Membrane plugging

This is considered a questionable failure because the pressure was increased to 40 psi after the membrane plugged at 30 psi. 

In order to estimate the ethanol/water composition as a function of x, a novel method (described in the Experimental section) was utilized, employing a membrane "plug" of assembled filter membranes. The steady-state ethanol concentrations determined for the experiment in which pure ethanol was in the donor chamber and saline in the receiver are presented in Figure 4. Further studies are needed to validate these results. Errors due to evaporation losses are believed to be of the order of 10%. 

Figure 4. Experimental ethanol/water concentration-distance profile across nitrocellulose acetate membrane plug.

Further study of the very first step of the layer formation process might lead to improved properties of the layer-support interface or to membrane "plugs" formed in the pore entrance instead of to films on top of the support. 

The experimental procedure used by the author places various prefilters on top of the selected membrane in 47 mm holders which are run in parallel on the process stream to be filtered. Usually, the test is carried out at constant flow rate and the rise in pressure drop is recorded versus the volume processed until the membrane plugs. The combinations providing the highest throughput are then evaluated with respect to cost of the media. 

The optimum match between prefilter and membrane will usually show both prefilter and membrane plugged so that neither one has carried the complete load by itself (see Figure 2.30). 

Hollow-fiber microporous silica membrane Plug-flow reactor 55% increase in cyclohexane conversion (the conversion in the membrane reactor approaches 100% whereas it is 45% in the conventional one) Koutsonikolas, Kaldis, ZaspaUs, and SakeUaropoulos (2012)... 

This problem seems to be overcome by the tangential flow filtration system, specifically developed for a large sample size (1-2 m ) by Broman and coworkers in order to collect water from Baltic Sea, where the suspended particulate generally occurs at concentrations of 0.2-0.3 mg/L [10]. The system is made of a microporous poly(vinylidene difluoride) membrane, where the filtrate is separated from the retentate with a constant cutoff of 0.45 xm. A tangential flow of water sweeps the surface of the membrane so that the particles are kept in suspension avoiding membrane plugging. The retentate (liquid) each of volume 3-5 L is collected and centrifuged the supernatant and pellet are thereafter extracted and analyzed. 

Reactive Waste Characteristics. To avoid membrane plugging and to ensure a long maintenance-free life, it is important to remove suspended solids and oils with conventional pretreatment. 

Raw seawater is taken from the Red Sea and then disinfected by sodium hypochlorite produced by a chlorine generation plant using filtered seawater as feed. Then ferric chloride as coagulant is added to the seawater feed ahead of dual-media filter (DMF) to help in reducing SDI values to suit the recommended SDI required by the membrane manufacmrer. The filtered feed water is then collected in a clear well, and particles greater than 10 p,m will not pass a cartridge filter in order to avoid membrane plugging. Sulfuric acid is added to the feed water to adjust pH to about 6.5. Sodium bisulfite (SBS) is injected for 7 h every... 

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