In situ recovery of fumaric acid by intermittent adsorption with IRA-900 ion exchange resin for enhanced fumaric acid production by Rhizopus oryzae

• An adsorption process with IRA900 resins was developed for in situ recovery of fumaric acid.
• The adsorption on a fixed bed column can be modeled with the Yoon–Nelson equation.
• Efficient fumaric acid desorption and resin regeneration were achieved with 0.7 M NaCl.
• Fermentation with in situ recovery enhanced fumaric acid yield by 25% and productivity by 59%.

An in situ separation method for fumaric acid recovery by adsorption from fermentation broth was developed with IRA900, which was selected for its high adsorption capacity at the fermentation-favored pH of 5 and high selectivity against impurities (glucose and malic acid). The adsorption of fumaric acid in a fixed bed column was evaluated, and the effects of resin ion form (Cl− or OH−), feed flow rate (2.34–5.34 mL min−1), and stripping agent (NaOH or NaCl) on the process were investigated. The results showed that the best conditions were the ion form of Cl−, feed flow rate of 4.10–5.34 mL min−1 and 0.7 M NaCl as the stripping agent. An intermittent in situ adsorption process was then demonstrated by coupling the fixed bed column with a stirred-tank bioreactor through medium recirculation during the fermentation. After saturating the resin in ∼3 h, desorption was performed with 0.7 M NaCl for ∼1 h, which stripped out all the fumaric acid adsorbed on the resin and simultaneously regenerated the resin to its original chloride form for immediate reuse in another adsorption cycle. Compared to the batch fermentation without adsorption, intermittent in situ recovery of fumaric acid increased the yield by 25% and productivity by 59%.