Monitoring gradient formation in a jet aerated bioreactor

Abstract

Jet aerated loop reactors (JLRs) provide high mass transfer coefficients (kLa) and can be used for the intensification of mass transfer limited reactions. The jet loop reactor achieves higher kLa values than a stirred tank reactor (STR). The improvement relies on significantly higher local power inputs (∼104) than those obtainable with the STR. Operation at high local turnover rates requires efficient macromixing, otherwise reactor inhomogeneities might occur. If sufficient homogenization is not achieved, the selectivity of the reaction and the respective yields are decreased. Therefore, the balance between mixing and mass transfer in jet loop reactors is a critical design aspect. Monitoring the dissolved oxygen levels during the turnover of a steady sodium sulfite feed implied the abundance of gradients in the JLR. Prolonged mixing times at identical power input and aeration rates (∼100%) were identified for the JLR in comparison to the STR. The insertion of a draft tube to the JLR led to a more homogenous dissolved oxygen distribution, but unfortunately a reduction of mixing time was not achieved. In case of increased medium viscosities as they may arise in high cell density cultivations, no gradient formation was detected. However, differences in medium viscosity significantly altered the mass transfer and mixing performance of the JLR.

Technological Advances in Winery Wastewater Treatment: A Comprehensive Review

“…However, if homogenization is not adequate, the selectivity of the reaction is reduced. Therefore, the balance between mixing and mass transfer in JLR's is a crucial design aspect (Weber et al, 2019). FIGURE 3.…”

Circulating jet for enhancing the mass transfer in a gas–liquid stirred tank reactor

“…Jet aeration can be used to overcome the mass transfer limitation of stirred bioreactors. Compared with STR, jet loop reactor increases the oxygen transfer rate by 200%, increases the mass transfer rate by 67%, and increases the maximum space–time output by 40% 22–24 . However, the bubble size distribution in JLR is not uniform, and it is not suitable for oxidation reactions that are easy to crystallize 25…”