The objective of the proposed BioGAIA project is to increase the biogas productivity in AD plants that normally treat mixtures of wastewaters based on their seasonal availability and thus operate for periods with mono-substrates, e.g. cheese whey in Italy or cow manure in Greece during summer, to co-digest other agroindustrial wastes or agro-residues available in the area in order not only to operate efficiently but at the maximum of their operational capacity throughout the year.Therefore, the BioGAIA project targets to increase the sustainability of such AD plants and convert them from waste treatment plants into biogas (bioenergy) production plants attractive for green entrepreneurs by efficiently combining the most appropriate agroindustrial wastes (of liquid or solid form) that are available in each partner area. The goal is dual in this cross-border joint action: protect the environment using AD while, at the same time, exploit the wastes’ energy content and the constructed plants in the most efficient and productive way in terms of energy (both electrical and thermal) and material production (digestate to be used as fertilizer).