Forty-two million gallons of wastewater are processed at the Nine Springs Wastewater Treatment Plant every day.  The complex assemblage of tanks, pipes, and equipment at the plant merely copies the way nature would decompose and biodegrade wastewater.

Incoming wastewater flows through fine screens to remove large material and rags.  All of the wastewater passes through 1/4" round holes in the screens.

The wastewater is 99.9% water.  Vortex action is used in the grit chambers to allow sand, gravel, and other inorganic solids to accumulate in the bottom of the tanks.

Wastewater then flows to primary settling tanks where about half of the suspended organic material settles to the bottom.  These settled solids are called primary sludge.  The liquid or primary effluent has now completed primary treatment.  It then enters secondary treatment to be biologically treated.

Primary effluent flows to the aeration tanks where secondary (biological) treatment begins.  Bacteria and microorganisms growing in the aeration tanks remove organic matter by consuming it as food.  As they multiply, they convert the organic matter to body mass.   Air bubbling from the bottom circulates the mixture and gives the aerobic bacteria the oxygen they need to live.

This mixture of wastewater and microorganisms called mixed liquor then flows to the final clarifiers where the microorganisms settle to the bottom.  With most of the solids and organic matter removed, the water leaving the final clarifiers has completed secondary treatment.

In the final step, the treated wastewater or effluent passes through disinfection chambers designed to kill disease-causing bacteria with ultraviolet light.  The ultraviolet light disinfection system at the Nine Springs plant was the largest in the world at the time of its installation in 1986.

In less than 24 hours, the Nine Springs Wastewater Treatment Plant cleans the water so that it may be safely returned to the environment.