Metagenomic on long-term ex-situ biological methanation of hydrogen and carbon dioxide

The present work represents a study focused on a gas transfer system based on controlled hydrodynamic cavitation coupled to an ex-situ hydrogenotrophic biomethanation process. The hydrodynamic cavitation system was coupled to a tubular biological reactor in order to supply the methanogenic archaea with exogenous H2 and CO2 in thermophilic conditions. The experimental trials showed a positive effect of controlled cavitation on methanogenic process, reaching a volumetric methane production rate of 1.9 m3 CH4/m3rd by adopting a H2 loading rate of about 10 m3/m3rd without any gas recirculation from the headspace of the reactor. The experimentation lasted about 160 days and at the end of the operation the archaeal community was dominated by hydrogenotrophic methanogenic archaea.