Evaluation of performance of different aluminium-based coagulants and aids in river water clarification

Abstract

Coagulation and fl occulation is one of the most effective, economic and convenient method for raw water clarifi cation. In recent times, different hydrolysing coagulants, particularly aluminium-based ones are in wide use. In the present study, different aluminium-based salts, polymer and coagulant aid were used to observe their effectiveness as well as side effects, if any. Turbidity was the prime criterion for clarifi cation of the raw water; however, the potentially hazardous residual aluminium was also given due importance. Poly-aluminium chloride (PACl) enhanced the performance of the potash alum when used in tandem, whereas bentonite powder used as coagulant aid proved ineffective in improving the performance of the potash alum with respect to the removal of the turbidity. PACl when used alone or in tandem with potash alum showed character signifi cantly different from aluminium-based salts only, with respect to the criterion of residual aluminium. © 2014 WIT Press.