Continuous microbial fuel cells convert carbohydratesto electricity

Abstract

Microbial fuel cells which are operated in continuous mode are more suitable for practical applications than fed batch ones. Three influent types containing carbohydrates were tested, i.e. a glucose medium, a plant extract and artificial wastewater. The anode reactor compartment yielding the best results was a packed bed reactor containing graphite granules. While in non-mediated batch systems power outputs up to 479 W m⁻³ of anode compartment could be attained; in continuous mode the power outputs were limited to 49 W m⁻³. Cyclic voltammetry was performed to determine the potential of the in-situ synthesized bacterial redox mediators. Addition of mediators with a potential similar to the bacterial potential did not significantly alter the MFC power output, indicating a limited influence of soluble mediators for continuous microbial fuel cells. Maximum coulombic and energy conversion efficiencies were, for the continuous microbial fuel cell operating on plant extract at a loading rate of 1 kg COD m⁻³ of anode compartment per day, 50.3% and 26.0% respectively.

Key findings

• ▸Continuous MFCs have lower power outputs (49 W m⁻³) compared to batch systems (up to 479 W m⁻³).
• ▸The addition of mediators with a potential similar to the bacterial potential did not significantly alter the MFC power output.
• ▸Maximum coulombic and energy conversion efficiencies were 50.3% and 26.0%, respectively, for a continuous MFC operating on plant extract.

Keywords

Identifiers

DOI

10.2166/wst.2005.0561

Journal

Water Science and Technology

Year

2005