Course: BFM 203 Water Treatment and Control

Lecture

(3/8)

Upflow Clarification

Use of an upflow clarifier causes water to slow flow up through a blanket. No separate sedimentation step is needed. The theory is that heavier particles will remain in the lower portion of the clarifier, assisting in the removal of additional turbidity. Thus, only clarified water will be extracted from the top of the unit. Upset conditions in an upflow clarifier are more difficult to recover from because blanket condition directly affects particle removal rates.

Upflow solids contact clarification units, also known as upflow sludge blanket clarification units, are rectangular or circular clarifiers with a sloped bottom, sludge rakes, waste sump, and effluent weirs that are similar to traditional clarifiers. The influent water is mixed with coagulant and/or softening chemicals and is discharged into the center of the clarifier. It must then flow around the baffle and up through a sludge blanket or slurry. The sludge blanket provides additional clarification, providing clear water above the blanket that flows over the effluent weir. These units are sensitive to changes in flow and temperature. The following diagram illustrates these principles of operating an upflow clarifier.