Integrated product removal of slightly water-soluble carboxylates from fermentation by electrochemically induced crystallization

Fermentation technology is potentially sustainable for its use of renewable feedstocks. Large-scale application requires efficient downstream processing integrated with fermentation, which can be established by in situ product removal. In this field, the removal of slightly water-soluble compounds that are subject to speciation is challenging. Application of electrodialysis (ED), promising for product removal of charged compounds, is limited for slightly water-soluble components. Our approach, electrochemically induced crystallization (EIC), makes use of crystallization of slightly water-soluble components inside ED modules as a means of in situ product removal.Proof-of-principle experiments show that EIC effectively decreases concentrations of several carboxylic acids in aqueous systems. Fermentation experiments with Pseudomonas putida S12 indicated that integration of EIC with bio-based processes should be in an external loop with indirect contact to avoid a decrease in biomass activity and fouling of biomass inside the ED module. The implementation study demonstrates that high product removal rates can be maintained by regenerating the ED module using an auxiliary phase. © 2010 Elsevier B.V.