Ferric chloride is an important water treatment chemical, which produces a variety of hydrolyzed products after reacting with hydroxide alkalinity in water. It is an efficient and cheap flocculant for urban sewage and industrial wastewater treatment. It has significant precipitation of heavy metals and sulfide. Decolorization, deodorization, oil removal, sterilization, phosphorus removal, reduction of effluent COD and BOD, etc.