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.