Patent GB-799621-A (GB)
Title: Method for clarifying water
IPC: C09K23/52
Filed: 1956-06-15
Abstract: Furbidity in water is reduced by mixing with it an acrylamide polymer and a slurry of a bentonite.  In examples: (1) a dispersion containing 5 per cent by weight of a bentonite is heated at 90 DEG to 95 DEG  C. for two hours with occasional agitation. The resulting slurry is added to river water in portions to provide 50 p.p.m. bentonite by weight of water, the water being agitated by a propeller operating at 900 r.p.m.  The water is transferred to another vessel providing gentle stirring, and 0.5 p.p.m. of an acrylamide polymer is added from a 0.04 per cent by weight solution, stirring continuing for 15 minutes.  The viscosity of the polymer solution is 9.8 centipoises; (2) a slurry containing 2 per cent of another bentonite is added to river water in the amount of 25 p.p.m., and acrylamide polymer is introduced at 0.2 p.p.m. from an aqueous 0.04 per cent solution having a viscosity of 9 centipoises; (3) bentonite at 25 p.p.m. (from 2 per cent slurry) and acrylamide polymer at 0.3 p.p.m. are injected into the input line, through which river water is pumped, of a cylindrical settling vessel equipped, at its lower portion, with baffles and a low-speed agitator.  The water rises in the vessel at 1 inch per minute.  After 21 hours a dense layer of flocculated solids has built up in the lower section of the vessel; (4) turbid water containing 120 p.p.m. hardness calculated as CaCO3 is treated with an aqueous 2 per cent bentonite slurry at a rate of 50 p.p.m.  The aqueous acrylamide solution of Example (2) is thereupon added at a rate of 0.5 p.p.m.; (5) 50 p.p.m., as a 2 per cent slurry, of a bentonite, are mixed with river water by a rapidly-operating propeller during a period of one minute.  0.25 p.p.m. acrylamide polymer is added with gentle stirring, continued for twenty minutes, by agitators having 2.5 inch paddles, rotating at 40 r.p.m.  Settling followed.  U.S.A. Specification 2,362,022 is referred to.  Reference has been directed by the Comptroller to Specification 761,021.ALSO:Turbidity in water is reduced by mixing with it an acrylamide polymer and a slurry of a bentonite.  In examples: (1) a dispersion containing 5 per cent by weight of a bentonite is heated at 90 DEG  to 95 DEG C. for two hours with occasional agitation. The resulting slurry is added to river water in portions to provide 50 p.p.m. bentonite by weight of water, the water being agitated by a propeller operating at 900 r.p.m.  The water is transferred to another vessel providing gentle stirring, and 0,5 p.p.m. of an acrylamide polymer is added from a 0,04 per cent by weight solution, stirring continuing for 15 minutes.  The viscosity of the polymer solution is 9,8 centipoises.  (2) A slurry containing 2 per cent of another bentonite is added to river water in the amount of 25 p.p.m. and acrylamide polymer is introduced at 0,2 p.p.m. from an aqueous 0,04 per cent solution having a viscosity of 9 centipoises.  (3) Bentonite at 25 p.p.m. (from 2 per cent slurry) and acrylamide polymer at 0,3 p  p.p.m. are injected into the input line, through which river water is pumped, of a cylindrical settling vessel equipped, at its lower portion, with baffles and a low-speed agitator.  The water rises in the vessel at 1 in. per minute.  After 21 hours a dense layer of flocculated solids has built up in the lower section of the vessel.  (4) Turbid water containing 120 p.p.m. hardness calculated as CaCo3 is treated with an aqueous 2 per cent bentonite slurry at a rate of 50 p.p.m.  The aqueous acrylamide solution of example (2) is thereupon added at a rate of 0,5 p.p.m. (5) 50 p.p.m., as a 2 per cent slurry, of a bentonite, are mixed with river water by a rapidly-operating propeller during a period of one minute.  0,25 p.p.m. acrylamide polymer is added with gentle stirring, continued for twenty minutes, by agitators having 2,5 inch paddles rotating at 40 r.p.m.  Settling followed.  U.S.A. Specification 2,362,022 is referred to.  Reference has been directed by the Comptroller to Specification 761,021.