AWWA WQTC60669

This paper discusses an effort by United Water New York (UWNY) to design/build the first high rate dissolved air flotation (DAF) system in the United States at its Lake DeForest Water Treatment Plant (LDF WTP). The reasons for the upgrade included: increase plant capacity from 10 mgd to 20 mgd;improve algae removal;capability for pH adjustment prior to coagulant addition (CO₂ was selected);improve filtered performance (lower turbidities and longer filter run times); and,lower disinfection byproducts (DBPs). LDF is the largest reservoir in a chain of reservoirs that comprise the HackensackRiver Watershed. It is a eutrophic lake that receives runoff from suburban fertilizedlawns, septic systems and inputs from streams and smaller lakes that are also eutrophic.Typical water quality ranges in LDF:Algae - up to 5,000 counts;TOC - 4 to 6 mg/L;color - up to 50+ units; and,low turbidity - 3 to 8 ntu.In addition to these treatment challenges, UWNY also needed to maximize microbialremoval/inactivation and minimize DBPs. Major improvements included: CO₂ feed system for pre-coagulation pH adjustment;48-inch in-line static mixer for improved chemical mixing;DAF Pretreatment - hydraulic flocculation;high-rate DAF system;supersaturated air addition;solids separation/DAF Float;residuals wasting/DAF effluent;AquaDAF recycle stream; and,6,000 sf pre-engineered building designed to match existing structures.The total cost for these improvements was $9 million. LDF overall performance is discussed along with chemical optimization, copper sulfate treatment event, aluminum breakthrough, and high filter turbidities. Includes table, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

12

File Size:

1 file , 5.3 MB