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5 <br />5.1 <br />5.2 <br />5.3 <br />5.4 <br />The use of detention and aeration in Train 2 did not provide a significant treatment advantage <br />over Train 1 in removing iron and manganese. There also wasn't a significant difference in <br />treatment effectiveness between the two filter media types, although Filter 4 saw the spike in <br />manganese that was above the secondary standard and NADH HBV. <br />Conclusions and Recommendations <br />The SEH pilot water plant was able to treat water from Well No. 3 and Well No. 4 to <br />concentrations below the EPA secondary standards for iron and manganese, as well as the INADH <br />HBV for manganese. Implementing either treatment trains at full-scale would allow the City of <br />Ramsey to provide aesthetically pleasing as it relates to iron and manganese, as well as provide <br />safe drinking water to the residents as it relates to manganese. <br />Aeration <br />Aeration of the water provided better results in terms of iron removal for Well No. 3, which had <br />much higher raw water iron levels than Well No. 4, but provided similar results in terms of iron <br />removal for Weil No. 4. It is expected that the benefits of aeration will be more pronounced in <br />water quality similar to that of Well No. a Based on the results and on previous experience, the <br />use of an aerator may be preferred as it provides an additional layer in the removal or iron, and <br />may also provide additional treatment benefits such as the removal of dissolved gases like <br />hydrogen sulfide. <br />Detention <br />The addition of a detention tank did not provide a significant difference in treatment effectiveness <br />for iron and manganese removal, but it did allow for the potassium permanganate dosage to be <br />lowered. Although 30 minutes of detention was suitable for the removal of iron and manganese, <br />and allowed for the reduction in the potassium permanganate dosage, it is not needed to provide <br />quality water for the City of Ramsey. If a water treatment plant is pursued, the City should <br />compare the cost savings of reducing the potassium permanganate dosage with the construction <br />cost of a detention tank. <br />Chemical Feed <br />The pilot study evaluated the use of chlorine and potassium permanganate as oxidants. Feed <br />rates are within normal ranges for the type of water treated. It is recommended to use these <br />chemicals for a full-scale design, although chlorine may be fed as sodium hypochlorite solution or <br />gas chlorine, and potassium permanganate may be fed as sodium permanganate instead. <br />Filtration <br />Both filter media types were effective in removing iron and manganese and successfully operated <br />at a loading rate of 3.0 gpm/ft2, but there wasn't a significant difference in effectiveness. <br />Although there wasn't a significant difference between the two filter media types, SEH <br />recommends the use of 12 inches of anthracite over 18 inches of Greensand PFUSTM, rather than <br />12 inches of anthracite over 18 inches of silica sand for full-scale filters. This is because <br />Greensand PlusTm is a filter media that is coated with manganese dioxides that further aid in the <br />removal of manganese. <br />PILOT STUDY REPORT RAMSY 154354 <br />Page 8 <br />