Co-fermentation of sewage sludge and CO2 boosted by alcohol-containing bioliquids: enhancing biomethane production in a two-phase anaerobic digestion process.

Two-phase anaerobic digestion (TPAD) is an efficient technology for energy recovery from biomass and wastes, and represents an interesting contribution to address fossil fuels substitution. The use of CO2 to improve solid degradation and methane production in the anaerobic digestion has been described for sewage sludge, as a result of a long-term R&D activity. The work is now focused on valorization of synergic effects of CO2 and biomasses, such as alcohol-containing bioliquids. Different combination of Ethanol and Methanol where tested. The best results were obtained with 100% Ethanol, but Methanol is also an efficient booster of acidogenic/acetogenic metabolism.