The Corporation of the Town of Cochrane

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  1. Wastewater is collected and enters the treatment facility through the sewer system.
  1. Metal bars collect large debris such as rags, wood, plastics, etc.
  1. In the Comminution process, a large grinder further breaks up debris into small pieces.
  1. The Grit Removal chamber slows down the incoming wastewater (influent) to allow dense, inorganic material to settle on the bottom. Grit is removed on a scheduled basis.
  1. Wastewater is drawn from the top of the Grit Removal chamber and sent to the large Aeration tanks. These tanks mix the wastewater with oxygen (which causes bubbles) to support bacteria that devour organic waste. When the bacteria interact with waste, it creates a slimy residue (sludge).
  1. The wastewater is drawn from the top of the Aeration tanks to the Clarifier or Final Settling tank. By this point the water is already quite clear.
  1. In the Clarifier, suspended particles and any remaining sludge (clumped sewage) settle to the bottom. The sludge is then drawn from the bottom of the tank and part of it is sent to Dewatering tanks while the other part is returned to the Aeration tank. The sludge that is returned to the Aeration tank is called Activated Sludge as it contains the bacteria that devour organic waste.
  1. The cleanest water is drawn from the surface of the Clarifier and is disinfected in the Chlorination Chamber prior to being returned to the environment.
  1. A further separation of water and sludge occurs in the Dewatering Tanks. Clear water, which is drawn from the surface, is returned to the Aeration tank. The sludge becomes more and more dense and is then sent to the Holding tank until disposal.
  1. The concentrated sludge, or bio-solid waste in the Holding tank is taken away for disposal.

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Last modified: 11/03/10 Water / Sewer Services