Patent ID: 8349597
Filing Date: 2013-01-08
Classification: B01D,C12P

Abstract:
1. A method of producing lactic acid comprising the steps of: (a) producing lactic acid in a first culture solution by microbial fermentation, wherein a calcium salt is added to the first culture solution to maintain a selected pH during the microbial fermentation and then removing the resulting calcium component in said first culture solution as a poorly-soluble sulfate salt to obtain a second culture solution; (b) filtering the second culture solution through a nano-filtration membrane to obtain a first filtered culture solution; (c) filtering the first filtered culture solution through a reverse osmosis membrane to obtain a second filtered culture solution, thereby increasing the concentration of lactic acid in the second filtered culture solution; and (d) distilling the second filtered culture solution under a pressure of 1 Pa to atmospheric pressure at a temperature of 25° C. to 200° C. to recover substantially optically pure lactic acid.