PREFACE ........................................................ xi
l. INTRODUCTION ................................................ 1
1.1. Energy needs .......................................... 1
1.2. Energy and the challenge of global climate change ..... 2
1.3. Bioelectricity generation using a microbial fuel
cell — the process of electrogenesis .................. 4
1.4. MFCs and energy sustainability of the water
infrastructure ........................................ 6
1.5. MFC technologies for wastewater treatment ............. 7
1.6. Renewable energy generation using MFCs ................ 9
1.7. Other applications of MFC technologies ............... 11
2. EXOELECTROGENS ............................................. 12
2.1. Introduction ......................................... 12
2.2. Mechanisms of electron transfer ...................... 13
2.3. MFC studies using known exoelectrogenic strains ...... 18
2.4. Community analysis ................................... 22
2.5. MFCs as tools for studying exoelectrogens ............ 27
3. VOLTAGE GENERATION ......................................... 29
3.1. Voltage and current .................................. 29
3.2. Maximum voltages based on thermodynamic
relationships ........................................ 30
3.3. Anode potentials and enzyme potentials ............... 36
3.4. Role of communities versus enzymes in setting
anode potentials ..................................... 40
3.5. Voltage generation by fermentative bacteria? ......... 41
4. POWER GENERATION ........................................... 44
4.1. Calculating power .................................... 44
4.2. Coulombic and energy efficiency ...................... 48
4.3. Polarization and power density curves ................ 50
4.4. Measuring internal resistance ........................ 54
4.5. Chemical and electrochemical analysis of reactors .... 57
5. MATERIALS .................................................. 61
5.1. Finding low-cost, highly efficient materials ......... 61
5.2. Anode materials ...................................... 62
5.3. Membranes and separators (and chemical transport
through them) ........................................ 68
5.4. Cathode materials .................................... 76
5.5. Long-term stability of different materials ........... 83
6. ARCHITECTURE ............................................... 85
6.1. General requirements ................................. 85
6.2. Air-cathode MFCs ..................................... 86
6.3. Aqueous cathodes using dissolved oxygen .............. 95
6.4. Two-chamber reactors with soluble catholytes or
poised potentials .................................... 97
6.5. Tubular packed bed reactors ......................... 102
6.6. Stacked MFCs ........................................ 104
6.7. Metal catholytes .................................... 105
6.8. Biohydrogen MFCs .................................... 108
6.9. Towards a scalable MFC architecture ................. 110
7. KINETICS AND MASS TRANSFER ................................ 111
7.1. Kinetic-or mass transfer-based models? .............. 111
7.2. Boundaries on rate constants and bacterial
characteristics ..................................... 112
7.3. Maximum power from a monolayer of bacteria .......... 116
7.4. Maximum rate of mass transfer to a biofilm .......... 118
7.5. Mass transfer per reactor volume .................... 122
8. MECs FOR HYDROGEN PRODUCTION .............................. 125
8.1. Principle of operation .............................. 125
8.2. MEC systems ......................................... 127
8.3. Hydrogen yield ...................................... 131
8.4. Hydrogen recovery ................................... 132
8.5. Energy recovery ..................................... 134
8.6. Hydrogen losses ..................................... 142
8.7. Differences between the MEC and MFC systems ......... 145
9. MFCs FOR WASTEWATER TREATMENT ............................. 146
9.1. Process trains for WWTPs ............................ 146
9.2. Replacement of the biological treatment reactor
with an MFC ......................................... 149
9.3. Energy balances for WWTPs ........................... 154
9.4. Implications for reduced sludge generation .......... 157
9.5. Nutrient removal .................................... 158
9.6. Electrogenesis versus methanogenesis ................ 159
10. OTHER MFC TECHNOLOGIES .................................... 162
10.1. Different applications for MFC-based technologies ... 162
10.2. Sediment MFCs ....................................... 162
10.3. Enhanced sediment MFCs .............................. 166
10.4. Bioremediation using MFC technologies ............... 168
11. FUN! ...................................................... 171
11.1. MFCs for new scientists and inventors ............... 171
11.2. Choosing your inoculum and media .................... 174
11.3. MFC materials: electrodes and membranes ............. 175
11.4. MFC architectures that are easy to build ............ 176
11.5. MEC reactors ........................................ 180
11.6. Operation and assessment of MFCs .................... 181
12. OUTLOOK ................................................... 182
12.1. MFCs yesterday and today ............................ 182
12.2. Challenges for bringing MFCs to commercialization ... 183
12.3. Accomplishments and outlook ......................... 184
Notation ...................................................... 186
References .................................................... 189
Index ......................................................... 199
|
