Expression characteristics of polyelectrolyte flocculated sludges

This work investigates how polyelectrolyte flocculation affects the dewater ing efficiency of activated sludge and ball clay slurry. Although the activ ated sludge is much more difficult to dewater than the clay slurry, polyele ctrolyte flocculation markedly enhances the dewatering efficiency of both s ludges, with the maximum improvement occurring at the charge neutralization point. Flocculation yields a stiff cake structure and transforms the major dewatering mechanisms from primary to secondary consolidation. The creepin g of particles in the sludge is enhanced since the presence of flocculant m olecules causes moisture to be expelled from the solid surface. This moistu re loss reduces the total consolidation time and diminishes the tertiary co nsolidation stage in the activated sludge, which is advantageous to dewater ing.