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Book Details
Abstract
In the context of wastewater treatment, Bioelectrochemical Systems (BESs) have gained considerable interest in the past few years, and several BES processes are on the brink of application to this area. This book, written by a large number of world experts in the different sub-topics, describes the different aspects and processes relevant to their development.
Bioelectrochemical Systems (BESs) use micro-organisms to catalyze an oxidation and/or reduction reaction at an anodic and cathodic electrode respectively. Briefly, at an anode oxidation of organic and inorganic electron donors can occur. Prime examples of such electron donors are waste organics and sulfides. At the cathode, an electron acceptor such as oxygen or nitrate can be reduced. The anode and the cathode are connected through an electrical circuit. If electrical power is harvested from this circuit, the system is called a Microbial Fuel Cell; if electrical power is invested, the system is called a Microbial Electrolysis Cell.
The overall framework of bio-energy and bio-fuels is discussed. A number of chapters discuss the basics – microbiology, microbial ecology, electrochemistry, technology and materials development. The book continues by highlighting the plurality of processes based on BES technology already in existence, going from wastewater based reactors to sediment based bio-batteries. The integration of BESs into existing water or process lines is discussed. Finally, an outlook is provided of how BES will fit within the emerging biorefinery area.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Half title | 1 | ||
| Series | 2 | ||
| Title | 3 | ||
| Copyright | 4 | ||
| Contents | 5 | ||
| Foreword | 19 | ||
| List of Contributors | 21 | ||
| Chapter 1: Bioelectrochemical Systems: a new approach towards environmental and industrial biotechnology | 33 | ||
| 1.1 FUEL CELLS AND BIO-ELECTRICITY | 33 | ||
| 1.2 UNDERLYING PRINCIPLES | 37 | ||
| 1.2.1 Microorganisms and current | 37 | ||
| 1.2.2 Microbial communities in BESs | 38 | ||
| 1.2.3 From microbial metabolism to electrical current | 39 | ||
| 1.3 MEASURING AND DEFINING PERFORMANCE | 40 | ||
| 1.3.1 Measuring potentials | 41 | ||
| 1.3.2 Rate based performance indicators | 42 | ||
| 1.3.3 Efficiency based performance indicators | 42 | ||
| 1.4 A PLETHORA OF APPLICATIONS | 43 | ||
| 1.5 ACKNOWLEDGEMENTS | 44 | ||
| REFERENCES | 45 | ||
| Chapter 2: Microbial energy production from biomass | 49 | ||
| 2.1 BIOMASS: SOLAR ENERGY STORED IN ORGANIC MATERIAL | 49 | ||
| 2.2 THE ENERGY CONTENT OF BIOMASS | 52 | ||
| 2.3 BIO-ALCOHOL PRODUCTION FROM BIOMASS | 54 | ||
| 2.4 ANAEROBIC METHANOGENIC DIGESTION: WASTE STABILIZATION PLUS RENEWABLE ENERGY SOURCE | 56 | ||
| 2.4.1 Process performance | 56 | ||
| 2.4.2 The microbiology of methanogenesis | 58 | ||
| 2.4.3 The importance of extracellular electron transfer in AD | 59 | ||
| 2.4.4 Application of anaerobic digestion | 61 | ||
| 2.4.4.1 Anaerobic Digestion (AD) for solid waste | 61 | ||
| 2.4.4.2 AD for wastewater treatment | 62 | ||
| 2.4.4.3 Overall benefits and constraints of anaerobic digestion | 64 | ||
| 2.5 BIO-HYDROGEN PRODUCTION FROM BIOMASS | 66 | ||
| 2.6 FUTURE PERSPECTIVES | 67 | ||
| REFERENCES | 68 | ||
| Chapter 3: Enzymatic fuel cells and their complementarities relative to BES/MFC | 71 | ||
| 3.1 INTRODUCTION | 71 | ||
| 3.2 SIMILARITIES BETWEEN TYPES OF MICROBIAL AND ENZYMATIC BIOFUEL CELLS | 75 | ||
| 3.2.1 Bioreactor design | 76 | ||
| 3.2.2 In-situ bioreactor style | 76 | ||
| 3.2.3 Catalyst in anolyte solution | 77 | ||
| 3.2.4 Immobilized catalyst and/or mediator | 78 | ||
| 3.2.5 Direct electron transfer catalysts | 78 | ||
| 3.3 CATALYST SOURCES FOR MET AND DET SYSTEMS | 79 | ||
| 3.4 COMPARISON OF PROPERTIES OF MICROBIAL AND ENZYMATIC FUEL CELLS | 80 | ||
| 3.5 ENZYMES EMPLOYED IN ENZYMATIC BIOFUEL CELLS | 81 | ||
| 3.6 DEEP AND/OR COMPLETE OXIDATION OF FUEL | 84 | ||
| 3.7 CONCLUSIONS | 84 | ||
| 3.8 ACKNOWLEDGEMENTS | 85 | ||
| REFERENCES | 85 | ||
| Chapter 4: Shuttling via soluble compounds | 91 | ||
| 4.1 INTRODUCTION | 91 | ||
| 4.2 REDOX SHUTTLES | 93 | ||
| 4.3 EARLY EXPERIMENTS | 94 | ||
| 4.4 EXOGENOUS REDOX MEDIATORS | 95 | ||
| 4.4.1 Artificial mediators | 95 | ||
| 4.4.2 Natural redox mediators in the subsurface environment | 96 | ||
| 4.5 ENDOGENOUS REDOX MEDIATORS | 97 | ||
| 4.5.1 Known microbially produced redox mediators | 99 | ||
| 4.5.1.1 Phenazines | 99 | ||
| 4.5.1.2 Flavins | 99 | ||
| 4.5.1.3 Quinones | 100 | ||
| 4.5.1.4 Cytochromes and soluble enzymes | 101 | ||
| 4.5.1.5 Melanin | 101 | ||
| 4.5.1.6 Other mediators | 101 | ||
| 4.5.2 Unidentified endogenous mediators | 102 | ||
| 4.6 METHODS FOR IDENTIFICATION OF SOLUBLE REDOX SHUTTLES | 102 | ||
| 4.6.1 Potentiostat-controlled electrochemical cells | 103 | ||
| 4.6.2 Environmental conditions | 103 | ||
| 4.6.3 Batch experiments | 103 | ||
| 4.6.4 Media formulation | 103 | ||
| 4.6.5 Electrochemical methods | 103 | ||
| 4.6.6 Medium change | 104 | ||
| 4.6.7 Chemical structure of the mediator | 104 | ||
| 4.7 RELEVANCE OF SOLUBLE REDOX MEDIATORS SHUTTLE TO MICROBIAL METABOLISM | 104 | ||
| 4.8 SOLUBLE REDOX SHUTTLES IN BIOELECTROCHEMICAL DEVICES | 106 | ||
| 4.8.1 Microbial fuel cells | 106 | ||
| 4.8.1.1 Biosensors | 106 | ||
| 4.8.1.2 Electrodes modified with redox mediators | 107 | ||
| REFERENCES | 107 | ||
| Chapter 5: A survey of direct electron transfer from microbes to electronically active surfaces | 113 | ||
| 5.1 INTRODUCTION | 113 | ||
| 5.2 EXTRACELLULAR ELECTRON TRANSFER – MICROBIAL CONNECTIONS | 114 | ||
| 5.2.1 Localized sites for membrane associated EET | 115 | ||
| 5.2.1.1 Shewanella cytochromes | 115 | ||
| 5.2.1.2 Geobacter cytochromes | 117 | ||
| 5.2.2 Bacterial nanowires | 119 | ||
| 5.2.2.1 Geobacter nanowires | 120 | ||
| 5.2.2.2 Shewanella nanowires | 120 | ||
| 5.2.2.3 Nanowires produced by other microorganisms | 122 | ||
| 5.2.3 Nanowire characterization | 122 | ||
| 5.2.3.1 Composition | 123 | ||
| 5.2.3.2 Regulation | 123 | ||
| 5.2.3.3 Conductivity | 124 | ||
| 5.2.3.4 Function | 125 | ||
| 5.2.3.5 Prevalence | 125 | ||
| 5.3 ECOLOGICAL SIGNIFICANCE OF EXTRACELLULAR ELECTRON TRANSFER | 125 | ||
| REFERENCES | 127 | ||
| Chapter 6: Genetically modified microorganisms for bioelectrochemical systems | 133 | ||
| 6.1 INTRODUCTION | 133 | ||
| 6.2 EXTRACELLULAR RESPIRATION IN SHEWANELLA ONEIDENSIS AND GEOBACTER SULFURREDUCENS | 134 | ||
| 6.3 SCIENTIFIC MOTIVATION FOR HETEROLOGOUS GENE EXPRESSION | 137 | ||
| 6.4 METHODS AND CHALLENGES FOR HETEROLOGOUS GENE EXPRESSION IN E. COLI | 139 | ||
| 6.5 BIOTECHNOLOGICAL APPLICATIONS – DESIGNING THE ‘SUPER BUG’ | 142 | ||
| 6.5.1 The ‘super bug’ for BES applications | 142 | ||
| 6.5.2 The ‘super bug’ for bioremediation applications | 144 | ||
| 6.6 CLOSING REMARKS | 145 | ||
| 6.7 ACKNOWLEDGEMENTS | 145 | ||
| REFERENCES | 145 | ||
| Chapter 7: Electrochemical losses | 151 | ||
| 7.1 INTRODUCTION | 151 | ||
| 7.2 INDIVIDUAL ELECTROCHEMICAL LOSSES | 152 | ||
| 7.2.1 Activation polarization | 153 | ||
| 7.2.1.1 Means to decrease the activation polarization | 154 | ||
| 7.2.2 Ohmic polarization | 154 | ||
| 7.2.2.1 Means to decrease the ohmic polarization | 156 | ||
| 7.2.3 Concentration Polarization (Mass transfer and reaction polarization) | 157 | ||
| 7.2.3.1 Means to decrease the concentration polarization | 159 | ||
| 7.2.4 Reactant crossover – ‘internal currents’ | 159 | ||
| 7.2.4.1 Means to decrease internal current losses | 160 | ||
| 7.2.5 The pH splitting between anode and cathode | 161 | ||
| 7.2.5.1 Means to prevent the pH splitting | 161 | ||
| 7.3 METHODS | 161 | ||
| 7.3.1 Experimental strategies for the recording of polarization plots | 161 | ||
| 7.3.1.1 Current interrupt technique | 162 | ||
| 7.4 CONCLUSIONS | 163 | ||
| REFERENCES | 164 | ||
| Chapter 8: Electrochemical techniques for the analysis of bioelectrochemical systems | 167 | ||
| Chapter 8.1: Cyclic voltammetry for the study of microbial electron transfer at electrodes | 169 | ||
| 8.1.1 INTRODUCTION | 169 | ||
| 8.1.2 TURNOVER VS. NON-TURNOVER VOLTAMMETRY EXPERIMENTS | 172 | ||
| 8.1.2.1 General considerations | 172 | ||
| 8.1.2.2 Voltammetry in the presence of substrates | 173 | ||
| 8.1.2.3 Voltammetry in the absence of substrates | 177 | ||
| 8.1.2.4 Concluding remarks | 180 | ||
| REFERENCES | 180 | ||
| Chapter 8.2: Importance of Tafel plots in the investigation of bioelectrochemical systems | 185 | ||
| 8.2.1 INTRODUCTION | 185 | ||
| 8.2.2 USE OF TAFEL PLOTS FOR PERFORMANCE EVALUATION OF MICROBIAL FUEL CELLS | 188 | ||
| 8.2.2.1 Tafel plots for monitoring the electrocatalytic activity of anode materials toward microbial consortia | 189 | ||
| 8.2.2.2 Tafel plots for examining charge transfer with microbial pure cultures | 194 | ||
| 8.2.2.3 Estimating the maximum power production from Tafel plots | 195 | ||
| REFERENCES | 197 | ||
| Chapter 8.3: The use of electrochemical impedance spectroscopy (EIS) for the evaluation of the electrochemical properties of bioelectrochemical systems | 201 | ||
| 8.3.1 INTRODUCTION | 201 | ||
| 8.3.2 INSTRUMENTATION AND EXPERIMENTAL APPROACH | 202 | ||
| 8.3.3 DISPLAY AND ANALYSIS OF EIS DATA | 204 | ||
| 8.3.4 DETERMINATION OF KEY ELECTROCHEMICAL PARAMETERS FROM IMPEDANCE SPECTRA | 207 | ||
| 8.3.5 APPLICATIONS OF ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY IN THE STUDY OF MFCS | 208 | ||
| 8.3.5.1 Electrochemical characterization of anode and cathode properties | 208 | ||
| 8.3.5.2 Determination and analysis of the internal resistance R⊂in | 211 | ||
| 8.3.6 CONCLUSIONS | 213 | ||
| REFERENCES | 213 | ||
| Chapter 9: Materials for BES | 217 | ||
| 9.1 INTRODUCTION | 217 | ||
| 9.1.1 Electrode specific surface areas and material costs | 219 | ||
| 9.2 ELECTRODE MATERIALS FOR MFCS | 219 | ||
| 9.2.1 Anode | 219 | ||
| 9.2.2 Cathode | 221 | ||
| 9.2.3 Membranes | 225 | ||
| 9.3 OTHER MATERIALS | 229 | ||
| 9.3.1 Current collectors | 229 | ||
| 9.3.2 Wires, resistors and loads | 229 | ||
| 9.4 MATERIALS FOR MICROBIAL ELECTROLYSIS CELLS | 230 | ||
| 9.5 CONCLUSIONS AND OUTLOOK | 232 | ||
| REFERENCES | 233 | ||
| Chapter 10: Technological factors affecting BES performance and bottlenecks towards scale up | 237 | ||
| 10.1 INTRODUCTION | 237 | ||
| 10.2 DESIGN CONSTRAINTS AS DETERMINED BY WASTEWATER APPLICATION | 239 | ||
| 10.2.1 Footprint and energetic efficiency | 239 | ||
| 10.2.2 Effect of conductivity | 242 | ||
| 10.2.3 Effect of buffer capacity | 244 | ||
| 10.2.4 Membrane separator or not | 244 | ||
| 10.3 DESIGN CONSTRAINTS AS DETERMINED BY SCALE UP | 245 | ||
| 10.3.1 Scale up and voltage losses | 245 | ||
| 10.3.2 Hydrodynamics and mechanics | 247 | ||
| 10.4 COSTS AND CHOICE OF MATERIALS | 247 | ||
| 10.4.1 Material properties and costs | 247 | ||
| 10.4.2 Anode | 248 | ||
| 10.4.3 Cathode | 249 | ||
| 10.4.4 Membranes | 249 | ||
| 10.5 OVERCOMING DESIGN CONSTRAINTS | 250 | ||
| 10.5.1 Constraints and solutions | 250 | ||
| REFERENCES | 252 | ||
| Chapter 11: Organics oxidation | 257 | ||
| 11.1 INTRODUCTION | 257 | ||
| 11.2 RESPIRATORY OXIDATION TO CARBON DIOXIDE | 260 | ||
| 11.3 FERMENTATION AT MICROBIAL FUEL CELL ANODES | 263 | ||
| 11.4 SYNTROPHY BETWEEN FERMENTERS AND ANODOPHILES | 266 | ||
| 11.5 METHANOGENS COMPETE FOR FERMENTATION PRODUCTS | 268 | ||
| 11.6 ELECTROCATALYTIC OXIDATION OF FERMENTATION PRODUCTS | 269 | ||
| 11.7 SUMMARY | 270 | ||
| REFERENCES | 271 | ||
| Chapter 12: Conversion of sulfur species in bioelectrochemical systems | 275 | ||
| 12.1 INTRODUCTION | 275 | ||
| 12.2 PROPERTIES OF SULFUR SPECIES | 276 | ||
| 12.2.1 Elemental sulfur | 276 | ||
| 12.2.2 Sulfide and polysulfides | 276 | ||
| 12.2.3 Sulfate and other oxyanions | 277 | ||
| 12.2.4 Relationship of electrochemical potential and pH for sulfur species in aqueous systems | 277 | ||
| 12.3 EXISTING SULFIDE AND SULFATE REMOVAL TECHNOLOGIES | 279 | ||
| 12.3.1 Sulfide removal technologies | 279 | ||
| 12.3.1.1 Physicochemical processes | 280 | ||
| 12.3.1.2 Biological technologies | 280 | ||
| 12.3.2 Sulfate removal technologies | 281 | ||
| 12.3.3 Evaluation of existing technologies | 281 | ||
| 12.4 ABIOTIC ELECTROCHEMICAL REMOVAL OF AQUEOUS SULFIDE | 282 | ||
| 12.4.1 Introduction | 282 | ||
| 12.4.2 Spontaneous sulfide oxidation and electricity generation | 284 | ||
| 12.4.3 Final product of sulfide oxidation | 284 | ||
| 12.4.4 Properties of electrodeposited sulfur | 286 | ||
| 12.5 REMOVAL OF AQUEOUS SULFIDE IN BES | 288 | ||
| 12.5.1 Introduction | 288 | ||
| 12.5.2 Sulfide oxidation in a biotic cell | 289 | ||
| 12.6 OUTLOOK | 290 | ||
| REFERENCES | 291 | ||
| Chapter 13: Chemically catalyzed cathodes in bioelectrochemical systems | 295 | ||
| 13.1 INTRODUCTION | 295 | ||
| 13.2 OXYGEN REDUCTION REACTION (ORR) | 297 | ||
| 13.2.1 Introduction | 297 | ||
| 13.2.2 Oxygen reduction catalysts | 299 | ||
| 13.2.2.1 Platinum | 299 | ||
| 13.2.2.2 Transition metal macrocycle based catalysts | 300 | ||
| 13.2.2.3 Metal oxides | 300 | ||
| 13.2.2.4 Enzymes | 301 | ||
| 13.2.3 MFC cathode configurations | 301 | ||
| 13.2.3.1 Aqueous cathodes | 301 | ||
| 13.2.3.2 Air cathodes | 301 | ||
| 13.3 HYDROGEN EVOLUTION REACTION (HER) | 302 | ||
| 13.3.1 Introduction | 302 | ||
| 13.3.2 Hydrogen evolution catalysts | 306 | ||
| 13.3.2.1 Platinum | 306 | ||
| 13.3.2.2 Nickel | 308 | ||
| 13.3.2.3 Tungsten carbide | 308 | ||
| 13.3.2.4 Enzymes | 309 | ||
| 13.3.3 MEC cathode configurations | 309 | ||
| 13.3.3.1 Aqueous cathodes | 309 | ||
| 13.3.3.2 Gas diffusion cathodes | 310 | ||
| 13.4 FUTURE POSSIBILITIES | 311 | ||
| REFERENCES | 312 | ||
| Chapter 14: Bioelectrochemical reductions in reactor systems | 317 | ||
| 14.1 INTRODUCTION | 317 | ||
| 14.2 AEROBIC BIOCATHODES | 318 | ||
| 14.3 ANOXIC AND ANAEROBIC BIOCATHODES | 321 | ||
| 14.4 ELECTRON TRANSFER IN BIOCATHODES | 326 | ||
| 14.5 LIMITING FACTORS | 329 | ||
| 14.6 OUTLOOK | 330 | ||
| 14.7 ACKNOWLEDGEMENTS | 331 | ||
| REFERENCES | 331 | ||
| Chapter 15: Bioelectrochemical systems (BES) for subsurface remediation | 337 | ||
| 15.1 BIOREMEDIATION OF CONTAMINATED SOILS AND AQUIFERS | 337 | ||
| 15.2 CHEMICAL VS. ELECTROCHEMICAL STRATEGIES OF ELECTRON DELIVERY | 338 | ||
| 15.2.1 Chlorinated hydrocarbons | 341 | ||
| 15.2.2 Inorganic pollutants | 347 | ||
| 15.3 OUTLOOKS, PERSPECTIVES, AND CHALLENGES TOWARDS FIELD APPLICATIONS | 351 | ||
| REFERENCES | 354 | ||
| Chapter 16: Fundamentals of benthic microbial fuel cells: theory, development and application | 359 | ||
| 16.1 INTRODUCTION | 359 | ||
| 16.2 FUNDAMENTAL PRINCIPLES OF SEDIMENT REDUCTION-OXIDATION CHEMISTRY | 360 | ||
| 16.3 PRINCIPLES OF DESIGN AND APPROACHES TO TESTING BENTHIC MICROBIAL FUEL CELLS (BMFCs) | 361 | ||
| 16.4 ANODE MATERIAL AND DESIGN | 362 | ||
| 16.5 CATHODE MATERIALS AND DESIGN | 364 | ||
| 16.6 PERFORMANCE AND PRACTICAL CONSIDERATIONS OF BMFC DESIGNS | 365 | ||
| 16.7 MICROBIAL ECOLOGY OF BMFCs | 367 | ||
| 16.8 FACTORS GOVERNING POWER OUTPUT | 370 | ||
| 16.9 SCALING AND ENVIRONMENTAL VARIABILITY IN BMFCs | 372 | ||
| 16.10 COMMERCIAL VIABILITY OF BMFCs | 373 | ||
| REFERENCES | 375 | ||
| Chapter 17: Microbial fuel cells as biochemical oxygen demand (BOD) and toxicity sensors | 379 | ||
| 17.1 INTRODUCTION | 379 | ||
| 17.1.1 Dissolved oxygen probe-based BOD sensors | 380 | ||
| 17.1.2 Photometric BOD sensors | 380 | ||
| 17.1.3 Titration and respirometric sensors | 381 | ||
| 17.1.4 Electrochemical BOD sensors with mediators | 381 | ||
| 17.2 THE MEDIATOR-LESS MICROBIAL FUEL CELL | 383 | ||
| 17.2.1 Electrochemically-active bacteria | 383 | ||
| 17.2.2 Enrichment of an electrochemically-active bacterial community | 384 | ||
| 17.2.3 Microbiology of a mediator-less MFC | 385 | ||
| 17.2.4 Optimization of MFC performance | 385 | ||
| 17.3 DESIGN AND PERFORMANCE OF AN MFC USED AS BOD SENSOR | 387 | ||
| 17.3.1 MFC to measure BOD values higher than 10 mg/L | 388 | ||
| 17.3.1.1 MFC design | 388 | ||
| 17.3.1.2 Enrichment and operation | 389 | ||
| 17.3.1.3 Performance | 390 | ||
| 17.3.2 MFC to measure BOD values lower than 10 mg/l | 391 | ||
| 17.3.2.1 Background | 391 | ||
| 17.3.2.2 Oligotrophic sensor design and performance | 391 | ||
| 17.3.3 BOD determination of samples containing oxygen and nitrate | 392 | ||
| 17.3.3.1 Oxygen and nitrate reduce current and coulombic efficiency | 392 | ||
| 17.3.3.2 Use of respiratory inhibitors | 392 | ||
| 17.4 MFC AS A TOXICITY SENSOR | 393 | ||
| 17.5 CONCLUSIONS | 393 | ||
| 17.6 ACKNOWLEDGEMENTS | 393 | ||
| REFERENCES | 394 | ||
| Chapter 18: Feedstocks for BES conversions | 401 | ||
| 18.1 INTRODUCTION | 401 | ||
| 18.2 DEFINED SUBSTRATES UTILIZED BY BES | 404 | ||
| 18.2.1 Volatile fatty acids and other fermentation end products | 404 | ||
| 18.2.2 Soluble carbohydrates, amino acids and xenobiotics | 408 | ||
| 18.3 COMPLEX SUBSTRATES AND WASTEWATERS UTILIZED BY BES | 409 | ||
| 18.3.1 Cellulosic feedstocks | 410 | ||
| 18.3.2 Chitin | 411 | ||
| 18.3.3 Domestic wastewater | 411 | ||
| 18.3.4 Simulated and actual industrial wastewaters | 411 | ||
| 18.4 OTHER ASPECTS OF FEEDSTOCK COMPOSITION | 413 | ||
| 18.5 FEEDSTOCKS AND BES INTEGRATION IN WASTEWATER TREATMENT PROCESSES | 415 | ||
| 18.6 CONCLUSIONS | 419 | ||
| 18.7 ACKNOWLEDGEMENTS | 420 | ||
| REFERENCES | 420 | ||
| Chapter 19: Integrating BES in the wastewater and sludge treatment line | 425 | ||
| 19.1 INTRODUCTION | 425 | ||
| 19.2 BES AS THE SINGLE BIOLOGICAL TREATMENT UNIT (A) OR FOLLOWED BY AN ACTIVATED SLUDGE SYTEM AS A POLISHING STEP (B) | 428 | ||
| 19.3 PREACIDIFICATION OF ORGANIC WASTEWATER BEFORE BES (C) | 430 | ||
| 19.4 ANAEROBIC DIGESTERS FOR SLUDGE STABILIZATION FOLLOWED BY BES (D) | 431 | ||
| 19.5 GENERATING CAUSTIC IN THE CATHODE OF BES TO CONTROL ANAEROBIC DIGESTER pH (E) | 433 | ||
| 19.6 DENITRIFICATON IN THE CATHODE OF BES TO REMOVE NUTRIENTS FROM WATER (F) | 434 | ||
| 19.7 GENERATING CHEMICAL REAGENTS AT CATHODES FOR TREATMENT PURPOSES (G) | 435 | ||
| 19.8 OUTLOOK | 436 | ||
| 19.9 ACKNOWLEDGEMENTS | 437 | ||
| REFERENCES | 437 | ||
| Chapter 20: Peripherals of BES – small scale yet feasible (demonstrated) applications | 441 | ||
| 20.1 INTRODUCTION | 441 | ||
| 20.2 ARTIFICIAL SYMBIOSIS | 442 | ||
| 20.3 MICROBIAL FUEL CELLS AND THEIR CONFIGURATIONS | 443 | ||
| 20.3.1 Definition of peripherals | 443 | ||
| 20.3.2 Bridging the power divide | 444 | ||
| 20.3.3 Minimal peripheral requirements for continuous and autonomous operation | 447 | ||
| 20.3.4 Complexity in stacks | 448 | ||
| 20.3.5 Microbial Electrolysis Cells (MECs) that transform organic feedstocks into other types of energy (hydrogen or methane) but require input of electrical power in the process | 451 | ||
| 20.3.6 Microbial Electrolysis Cells (MECs) that consume electrical power to drive useful reactions (e.g. denitrification) | 452 | ||
| REFERENCES | 452 | ||
| Chapter 21: Towards a mathematical description of bioelectrochemical systems | 455 | ||
| 21.1 INTRODUCTION | 455 | ||
| 21.2 MATHEMATICAL MODELLING | 456 | ||
| 21.2.1 Model characteristics | 457 | ||
| 21.2.1.1 Mechanistics vs. empirism | 457 | ||
| 21.2.1.2 Dynamic vs. stationary models | 458 | ||
| 21.2.1.3 Level of segregation/aggregation | 458 | ||
| 21.2.2 How do model characteristics affect the model user? | 459 | ||
| 21.3 BESs MODELLING OBJECTIVES | 459 | ||
| 21.4 KEY ELEMENTS FOR BESs MODELLING | 461 | ||
| 21.5 EXISTING BESs MODELS | 461 | ||
| 21.6 CURRENT CHALLENGES IN BESs MODELLING | 468 | ||
| 21.6.1 Bioelectrode kinetics | 469 | ||
| 21.6.2 Electron transfer mechanisms | 471 | ||
| 21.6.3 Microbial activity: bioenergetics and kinetics | 472 | ||
| 21.6.4 Mass transport – convection, diffusion and migration | 475 | ||
| 21.6.5 Biofilm and spatial modelling | 476 | ||
| 21.7 BESs MODELLING PERSPECTIVES | 477 | ||
| 21.8 ACKNOWLEDGEMENTS | 478 | ||
| REFERENCES | 478 | ||
| Outlook: Research directions and new applications for BES | 481 | ||
| 22.1 BES RESEARCH – FOCUS ON THE APPLICATION | 481 | ||
| 22.2 FUNDAMENTAL RESEARCH DIRECTIONS | 482 | ||
| 22.2.1 Understanding bioelectrochemical process fundamentals | 482 | ||
| 22.2.2 Practically inspired fundamental research areas | 484 | ||
| 22.3 APPLIED RESEARCH OPPORTUNITIES | 485 | ||
| 22.3.1 Contributions and limitations of current research activities | 485 | ||
| 22.3.2 BESs for wastewater treatment? | 487 | ||
| 22.3.3 Is power the best product from BESs? | 488 | ||
| 22.4 POTENTIAL NEW BES APPLICATIONS | 489 | ||
| 22.4.1 Novel options for cathodic reductions | 489 | ||
| 22.4.2 Novel options for anodic oxidations | 491 | ||
| 22.5 BES INTEGRATION INTO PRACTICAL APPLICATIONS | 491 | ||
| 22.6 CONCLUDING THOUGHTS ON THE FUTURE OF BES | 493 | ||
| REFERENCES | 494 | ||
| Index | 499 |