Particle back-transport and permeate flux behavior in crossflow membrane filters
Particle back-transport and permeate flux behavior in crossflow membrane filters
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DOI：
10.1021/es9605228
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发表时间：
1997-03-01
影响因子：
11.4
通讯作者：
Wiesner, MR
中科院分区：
文献类型：
--
作者：
Chellam, S;Wiesner, MR
通过对膜通道中颗粒停留时间分布的分析，阐明了膜过滤过程中颗粒迁移和胶体污染的机理。膜进料悬浮液和沉积的滤饼中的颗粒尺寸分布的比较提供了选择性颗粒在膜上的运输和积累的证据。这些数据支持了先前假设的最小颗粒从膜的回输作为粒径的函数。小颗粒的回输显然是由于布朗扩散，而较大的大胶体由正交动力学机制，如剪切诱导扩散控制。在所有情况下，在死端模式下测得的滤饼比电阻高于相应的进料悬浮液。此外，在横流下测得的滤饼比阻高于死端模式下测得的滤饼比阻。此外，膜上的颗粒沉积物的比电阻随剪切Fate而增加，并随初始渗透速率的增加而降低，这表明滤饼形态是确定渗透通量的重要参数。因此，流体动力学对滤饼阻力的影响需要建立一个全面的错流过滤模型，才能得到。
Particle residence time distributions in a membrane channel are interpreted to elucidate mechanisms of particle transport and colloidal fouling in membrane filtration. A comparison of particle size distributions in the membrane feed suspensions and deposited cakes provides evidence for selective particle transport and accumulation on membranes. These data support a previously hypothesized minimum in particle back-transport from the membrane as a function of particle size. The back-transport of smaller particles is apparently due to Brownian diffusion, while larger macrocolloids are controlled by an orthokinetic mechanism such as shear-induced diffusion. In all cases, cake specific resistances measured in the dead-end mode were higher than those of the corresponding feed suspensions. Also, cake specific resistances measured under a crossflow were higher than those in the dead-end mode. Further, the specific resistance of particle deposits on membranes increased with shear Fate and decreased as the initial permeation rate increased, suggesting that cake morphology is an important parameter in determining permeate flux. Thus, the effects of hydrodynamics on cake resistance needs to be established before a comprehensive model for crossflow filtration can be derived.