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Madison-Chatham Joint Meeting

How a treatment plant works

 1.  Screening.  A simple process that removes large materials such as wood, rocks and other items.

2.  Pumping.  Our treatment plant is located on low ground, so much of the wastewater travels via gravity to the plant.  Once in the plant and depending on the topography, most treatment plants have pumps to move the wastewater from one treatment area to another.

3.  Aerating. Bubbling oxygen through the sewage helps release some of the dissolved gases from the water into the air.  It also helps larger 'grit' such as sand, coffee grounds, etc to settle out.

4.  Sedimentation.  Sludge settles out of the wastewater and is pumped out of the sedimentation tank and then processed in a large 'digester' tank.

5.  Removing Scum.  As the sludge settles to the bottom, lighter items such as grease, oils, plastics and soap float to the top.  slow-moving rakes skim the material off the surface.  Thickened scum is pumped into the digesters with the sludge.

6.  Finally, the wastewater is treated, often with filtration and/or clorine to remove bacteria, odors and other items.  The water is now clean and discharged into a local river.

R. Solid Waste Digester.  Solids are kept in a large, heated tank for many days.  This tank acts like a stomach and 'disgests' the material using bacteria.  Digesting the material reduces the volume and odor and produces Methane Gas which can be used to help heat the digester tank.  The finished material is then sent to a landfill.

For more information about how our treatment plant works, please visit the US Geological Survey website at http://ga.water.usgs.gov/edu/wwvisit.html.