The kinetics of acrylamide polymerization in an aqueous solution of aluminum pentahydroxochloride representing a disperse system with polycharged aluminum aquahydroco-complexes as the main element was studied. The obtained reagent has a high efficiency in the separation of dispersed systems. The flocculation of activated sludge by polyelectrolyte copolymers based on poly-1,2-dimethyl-5-vinyl-pyridinium methyl sulfate was studied. The influence of flocculants on particle size distribution of activated sludge was studied by the method of optical microscopy and it was shown that the use of copolymers allows to increase the efficiency of dewatering and leads to the formation of strong floccules.