Syngas biomethanation in countercurrent flow trickle-bed reactor operated under different temperature conditions

Syngas, a mixture of CO, H2, and CO2, is produced by waste carbonaceous feedstocks gasification, which plays an important role in renewable energy production. This study investigated the biomethanation of syngas (45% H2, 30% CO, 25% CO2) in a trickle-bed reactor operated under mesophilic (35 degrees C), hyper-mesophilic (45 degrees C), and thermophilic conditions (55 degrees C). The results revealed that CH4 production increased with increasing tempera-ture. CH4 production under steady-state conditions at the hyper-mesophilic and thermophilic temperatures were comparable; 92.2 +/- 1.7 mmol/(Lbed center dot d) and 93.9 +/- 0.9 mmol/(Lbed center dot d), respectively. On the contrary, electron losses in volatile fatty acids were the highest under mesophilic conditions. Additionally, digestate can be dosed as a nutrient addition and as a continuous inoculum source to ensure the optimal syngas biomethanation perfor-mance. The hyper-mesophilic conditions strategy illustrates possible energy savings for bioreactor heating with CH4 production comparable to thermophilic conditions, thus saving operating costs.

Automated summary

This study investigated the effect of different temperatures on the biomethanation of Syngas and found that CH4 production increased with increasing temperature. The CH4 production under hyper-mesophilic conditions was comparable to thermophilic conditions, resulting in potential energy savings and reduced operating costs.