investigating the coagulation efficiency of paci in reduction of water turibidty in shahrchay river in city of orumieh and its health effects

background: today with population growing, surface water is one of the most important water resources used for domestic and industrial consumptions. in order to purify the surface water, coagulants materials are used. the purpose of this study was to assess the possibility of using poly aluminum chloride (pacl) in water refinery number 1 in city of orumieh and investigating its health effects. methods: in this cross - sectional study, samples were taken in spring and then various concentrations of pacl coagulants material were added to the samples by using the jar test device to obtain the most suitable concentration. also in this experiment the values of ph, turbidity, alkalinity and residual aluminum were measured. findings: based on the findings of the experiments the concentration of residual aluminum in the range of 5 to 20 mg/lit coagulant consumption was 0.29 mg/lit and also in the range of 20 to 40 mg/lit coagulant consumption it was 0.5 mg/lit. the efficiency of turbidity removal within less than 100 ntu was approximately 78% to 98% and in the range of over 100 ntu, more than 99%, thus by increasing the turbidity, removal is more effective. conclusion: according to the required low concentration of pacl and consequently less sludge production, low coagulant consumption and small reduction of ph, pacl application is economical; and also in density of less than 20 mg/lit, the residual aluminum was lower but more residual aluminum was produced in over 20 mg/lit concentration which is inappropriate in terms of its association with alzheimer's disease and health issues.