NOVELTY - Treatment of by-products based on organic materials, preferably animal-rearing co-products such as animal bedding, dung and liquid manure, and sludge discharged by wastewater purification plants, comprises a drying stage to produce a fuel that is subjected to gasification. The dried fuel is granulated in a stationary bed with inversed air draft and at atmospheric pressure prior to gasification    USE - Generation of electrical and thermal energy from animal-rearing co-products such as animal bedding, dung and liquid manure, and sludge discharged by wastewater purification plants.    ADVANTAGE - The invention provides a highly efficient installation of low capacity without presenting risks, especially in terms of environmental safety. The installation operates in an autonomous manner without requiring external energy sources and without having adverse effects on the environment, in particular with respect to the discharge of pollutants.    DETAILED DESCRIPTION - The gas discharged from the gasification stage is subjected to a cooling stage in a tubular heat exchanger, preferably with a falling film, cooled by a heat carrier fluid, and then to at least one scrubbing stage in absorption columns (7, 8). Heat carried by the heat carrier is recovered and used to heat the air used in the drying stage. The scrubbed gas is subjected to a filtration stage using a bed of sand or sawdust and/or a paper filter in parallel with treatment of the liquid effluents.    The scrubbed gas is passed to an internal combustion engine coupled to an electricity generator for the combined production of electricity and heat and/or to a burner for the production of heat. Heat discharged from the cooling water circuit of the engine unit and from the oil circuit, and/or obtained by channeling the engine exhaust gas to an aeraulic mixer, is recovered for heating the air used in the drying stage.    An INDEPENDENT CLAIM is given for an installation used to implement the invented process.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the different elements of the invented installation.    By-products (1)    Dryer (2)    Granulating press (3)    Fuel storage unit (4)    Gasifier (5)    Condenser (6)    Absorption columns (7, 8)    Filtration unit (9, 10)    Internal combustion engine (11)    Alternating electrical current generator (12)    Electrical supply network (13)    Hot air mixing unit (14)    Purifier (15)