PROCEDE DE TRAITEMENT D'UN EFFLUENT LIQUIDE COMPRENANT UNE METHANISATION, UN TRAITEMENT BIOLOGIQUE, UNE DIGESTION DE BOUES METHANISEES ET DE BOUES BIOLOGIQUES, ET UNE METHANISATION DE BOUES DIGEREES

The invention relates to a process for treating liquid effluent, said process comprising a step of methane fermentation of said effluent within a methane fermenter (32) producing biogas, methane-fermented sludges and a methane-fermented effluent, a step of biological treatment of said methane-fermented effluent within a biological treatment zone (34) producing biological sludges and a treated effluent, a step of extraction of thickened biological sludges from said biological treatment zone (34), a step of anaerobic digestion of at least one portion of said methane-fermented sludges and of said thickened biological sludges within a digestor (44) producing biogas and digested sludges, a step of recirculating at least one portion of said digested sludges to said methane fermenter (21), and a step of extracting at least one portion of the digested sludges.