Treatment of Iron from Groundwater by Ozonation: Influence of Hardness as a Scavenger

Abstract

This study assesses the efficiency of using ozone technology to treat iron from groundwater while hardness acts as a radical scavenger. Batch experiments were conducted to determine the effects of initial pH 6, 7 and 8, and hardness of 300, 400 and 500 mg L^-1 and kinetic analysis. The optimum conditions were found to be initial pH of 8 and hardness of 300 mg L^-1. The removal efficiency of iron by ozonation was 99.97%, which was higher than that of air without ozone applied (83.67%). However, the presence of hardness and tert-butanol (TBA) had a negative effect on the oxidation of iron from groundwater. By increasing the carbonate hardness concentration, the oxidation rate of iron by ozone was reduced. The results of kinetic analyses indicated that the reactions of ozonation to remove iron from groundwater followed a pseudo-first order kinetic model with a rate constant of 0.0881 min^-1, while air without ozone applied (aeration) was 0.0051 min^-1. This finding suggests the potential use of ozone to remove iron from groundwater. Iron concentration from groundwater samples treated by ozonation have met the World Health Organization (WHO) guidelines (0.3 mg L^-1).