Aluminum Company of America

John W Novak

Gary A O'Neill

Edward S Martin

A dry flocculant powder comprises an inorganic substrate consisting essentially of metal oxide/hydroxide particles having an average particle size of less than about 30 microns, said substrate having a cationic or anionic polyelectrolyte coated onto its outer surface, preferably under other than high shear conditions. A method for coating or adhering polyelectrolytes to the outermost surface of inorganic particles comprises dispersing a polyelectrolyte in a substantially non-aqueous solvent, preferably having a low boiling point and a low to intermediate polarity relative to the polyelectrolyte; adding the inorganic particles to the solvent to form a slurry; mixing the slurry under low to moderate shear conditions; and removing excess solvent from the slurry. There is also disclosed a method for removing clay, clay-like materials, humic acids, yeast, biological cells and/or other cell debris from an aqueous stream through contact with the aforementioned dry flocculant powder.

Method for using a flocculant powder

A method is disclosed for reducing the amount of a first contaminant and second contaminant in a solution to environmentally safe levels, said solution having a substantially greater amount of the first contaminant than the second contaminant. The method comprises: contacting the solution with an activated or calcined product of a compound having the formula A.sub.6 B.sub.2 (OH).sub.16 C.4H.sub.2 O, wherein A is a divalent metal cation, B is a trivalent metal cation and C is a mono- to tetravalent anion. The method further comprises separating the solution from the contacted product. The method is particularly useful for removing both selenium and sulfate, arsenic and sulfate, or arsenic and phosphate from a waste water stream. An unpredicted preference for selenium and arsenic, in the presence of other contaminants including sulfate and phosphate, was also shown herein.

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Murrysville, PA, United States of America

John W Novak