Abdollah Dargahi - Instructor of Environmental Health Engineering Department, Khalkhal of Medical Science School, Ardabil Universityof Medical Science, Ardabil, Iran
Masoud Moradi - Member of Environmental Epidemiology research center of Kermanshah University of Medical Sciences and Ph.Dstudent of Environmental Health Engineering Department, Public Health School, Iran University of Medical Science,Tehran, Iran.
Mohammad Taghi Savadpour - Instructor of Environmental Health Engineering Department, Khalkhal of Medical Science School, Ardabil Universityof Medical Science, Ardabil, Iran
Kiomars Sharafi - Instructor of Environmental Health Engineering Department, Kermanshah University of Medical Sciences and Ph.D student of Environmental Health Engineering Department, Public Health School, TehranUniversity of Medical Science, Tehran, Iran

Background & Aims of the Study: Colloidal impurities are one of the naturalcontaminants in surface water that cause turbidity and color. Turbidity in spite ofcreate undesirable appearance, can be a haven for disinfection of microorganisms.This study aimed to evaluate the effectiveness of various coagulants in removingaverage turbidity of water and also their impact on the electrical conductivity andalkalinity.Materials & Methods: The study was conducted as tentative - interfere researchin a laboratory scale. Experiments were carried out based on various parametersincluding different turbidity (50,100 and 200 NTU) and different concentrations ofcoagulants (5, 10, 15, 20, 25 and 30 mg/L). Supernatant of samples were takenafter Jar test to measuring of turbidity, conductivity and alkalinity. The settlingcharacteristics of the floc were record by observing as descriptive terms such aspoor, fair, good and excellent.Results: Results showed that all coagulants materials in whole used levels be ableto completely remove of the initial turbidity (with the exception of Ferrous sulfatecoagulant). On the other hand, with increasing concentrations of coagulants, theelectrical conductivity increased and alkalinity decreased. Also, the highest andthe lowest increase of electrical conductivity and TDS obtained in ferric chlorideand poly aluminum chloride coagulants respectively. Conclusions: The result showed that poly aluminum chloride was best coagulant for turbidity removal and in spite of fine floc, sedimentation rate is good.

CoagulantTurbidityElectrical conductivityAlkalinityDrinking water