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

Abstract

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.

Comparative Evaluation of Coated and Non-Coated Carbon Electrodes in a Microbial Fuel Cell for Treatment of Municipal Sludge

“…An external resistor of 3.3 KΩ was used to monitor cell potential in the closed-circuit condition. Power values were derived using the formula P = IV [3,35], where (I) is the current generated and (V) is the potential measured at a certain resistance (R). For our studies, a galvanostatic scan was performed at a scan rate of 0.02 µA/s and the resulting voltage response was measured until the potential reached zero.…”

“…MFC technology is a low cost, sustainable, and promising waste management tool that has prompted extensive laboratory scale research on various parameters. Researchers have achieved chemical oxygen demand (COD) removal efficiencies of more than 90% [3], but the lower columbic efficiency (CE) and power density (PD) are the reason for its limited efficiency, compared to other conventional fuel cell technologies, and its commercial unavailability. Tremendous efforts have been made to understand and overcome the bottlenecks to achieving high performance MFC.…”

Industrial bioelectrochemistry for waste valorization: State of the art and challenges

“…The first pilot-scale MFC system reported was a modular reactor with a volume of 1 m 3 using brewery wastewater as feedstock (Waller and Trabold, 2013). After almost a decade, there are a few companies offering MFC or MEC solutions for wastewater treatment (Jadhav et al, 2022).…”

Moving bed capacitive bioanodes

“…This results in increased resistance in MFCs, which increases the voltage loss over the cell and limits the current density. As the ionic resistance is directly proportional to the width of the cell, a thin electrochemical cell is desired [79,80], since increasing the conductivity of the wastewater is not a practical option.…”

“…As described in the previous paragraph, a thin electrochemical cell is desired to reduce voltage losses. Suspended solids in wastewater streams form a challenge with thin spaces [79]. The anode and cathode compartments are often filled with porous structures, such as carbon felt [73,[81][82][83] or granules [84][85][86][87][88], to enhance the available surface area per volume, for biofilm attachment and reaction surface for hydrogen evolution, resulting in high current densities [80,89].…”