The aim of the presented study is to investigate a new energy saving concept in the integrated sewage sludge and organic fraction of solid waste (OFMSW) treatment thanks to pre-treatment options of OFMSW and innovative biological treatment of anaerobic digester liquid. An energy – saving wastewater treatment can be obtained by maximizing the energy production from organic compounds through anaerobic co-digestion and minimizing energy consumption for nitrogen removal not only in the main stream of wastewater treatment plants (WWTPs) but also in the secondary streams such as anaerobic digestion effluents. The configuration proposed consists in a mechanical pre-treatment of the OFMSW with the washing of the waste, thermochemical pre-tratment with 500 mgNaOH/kgOFMSW at 40°C for 30 min and the centrifugation process, followed by a codigestion of sewage sludge and OFMSW and by a post-treatment of liquid fraction produced in a dewatering stage after the anaerobic one with an innovative biological process, SNAD - like.