Effect of start-up strategies and electrode materials on carbon dioxide reduction on bio-cathodes.

In this study, pre-enrichment of acetate-oxidizing bio-anodes did not facilitate start-up of bio-cathodes. It took about 170 days for the pre-enriched electrodes to generate substantial cathodic current compared to 83 days for the bare electrodes. Graphite foil and carbon felt cathodes produced higher current at the beginning of the experiment compared to graphite rods. However, all electrodes produced similar current densities at the end of the over 1-year long study (2.5 A/m2). Methane was the only product during operation of the bio-cathodes. Acetate was the only product detected after inhibition of the methanogens. Microbial community analysis showed that Geobacter sp. dominated the bio-anodes. On the bio-cathodes, the Geobacter sp was succeeded by Methanobacterium sp. which made up more than 80% of the population. After inhibition of the methanogens, Acetobacterium sp became dominant on the electrodes (40% relative abundance). The results suggested that bioelectrochemically generated H2 acted as an electron donor for CO2 reduction.Importance In microbial electrochemical systems, living microorganisms function as catalysts for reactions on the anode and/or the cathode. There is a variety of potential applications ranging from wastewater treatment and biogas generation to production of chemicals. Systems with bio-cathodes could be used to reduce CO2 to methane, acetate, or other high-value chemicals. The technique can be used to convert solar energy to chemicals. However, ...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research