Treatment of domestic wastewater with simultaneous electricity generation in microbial fuel cell under continuous operation

In order to apply microbial fuel cell (MFC) process more practically in wastewater treatment, both power generation and removal of chemical oxygen demand (COD) were examined in an air-cathode MFC fed with domestic wastewater under continuous operation. At a hydraulic retention time (HRT) of 2.0 h, the air-cathode MFC was able to generate electricity from domestic wastewater with a maximum power density of P = 103 ± 2 mW m^-2 (5772 mW m ^-3) and an average Coulomb efficiency (CE) of 18.4 %; meanwhile, to achieve an average COD removal up to 71 %. Increasing HRT from 2h to 10-30 h was found to be more effective for COD removal, however, instability in voltage output was also observed. An increased power generation of 173±4 mW m^-2 (9648 mW m^-3) was obtained with the aid of NaCl addition at a mass fraction of w = 2.4 %, because of an elevated conductivity of the solution with accord internal resistance of 227 Ω.