Evaluation of ex-situ hydrogen biomethanation at mesophilic and thermophilic temperatures

The biogas is seen as a key renewable resource in achieving the targets of countries renewable energy strategies. However, due to the high amount of CO2 concentration in biogas production, the energy level of biogas decreases, and the use of biogas as an alternative energy source is limited. The hydrogenotrophic methanogenesis process is one of the key technology that capable to convert CO2 to CH4 with H2 biomethanation. In this study the ex-situ hydrogenotrophic methanogenesis under mesophilic and thermophilic conditions and kinetic parameters such as H2 utilization rates, CH4 yields and H2 gas-liquid mass transfer rates were evaluated. The highest CH4 concentrations were obtained as of 79 and 81% from the mesophilic and thermophilic reactors at H2:CO2 ratio of 4:1. Also, the efficiency of hydrogen utilization (hH2) increased to 92% and the CH4 yield (YCH4) reached to 0.28 LCH4/LH2 in thermophilic reactors.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.