The application of Polyaluminium Ferric Chloride for Turbidity and Color Removal from Low to Medium Turbid Water

Background & Aims of the Study: Coagulation is an essential process for the removal of fine particulate matter in water treatment. Polyaluminium ferric chloride (PAFC) is a composite inorganic polymer of Aluminium and ferric salt. This study was conducted to find out the optimum coagulation conditions for the removal of turbidity, color and organic matter (UV absorbance) in low to medium turbid water . Materials & Methods: For evaluation of the coagulation procedure, conventional Jar Test apparatus was used. Low to medium synthetic turbid water (10 to 60 NTU) was prepared by kaolin and river bed soli. Then all samples were analyzed for residual turbidity, true color, UV absorbance, residual Aluminium (Al 3+ ), Iron (Fe 2+ ), and residual heavy metals like Arsenic, Lead, Nickel and Chromium. Results: Optimum dose of PAFC for first, second, third and fourth sample with initial turbidity of 10, 20, 40 and 60 NTU was 7, 10, 11 and 11 mg/L respectively. After coagulation with optimum dose, residual turbidity in treated water was 0.4, 0.34, 0.28 and 0.3 NTU respectively. Also color removal efficiency for mentioned samples was 97%, 98%, 99% and 99% respectively at optimum dose PAFC. Optimum pH for maximum removal with PAFC was 7.8 (pH range 7.5 to 8). Conclusions: Polyaluminium ferric chloride has a good efficiency for removal of turbidity, color and organic matter. It can be select as a new coagulant for water treatment plants. Also residual Aluminium, Iron and some heavy metals (chromium, lead, cadmium and nickel) in treated water was investigated. Their concentration in treated water didn’t have any adverse effect on consumer health according to their standards in EPA.