PRODUCING METHOD OF PURIFIED LACTIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a producing method of purified lactic acid, which is a process of concentrating a lactic acid fermentation liquid at a low temperature.

SOLUTION: The producing method of purified lactic acid comprises: a fermentation process where a pH adjusting agent containing calcium and a microorganism are added to a sugar-containing solution to produce lactic acid in the form of calcium lactate; and a purification process where sulfuric acid is added to a solution containing calcium lactate to separate calcium ions in the form of calcium sulfate. The producing method of purified lactic acid further comprises, prior to the process of adding sulfuric acid: a reverse osmosis membrane concentration process 140 where the solution containing calcium lactate is allowed to pass through a reverse osmosis membrane to remove water; a crystallization process 150 where the obtained concentrated liquid of calcium lactate is cooled to crystallize and remove the calcium lactate; and a reverse osmosis membrane concentration process 140 where the solution, from which calcium lactate has been removed, is heated and allowed to pass through the reverse osmosis membrane to remove water; wherein the crystallization process 150 and the subsequent reverse osmosis membrane concentration process 140 are repeated one or more times.

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