Abstract
An approach to modify external loop airlift bioreactor is presented that examines its performance with respect to mass transfer. There are various designs of airlift fermenter [1]. In the proposed system [2] the riser has been replaced by a tube of irregular geometry, in the form of converging-diverging sections (CDT-ALF), so that better mass transfer may be obtained due to better liquid mixing caused by the bubble flow, pulsation effect and early transition to turbulence. Mass transfer characteristics of the modified airlift fermenter CDT-ALF were studied and compared with those of a conventional one, UT-ALF. Overall volumetric mass transfer coefficient,K L a, was determined by sulfite oxidation method.K L a was determined with respect toU G for differenth i. HigherK L a was always observed in CDT-ALF compared to that in UT-ALF under any operating condition ofh i andU G. If theK L a values are compared in both the systems under their optimum conditions ofh i andU G, CDT-ALF showed 122.5% higher values ofK L a compared to UT-ALF. However, when both the systems were operated at the lowest experimental conditions ofU G, thek L a in CDT-ALF was found to be 170% higher. In UT-ALF while with the decrease ofU G,k L a decreased, in CDT-ALF the reverse was observed i.e. at lowU G,K L a was higher. However with the increase ofh i,K L a decreased in both the systems. To predict volumetric mass transfer coefficientK L a, empirical correlations were developed by dimensional analysis for both the reactors. The correlations were experimentally verified to determine their reliability to predict mass transfer coefficient and the deviation was found within reasonable limit.
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Abbreviations
- ALF:
-
Airlift Fermenter
- UT-ALF:
-
Uniform Tube Airlift Fermenter
- CDT-ALF:
-
Converging-diverging Tube Airlift Fermenter
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Ghosh, T.K., Maiti, B.R. & Bhattacharyya, B.C. Studies on mass transfer characteristics of a modified airlift fermenter. Bioprocess Engineering 9, 239–244 (1993). https://doi.org/10.1007/BF01061528
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DOI: https://doi.org/10.1007/BF01061528