Optimization of ex-situ biomethanation process in trickle bed reactor: The impact of slight H2/CO2 ratio adjustments and different packing materials

Abstract

This study aimed to evaluate and optimize trickle bed reactor (TBR) performance for biological biogas upgrading at different gas loading rates (10-35 m3/m3d) by adjusting H2 flow (H2/CO2 ratio 4-3.7) and utilizing various packing materials. The three TBR reactors operated at thermophilic conditions (50○C) with different packing materials under same gas loading rate. Obtained results indicated that optimal performance was achieved at a gas loading rate of 14.3 m3/m3d and H2/CO2 ratio of 3.7, with average CH4 concentrations in the effluent gas from 90.8 % to 91.5 %, regardless of the packing material employed. Increasing the gas loading rate resulted in decreased CH4 content (<90 %), indicating limited treatment capacity at higher loading rates. The studied packing materials had a slight impact on reactor performance indicating that the shape of the making material has a greater influence of the reactor performance. Microbial communities analyses revealed dominance of hydrogenotrophic methanogens (Methanobacterium, Methanothermobacter, and Methanoculleus). This study highlights the importance of optimizing the H2/CO2 and considering packing materials for TBR performance.