Patent ID: 8252350
Filing Date: 2012-08-28
Classification: C12F

Abstract:
1. A method of separating and removing an aqueous ethanol mixture from an active ethanol fermentation broth, the method comprising the steps: (a) supplying a selected fraction of the active ethanol fermentation broth to a first reverse osmosis membrane separation stage to generate a dilute aqueous ethanol mixture permeate and a reduced ethanol content fermentation broth retentate; (b) recycling the reduced ethanol content fermentation broth retentate to the active ethanol fermentation broth to suppress ethanol inhibition thereof; (c) supplying the dilute aqueous ethanol mixture permeate to a second membrane separation stage comprising a reverse osmosis membrane separation system, the first and second membrane separation stages operate at a pressure between about 500 to about 900 PSI and at a temperature between about 110 and about 130 degrees F., to generate a concentrated aqueous ethanol mixture retentate and a dilute aqueous ethanol mixture permeate; and (d) recycling the dilute aqueous ethanol mixture permeate of step (c) to the active ethanol fermentation broth to suppress ethanol inhibition thereof.