One step recovery of succinic acid from fermentation broths by crystallization

Succinic acid is a valuable four-carbon platform chemical with wide applications in many fields. One step recovery of the desired product succinic acid crystal from the fermentation broths was studied for the first time. In a fed batch fermentation by Actinobacillus succinogenes BE-1, the final concentrations of succinic acid, formic acid, lactic acid and acetic acid in the bioreactor reached 97.8 g/L, 23.5 g/L, 5.1 g/L and 17.4 g/L, respectively. These organic acids have different proportions of dissociated and undissociated forms at different pH values, and the solubility of these forms of acid is different substantially. When the pH value of the fermentation broth was controlled less than 2.0, crystallization of succinic acid could be carried out at 4 °C easily, while major acid by-products such as lactic acid, acetic acid and formic acids were miscible in solution. By this one step recovery method, succinic acid yield was 70%, and the purity was 90%. In comparison, for traditional calcium precipitation coupled ion-exchange adsorption, the yield and purity were 52% and 92%, respectively. Crystallization could be regarded as not only the final purification step but also the first recovery step for the downstream separation process. In this study, succinic acid can be feasibly purified from fermentation broths selectively, which could be integrated with other separation method to optimize the downstream process.