Preface xi
1 Overviews 1
1.1 Introduction 1
1.2 Generation Techniques of Microbubbles 3
1.2.1 Types of Microbubble Generators 3
1.2.1.1 Gasâ"Water Circulation-Type Microbubble Generators 3
1.2.1.2 Pressurizationâ"Decompression Type of Microbubble Generators 6
1.2.1.3 No Liquid Flow-Type Microbubble Generators 6
1.2.2 Scale of Microbubble Generators 8
1.3 Physical Properties of Microbubbles 10
1.3.1 Physics of Microbubbles 10
1.3.2 Microbubble Size and Measurement Techniques 12
1.3.2.1 Photographic Method 13
1.3.2.2 Dynamic Light Scattering (DLS) 16
1.3.2.3 Laser Diffraction 18
1.3.2.4 Particle Image Velocimetry (PIV) 19
1.3.2.5 Other Methods of Microbubble Size Measurement 20
1.4 Characterization of Microbubbles 21
1.4.1 Size Distribution 21
1.4.2 Hydrodynamic Properties 22
1.4.3 Electrical Properties 25
1.4.3.1 Effect of Gas Type 25
1.4.3.2 Effect of Addition of Surfactants 27
1.4.3.3 Effect of pH of Water 27
1.4.4 Coalescence and Density Control 28
1.4.5 Rheological Properties 30
Nomenclature 31
Greek Nomenclature 32
References 33
2 Mass Transfer of Microbubbles 43
2.1 Introduction 43
2.2 Fundamental Mass Transfer Theories Applicable to Microbubbles 44
2.2.1 Mass Transfer Models 44
2.2.2 Methods of Evaluation of Mass Transfer Coefficient 46
2.2.2.1 From Correlations 46
2.2.2.2 From Comparison of the Saturation of Gases 47
2.2.2.3 Using the Plug Flow Model 48
2.2.2.4 Using Higbieâs, and Fr¶sslingâs Theories 51
2.3 Dissolution Behavior of Microbubbles 52
2.4 Effect of Parameters on k l 54
2.4.1 Saturation Ratio 54
2.4.2 Presence of Surfactants 56
2.4.3 Presence of Salts 57
2.5 Dimensional Analysis of k L a 58
2.6 Mass Transfer in Reactive System 60
Nomenaclature 63
Green Nomenclature 66
Dimensionless Numbers 67
References 67
3 Hydrodynamics of Microbubbles 71
3.1 Introduction 71
3.2 Hydrodynamic Parameters 71
3.2.1 Bubble Rising Velocity 71
3.2.2 Bubble Drag Coefficient 73
3.2.3 Gas Holdup 75
3.2.3.1 Differential Pressure Transmitter 76
3.2.3.2 Fiber Optical Probe Method 76
3.2.3.3 Electrical Resistance Tomography (ERT) Method 77
3.2.4 Superficial Gas Velocity 79
3.3 Correlations of Void Fraction 79
3.4 Analysis of Flow Regimes 80
3.4.1 Swarm Velocity Method 81
3.4.2 Drift Flux Method 82
3.5 Factors Affecting the Bubble Size and Rise Velocity 82
3.5.1 Wall Effect 82
3.5.2 Effect of Surfactants 83
3.5.3 Effect of Water Viscosity 83
3.6 Hydrodynamics of Microbubbles Depending on Microbubble Generators 84
3.6.1 Hydrodynamics of MBs in Foam Gun (Drift Flux Model) 84
3.6.2 Hydrodynamics of Microbubbles in Sintered Plate Microbubble Generators 87
3.7 Hydrodynamics of Microbubbles Flow in Pipes 88
3.8 The Residence Time of Microbubbles in the Column 90
Nomenclature 90
Greek Nomenclature 92
References 93
4 Radical Generation by Microbubbles 95
4.1 Introduction 95
4.2 Radical Generation in O 2 ,N 2 , and Air Microbubbles 96
4.3 Radical Generation in O 3 Microbubbles 97
4.4 Application of Catalysts for Radical Generation 98
4.4.1 Homogeneous Catalytic Process 100
4.4.2 Heterogeneous Catalytic Process 103
4.5 Influence of Parameters on Catalytic Processes 107
4.6 Quantification of Radicals 108
4.6.1 Electron Spin Resonance Method 108
4.6.2 R ct Method 110
4.6.2.1 Determination of OH Radical Concentration 110
4.6.2.2 Evaluate the Contribution of OH Radical for Pollutant Degradation 114
Nomenclature 114
References 115
5 Water Treatment and Related Applications of Microbubbles 119
Dr Manish Kumar Sinha
5.1 Introduction 119
5.2 Preliminary and Primary Stages of Water Treatment 121
5.2.1 Aeration Process 121
5.2.2 Aerobic/Anaerobic Digestion Process 124
5.3 Secondary Effluent Treatment 124
5.3.1 Mining Wastewater 125
5.3.2 Pharmaceutical and Personal Care Products (PPCPs) Effluents 127
5.3.3 Sludge Removal Step 128
5.4 Tertiary Treatment 130
5.4.1 Disinfection 130
5.4.2 Dyes Wastewater Treatment 132
5.5 Ozonation and Biological Process 132
5.6 Fiber, Pharmaceuticals, and Other Wastewaters 135
5.7 Integration of Microbubble with Membrane Process for Water Treatment 136
References 137
6 Other Industrial Applications of Microbubbles 141
6.1 Introduction 141
6.2 Flotation and Mineral Beneficiation 141
6.2.1 Theory of Flotation 143
6.2.2 Kinetics of Microbubble (MB)-Induced Flotation 144
6.3 Cleaning and Degreasing 147
6.4 Scrubber 150
6.5 Biodiesel Production 151
6.6 Biogas Upgradation 154
6.7 Enhanced Oil Recovery by CO 2 -Microbubbles (MBs) 155
6.8 Microbubbles (MBs)-Membrane Systems 156
6.8.1 Membrane for Microbubble Generation 156
6.8.2 Modeling of Microbubble Size Generated from Porous Membrane 159
6.8.3 Membrane Cleaning 161
6.8.4 Simultaneous Use of Microbubbles and Membranes for Water Treatment 162
Nomenclature 164
Greek Nomenclature 166
References 166
7 CFD and Microbubbles 171
Dr Abhishek Yadav
7.1 Introduction 171
7.2 CFD Simulation 171
7.2.1 Two-Phase Flow Models 173
7.2.1.1 Two-Fluid Model 173
7.2.1.2 Interface Terms 180
7.2.2 Population Balance Model 180
7.2.2.1 Modeling of the Generation Term,S n 183
7.2.2.2 Implementation of Population Balance Model 185
7.2.2.3 Example of Coupling between Flow Equations and Population Balance Equations 185
7.2.3 Turbulence Model 187
7.2.3.1 The k â' ε Model 192
7.2.3.2 The k â' Ï Model 194
7.2.3.3 The k â' Ï SST Model 195
Nomenclature 196
Greek Nomenclature 198
References 198
8 Cost Estimation and Energy Consumption 203
8.1 Introduction 203
8.2 Identification of Operating Parameters 203
8.3 Cost Estimation 205
8.4 Power Measurement 206
8.5 Experimental Method of Evaluation of the Performance of Microbubble Generators 208
8.6 Estimation of Energy Consumption for Lab-Scale Microbubble-Based System 209
8.7 Case Studies on Application of Microbubbles in Industrial Processes 210
8.7.1 A Case Study on the Treatment of Highly Saline Wastewater Using Ozone Micro-Nano Bubbles (O 3 -MNBs) 210
8.7.1.1 Background and Objectives 210
8.7.1.2 Methodology 211
8.7.1.3 Results 211
8.7.1.4 Conclusions 212
8.7.2 A Case Study on MB-Mediated Simultaneous Removal of NO and SO 2 212
8.7.2.1 Background and Objectives 212
8.7.2.2 Methodology 213
8.7.2.3 Results 213
8.7.2.4 Conclusions 213
8.7.3 A Case Study on Enhancing Biodiesel Production Through MB-Mediated Ozonation Process 214
8.7.3.1 Background and Objectives 214
8.7.3.2 Methodology 214
8.7.3.3 Results 214
8.7.3.4 Conclusion 215
8.7.4 A Case Study on Innovative Methods for Fine Particle Recovery Using MBs 215
8.7.4.1 Background and Objectives 215
8.7.4.2 Methodology 215
8.7.4.3 Results 215
8.7.4.4 Conclusion 216
8.7.5 A Case Study on MB-Mediated Membrane De-fouling in Wastewater Treatment 216
8.7.5.1 Background and Objectives 216
8.7.5.2 Methodology 216
8.7.5.3 Results 217
8.7.5.4 Conclusion 217
8.7.6 A Case Study on the Separation of Low-concentration Molybdenum From Tungstate Solution 217
8.7.6.1 Background and Objectives 217
8.7.6.2 Methodology 218
8.7.6.3 Results 218
8.7.6.4 Conclusion 219
8.8 Scale-up Models 219
8.9 Case studies on Scale-up projects of MB flotation from lab to industrial scale 222
8.9.1 Enhancing Coal Flotation Efficiency with Cyclonic MBs Flotation Column 222
8.9.1.1 Background and Objectives 222
8.9.1.2 Methodology 222
8.9.1.3 Results 222
8.9.1.4 Economic Report 223
8.9.1.5 Costâ"Benefit Analysis 223
8.9.1.6 Financial Impact 223
8.9.1.7 Conclusions 224
8.9.2 Scale-up of MB-Based Pharmaceutical Wastewater Plant 224
8.9.2.1 Background and Objectives 224
8.9.2.2 Methodology 224
8.9.2.3 Challenges and Future Considerations 225
8.9.2.4 Conclusions 225
Nomenclature 225
Greek Nomenclature 226
References 227
Index 229
