Prefilter cartridges

To extend its life, a microfiltration cartridge may contain two or more membrane filters in series, or as shown in Figure 7.13, a coarse prefilter cartridge... 

Table 11.11. Filtering a red wine on prefilter cartridge and membrane (Serrano, unpublished data)...

When all the preceding operations are efficiently carried out, simultaneous filtration with prefilter cartridges and membranes gives good results in terms of clarification quality (Table 11.11). Quality remains high for several days with satisfactory flow rates. It has, however, been observed that this technique, combined with the necessary preliminary clarification processes, may have a greater effect on the polysaccharide concentration than flat-sheet filtration (Section 11.10.2). It shonld therefore be used very carefully. Proper operating conditions are essential and filtration resnlts shonld be carefnlly monitored. 

Before introducing the feed into the RO system, the membrane was cleaned and wetted with deionized water. Initially feed water was passed through the micron prefilter cartridge using low-pressure pump to remove coarse solids. 

With an added white prefilter these cartridges can also be used in the presence of dusts and mists with a time-weighted average (TLV-TWA) of not less than 2 million particles per cubic foot. 

Air handling unit has been provided with prefilters two inches thick at a minimum and medium efficiency cartridge or bag filters. 

Regarding water filtration procedures first, prefilters should be provided to prevent large particulates from entering the system and microfiltration to remove bacteria. Prefilters are usually the replaceable cartridge type with porosities ranging as high as 25 pm. Microfiltration follows and is generally accomplished with 0.2-pm absolute filters, which will remove most bacteria. 

Figure 7.10 Sterile filtration of a small-volume pharmaceutical solution with a 142 mm plate-and-frame filter used as a prefilter in front of a small disposable cartridge final filter. From Gelman Science...

Figure 7.13 Typical in-line filtration operation using two cartridge filters in series. The prefilter removes all of the large particles and some of the smaller ones. The final polishing filter removes the remaining small particles...

Check cartridge filters The cartridge prefilters should be checked biweekly for pressure drop across them and to be sure they are seated properly. High pressure drop means it is time to replace the filters. Improper seating of the filters will lead to particulates bypassing the filters and fouling or abrasion (and destruction) of the membranes. 

Aerobic fermentation processes also require a continuous supply of large quantities of air, typically on the order of one volume of air per volume of liquid per minute, VVM. Sterilization of this air is mandatory in almost all fermentations. Absolute filter cartridges of polymeric membranes are now used almost exclusively in the fermentation industry. Relatively small units have replaced the large depth filters used in the past. Still, water and particulates pose a major problem for filters thus requiring the use of prefilters and traps to remove these contaminants before they reach the absolute filter. Parallel installation of the filters prevents a total shutdown of the fermentation process in the event of filter clogging. 

Dust/mist filtering respirator Dust/mist respirator, or respirator with dust/mist filtering cartridge, respirator with organic vapor-removing cartridge and pesticide prefilter, respirator with canister approved for pesticides, or air-sup-plying respirator... 

Dust/mist masks, prefilters, canisters, filtering and vapor-removing cartridges, and a few cartridge respirators are disposables. They cannot be cleaned, and they should be replaced often. 

Replace caps, if available, over cartridges, canisters, and prefilters. 

Seal the entire respirator in a sturdy, airtight container, such as a zip-closable plastic bag. If you do not seal the respirator immediately after each use, the disposable parts will have to be replaced more often. Cartridges, canisters, prefilters, and filters will continue to collect impurities as long as they are exposed to the air. 

The continuous enzyme membrane reactor (CMR). (1) Temperature-controlled water-bath (2) Feed tanig (3) Stirrer motor for feed tank (4) Feed pump (5) Feed inlet line to the reaction vessel (6) Reaction vessel (7) Magnetic stirring table (8) Prefilter (9) Recycle pum (10) Flowmeter (11) Membrane inlet pressure gauge (12) Hollow fiber membrane cartridge (13) Membrane outlet pressure gaug (1 Pressure adjusbneut valve (15) Retentate recycle line (16) Air bath environment (17) Pemieate (product) line (18) Permeate collection vessel (19) Electronic balance... 

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