IMPROVING THE PERFORMANCE OF RAPID SAND FILTER USING COARSER AND MORE UNIFORM MEDIA WITH POLY-ALUMINUM CHLORIDE AS FILTER AID

The use of filter aid to improve the performance of conventional rapid sand filter is a comparatively recent development in drinking water treatment. Use of filter aid generally results in reduction in ripening period, higher turbidity removal as well as relatively stable effluent quality while the limitations includes the reduction in filter rate as well as reduction in filter run.To overcome the limitations attempt is made to devise the RSF with media having higher effective size (around 0.85mm) and lower coefficient of uniformity (around1.2) as compared to conventional filter media, with use of poly-aluminum chloride (PACl) as a filter aid. The study was conducted at one of the water treatment plant at Ichalkaranji, Maharashtra by installing a pilot scale model.Various dosages were tried to determine the better performing dose. High turbidity removal, extended filter run, and low head loss as compare to conventional rapid sand filter was observed. The net backwashing requirement also was reduced