Patent ID: 6171505
Filing Date: 2001-01-09
Classification: C02F,Y10S

Abstract:
A method of clarifying and dewatering waste water comprising adding to the waste water an effective amount of a water-soluble cationic polymer dispersion containing at least 25 weight percent polymer solids, wherein the water-soluble cationic polymer dispersion is prepared by polymerizing monomers under free radical forming conditions in an aqueous solution of an anionic salt in the presence of two or more stabilizer polymers, the monomers selected from the group consisting of:(a) at least 5 mole % of a cationic monomer of formula ##STR11##whereinR.sub.1 is selected from the group consisting of H and CH.sub.3 ;R.sub.2 and R.sub.3 are selected from C.sub.1 akyl and C.sub.2 alkyl;A.sub.1 is O;B.sub.1 is C.sub.2 alkyl or C.sub.3 alkyl; andX.sub.1.sup.- is an anionic counterion and(b) a monomer of formula: ##STR12##whereinR.sub.4 is H or CH.sub.3 ;R.sub.5 and R.sub.6 are selected from C.sub.1 alkyl and C.sub.2 alkyl;R.sub.7 is H, C.sub.1 alkyl or C.sub.2 alkyl;B.sub.2 is C.sub.2 alkyl or C.sub.3 alkyl; andX.sub.2.sup.- is an anionic counterion andc) at least 5 mole % of acrylamide or methacrylamide,wherein the stabilizer polymers are cationic polymers that are at least partially soluble in the aqueous solution of the anionic salt, the stabilizer polymers comprising:(a) at least one cationic polymer consisting of diallyldimethylammonium chloride and a monomer of formula ##STR13##whereinR.sub.1 is H or CH.sub.3 ;R.sub.2 and R.sub.3 are selected from C.sub.1 alkyl and C.sub.2 alkyl;A.sub.1 is O;B.sub.1 is C.sub.2 alkyl or C.sub.3 alkyl; andX.sub.1.sup.- is an anionic counterion, and(b) at least one cationic polymer consisting of cationic monomers of formula: ##STR14##whereinR.sub.4 is H or CH.sub.3 ;R.sub.5 and R.sub.6 are selected from C.sub.1 alkyl and C.sub.2 alkyl;R.sub.7 is H, C.sub.1 alkyl or C.sub.2 alkyl;A.sub.2 is O;B.sub.2 is C.sub.2 alkyl or C.sub.3 alkyl; andX.sub.2.sup.- is an anionic counterion.