Biomethanation of syngas at high CO concentration in a continuous mode

Syngas from pyrolysis/gasification process is a mixture of CO, CO₂ and H₂, which could be converted to CH₄, so called syngas biomethanation. Its development is obstructed due to the low productivity and CO inhibition. The aim of this study was to demonstrate the feasibility of using syngas as the only carbon source containing high CO concentration (40%) for biomethanation. Lab-scale thermophilic bioreactor inoculated with anaerobic sludge was operated continuously for over 900 h and the shift of microbial structure were investigated. Results showed that thermophilic condition was suitable for syngas biomethanation and the microbes could adapt to high CO concentration. Higher processing capacity of 12.6 m³/m³/d was found and volumetric methane yield of 2.97 m³/m³/d was observed. These findings could strengthen the theoretical basis of syngas biomethanation and support its industrialization in the future.