TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The method uses a packed bed with the above properties, with a scrubbing contact time of at least 40 (preferably 50-400) seconds. The CO2 concentration in the biogas is measured and the draw-off flow rate for methane and therefore the contact time is adjusted according to the determined value; the biogas flow rate is adjusted to 0.01-0.1 m/s based on the free column cross-section. The wash liquid (WL) is an amine solution and the contact time is influenced by the amine concentration in WL. The water content of WL is kept constant by adjusting the biogas temperature and the temperature of the circulating WL; these are preferably the same temperature. Desorption is carried out at 8-20 bar and up to 180degrees C, using steam or thermal oil as heat exchange medium. Ammonia, carbon oxysulfide, hydrogen sulfide and sulfur dioxide are removed before feeding the biogas into the column. Preferred Device: The column container has a length to diameter ratio of 4-20, preferably 10-20, and the pellets in the packed bed have an average diameter of 5-8 mm. The column is connected to a compressor for adjusting the methane draw-off rate and the biogas contact time. EXAMPLE - Biogas was processed in an absorption column (12 m x 1.75 m diameter; L/D ratio = 4.57) containing a packed bed (height = 8 m; volume = 19.23 m3) of polypropylene pellets with an average diameter of 5-8 mm and a specific surface of 800 m2/m3. The biogas was fed into the base of the column at 500 Nm3/h, 25degrees C and 1015 mbar with a flow rate of 0.062 m/s based on free column cross-section, giving a space loading factor of 26.3; the gas composition was 53.5 vol.% methane, 44.0 vol.% carbon dioxide, 2.5 vol.% water and 150 ppm hydrogen sulfide. A 20 wt.% aqueous solution of diethanolamine was sprayed into the top of the column at 25degrees C at the rate of 15 m3/h and then regenerated and recirculated into the column. The biogas/liquid contact time for almost complete removal of CO2 and sulfur compounds was 138 seconds. Methane was removed from the top of the column at 0.033 m/s with the aid of a compressor which was regulated according to the measured CO2 concentration in the methane. The product comprised 97.3 vol.% methane, 0.2 vol.% CO2, 2.5 vol.% water and 1 ppm H2S.