Electricity production and sludge reduction by integrating microbial fuel cells in anoxic-oxic process

To produce energy and reduce sludge production from the treatment of municipal wastewater, four identical microbial fuel cells (MFCs) were constructed in an anoxic-oxic (A/O) process (MFCs-A/O system). Experimental results indicated that this system enhance the removals of chemical oxygen demand (COD) and total nitrogen (TN). The electricity produced by each MFC were ranged from 0.371 to 0.477 V (voltage) and from 138 to 227 mW/m3 (power density) at the stable stage, when the external resistance was fixed at 1000 Ω. The coulombic efficiency of the MFCs-A/O system ranged from 0.31% to 1.68% (mean = 0.72%) at the stable stage, respectively. The removals of COD and TN in the MFCs-A/O system were slightly higher than those in the control system. Compared with the control system, the MFCs-A/O system can reduce waste activated sludge production and sludge yield by 24.0% and 24.2%, respectively. The experimental results indicated that the MFC constructed in A/O system improves wastewater treatment and the MFCs-A/O system can produce electricity while reducing sludge production and increasing wastewater treatment efficiency.