Centrifugation

Centrifuges are used to thicken and dewater waste activated sludges. They involve the settling of sludge particles under the influence of centrifugal forces. Two basic types of centrifuges are the solid bowl and the imperforate basket.

(a) The solid bowl centrifuge consists of a long, horizontally mounted bowl, tapered at one end. Sludge is introduced continuously and the solids concentrate on the periphery. This gives solids concentration between 3-6%.

(b) The imperforate basket centrifuge consists of a vertically mounted spinning bowl, operating on a batch basis. The solids accumulate against the wall of the bowl and the liquid is decanted. This gives solids concentration between 8-10%.