Biotechnology and Bioprocess Engineering

, Volume 11, Issue 3, pp 245–250 | Cite as

Effects of hydrocarbon additions on gas-liquid mass transfer coefficients in biphasic bioreactors

  • Teresa Lopes da Silva
  • Vitor Calado
  • Nadia Silva
  • Rui L. Mendes
  • Sebastião S. Alves
  • Jorge M. T. Vasconcelos
  • Alberto Reis


The effects of aliphatic hydrocarbons (n-hexadecane andn-dodecane) on the volumetric oxygen mass transfer coefficient (k L a) were studied in flat alveolar airlift reactor and continuous stirred tank reactors (CSTRs). In the flat alveolar airlift reactor, high aeration rates (>2 vvm) were required in order to obtain efficient organic-aqueous phase dispersion and reliablek L a measurements. Addition of 1% (v/v)n-hexadecane orn-dodecane increased thek l a 1.55-and 1.33-fold, respectively, compared to the control (superficial velocity: 25.8×10−3 m/s, sparger orifice diameter: 0.5 mm). Analysis of the gas-liquid interfacial areaa and the liquid film mass transfer coefficientk L suggests that the observedk L a increase was a function of the media's liquid film mass transfer. Addition of 1% (v/v)n-hexadecane orn-dodecane to analogous setups using CSTRs led to ak L a increase by a factor of 1.68 and 1.36, respectively (superficial velocity: 2.1×10−3 m/s, stirring rate: 250 rpm). These results propose that low-concentration addition of oxygen-vectors to aerobic microbial cultures has additional benefit relative to incubation in purely aqueous media.


flat alveolar airlift bioreactor CSTR oxygen-vector kLa, dodecane hexadecane 



specific interfacial area (1/m)


oxygen saturation concentration of the aqueous phase (g/L)


dissolved oxygen concentration of the aqueous phase (g/L)


Sauter mean bubble diameter (m)


diameter of the volume-equivalent sphere (m)


impeller diameter (m)


bubble major axis in two-dimensional projection (m)


bubble minor axis in two-dimensional projection (m)


liquid film mass transfer coefficient (m/h)


k L in the presence of an oxygen-vector (organic phase) (m/h)


k L in the absence of an oxygen-vector (aqueous phase) (m/h)


volumetric mass transfer coefficient (1/h)


k L a in the presence of an oxygen-vector (organic phase) (1/h)


k L a in the absence of an oxygen-vector (aqueous phase) (1/h)


impeller speed (1/s)


power (W)


time (h)


liquid volume (m3)

Greek symbols


sparger orifice diameter (mm)


gas hold up (dimensionless)


superficial gas velocity (m/s)


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Copyright information

© The Korean Society for Biotechnology and Bioengineering 2006

Authors and Affiliations

  • Teresa Lopes da Silva
    • 1
  • Vitor Calado
    • 1
  • Nadia Silva
    • 1
  • Rui L. Mendes
    • 2
  • Sebastião S. Alves
    • 3
  • Jorge M. T. Vasconcelos
    • 3
  • Alberto Reis
    • 1
  1. 1.Instituto Nacional de Engenharia, Tecnologia e Inovação, Departamento de BiotecnologiaUnidade de Bioengenharia e BioprocessosLisboaPortugal
  2. 2.Instituto Nacional de Engenharia, Tecnologia e Inovação, Departamento de Energias RenováveisUnidade de BiomassaLisboaPortugal
  3. 3.Instituto Superior Técnico, Departamento de Engenharia Química e BiológicaCentro de Engenharia Biológica e QuímicaLisboaPortugal

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