Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes

Abstract

Microbial fuel cells (MiFCs) have been suggested as a means to harness energy that is otherwise unutilized during the wastewater treatment process. MiFCs have the unique ability to treat influent waste streams while simultaneously generating power which can offset energy associated with the biological treatment of wastewater. During the oxidation of organic and inorganic wastes, microorganisms known as exoelectrogens have the ability to move electrons extracellularly. MiFCs generate electricity by facilitating the microbial transfer of these electrons from soluble electron donors in feedstocks to a solid-state anode. While MiFCs are a promising renewable energy technology, current systems suffer from low power densities which hinder their practical applicability. In this study, a novel anode design using flame-deposited carbon nanostructures (CNSs) on stainless steel mesh is developed to improve the electron transfer efficiency of electrons from microorganisms to the anode and thus the power densities achievable by MiFCs. These new anodes appear to allow for increased biomass accumulation on the anode and may aid in the direct transfer of electrons to the anode in mediatorless MiFC systems. Experiments were conducted using anaerobic biomass in single-chamber MiFCs with CNS-enhanced and untreated stainless steel anodes. Fuel cells utilizing CNS-enhanced anodes generated currents up to two orders of magnitude greater than cells with untreated metal anodes, with the highest power density achieved being 510 mW m-2.