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MEMO TO: Clerk -Administrator an,I City CrnurciI <br />FROM: Director of Public Works/Community Development <br />DATE: June 9, 1986 <br />SUBJECT: WELL NO. 3 MANGANESE REMOVAL <br />As you may recall, the City has conducted 3 pilot studies on the <br />water from Well No. 3. The pilot studies used current and innova- <br />tive technologies to try to remove manganese from the drinkinq <br />water. The completed pilot studies are as follows: <br />Potassium permanganate chemical feed utilizing existing <br />silica sand filter media. <br />2. Potassium permanganate chemical feed utilizing green sand <br />filter media. <br />3. Ozone feed utilizing existinq filter media. <br />Manganese ,.,...,.,1 to lrsn than the Minnesota Department of health <br />(MHD) recommended standard of 0.05 parts per million (PPM) could <br />' not be maintained for any pilot study. On the average, Pilot <br />Study No. I produced the lowest manganese concentration in treated <br />water. The manganese concentration averaged approximately 0.09 <br />PPM. <br />Well No. 3 raw water has a manganese concentration of approxi- <br />mately 1.0 PPM. With treated water averaging 0.09 PPM, the <br />removal efficiency is approximately 90 percent. We cannot hope to <br />obtain better removal efficiencies utilizing the potassium perman- <br />ganate chemical feed system. However, the average manganese <br />effluent of 0.09 PPM is approximately 2 times the MHD recommended <br />standard of 0.05 PPM. <br />Installing a potassium permanganate chemical feed system for Well <br />No. 3 is not a permanent solution. At the present time, there is <br />no treatment system capable of lowering the manganese concentra- <br />tion in Well 13 water to below MHD recommendations. Therefore, I <br />recommend that we consider installing a potassium permanganate <br />chemical feed system on a temporary hasis until the industry finds <br />A way to remove more manganese from drinking water. Ozone techno- <br />logy in the united States is still in an infancy stage. In the <br />near future, I hope that this technology can be utilized to remove <br />manganese in Well No. 3 drinkinq water to within the limits recom- <br />mended by the Mill). <br />The presence of iron and manganese in drinking water is not hazar- <br />dous to health. rnnsequently, iron and manganese are limited, <br />not becerjge of physio1 ngical hazardi, but rather f^r aesthetic <br />