Applied Biochemistry and Biotechnology

, Volume 39, Issue 1, pp 455–466 | Cite as

Enhancement of the oxygen transfer in a circulating three-phase fluidized bed bioreactor

  • Eduardo D. Dabdoub Paz
  • Maria Helena A. Santana
  • Silvia Y. Eguchi
Session 4 Bioengineering Research


The addition of α-alumina to the aqueous solution of sodium alginate for imobilization of viable cells allows the production of denser particles than the ones obtained with sodium alginate alone. This biocatalyst was used in the continuous oxidation of ethanol to acetic acid, by a strain ofAcetobacter isolated from an ethanol plant. The continuous fermentation was carried out in a circulating three-phase fluidized bed bioreactor.

Denser particles allow a greater oxygen transfer, resulting in increased volumetric production rate of acetic acid, because oxygen is usually the limiting factor of this process. The performance of the biocatalyst was analyzed in terms of respiration rate, oxygen diffusivity, volumetric mass-transfer coefficient, and global productivity.

Index Entries

Immobilized cells mass transfer Acetobacter 



Saturated dissolved oxygen concentration in liquid medium (kmol m−3)


Dissolved oxygen concentration in liquid medium, (kmol m−3)

CHAc1, CHAc2

Initial and final acetic acid concentrations (kmol/mL)


Dilution rate, h−1


Oxygen effective intraparticle diffusion coefficient, (m2/s)


Gravitional constant (m2/s)


Mass-transfer coefficient (m/s)


Volumetric mass-transfer coefficient (s−1)


Michaelis-Menten constant (kmol/m−3)


Total acetic acid production rate (g/L·h)


Specific respiration rate (kmol/kg[dry wt]h)

Qo2 actual

Actual specific respiration rate of immobilized cells for 1.7 mm diameter particles (kmol/kg[dry wt]h)

Qo2 free of diffusion limitations

Specific respiration rat3, in the absence of diffusion resistance, of immobilized cells for 0.1 mm diameter particles (kmol/kg[dry wt]h)


Particle radius (m)


Total cell concentration (g/L)


Saturation parameter


Liquid holdup


Thiele modulus


Effectiveness factor


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Copyright information

© Humana Press Inc. 1993

Authors and Affiliations

  • Eduardo D. Dabdoub Paz
    • 1
  • Maria Helena A. Santana
    • 1
  • Silvia Y. Eguchi
    • 2
  1. 1.Laboratory of Development of Biotechnological Process, Chemical Engineering SchoolUNICAMPCampinasBrazil
  2. 2.Tropical Culture CollectionFundacao Tropical de Pesquisas e Tecnologia “Andre Tosello”CampinasBrazil

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