Although the wastewater treatment process is a complex arrangement of pipes, pumps and tanks, it is designed to do two basic things. First, it speeds up the natural process by which water purifies itself. Second, it removes the contaminants that may harm the environment. Essentially the treatment process harnesses and enhances -- in a relatively short amount of time -- the cleansing process that would occur naturally in a lake or stream.
Treatment is accomplished through a three-stage process: Primary, Secondary and Tertiary. In Primary Treatment, water passes through screens to remove plastics, wood, sand, grit, floating objects and other heavy solids.
During Secondary Treatment, any remaining solid material in the water is removed by supplying air (O2) in an Aeration Tank. This stimulates the growth of helpful microorganisms, which consume organic matter in the wastewater. The Nutrient Removal Process uses bacteria to remove nutrients (like Nitrogen and Phosphorus) that are harmful to aquatic life. The water then moves to a Secondary Clarification Tank that allows the microorganisms and solid wastes to form clumps and settle to the bottom. Some of this residue is mixed with air again and reused in the Aeration Tank.
In Tertiary Treatment, the water passes through a deep-bed sand filter before it is disinfected as is passes through an Ultraviolet Disinfection System. The light inactivates bacteria in the water so it cannot reproduce. The purified water is then returned to the aquatic environment of the Tar River.