Treatment of sewage and synchronous electricity generation characteristics by microbial fuel cell

A microbial fuel cell (MFC) was built using glucose as simulated domestic wastewater, using carbon felt as anode and activated anaerobic sludge as inoculum, which came from a sewage treatment plant. The sewage was treated and electricity was generated synchronously. The effect of substrate concentration and operating temperature on electrode process kinetics was examined. The relationship among electrochemical activity of microbes, charge transfer resistance, anode potential, and capacity of producing electricity was explored. The main conclusions about sewage-fuel MFC are summarized as follows: The relationship between the peak power density and substrate concentration followed Monod enzyme kinetics equation: P=P_maxc/(k_s+c), with a maximum power density (P_max) of 320.2 mW/m² and half-saturation concentration (k_s) of 138.5 mg/L. When the initial glucose concentration is less than 2 000 mg/L, the reaction follows the first order kinetics equation: -dc_A/dt=kc_A, k=0.262 h^-1. Increasing the temperature from 20 to 35 ℃, the charge transfer resistance decreases from 361.2 to 36.2 Ω, the anode electrode potential also decreases, while peak power density increases from 80.6 to 183.3 mW/m². At 45 ℃, the electrochemical activity of microbes declines, and the peak power density decreases to 36.8 mW/m². After operating steadily for 6 h, coulombic efficiency and COD removal efficiency reach a maximum of 44.6% and 49.2%, respectively, at 35 ℃ with the substrate concentration of 1 500 mg/L.