Continuous CH4 Production from H2 and CO2 by Methanobacterium thermoautotrophicum in a fixed-bed reactor

Methanation of H₂ and CO₂ by Methanobacterium thermoautotrophicum ΔH was carried out in a fixed-bed reactor (31 mmφ × 180 mm H) packed with granular diatomaceous earth clay (2–3 mmφ) as a support material. The maximum methane production rate obtained was $\text{5.2}\text{l}\text{l}$ bed volume/h, while a conversion rate reaching up to some 80% of the theoretical value was achieved by controlling the feed rate of the substrate gas throughout the culture period. After cultivation methanogen cells were fixed almost homogeneously on the whole of the support material, giving 30 mg dry cell/cm³ packed support.