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 (CO<sub>2</sub> 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 Hackensack
River Watershed. It is a eutrophic lake that receives runoff from suburban fertilized
lawns, 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 microbial
removal/inactivation and minimize DBPs. Major improvements included: CO<sub>2</sub> 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.
| Edition : | Vol. - No. |
| File Size : | 1
file |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 11/15/2004 |
