ABSTRACT
In water and wastewater treatment plants, sludge is transferred from point to point by pumping the sludge in conditions ranging from a watery sludge or scum to a thick sludge. Pumping may be intermittent, as in the case of raw sludge from settling tank to the digester, or continuous as in the return of the activated sludge to the aeration tank. Effective sludge pumping depends on properly matching the pump, solids characteristics, and actual system head requirements. The efficiency of a sludge pump is considered subordinate to dependable, satisfactory and trouble-free operation. Fresh plainsedimentation solids are especially diverse in their composition; digested solids and activated sludges less so; alum and iron flocs least of all. In order to determine the operating speed and power requirement for a centrifugal pump handling sludge, system curves need to be computed for the most dense sludge anticipated, for average conditions, and for water.
