NOVELTY - Cleaning of contaminated environmental wasteland, comprises, e.g., producing a contaminated, liquid and/or humid digestate and biogas (7) by fermenting contaminated biomass, in at least one fermenter of a biogas plant (5), supplying the contaminated liquid and/or humid fermentation residue to at least one drying device (9), supplying the contaminated dried digestate of the biogas plant to a combustion- and/or gasification device (11), and withdrawing and separating contaminated ash accumulated in the combustion- and/or gasification device, preferably supplied to a repository.    USE - The method is useful for reducing the radiation exposure from radioactive contaminated environmental wasteland (claimed).    ADVANTAGE - The method can be performed in an efficient, simple and reliable manner, while reducing the emplaced waste.    DETAILED DESCRIPTION - Cleaning of contaminated environmental wasteland, comprises producing a contaminated, liquid and/or humid digestate and biogas (7) by fermenting contaminated biomass, preferably radioactive contaminated plant biomass, in at least one fermenter of a biogas plant (5), supplying the contaminated liquid and/or humid fermentation residue to at least one drying device (9), in which it is dried to contaminated dried digestate with a defined predetermined residual moisture, supplying the contaminated dried digestate of the biogas plant to a combustion- and/or gasification device (11), in which the contaminated dried digestate is combusted and/or gasified, and withdrawing and separating contaminated ash accumulated in the combustion- and/or gasification device, preferably supplied to a repository. An INDEPENDENT CLAIM is also included for a plant for purifying the contaminated environmental wasteland, preferably for reducing the radiation exposure from radioactive contaminated environmental wasteland and/or for performing the method, comprising a biogas plant, at least one drying device downstream of the biogas plant, a combustion- and/or gasification device downstream of the drying device, and a trigger device for separating and removing the ash resulting in the gasification device, as waste.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the plant for reducing the radiation exposure of radioactively contaminated environmental wasteland.    Wood (3)    Biogas plant (5)    Biogas (7)    Drying device (9)    Combustion- and/or gasification device (11)