Where Wastewater Comes From
Each residence served by the Utilities Division, on average, produces 375 gallons of wastewater or sewage every day, which amounts to more than 30 million gallons of wastewater processed daily when combined with the Division’s more than 80,000 other customers. Business and industrial users produce more than five million gallons of wastewater, bringing the total wastewater handled each day to more than 35 million gallons. Our current wastewater processing capacity is 51 million gallons daily.
Wastewater is moved from its originating source, whether residential or business/industrial users, to two strategically located processing facilities through a network of 1,439 miles of sewer mains and 52 wastewater pump stations.
How Wastewater is Treated
Wastewater treatment begins with the removal of debris through bar screens and a Grit Chamber, where the debris settles to the bottom of the chamber and is regularly removed. From there the wastewater is passed to the Primary Clarifier, where other solid material settles to the bottom as sludge and is also regularly removed along with scum which forms Primary Clarifiers’ surface. Once these materials are removed, the wastewater enters the Activated Sludge Basin, or a set of chambers where microbes remove contaminants. This process is facilitated by the pumping of air into the chambers. Once the contaminants have been removed, the wastewater moves to the Final Clarifier, where the water is separated from any remaining heavier than water material.
Once all solid matter has been removed, the water moves to a Chlorine Chamber, where chlorine is used to kill bacteria. The water then filters through a Contact Basin that holds the water for about 90 minutes while the chlorine disinfects the water. Once treatment is completed, which typically requires 24 hours, the water is returned to the Yadkin River at Muddy Creek’s confluence with the river.
Wastewater Treatment Facilities
The Winston-Salem/Forsyth County Utilities Division operates two wastewater treatment facilities, although many residents refer to them as “sewer plants.” The term “sewer” is most commonly associated with human waste from homes and restaurants. In addition to this waste stream, the treatment facilities must treat wastewater generated by a variety of industries in Forsyth County. Currently, approximately 12 percent of the wastewater treated at these facilities originates from an industrial process.
The Archie Elledge Wastewater Treatment Plant is located on the southwestern side of Winston-Salem and began operating in 1958, with the capacity to treat 18 million gallons of wastewater per day. Since that time, the Elledge Plant’s treatment capacity has grown to 30 million gallons per day (MGD). After the thorough wastewater treatment process described above, the Elledge Plant releases the treated, environmentally compatible water into Salem Creek, the receiving stream.
The Muddy Creek Wastewater Treatment Plant is located on the southern border of Forsyth County and is permitted for 21 million gallons per day of residential and industrial wastewater. The plant discharges its treated effluent into the Yadkin River.
Maintenance and Warehouse
The Maintenance and Warehouse units provide the staff expertise and replacement parts for the repairs necessary to keep the treatment plants and wastewater pumping stations operating properly. The maintenance crews rely on the warehouse to provide them the spare parts, tools, and supplies necessary to perform corrective and preventative maintenance for the treatment plants and the pumping stations. The maintenance staff includes an electrical and instrumentation maintenance crew that repairs and maintains the complex electrical and instrumentation systems.
Biosolids Disposal Program
This program disposes of wastewater treatment plant biosolids in a manner that is considered beneficial reuse. The liquid wastewater sludge is applied to farmland at agronomic rates that provide valuable nutrients to the farmland but is controlled so that operators and land are protected from over fertilizing or any harmful constituents that may be present in the sludge.
What Happens to Sludge
An expected byproduct of wastewater treatment is sludge, or the material that is removed as a part of the treatment process. Once removed, sludge goes through a two-step digester process that ferments the organic part of the sludge (which is much like vinegar) into products like methane carbon dioxide and water. Through this process, the sludge is stabilized to meet the Environmental Protection Agency’s 503 rules and can be land applied as a fertilizer. The sludge is then dewatered to approximately 20 percent solid and is either recycled as fertilizer for nonconsumable crops or is transported to the Landfill. Approximately 65 percent of the sludge processed becomes fertilizer. The remaining 35 percent, which is not presently usable as fertilizer, is transported to the Landfill.
What You Can Do to Help Avoid Sewage Spills
Our wastewater collection and treatment system is designed to handle three things: used water, human body waste, and toilet paper. It is very important to keep all foreign materials, such as grease and other household debris from entering the system because they can cause blockages that lead to sewage spills.
- Don’t pour grease, fats, and oils from cooking down the drain. Collect the grease in a container and dispose of it in the garbage. Your refrigerator is a good place to store the grease until disposal because its lower temperature will solidify the liquid.
- Don’t use the toilet as a wastebasket. Place a wastebasket in each bathroom for the disposal of trash, disposable diapers, and personal hygiene or contraceptive products.
- Don’t use your food disposal as the catchall for kitchen waste. Food scraps should be moved to a compost pile or place them in the garbage.
Meeting our area’s wastewater needs is a shared responsibility of the City of Winston-Salem and Forsyth County. Operating responsibility for the system is a function of the City of Winston-Salem Utilities Division, with governance provided by the City/County Utility Commission, whose members are appointed by the Winston-Salem City Council and the Forsyth County Board of County Commissioners.