Process for treating solid waste containing an organic fraction, comprising an initial step of extrusion pressing the waste with production of a solid fraction and a liquor. The solid fraction is subjected to a milling treatment at a pressure lower than the atmospheric pressure in a rotary mill that produces a sanitized dry solid and water. The liquor is subjected to a treatment of anaerobic digestion in three subsequent steps, with production of biogas and of a digestate that is subjected to evaporation under vacuum to obtain a concentrated compost and steam, re-used in other steps of the process. The sanitized dry solid and the biogas can be used as fuel to produce thermal and electric energy to be used in the process, which also allows surplus energy to be obtained.
