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Insights into large‐scale cell‐culture reactors: II. Gas‐phase mixing and CO 2 stripping
Author(s) -
Sieblist Christian,
Hägeholz Oliver,
Aehle Mathias,
Jenzsch Marco,
Pohlscheidt Michael,
Lübbert Andreas
Publication year - 2011
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.201100153
Subject(s) - stripping (fiber) , mixing (physics) , gas phase , scale (ratio) , chemistry , phase (matter) , chemical engineering , materials science , physics , engineering , organic chemistry , quantum mechanics , composite material
Most discussions about stirred tank bioreactors for cell cultures focus on liquid‐phase motions and neglect the importance of the gas phase for mixing, power input and especially CO 2 stripping. Particularly in large production reactors, CO 2 removal from the culture is known to be a major problem. Here, we show that stripping is mainly affected by the change of the gas composition during the movement of the gas phase through the bioreactor from the sparger system towards the headspace. A mathematical model for CO 2 ‐stripping and O 2 ‐mass transfer is presented taking gas‐residence times into account. The gas phase is not moving through the reactor in form of a plug flow as often assumed. The model is validated by measurement data. Further measurement results are presented that show how the gas is partly recirculated by the impellers, thus increasing the gas‐residence time. The gas‐residence times can be measured easily with stimulus‐response techniques. The results offer further insights on the gas‐residence time distributions in stirred tank reactors.