NOVELTY - Multistep procedure for processing mechanically reprocessed waste containing organic materials in a processing device (I) and (III) under addition of water, continuous treatment with mechanical circulation of water and separation of predominant solid waste part and predominant liquid waste part, comprises treating the waste between the processing device (I) and (III) for the separation into predominant solid waste part in processing device (III) and predominant liquid waste part in processing device (II).    USE - The process is useful for the production of high quality substitute fuels from the waste.    ADVANTAGE - The process is carried out with short retention time and with maximum yield of energy. The process mobilizes and reduces the fuel pollutants in the waste.    DETAILED DESCRIPTION - Multistep procedure for the processing mechanically reprocessed waste containing organic materials in a processing device (I) and (III) under addition of water and continuous treatment with mechanical circulation of water and separation of predominant solid waste part and predominant liquid waste part, comprises treating the waste between the processing device (I) and (III) for the separation into predominant solid waste part in the processing device (III) and predominant liquid waste part in processing device (II), where: for achieving an aerobic prefermentation of the waste, a retention time of the waste, preferably a supplementary processing of the waste in the bioprocessing device (II) and a specific parameter (P-II) of the waste are determined, where the parameter (P-II) of the waste comprises temperature, part of the organic substances in the waste, moisture of the waste and oxygen requirement of the waste; when there is a low temperature in the waste, the retention time of the waste is increased and/or mixing of the waste with the warmer waste fractions takes place; when there is a limited part of organic materials in the waste, the retention time of the waste gets lengthened and/or a mixing with organic rich waste fractions takes place; when there is low moisture in the waste then mixing the fractions with more moisture takes place and/or the waste gets moisturized; and the oxygen requirement of the waste is determined and optionally regulated. An INDEPENDENT CLAIM is included for a waste processing device (5) for processing waste containing organic materials, with a processing device (I) for the mechanical processing of waste and with a processing device (III) for further processing of the waste into a predominant solid waste part and a predominant liquid waste part, where between the processing device (I) and (III), a processing device (II) is arranged, in which the waste can be processed for prefermentation preferably for mixing, aerating and/or humidifying the waste.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of mechanical and biological waste treating device for processing the waste comprising organic materials.    Waste processing device (5)    Mixing container (7)    Dehydration device (9)    Water (13)    Pulp. (14)