Preface ................................................... xi
Acknowledgments ......................................... хiii
About the Authors ......................................... xv
Nomenclature ............................................ xvii
1 General Introduction ....................................... 1
1.1 Overview of Distillation Processes ......................... 1
1.2 Membrane Distillation (MD) ................................. 5
1.2.1 Historical Perspective .............................. 5
1.2.2 MD Process .......................................... 7
1.3 Osmotic Distillation (OD) ................................. 11
1.3.1 Historical Perspective ............................ 11
1.3.2 OD Process ......................................... 12
1.4 MD and OD as Alternatives to Established Stripping
Processes ................................................. 14
1.4.1 Nonvolatile Solutes Retention ...................... 15
1.4.2 Minimization of Heat Damage to Feed Components ..... 15
1.4.3 Organic Volatiles Retention ........................ 18
1.4.4 Production of Highly Concentrated Solutions ........ 19
1.4.5 Utilization of Waste Heat or Heat from Natural
Sources ............................................ 20
1.5 Established Stripping Processes ........................... 20
1.5.1 Multistage Flash Distillation (MSF) ................ 20
1.5.2 Multiple-Effect Distillation (MED) ................. 22
1.5.3 Vapor Compression Distillation (VCD) ............... 25
1.5.4 Freeze Concentration (EC) .......................... 26
1.5.5 Reverse Osmosis (RO) ............................... 28
1.5.6 Electrodialysis (ED) ............................... 31
1.6 Other Membrane Processes .................................. 32
1.6.1 Microfiltration (MF) ............................... 33
1.6.2 Ultrafiltration (UF) ............................... 34
1.6.3 Nanofiltration (NF) ................................ 36
1.7 Concluding Remarks ........................................ 38
2 Theoretical Aspects of Membrane Distillation .............. 39
2.1 Introduction .............................................. 39
2.2 MD Theory ................................................. 40
2.2.1 Preliminary Considerations ......................... 40
2.2.1.1 Concentration Polarization ..................... 42
2.2.1.2 Temperature Polarization ....................... 44
2.2.2 Overall Approach to Theoretical Treatment .......... 45
2.2.3 Overall Driving Force, Δρb ......................... 46
2.2.4 Overall Mass Transfer Coefficient, K ............... 50
2.2.4.1 Feed-Side Mass Transfer ........................ 51
2.2.4.2 Membrane Mass Transfer ......................... 54
2.2.4.3 Strip-Side Mass Transfer ....................... 60
2.2.5 Vapor Pressure Polarization Coefficient, θν ........ 60
2.2.5.1 DCMD ........................................... 61
2.2.5.2 AGMD ........................................... 64
2.2.5.3 SGMD ........................................... 66
2.2.5.4 VMD ............................................ 67
2.3 MD Membrane Requirements .................................. 68
2.4 Effect of Operating Conditions on MD Performance .......... 71
2.4.1 Feed Temperature ................................... 71
2.4.2 Strip Temperature .................................. 72
2.4.3 Feed Solutes Concentration ......................... 72
2.4.4 Feed Velocity ...................................... 73
2.4.5 Strip Velocity ..................................... 75
2.4.6 Membrane Type ...................................... 76
2.4.7 Summary of Conditions Affecting MD Performance ..... 77
2.5 MD Process Economics ...................................... 79
2.6 Concluding Remarks ........................................ 82
3 Theoretical Aspects of Osmotic Distillation ............... 85
3.1 Introduction .............................................. 85
3.2 OD Theory ................................................. 87
3.2.1 Preliminary Considerations ......................... 87
3.2.1.1 Concentration Polarization ..................... 87
3.2.1.2 Temperature Polarization ....................... 89
3.2.2 Overall Approach to Theoretical Treatment .......... 90
3.2.3 Overall Driving Force, Δρb ......................... 92
3.2.3.1 Selection of an Osmotic Agent .................. 93
3.2.3.2 Calculation of Δρb ............................. 95
3.2.4 Overall Mass Transfer Coefficient, K ............... 96
3.2.5 Vapor Pressure Polarization Coefficient, θν ........ 97
3.3 OD Membrane Requirements .................................. 97
3.4 Effect of Operating Conditions on OD Performance .......... 98
3.4.1 Osmotic Agent Concentration ........................ 99
3.4.2 Feed Solutes Concentration ......................... 99
3.4.3 Feed Velocity ..................................... 100
3.4.4 Strip Velocity .................................... 100
3.4.5 Feed and Strip Temperature ........................ 101
3.4.6 Membrane Type ..................................... 101
3.4.7 Summary of Conditions Affecting OD Performance .... 103
3.5 OD Process Economics ..................................... 103
3.6 Concluding Remarks ....................................... 105
4 Properties of Macroporous Hydrophobic Membranes .......... 107
4.1 Introduction ............................................. 107
4.2 Theoretical Aspects of Membrane Hydrophobicity ........... 108
4.3 Membrane Types ........................................... 111
4.3.1 Polypropylene (PP) ................................ 113
4.3.2 Polytetrafluoroethylene (PTFE) .................... 115
4.3.3 Polyvinylidene Fluoride (PVDF) .................... 118
4.3.4 Tailored PVDF-Based Membranes ..................... 118
4.3.5 Polyazole Membranes ............................... 119
4.3.6 Nanofibrous PVDF–PTFE Membranes ................... 121
4.3.7 Surface-Modified Hydrophilic Membranes ............ 122
4.3.8 Inorganic Membranes ............................... 122
4.4 Fouling of Hydrophobic Membranes ......................... 123
4.4.1 Inorganic Fouling or Scaling ...................... 126
4.4.2 Organic Fouling ................................... 127
4.4.3 Biological Fouling ................................ 129
4.4.4 Clean-in-Place (CIP) Operating Conditions ......... 129
4.5 Protection Against Membrane Wet-Out ...................... 130
4.6 Hydrophobicity Restoration ............................... 132
4.7 Membrane Module Requirements ............................. 132
4.7.1 Plate-and-Frame Modules ........................... 133
4.7.2 Spiral Wound Modules .............................. 134
4.7.3 Hollow-Fiber Modules .............................. 135
5 Membrane Distillation Applications ....................... 139
5.1 Introduction ............................................. 139
5.1.1 Water Recovery .................................... 140
5.1.2 Electrical Energy Consumption ..................... 141
5.1.3 Thermal Energy Consumption ........................ 141
5.2 Desalination ............................................. 142
5.2.1 Water Pretreatment ................................ 143
5.2.2 Brine Disposal .................................... 145
5.2.3 Applications ...................................... 145
5.3 Industrial Wastewater Treatment .......................... 147
5.3.1 Radioactive Waste Treatment ....................... 150
5.3.2 Concentration of Nonvolatile Acids ................ 153
5.3.3 Volatile Acid Recovery from Industrial Effluents .. 153
5.3.4 Salt Recovery by Membrane Distillation
Crystallization (MDC) ............................. 154
5.3.5 Textile Industry Applications ..................... 155
5.4 Production of Liquid Food Concentrates ................... 156
5.5 Miscellaneous Applications ............................... 161
5.5.1 Volatiles Recovery from Fruit Juice by VMD and
SGMD .............................................. 161
5.5.2 Dealcoholization of Fermented Beverages Using
DCMD .............................................. 162
5.5.3 Enhanced Ethanol Production Using DCMD ............ 163
5.5.4 Production of Pharmaceutical Products ............. 164
5.6 Concluding Remarks ....................................... 165
6 Osmotic Distillation Applications ........................ 167
6.1 Introduction ............................................. 167
6.2 Fruit and Vegetable Juice Applications ................... 176
6.2.1 Orange Juice ...................................... 176
6.2.1.1 Integrated MF-OD Processing ................... 176
6.2.1.2 Integrated UF-OD Processing ................... 179
6.2.1.3 Integrated UF-RO-OD Processing ................ 180
6.2.2 Apple Juice ....................................... 183
6.2.2.1 Preliminary Combined OD-MD Application ........ 183
6.2.2.2 Integrated UF-OD, UF-DCMD, and UF-Combined
OD-MD Processing .............................. 184
6.2.3 Kiwifruit Juice ................................... 187
6.2.3.1 Integrated UF-OD Processing ................... 187
6.2.3.2 Kiwifruit Aroma Recovery by PV ................ 188
6.2.4 Grape Juice ....................................... 190
6.2.4.1 Integrated UF-OD Processing ................... 190
6.2.5 Melon Juice ....................................... 193
6.2.5.1 Integrated MF-OD Processing ................... 193
6.2.6 Camu Camu Juice ................................... 196
6.2.6.1 Integrated MF-RO and MF-Combined OD-MD
Processing .................................... 196
6.2.7 Pomegranate Juice ................................. 198
6.2.7.1 Integrated UF-OD Processing ................... 198
6.2.8 Tomato Juice ...................................... 200
6.2.8.1 Integrated MF (or UF)-RO-OD Processing ........ 200
6.2.9 Passion Fruit Juice ............................... 203
6.2.9.1 Integrated MF-OD Processing ................... 203
6.2.9.2 Integrated UF-OD Processing ................... 204
6.2.10 Pineapple Juice ................................... 206
6.2.10.1 Integrated MF-OD Processing ................... 206
6.2.11 Cornelian Cherry, Blackthorn, and Common
Whitebeam Juice ................................... 207
6.2.11.1 Integrated UF-Combined OD-MD Processing ....... 207
6.2.12 Sour Cherry Juice ................................. 207
6.2.13 Cranberry Juice ................................... 208
6.2.13.1 Integrated MF-OD Processing ................... 208
6.3 Other Applications ....................................... 209
6.3.1 Recovery and Concentration of Polyphenols from
Olive Mill Wastewater ............................. 209
6.3.1.1 Integrated MF-NF-OD Processing ................ 209
6.3.1.2 OD and Combined OD-DCMD Processing without
Pretreatment .................................. 211
6.3.2 Recovery of Flavonoids from Orange Press Liquor ... 212
6.3.2.1 Integrated UF-NF-OD Processing ................. 212
6.3.3 Echinacea Extract Concentration ................... 213
6.3.3.1 Integrated PV-MF-Combined OD-MD Processing ..... 213
6.3.4 Reconcentration of Spent Osmotic Dehydration
Sucrose Solutions ................................. 215
6.3.5 Aroma Recovery from Artificial Solutions .......... 216
6.3.5.1 Integrated OD-VMD Processing ................... 216
6.4 Concluding Remarks ....................................... 218
7 Future Prospects for Membrane Distillation and Osmotic
Distillation ............................................. 221
7.1 Introduction ............................................. 221
7.2 Membrane Module Design ................................... 222
7.3 Membrane Protection Against Wet-Out ...................... 224
7.3.1 Reclamation of Water for Reuse During Long-
Duration Human Space Missions ..................... 225
7.3.2 Production of Citrus Fruit Juice Concentrates ..... 226
7.3.3 Whole Milk Concentration on the Farm .............. 227
7.3.4 Concentration of Detergent-Containing
Radioactive Waste Solutions ....................... 228
7.4 Utilization of Renewable Energy Sources .................. 228
7.5 Membrane-Based Factory Processes of the Future:
A Hypothetical Example ................................... 231
7.6 End Note ................................................. 235
References ............................................... 237
Index .................................................... 261
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