Application of Coagulant Polymer and Polymer Blends to Enhance Settled Water Quality: DWSD's Full-scale Experience

摘要

Following conclusions were reached based on the results from Full-scale evaluation of polymer aids in improving coagulation/flocculation and filtration performances. 1. The use of cationic polymer in combination with alum as a primary coagulant would enhance coagulation/flocculation process, increase settled water pH, and reduce sludge volumes at the Northeast WTP. 2. If a continuous application of cationic polymer aid is desired through all seasons than a cost comparison should be performed to determine the cost effective application of cationic polymer either through an alum-polymer blend supplied by General Chemical or a separate cationic polymer addition system. The cost analysis should include cost for necessary equipment (storage tanks, polymer application units etc). 3. For an intermittent use of polymer aid (seasonal), a cationic polymer dose between 0.4 to 0.6 mg/l would be able to mitigate the seasonal turbidity spikes in combination with alum as the primary coagulant. 4. The use of small dose of anionic polymer as a filter aid for the initial one hour of filter operation would increase filter run time and reduce filter backwash water volumes at Northeast WTP. 5. Anionic filter aid polymer should be added to filter influent pipe with a dose ranging from 0.005 to 0.007 mg/l as polymer. The filter aid polymer should be prepared using an AnCat polymer system or equivalent. The diluted polymer should be stored in a small tank and feed using peristaltic pump.