A combined system of microbial fuel cell and intermittently aerated biological filter for energy self-sufficient wastewater treatment

Energy self-sufficiency is a highly desirable goal of sustainable wastewater treatment. Herein, a combined system of a microbial fuel cell and an intermittently aerated biological filter (MFC-IABF) was designed and operated in an energy self-sufficient manner. The system was fed with synthetic wastewater (COD = 1000 mg L −1 ) in continuous mode for more than 3 months at room temperature (~25 °C). Voltage output was increased to 5 ± 0.4 V using a capacitor-based circuit. The MFC produced electricity to power the pumping and aeration systems in IABF, concomitantly removing COD. The IABF operating under an intermittent aeration mode (aeration rate 1000 ± 80 mL h −1 ) removed the residual nutrients and improved the water quality at HRT = 7.2 h. This two-stage combined system obtained 93.9% SCOD removal and 91.7% TCOD removal (effluent SCOD = 61 mg L −1 , TCOD = 82.8 mg L −1 ). Energy analysis indicated that the MFC unit produced sufficient energy (0.27 kWh m −3 ) to support the pumping system (0.014 kWh m −3 ) and aeration system (0.22 kWh m −3 ). These results demonstrated that the combined MFC-IABF system could be operated in an energy self-sufficient manner, resulting to high-quality effluent.