Removal of lindane as a health-toxic pesticide in drinking water by slow sand filtration

Abstract

Lindane is applied in agriculture as insecticide and in veterinary medicine to control the insect-borne diseases. Contact to this synthetic chemical has various adverse effects on human health. This study was conducted to remove lindane in water by slow sand filtration (SSF). The effects of different parameters including lindane concentration, turbidity, filter bed depth and Schmutzdecke type were assessed on the removal of lindane by SSF. The results indicated that the filter media caused the removal of 85.4%, 95.4% and 100% inlet lindane concentration of 200, 100 and 20 µg/L, respectively, over 1 d after operation. These removal efficiencies were approximately constant by increasing operation period up to 5 d. Water turbidity up to 5 NTU had an insignificant effect on the removal of lindane. The filter depth more than 20 cm had negligible effect on the removal of lindane. The findings also showed that the filter media decreased 98.0% and 98.3% of water turbidity and heterotrophic plate count, respectively. The removal efficiency of lindane by the SSF-modified Schmutzdecke layer was nearly 15% higher than that of SSF with the natural Schmutzdecke layer. On the basis of the results, SSF can meet the WHO guideline for lindane in drinking water only in low concentration (up to 20 µg/L).