Potential of Granular Activated Carbon Filters for Iron Removal from Groundwater

Abstract

The most commonly used iron (Fe) removal mechanism from groundwater involves oxidation-precipitation and adsorptive-filtration worldwide. In this study the oxidation-floc formation mechanism was examined for granular activated carbon (GAC) filter using synthetic groundwater (SGW). Batch experiment including kinetic and isotherm study were 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. It was observed that the experimental results for kinetic experiment best fit to the pseudo-first order kinetics model with the adsorption amount of 8.54  10-5 mg/g and the reduction of adsorption amount with the increment of GAC weight was identified from the result of isotherm study. 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 99% 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 granular activated carbon filters are more suitable for Fe removal from groundwater