Wastewater treatment plants employ an energetically costly aerobic unit process to remove organic matter from municipal wastewater; this process is known as activated sludge. Microbial fuel cells (MFCs) present an anaerobic, energy-saving approach to wastewater treatment that results in electricity generation. However, MFCs are often limited by internal resistance from membrane fouling and slow cathodic oxygen reduction.

This work examined an option to overcome these limitations-- adapting membrane-less sediment microbial fuel cells (SMFCs) for use with wastewater as an organic substrate by using floating carbon cloth air cathodes coated with an oxygen reduction reaction (ORR) catalyst. The performance of a platinum ORR catalyst at the cathode was compared to a manganese dioxide ORR catalyst and several additional cathode materials and reactor configurations were tested to optimize SMFC performance. The MnO2 catalyst, though significantly cheaper than platinum, was unable to sustain consistent high cathode potentials in wastewater over time.