Integrated organic and nitrogen removal with electricity generation in a tubular dual-cathode microbial fuel cell

Abstract

This study presented a dual-cathode microbial fuel cell (MFC) that was designed to accomplish nitrification in its outer cathode and denitrification in the inner cathode. The MFC was continuously operated for more than 150 days and achieved organic removal of 85–99% in the anode, depending on the initial organic loading rates. More than 96% of the ammonium was removed, while the total nitrogen removal was between 66.7 and 89.6%, largely affected by the remaining nitrate in the effluent of the inner cathode. The coulombic efficiency suggested that the nitrate was primarily removed by bioelectrochemcial denitrification in the inner cathode, especially at the low nitrogen loading rates. However, a higher nitrogen loading rate encouraged nitrate migration through the anion exchange membrane, thereby being removed by conventional denitrification. The preliminary energy analysis suggested that the energy production in the dual-cathode MFC could potentially support its pumping system. To achieve an energy-neutral system, aeration must be omitted in the future design and passive oxygen supply should be considered with a proper design of the outer cathode. Those results demonstrated the feasibility of using a tubular dual-cathode MFC to remove both organics and nitrogen while producing electricity.