NOVELTY - The procedure for removing hydrogen sulfide, ammonia and carbon dioxide from biogas of a biogas plant (1), comprises supplying hydrogen peroxide to the biogas in a hydrogen sulfide-cleaning stage (K02), and supplying sulfuric acid, which is formed by the reaction of hydrogen peroxide and hydrogen sulfide in the hydrogen sulfide-cleaning stage, to a ammonia cleaning stage, in which ammonium sulfate is formed by the reaction by ammonia with sulfuric acid. The hydrogen sulfide-cleaning stage is connected downstream to an adsorption stage as safety filters.    USE - Procedure for removing hydrogen sulfide and ammonia from biogas of a biogas plant (claimed).    ADVANTAGE - The procedure ensures simple and cost-effective cleaning of biogas of a biogas plant with high efficiency as well as provides safe removal of hydrogen sulfide and ammonia from the biogas without any loss of methane.    DETAILED DESCRIPTION - The procedure for removing hydrogen sulfide, ammonia and carbon dioxide from biogas of a biogas plant (1), comprises supplying hydrogen peroxide to the biogas in a hydrogen sulfide-cleaning stage (K02), and supplying sulfuric acid, which is formed by the reaction of hydrogen peroxide and hydrogen sulfide in the hydrogen sulfide-cleaning stage, to a ammonia cleaning stage, in which ammonium sulfate is formed by the reaction by ammonia with sulfuric acid. The hydrogen sulfide-cleaning stage is connected downstream to an adsorption stage as safety filters, so that the biogas is cleaned in two stages on or under a given hydrogen sulfide limit-value. The biogas in a hydrogen sulfide-cleaning stage (K01) is prepurified on a hydrogen sulfide concentration of 50 mg/Nm3 and then the prepurified biogas is cleaned in the adsorption stage on a hydrogen sulfide concentration of less than or equal to 3 mg/Nm3. The ammonia removal in the ammonia cleaning stage is carried out at a pH value of the sulfuric acid having wash solution of 2 to 4. The dosing quantity of the sulfuric acid is predetermined so that the ammonia proportion in the biogas after the ammonia cleaning stage is less than or equal to 1 mg/Nm3. The hydrogen sulfide cleaning stage is connected downstream to the ammonia cleaning stage. The biogas, which is cleaned from hydrogen sulfide and ammonia, is supplied to a carbon dioxide cleaning stage (K03). The carbon dioxide is extracted from the biogas in the carbon dioxide cleaning stage by means of physical or chemical absorption with an aqueous amine solution. The biogas in the carbon dioxide cleaning stage is cleaned to a carbon dioxide concentration of less than or equal to 6 vol.%. An absorbent is cooled down to a temperature of 10degreesC or below before supplying into the carbon dioxide cleaning stage. The absorbent loaded with the carbon dioxide is condensed to a given pressure, is heated to 165-175degreesC in a thermal-oil heat exchanger and then supplied to a desorption stage, in which the bound carbon dioxide is removed from the absorbent through relaxation. The heat transfer medium is heated by means of exhaust heat from combined heat and power units of a gas cleaning plant (2) and then supplied to the heat exchanger. The heat of the thermal oil production is supplied via the heat exchanger to a fermenter (3) of the biogas plant. The carbon dioxide present after the desorption stage is condensed and the condensation heat is thermally coupled to the fermenter. The carbon dioxide obtained from the carbon dioxide cleaning stage is liquefied and then supplied to a storage container for liquid carbon dioxide. The storage container is connected downstream to a device for the production of dry ice or another utilization mechanism. The cleaned biogas is partly supplied to the combined heat and power units and to a natural gas network. The biogas is dehumidified and/or odorized before the supply to the natural gas net. The cleaned biogas is stretched before the supply into the natural gas network by addition of further gas components on a given methane content-limit value for a given degree of purity and/or calorific value. An INDEPENDENT CLAIM is included for a gas cleaning plant for the cleaning of biogas of a biological gas plant.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of a gas cleaning plant coupled with biogas plant (Drawing includes non-English language text).    Biogas plant (1)    Gas cleaning plant (2)    Fermenter (3)    Pipeline. (4)