Performance of a batch two-chambered microbial fuel cell operated at different anode potentials

BACKGROUND: For a microbial fuel cell (MFC), the anode potential is an important electrochemical parameter for the growth, electron distribution and electrical activity of exoelectrogenic bacteria. RESULTS: The performance of a batch-flow two-chambered MFC was investigated operated at anode potentials of - 400, - 200, 0, + 200 and + 400 mV versus Ag/AgCl reference electrode. Glucose was used as substrate and ferricyanide as cathodic electron acceptor. At potentials from - 400 to + 200 mV, increasing maximum current outputs were obtained, ranging from 6.0 to 8.6 mA. However, the maximum current output decreased to 6.9 mA when the anode potential was further increased to + 400 mV. More positive potentials resulted in higher Coulombic efficiencies (CEs), with values increased from 64% (-400 mV) to 88% (+400 mV). Electrons deposited as H₂ and CH₄ resulted in lower CEs at more negative potentials (-400, - 200 and 0 mV). When + 400 mV was applied to the anode, the growth yield dropped from 0.25 ± 0.05 to 0.11 mol biomass mol^-1 COD (chemical oxygen demand) with inhibition of electrical activity. CONCLUSIONS: The most positive anode potential reduced growth yield and inhibited bacterial growth, but electrical activity increased for potentials ranged from - 400 to + 200 mV. When the potential was increased to + 400 mV, growth yield was limited, affecting MFC performance.