Pressure filtration comparison

The experiments consisted of three parts. In the first part, the characterization of minerals was explained by using x-ray diffractometer and electron microscope studies. Also, it was performed electrokinetic s studies of suspension. The effect of particle shape and size on the vacuum and pressure filtration of minerals has been investigated in the second part of the study. At the last part, the comparison of the particle shape and size effect on shear strength of the mineral filter cakes was performed. 

FIG, 18-185 Comparisons of frictional stress distributions in expression and pressure filtration. 

A laboratory pressure filter (Fig. 18-189) equipped with a piston can provide a simple feasibility test. In this kind of device, the suspension is poured into the filter cylinder, and the first stage of the test is just like a pressure filtration test. After the filtration, compressed air or water is used to push the piston down to squeeze the filter cake. The filtration rate, final cake thickness and dryness are recorded for evaluation and comparison with the same test without the compression by the piston. 

Table IV. Comparisons Using the Modified Cyclohexane Pressure Filtration for Slurries Reacted at Low Temperatures...

Nagesha et al. [71] evaluated the selectivity of membranes with dense silica and PI as the active layer and support, respectively, on the permeation of tocopherols. They used samples of deodorized distillate of soybean oil (DDOS), diluted or not in hexane and DDOS oil ester, without dilution. For comparison, model systems consisting of mixtures of oleic acid and tocopherols in different proportions (80 20 and 50 50), diluted or not in hexane, were selected. In a standard model, (free of hexane) was added to a mixture of fatty acids methyl esters (FAMEs) from soybean oil and tocopherols (90 10). Experiments were conducted on a pressurized filtration unit with nitrogen at 30 bar, 30 C, and 800 rpm. The study revealed that preferential permeation of tocopherols in relation to other constituents of low molecular weight (fatty acids and FAMEs) occurs. The selectivity of the membrane to tocopherols increased with the esterifled DDOS. 

The Flat-bed pressure filter (Hydromation Engineering Co. Ltd.) (19) is based on the above principle. The pressure compartment consists of two halves, top and bottom. The bottom half is stationary while the top half can be raised to allow the belt and the cake to pass out of the compartment, and can be lowered onto the belt during the filtration and dewatering stage. The filter can be considered as a horizontal filter press with an indexing cloth in comparison with a conventional filter press, however, this filter allows only the lower face of the chamber to be used for filtration. 

The CDC-NIH document describes, in detail, the different uses of the different classes and types of BSCs and the type of protection (personnel, product, and environmental) each type provides. The document also provides a detailed comparison of filtration (air cleaning), airflow pattern (into the cabinet from the room or from the supply duct), and necessary performance tests (leak, velocity profile, differential pressure, etc.) for each type of BSC (see also Simons ). 

Filtration. To separate the dissolved from the particulate fraction filtration or centrifugation will be necessary. This causes a severe risk of contamination it is therefore often not carried out with open ocean samples, where the concentrations of suspended material are low. The presence of phytoplankton or a variable concentration of suspended matter affects the total concentration and a comparison of samples can thus become difficult. In speciation Studies the presence of particles may influence the results even more (complexation, adsorption), therefore filtration over acid washed membrane or screen filters in an appropriate filtration apparatus is recommended for all natural samples (Bewers et al., 1985). High pressure during filtration should be avoided ruptured (plankton-) cells will contribute organic matter, nutrients and trace metals to the solution. A pressure < 25 kPa is recommended (Florence and Batley, 1980). 

Defiance, L. and Jaffrin, M.Y. (1999) Comparison between filtrations at fixed transmembrane pressure and fixed permeate flux application to a membrane bioreactor used for wastewater treatment. Journal of Membrane Science, 152, 203-210. 

Table 6 Comparison of Pressure Drop for Two Filters with Identical Total Filtration Area but Different Cell Configurations (in. Hg)...

Figure 8.19 shows the flux-time profiles obtained in filtration of 5% yeast cell suspension using a mbular membrane of 6 mm i.d. (inside diameter) and 0.14 pm pore size with a helical baffle (HB), a rod baffle (RB), and the mbular membrane without baffle (NB) [35]. The comparison has been made at the same hydraulic-dissipated power, which is defined as the product of the flow rate and the pressure drop along the mbular membrane, or the energy consumed to generate the crossflow through the mbular membrane. Using the hydraulic-dissipated power rather than the crossflow rate as a control parameter for the comparison of the mbular membrane with and without inserts eliminates the effect of the reduced crossflow section by... 

KaUioinen M, Pekkarinen M, Manttari M, Nystrbm M, and Nuortila-Jokinen J. Comparison of the performance of two different regenerated cellulose ultrafiltration membranes at high filtration pressure. J. Membr. Sci. 2007 294 93-102. 

Leuf Filter. In comparison to nutsche filters, leaf filters provide more filtration area in the same volume of pressure vessel. They are more suitable for handling... 

Incompressible cakes have flow rates that are dependent upon the pressure or driving force on the cake. In comparison, compressible cakes, i.e., where s approaches 1.0, exhibit filtration rates that are independent of pressure as shown below. 

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