NOVELTY - The waste matter (H) is decomposed into heat decomposition gas (S) and carbide (T). The heat decomposition gas is dechlorinated to form dechlorinated gas (D) which is used as a heat source for a waste heat recovery boiler (8). Combustible gas (F) generated for driving a gas turbine (4) is also used by the waste heat recovery boiler for generating steam for driving a steam turbine (9).    USE - For processing city refuse e.g. paper or waste plastics or biomass industrial waste, e.g. straw, timber chips and waste pulp.    ADVANTAGE - As throughput of waste matter per unit time is increased, energy utilization efficiency of the refuse is improved. Since the heat decomposition gas is made into a heat source for the waste heat recovery boiler, the cost for heating the waste heat recovery boiler is reduced, and the waste matter is cheaply processed. Since chlorine is removed from the heat decomposition gas, at least part of the chlorine is removed from waste matter. Since chlorine is removed from the heat decomposition gas, corrosion of the thermal decomposition furnace is prevented. The system is simplified which reduces the cost.    DETAILED DESCRIPTION - Combustible gas is generated by a coal gasification installation (1) for driving a gas turbine which is used by a waste heat boiler for generating steam. The waste matter (H) is decomposed in the thermal decomposition furnace (14) into carbide (T) and heat decomposition gas (S). The carbide (T) is blended with coal (C) while passing through a main conveying path (16). A portion of chlorine is removed from the heat decomposition gas by a chlorine removal apparatus (19) and the dechlorinated heat decomposition gas (D) is made as a heat source of the waste heat recovery boiler by a heat source apparatus (22).    An INDEPENDENT CLAIM is also included for a waste disposal system.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of the waste matter processing apparatus.    Coal gasification installation (1)    Turbines (4,9)    Boiler (8)    Furnace (14)    Chlorine removal apparatus (19)    Heat source apparatus (22)    Coal (C)    Heat decomposition gas (D,S)    Combustible gas (F)    Waste matter (H)    Carbide (T)