Characterization of electricity generation and microbial community structure over long-term operation of a microbial fuel cell

In this study, a continuous-flow microbial fuel cell (MFC) system was constructed to treat azo dye wastewater for 400 days. The electrical properties of the MFC after 400-day operation and the removal efficiencies of the MFC after long- and short-term operation were analyzed with respect to co-substrate concentrations. The power output of the MFC system decreased from 586 to 330 mV with increasing operating time, and the removal efficiencies of the MFC remained stable after long-term operation in comparison to those after short-term operation, even when the co-substrate concentration was reduced. Analysis of the degradation products showed that products generated from long-term operation of the MFC were present at low concentrations. The microbial community analysis revealed that the relative abundance of microorganisms related to the degradation of organics in the MFC increased after long-term operation, and microorganisms related to electricity generation decreased.