Patent ID: 7767092
Filing Date: 2010-08-03
Classification: C02F,Y10S

Abstract:
1. A method of decolorizing a colored aqueous effluent comprising (i) a colored substance; and (ii) a polyvalent carboxylic acid or a polyvalent aminocarboxylic acid chelating agent containing two or more carboxylic acid groups, the method comprising the steps of: (a) controlling a hydrogen ion exponent (pH) of the colored effluent to be in a range in which said two or more carboxylic acid groups in the polyvalent carboxylic acid or the polyvalent aminocarboxylic acid do not dissociate; (b) adding an inorganic metal salt to the colored effluent so as to allow the inorganic metal salt to react with the colored substance to form a precipitation including coagulants in the colored effluent, wherein said range and said coagulants result in a structure which tends not to re-dissolve the colored substance in the aqueous effluent, and (c) eliminating the precipitation from the colored effluent.