Optimization of hydrogen and methane production in two-phase Anaerobic digestion

Bio2Energy project aims at improving the efficiency of public utility facilities such as wastewater treatment plants and increasing the production of renewable energy in Tuscany. The production of biohydrogen and biomethane from the co-digestion of Organic Fraction of Municipal Solid Waste (Food Waste, FW) and sewage waste sludge (WS) and the use of digestate as agricultural fertilizer are the main objectives that position the project within the Circular Economy Strategy. Anaerobic digestion is a proven technology for the production of renewable energy but this technology is even more interesting if it is exploited also for hydrogen production. Therefore, the production of biohydrogen occurring in the acidogenic phase could be associated with anaerobic digestion (AD) so as to generate two gas streams (H2 and CH4), useful for different stakeholders, separately or mixed together. Our results revealed that the anaerobic co-digestion of sludge and food waste is an effective process able to produce energy self-sufficiency of wastewater treatment plants. Two-phase anaerobic digestion tests demonstrate the possibility to assess the production of hydrogen and methane in specific cases (sludge and food waste) and estimate the primary energy produced by different biogas users.