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US 5,326,479 AGranted
Treatment of pulp and paper wastewater with reducing agent and a polymer for color removal
AssigneeNalco Chemical Company
InventorsJawed M. Sarkar, Amy M. Tseng, John H. Collins
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Abstract
A process for removing color from a pulp and paper wastewater which comprises the following steps: (a) treating the wastewater with a reducing agent which is capable of inactivating color producing functional groups of the wastewater; and (b) treating the wastewater subsequent to step (a) with a polymer which is capable of removing color from the wastewater.
Claims7
A process for removing color from a pulp and paper wastewater containing aldehyde and keto-enol color producing functional groups which comprise the following steps:
- (a) treating said wastewater with an effective amount of reducing agent selected from the group consisting of sodium bisulfite, sodium hydrosulfite and sodium persulfate to convert at least some of the color producing functional groups of said wastewater to anionically charged addition products, wherein the pH of the wasterwater is in the range between about 6.0 to about 11.0;
- (b) treating said wastewater subsequent to step (a) with a cationic polymer which is capable of removing color including said addition products from said wastewater, wherein said cationic polymer is at least one polymer and/or copolymer selected from the group consisting of an epichlorohydrin-dimethylamine polymer, polyethyleneimines, polydiallyldimethylammonium chloride, copolymers of polydiallyldimethylammonium chloride and acrylamide, and an ethylenedichloride-ammonia polymer;
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- (c) removing said color including said addition products from said wastewater.
1 more element
Dependencies are inferred from the claim text.