ABSTRACT
Sludge thickening is the process used to increase the solids content of sludge by the separation and removal of a portion of the liquid phase from sludge. To illustrate, if waste activated sludge, which is typically pumped from secondary settling tanks with a content of 0.8% solids, can be thickened to a content of 4% solids, then five-fold decrease in sludge volume is achieved. Thickening is generally accomplished by physical means, including gravity settling, flotation, and centrifugation.
