Small-scale anaerobic digester technology in water methanisation still needs to be optimised to make it technically and economically feasible. Little experience has thus been developed in recent years in Wallonia with regard to small units. To meet demand, it is important to adapt and further develop anaerobic technologies that are already proven on a large scale or at the conceptual stage. The purpose of the project is to develop a biomethanizer for liquid effluents from SMEs in the agri-food sector, characterized by high concentrations and small volumes. The research focuses on the development of the process and its adaptation to the SME context (hydraulics, energy recovery from the biogas produced, simplicity of operation and robustness) as well as on the development of an efficient bacterial support. While SMEs are the end users, the primary beneficiaries of the technology developed are companies in the water treatment sector, active in the capacities of the treatment plants concerned.