en تخصصي Special Original articles <p dir="ltr" style="text-align: justify; "><strong><em><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Introduction:</span></span></em></strong><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> Colloidal materials and suspended solids cause turbidity in water. To remove turbidity, clarification method is used that includes processes of coagulation, flocculation, and sedimentation. Due to the long duration of coagulation process, coagulant aids are applied. Despite the favorable efficiency of synthetic polyelectrolytes as a coagulant aid, due to their harmful effects on human health, in this process, natural organic polymers are used instead.</span></span><br> <strong><em><span style="font-family:times new roman,serif;">Materials and Methods:</span></em></strong><span style="font-family:times new roman,serif;"> In this research, the use of tragacanth as a natural organic coagulant aid </span><span style="font-family:times new roman,serif;">was studied </span><span style="font-family:times new roman,serif;">instead of synthetic polymers in water turbidity removal along with alum and poly aluminum chloride. To compare the experiments with natural conditions, Karun River water </span><span style="font-family:times new roman,serif;">was</span><span style="font-family:times new roman,serif;"> analyzed. To complete these studies, the effects of several factors such as tragacanth concentration, the concentration of alum and poly aluminum chloride, and pH changes in average and low turbidity </span><span style="font-family:times new roman,serif;">were</span><span style="font-family:times new roman,serif;"> investigated. Optimum pH for turbidity removal was determined by jar testing.</span><br> <strong><span style="font-family:times new roman,serif;">Results</span></strong><span style="font-family:times new roman,serif;">: The results showed that the best pH to remove turbidity </span><span style="font-family:times new roman,serif;">was from</span><span style="font-family:times new roman,serif;"> 5.5 to 7, with the efficiency of 97.3%. At </span><span style="font-family:times new roman,serif;">p</span><span style="font-family:times new roman,serif;">H = 6 and at the concentration of 30 mg/L, poly ammonium chloride ha</span><span style="font-family:times new roman,serif;">d</span><span style="font-family:times new roman,serif;"> maximum efficiency (90%). Using tragacan</span><span style="font-family:times new roman,serif;">th</span> <span style="font-family:times new roman,serif;">with</span><span style="font-family:times new roman,serif;"> concentrations of 1 and 4 mg/L along with alum at a concentration of 40 mg/L</span> <span style="font-family:times new roman,serif;">leads to turbidity removal of 81.75%.</span><br> <strong><span style="font-family:times new roman,serif;"><span style="font-size:11.0pt;">Conclusion</span></span></strong><span style="font-family:times new roman,serif;"><span style="font-size:11.0pt;">: Using 2 and 4 mg/L of tragacanth, a significant removal efficiency is achieved in low and average turbidity. pH = 7 leads to the most efficient use of tragacanth coagulant aid.</span></span></p> Aluminium Compounds,Tragacanth,Coagulants,Turbidity Removal. 1 8 http://jehsd.ssu.ac.ir/browse.php?a_code=A-10-1-1&slc_lang=en&sid=1 Majid Farhadi No Environmental Health Engineering, School of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Afshin Takdastan Takdastan2000@yahoo.com Yes Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Roghayeh Baghbany No School of health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.