Influence of nutrient medium supply rate and liquid recirculation regime on syngas biomethanation in thermophilic trickle-bed reactor

Abstract

Syngas biomethanation enables the use of recalcitrant biomass or waste for methane production. To reveal knowledge on the importance of nutrient medium supply rate (NMSR) and liquid recirculation regime, a thermophilic 5 L trickle-bed reactor was operated for 283 days. Efficient and stable operation with >99 % H-2 and CO conversion rates was achieved at a minimum NMSR of 14 mL/(L-pbvd) and 1 h gas retention time, yielding a maximum methane evolution rate (MER) of 4.3 L/(L-pbvd). Reduced intermittent liquid recirculation resulted in lowered MERs (max. 3.4 L/(L-pbvd)) with CO conversion more affected by low recirculation frequencies than H-2 conversion. The microbial analysis revealed a similar microbial community structure across all experimental phases, dominated by Methanothermobacter in both liquid and carrier biofilm. CO was likely converted to methane and acetate, with syntrophic acetate-oxidizing bacteria metabolizing acetate to H-2 and CO2, supporting efficient hydrogenotrophic methanogenesis.

Keywords

Biosyngas; Digestate; Hydraulic retention time; Trickling; Syntrophic acetate oxidation; Methanothermobacter

Published in

Bioresource technology reports
2025, volume: 32, article number: 102353
Publisher: ELSEVIER

SLU Authors

• Gabler, Florian

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • RISE Research Institutes of Sweden

• Cheng, George

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Schnürer, Anna

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Nordberg, Åke

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Bioenergy

Publication identifier

• DOI: https://doi.org/10.1016/j.biteb.2025.102353

Permanent link to this page (URI)

https://res.slu.se/id/publ/144562