Hollow fiber membrane configuration

Figure 17 Typical hollow fiber membrane configuration for nitrogen.

Dagnew, M., Pickel, J., Parker, W., Seto, P. (2013). Anaerobic membrane bio-reactors for waste activated sludge digestion tubular versus hollow fiber membrane configurations. Environmental Progress and Sustainable Energy, 32, 598—604. 

Rgure 8. Frequently Used Membrane Types. A, B, C, and D are bulk liquid membrane, emulsion liquid membrane, supported liquid membrane, and dual module hollow fiber membrane configurations respectively. (Reproduced with permission from ref. 47. Copyright 1990 CRC Press.)... 

Figure 1. Different Types of Liquid Membranes BLM = Bulk Liquid Membrane ELM = Emulsion Liquid Membrane and SLM = Supported Liquid Membrane with a) Flat Membrane and b) Hollow Fiber Membrane Configurations. (F = feed solution M = membrane phase S = stripping solution)...

Nonselective membranes can assist enantioselective processes, providing essential nonchiral separation characteristics and thus making a chiral separation based on enantioselectivity outside the membrane technically and economically feasible. For this purpose several configurations can be applied (i) liquid-liquid extraction based on hollow-fiber membrane fractionation (ii) liquid- membrane fractionation and (iii) micellar-enhanced ultrafiltration (MEUF). 

The volume of the equipment for a given area requirement depends on the chosen membrane configuration. For example, spiral wound membranes have a typical packing density of around 800 m2-m 3, whereas the packing density for hollow fiber membranes is much higher, at around 6000 m2-m 3. 

Although several hepatocyte-based Ever support systems have been proposed, there is no current consensus on its eventual design configuration. The most devices used currently are based on conventional hollow fiber membranes, and there are many opportunities for bioengineers to design new bioreactors that will optimize device function, particularly with regard to oxygen and nutrient provision. 

By far, the most advanced technology in cnrrent nse is the hollow fiber techniqne. It has been reviewed extensively in the literature. Briefly, this configuration involves the cultivation of hepatocytes on the external surfaces of semipeimeable capillary hollow fiber membranes bundled together within a plastic shell. Nutrients and ultimately plasma from patient blood are circulated through the fibers. The cells in the capillaries provide hepatic function. In the current versions of this technology, cultured porcine hepatocytes are protected from the body s immune system by the semipermeable capillary membrane. 

Figure 4.17. Configurations of membrane modules using hollow-fiber membranes, (a) Membrane in sample (MIS). (b) Sample in membrane (SIM).

First commercial hollow-fiber membrane module developed by DuPont. This module configuration further increased the packing density of membrane modules. 

Microfiltration and UF membranes are available in tubular, spiral wound, and hollow fiber membrane module configurations. Tubular and spiral MF and UF modules are similar to RO tubular and spiral wound membrane modules described in Chapters 4.3.2 and 4.3.3. However, while the thickest feed spacer in a spiral RO module is 34-mil, UF and MF modules nominally have up to a 45-mil spacer due to the relatively high concentration of suspended solids these membranes are called upon to treat (TriSep Corporation offers a special 65-mil spacer for dairy applications). 

Hollow fiber membrane modules can be backwashed to remove foulants whereas tubular and most spiral configurations cannot be backwashed. Backwashing of traditional spiral-wound modules would break the glue lines holding the membrane leaves together or cause blistering and delamination of the membrane from the backing in both spiral and tubular modules (TriSep Corporation has recently developed a back-washable, spiral-wound module (SpiraSep—US patent 6,755,970), that is used in immersed systems see below). 

FIGURE 4.21 Hollow fiber membrane modules with different configurations. (From Pellegrino J., Sikdar S.K., Membrane Technology, Fundamentals of Bioremediation http //membranes.nist.gov/Bioremediation/fig pages/f5.html (accessed September 2004). With permission.)... 

The hollow fiber membranes are the optimum choice for gas separation modules due to their very high packing density (up to 30,000 m /m may be attained [1]). Figure 4.21 shows alternative configurations for such modules [108]. Modifications of this configuration exist, where possibility for introduction of sweep gas on permeate side is included, or fibers may be arranged transversal to the flow in order to minimize concentration polarization [109,110]. The hollow fiber membranes are usually asymmetric polymers, but composites also exist. Carbon molecular sieve membranes may easily be prepared as hollow fibers by pyrolysis. 

Chang S and Fane AG, Filtration of biomass with lab-scale submerged hollow fiber membrane module Effect of operational conditions and module configuration, J. Chem. Technol. Biotechnol. 2002 77 1030-2212. 

As one of the two common types of membrane modules, the hollow-fiber membrane module has shown excellent mass transfer performance due to its large surface area per unit volume (about 1000-3000ft2/ft3 for gas separation). In the modeling work, the WGS membrane reactor was configured to be a hollow-fiber membrane module with catalyst particles packed inside the fibers. 

Fig. 9 Two operating configurations for hollow fiber membranes (A) submerged (or immersed) and (B) sidestream (or cross-flow)...

According to configuration definition, three groups of hquid membranes are usually considered (see Fig. 1.1) bulk (BLM), supported or immobilized (SLM or ILM), and emulsion (ELM) liquid membrane transport. Some authors add to these definitions polymeric inclusion membranes, gel membranes, dual module hollow-fiber membranes, but, to my opinion, the first two types are the modifications of the SLM and the third is the modification of BLM. It will be discussed in detail in the respective chapters. 

The pressure difference over the membrane exists due to pumping of the aqueous phases through the feed and/or strip channels and has a special importance in hollow-fiber SLM configurations. When the pressure difference exceeds a certain critical value, the membrane phase is pushed out of the pores of the support. 

Membrane separation devices are assembled in a number of forms. In a flat sheet form the membrane is laid over a flat porous support. A unit would include a large number of the flat sheets separated by spacers and stacked together. In another configuration the fiat sheet may be spiral-wound with spacers around a perforated tube. Other arrangements involve tubular membranes or hollow fiber membranes assembled in bundles. In the tubular module the membrane is wrapped around a tubular... 

Based on the different modules used in technical scale membrane separation processes, there are four basic membrane configurations produced today on a large scale. These are flat sheet, tubular, capillary, and hollow fiber membranes. 

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