Natural organic matter(NOM) removal from surface water by coagulation

Poly aluminum chloride sulfate（PACS） with different SO 2- 4/Al 3+ mole ratios and bacicity（γ） of 2 0 was synthesized using AlCl 3\56H\-2O, Al\-2（SO\-4）\-3\518H 2O and Na 2CO 3 as raw materials. The effect of SO 2- \-4/Al 3+ ratio on the performance of PACS for removal of natural organic matter（NOM） with humic rich actual water was examined. It was found that PACS with SO 2- \-4/Al 3+ mole ratio of 0.0664 achieved the best NOM removal results and was selected to investigate its performance in comparison with PAC, FeCl 3 and alum（Al 2 （SO 4） 3·18H 2O）. The experimental results showed that the optimum NOM removals were achieved at pH 5.0\8.2 and the dose of about 5 0 mg/L as Al both for the selected PACS and PAC, at pH 5 0\6 0 and the dose of about 7 0 mg/L as Fe for FeCl 3, and at pH 5 0\7 0 and the dose of about 7 0 mg/L as Al for alum, respectively. At the optimum conditions, the selected PACS achieved the best NOM removal result, followed by PAC, FeCl 3, and then alum. The concentration of residual aluminum in treated water by the selected PACS and PAC under the optimum coagulant conditions was approximately 115 μg/L, which can completely comply with the regulated limits.