Influence of operating pressure on the biological hydrogen methanation in trickle-bed reactors.

•Investigation of trickle-bed reactors for biological hydrogen methanation at different operating pressures.•Methane content increased by 34% with increasing pressure from 1.5 to 9bar (86vol-%).•Methane formation rates up to 4.28±0.26m3 CH4m−3d−1.