Wastewater - Secondary Treatment: Clarifier


Michigan Environmental Education Curriculum
Wastewater Treatment

It then remains to separate out the microorganisms (activated sludge) so that just clean water is left. This is done in a secondary clarifier which operates in the same manner as the primary clarifier described previously. Some of the solids collected in the secondary clarifier (return activated sludge) are sent back to the aeration tank to treat more wastewater and the excess (waste activated sludge) is pumped to another location in the plant for further treatment. The clean water that flows out the top of the clarifier is sent along for disinfection.

Wastewater from Aeration Tank

Wastewater leaving the activated sludge aeration tank on its way to the secondary clarifier

Secondary Clarifier

Secondary clarifier covered to prevent icing

Secondary Clarifier Weir

Wastewater leaving the secondary clarifier

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