Phasic availability of terminal electron acceptor on oxygen reduction reaction in microbial fuel cell

•Phase of availability of TEA has influenced ORR kinetics.•High performance of MFC-DC (PD-769 mW/m2) than MFC-SC (PD-684 mW/m2).•Rapid neutralization of redox equivalents with DO as TEA.•Benefit of higher bioelectricity generation along with wastewater treatment.

Oxygen-reduction reactions (ORR) plays a pivotal role in determining microbial fuel cells (MFC) performance. In this study, an attempt to determine the influence of the phasic availability of terminal electron acceptor (TEA) on ORR was made. Two MFCs operated with dissolved oxygen (MFC-DC) and air (MFC-SC) as TEA were constructed and analyzed in continuous mode under open and closed circuit conditions. The bio-electrochemical analysis showed a marked influence of dissolved oxygen resulting in a maximum power density with MFC-DC (769 mW/m2) compared to MFC-SC (684 mW/m2). The availability of O2 in dissolved phase has lowered the activation losses during the MFC operation as a result of effective ORR. The cyclic voltammetry analysis revealed the TEA dependent biocatalyst activity of NADH and cytochrome complex which enabled electron transfer kinetics and improved substrate utilization. Finally, the study evidenced the critical role of TEA phasic availability to regulate the bio-electrogenic and substrate degradation potential in MFC.