Abstract: A feed stream of digester gas from an anaerobic process is compressed to a predetermined pressure of about 300 p.s.i.g. and fed into an absorber at that pressure. Carbon dioxide and hydrogen sulfide impurities of this feed stream are absorbed in the absorber by counterflowing water. Water from the absorber may be fed back to an activated sludge sewage treatment facility where the hydrogen sulfide is oxidized and the carbon dioxide released. As an alternative to the absorber, hydrogen sulfide is oxidized in an iron sponge reaction. Alternately, these contaminants are stripped with air and vented. Treated gas from the absorber, essentially methane, is either compressed for introduction into storage tanks, or dried and used as pipeline gas. In the dryer, adsorbed moisture is removed by air, followed by a purge with treated gas.