Enhanced Mass Transfer in Microbubble Driven  Airlift Bioreactor for Microalgal Culture

Ying, Kezhen; Al-Mashhadani, Mahmood K. H.; Hanotu, James; Gilmour, D. James; Zimmerman, William B.

doi:10.4236/eng.2013.59088

Cited by 33 publications

(27 citation statements)

References 14 publications

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“…The multiphase mass transfer from gases to liquids significantly improves when microbubbles are used as they provide a high surface to volume ratio. 36 There are a number of ways to produce microbubbles including supersaturated liquid release through a specially designed nozzle 37 and ultrasound. 38 However, these methods are highly energy intensive and would increase the cost of biofuel production.…”

Section: Microbubbles For Enhanced Mass Transfer and Mixingmentioning

confidence: 99%

Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass

et al. 2018

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A novel lignocellulosic biomass pretreatment reactor has been designed and tested to investigate pretreatment efficacy of miscanthus grass. The reactor was designed to optimize the transfer of highly oxidative species produced by dielectric barrier discharge plasma to the liquid phase immediately after generation, by arranging close proximity of the plasma to the gas-liquid interface of microbubbles. The reactor produced a range of reactive oxygen species and reactive nitrogen species, and the rate of production depended on the power source duty cycle and the temperature of the plasma. Ozone and other oxidative species were dispersed efficiently using energy efficient microbubbles produced by fluidic oscillations. A 5% (w/w) miscanthus suspension pretreated for 3 h at 10% duty cycle yielded 0.5% acid soluble lignin release and 26% sugar release post hydrolysis with accelerated pretreatment toward the latter stages of the treatment demonstrating the potential of this approach as an alternative pretreatment method.

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Section: Microbubbles For Enhanced Mass Transfer and Mixingmentioning

confidence: 99%

Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass

et al. 2018

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“…Because the flow rates of the systems were orders of magnitude apart and increasing flow rate increases K L a for most devices, the K L a values were normalized by taking a ratio of the K L a multiplied by the volume of liquid (constant) and divided by the flow rate, making this value dimensionless (Prasad and Ramanujam, 2009;Ying et al, 2013). Previous modeling studies have normalized the K L a with the flow rate and volume (Badino et al, 2001).…”

Section: Volumetric Mass Transfer Coefficient (K L A)mentioning

confidence: 99%

Microfluidic bubbler facilitates near complete mass transfer for sustainable multiphase and microbial processing

Baker

Crivellari

Gagnon

et al. 2016

Biotech & Bioengineering

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A microfluidic device (channels <70 μm) was utilized to create micro-scale bubbles to significantly increase mass transfer efficiency at low flow rates. The convergence of one gas and two liquid channels at a Y-junction generates bubbles via cyclic changes in pressure. At low flow rates, the bubbles had an average diameter of 110 μm, corresponding to a volumetric mass transfer KL a of 1.43 h(-1) . Values of KL a normalized per flow rate showed that the microbubbler had a 100-fold increased transfer efficiency compared to four other commonly used bubblers. The calculated percentage of oxygen transferred was approximately 90%, which was consistent with a separate off-gas analysis. The improved mass transfer was also tested in an algae bioreactor in which the microbubbler absorbed approximately 90% of the CO2 feed compared to 2% in the culture with an alternative needle bubbling method. The microbubbler yielded a cell density 82% of the cell density for the alternative needle tip with an 800-fold lower flow rate (0.5 mL/min versus 400 mL/min) and a 700-fold higher ratio of biomass to fed carbon dioxide. The application of microfluidics may transform interfacial processing in order to increase mass transfer efficiencies, minimize gas feeding, and provide for more sustainable multiphase processes. Biotechnol. Bioeng. 2016;113: 1924-1933. © 2016 Wiley Periodicals, Inc.

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“…This has seen their widespread use in various biological processes, for example: biomass from yeast, vinegar, bacteria, etc. These advantages can be considerably further improved by equipping the ALRs with a fluidic oscillator for generating micro-bubbles which, compared to traditional stirred tanks, can dramatically increase the interfacial area between gas and liquid phases (Ying et al, 2014(Ying et al, , 2013a(Ying et al, , 2013bZimmerman et al, 2011aZimmerman et al, , 2011b.…”

Section: Introductionmentioning

confidence: 98%

Airlift bioreactor for biological applications with microbubble mediated transport processes

Al-Mashhadani

Wilkinson

Zimmerman

2015

Chemical Engineering Science

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Microbubbles increase the mixing efficiency in airlift bioreactors. Dispersal of gas phase throughout the ALR occurs with decreasing the bubble size. Phase slip velocity decreases with smaller bubble size as gas rise rate decreases. a b s t r a c tAirlift bioreactors can provide an attractive alternative to stirred tanks, particularly for bioprocesses with gaseous reactants or products. Frequently, however, they are susceptible to being limited by gas-liquid mass transfer and by poor mixing of the liquid phase, particularly when they are operating at high cell densities. In this work we use CFD modelling to show that microbubbles generated by fluidic oscillation can provide an effective, low energy means of achieving high interfacial area for mass transfer and improved liquid circulation for mixing.The results show that when the diameter of the microbubbles exceeded 200 mm, the "downcomer" region, which is equivalent to about 60% of overall volume of the reactor, is free from gas bubbles. The results also demonstrate that the use of microbubbles not only increases surface area to volume ratio, but also increases mixing efficiency through increasing the liquid velocity circulation around the draft tube. In addition, the depth of downward penetration of the microbubbles into the downcomer increases with decreasing bubbles size due to a greater downward drag force compared to the buoyancy force. The simulated results indicate that the volume of dead zone increases as the height of diffuser location is increased. We therefore hypothesise that poor gas bubble distribution due to the improper location of the diffuser may have a markedly deleterious effect on the performance of the bioreactor used in this work.

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Enhanced Mass Transfer in Microbubble Driven Airlift Bioreactor for Microalgal Culture

Cited by 33 publications

References 14 publications

Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass

Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass

Microfluidic bubbler facilitates near complete mass transfer for sustainable multiphase and microbial processing

Airlift bioreactor for biological applications with microbubble mediated transport processes

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