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St. Anthony 2040 Comprehensive Plan Chapter 8: Water Supply <br />161 <br /> <br />Water Treatment <br />Water is pumped from the three wells to the St. Anthony WTP, which has <br />a treatment capacity of approximately 5.0 million gallons per day. The <br />plant was originally constructed in 1965 and was subsequently upgraded <br />in 1995 and expanded in 2016-2017 with an Advanced Oxidation <br />Process (AOP). It includes three treatment processes: <br />1. Filtration – Iron and manganese are removed by two horizontal <br />pressure filters that contain greensand filter media. Chlorine and <br />permanganate are applied before filtration, the chlorine to oxidize <br />and preciptate iron and the permanganate to oxidize and <br />preciptate manganese prior to filtration. <br />2. Advanced Oxidation Process (AOP) – An advanced oxidation <br />process that utilizes hydrogen peroxide and ultravioliet (UV) light <br />treats 1,4-dioxane, a carinogenic organic contaminant, that exists <br />in the City’s raw water source. Hydrogen peroxide absorbs UV <br />light and forms hydroxyl radicals that oxidize and breakup the 1,4- <br />dioxane into non-toxic compounds. <br />3. Granular Activated Carbon – Granular Activated Carbon (GAC) <br />filters adsorb organic contaminants such as trichloroethylene <br />(TCE) and dichloroethane (DCA) in addition to taste and odor <br />compounds. The GAC filters also quench and remove any <br />exceess hydrogen peroxide that is not consumed during the <br />advanced oxidation process. <br />Chlorine, fluoride, and polyphosphate are applied at the end of the <br />treatment train to disinfect, prevent tooth decay, and inhibit pipe <br />corrosion, respectively. <br />