Making a business case for mixed oxidants
FOR YEARS, Prestonsburg, Ky., treated its water with chlorine gas stored on-site in several 1-ton cylinders. Several times a year, a box truck or open trailer would drive through town to deliver chlorine gas cylinders to the treatment plant. The 3.5-mgd facility lies in a residential area next to a middle school and a quarter mile from a nursing home, so transporting and storing the hazardous chlorine gas was a big concern for such a populated area. Additionally, because of the large volume of chlorine used, the city had to comply with US Environmental Protection Agency requirements for a risk management plan. The plant also struggled to stay within the USEPAcompliance limits of 80 μg/L of total trihalomethanes (TTHMs) during periods of high heat and chlorine demand.