Comparison of Poly Aluminum Chloride, Aluminum Sulfate and Ferric Chloride in Removal of TOC and Total Coliform

Coagulation is one of the important processes in water treatment plants. The experts attempt to find out both low cost and high efficient coagulant in water treatment plants. The coagulants which are widely used in coagulation process, are inorganic salts, specially Iron and Aluminum salts.. Aluminum Sulfate and Ferric Chloride are two coagulants which are used in many water treatment plants in Iran. Recently there is a tendency to use a new coagulant which is called Ploy Aluminum Chloride (PAC) which are used in many other countries such as Canada, America, China and England. The purpose of this study was comparison of PAC, Alum and Ferric Chloride removal of TOC and Total coliforms as indicators of chemical and biological pollution of water and to find out optimum concentrations for turbidity removal of raw water of Esfahan water treatment plant.In this study 20 samples of raw water were taken during 4 months from Esfahan water treatment plant. At first, the amounts of total coliforms and TOC was measured. Then the optimum coagulant dosage for turbidity removal was obtained using jar test apparatus Final TOC and total coliform concentrations were measured after jar test study.The results of this study show that Ferric Chloride and PAC in removal of turbidity, total coliforms and TOC are more efficient than Alum. It was also found Ferric Cholide in removal of TOC is better than PAC. Due to Ferric Chloride disadvantages, the PAC coagulant is recommended as a good alternative for Alum in coagulation process.