AWWA JAW30355

Research was conducted to provide a better understanding of the mechanisms of Mn(II) removal in oxide coated filters. The kinetics of Mn(II) sorption by MnOx(s)-coated filter media were quantified as a function of solution pH, MnOx(s) surface concentration, and free chlorine concentration of the filter-applied water. Rate of Mn(II) sorption was positively correlated to the number of available surface adsorption sites within a filter. Free chlorine had a very significant role in defining both the rate and ultimate extent of Mn(II) removal. Addition of chlorine to the filter-applied water oxidized the adsorbed Mn(II), thereby continually regenerating the media surface. In the absence of free chlorine, Mn(II) removal was by adsorption only; no evidence of auto-oxidation of Mn(II) was noted. Practical applications of the work to the operation of water treatment facilities concern the selection of oxidant dosing locations, the impact on filtration hydraulics, and the determination of media generation requirements. Includes 10 references, tables, figures.