Advantages of Combined Oxidants in Water Treatment

摘要

Combined oxidants use in water treatment has been increasing because of more stringent drinking water regulations. First of all, this paper will present a literature review of other studies concerning the advantages of combined disinfectants. This paper will also report on three laboratory and plant studies performed at two water plants in El Paso, Texas and a water plant in Aurora Colorado. All of these studies showed synergistic benefits of combined oxidants in reducing THMs and chlorite levels while increasing disinfection capability in the same disinfection zone and reducing bromate formation at the ozone water plant. The combined oxidants evaluated were chlorine dioxide and chlorine at the Canal Plant in El Paso; chlorine dioxide and chloramines treatment at Aurora Colorado Water Plant in reducing chlorite and THMs levels while increasing disinfection credit; and chlorine dioxide as a pre-oxidant to ozonation to reduce bromates in water with excessive bromide levels. Linear regression equations were developed from lab and plant studies to predict THMs formation and bromate formation. Combined chlorine dioxide and chlorine disinfection in the same zone showed the advantages of more chlorite reduction while increasing disinfection credit and providing a double barrier safety margin in the disinfection capability of the plant.