Abstract: A plant for the treatment of biological sludges with recovery of secondary raw materials and energy including, in a system architecture, a feed section (1) of biological sludges and a feed section (2) of primary and secondary raw materials required for operation of the plant, characterized in that it includes a section (3) for the treatment of biological sludges wherein, through a reactor (303), a process of alkaline protein lysis is performed at medium-low temperature, through dosage of a calcium or sodium hydroxide, obtaining a suspension including a protein broth and a suspended body composed of the calcium or sodium hydroxide, of the non-solubilized organic fraction and of the particulate of the hydroxides of the polluting metals contained in the sludges and wherein, through a forced filtration device (304) of the suspension, separation of the liquid protein lysate from the cake of suspended particulate is obtained.