Centrifuges suspended batch

Figure 11.13 shows schematic diagrams of various types of filtering centrifuges. In Figure 11.13(a) a top suspended batch centrifuge is shown but there are also models that are not suspended but have the drive mechanism beneath the centrifuge. 

The main types of filtering centrifuges are suspended batch machines, which are discontinuous in their operation automatic short-cycle batch machines and continuous conveyor centrifuges. In suspended centrufuges the filter media are canvas or other fabric or woven metal cloth. In automatic machines fine metal screens are used in conveyor centrifuges the filter medium is usually the slotted wall of the basket itself. 

Pdndpal types of filteriiig centrifoges are suspended batch machines, automatic short-cycle batch machines and continuous cmiveyor centrifuges. In suspended centrifoges, the filter medium is usually canvas or a similar fabric, or woven metal cloth. Automatic machines employ fine metal screens. The filter medium in conveyor centrifoges is usually (he slotted wall of the bowl itself. 

Four batches of urokinase, obtained in this manner from 202 liters of urine, is pooled, amounting to 23.5 grams. The combined urokinase is suspended in 750 ml of 0.1 M phosphate-saline buffer at pH 6.2, stirred to dissolve the urokinase and centrifuged to remove the Celite. The residue is extracted two more times with 500 ml portions of 0.1 M phosphate-saline buffer. The combined extracts are filtered and labelled Extract 1. The residue is extracted three more times with 600 ml portions of buffer, the combined extracts are filtered and labelled Extract 2. 

In a typical batch suspension process (Figure 12-5), styrene is suspended in water by agitation and use of a stabilizer. The polymer forms beads. The bead/water slurry is separated by centrifugation, dried, and blended with additives. 

Another alcohol precipitation (at 50% alcohol concentration) is carried out as above, and the precipitate is dissolved in a small volume of il//30 phosphate buffer, pH 6.8, to obtain a concentrated solution (>1 mg./ml.) before carrying out the next step. l"he solutions obtained from several batches (the authors collected from 3 batches total vol., 39.3 ml. specific activity, 200 yield, 81%) are collected, and ammonium sulfate solution (saturated at 0°) is added to a saturation of s = 0.15 (6.96 ml. were abided). The temperature is then lowered to -15 to —20°, and precooled alcohol (—15°) is dropped in, to give a concentration of 50%. The suspension is allowed to stand for 4 hours at —15° and is then centrifuged. The precipitate is suspended in 15 ml. of Af/30 phosphate buffer, pH 6.8, and centrifuged, affording a clear solution (specific activity, 1520 yield, 98%). The last step is repeated once (yield, 64%). The final solution has a specific activity of 17,000 units per mg. of protein. 

About 40 kg of fly ash was collected from an average municipal waste incinerator. Three samples, taken randomly from the bulk material, were analysed, using validated laboratory procedures, in order to ensure that the levels of the twelve target congeners were adequate for certification (i.e. at least three times the limits of detection of MS). The collected material fulfilled these requirements it was treated in separate batches of 330 g which were transferred into 2 L erlenmeyer flasks and suspended in a mixture of 1 L bidistilled water and 100 mL of 12.5 mol L hydrochloric acid. The suspension was stirred magnetically for 2 h. The bulk of the fly ash was separated from the supernatant after centrifugation. The precipitate was then re-suspended several times... 

Another type of batch centrifuge is driven from the bottom, with the drive motor, basket, and casing all suspended from vertical legs mounted on a base... 

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