ABSTRACT
Polyelectrolytes improve the solids capture of a centrifuge and increase the capacity of drying beds, vacuum filters, and filter presses. Polyelectrolytes have two characteristics important for liquid-solids separation, whether in the initial stages such as clarification or in the later stages of sludge thickening and dewatering: electrical charge and molecular weight, as manifested in molecular length and structure. In dewatering operations, the molecular weight of the polyelectrolyte is a more important consideration than encountered in the earlier liquid-solids separation steps of clarification and thickening. The chemical conditioning required for the particular type of system will vary from device to device. It is necessary that this be obtained in order to have efficient liquid-solids separation. The most economical system of dewatering will be one in which the equipment and conditioning systems chosen will be those which deliver the specific degree of separation at the lowest cost.
