NOVELTY - The method comprises subjecting a fermentation residue I (3) occurring from a biogas production plant with a fermenter (2) to a solid-liquid-separation, subjecting a liquid phase (6) of the fermentation residue I to a process for enlarging the solid surface and for removing dissolved gases, supplying the resulting product to the fermenter of the biogas production plant and/or to a further fermenter, where a fermentation residue II is resulted in the case of supplying the product to the further fermenter, and feeding the resulting fermentation residue II to a hydrolysis process step.    USE - Method for continuously treating biogenic materials for producing biogas, where the biogenic materials are renewable raw material, sewage sludge, agricultural wastewater, disposal wastewater, wastewater from waste treatment plants, biogenic residual or waste products from food industry and/or agriculture (claimed).    ADVANTAGE - The method ensures economical and efficient production of the biogas with high yield and high quality by increasing proportion of methane and reducing carbon dioxide and harmful hydrogen sulfide, and improves the efficiency of the fermentation process.    DETAILED DESCRIPTION - The method comprises subjecting a fermentation residue I (3) occurring from a biogas production plant with a fermenter (2) to a solid-liquid-separation, subjecting a liquid phase (6) of the fermentation residue I to a process for enlarging the solid surface and for removing dissolved gases, supplying the resulting product to the fermenter of the biogas production plant and/or to a further fermenter, where a fermentation residue II is resulted in the case of supplying the product to the further fermenter, feeding the resulting fermentation residue II to a hydrolysis process step, the fermenter of the biogas production plant and/or a final disposal site or to a further fermenter, which realizes the process for enlarging the solid surface and for removing dissolved gases next to the fermentation, subjecting the resulting fermentation residue II partially to the process for enlarging the solid surface and for removing dissolved gases, and feeding the process product to the further fermenter, the hydrolysis process step, the fermenter of the biogas production plant and/or the final disposal site. The fermentation residue II is subjected to a mechanical solid-liquid-separation in a screw press, screen belt press, decanter centrifuge, membrane filter press, chamber filter press and oscillating sieve (4). A separation grade of 30 mu m to 3 mm is realized with the oscillating sieve. The liquid phase is subjected to a mechanical crushing and/or an ultrasound treatment. The mechanical crushing is carried out by a rotor-stator-system e.g. shear gap homogenizer. A peripheral speed of the rotor of 10-50 m/s is realized with the rotor-stator-system. The ultrasound treatment is carried out with a frequency of 16-1000 kHz. The products of the process steps for enlarging the solid surface and for removing dissolved gases are fed to a further fermenter that is separated from the biogas production plant. The products in the separated fermenter are subjected to a biological degradation under anaerobic conditions within 6 hours to 5 days in the fermenter, and then the products are supplied to the hydrolysis process step of the biogas production plant. The viscous material (5) from the solid-liquid separation is fed to the final disposal site. The flow speeds of the liquid phases are realized to 0.005-2 m/s. An INDEPENDENT CLAIM is included for a device for continuously treating biogenic materials for producing biogas.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of a process flow of a solution.    Fermenter (2)    Fermentation residue I (3)    Oscillating sieve (4)    Viscous material (5)    Liquid phase. (6)