Oxygen transfer and mixing in mechanically agitated airlift bioreactors

Chisti, Yusuf; Jäuregui‐Haza, Ulises

doi:10.1016/s1369-703x(01)00174-7

Cited by 152 publications

(97 citation statements)

References 26 publications

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“…), and the dissipated energy in the fluid, which depends on the airflow rate, the stirrer speed, etc. Therefore, composition and rheological properties of the medium changing with time have an important effect on mass transfer rate (Montes et al 1999;Chisti et al 2002). Thus the coefficient (k L a) plays an important role in design, scale-up and economy of the process.…”

mentioning

confidence: 99%

Oxygen mass transfer studies on batch cultivation of P. aeruginosa in a biocalorimeter

Sivaprakasam¹,

Surianarayanan²,

Swaminathan³

2008

Electron. J. Biotechnol.

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Abbreviations: DO: dissolved oxygen OTR: oxygen transfer rate OUR: oxygen uptake rateIn the present work volumetric mass transfer coefficient (k L a) was investigated during batch cultivations of Pseudomonas aeruginosa on a nutrient media. The effects of process variables (viz. impeller speed, oxygen flow and geometry of impeller) on the volumetric mass transfer coefficient of oxygen, k L a, in a biocalorimeter (Bio-RC1) was investigated and reported in this research work. The experimental data have been analyzed employing MATLAB to obtain the influences of the process parameters on k L a. An attempt was made to correlate volumetric mass transfer coefficient with metabolic heat production rate at optimized process conditions. The correlation reported in this work would be useful to control and scale up of bioprocesses.

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mentioning

confidence: 99%

Oxygen mass transfer studies on batch cultivation of P. aeruginosa in a biocalorimeter

Sivaprakasam¹,

Surianarayanan²,

Swaminathan³

2008

Electron. J. Biotechnol.

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“…The power input due to mechanical agitation was calculated using the power number (N p ), versus the impeller Reynolds number (Re) [3].…”

Section: Bubble Sizementioning

confidence: 99%

“…Airlift bioreactors are devices characterized by the absence of mechanical agitation, and by the large height to diameter ratio, which contribute to their low cost of both construction and operation, in addition to presenting fewer problems in relation to the coalescence of bubbles. Furthermore, these reactors present a main disadvantage in the low gas-liquid mass transfer rates, when employing non-Newtonian highly viscous mediums; thus, compromising its performance [1]- [3], in addition to problems related to the insufficient homogenization of the cell cultures when applied on a pre-or industrial scale, being unsuitable for high density biomass cellular concentrations higher than 30 g dw.L -1 ; since the mixture low efficiency can lead to limitations in the homogenization of the medium, and in the oxygen transfer [4]. Aerated mechanically stirred tank bioreactors are widely used in industrial settings.…”

Section: Introductionmentioning

confidence: 99%

“…Pollard et al, [7] by using an impeller close to the bottom of the draft tube of an airlift bioreactor, were able to increase by 45% the productivity of the erythromycin antibiotic, when compared with a standard airlift bioreactor. Chisti and Jauregui-Haza [3] compared the mixture and oxygen transfer in a standard airlift bioreactor with two mechanical agitators; the first located near the center and another at the end of the draft tube. According to these authors, the use of axial flow impeller in the downcomer increased circulation of the liquid, the mixture, and the gas-liquid transfer, when compared to a standard airlift.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic and Mass Transfer Study in a Mechanically Stirred Hybrid Airlift Bioreactor Based on Impeller Type

Jesus¹,

Santana²,

Filho³

2014

IJCEA

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Abstract-The analysis of the influence by the impeller type in a stirred hybrid airlift bioreactor was performed in relation to the gas holdup, and mass transfer. The comparative study was performed using three-bladed marine and Lightnin A310 (axial flow impellers), and six-bladed Rusthon turbine and six-bladed Smith turbine (radial flow impellers). The experiments were conducted using distilled water at 25 0 C and a constant rotation velocity of 800 rpm, as well as in the absence of agitation (airlift mode); the superficial gas velocity varied from 0.0157 to 0.0262 ms -1 . The gas holdup and oxygen transfer coefficient was higher with the use of radial impellers; however, the mechanical power input required while using radial impellers is 730-1400% higher than with axial impellers.Index Terms-Axial Impeller, hydrodynamics, mass transfer, radial impeller, stirred airlift bioreactor.

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“…The k L a was calculated from the slope of the increasing dissolved oxygen concentration (Chisti & Jauregui-Haza 2002).…”

Section: Microorganismsmentioning

confidence: 99%

Optimisation of lab-scale continuous alcohol-free beer production

Lehnert¹,

Novák²,

Macieira³

et al. 2009

Czech J. Food Sci.

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Lehnert R., Novák P., Macieira F., Kuřec M., Teixeira J.A., Branyik T. (2009): Optimisation of labscale continuous alcohol-free beer production. Czech J. Food Sci., 27: 267-275.In order to study the formation and conversion of the most important flavour compounds, the real wort used in alcohol-free beer fermentation was mimicked by a complex model medium containing glucose, yeast extract, and selected aldehydes. The fermentation experiments were carried out in a continuously operating gas-lift reactor with brewing yeast immobilised on spent grains (brewing by-product). During the continuous experiment, parameters such as oxygen supply, residence time (Rt), and temperature (T) were varied to find the optimal conditions for the alcohol-free beer production. The formation of ethanol, higher alcohols (HA), esters (ES), as well as the reduction of aldehydes and consumption of glucose were observed. The results suggest that the process parameters represent a powerful tool in controlling the degree of fermentation and flavour formation brought about by immobilised biocatalyst. Subsequently, the optimised process parameters were used to produce real alcohol-free beer during continuous fermentation. The final product was compared with batch fermented alcohol-free beers using the methods of instrumental and sensorial analysis.

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Oxygen transfer and mixing in mechanically agitated airlift bioreactors

Cited by 152 publications

References 26 publications

Oxygen mass transfer studies on batch cultivation of P. aeruginosa in a biocalorimeter

Oxygen mass transfer studies on batch cultivation of P. aeruginosa in a biocalorimeter

Hydrodynamic and Mass Transfer Study in a Mechanically Stirred Hybrid Airlift Bioreactor Based on Impeller Type

Optimisation of lab-scale continuous alcohol-free beer production

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