Characteristics and continuous operation of floating air-cathode microbial fuel cell (FA-MFC) for wastewater treatment and electricity generation

Microbial fuel cell with floating air-cathode is developed for not only wastewater treatment but also electricity generation from the wastewater. Graphite felt and carbon cloth coated with Pt of 5 gm−2 are used as anode and cathode electrodes in this system, respectively. When organic loading rate is 15.38 kgCODm−3day−1, maximum power density is 119.7 mWm−2 with about 60% of Coulombic efficiency. Electrode spacing between anode and cathode is one of the important factors for electricity generation. Power density increases from 60.35 mWm−2 to 121.68mWm−2 by reducing electrode spacing from 2.8 to 1.2 cm. This system has total internal resistance of 18.43 Ω, which is very low compared with other researches. Maximum power density of 628.8 mWm−2 is accomplished with Coulombic efficiency of 30.3% by continuous operation of four FA-MFC reactors that are connected by series. When COD concentrations of influent are 500 and 250 mgL−1, its removal rates are 63.3% and 83.7%, respectively.