Method of separation and extraction of D-lactic acid from sodium D-lactate fermentation liquid

The invention discloses a method of separation and extraction of D-lactic acid from sodium D-lactate fermentation liquid, belongs to the technical field of bio-engineering and particularly relates to the method of separation and extraction of D-lactic acid from the fermentation liquid. The method includes the steps of (1) performing solid-liquid separation to the sodium D-lactate fermentation liquid, removing proteins and pigments to obtain a clarified fermentation liquid; (2) decoloring the clarified fermentation liquid obtained in the step (1); (3) performing ion exchange to the fermentation liquid obtained in the step (2); and (4) concentrating the fermentation liquid after the ion exchange to obtain the D-lactic acid. In the method, only is normal-temperature acidification required so that the method is short in acidification time. The method is effectively reduced in the content of protein and a part of the pigments in the fermentation liquid and is free of generation of calcium sulfate which is low in additional value and is difficult to treat. The method is optimized in operation and is less in separation steps.