Animal carcass wastewater treatment and bioelectricity generation in up-flow tubular microbial fuel cells: Effects of HRT and non-precious metallic catalyst

Animal carcass wastewater (ACW) is a kind of typical high concentration organic wastewater. Up-flow tubular air cathode microbial fuel cells (MFCs) were constructed using 0, 4.0 and 8.0 mg/cm2 MnO2 as cathodic catalyst, respectively (MFC-0, MFC-4 and MFC-8) to test the feasibility of bioelectricity production from ACW. After a start-up period of around 55d, when hydraulic retention time (HRT) was set at 3d, MFC-4 showed best bioelectricity performance with the maximum power density of 2.19 W/m3 and minimum internal resistance of 30.3 Ω, as compared to MFC-0 (1.14 W/m3, 62.6 Ω) and MFC-8 (1.49 W/m3, 34.5 Ω). Chemical oxygen demand (COD) and nitrate removal efficiencies of MFC-4 were 50.66% and 79.76%, respectively. Switching HRT from 3d to 6d, COD and nitrate removal efficiencies sped up while the increase rates of ammonia slowed down. The results demonstrated that ACW could be the fuel of MFCs to generate bioelectricity.