Development of Stable Mixed Microbiota for High Yield Power to Methane Conversion

Márk Szuhaj, Roland Wirth, Zoltán Bagi, Gergely Maróti, Gábor Rákhely and Kornél L. Kovács
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Márk Szuhaj: Department of Biotechnology, University of Szeged, 6726 Szeged, Hungary
Roland Wirth: Department of Biotechnology, University of Szeged, 6726 Szeged, Hungary
Zoltán Bagi: Department of Biotechnology, University of Szeged, 6726 Szeged, Hungary
Gergely Maróti: Institute of Plant Biology, Biological Research Centre, 6726 Szeged, Hungary
Gábor Rákhely: Department of Biotechnology, University of Szeged, 6726 Szeged, Hungary
Kornél L. Kovács: Department of Biotechnology, University of Szeged, 6726 Szeged, Hungary

Energies, 2021, vol. 14, issue 21, 1-17

Abstract: The performance of a mixed microbial community was tested in lab-scale power-to-methane reactors at 55 °C. The main aim was to uncover the responses of the community to starvation and stoichiometric H 2 /CO 2 supply as the sole substrate. Fed-batch reactors were inoculated with the fermentation effluent of a thermophilic biogas plant. Various volumes of pure H 2 /CO 2 gas mixtures were injected into the headspace daily and the process parameters were followed. Gas volumes and composition were measured by gas-chromatography, the headspace was replaced with N 2 prior to the daily H 2 /CO 2 injection. Total DNA samples, collected at the beginning and end (day 71), were analyzed by metagenome sequencing. Low levels of H 2 triggered immediate CH 4 evolution utilizing CO 2 /HCO 3 ? dissolved in the fermentation effluent. Biomethanation continued when H 2 /CO 2 was supplied. On the contrary, biomethane formation was inhibited at higher initial H 2 doses and concomitant acetate formation indicated homoacetogenesis. Biomethane production started upon daily delivery of stoichiometric H 2 /CO 2 . The fed-batch operational mode allowed high H 2 injection and consumption rates albeit intermittent operation conditions. Methane was enriched up to 95% CH 4 content and the H 2 consumption rate attained a remarkable 1000 mL·L ?1 ·d ?1 . The microbial community spontaneously selected the genus Methanothermobacter in the enriched cultures.

Keywords: power-to-gas; thermophilic biogas; fed-batch reactor; Methanothermobacter; metagenome; starvation; H 2 and CO 2 conversion; methane; acetate (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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