Ex-situ single-culture biomethanation operated in trickle-bed configuration: Microbial H2 kinetics and stoichiometry for biogas conversion into renewable natural gas

• Published in: Bioresource technology Vol. 411; p. 131330
• Main Authors: Ale Enriquez, Fuad, Ahring, Birgitte K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2024
• Subjects: Biogas upgrading; Circular economy; CO2 capture; Gas fermentation; Hydrogenotrophic methanogenesis; Methanothermobacter; RNG; Methanothermobacter; Circular economy; Biogas upgrading; RNG; CO2 capture; Gas fermentation; Hydrogenotrophic methanogenesis
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131330

[Display omitted] •Single-culture biomethanation matches hydrogenotrophic methanogenesis stoichiometry.•Methanothermobacter wolfeii BSEL yields 99% CH4 in renewable natural gas.•Integrated Monod model was used to determine constants of microbial H2 uptake.•Biogas upgrading with M. wolfeii BSEL performs well with biogas mimic and real biogas. Biomethanation converts carbon dioxide (CO2) emissions into renewable natural gas (RNG) using mixed microbial cultures enriched with hydrogenotrophic archaea. This study examines the performance of a single methanogenic archaeon converting biogas with added hydrogen (H2) into methane (CH4) using a trickle-bed bioreactor with enhanced gas–liquid mass transport. The process in continuous operation followed the theoretical reaction of hydrogenotrophic methanogenesis (CO2 + 4 H2 → CH4 + 2 H2O), producing RNG with over 99 % CH4 and more than 0.9 H2 conversion efficiency. The Monod constants of H2 uptake were experimentally determined using kinetic modelling. Also, a dimensionless parameter was used to quantify the ratio between the H2 mass transfer rate and the maximum attainable H2 consumption rate. Single-culture biomethanation averts the formation of secondary metabolites and bicarbonate buffer interferences, resulting in lower demands for H2 than mixed-culture biomethanation.