Effect of Organic Concentration in the Anode and Cathode on Bioelectricity Generation and Denitrification in a Single-Cathode Three-Anode Microbial Fuel Cell

Abstract

An innovative single-cathode three-anode microbial fuel cell (SCTA-MFC) was constructed, using sodium acetate as the anode organic substrate and nitrate as the cathode electron acceptor. It was found that in the case of a closed circuit with chemical oxygen demand (COD) in the cathode, higher maximum power density (PDM, 642.51 mW·m−3), COD, and nitrate removal efficiency (85.70%, 64.35%) could be obtained. The influence of initial organic concentration of the anode was investigated. When the concentration was about 600 mg·L−1, removal efficiency of COD was 87.20%, maximum coulombic efficiency (CEM) in the anode was 3.42%, PDM was 795.70 mW·m−3, and the nitrate removal efficiency and the CEM in the cathode were 75.52% and 99.50%, respectively. The presence of cathode organics can couple autotrophic and heterotrophic denitrification of SCTA-MFCs, and further enhance denitrification rates. An anode organic concentration of 600 mg·L−1 is beneficial to electricity generation of SCTA-MFCs.