Accelerated start-up and improved performance of wastewater microbial fuel cells in four circuit modes: Role of anodic potential

Wastewater microbial fuel cells (MFCs) can transform the chemical energy into electricity; however, little is known on the effect of circuit modes on start-up and performance of wastewater MFCs. Here we have investigated the effect of four circuit modes on start-up, performance and membrane fouling of MFCs systematically. Besides shortening the start-up period and improving the performance of MFCs, applying anodic negative potential also balances pH of the system and thus enhances COD removal. The open-circuit constant potential mode (OC-MFC) presents the shortest start-up period of 5 days, with the highest voltage output of 810 mV and the slightest membrane fouling, which provides an effectively strategy to accelerate the start-up of wastewater MFCs. The circuit mode applied to start up wastewater MFC not only affects the degree of membrane fouling, but also causes significant differences in anode microbial communities. The total abundance of exoelectrogens in the closed-circuit intermittent potential (CI-MFC) mode was the highest up to 54.70%, but the performance of CI-MFC inferiors to OC-MFC, indicating that performance of the wastewater MFC is not solely determined by the dominant bacteria. Overall, the OC-MFC provides a new strategy to accelerate the start-up period and enhance performance of wastewater MFC simultaneously.