A novel two-stage process for biological conversion of syngas to biomethane.

This study shows biomethane production in a novel two-stage syngas biomethanation consisting of the thermophilic anaerobic digestion of sewage sludge combined with an injection of syngas as the first stage. Since the syngas does not contain enough reducing equivalents, the produced biogas was connected to the second stage consisting of the trickle-bed reactor with the external H addition (ex-situ) to increase the CH content further. The aim was to evaluate the influence of different syngas compositions on the biomethane production in both stages.