Soluble Manganese Removal on Oxide‐Coated Filter Media

Abstract

Laboratory‐scale filtration studies were conducted to assess the potential for soluble manganese removal within oxide‐coated, mixed‐media filtration systems. Filter column experiments employed both new anthracite coal and sand as well as oxide‐coated media obtained from three full‐scale water treatment facilities. Soluble and total manganese removals were evaluated as a function of parameters such as pH, presence or absence of an oxidant in the filter‐applied water, quantity and oxidation state of the filter media surface oxide coating, and temperature. Results indicated that Mn2+ removal was rapid and efficient under a variety of solution conditions. Alkaline pH conditions promoted efficient removal of Mn2+ on the oxide surface. Free chlorine likewise promoted soluble manganese removal on the media surface under both alkaline and acidic pH conditions. Stronger oxidants such as KMnO4, ClO2, and O3 resulted in Mn2+ oxidation immediately upon addition to the filter‐applied water. In these instances, manganese removal was accomplished by retention of colloidal MnOx(s) within the filter. Low‐temperature conditions did not appear to inhibit Mn2+ removal potential. The practical implications of this work for full‐scale treatment operations are also discussed.