Rates ....... 214
2.2 Design Temperature ....................................... 215
2.3 Treatment Objectives ..................................... 215
2.4 Overview of the Biological Reactor ....................... 215
2.5 Membrane Design and Redundancy Requirements .............. 216
3.0 STANDARD COMPUTATIONS .................................... 216
3.1 Membrane System Design Information ....................... 216
3.2 Parameter Definitions .................................... 216
3.3 Required Membrane Area ................................... 218
3.4 Required Number of Small Membrane Subunits with Ten
Percent Spare ............................................ 218
3.1 Required Number of Large Membrane Subunits ............... 218
3.6 Required Membrane Tank Volume ............................ 218
3.7 Instantaneous, Temperature-Corrected Flux ................ 219
3.8 Peak-Day Solids Loading Rate ............................. 219
3.9 Air Scour Air Demands .................................... 220
3.10 Membrane Permeability .................................... 220
4.0 RECOVERY CLEANING CALCULATIONS ........................... 220
4.1 Membrane Tank Drain Pump ................................. 221
4.2 Recovery Cleaning Chemical Volume ........................ 221
5.0 REFERENCE ................................................ 222
Appendix В Glossary-index ..................................... 229
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