Ozonation of dissolved manganese in the presence of natural organic matter

Oxidation of Mn2+ by ozone was studied with respect to the effects of natural organic matter (NOM) and initial Mn2+ concentrations on post-ozonation dissolved Mn residuals. For an initial Mn2+ concentration of 200 mug/L, dissolved Mn residuals < 10 <mu>g/L were attainable only in the absence of NOM. The presence of NOM complicates the use of ozone for Mn2+ removal by increasing dosage requirements, thus increasing the potential for the formation of permanganate ion, MnO4-. For a constant TOC concentration of 3.4 mg/L, ozonation of natural water spiked with an initial Mn2+ concentration of 1000 mug/L produced dissolved Mn residuals < 10 <mu>g/L. At lower initial Mn2+ concentrations (60-200 mug/L), dissolved Mn residuals following ozonation were consistently 20-30 mug/L.