Patent ID: 8597515
Filing Date: 2013-12-03
Classification: C02F

Abstract:
1. A method of purifying oil sand process water, comprising: (a) sending utilized process water from a bitumen extraction process to a tailings setting pond; (b) treating water from the tailings settling pond 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; (c) passing the treated water through a membrane separation system at a sustainable flux, wherein the sustainable flux is 60-70% of a critical flux determined for the water from the tailings settling pond treated with one or more of said polymers; (d) optionally, passing the permeate from step (c) through an additional membrane filtration system that is a submerged membrane system, an external membrane separation system, or a combination thereof; and (e) sending the permeate back for use in a bitumen extraction process; wherein said effective amount of cationic polymers is from about 0.05 ppm to about 400 ppm active solids; wherein said effective amount of amphoteric polymers is from about 1 ppm to about 500 ppm of active solids; wherein the effective amount of zwitterionic polymers is from about 1 ppm to about 500 ppm active solids; wherein the critical flux is determined for the water from the tailings settling pond treated with one or more of said polymers by monitoring trans-membrane pressure for 15 minutes at a first lowest flux of 30 liters per square meter per hour (LMH), and then after 15 minutes monitoring trans-membrane pressure at a next higher flux, continuing the procedure of increasing flux and measuring trans-membrane pressure until a trans-membrane pressure of 2.5-3 pounds per square inch is reached.