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CACD – that stands for Citric Acid Cool Device. But it wasn’t just the device that was ‘cool’; the whole competition and the Mittweida team were too. In mid-July, the Institute of Food and Bioprocess Engineering at TU Dresden hosted the 99€ Bioreactor Competition for the 10th time, welcoming 11 teams to the Saxon capital.
Conventional trickle stones and other equipment from the aquarium trade were used to build the reactor. The planned pH control system, comprising a pH electrode and a pump, failed shortly before the competition began for technical reasons, whereupon the team responded with great ingenuity: A syringe containing diluted caustic soda was quickly glued to a shelf, and the flow rate was adjusted using a hose clamp so that the drip rate would be sufficient to stabilise the pH level between 4.5 and 5.5. The reactor itself was housed in a repurposed beer keg to prevent any potential water damage. This unusual ‘packaging’ ultimately generated a great deal of excitement, as the interior of the reactor remained a mystery to the competing teams throughout the entire 24-hour cultivation period.
With a yield of 0.616 g and a low cost of €66.86, HS Mittweida ultimately secured 5th place. The winners were the home team from TU Dresden, with an impressive yield of 2.88 g of citrate.
We offer our warmest congratulations on this success!
References
[1] Anna Żywicka et al, ‘Significant enhancement of citric acid production by Yarrowia lipolytica immobilised in a bacterial cellulose-based carrier’, *Journal of Biotechnology*, Volume 321, 2020, pp. 13–22, ISSN 0168-1656, doi.org/10.1016/j.jbiotec.2020.06.014.
[2] Książek, E., 2023. Citric Acid: Properties, Microbial Production, and Applications in Industries. Molecules 29, 22. doi.org/10.3390/molecules29010022
[3] Reschetilowski, W. (Ed.), 2020. Handbook of Chemical Reactors: Chemical Reaction Engineering: Theoretical and Practical Fundamentals, Chemical Reaction Apparatus in Theory and Practice, Springer Reference Natural Sciences. Springer Berlin Heidelberg, Berlin, Heidelberg. doi.org/10.1007/978-3-662-56434-9
[4] Behr, A., Agar, D.W., Vorholt, A.J., Jörissen, J., 2025. Introduction to Technical Chemistry. Springer Berlin Heidelberg, Berlin, Heidelberg. doi.org/10.1007/978-3-662-70148-5
