Airlift bioreactor for biological applications with microbubble mediated transport processes
Airlift bioreactor for biological applications with microbubble mediated transport processes
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DOI：
10.1016/j.ces.2015.06.032
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发表时间：
2015-12-01
影响因子：
4.7
通讯作者：
Zimmerman, William B.
中科院分区：
文献类型：
--
作者：
AL-Mashhadani, Mahmood K. H.;Wilkinson, Stephen J.;Zimmerman, William B.
气升式生物反应器可以为搅拌罐提供有吸引力的替代方案，特别是对于具有气态反应物或产物的生物过程。然而，它们常常容易受到气液传质和液相混合不良的限制，特别是当它们在高细胞密度下运行时。在这项工作中，我们使用CFD建模来表明，由流体振荡产生的微泡可以提供一种有效的、低能量的手段，以实现高传质界面面积和改善混合液体循环。结果表明，当微泡直径超过200μm时，相当于反应器总体积约60%的“降液管”区域没有气泡。结果还表明，微泡的使用不仅增加了表面积与体积之比，而且还通过增加导流管周围的液体速度循环来提高混合效率。此外，由于与浮力相比更大的向下阻力，微气泡向下渗透到降液管中的深度随着气泡尺寸的减小而增加。模拟结果表明，随着扩散器位置高度的增加，死区体积增大。因此，我们假设由于扩散器位置不当而导致的气泡分布不良可能会对本工作中使用的生物反应器的性能产生明显的有害影响。 (C) 2015 年作者。由爱思唯尔有限公司出版
Airlift 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 mu m, 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. (C) 2015 The Authors. Published by Elsevier Ltd.