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Gajda I.,Bristol BioEnergy Center | Greenman J.,Bristol BioEnergy Center | Melhuish C.,Bristol BioEnergy Center | Santoro C.,University of Connecticut | And 4 more authors.
Water Research | Year: 2015

In Microbial Fuel Cells (MFCs), the recovery of water can be achieved with the help of both active (electro-osmosis), and passive (osmosis) transport pathways of electrolyte through the semi-permeable selective separator. The electrical current-dependent transport, results in cations and electro-osmotically dragged water molecules reaching the cathode. The present study reports on the production of catholyte on the surface of the cathode, which was achieved as a direct result of electricity generation using MFCs fed with wastewater, and employing Pt-free carbon based cathode electrodes. The highest pH levels (>13) of produced liquid were achieved by the MFCs with the activated carbon cathodes producing the highest power (309 μW). Caustic catholyte formation is presented in the context of beneficial cathode flooding and transport mechanisms, in an attempt to understand the effects of active and passive diffusion. Active transport was dominant under closed circuit conditions and showed a linear correlation with power performance, whereas osmotic (passive) transport was governing the passive flux of liquid in open circuit conditions. Caustic catholyte was mineralised to a mixture of carbonate and bicarbonate salts (trona) thus demonstrating an active carbon capture mechanism as a result of the MFC energy-generating performance. Carbon capture would be valuable for establishing a carbon negative economy and environmental sustainability of the wastewater treatment process. © 2015 The Authors.


PubMed | RSE Ricerca sul Sistema Energetico S.p.A., University of New Mexico, Bristol BioEnergy Center and University of Connecticut
Type: | Journal: Water research | Year: 2015

In Microbial Fuel Cells (MFCs), the recovery of water can be achieved with the help of both active (electro-osmosis), and passive (osmosis) transport pathways of electrolyte through the semi-permeable selective separator. The electrical current-dependent transport, results in cations and electro-osmotically dragged water molecules reaching the cathode. The present study reports on the production of catholyte on the surface of the cathode, which was achieved as a direct result of electricity generation using MFCs fed with wastewater, and employing Pt-free carbon based cathode electrodes. The highest pH levels (>13) of produced liquid were achieved by the MFCs with the activated carbon cathodes producing the highest power (309 W). Caustic catholyte formation is presented in the context of beneficial cathode flooding and transport mechanisms, in an attempt to understand the effects of active and passive diffusion. Active transport was dominant under closed circuit conditions and showed a linear correlation with power performance, whereas osmotic (passive) transport was governing the passive flux of liquid in open circuit conditions. Caustic catholyte was mineralised to a mixture of carbonate and bicarbonate salts (trona) thus demonstrating an active carbon capture mechanism as a result of the MFC energy-generating performance. Carbon capture would be valuable for establishing a carbon negative economy and environmental sustainability of the wastewater treatment process.


Salar-Garcia M.J.,Technical University of Cartagena | Gajda I.,Bristol BioEnergy Center | Ortiz-Martinez V.M.,Technical University of Cartagena | Greenman J.,Bristol BioEnergy Center | And 3 more authors.
Bioresource Technology | Year: 2016

In this work, the by-product generated during the operation of cylindrical MFCs, made out of terracotta material, is investigated as a feasible means of degrading live microalgae for the first time. In addition to the low cost materials of this design, the reuse of the solution produced in the cathode renders the technology truly green and capable of generating bioenergy. In this study, the effect of a light/dark cycle or dark conditions only on the digestion of live microalgae with the catholyte is investigated. The results show that a combination of light/dark improves degradation and allows algae to be used as substrate in the anode. The addition of 12.5. mL of a 1:1 mix of catholyte and microalgae (pre-digested over 5. days under light/dark) to the anode, increases the power generation from 7. μW to 44. μW once all the organic matter in the anode had been depleted. © 2016 Elsevier Ltd.


PubMed | University of Trento, Technical University of Cartagena, University of Murcia and Bristol BioEnergy Center
Type: | Journal: Bioresource technology | Year: 2016

In this work, the by-product generated during the operation of cylindrical MFCs, made out of terracotta material, is investigated as a feasible means of degrading live microalgae for the first time. In addition to the low cost materials of this design, the reuse of the solution produced in the cathode renders the technology truly green and capable of generating bioenergy. In this study, the effect of a light/dark cycle or dark conditions only on the digestion of live microalgae with the catholyte is investigated. The results show that a combination of light/dark improves degradation and allows algae to be used as substrate in the anode. The addition of 12.5mL of a 1:1 mix of catholyte and microalgae (pre-digested over 5days under light/dark) to the anode, increases the power generation from 7W to 44W once all the organic matter in the anode had been depleted.


Gajda I.,Bristol BioEnergy Center | Greenman J.,Bristol BioEnergy Center | Melhuish C.,Bristol BioEnergy Center | Ieropoulos I.,Bristol BioEnergy Center
Biomass and Bioenergy | Year: 2015

This paper describes the potential for algal biomass production in conjunction with wastewater treatment and power generation within a fully biotic Microbial Fuel Cell (MFC). The anaerobic biofilm in the anodic half-cell is generating current, whereas the phototrophic biofilm on the cathode is providing the oxygen for the Oxygen Reduction Reaction (ORR) and forming biomass. The MFC is producing electricity with simultaneous biomass regeneration in the cathodic half-cell, which is dependent on the nutrient value of the anodic feedstock. Growth of algal biomass in the cathode was monitored, assessed and compared against the MFC power production (charge transfer), during this process. MFC generation of electricity activated the cation crossover for the formation of biomass, which has been harvested and reused as energy source in a closed loop system. It can be concluded that the nutrient reclamation and assimilation into new biomass increases the energy efficiency. This work is presenting a simple and self-sustainable MFC operation with minimal dependency on chemicals and an energy generation system utilising waste products and maximising energy turnover through an additional biomass recovery. © 2015 Elsevier Ltd.


Houghton J.,University of New Mexico | Santoro C.,University of New Mexico | Soavi F.,University of Bologna | Serov A.,University of New Mexico | And 3 more authors.
Bioresource Technology | Year: 2016

Supercapacitive microbial fuel cells with various anode and cathode dimensions were investigated in order to determine the effect on cell capacitance and delivered power quality. The cathode size was shown to be the limiting component of the system in contrast to anode size. By doubling the cathode area, the peak power output was improved by roughly 120% for a 10 ms pulse discharge and internal resistance of the cell was decreased by ∼47%. A model was constructed in order to predict the performance of a hypothetical cylindrical MFC design with larger relative cathode size. It was found that a small device based on conventional materials with a volume of approximately 21 cm3 would be capable of delivering a peak power output of approximately 25 mW at 70 mA, corresponding to ∼1300 W m−3. © 2016 The Author(s)


Gajda I.,Bristol BioEnergy Center | Greenman J.,Bristol BioEnergy Center | Melhuish C.,Bristol BioEnergy Center | Ieropoulos I.,Bristol BioEnergy Center
Bioelectrochemistry | Year: 2015

To date, the development of microbially assisted synthesis in Bioelectrochemical Systems (BESs) has focused on mechanisms that consume energy in order to drive the electrosynthesis process. This work reports - for the first time - on novel ceramic MFC systems that generate electricity whilst simultaneously driving the electrosynthesis of useful chemical products. A novel, inexpensive and low maintenance MFC demonstrated electrical power production and implementation into a practical application. Terracotta based tubular MFCs were able to produce sufficient power to operate an LED continuously over a 7day period with a concomitant 92% COD reduction. Whilst the MFCs were generating energy, an alkaline solution was produced on the cathode that was directly related to the amount of power generated. The alkaline catholyte was able to fix CO2 into carbonate/bicarbonate salts. This approach implies carbon capture and storage (CCS), effectively capturing CO2 through wet caustic 'scrubbing' on the cathode, which ultimately locks carbon dioxide. © 2015 Elsevier B.V.


Gajda I.,Bristol BioEnergy Center | Stinchcombe A.,Bristol BioEnergy Center | Greenman J.,Bristol BioEnergy Center | Greenman J.,University of the West of England | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2015

This communication reports on the potential of using MFCs for powering real world applications, whereby three interconnected MFCs directly energise an external DC motor, and a single MFC recharges a mobile phone, via energy harvesting. The work is aiming to evaluate MFC performance based on low-cost, catalyst-free conditions, with an internal cathode to operate practical applications. It presents the case for simple and easy-tooperate ceramic-based designs as a viable approach to larger-scale implementation in real-world conditions such as wastewater treatment plants. MFCs hold great promise for sustainable wastewater treatment since they are the only technology that directly generates electricity from the break-down of waste. © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


PubMed | University of Bologna, Bristol BioEnergy Center and University of New Mexico
Type: | Journal: Bioresource technology | Year: 2016

Supercapacitive microbial fuel cells with various anode and cathode dimensions were investigated in order to determine the effect on cell capacitance and delivered power quality. The cathode size was shown to be the limiting component of the system in contrast to anode size. By doubling the cathode area, the peak power output was improved by roughly 120% for a 10ms pulse discharge and internal resistance of the cell was decreased by 47%. A model was constructed in order to predict the performance of a hypothetical cylindrical MFC design with larger relative cathode size. It was found that a small device based on conventional materials with a volume of approximately 21cm(3) would be capable of delivering a peak power output of approximately 25mW at 70mA, corresponding to 1300Wm(-3).


PubMed | Bristol BioEnergy Center
Type: | Journal: Bioelectrochemistry (Amsterdam, Netherlands) | Year: 2015

To date, the development of microbially assisted synthesis in Bioelectrochemical Systems (BESs) has focused on mechanisms that consume energy in order to drive the electrosynthesis process. This work reports--for the first time--on novel ceramic MFC systems that generate electricity whilst simultaneously driving the electrosynthesis of useful chemical products. A novel, inexpensive and low maintenance MFC demonstrated electrical power production and implementation into a practical application. Terracotta based tubular MFCs were able to produce sufficient power to operate an LED continuously over a 7 day period with a concomitant 92% COD reduction. Whilst the MFCs were generating energy, an alkaline solution was produced on the cathode that was directly related to the amount of power generated. The alkaline catholyte was able to fix CO2 into carbonate/bicarbonate salts. This approach implies carbon capture and storage (CCS), effectively capturing CO2 through wet caustic scrubbing on the cathode, which ultimately locks carbon dioxide.

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