Investigating the Efficiency of Natural Coagulant Aid (Tragacanth) with PAC in Removal of Turbidity and Coliform Bacteria from Karoon River Water

Conventional water treatment processes include screening, coagulation, flocculation, sedimentation, filtration and disinfection. Many coagulants are widely used in conventional water treatment processes. These materials can be classified into inorganic and organic coagulants. Many researches on natural coagulants were carried out in recent years. This study evaluates Tragacanth as natural coagulants aids with poly aluminum chloride (PAC) for the removal of turbidity and coliform bacteria from water Karoon River. Tragacanth is a gum that extracted from astragalus. According to results of this study, adding tragacanth as a coagulant aid improved performance of the process and experimental observations showed that by applying tragacanth as coagulant aid in optimal conditions, larger flocks are formed compared to PAC applications and the sedimentation rate was higher. In total, this study showed that dose of 0.06 mg/l of tragacanth as a coagulants aid with 15 mg/l of PAC coagulant in high turbidity (480-500 NTU) has the best performance in reducing turbidity and total coliform.