The clarifier is a type of sedimentation basin
in which the heavier solids sink to the bottom and the lighter materials
float to the surface. Grease and other scum are skimmed off the
surface of the clarifier and are removed. Sludge settles to the bottom
and is sent to waste. The clear effluent flows out of the clarifier
and continues with the treatment process.
A clarifier can be placed at two stages
in the treatment process. The clarifier shown above is a secondary
clarifier which treats wastewater flowing from the aeration basin, oxidation
ditch, trickling filter, or other type of biological treatment.
Clarifiers are also found earlier in the treatment process,
directly after the grit chamber and comminutor. These clarifiers are
known as primary clarifiers and are similar in design to secondary