Expression characteristics of polyelectrolyte flocculated sludges

This work investigates how polyelectrolyte flocculation affects the dewatering efficiency of activated sludge and ball clay slurry. Although the activated sludge is much more difficult to dewater than the clay slurry, polyelectrolyte flocculation markedly enhances the dewatering efficiency of both sludges, 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 creeping of particles in the sludge is enhanced since the presence of flocculant molecules causes moisture to be expelled from the solid surface. This moisture loss reduces the total consolidation time and diminishes the tertiary consolidation stage in the activated sludge, which is advantageous to dewatering.