The invention discloses a method for purifying
long chain dicarboxylic acid in
fermentation broth. The method comprises the following steps: (I) adding
inorganic salts and an alkali solution into
fermentation broth, and stirring to dissolve the
inorganic salts, wherein under the synergistic effect of alkali and salts, the
cell wall of
bacteria are dissolved, broken, and demulsified; (II) allowing the
system to stand still to carry out layering, removing
solid impurities such as bacterium dregs, and recovering
alkane; (III) adding a proper amount of polyglycol into the
fermentation broth, and dissolving the
polymer to prepare a dual water phase
system; (IV) subjecting the obtained dual water phase
system to a super gravity treatment, wherein after the super gravity treatment, the upper phase and the lower phase are rapidly separated, proteins and pigments are dissolved in the upper phase, and the product (dicarboxylate salts) is dissolved in the lower phase; and (V) acidifying the lower phase obtained in the step (IV) to precipitate
dicarboxylic acid crystals, and performing cooling, filtering,
water washing, and
drying to obtain a refined
dicarboxylic acid product. A dual water phase extraction technology and a super gravity technology are combined to refine
long chain dicarboxylic acid, the technical flow is shortened, the investment of equipment, time, and energy is saved, and the refined product has the advantages of high purity and low content of
total nitrogen.