Biomethane production from cheese whey in a two-phase anaerobic digestion system: integration of sewage sludge treatment and dairy byproducts recovery

Efficient anaerobic digestion does not only represent a suitable solution for sludge disposal, but also provides additional energy gain from biogas use in cogeneration. Co-digestion of sewage sludge with additional compounds can be beneficial for the whole process because of the synergic interactions between substrates. Furthermore, the integration of different types of local resources often results in significant cost savings, e.g. transport costs. Following an agreement between two major Italian companies, Hera Spa (a leading multiutility in waste business) and the Granarolo Group (one of the most important Italian dairy industries), cheese whey was introduced as substrate in the TPAD system. The overall performance was interesting under both production and environmental standpoints, and whey can be introduced in a CO2-boosted TPAD system to improve methane production rate.