Removal of heavy metals by conventional water treatment plants using poly aluminum chloride

Abstract

In this study, trace heavy metals, such as aluminum (Al), barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mn), nickel (Ni), lead (Pb), antimony (Sb), vanadium (V), and zinc (Zn) were investigated in the water of the Karun River that enters the water treatment plants (WTP1 and WTP2) in Ahvaz City, Iran. Removal efficiency of these heavy metals was assessed in various units of WTP1 and WTP2, as well. For this purpose, water samples were collected from four different points of the WTP1 and WTP2, namely, the influent (raw water, RW), the effluent of the clarifier (clarifier effluent, CE), and the effluent of the filter (filter effluent, FE). A total of 72 water samples were collected and analyzed for heavy metals using ICP-OES apparatus. The results indicated that all RW samples contain Ba, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn within the US EPA maximum contaminant levels (MCLs), except Al, Fe, Mn, and Sb that crossed the MCLs. High levels of Al (649.9 (±171.6) µg/L, 806.4 (±135.1) µg/L), Fe (484.95 (±127.05) µg/L, and 529.7 (±119.6) µg/L) were found in finished water of WTP1 and WTP2, respectively. Experimental results showed that level of all studied heavy metals except Al reduced in WTP1 and WTP2 effluent. From the observed data, it is found that effluent Al concentration was over influent Al concentration in both WTP1 and WTP2. It is concluded that using PACl as coagulant in WTP1 and WTP2 can increase concentration of aluminum.