Comparative evaluation of digestate and reject water as nutrient media for syngas biomethanation in thermophilic trickle-bed reactors

Abstract

Syngas biomethanation facilitates the utilization of thermal gasification products. This study evaluated the performance of two liquid organic waste streams (manure-based digestate and reject water from digested sewage sludge) as nutrient media in thermophilic trickle-bed reactors (TBRs) over more than one year. Digestate achieved a Methane Evolution Rate (MER) of 4.5 L/(L-pbvd) with the highest so far published H-2 and CO conversion rates (>95 %). Reject water only led to a maximum MER of 1.0 L/(L-pbvd), while the addition of sulfur and phosphorus to the reject water resulted in improved MER of up to 3.1 L/(L-pbvd). The microbial analysis illustrated a similar microbial community structure and methanogenic abundance for both TBRs, with Methanothermobacter as the dominating methanogen both in the liquid phase and biofilm of the carriers. Carbon monoxide was likely converted to both methane and acetate.

Keywords

Biosyngas; Hydrogen; Carbon Monoxide; Sulfur; Microbial Community; Phosphorus

Published in

Bioresource Technology
2025, volume: 435, article number: 132893
Publisher: ELSEVIER SCI LTD

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.biortech.2025.132893

Permanent link to this page (URI)

https://res.slu.se/id/publ/143032