Thus, nitrogen dioxide and nitrous oxide emissions from the steel industry, which uses nitric acid in a pickling process, can be strongly reduced. At the end of the last century, acid rain was a huge environmental problem in many developed countries. One of the main reasons was the emission of sulfur dioxide (SO2) in exhaust gases. Mercaptans, hydrogen sulfide (H2S) and sulfur dioxide (SO2) removal from effluents or off-gases is achieved by utilization of a wet scrubber with hydrogen peroxide. It is also used to reduce toxicity and odors at paper mills, rendering plants, metal smelters, pharmaceutical, pesticide, chemical manufacturing or petrochemical facilities.