Application of Polyelectrolyte in Turbidity Removal from Surface Water

Abstract

One of the most important treatment processes in surface water treatment plants is coagulation. Surface waters such as rivers and lakes contain suspended particles and turbidity. With the aid of coagulants, and by flocculation process, followed by sedimentation and filtration, these impurities can be removed from raw waters these days, besides conventional chemicals such as Alum and Ferric chloride, polymers are getting common. Polymers can be used as pretreatment and filter aids chemicals, also. There are some advantages in the usage of polymers, such as; higher sedimentation rate, lower price, better finished water quality, lower sludge volume produced, and a better sludge quality with respect to mineral coagulants. Of course some disadvantages are related to the polymers such as the monomers and residues in finished water which may be a health hazard. In this research, four different polymers for turbidity removal from raw waters were investigated. Raw water with turbidities of 200, 500, 700 and 1000 FTU were treated with optimum polymer dosage. The results showed that, polymers with small dosage can be used for water purification. In this regard it was found that Magnafloc LT27 has lowest dosage and better floc strength with respect to others.