NOVELTY - The plant has an external solid waste stoking hopper (1) from which waste passes to a spiral conveyor (2) which carries it to a closed upper stoking hopper (3) where the waste passes through an electric valve controlling the flow of material (7) to a lower hopper (4). The lower hopper has an electric valve (21) to control the gas connected to a secondary vacuum pump (23), and an alveolar control valve (8) connected to a continuous tubular catalytic cracking reactor.    USE - As a solid waste treatment plant for treating waste pyrolytically, e.g. the combustible fraction of rejected solid urban waste, rubber, tires, leather, textiles, complex plastic materials, wood and forestal biomass, oils and liquid emulsions and infectious, toxic and hazardous waste.    ADVANTAGE - The energetic performance, speed of treatment and control of the reaction products are improved, based on a controlled pyrolytic process under depression conditions at low temperatures.    DETAILED DESCRIPTION - The solid waste treatment plant uses a pyrolytic process in which the vacuum conditions are maintained throughout the entire system. The plant comprises an external, continuous solid waste stoking hopper (1), with waste coming out to a spiral conveyor (2) which carries it a closed upper stoking hopper (3) where the waste passes through an electric valve which controls the flow of material (7) from the upper hopper to a lower hopper (4). The lower hopper has an electric valve (21) to control the gas connected to a secondary vacuum pump (23), and an alveolar control valve (8) which is connected to a continuous tubular catalytic cracking reactor comprising two interconnected reaction pipes, an upper pipe (10) and a lower pipe (11), both with spiral conveyors (25) and variable speed motors (13,14). The reactor is a complete head type with direct heating with lid-resistances (12) positioned on the top.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the solid waste treatment plant.    External, continuous solid waste stoking hopper (1)    Spiral conveyor (2)    Upper stoking hopper (3)    Lower stoking hopper (4)    Material flow (7)    Alveolar control valve (8)    Upper and lower pipes (10,11)    Lid resistances (12)    Variable speed motors (13,14)    Electric valve (21)    Secondary vacuum pump (23)    Spiral conveyors (25)