New process for extracting lactic acid from lactic acid fermentation liquid

Abstract

The invention discloses a new process for extracting lactic acid from lactic acid fermentation liquid. The process flow comprises the following steps: preparing the fermentation liquid, deproteinizing, removing bacteria, decolorizing with activated carbon, performing plate and frame filtration, filtering with an inorganic ceramic membrane, cooling by a plate type heat exchanger, filtering with an organic nano-filtration membrane, concentrating and performing primary crystallization, performing centrifugal drying, performing resolvation, performing acidolysis, passing through an ion exchange resin column and concentrating to obtain a finished product. The process flow performs membrane filtration twice, namely the filtration with the inorganic ceramic membrane and the filtration with the organic ceramic membrane, wherein the filtration with the inorganic ceramic membrane can remove small insoluble solid impurities, bacteria, colloidal substances, macromolecular sugars and other impurities in filtrate; the filtration with the organic nano-filtration membrane can remove low-molecular weight sugars and multivalent ions in the filtrate; and the purity of the finally prepared finished product lactic acid is as high as 95%-98%, the crystallization yield of the lactic acid is improved from original 70% to above 85%, and the production cost is greatly reduced.

Description

technical field [0001] The invention relates to a process for separating and purifying lactic acid, in particular to a process for separating and purifying lactic acid from lactic acid fermentation broth by using a membrane. Background technique [0002] Lactic acid, as an important organic acid, widely exists in human body, animal body and plant. Lactic acid, lactate and its derivatives are widely used in food, feed, chemical and pharmaceutical fields. In recent years, poly-L-lactic acid produced by the polymerization of L-lactic acid has been used as a new material to manufacture biodegradable plastics, green packaging materials and household films. The most promising new material in the new century has a very broad application prospect. [0003] The production methods of lactic acid include fermentation method, chemical synthesis method and enzymatic method. At present, the production of L-lactic acid with high optical purity is mainly based on microbial fermentation, ...

AI Technical Summary

Problems solved by technology

[0006] The process has the advantages of easy control and simple equipment requirements, but the product extraction rate is low and the purity is not high

The reasons for the low extraction rate and low purity of lactic acid are as follows: major impurities such as sugars, proteins and pigments in the fermentation broth cannot be effectively removed, which significantly affects the crystallization rate and purity of calcium lactate; The loss rate of lactic acid is as high as 30%; the sugar removal in the process is insufficient, resulting in residual sugar or other reducing substances in the finished lactic acid affecting the quality of the product