Mixing studies in an unbaffled bioreactor using a computational model corroborated with in-situ Raman and imaging analyses

Mixing studies in an unbaffled bioreactor using a computational model corroborated with in-situ Raman and imaging analyses

Chemical Engineering Journal Advances

10.1016/j.ceja.2021.100232

http://dx.doi.org/10.1016/j.ceja.2021.100232

Vasudevan Vivek, Fitriani Nur Eka, Wee Chew

17 December 2021

Vivek, V., Eka, F. N., & Chew, W. (2022). Mixing studies in an unbaffled bioreactor using a computational model corroborated with in-situ Raman and imaging analyses. Chemical Engineering Journal Advances, 9, 100232. https://doi.org/10.1016/j.ceja.2021.100232

A computational model of an unbaffled 10 L bioreactor fitted with a unique serpentine tubing structure and two standard six-blade Rushton impellers was developed using Reynolds Averaged Navier-Stokes (RANS) turbulence models (standard k-ε and k-ω SST) and multiple reference frame (MRF) CFD modeling. Flow and mixing time simulations were validated with literature findings for baffled stirred tanks ranging from laboratory to commercial scales, viz. 5 L, 38 L, 22 m3 and 98 m3. Global quantities such as power number (Np), impeller flow number (NQ) and single-phase mixing times (t95) were verified with literature values. Flow and mixing simulations in the 10 L bioreactor were performed in full domain and a reduced 60◦ domain models. The reduced 60◦ domain model was selected for calculating mixing times at stirrer speeds from 50 to 500 rpm and fluid viscosities of 1 to 6 cP. This viscosity range corresponds to a typical high cell density E. coli fermentation run. For stirrer speeds more than 150 rpm in the 10 L bioreactor (Re > 3000), the mixing pattern in such high-density cultures could be reliably simulated with the standard k-ε model. Mixing time simulations in the 10 L bioreactor were validated against tracer mixing experiments using an inert red dye with HD video recording and inline Raman spectroscopy. Analyses of video images, univariate calculations and multivariate chemometrics on Raman data yielded experimental mixing times to compare with simulation results at four distinct spatial positions in the unbaffled 10 L bioreactor.

Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

This research / project is supported by the Agency for Science, Technology and Research (A*STAR) - IAF-PP: BioTrans Phase 3 Programme
Grant Reference no. : H20H6a0028

https://oar.a-star.edu.sg/communities-collections/articles/20129

2666-8211

Singapore Institute of Food and Biotechnology Innovation

https://doi.org/10.1016/j.ceja.2021.100232