Pleated cartridge

Stacked plate units were the first successful configuration for large scale MF, in spite of three distinct problems  

2 Tii-Clover Clamps Upstream Vent, Bubble Test 

Hollow Rod Connection Point X NPT (or Bubble Testing iDownstream) 

Elbow Gasket Elbow Bolts Washers Outlet Elbow Outlet, 2 Tri-Clover 2 Tri-Clover Gasket 

In the last decade, some manufacturers have been able to produce bubble-pointable (45-50 psi) pleated cartridges. These include tortuous-pore nylon and polyvinylidene fluoride membranes. The 0.2 ju cartridges show quantitative retention of Pseudomonas diminuta at challenge levels of 1010 to 1013 organisms. 

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HEiPA Throw-avvin pleated cartridge 0.02 J.3 +9 1 A- +99.9 99,9 25-50 0.4-0.8 Idigliest efficiency, used It) the cuidcnt inJuscrv pv - iilto i- dusts-... 

FIG. 20-49 NFF pleated cartridges and capsules. (Courtesy MiUtpore Corporation, Pall Corporation.)... 

Large-Area Configurations NFF membrane systems consist primarily of large, multiround housings that contain pleated cartridges inserted into a common base plate. These cartridges share a common feed and collect a common filtrate. 

Figure 6.24 Photographic representation of a range of filter types and their stainless steel housing. Most filters used on an industrial scale are of a pleated cartridge design, which facilitates housing of maximum filter area within a compact space (a). These are generally housed in stainless steel housing units (b). Some process operations, however, still make use of flat (disc) filters, which are housed in a tripod-based stainless steel housing (c). All photographs courtesy of Pall Life Sciences, Ireland...

Figure 7.11 Cut-away view of a simple pleated cartridge filter. By folding the membrane a large surface area can be contacted with the feed solution producing a high particle loading capacity. (From Membrana product literature)...

Despite the limited volumes that can be treated before a filter must be replaced, microfiltration is economical because the cost of disposable cartridges is low. Currently, a lO-in.-long pleated cartridge costs between US 10 and US 20 and contains 0.3-0.5 m2 of active membrane area. The low cost reflects the large numbers that are produced. 

FIGURE 5 Membrane module design, (a) Spiral-wound (Koch Membrane Systems) (b) hollow-fiber (Du Pont) (c) tubular (generic) (d) plate-and-frame (c) pleated cartridge (Millipore). [Figure 2(d) from Strathmann and Chmiel (1985)]. 

Vims filtration membranes are made of various polymers such as hydrophilized PVDF, hydrophilized PES, and cellulose. They are available in pleated cartridge and hollow-fiber formats. At present almost all vims filtration applications are performed in the direct filtration mode. 

Figure 17. Plugging test results a, pilot microscreen effluents b, filtrates from polishing by crossflow filtration through Ll-pm Acropor filter in axial filter (1.5 psi, 1000 rpm) and in pleated cartridge (loop).

Most pleated cartridges are sealed inside housings with "o-ring ". There are external and internal "o-rings" designs, both of which are vastly superior to the old gasket seals which can easily unseat under pressure. 

Some pleated cartridges are encapsulated in a disposable plastic housing so that, apart from external hose connections, there are no seals to worry about. 

Pleated cartridges are considerably more expensive than the equivalent membrane area in 293 mm discs (2 to 4 times as much). Some users insist that the lower replacement labor does not off-set the additional expense. However, the trend is definitely towards pleated cartridges for through-flow filtration. The movement to pleated cartridges has been accelerated with the discovery that some exhausted cartridges can be reused after backwashing. 

Figure 2.50 Modified pleated cartridge and housing for cross-flow filtration (CFF).

Figure 2.51 Increase in through-put for cross-flow filtration of 0.5% yeast with modified 0.2 micron capillary-pore membrane pleated cartridge.

More recently, a line of cross-flow pleated cartridges has been introduced with a controlled spacing for the cross-flow path between the pleats (see Figure 2.53).24 This alleviates the most serious problem with the simple modifications described in the preceding paragraph where bunching of pleats creates a non-uniform distribution of cross-flow channels. 

Figure 2.53 Improved cross-flow pleated cartridge with controlled flow-channel spacing (AcrofluxTM).

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