Removal of Iron from Groundwater Using Granular Activated Carbon Filters

Abstract

The most commonly used iron (Fe) removal mechanism from groundwater involves oxidation-precipitation and floc-filtration worldwide. In this study the oxidation-floc formation mechanism was examined for granular activated carbon (GAC) filter using synthetic groundwater (SGW). SGW was prepared by mixing FeSO4.7H2O with tap water which had the initial dissolved oxygen (DO) level of 5 mg/L. Batch experiment including isotherm and kinetic study was carried out to find out the adsorb ability of GAC. Column test was conducted at different phases to identify the influence of initial concentration of Fe, hydraulic retention time (HRT) and aeration supply to the system. Widely used up-flow mode was used to supply SGW using peristaltic pump. The reduction of adsorption amount with the increment of GAC weight was identified from the result of isotherm study and it was observed that the experimental results fit to the pseudo-second order kinetics model with the adsorption amount of 1.36 mg/g. Column experiments concludes that the effluent Fe concentration reduced from 0.05 to 0.03 mg/L when increasing the concentration of Fe approximately from 1 to 3 mg/L. The reduction of HRT from 7 hours to 3.5 hours reduced the iron removal efficiency from 98.9% to 98.4%. The air supply to the system with the flow rate of 3.5 L/min did not show any improvement in Fe removal efficiency. Overall, the effluent achieved the World Health Organization (WHO) drinking water standard at all the phases which shows that oxidation precipitation is more suitable for Fe removal from groundwater