Syngas biomethanation: effect of biomass-gas ratio, syngas composition and pH buffer

The concept of syngas biomethanation is attractive, however, it still needs improvement in optimizing the operational conditions. In the present study, syngas fermentations under different carbon monoxide (CO), carbon dioxide (CO2) and hydrogen (H-2) compositions were conducted under two different biomass-gas ratio (BGR) systems. The results showed that high BGR enhanced the CO consumption rate, achieving a 60% enhancement with CO as the sole substrate. Stoichiometric H-2 addition could successfully convert all the CO and CO2 to pure methane, however, higher H-2 partial pressure might decline the CO consumption due to pH inhibition from consumption of bicarbonate. Microbial analysis showed different syngas composition could affect the bacteria community, while, archaea community was only slightly affected with Methanothermobacter as the dominant methanogen. This study provided strategy for efficient syngas biomethanation and deeper insight into effect of H-2 addition on CO conversion under different BGR systems.

Automated summary

The study found that high BGR can enhance the consumption rate of CO, while stoichiometric H-2 addition can convert CO and CO2 to pure methane. Microbial analysis showed that the composition of syngas can affect the bacteria community, but has minimal impact on the archaea community.