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Electro-osmotic-based catholyte production by Microbial Fuel Cells for carbon capture
Iwona Gajda1, John Greenman2, Chris Melhuish1
1Bristol BioEnergy Centre, Bristol Robotics Laboratory, Block T, UWE, Coldharbour Lane, Bristol BS16 1QY, UK.
Water Research
|September 7, 2015
Summary
Microbial Fuel Cells (MFCs) generate caustic catholyte from wastewater, with activated carbon cathodes producing high pH liquid and power. This process demonstrates effective water recovery and carbon capture, enhancing wastewater treatment sustainability.
Area of Science:
- Electrochemistry
- Environmental Science
- Materials Science
Background:
- Microbial Fuel Cells (MFCs) utilize microbial activity to generate electricity.
- Water recovery in MFCs involves active (electro-osmosis) and passive (osmosis) transport through separators.
- Wastewater treatment can be enhanced by MFC technology.
Purpose of the Study:
- To investigate caustic catholyte production on cathode surfaces in MFCs.
- To understand the roles of active and passive transport mechanisms in catholyte formation.
- To evaluate the carbon capture potential of MFCs with Pt-free carbon electrodes.
Main Methods:
- Utilizing wastewater as fuel in MFCs with Pt-free activated carbon cathodes.
- Measuring pH, power output, and analyzing catholyte composition.
- Comparing transport mechanisms under open and closed circuit conditions.
Main Results:
- Highest pH (>13) and power (309 μW) achieved with activated carbon cathodes.
- Active transport dominated under closed circuits, correlating linearly with power.
- Passive (osmotic) transport governed liquid flux under open circuits.
- Caustic catholyte formation led to mineralisation into trona (carbonate/bicarbonate salts), indicating carbon capture.
Conclusions:
- MFCs can produce valuable caustic catholyte and recover water.
- Activated carbon cathodes enhance MFC power generation and catholyte alkalinity.
- MFCs offer a sustainable wastewater treatment method with inherent carbon capture capabilities.
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