Fenton process for the combined removal of iron and organic micropollutants in groundwater treatment

Abstract

Fenton process, known as Advanced Oxidation Process for the degradation of organic pollutants in waste and drinking water, was studied for the combination of iron removal and pesticide control in anaerobic groundwater. The combined effect of aeration and rapid sand filtration, which are commonly applied in groundwater treatment, was studied in a pilot plant. Pesticide degradation was performed on laboratory scale. It was found that addition of 2 mg/L H2O2 prior to aeration improved the removal of iron without hindering the filtration processes of manganese removal and nitrification. Under these conditions, the laboratory-scale tests showed pesticide degradations of up to 80% (influent concentration 1.6-2.5 μg/L). Dosing 8.5 mg/L H2O2 all selected pesticides were converted more than 80%. However, this dose appeared to have an adverse effect on the removal of iron and manganese and the nitrification process. This is attributed to the presence of relatively high concentrations H2O2 in the water entering the rapid sand filter. By filtration AOC, formed during oxidation with the low H2O2 dose, was reduced from about 70 μg/L to about 15-20 μg Acetate-C/L. Bromate formation did not occur. Residual H2O2 varied from 0.1-0.2 mg/L (2 mg/L H2O2 dose) to 0.2-0.4 mg/L (8.5 mg/L H2O2 dose) which is higher than the proposed guideline of 0.019 mg/L.