Fermentation Technology

 

The AVT.BioVT has a wide range of expertise in the field of fermentation technology. In addition to numerous 1-2 L laboratory fermenters, the portfolio also includes four steel fermenters with total volumes between 7.5 L and 150 L, with which scale-up up to pilot plant scale is possible. These fermenters enable unique fermentation experiments.

7.5 L fermenters for the fermentation of synthesis gas

The AVT.BioVT operates two bioreactors, each with a total volume of 7.5 L and equipped with a 50 L storage tank. The two fermenters can be connected to operate as a continuous fermenter cascade. In a cascade operation, the outlet of one reactor is connected to the inlet of a second reactor. In this way, excess substrate, or products from the first fermenter, can be further used in the second fermenter. Thus, higher yields can be achieved. It is also possible to use the first reactor for the formation of cell mass (biocatalyst) and the second for product formation. This is particularly advantageous in microbial systems where product formation is subject to catabolite repression. One of the two fermenters is ATEX-certified and therefore allows, among other things, anaerobic fermentation with synthesis gas (CO, CO2, H2) or aerobic fermentation of CH4. With this device, as in all steel fermenters of the AVT.BioVT, overpressure operation of up to 10 bar is possible. Due to the increasing oxygen transfer into the culture broth with increasing reactor pressure, fermentations with extremely high oxygen demand, such as high cell density fermentations, can be carried out. The mode of operation (batch, extended batch, fed-batch and continuous mode) can be flexibly selected as required. An off-gas analysis system for O2, CO, CO2, CH4 and H2, as well as various measurement and control equipment, are also integrated into the fermenter.

50 L pressure fermenter

The AVT.BioVT also has a pressure fermenter with a total volume of 50 L, which can be operated with an overpressure of up to 10 bar, too. The fermenter has a three-staged agitation system, which is geometrically designed according to the standardization recommendation of the DECHEMA. The fermenter is equipped with a comprehensive measurement and control system. Thus, measurement and control of temperature, pH, stirrer speed, dissolved oxygen, reactor pressure and power input (torque, measured between mechanical seal and stirrer) are possible. In addition, the system features off-gas analytics for measuring oxygen and carbon dioxide partial pressures in the gas phase. An integrated reactor calorimetry, which calibrates itself regularly during operation via heating cartridges, enables monitoring of the fermentation by recording the heat generated by the microorganisms1.

150 L pressure fermenter

As part of the Competence Center NGP² Biorefinery, the AVT.BioVT operates a pilot-scale pressurised fermenter. The fermenter is designed for operation at up to 10 bar overpressure and has a total volume of 150 L. In addition to waste gas analysis, the fermenter also has the option of calorimetry measurements. In addition, cells can be continuously retained and permeate discharged via an external membrane circuit. Since the reactor is ATEX-certified, in-situ extraction with solvents can also be implemented in the reactor. Within the Competence Center NGP² Biorefinery there are various possibilities to realize integrated bioprocesses in pilot plant scale together with the staff of the other AVT chairs. Biomass digestion (enzymatic, chemical, thermal) as well as various downstream processing units such as filtration, centrifugation, crystallization, extraction and rectification are available in the pilot-scale plant.

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We continuously offer theses on the mentioned topics. You can find student and final theses here access only from the RWTH network). In addition, you are welcome to send us a spontaneous application via our .

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References

1 Regestein, L., Maskow, T., Tack, A., Knabben, I., Wunderlich, M., Lerchner, J. and Büchs, J. (2013), Non‐invasive online detection of microbial lysine formation in stirred tank bioreactors by using calorespirometry. Biotechnol. Bioeng., 110: 1386-1395. https://doi.org/10.1002/bit.24815