Majid Farhadi - Environmental Health Engineering, School of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz,Iran.
Afshin Takdastan - Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Roghayeh Baghbany - School of health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

Introduction: Colloidal materials and suspended solids cause turbidity in water.To remove turbidity, clarification method is used that includes processes ofcoagulation, flocculation, and sedimentation. Due to the long duration ofcoagulation process, coagulant aids are applied. Despite the favorable efficiencyof synthetic polyelectrolytes as a coagulant aid, due to their harmful effects onhuman health, in this process, natural organic polymers are used instead.Materials and Methods: In this research, the use of tragacanth as a naturalorganic coagulant aid was studied instead of synthetic polymers in waterturbidity removal along with alum and poly aluminum chloride. To compare theexperiments with natural conditions, Karun River water was analyzed. Tocomplete these studies, the effects of several factors such as tragacanthconcentration, the concentration of alum and poly aluminum chloride, and pHchanges in average and low turbidity were investigated. Optimum pH forturbidity removal was determined by jar testing.Results: The results showed that the best pH to remove turbidity was from 5.5to 7, with the efficiency of 97.3%. At pH = 6 and at the concentration of 30mg/L, poly ammonium chloride had maximum efficiency (90%). Usingtragacanth with concentrations of 1 and 4 mg/L along with alum at aconcentration of 40 mg/L leads to turbidity removal of 81.75%.Conclusion: Using 2 and 4 mg/L of tragacanth, a significant removal efficiencyis achieved in low and average turbidity. pH = 7 leads to the most efficient useof tragacanth coagulant aid.

Aluminium Compounds,Tragacanth,Coagulants,Turbidity Removal