The County of DuPage
Wheaton, Illinois
 

Woodridge - Greene Valley Wastewater Facility Pictorial Tour

Clean water is transported to your home, work and school. This water is used for purposes such as washing dishes, washing clothes and bathroom use. When the clean water is used, it becomes contaminated with organic and inorganic material which can not be put directly back into the environment. 
The Woodridge Greene Valley Treatment Plant is designed to clean 12 million gallons per day of wastewater. The treatment plant uses biological and physical processes to clean the wastewater, which will be described during the remainder of this tour. Did you know a drop of water leaving your house can be cleaned and put back into the river within 24 hours?
 
 The wastewater is collected by a series of underground pipes which are connected to the wastewater treatment plant. Think of how many pipes are needed to transport your wastewater to the treatment plant.
 Once the wastewater enters the plant, the large materials such as plastics and other debris is removed by mechanical bar screens. This material is then compacted and taken to the landfill for disposal.
 The wastewater is then pumped into these aeration tanks, which contain aerobic microorganisms. We provide ideal conditions for the organisms, by pumping air into the bottom of the tank and mixing the microorganisms with the wastewater. The microorganisms consume (eat) the contaminants (their food) in the wastewater and produce carbon dioxide, clean water and more microorganisms. As the air rises to the top of the tank, the organisms use it to breath, much the same as we do.
 As the organisms and clean wastewater flow from the aeration tanks, they must be separated, which is done at these final settling tanks. The heavier organisms settle to the bottom of these tanks, are collected, and pumped back into the front of the aeration tanks. The clean water flows over the weirs around the parameter of the tank into the next biological process.
 Close-up of Weirs.
 Although most of the contaminants have been removed from the wastewater at this point, there are some nutrients (ammonia nitrogen) which is left in the wastewater and cannot be discharged into the river. The removal of these nutrients is done by trickling the water over media which has a lot of surface area. The microorganisms in this process grow on the surface area of the media and remove the nutrients from the wastewater as it passes by them. These microorganisms grow and will eventually fall off the media.
 Inside the Nitrification Towers
 The wastewater is gathered at the bottom of the towers and pumped s through these filters so any of the organisms which have fallen off the media can be removed. This is a physical process which filters the wastewater through a 30 inch bed of sand and will automatically backwash when the sand becomes plugged.
 Now the contaminants and nutrients have been removed and the wastewater is ready to be put back into the environment. However, before we discharge the clean water to the river, we disinfect using chlorine in these contact tanks which will kill any remaining bacteria.

 
The clean water is discharged into the East Branch of the DuPage River.
You may have thought we were done with our tour, but there is a second product that leaves the treatment plant. This material is called bio-solids. In our main biological process (aeration tanks), we have to control the amount of microorganisms. There is only a certain amount of contaminants (food) in the raw wastewater coming into the plant. If we have too many microorganisms there will not be enough food, and they will starve. If we have too many microorganisms they will not consume all the contaminants (food) and the excess will go to the river. Therefore we have to remove excess microorganisms (biomass) out of the system every day.
 
 The excess microorganisms are pumped to this thickening machine. A small amount of chemical called polymer is added to the solution of microorganisms (biomass). Excess water is removed and the excess biomass is pumped to the next biological process.
 The thickened biomass is pumped to these anaerobic digesters where a different culture of microorganisms (anaerobic) reduce and liquefy the solids and produce methane gas.
 This digested biosolids is pumped to this dewatering equipment. A small amount of polymer is added and water is squeezed out of the digested biosolids to form a mud-like substance which is rich in nitrogen, potassium, and phosphorus. The biosolids are taken to a farm and applied to land as a fertilizer.
 The methane produced in the anaerobic digester is collected and used as fuel to operate this engine generator which produces electricity to operate the Woodridge Greene Valley Treatment Plant.
Thank you for taking this tour. If you would like more technical data you can contact the treatment plant at (630) 985-7400