How do we do it?
The original plant at the Utilities Services Glade Road Complex was put into operation in 1974 and was designed to treat 10 million gallons per day (mgd) of wastewater. Modifications increased the treatment capacity by 2 mgd in the mid-1980. A late 1980’s expansion program provided 17.5 mgd of treatment capacity to meet demands expected beyond the year 2020. New buildings and structures were designed and constructed to blend with the surroundings. Included in the improvements were an administration building housing an up-to-date laboratory and a computerized monitoring and control suite, as well as offices and training areas.
The grounds of the plant include open, landscaped spaces in keeping with the community's emphasis on a park-like atmosphere. Further complying with objectives to promote preservation of natural resources, the plant was designed to provide reclaimed water for irrigation at the Utilities Complex. This has been expanded in Project IRIS.
Designed to effectively and efficiently help control water pollution in an environmentally sound manner, the plant uses the conventional Activated Sludge Treatment Process with primary clarification.
Primary Clarification: Wastewater flowing into the plant passes through automatic bar screens that retain materials above 1/4-inch diameter. Grit is removed in two forced vortex type grit collectors and ultimately disposed of in a landfill. Two 100-foot diameter domed primary clarifiers remove and dispose of settleable organic solids.
Activated Sludge: Still containing organic substances that must be removed before discharge, the wastewater passes through three aeration "trains", each "train" consisting of three basins. These trains contain large concentrations of microorganisms- called activated sludge - that feed on the organic matter in the wastewater. As these microorganisms require oxygen to grow, air is introduced into the wastewater.
The activated sludge and wastewater then flows to three 110-foot diameter and two 105-foot diameter secondary clarifiers where the sludge settles. The sludge is removed, and a variable percentage is returned to the aeration trains to act as a catalyst for that process.
The effluent, with 95 percent of the biochemical oxygen demand and suspended solids removed, is disinfected through chlorination and is then pumped through a five-mile-long outfall terminating about 5,000 feet offshore in the Atlantic Ocean at a depth of 90 feet.
Sludge consists of the solids that have been separated from the wastewater in the treatment processes. It must be treated and dewatered prior to disposal. The waste activated sludge, which has settled in the bottom of the secondary clarifiers, is pumped to the gravity belt thickeners, where 75 percent of the water in the sludge is removed. This thickened sludge is then pumped to two of three 80-foot diameter primary digesters and one 80-foot diameter secondary digester. Sludge that has settled in the bottom of the primary clarifiers is pumped directly to the digesters.
In the digesters, anaerobic bacteria are used to break down the organic solids. Methane gas and carbon dioxide are by-products of this process, and the methane gas is used to heat the digesters. Three belt filter presses dewater the digested sludge prior to landspreading.