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Appendix C – <br />Evaluation of Hydrogen Peroxide with Ozone and Bioremediation for Treatment of <br />Dioxane <br /> <br />Ozone/Hydrogen Peroxide <br />Ozone with hydrogen peroxide was not piloted or further evaluated for treating Dioxane at the <br />City's existing water treatment plant for the following reasons: <br /> <br />1. Typically used for high turbidity waters (surface waters) where the Ultraviolet <br />Transmittance Value (UVT) is too low for UV light to effectively pass through the <br />water and be absorbed by the hydrogen peroxide. Because the City's water contains <br />low turbidity, iron, and manganese downstream of the existing greensand filters, the <br />water produces a very high UVT which is much better suited for UV light with <br />hydrogen peroxide. <br /> <br />2. This process can form assimilable organic carbon (AOC) byproducts that may require <br />an additional treatment process to remove them. <br /> <br />3. Generally requires a larger building footprint. <br /> <br />4. Typically higher O&M costs compared to UV/hydrogen peroxide. <br /> <br />Bioremediation <br />Ex situ bioremediation of groundwater involves putting contaminants in the extracted <br />groundwater in contact with microorganisms in attached or suspended growth biological <br />reactors. Ex situ bioremediation was selected to treat Dioxane in groundwater at the Lowry <br />Landfill Superfund site near Denver, Colorado. Between 1960 and 1980, the site was used for <br />co-disposal of industrial and municipal solid wastes. Industrial waste liquids that contained spent <br />solvents including Dioxane were placed in unlined pits and subsequently contaminated shallow <br />groundwater (Source – EPA Treatment Technologies for 1,4-Dioxane: Fundamentals and Field <br />Applications). <br /> <br />Ex situ bioremediation was not further evaluated for St. Anthony Village as the treatment process <br />was determined to be very difficult to pilot and too costly to implement if it was determined to be <br />an effective treatment technology. In addition, it is possible that the Minnesota Pollution Control <br />Agency (MPCA) and the MDH would not approve this method. There are no known public <br />water systems that utilize bioremediation for treatment of Dioxane. <br />