Platinum Award for Cedar Creek WPCP Thickeners Upgrade
(NEW YORK, NY – April 15, 2011) – The American Council of Engineering Companies – New York has bestowed the 2011 Platinum Award on the upgrade of gravity belt thickeners at the 76-mgd Cedar Creek Water Pollution Control Plant, located in Wantagh (NY) and operated by the Nassau County Department of Public Works.
This project required replacement of the original, aging sludge thickening system and outdated equipment to optimize efficiency. Sludge thickening is a critical step in the treatment process, allowing solids to be effectively removed from the influent wastewater. In its original configuration, the Cedar Creek sludge thickening system utilized a dissolved air flotation (DAF) process, in which tiny air bubbles were used to float solids to the top of eight DAF tanks within a dedicated sludge thickening building.
Using in-depth analysis of cost, performance, and overall impact on the treatment plant’s performance, Hazen and Sawyer determined that another technology, gravity belt thickeners (GBTs), would be more effective and efficient than in-kind replacement of the DAF system. GBTs utilize motor-driven belts to drain water from and thicken sludge.
Benefits for both the client and the public include:
- Maximized use of existing space. The space-saving design utilizes only half of the existing space, repurposing four of the eight DAF tanks and leaving the client with additional space for storage or other future needs in the area currently occupied by the remaining four decommissioned DAF tanks.
- Reduced energy consumption and greater performance efficiency. A 50% thicker sludge means greater efficiency in the solids treatment train, with reduced sludge volume leaving the thickening facility and the site. This results in reduced sludge heating requirements, increased digester and dewatering capacity, increased storage capacity, and reduced odor control chemical costs.
- Decreased plant carbon footprint by 30%.
- Cleaner air for users of adjacent Cedar Creek Park. Due to a more efficient thickening process, fewer sludge-hauling trucks enter and exit the plant, which is accessible only through the park.
- Significantly lower annual operational costs for solids treatment, by about $1.2 million.
The new GBT system cleverly reuses a portion of the existing space that had previously housed the DAF system. The GBTs (along with chemical storage and new access walkways) were installed atop concrete slab over the decommissioned DAF tanks. The interiors of four of the old tanks were gutted and repurposed to house all necessary piping for the new system. Stairs lead from the operating level down to the gallery within the tanks for ease of operator access.
Since our founding in 1951, Hazen and Sawyer has focused on two things: providing safe drinking water and controlling water pollution. Our range of services encompasses the planning, design, and construction management of water and wastewater-related projects – from clean water treatment, storage, and distribution to wastewater and stormwater collection, treatment, and reuse.