Methanothrix enhances biogas upgrading in microbial electrolysis cell via direct electron transfer

Bioresource Technology
Chuanqi LiuDawn E Holmes

Abstract

Bioelectrochemical conversion of CO2 to CH4 is a promising way to increase the calorific value of biogas produced during anaerobic digestion. There are two groups of methanogens enriched in these systems, hydrogenotrophs and acetoclastic methanogens that can also directly accept electrons from an electrode or another microorganism. In this study, a microbial electrolysis cell (MEC) poised at -500 mV (vs. SHE) was operated for biogas upgrading. Methane content in the biogas increased from 71% to >90%, and 8.2% of the CO2 was converted to methane. Methanothrix, an acetoclastic methanogen that can participate in direct electron transfer (DET), and Azonexus, an acetate-oxidizing electrogen, were enriched on the cathode. Transcriptomics revealed that Methanothrix on the cathode were using the CO2 reduction pathway, while Methanothrix in the bulk sludge were using the acetate decarboxylation pathway for production of methane. These results show that stimulation of DET in MEC enhances biogas-upgrading processes.

Citations

May 13, 2020·Brazilian Journal of Microbiology : [publication of the Brazilian Society for Microbiology]·Adriana GiongoRenata Medina-Silva
Apr 25, 2020·Water Environment Research : a Research Publication of the Water Environment Federation·Qi HuangBipro Ranjan Dhar
Sep 13, 2020·Trends in Biotechnology·Shanfei FuYifeng Zhang
Oct 9, 2020·Bioresource Technology·Fengbo WangMiaomiao Du

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