Turbidity and Some Heavy Metals Removal Efficacy by Poly Aluminium Chloride (PAC) Coagulant in the Presence of Bentonite and Polyelectrolyte Coagulant Aid(Case Study: Isfahan Babashikhali Water Treatment Plant)

One of the important steps in the process of removing water turbidity is the use of coagulants. Amongst the most applied materials is poly aluminum chloride (PAC) which is used to precipitate colloidal particles. The use of this compound, which contains Aluminum, in the coagulation causes some residual aluminum in the water. Natural and synthetic coagulants aid can be used to reduce the effects of overuse of poly aluminum chloride. In this study, the effect of bentonite and polyelectrolyte coagulant aid in the turbidity removal process of Babasheikhali water treatment plant is investigated. The results showed that optimum pH for turbidity removal was 8 and the optimal concentration of poly aluminum chloride at the optimum pH was 10 mg/L. In the presence of bentonite, the optimal PAC concentration decreased to 4mg/L and the turbidity removal efficiency increased to 92%. The results also showed that the combination of PAC and polyelectrolyte together can be used to reduce the concentration of heavy metals in the incoming water. Therefore, bentonite and polyelectrolyte coagulants aid can be used as a suitable option along with poly aluminum chloride to remove turbidity from the water treatment plant.