Anode Modification with FeO Affects the Anode Microbiome and Improves Energy Generation in Microbial Fuel Cells Powered by Wastewater.

This study investigated how anode electrode modification with iron affects the microbiome and electricity generation of microbial fuel cells (MFCs) fed with municipal wastewater. Doses of 0.0 (control), 0.05, 0.1, 0.2, and 0.4 g FeO per the total anode electrode area were tested. FeO doses from 0.05 to 0.2 g improved electricity generation; with a dose of 0.10 g FeO, the cell power was highest (1.39 mW/m), and the internal resistance was lowest (184.9 Ω). Although acetate was the main source of organics in the municipal wastewater, propionic and valeric acids predominated in the outflows from all MFCs. In addition, Fe-modification stimulated the growth of the extracellular polymer producers sp. and sp., which favored biofilm formation. Electrogenic sp. had the highest percent abundance in the anode of the control MFC, which generated the least electricity. However, with 0.05 and 0.10 g FeO doses, sp., sp., and sp. predominated in the anode microbiomes, and with 0.2 and 0.4 g doses, the electrogens sp. and sp. predominated. This is the first study to holistically examine how different amounts of Fe on the anode affect electricity generation, the microbiome, and metabolic products in the outflow of MFCs fed with synthetic municipal wastewater.