Comparative Study of Electrochemical Performance and Microbial Flora in Microbial Fuel Cells by Using Three Kinds of Substrates

This work aimed to investigate the distinct electrochemical performance and microbial flora of microbial fuel cells(MFCs) in relation to different single hazardous fed fuels. Three replicate MFCs were inoculated with the same microbial consortium from a coking wastewater treatment plant, wherein ammonium chloride(ammonium chloride-fed MFC, N-MFC), phenol(phenol-fed MFC, P-MFC) and potassium sulphide(potassium sulphide-fed MFC, S-MFC) were the sole substrates and main components of real coking wastewater. With initial concentrations of ammonium chloride, phenol and potassium sulphide of 0.75, 0.60 and 0.55 g/L, the removal efficiencies reached 95.6%, 90.6% and 99.9%, respectively, whereas the peak output power densities totalled 697, 324 and 1215 mW/m². Microbial community analysis showed that the respective addition of substrate substantially altered the microbial community structure of anode biofilm, resulting in changes in relative abundance and emergence of new strains and further affecting the electrochemical properties of MFCs. The chemical oxygen demand(COD) removal efficiency of real coking wastewater, in which the inoculum was the combined biomass from the three MFCs, reached 82.3%.