A hybrid treatment of ozonation with limestone adsorption processes for the removal of Fe2+ in groundwater: Fixed bed column study.

During pumping of groundwater to the surface, the reaction between dissolved iron (Fe2+) and oxygen causes oxidation to ferric iron (Fe3+), thereby increasing the concentration of Fe2+. In this research, the potential application of ozonation with limestone adsorption to remove Fe2+ from groundwater was investigated through batch ozonation and fixed-bed-column studies. Groundwater samples were collected from a University Science Malaysia tube well (initial concentration of Fe2+, Co = 1.563 mg/L). The effect of varying ozone dosages (10, 12.5, 15, 17.5, 20, 22.5, and 25 g/Nm3) was analyzed to determine the optimum ozone dosage for treatment. The characteristics of the column data and breakthrough curve were analyzed and predicted using mathematical models, such as Adam Bohart, Thomas, and Yoon- Nelson models. The data fitted well to the Thomas and Yoon-Nelson models, with correlation coefficient r2 > 0.93, but not to the Adam Bohart (r2 = 0.47). The total Fe2+ removed was 72% (final concentration of Fe2+, Ct = 0.426 mg/L) at the maximum dosage of 25 g/Nm3 through ozonation only. However, the efficiency of Fe2+ removal was increased up to 99.5% (Ct = 0.008 mg/L) when the hybrid treatment of ozonation with limestone adsorption was applied in this study. Thus, this integrated treatment was considerably more effective in removing Fe2+ than single ozonation treatment. [ABSTRACT FROM AUTHOR]