The Besòs Tordera Consortium deals with the treatment of wastewater from 64 municipalities of Vallès Oriental, a county in Catalonia, Spain. The consortium has 27 purifiers under management, but that of the capital, Granollers, has a special feature. For years, in this purifier, the resulting sludge from purification has been conveyed to a biogas plant to generate electrical and thermal energy. But not only: the Besòs Tordera Consortium, in partnership with the Gestión De Residuos Del Vallès Oriental Consortium, has also launched the BioVo project, to allocate part of the biogas generated by their plants to the production of biomethane and feed it into the Nedgia gas grid.