assessment of coagulants efficiency in water treatment of karoun river

background: many kinds of inorganic polymers have been developed, but, amongst them, polyaluminum chloride (pacl) is one of the most common kinds and has become most widely applied.[objectives]the main objective in this research was the evaluation of three coagulants efficiency in the turbidity removal of karoun river water in water treatment plant (wtp) of kute amir in different turbidity ranges of 0 to 20000 ntu.[methods]for evaluation of the three coagulants efficiency (including polyaluminum chloride (pacl), aluminum sulfate (alum) and ferric chloride) a jartest was done for every turbidity range. in this research, coagulant aid (besfloc) was added when samples turbidity were 300 ntu. turbidity of samples were measured by the turbidity meter with the model of hach2100n.[results]according to the results, it was clear that pacl and ferric chloride had the better results in turbidity removal in comparison with alum. considering ferric chloride is cheaper than pacl and alum, wtps prefer to use ferric chloride. economic analysis in wtp of kute amir showed that using ferric chloride achieved less costs in comparison with pacl and alum.[conclusions]considering close and suitable results of ferric chloride and pacl in turbidity removal and more economical efficiency of ferric chloride than pacl, it s recommended to be used from ferric chloride with besfloc when turbidity is under 6500 ntu. in the end, injection of coagulants different doses did not vary ph samples significantly.