Method and system for extracting long chain dicarboxylic acid

A system for extracting long chain dicarboxylic acid, comprising

• a primary membrane filtration unit, for a first membrane filtration of a long chain dicarboxylic acid fermentation broth to give a first filtrate;
• a first crystallization unit, for an crystallization by acidification or cooling for crystallization of a first filtrate obtained by the first membrane filtration to give a first solid-liquid mixture;
• a first separation unit, for a solid-liquid separation of the first solid-liquid mixture to give a first solid;
• a dissolution tank, for making the solid separated in the first separation unit into a solution;
• a crystallization by acidification unit, for crystallization by acidification of the solution formed by the dissolution tank to give a second solid-liquid mixture;
• a second separation unit, for a solid-liquid separation of the second solid-liquid mixture to give a second solid;
• a second crystallization unit, for mixing the solid separated in the second separation unit with water to form a mixture and subjecting the mixture to thermostatic treatment and cooling for crystallization to give a third solid-liquid mixture;
• and
• a third separation unit, for a solid-liquid separation of the third solid-liquid mixture.