Effect of start-up strategies and electrode materials on carbon dioxide reduction on biocathodes
Journal article, 2018

The enrichment of CO 2 -reducing microbial biocathodes is challenging. Previous research has shown that a promising approach could be to first enrich bioanodes and then lower the potential so the electrodes are converted into biocathodes. However, the effect of such a transition on the microbial community on the electrode has not been studied. The goal of this study was thus to compare the start-up of biocathodes from preenriched anodes with direct start-up from bare electrodes and to investigate changes in microbial community composition. The effect of three electrode materials on the long-term performance of the biocathodes was also investigated. In this study, preenrichment of acetate-oxidizing bioanodes did not facilitate the start-up of biocathodes. It took about 170 days for the preenriched 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 than did graphite rods. However, all electrodes produced similar current densities at the end of the over 1-year-long study (2.5 A/m 2 ). Methane was the only product detected during operation of the biocathodes. Acetate was the only product detected after inhibition of the methanogens. Microbial community analysis showed that Geobacter sp. dominated the bioanodes. On the biocathodes, the Geobacter sp. was succeeded by Methanobacterium spp., 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 H 2 acted as an electron donor for CO 2 reduction.

Microbial electrolysis cells

Methanogens

Microbial community structure

Biocathode

Cyclic voltammetry

Acetogens

Start-up strategies

Author

Soroush Saheb Alam

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Abhijeet Singh

Swedish University of Agricultural Sciences (SLU)

Malte Hermansson

University of Gothenburg

Frank Persson

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Anna Schnürer

Swedish University of Agricultural Sciences (SLU)

Britt-Marie Wilen

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Oskar Modin

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Applied and Environmental Microbiology

0099-2240 (ISSN) 1098-5336 (eISSN)

Vol. 84 4 e02242-17

Subject Categories

Analytical Chemistry

Other Chemical Engineering

Microbiology

DOI

10.1128/AEM.02242-17

More information

Latest update

4/11/2018