To neutralize the sewage containing simple and complex metal cyanides the compounds with «active» chlorine are usually used. The oxygenization of complex metal cyanides together with chlorinated lime and air oxygen takes less time and leads to the improvement of the organoleptic properties of cleaned water. The method of decreasing pollution and a device for sewage purification are presented in the article. Its installation allows to decrease chlorinated lime consumption by 40 times with simultaneous oxygenizing of cyanide by air oxygen and chlorinated lime. It is also possible to decrease the formation of chlorine-organic compounds and increase the degree of heavy metal hydroxide settling.