Jet aeration as alternative to overcome mass transfer limitation of stirred bioreactors

Weber, Sebastian; Schaepe, Sebastian; Kopf, Michael-Helmut; Freyer, Stephan; Dietzsch, Christian

doi:10.1002/cite.201855260

Cited by 4 publications

(7 citation statements)

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“…Secondly, the new jet aeration scheme can significantly reduce the pump pressure moving the fermentation medium through reactor loop. In standard scheme, the pump pressure has to be at least 3 bars in order to ensure air intake (Weber et al, 2018a;Moresi et al, 1983); for the jet aeration based on new scheme, the sufficient pump pressure is 0.3 bar. Such decrease in pressure not only leads to a decrease in the pump electric power but also helps to reduce shear loads on the impeller cells.…”

Section: Methodsmentioning

confidence: 99%

“…The mixture, saturated with air, can be either sprayed onto the medium surface in reactor or supplied in doses (Warmeling et al, 2016;Meyer and Charles, 1982). The aeration rate in jet loop bioreactors may vary over a wide range from 0.25... to 2.0 vvm (Ughetti et al, 2018;Weber et al, 2018a;Moresi et al, 1983). Furthermore, due to the mixing of media in ejector (and not in apparatus), a more uniform distribution of air in medium and its greater oxygen saturation are ensured (Weber et al, 2018b).…”

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confidence: 99%

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Development and Research of New Media Jet Aeration Scheme in a Loop Bioreactor Producing Microbiological Products

Yaroshevsky

Krutyakova

Belchenko

et al. 2021

Acta Technologica Agriculturae

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Jet aeration loop reactors are widely used in the chemical industry due to their high mixing intensity, possibility of significant saturation of medium with gases, and simplicity of scaling the processes when passing from laboratory equipment to industrial designs. However, to ensure the necessary amount of air in standard jet aeration schemes with ejectors, high pressure of the medium (up to 6 bars) is required in the reactor loop. This paper presents a newly developed scheme of jet aeration, based on mixing the pressure flows of medium and air supplied to the ejector by individual blowers. Experiment results of the new water aeration scheme showed that, for the formation of suspended matter in the ejector with an air content of 2–20 l per 1 l of water, a pressure of 0.3 bar in the reactor loop at an air pressure of 1 bar is sufficient. This allows usage of low-pressure pump and compressor, which form the basis for the energy consumption reduction and creates prerequisites for lowering the shear loads on a crop. The medium aeration rate during experiments was 0.220–0.266 vvm. It was found that, for each mode of joint operation of pump and compressor, it is possible to maintain a constant aeration rate, which is not significantly affected by the flowrate regulation of medium in loop.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Development and Research of New Media Jet Aeration Scheme in a Loop Bioreactor Producing Microbiological Products

Yaroshevsky

Krutyakova

Belchenko

et al. 2021

Acta Technologica Agriculturae

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show abstract

“…Subsequently, the aeration was started and the increasing oxygen concentration (c O2 ) was measured by an optical oxygen sensor. The k L a values were determined from the respective step response between 20 and 80% of the maximum dissolved oxygen concentration (c O2 * ) (Equation ).

{normalk}_{normalL} normala = \frac{ln (\frac{{normalc}_{O 2}^{*} - {normalc}_{O 2, 1}}{{normalc}_{O 2}^{*} - {normalc}_{O 2, 2}})}{{normalt}_{2} - {normalt}_{1}}

…”

Section: Methodsmentioning

confidence: 99%

“…In recent studies, an increase in mass transfer up to ∼200% and therefore higher productivities were achieved in jet loop Abbreviations: CMC, Carboxy methyl cellulose; JLR, Jet aerated loop reactor; OTR, Oxygen transfer rate; STR, Stirred tank reactor reactors (JLRs) compared to stirred tank reactors (STRs) [7,8]. Surprisingly in some cases the concentration of the anaerobic and overflow metabolite acetate was already increasing for cultivation at strictly aerobic conditions [9]. Therefore, the presence of oxygen-and substrate gradients within the JLR was considered as a possible reason for the observed acetate formation.…”

Section: Introductionmentioning

confidence: 99%

Monitoring gradient formation in a jet aerated bioreactor

Weber

Schaepe

Freyer

et al. 2018

Engineering in Life Sciences

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Jet aerated loop reactors (JLRs) provide high mass transfer coefficients (kLa) and can be used for the intensification of mass transfer limited reactions. The jet loop reactor achieves higher kLa values than a stirred tank reactor (STR). The improvement relies on significantly higher local power inputs (∼104) than those obtainable with the STR. Operation at high local turnover rates requires efficient macromixing, otherwise reactor inhomogeneities might occur. If sufficient homogenization is not achieved, the selectivity of the reaction and the respective yields are decreased. Therefore, the balance between mixing and mass transfer in jet loop reactors is a critical design aspect. Monitoring the dissolved oxygen levels during the turnover of a steady sodium sulfite feed implied the abundance of gradients in the JLR. Prolonged mixing times at identical power input and aeration rates (∼100%) were identified for the JLR in comparison to the STR. The insertion of a draft tube to the JLR led to a more homogenous dissolved oxygen distribution, but unfortunately a reduction of mixing time was not achieved. In case of increased medium viscosities as they may arise in high cell density cultivations, no gradient formation was detected. However, differences in medium viscosity significantly altered the mass transfer and mixing performance of the JLR.

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“…A previous study showed that a higher mass transfer per power input could be generated with a JLR compared to an aerated STR. As a result, a higher productivity was achieved [21]. However, the influence of the mode of nozzle operation on mass transfer performance and efficiency was not considered so far.…”

Section: Alternative Reactors For Aerobic Bioprocessesmentioning

confidence: 99%

Impact of nozzle operation on mass transfer in jet aerated loop reactors. Characterization and comparison to an aerated stirred tank reactor

Weber

Schaepe

Freyer

et al. 2018

Engineering in Life Sciences

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The impact of mass transfer on productivity can become a crucial aspect in the fermentative production of bulk chemicals. For highly aerobic bioprocesses the oxygen transfer rate (OTR) and productivity are coupled. The achievable space time yields can often be correlated to the mass transfer performance of the respective bioreactor. The oxygen mass transfer capability of a jet aerated loop reactor is discussed in terms of the volumetric oxygen mass transfer coefficient kLa [h−1] and the energetic oxygen transfer efficiency E [kgO2 kW−1 h−1]. The jet aerated loop reactor (JLR) is compared to the frequently deployed aerated stirred tank reactor. In jet aerated reactors high local power densities in the mixing zone allow higher mass transfer rates, compared to aerated stirred tank reactors. When both reactors are operated at identical volumetric power input and aeration rates, local kLa values up to 1.5 times higher are possible with the JLR. High dispersion efficiencies in the JLR can be maintained even if the nozzle is supplied with pressurized gas. For increased oxygen demands (above 120 mmol L−1 h−1) improved energetic oxygen transfer efficiencies of up to 100 % were found for a JLR compared to an aerated stirred tank reactor operating with Rushton turbines.

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Jet aeration as alternative to overcome mass transfer limitation of stirred bioreactors

Cited by 4 publications

References 0 publications

Development and Research of New Media Jet Aeration Scheme in a Loop Bioreactor Producing Microbiological Products

Development and Research of New Media Jet Aeration Scheme in a Loop Bioreactor Producing Microbiological Products

Monitoring gradient formation in a jet aerated bioreactor

Impact of nozzle operation on mass transfer in jet aerated loop reactors. Characterization and comparison to an aerated stirred tank reactor

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