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

Article type: Research Article

Authors: GAO, Bao-yu | YUE, Qin-yan

Affiliations: School of Environmental Science and Engineering, Shandong University, Jinan 250100, China

Note: [] Corresponding author. E-mail: bygao@sdu.edu.cn

Abstract: Poly-aluminum-chloride-sulfate (PACS) with different SO_4^{2-}/Al^{3+} mole ratios and bacicity (γ) of 2.0 was synthesized using AlCl_3· 6H_2O, Al_2 (SO_4)_3· 18H_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_4^{2-}/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.

Keywords: coagulation, humic-rich water, NOM removal, residual aluminum

Journal: Journal of Environmental Sciences, vol. 17, no. 1, pp. 119-122, 2005