A large cathode surface area promotes electromethanogenesis at a proper external voltage in a single coaxial microbial electrolysis cell

Abstract

Microbial electrolysis cell coupled with anaerobic digestion (MEC-AD) is currently encountering constraints on electromethanogenesis. The electrode configuration modification can be a simple yet efficient way to improve electromethanogenesis. This study evaluated two coaxial electrode configurations (large anode and small cathode: A10C1; small anode and large cathode: A1C10) using carbon felt as the electrode material. At an external voltage of 1.7 V, CH4 content was found exclusively higher in A1C10 (11 % and 13 % higher for acetate-fed and cow manure-fed, respectively) than that of the control reactors. Consequently, CH4 production was 13 % and 29 % higher in acetate-fed and CM-fed A1C10, respectively. The strengthened electromethanogenesis was attributed to the enrichment of interspecies hydrogen transfer microbes (i.e., Mesotoga and Bathyarchaeia). The coaxial configuration with a large cathode surface area demonstrated a viable stereotype in MEC-AD for improved waste treatment and energy recovery.