The present paper outlines the impact of hydrolysis occurring in DMAEA-Q type polymers in the dewatering facilities of municipal wastewater treatment plants. Laboratory studies of polymer hydrolysis kinetics were combined with full-scale dewatering experiments to investigate the influence of polymer charge loss on polymer consumption and cake dry matter yields. The results indicate that prolonged polymer storage leads to important charge loss effects, resulting in increased dosage requirements for satisfactory dewatering performance. Fortunately, charge loss effects due to hydrolysis upon polymer storage could be minimized by acidifying the polymer batches. Furthermore, cake dry matter contents obtained from dewatering tests with freshly prepared polymer batches suggested that acidification of the polymer batch also had a beneficial effect on the conditioning efficiency of the polymer solution. The results from this study thus stress the influence of pH on the shelf life and efficiency of polymer solutions in wastewater treatment plants. As a consequence, polymer preparation and storage procedures should be adapted to the polymer consumption pattern and pH of the medium used for polymer batch production.
Keywords: cationic polyelectrolytes, dewatering, dry matter content, polymer dosing