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Liquid residence time distributions in immobilized cell bioreactors
Author(s) -
Swaine Donald E.,
Daugulis Andrew J.
Publication year - 1989
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260330514
Subject(s) - bioreactor , residence time distribution , yeast , zymomonas mobilis , saccharomyces cerevisiae , chemistry , volumetric flow rate , chromatography , packed bed , chemical engineering , mixing (physics) , scale up , residence time (fluid dynamics) , adsorption , fermentation , ethanol fuel , biochemistry , thermodynamics , mineralogy , organic chemistry , inclusion (mineral) , physics , quantum mechanics , classical mechanics , engineering , geotechnical engineering
Previous work has demonstrated that high ethanol productivities can be achieved using yeast or bacterial cells adsorbed onto the surface of ion exchange resin in vertical packed bed bioreactors. The present work quantitatively characterizes the overall degree of backmixing in such reactors at two scales of operation: 2.0 and 8.0 L. Stimulus‐response experiments, using two solvents (2,3‐butanediol and 2‐ethoxyethanol) as tracers, were performed to measure the liquid phase residence time distribution (RTD) during continuous ethanol fermentations using the yeast Saccharomyces cerevisiae and the bacterium Zymomonas mobilis at the 2‐L scale, and with S. cerevisiae at the 8‐L scale. In order to separately determine the effects of liquid flow rate and gas evolution on the degree of mixing, stimulus–response experiments were also performed in the systems without microbial cells present. The evolution of CO 2 was found to dramatically increase the extent of mixing; however, the tanks‐in‐series model for non‐ideal flow represented the systems adequately. The packed beds were equivalent to over 70 tanks‐in‐series during abiotic operation while during fermentations, with similar liquid flow rates, they ranged in equivalence from 35 to 15 tanks‐in‐series. This increased knowledge of the overall degree of mixing in packed bed, immobilized cell bioreactors will allow for more accurate kinetic modelling and efficient scale up of the process.