Method of treating contaminant ions in an aqueous medium with electrolytically generated ferrous ions, and apparatus therefor

摘要

An aqueous medium containing contaminant ions such as hexavalent chromium ions is treated by introducing electrolytically generated ferrous ions which are preferably generated in water acidified to a low enough pH to prevent the formation of flocculent material. The ferrous ions reduce the hexavalent chromium ions to a trivalent state, and thereafter alkaline material is introduced into the medium to raise its pH high enough to cause insoluble chromic hydroxide and ferric hydroxide to precipitate. The apparatus includes a ferrous ion generator for recirculating liquid through an electrolytic cell and a receptacle, from which receptacle liquid for end use can be withdrawn and to which makeup water and acid can be added.