Patent ID: 6217778
Filing Date: 2001-04-17
Classification: C02F,Y10S

Abstract:
A method of clarifying industrial waste water comprising adding to the waste water from about 0.1 to about 50 ppm of a high molecular weight water-soluble anionic or nonionic dispersion polymer wherein the dispersion polymer has a bulk Brookfield viscosity of from about 10 to about 25,000 cps at 25.degree. C. and comprises from about 5 to about 50 weight percent of a water soluble polymer prepared by polymerizing under free radical forming conditions at a pH of from about 3 to about 8 in an aqueous solution of a water-soluble salt in the presence of a stabilizer:i. 0 to about 30 mole percent of acrylic acid or methacrylic acid or the alkali metal, alkaline earth metal or ammonium salts thereof, and,ii. 100 to about 70 mole percent of acrylamide;wherein the stabilizer is an anionic water-soluble copolymer of acrylic acid or methacrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid having an intrinsic viscosity in 1M NaNO.sub.3 of from about 0.1-10 dl/g and comprises from about 0.1 to about 5 weight percent based on the total weight of the dispersion, wherein the copolymer comprises from about 3 to about 60 weight percent 2-acrylamido-2-methyl-1-propanesulfonic acid and from about 97 to about 40 weight percent acrylic acid; or from about 11 to about 95.5 weight percent 2-acrylamido-2-methyl-1-propanesulfonic acid and from about 89 to about 4.5 weight percent methacrylic acid, and the water soluble salt is selected from the group consisting of ammonium, alkali metal and alkaline earth metal halides, sulfates, and phosphates and comprises from about 5 to about 40 weight percent based on the weight of the dispersion, and clarifying said industrial waste water.