Abstract: A method for oxidizing odorous constituents of contaminated gas with minimum consumption of the oxidizing agent. Apparatus is disclosed for causing contact between the contaminated gas and the scrubbing liquid by means of opposed flow through a porous bed of packing material. The method is primarily useful in controlling odorous emissions from rendering plants, fish processing plants, asphalt plants, and other plants in which aldehydes, fatty acids, ketones, mercaptans, amines, hydrogen sulfide, sulphur dioxide, nitric oxide, phenols or other pollutants are emitted. Chlorine in the form of sodium hypochlorite in a concentration of 5-50 ppm is the preferred oxidizing agent. Consumption of the oxidizing agent is minimized by continuously purging 1-5% of the scrubbing liquid to thereby promptly remove precipitates and other solids.