Microbial fuel cells (MFCs) represent a new method for treating animal wastewaters and simultaneously producing electricity. Preliminary tests using a two-chambered MFC with an aqueous cathode indicated that electricity could be generated from swine wastewater containing 83207190 mg/L of soluble chemical oxygen demand (SCOD) (maximum power density of 45mW/m2). More extensive tests with a single-chambered air cathode MFC produced a maximum power density with the animal wastewater of 261mW/m2 (200O resistor), which was 79% larger than that previously obtained with the same system using domestic wastewater (14678mW/m2) due to the higher concentration of organic matter in the swine wastewater. Power generation as a function of substrate concentration was modeled according to
saturation kinetics, with a maximum power density of Pmax ¼ 225mW=m2 (fixed 1000O resistor) and half-saturation concentration of Ks ¼ 1512mg=L (total COD). Ammonia was removed from 19871 to 3471 mg/L (83% removal). In order to try to increase power output and overall treatment efficiency, diluted (1:10) wastewater was sonicated and autoclaved. This pretreated wastewater generated 16% more power after treatment (11074mW/m2) than before treatment (9674mW/m2). SCOD removal was increased from 88% to 92% by stirring diluted wastewater, although power output slightly decreased. These results demonstrate that animal wastewaters such as this swine wastewater can be used for power generation in MFCs while at the same time achieving wastewater treatment.