Patent ID: 6258277
Filing Date: 2001-07-10
Classification: C02F,Y10S

Abstract:
A method for simultaneously precipitating soluble heavy metal ions from semiconductor wastewater containing abrasive solids and enhancing the operation of a microfilter comprising the steps of:(a) adding an effective amount of a water-soluble polymer containing dithiocarbamate functionalities to semiconductor wastewater containing abrasive solids;wherein said soluble heavy metal ions are selected from the group consisting of copper, nickel, zinc, lead, mercury, cadmium, silver, iron, manganese and mixtures thereof;wherein said abrasive solids are selected from the group consisting of alumina, silica, ceria, germania, titania, zirconia and mixtures thereof;wherein said microfilter has a molecular cutoff size in the range of about 0.1 to about 5 microns;wherein said water-soluble polymer containing dithiocarbamate functionalities is selected from the group consisting of polydiallylaminedithiocarbamate, and water-soluble polymers containing dithiocarbamate functionalities with an ethylenedichloride-ammonia condensation backbone; wherein said water-soluble polymer containing dithiocarbamate functionalities is added to said wastewater in an amount of at least about 200 ppm;wherein said water-soluble polymer containing dithiocarbamate functionalities has from about 35% to about 50% CS.sub.2 incorporation;wherein said enhancing the operation of a microfilter operation means increasing the amount of Average Flux by an increase of at least 48 gal/ft.sup.2 /day;(b) precipitating said heavy metal ions: and(c) passing said wastewater through a microfilter to remove the abrasive solids and precipitated heavy metal ions.