Poly(acrylamide-co-sodium acrylate) Used as a Flocculation Aid Associated with Aluminum Polychloride in the Treatment of Low Turbidity Surface Water by Charge Neutralization

The use of flocculation aids is a common practice in the treatment of urban water supply systems, and synthetic polymers containing polyacrylamide are widely used in this context. The aim of this study was to test the effectiveness of poly(acrylamide-co-sodium acrylate) obtained from the polyacrylonitrile recycling process as a flocculation aid employed in ranges of small and large concentrations. The experiments were performed in jar tests using low turbidity surface water. Two concentrations of polymer were tested: a small concentration ranging from 0 to 2.5 mg L-1, and a large concentration varying from 0 to 125 mg L-1. Zeta potential and pH were measured after the application of the reagents, and turbidity after the jar test experiment. The results indicated that 2 mg L-1 of the polymer as a flocculation aid increased the removal of turbidity. However, the experiments using larger doses of the reagent interfered with the coagulation-flocculation process, probably due to the high final pH level, charge repulsion, or steric hindrance.