Purification of oil sands pond water

Abstract

A method of enhancing flux of tailings settling pond water from an oil sands process through a membrane separation system and purifying the water comprising is disclosed. The process comprises the following steps: (a) treating the water with an effective amount of one or more water-soluble cationic polymers, amphoteric polymers, zwitterionic polymers, or a combination thereof; (b) passing the treated water through a membrane separation system; and (c) optionally, passing the permeate from step (b) through an additional membrane separation system.

1 . A method of enhancing flux of tailings settling pond water from an oil sands process through a membrane separation system and purifying the water comprising the following steps:
 (a) treating the tailings settling pond water with an effective amount of one or more water-soluble cationic polymers, amphoteric polymers, zwitterionic polymers, or a combination thereof, wherein the tailings settling pond water contains total suspended solids (TSS) from about 2 to about 1.000 ppm prior to said treatment;   (b) passing the treated water through the membrane separation system; and   (c) optionally, passing the permeate from step (b) through an additional membrane separation system.   
     
     
         2 . The method of  claim 1 , wherein said membrane separation system has at least one membrane selected from the group consisting of: an ultrafiltration membrane; a microfiltration membrane; and a combination thereof. 
     
     
         3 . The method of  claim 1 , wherein said additional membrane separation system has at least one membrane selected from the group consisting of: an ultafiltration membrane having a pore size smaller than for a different ultrafiltration membrane used in said membrane separation system; a nanofiltration membrane; a reverse osmosis membrane; and a combination thereof. 
     
     
         4 . The method of  claim 1 , wherein the membrane separation system is a submerged membrane system, an external membrane separation system, or a combination thereof. 
     
     
         5 . The method of  claim 1  wherein the additional membrane separation system is a submerged membrane system, an external membrane separation system, or a combination thereof. 
     
     
         6 . The method of  claim 1 , wherein the amphoteric polymers are selected from the group consisting of at least one of the following: dimethylaminoethyl acrylate methyl chloride quaternary salt/acrylic acid copolymer, diallyldimethylammonium chloride/acrylic acid copolymer, dimethylaminoethyl acrylate methyl chloride salt/N,N-dimethyl- N-methacrylamidopropyl-N-(3-sulfopropyl)-ammnonium betaine copolymer, acrylic acid/N,N- dimethyl-N-methacrylarnidopropyl-N-(3-sulfopropyl)-ammmonium betaine copolymer and DMAEA.MCQ/Acrylic acid/N,N-dimenthyl-N-methaciylamidopropyl-N-(3-sulfopropyl)- arnmonium betaine terpolymer. 
     
     
         7 . The method of  claim 1 , wherein said effective amount of amphoteric polymers is from about 1ppm to about 500 ppm of active solids. 
     
     
         8 . The method of  claim 1 , wherein the amphoteric polymers have a weight average molecular weight of about 5,000 to about 2,000,000 daltons. 
     
     
         9 . The method of  claim 1 , wherein the amphoteric polymers have a cationic charge equivalent to an anionic charge equivalent ratio of about 4.0:6.0 to about 9.8:0.2. 
     
     
         10 . The method of  claim 1 , wherein the cationic polymers are selected from the group consisting of at least one of the following: polydiallyldimethylammonium chloride; polyethyleneimine; polyepiamine; polyepiamine crosslinked with ammonia or ethylenediamine; condensation polymer of ethylenedichloride and ammonia; condensation polymer of triethanolamine and tall oil fatty acid; poly(dimethylaminoethylmethacrylate sulfuric acid salt); and poly(dimethylaminoethylacrylate methyl chloride quaternary salt). 
     
     
         11 . The method of  claim 1 , wherein the cationic polymers are copolymers of acrylamide and one or more cationic monomers selected from the group consisting of: diallyldimethylammonium chloride, dimethylaminoethylacrylate methyl chloride quaternary salt, dimethylarninoethylmethacryl ate methyl chloride quaternary salt and dimethylaminoethylacrylate benzyl chloride quaternary salt. 
     
     
         12 . The method of  claim 1 , wherein said effective amount of cationic polymers is from about 0.05 ppm to about 400 ppm active solids. 
     
     
         13 . The method of  claim 1 , wherein the cationic polymers have a cationic charge of at least about 5 mole percent. 
     
     
         14 . The method of  claim 1 , wherein the cationic polymers have a cationic charge of 100 mole percent. 
     
     
         15 . The method of  claim 1 , wherein the cationic polymers have a weight average molecular weight of about 100,000 to about 10,000,000 daltons. 
     
     
         16 . The method of  claim 1 , wherein the zwitterionic polymers are composed of about 1 to about 99 mole percent of N,N-dimethyl-N-methacrylainidopropyl-N-(3- sulfopropyl)-ammonium betaine and about 99 to about 1 mole percent of one or more nonionic monomers. 
     
     
         17 . The method of  claim 1 , wherein the effective amount of zwitterionic polymers is from about 1 ppm to about 500 ppm active solids. 
     
     
         18 . The method of  claim 1 , wherein the tailings settling pond water contains TS from about 10 to 10,000 ppm; oil and grease from about 1 to about 100 ppm; TOC from about 1 to about 100 ppm; pH from about 7 to about 9; turbidity from about 2 to about 500 NTU; and color from about 5 to about 100 Pt-Co units.