(89g) Understanding Long-Term Changes in Microbial Fuel Cell Internal Resistances Using Electrochemical Impedance Spectroscopy

Microbial fuel cells (MFCs) exhibit a promising synergy between wastewater treatment and power production. Exoelectrogenic bacteria simultaneously produce an electric current, while degrading carbon compounds in wastewater. The performance of MFCs is controlled via internal resistance mechanisms that limit reaction rates and material transport. Electrochemical impedance spectroscopy (EIS) was used to study how these internal resistances changed over time. The biocatalyst was enriched in a compact, flow-through, porous anode chamber; the passive air cathode was separated from the bioanode with a Nafion polymer electrolyte membrane (PEM). The anode charge-transfer resistance was observed to decrease during the establishment of the microbial consortium in the anode. The solution resistance, which included the PEM, was observed to stay relatively stable throughout the experimental period, while the cathode resistance increased slightly. This study integrates power density and EIS studies to provide a better understanding of how an MFC changes over time and also to provide insight into operational parameters that facilitate long-term, high-power density operation of MFCs.