The aim of the project is, to operate and optimize a continuous product recovery process (here from itaconic acid). Continuous product recovery is hereby accomplished out of a running fermentation process. In this fermentation process, fungi cells of Ustilago maydis convert glucose continuously to itaconic acid.

For product recovery a submerged membrane process is applied, which is known from wastewater treatment. This submerged process in particular is characterized by hollow-fiber membranes, which are spirally wound up. For the operation of this submerged process, a new process has been developed at AVT.CVT called pulsed diafiltration. This process is characterized by a periodic reversal of the flow direction over the membrane: (1) Permeate is recovered over the membrane (outside-in filtration) and (2) nutrient solution containing glucose is added to the reactor (inside-out filtration). The backflush fluid, which is permeate in conventional filtration processes, is in this case the nutrient solution. This solution is needed by the fungi cells in the fermenter for itaconic acid production. By the periodic reversal equal amounts of fluid are exchanged, so there is no net flux over the membrane and cake-layer formation is prevented.

The pulsed diafiltration process has been successfully operated coupled to the fermentation process for several times. Thereby the productivity of the process could be significantly enhanced. In addition the process features high stability as well as high permeabilities, as compared to conventional submerged membrane processes. Hereby the product recovery of such complex, viscous fermentation broth can be guaranteed.

Relevant publication

F. Carstensen, A. Apel, M. Wessling: In situ product recovery: Submerged membranes vs. external loop membranes; Journal of Membrane Science 2012 (peer reviewed journal paper, published)

F. Carstensen, C. Marx, J. André, M. Wessling: Pulsed diafiltration for continuous in situ product recovery; Journal of Membrane Science (peer reviewed journal, submitted)

Patent:

Patent application „Verfahren zur Produktisolierung und Substratzufuhr in einem Bioreaktor“, Oktober 2010

Conference presentation:

Frederike Carstensen, Tobias Klement, Jochen Büchs, Matthias Wessling, Thomas Melin: Process Intensification by Pulsed Diafiltration for In Situ Product Recovery; ICOM, Amsterdam , Netherlands, 25-29.07.2011 (conference presentation, published)

Frederike Carstensen, Tobias Klement, Jochen Büchs, Matthias Wessling, Thomas Melin: Process Intensification by Pulsed Diafiltration for In Situ Product Recovery. North American Membrane Society, Las Vegas, United States of America, 06-08.06.2011 (conference presentation, published)