Amino Acid, Carbohydrate and Acrylamide Polymers useful as Flocculants in Agricultural and Industrial Settings

Abstract

Modified polysaccharides, acrylamide copolymers, water-soluble amino acid copolymers, and combinations thereof are described for uses including flocculation of solids, particularly flocculation of soil in an agricultural settings and clarification of process waters from oil-sands mining operations. Also described are methods of preparing selected amino acid copolymers and modified polysaccharides.

We claim: 
     
         1 . A method of clarifying hydrocarbon- and bitumen-containing process water obtained from an oil-sands mining operation, said method comprising:
 adding a coagulant to said process water, wherein said coagulant is an aluminum, iron, or calcium salt or a polycationic polymer; and   adding an anionic flocculant to said process water, wherein the flocculant is an anionic polymer.   
     
     
         2 . The method of  claim 1  wherein the polymeric coagulant is selected from polyaluminate, a polymer of epichlorohydrin and dimethyl amine (polyEPI/DMA) and/or a polymer of diallyl dimethyl ammonium chloride (polyDADMAC). 
     
     
         3 . The method of  claim 1 , wherein said polycationic coagulant is polyEPI/DMA. 
     
     
         4 . The method of  claim 1  wherein the polymeric coagulant has a molecular weight less than 1 million Daltons. 
     
     
         5 . The method of  claim 1  wherein the anionic flocculant is an acrylamide/acrylate polymer. 
     
     
         6 . The method of  claim 1  wherein the anionic flocculant has a molecular weight of at least 1 million Daltons and a mole % acrylamide of at least 50%. 
     
     
         7 . The method of  claim 1 , wherein said coagulant is added to said process water, together with, or prior to, said anionic acrylamide copolymer 
     
     
         8 . The method of  claim 1 , wherein said process water is acidified prior to adding said coagulant and/or said anionic acrylamide copolymer. 
     
     
         9 . The method of  claim 8  wherein said process water is acidified to a pH of about 2-4. 
     
     
         10 . The method of  claim 1 , wherein said method comprises adding a flocculant composition, wherein said composition comprises an activated, pregelatinized or maleamate-modified starch and said anionic acrylamide copolymer. 
     
     
         11 . The method of  claim 10 , wherein said composition comprises the activated starch. 
     
     
         12 . The method of  claim 11 , wherein said composition contains said activated starch and acrylamide copolymer in a ratio between about 0.1:1 and 100:1. 
     
     
         13 . The method of  claim 1 , wherein the total amount of additives is in the range of about 2 ppm to about 500 ppm relative to said process water. 
     
     
         14 . The method of  claim 13 , wherein the total amount of additive is in the range of about 2 ppm to about 100 ppm relative to said process water. 
     
     
         15 . The method of  claim 1 , wherein said anionic acrylamide copolymer has a molecular weight of at least 4 million Daltons. 
     
     
         16 . The method of  claim 1 , wherein said polycationic coagulant has a molecular weight less than 500 kiloDaltons. 
     
     
         17 . The method of  claim 1 , comprising the steps of:
 (a) adjusting the pH of said process water to about 2-4;   (b) adding a coagulant to said process water, wherein said coagulant is an inorganic aluminum, iron, or calcium salt, or a polycationic copolymer that has a molecular weight less than 1 million Daltons and a mole % cationic monomer of at least 50%; and   (c) adding a flocculant comprising an anionic acrylamide copolymer and an activated starch to said process water, wherein said acrylamide copolymer has a molecular weight of at least 1 million Daltons and a mole % acrylamide of at least 50%.   
     
     
         18 . The method of  claim 17 , wherein the polymeric coagulant is selected from a polymer of polyaluminate, a polymer of epichlorohydrin and dimethyl amine (polyEPI/DMA) and/or a polymer of diallyl dimethyl ammonium chloride (polyDADMAC). 
     
     
         19 . The method of  claim 18 , wherein said polycationic coagulant is polyEPI/DMA. 
     
     
         20 . The method of  claim 19 , wherein said oil-sand mining operation is steam assisted gravity drainage (SAGD) operation.