AWWA ACE58262

The City of Fairborn, Ohio, located roughly 70 miles northeast of Cincinnati, has a water service area population of 32,000. The community's primary source of water is the 5.0 million gallons per day (mgd) Fairborn Water Treatment Plant (FWTP). The FWTP obtains raw water from four wells located in a well field adjacent to the Mad River. These sources, though not considered under the influence of surface water, have elevated levels of iron and manganese. Treatment presently consists of iron and manganese removal via oxidation through aeration, followed by settling, permanganate and polymer addition, AND by gravity filtration by conventional sand media and chlorination. Unfortunately, the current treatment process has been only marginally successful in removing iron and manganese. To optimize iron and manganese removal at the existing FWTP and reduce or eliminate the use of expensive oxidants like permanganate, the City authorized the construction of a pilot plant. The pilot plant consisted of two, four-inch clear PVC columns constructed within the FWTP's filter gallery. By constructing the plant in this location, the water supplied to the pilot tubes (including backwash water) was identical to that supplied to the plant's existing filters. The pilot study investigated iron and manganese removal by various media, flow rates and oxidation methods. Media analyzed in the pilot plant included conventional sand (activated to induce a Natural Greensand Effect or NGE), greensand and pyrolusite. Oxidation methods included the use of aerated versus non-aerated water and the addition of chlorine prior to filtration. This paper describes the results of the FWTP pilot tests. The effectiveness of the various media at various filtration rates are then examined. The optimal filter medium is presented and revised operating processes recommended. Finally, the cost savings associated with implementing these recommendations plantwide are projected. Includes 6 references, table, figures.