Fumaric acid separation from fermentation broth using nanofiltration (NF) and bipolar electrodialysis (EDBM)

• NF and EDBM were applied to separate and concentrate fumaric acid from fermentation broth.
• The influence of electrodialysis stack configuration on the efficiency of EDBM process was analysed.
• The retention of fumaric acid in NF process increased strongly with increasing pH of initial solution.

The suitability of two techniques: nanofiltration (NF) with ceramic membrane and bipolar electrodialysis (EDBM), in separation and concentration of fumaric acid from fermentation broth obtained during biotechnological conversion of glycerol, was investigated. The influence of composition, concentration and pH of fumaric acid model solutions on the efficiency of nanofiltration process was studied. It was found that the retention of fumaric salts increased strongly with increasing pH of the initial solution, while the retention of glycerol was lower than 6%, irrespective of pH. In the second step, the influence of electrodialysis stack configuration, current density, pH and concentration of fumaric acid in model solutions on the efficiency of bipolar electrodialysis was analysed. Then, after NF pretreatment, EDBM process of simulated solutions as well as fermentation broth was performed. The current density equal to 50 A/m2 was found sufficient to achieve a 53% desalination of fumaric acid from fermentation broth. Moreover, the results obtained showed that bipolar electrodialysis stack, consisting of anion-exchange and bipolar membranes, allowed selective separation of fumaric acid from the broth.The results suggest that NF with ceramic membrane as well as EDBM can be effectively applied as a removal step of fumaric acid from fermentation broth.

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