Review of Microbial Fuel Cells for Wastewater Treatment: Large-Scale Applications, Future Needs and Current Research Gaps

There is growing interest in innovative waste water treatment technologies that can utilize the inherent energy-producing potential of organic waste. A microbial fuel cell (MFC) is a type of bioreactor that produces electricity by converting energy in the chemical bonds of organic material, through a catalytic reaction of microorganisms under anaerobic conditions. MFCs provide a promising low cost, highly efficient, and renewable energy-producing alternative to conventional wastewater treatments. MFC technology at the laboratory scale has advanced to the point where chemical oxygen demand (COD) removal efficiencies (RE) over 90% are commonly achieved; however, low coulombic efficiencies (CE) and power densities often result when treating actual industrial and domestic wastewaters. In spite of their low energy recovery and power production, MFCs have been shown to be economically viable when factoring in costs savings from the sale of produced chemical byproducts and reduction of solid waste removal costs. However, further research of large-scale MFC wastewater treatment applications must be performed to determine the extent of their feasibility. This paper reviews several pilot-test MFC systems, addresses promising future industrial applications, and discusses current research gaps in MFC technology for wastewater treatment. Of particular interest in our research program is the use of MFCs to treat liquid-phase organic waste generated at food processing plants. Because of the general scalability of fuel cell systems, there is reason to believe that an MFC treatment system would be better suited to relatively small waste flow rates, unlike other treatment methods (e.g., anaerobic digestion) which typically require large volume to achieve economic viability.