METHOD FOR PRODUCING LACTIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a method for economically producing high-purity lactic acid from a lactate salt produced by fermentation of a carbohydrate by microorganisms.SOLUTION: There is provided a method for producing lactic acid which comprises: a) a step of preparing an aqueous medium containing magnesium lactate; b) a step of adding a monovalent base to the aqueous medium to form an aqueous medium containing a water soluble monovalent lactate salt and a solid magnesium base; c) a step of separating the magnesium base from the aqueous medium; d) a step of adjusting the concentration of the monovalent lactate salt in the aqueous medium to a value of 10 to 30 wt.%; e) a step of subjecting the aqueous medium containing the monovalent lactate salt to water-splitting electrodialysis to produce a first solution containing a monovalent base and a second solution containing lactic acid and a monovalent lactate salt, in which the electrodialysis is performed to a partial conversion rate of 40 to 98 mol%; f) a step of separating the second solution containing lactic acid and a monovalent lactate salt into lactic acid and a solution containing a monovalent lactate salt by vapor-liquid separation; and g) a step of recirculating the solution in the step f) containing the monovalent lactate salt to the step d).SELECTED DRAWING: None