Introduction
Wastewater treatment clarifiers, also known as sedimentation tanks, are used in wastewater treatment plants to remove solid materials from the water being processed. The waste water treatment plant at the Arcata Marsh uses two clarifiers, one 26ft diameter tank and one 60ft diameter tank Fig.1.
Description
After passing through the Headworks where large solids, objects and particles are removed, the wastewater moves on the the primary clarifiers. Wastewater enters the clarifier through the influent well Fig.3 in the center of the tank. Once the water enters the tank solids begin to settle out of the water; the denser solids(sludge) settle to the bottom of the tank and less dense solids(scum) and oils float to the surface. The floating scum is skimmed off of the surface by a large rotating arm called the surface skimmer Fig.2. Once collected by the surface skimmer the scum is deposited into the scum trough and is transported to a storage container alongside the clarifier Fig.4. The sludge on the bottom of the tank gets collected by rotating collector arms which moves the sludge to the center of the tank. Once the sludge collects at the bottom of the tank it gets pumped to the digester to be processed and converted into biogas.
Links
References
- Davis, Mackenzie, and Susan Masten. Principles of Environmental Engineering and Science. McGraw Hill: New York, NY 2004.
- http://www.humboldt.edu/~ere_dept/marsh/flow2.html
- http://en.wikipedia.org/wiki/Sewage_treatment#Sedimentation
- http://www.gc3.com/techdb/manual/clartext.htm