Patent ID: 7722841
Filing Date: 2010-05-25
Classification: C02F

Abstract:
1. A method for treating CMP waste which comprises treating the waste with a coagulant to separate solids from metals, and without ion exchange removing the chelated metals from filtrate by co-precipitation with a combination of about 300-800 ppm of the coagulant and about 300-800 ppm of a polymeric chelant, wherein (a) the polymeric chelant has the formula: wherein R 1 independently is —CH 2 CO 2 R 2 , —CH 2 —PO 3 R 2 , or mixtures thereof; R 2 each independently represents —H or a cation; and the sum of x, y and z is an integer greater than 15; and (b) the coagulant is composed of a water soluble or dispersible copolymer of a tannin and 2-acryloxyethyltrimethyl ammonium chloride (AETAC).