That phosphorus has been removed more from water in purification process can result in higher grade of biological stability of the effluent tap water, especially for the water plant when using surface water source. This study conducted the experiments of phosphorus removal by three coagulants including aluminum chloride, aluminum sulfate and poly aluminum chloride. The results indicated that the poly aluminum chloride is the preferred one that could remove phosphorus up to 80%, followed by aluminum chloride and aluminum sulfate. The lowest proportion of aluminum quality to phosphorus quality is 63 as using poly aluminum chloride, followed by aluminum chloride and aluminum sulfate. It is suggested that the poly aluminum chloride should be the best option to remove phosphorus in water plant.
 Sathasivan, A., Ohgaki, S., Yamamoto K. and Kamiko, N. (1997) Role of Inorganic Phosphorus in Controlling Regrowth in Water Distribution System. Water Science Technology, 35, 37-44.
 Auvray, F., Hullebusch, E.D., Deluchata, V. and Baudu, M. (2006) Laboratory Investigation of the Phosphorus Removal (SRP and TP) from Eutrophic Lake Water Treated with Aluminum. Water Research, 40, 2713-2719.
 Liang, C., Deng, H., Su, Y. and Li, H. (2006) Study on the Enhanced Coagulation Effect of Polyferric Sulfate and Aluminum Sulfate for Removal of Humic Acid. Water Purification Technology, 25, 27-30.
 Xie, W., Wang, Q., Ma, H., Ohsumi, Y. and Ogawa, H.I. (2005) Study on Phosphorus Removal Using a Coagulation System. Process Biochemistry, 40, 2623-2627.