Effect of fluid rheological properties on mass transfer in a bioreactor

Li, Guoqing; Qiu, Hong‐Wei; Cai, Zhaoling; Yang, Shou-Zhi

doi:10.1002/jctb.280620412

Cited by 31 publications

(11 citation statements)

References 8 publications

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“…Thus, the conventional method of oxygen supply is inadequate for this cultivation. It should be noted that the bioreactor k L a for the conditions employed in the conventional cultivation was 28.8 h −1 , which compares well with 21.6 h −1 , obtained at a higher rpm (450 rpm), in another stirred tank used for xanthan gum studies reported in the literature (Li et al, 1995). Thus, the k L a employed was a reasonable value.…”

Section: Inadequacy Of Aerationsupporting

confidence: 78%

Oxygen supply without gas–liquid film resistance toXanthomonas campestris cultivation

Sriram

Rao

Suresh

et al. 1998

Biotechnol. Bioeng.

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Alternative methods of oxygen supply are of crucial importance, especially in viscous fermentations and shear‐sensitive fermentations. A method of oxygen supply that completely eliminates the gas–liquid transport resistance has been presented. The method involves a need‐based liquid‐phase decomposition of hydrogen peroxide to provide the necessary oxygen. When Xanthomonas campestris was cultivated (viscous cultivation) using this method of oxygen supply, dissolved oxygen (DO) levels were maintained above the setpoint of 50% throughout the cultivation, whereas the conventional cultivation was able to meet culture oxygen demand only for about 6 h in a 72‐h fermentation. Furthermore, the maximum specific growth rate and xanthan yields in the novel cultivation were 89% and 169%, respectively, of those obtained in conventional cultivation. A mathematical model was also developed to simulate and predict results in fermentations employing the presented methodology. In addition, studies with HOCl pretreatments indicated that monofunctional catalase may be responsible for the decomposition of H2O2 supplied externally to cells; HOCl pretreatments also increased the tolerance of cells to H2O2. The decomposition kinetics of externally supplied H2O2 was Michaelis–Menten in nature with vmax = 1.196 × 10−6M s−1 and Km = 0.21 mM. The catalase concentration was estimated to be 3.4 × 10−10 mol/g of cells. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:714–723, 1988.

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Section: Inadequacy Of Aerationsupporting

confidence: 78%

Oxygen supply without gas–liquid film resistance toXanthomonas campestris cultivation

Sriram

Rao

Suresh

et al. 1998

Biotechnol. Bioeng.

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“…There could not be a proper correlation drawn with viscosity until first 6 h, but later an increase in viscosity contributed towards decrease in k L a by offering oxygen transfer resistance. These results were in direct concordance with the microbial production of polysaccharides where the increase in viscosity decreased k L a by decreasing gasliquid specific surface area [21].…”

Section: Th Sludge Without Tween 80supporting

confidence: 68%

Impact of Tween 80 during Bacillus thuringiensis fermentation of wastewater sludges

Brar

Verma

Barnabé

et al. 2005

Process Biochemistry

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“…Similar observations can be made for the properties needed to precisely predict transport of metabolites, nutrients, or CO 2 . So far, most studies are based on experimental investigations, which are usually interpreted with simple theoretical models 3, 4, 8–11. First‐principles methods to predict mass‐transfer coefficients, transport rates, and other parameters in non‐Newtonian fluids have not been reported so far.…”

Section: Introductionmentioning

confidence: 99%

Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

2007

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In this work, high-resolution 2-D numerical simulations were performed on the motion of deformable bubbles in non-Newtonian fluids and the associated mass transfer. For that purpose, we have implemented a semi-Lagrangian advection scheme and improved the fluid dynamic calculation by the usage of implicit algorithms. Non-Newtonian fluids are described by generalized Newtonian as well as viscoelastic model fluids. As shear-thinning model we use a Power-Law and a Carreau-Yasuda model, the viscoelastic fluid simulations are based on an Upper-Convected Maxwell model combined with a recently introduced model for the evolution of the effective shear rate. The mathematical challenges arising from the hyperbolic nature of the resulting set of equations are addressed by inclusion of artificial diffusion in the stress equation. In our work, it was found that shear thinning effects have impact on collision rates, and therefore, may influence coalescence of bubbles in non-Newtonian liquids. Furthermore, for the first time, concentration fields of dissolved gas in viscoelastic fluids are presented. The study shows that the fluid elasticity plays a major role for bubble rise velocity, and therefore, mass transfer. As the wake dynamics differ significantly from that in Newtonian liquids, abnormal mixing characteristics can be expected in the bubbly flow of viscoelastic fluids. 2007 American Institute of Chemical Engineers AIChE J, 53: [1861][1862][1863][1864][1865][1866][1867][1868][1869][1870][1871][1872][1873][1874][1875][1876][1877][1878] 2007 Keywords: numerical simulation, bubbles, non-Newtonian liquids, mass transfer IntroductionBecause of persistent uncertainties in the underlying models and system properties, the scale-up of bioreactors remains a challenging problem. For example, the rheology of media in bioreactors is non-Newtonian in most cases. [1][2][3][4][5][6][7][8] However, details of the non-Newtonian fluid characteristics, such as viscoelasticity or the tendency for shear thinning, are frequently unknown or neglected. Furthermore, in contrast to Newtonian media, there is a lack of general correlations for mass and heat transfer rates, which are needed for the prediction of oxygen supply and heat removal. Similar observations can be made for the properties needed to precisely predict transport of metabolites, nutrients, or CO 2 . So far, most studies are based on experimental investigations, which are usually interpreted with simple theoretical models. 3,4,[8][9][10][11] principles methods to predict mass-transfer coefficients, transport rates, and other parameters in non-Newtonian fluids have not been reported so far. Local mass transfer is not the only micro-effect of central importance in the design of bioreactors. Knowledge of the localized forces, such as shear and normal stresses in the cell's microenvironment, is also a key for determining whether a bioreactor is suitable to handle sensitive biosystems.12 Subcritical shear stresses found in the hydrodynamic environment of large-scale reactors may redu...

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Effect of fluid rheological properties on mass transfer in a bioreactor

Cited by 31 publications

References 8 publications

Oxygen supply without gas–liquid film resistance toXanthomonas campestris cultivation

Oxygen supply without gas–liquid film resistance toXanthomonas campestris cultivation

Impact of Tween 80 during Bacillus thuringiensis fermentation of wastewater sludges

Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

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