|HRSD - King William
||Tidewater Regional Office
Brief Project Description
Grantee: Hampton Roads Sanitation District (HRSD) - King William Treatment Plant
Grant: #440-S-10-01 (King William Treatment Plant Expansion-Phase I)
HRSD owns and operates the King William Treatment Plant (KWTP) in King William County near Central Garage, Virginia. Until mid-2007 this facility consisted of a secondary treatment system (activated sludge), with a design flow of 25,000 gallons per day (gpd). Due to its inability to consistently meet VPDES effluent limits, however, the facility ceased to discharge in 2000 and wastewater flows were “pumped and hauled” to other facilities for treatment. In May 2007, the plant was upgraded to comply with stricter nutrient requirements and expanded to accommodate population growth in the service area.
Under new nutrient discharge control regulations for the Chesapeake Bay and its tributaries, HRSD has received a combined, “bubble” waste load allocation for nitrogen and phosphorus for its four treatment plants discharging within the York River watershed. Although it represents a small flow, providing nutrient removal at the KWTP is a key element for meeting HRSD’s aggregate waste load allocation, shared with the York, West Point, and Mathews Courthouse facilities, for the York River and improving local water quality while meeting the growth needs of the County.
In 2007, under a plan referenced as King William Treatment Plant Expansion-Phase I, HRSD upgraded the existing secondary treatment process to an enhanced nutrient removal (ENR) system designed for an annual average total nitrogen effluent concentration of 4.0 mg/l at a design flow of 100,000 gpd. This involved the installation of two 50,000 gpd membrane bioreactor trains, each of which integrate rotary drum screens, four biological process tanks (two swing zone tanks, one aerobic tank, one anoxic tank), membrane modules, chemical feed, and UV disinfection and instrumentation in enclosed, pre-fabricated carbon steel units. The existing mechanical bar screen and outfall were retained in the new facility. The existing aeration tank was converted to a flow equalization tank. Solids are now stored in the previous equalization tank and then “pump and hauled” to the West Point Treatment Plant for final disposal.
The self-contained membrane bioreactor (MBR) units are well-suited for small flow applications such as KWTP since they can be added in modular fashion as needed. HRSD has adequate space at the site to expand by another 100,000 gpd in a Phase II project when required at a future date.