Ultrafiltration configurations

Ghosh, R, Novel cascade ultrafiltration configuration for continuous, high-resolution protein-protein fractionation A simulation study, J. Membr. Sci., 226, 85, 2003. 

Consider the batch ultrafiltration configuration of Figure 7.2.5(d). We would like to determine the time required to go from an initial volume Vja of the solution to the final volume Vfe (feed concentration of the protein Cjf in the batch solution varies from the initial value to the final value Cy. 

In general there are three main types of hoUow-fiber flow configurations. In the most common, for reverse osmosis and ultrafiltration, the feed... 

Commercial industrial ultrafiltration equipment first became available in the late 1960s. Since that time, the industry has focused on five different configurations. 

The earhest reverse osmosis and ultrafiltration units were based on flat membrane sheets ia arrangements similar to that of a plate and frame filter press. Siace then, mote efficient membrane configurations, ie, tubular, spiral wound, and hoUow fiber, have emerged (96—98). 

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). 

Aim of this work was to optimise enzymatic depolymerization of pectins to valuable oligomers using commercial mixtures of pectolytic enzymes. Results of experiments in continuous and batch reactor configurations are presented which give some preliminary indications helpful to process optimisation. The use of continuous reactors equipped with ultrafiltration membranes, which assure removal of the reaction products, allows to identify possible operation policy for the improvement of the reaction yield. 

Cross-flow is the usual case where cake compressibility is a problem. Cross-flow microfiltration is much the same as cross-flow ultrafiltration in principle. In practice, the devices are often different. As with UF, spiral-wound membranes provide the most economical configuration for many large-scale installations. However, capillary devices and cassettes are widely employed, especially at smaller scale. A detailed description of cross-flow microfiltration had been given by Murkes and Carlsson [Crossflow Filtration, Wiley, New York (1988)]. 

Also included are sections on how to analyze mechanisms that affect flux feature models for prediction of micro- and ultrafiltration flux that help you minimize flux decline. Descriptions of cross-flow membrane filtration and common operating configurations clarify tf e influence of important operating parameters on system performance. Parameters irdlucnc irxj solute retention properties during ultrafiltration arc identified and discussed or treated in detail. 

Ultrafiltration hollow-fiber modules are usually made with a shell and tube configuration. The fibers are potted at both ends of the module with the fiber lumen open for recirculation of the process stream (Figure 21). Naturally, strainers or prefilters must be utilized to eliminate plugging of the fibers. At Nude-pore, it has been shown that larger diameter hollow fibers, 1.5 to 3mm in i.d., are much less prone to fouling. Fortunately, all UF hollow fiber systems can be back-washed and are amenable to a number of cleaning techniques. 

Just like chemical processes, biocatalytic reactions are performed most simply in batch reactors (Figure 5.5a). On a lab scale and in the case of inexpensive or rapidly deactivating biocatalysts, this is the optimal solution. If the biocatalyst is to be recycled, but the mode of repeated batches is to be maintained, a batch reactor with subsequent ultrafiltration is recommended (batch-UF reactor Figure 5.5b). The residence times of catalyst and reactants are identical in all batch reactor configurations. 

The simultaneous separation and recovery of acidic and basic bioactive peptides by employing electrodialysis with ultrafiltration membranes has also been investigated recently [30]. This work aims at demonstrate the feasibility of separating peptides from a beta-lactoglobulin hydrolysate, using an ultrafiltration membrane stacked in an electrodialysis cell, and a study of the effect of pH on the migration of basic/ cationic and acid/anionic peptides in the electrodialysis configuration. 

Table 16.3 Advantages and limitation of various module configurations for microfiltration and ultrafiltration membranes.

The difference between conventional dead-end filtration and cross-flow filtration is the configuration of the system. For large-scale operations, only cross-flow filtration will be used. The membranes for miocrofiltration as well as ultrafiltration are commonly utilized in a variety of filtration devices. There are three basic types of tangential flow filtration devices plate and frame, hollow fiber, and spiral wound membranes. 

Ceramic membranes are the most often used asymmetric membranes. When the separative layer, which is usually in contact with the feed, is also photoactive, irradiation must be applied on this top layer. A second configuration can also be considered. It consists of a conventional asymmetric membrane without photoactive separative layers but with a photoactive coating deposited on the surface of the grains of the support. In this case, the irradiation is apphed on the opposite side of the membrane, in contact with the permeate. Such a configuration could be used for instance in the final treafment of wastewater with a low-ultrafiltration membrane which provides retention of colloids and macromolecules, whereas small unretained molecules like VOCs would be photo-oxidized on the other side of the membrane (Figure 25.14). 

Figure 8.42 shows the basic configuration of electrofiltration, where an electric field is applied across micro or ultrafiltration membranes in flat sheet, tubular, and SWMs. The electrode is installed on either side of the membrane with the cathode on the permeate side and the anode on the feed side. Usually, the membrane support is made of stainless steel or the membrane itself is made of conductive materials to form the cathode. Titanium coated with a thin layer of a noble metal such as platinum could, according to Bowen [93], be one of the best anode materials. Wakeman and Tarleton [94] analyzed the particle trajectory in a combined fluid flow and electric field and suggested that a tubular configuration should be more effective in use of electric power than flat and multitubular module. 

Da Costa AR and Fane AG, Net-type spacers Effect of configuration on fluid flow path and ultrafiltration flux, Ind. Eng. Chem. Res. 1994 33 1845-1851. 

In this chapter, we will introduce fundamental concepts of the membrane and membrane-separation processes, such as membrane definition, membrane classification, membrane formation, module configuration, transport mechanism, system design, and cost evaluation. Four widely used membrane separation processes in water and wastewater treatment, namely, microfiltration (MF), ultrafiltration (UF), nanofiltrafion (NF), and reverse osmosis (RO), will be discussed in detail. The issue of membrane foufing together with its solutions will be addressed. Several examples will be given to illustrate the processes. 

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