(188cz) Bioelectrochemical Reduction of Carbon Dioxide to Methane and Acetate Using Thermophilic Microorganisms

The bioelectrochemical reduction of carbon dioxide (CO₂) offers new possibilities of energy storage and value-added chemicals production using electrode-microorganisms interaction. The bioelectrochemical conversion of CO₂ using thermophilic microorganisms occurred with higher conversion rates than using mesophilic microorganisms. Bioelectrochemical reactor with single-chamber type inoculated with thermophilic sludge was operated at 60 ^oC and a poised potential of -0.65 V vs SHE, using only CO₂ as a feedstock. Bioelectrochemical methane (CH₄) production was detected with 7.4 L CH₄/m²/d. Microbiome analysis showed Methanothermobacte wolfeii was dominated in the reactor. At about 100 days, the current increase was observed, and acetate was also produced as 10.5 g/L, as well as methane production. Microbial community analysis suggested one possibility of bioelectrochemical production of acetate by sulfate-reducing bacteria such as Desulfotomaculum peckii. This study showed one practical conversion route of electrical energy to biofuels (methane) and chemicals (acetate) from CO₂.