Filtration parameters

Materials suitable as filter aids include diatomaceous earth, expanded perilitic rock, asbestos, ceUulose, nonactivated carbon, ashes, ground chalk, or mixtures of those materials. The amount of body feed is subject to optimisa tion, and the criterion for the optimisa tion depends on the purpose of the filtration. Maximum yield of filtrate per unit mass of filter aid is probably most common but longest cycle, fastest flow, or maximum utilisation of cake space are other criteria that requite a different rate of body feed addition. The tests to be carried out for such optimisation normally use laboratory or pilot-scale filters, and must include variation of the filtration parameters such as pressure or cake thickness in the optimisation. 

For cakes of high permeabihty, the capillary drain height may be an insignificant fraction of cake thickness, and film drainage becomes the controlling factor in a centrifugal field (7). Under unsteady-state conditions, equation 18 represents the drainable Liquid left in the cake as a function of the centrifugal filtration parameters ... 

TABLE 13.6 Filtration Parameters in Metric and British Units... 

Filtration parameter Metric Units British Equivalency... 

Changes to filtration parameters for aseptic processing (including flow rate, pressure, time, or volume, but not filter materials or pore size rating) that require additional validation studies for the new parameters. 

Example 7.9 A CaCOs sludge with cake filtration parameters determined in the previous example is to be dewatered in a vacuum filter under a vacuum of 630 mmHg. The mass of filtered solids per unit volume of filtrate is to be 60 kg/m The filtration temperature is determined to be 25°C and the cycle time, half of which is form time, is five minutes. Calculate the filter yield. 

Values of Filtration Parameters for Various Solid-Nitrogen Systems... 

The area of the filter leaf was 500 cm. Data were taken of the volume of the filtrate (L) against time (sec) at pressures of 0.5 and 0.8 bar. The results will be analyzed for the filtration parameters ... 

Although both the above procedures provide useful comparative data, such information should only be used as a guide for media selection and not as a means of specifying filtration parameters or indeed the actual filtration performance. Thermal and chemical conditions and the condition of the cages inside the filter, none of which can be simply reproduced in the laboratory, may well eclipse the laboratory predictions. 

Nanofiltration membranes based on poly(ether ether ketone) modified with a mixture of ammonia with Ar or hydrogen show much better dye filtration parameters than the unmodified or commercial membranes (Buonomenna et al. 2009). 

Phase 1 tab (always filtration) Parameters specific to the filtration phase including two scale-up coefficients for specific cake resistance, two scale-up coefficients for cake solids concentration and, where appropriate, filtration pressure or vacuum. 

Table VII. 8. Filtration Parameters (AI2O3 content 9 mg/liter)...

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