Ultrafiltration module

The axial filter (Oak Ridge National Laboratory) (30) is remarkably similar to the dynamic filter in that both the rotating filter element and the outer shell are also cylindrical. An ultrafiltration module based on the same principle has also been described (31). Unlike the disk-type European dynamic filters described above, the cylindrical element models are not so suitable for scale-up because they utilize the space inside the pressure vessel poorly. 

Fig. 24. (a) Typical tubular ultrafiltration module design. In the past, modules in the form of 2—3 cm diameter tubes were common more recendy, 0.5—1.0... 

What should be the pressure aeross an ultrafiltration module, in order to achieve a permeate flux of 400 Liter/m -day. The clean membrane resistance is 2.4 X 10 1/m. 

Figure 4.2 Enzyme-hi-membrane-reactor synthesis of 1-pheny 1-2-propanol from l-phenyl-2-propanone applying a stirred-tank reactor, ultrafiltration module, extraction module and distillation...

Figure 19.3. Tubular and plate-and-frame membrane modules for reverse osmosis and ultrafiltration, (a) Construction and flow pattern of a single 1 in. dia tube with membrane coating on the inside in Table 19.4, the Ultracor model has seven tubes in a shell and the Supercor has 19 [Koch Membrane Systems (Abcor)]. (b) Assembly of a plate-and-frame ultrafiltration module (Danish Sugar Co.), (c) Flow in a plate-and-frame ultrafiltration module.

Figure 3.40 Typical tubular ultrafiltration module design. The membrane is usually cast on a porous fiberglass or paper support, which is then nested inside a plastic or steel support tube. In the past, each plastic housing contained a single 2- to 3-cm-diameter tube. More recently, several 0.5- to 1.0-cm-diameter tubes, nested inside single housings, have been introduced. (Courtesy of Koch Membrane Systems)...

Because of the challenging environment in which ultrafiltration membranes are operated and the regular cleaning cycles, membrane lifetime is significantly shorter than that of reverse osmosis membranes. Ultrafiltration module lifetimes are rarely more than 2-3 years, and modules may be replaced annually in cheese whey or electrocoat paint applications. In contrast, reverse osmosis membranes are normally not cleaned more than once or twice per year and can last 4-5 years. 

The need to control concentration polarization and membrane fouling dominates the design of ultrafiltration modules. The first commercially successful... 

Figure 13.18 Continuous recycle fermentor membrane reactor. An ultrafiltration module removes the liquid products of fermentation as a clean product. This system is being developed for production of ethanol, acetone and butanol by fermentation of food processing waste streams...

Since selectivity is a function of the local permeate flux, and thus the local transmembrane pressure, selectivity can be further improved by maintaining a nearly uniform and low transmembrane pressure throughout the ultrafiltration module. Following the early work from Sandblom, HPTFF technology uses, when required, a cocurrent permeate flow that is accomplished by the addition of a coflow loop and pump on the permeate side. 

Mobile units for photocatalytic treatment have been constructed (126,127). The European Joint Research Center laboratory pilot plant, placed on a truck, includes Ti02 loaded on membranes in UV-irradiated tubular reactors behind microfiltration and ultrafiltration modules. The waste water flow rate for this unit was typically 40 L hr-1, and hydrogen peroxide was added to the photocatalytic process (134). 

Continuous mns were carried out in a stirred cell ultrafiltration module using the fluoropolymer membrane FS61PP with a nominal molecular weight cut-off of 20kDa. The reactor, loaded with an appropriate amount of resting cells, was fed with a buffered substrate solution by a peristaltic pump with the flow rate set at... 

Hallstrom B and Lopez-Levia M, Description of a rotating ultrafiltration module. Desalination. 1978 24 273-279. 

In order to obtain a sufficiently large membrane area on an industrial scale, hollow fibre ultrafiltration modules are applied (similar types to those used for protein purification). Since the concentration of NAD(H) does not change in the steady state and there is no NAD(H) in the entrance or exit flow, it becomes clear that the actual concentration of pyruvate in the reactor is equal to the concentration in the feed. Since there is a non-zero concentration of pyruvate in the reactor (and in the exit flow), some pyruvate has to be added to the reactor continuously in order to keep the reaction going. The rate equations of both reactions are required to calculate the precise rate of pyruvate addition. 

Manno, P. Moulin, P. Rouch, J.C. Clifton, M. Aptel, P. Mass transfer improvement in helically wound hollow-fibre ultrafiltration modules bentonite and yeast suspensions. Sep. Purif Tech. 

Friedli, H. Fournier, E. Volk, T. Kistler P. "Studies on New Process Procedures in Plasma Fractionation on an Industrial Scale" Vox Sang. 1976, 31, pp 283-288. Hallstrom, B. Lopez-Leiva M. "Description of a Rotating Ultrafiltration Module" Desalination. 1978, 24, pp 273-279. 

Pleated ultrafiltration module. The axial filter is convenient for experiments, in that volumes small relative to ordinary ultrafiltration systems can be studied and in that pumping of viscous solutions is limited to that necessary to replace filtrate or concentrate bled from the chamber, rather than that necessary to maintain desired cross flow velocities. There is no obvious reason it could not be scaled up to moderate sizes for practical separations, but so far as we know, no large-volume axial filters are available. For the operations of interest, any of the commercial ultrafiltration systems would be candidates. We have tested one module, recently developed by Gelman, which incorporates a pleated membrane (Figure 5), with somewhat more open feed passages than those of spiral-wound membranes, and which allows backwashing. Other applications of the module were discussed at this symposium by A. Korin in a paper coauthored by G. B. Tanny, and a written account is presumably in these proceedings. 

Figure 5.18 Process scheme for combination of a hydrogenation reactor with an ultrafiltration module (1) reactant reservoir, (3) reactor, (5) ultrafiltration module, (6) product tank and (2), (4) are pumps as shown by symbols.

Figure 1. Enzyme Membrane Reactor (EMR) for bulk production - schematic representation. 1, ultrafiltration module 2, peristaltic pump 3, septum 4, sterile filter 5, metering pumps 6, reactor loop (ther-mostated) pHI, pH indication TIR, temperature indication and regulation PI, pressure indication.

As a new option, for the bioconversion of poorly soluble substrates the classical EMR-concept can be extended to an Emulsion Membrane Reactor , comprising a separate chamber for emulsification (with a hydrophilic ultrafiltration membrane), an EMR-Ioop with a normal ultrafiltration module, and a circulation pump. This approach has been successfully demonstrated for the enzymatic reduction of poorly soluble ketones [107]. Using this device, e.g., for the enantioselective reduction of 2-octanone to (S)-2-octanol (e.e. >99.5%) with a carbonyl reductase from Candida parapsilosis under NADH-regeneration with FDH/for-mate, the total turnover number was increased by a factor 9 as compared with the classical EMR. 

Cojocaru, C., Zakrzewska-Trznadel, G., Miskiewicz, A., Removal of cobalt ions from aqueous solutions by polymer assisted ultrafiltration using experimental design approach. Part 2 Optimization of hydrodynamic conditions for a cross-flow ultrafiltration module with rotating part, J. Hazard. Mater. 169, 610, 2009. 

Figure 5.16 shows the process scheme of the commercial acylase process. In a separation unit of several ultrafiltration modules in parallel, acylase is removed from the reactor outlet stream and recycled to the reactor. Subsequently,... 

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