Primary filtration

Wlien solid soda ash is used to supply all the carbonate v alues in the precipitation step (eq. 9), a ca 10% Na2S solution results from the primary filtration step wliich can be concentrated to 40% Na2S in a three-effect evaporator train. Final concentration to 60%Na2S occurs in a high v acuurn single-effect evaporator. Hiis concentrated solution can then be fed to a Baker to produce a 60% sodium sulfide flake wliich is sold as co-product. 

In some breweries it is of extreme importance that the beer be absolutely sterile, and therefore it is necessary to use a sheet filter filtration in addition to the primary filtration. 

Fig. 1. ASPEN-Plus PFD of carbonic acid pretreatment process as analyzed in this study. Bl, pretreatment reactor (Rstoic) B2, screw mixer B3, blowdown tank and screw conveyor B4, slurrying tank and tank agitator B5, cooler B6, reflux drum and condenser B7, feed pump B8, in-line C02 mixer B9, heater BIO, pneumapress filter Bll, heat exchanger B12, loading pump B13, C02 compressor B14, primary filtrate pump.

The slurry or extraction mixture is filtered while hot, and the resulting filter cake is washed with about five to ten gallons of hot water the primary filtrate and wash water are combined and held for further processing. In order to insure complete extraction of the desired material, the filter cake is again extracted with about 100 gallons of water at 70°C. Although not essential, it... 

The acetic acid appears to aid in obtaining a complete and thorough extraction. After extraction for about three hours with agitation at a temperature of about 70°C, the slurry is again filtered and the cake washed as before with about five to ten gallons of hot water. The resulting filtrate and wash are then combined with the primary filtrate and wash. 

Mechanistically, most small solutes - glucose, salts, amino acids - are taken up again by specific active transporters. Active secretion likewise works by way of active transport. Typically, one transporter will pick up the substrate in question from the interstitial space and move it to the cytosol, from where a second transporter located in the apical membrane expels it into the nascent urine (see Figure 2.19). Water is recovered by the ensuing osmotic effect. Some solutes are partially or totally excluded from reuptake. Note that the final urine volume is about 100 times smaller than the primary filtrate. This means that the bulk of the fluid, salt and metabolites are actually reabsorbed. Some dmgs are subject to reuptake to a similar extent, too. 

Clean and aseptic processing areas should not be used for microbiological laboratory test procedures other than the primary filtration stage in the test for sterility. 

I. Primary Filtration. Classically, sand has been used as the medium in bed filters. While it is acceptable in most diaphragm and mercury brine processes, the possibility of dissolving small quantities of silica usually disqualifies sand from use in membrane plants. Other media such as garnet and anthracite are used instead. These have little effect on filter design, and plant conversions usually continue with the same vessels on line but the new fill substituted for sand, lypical particle sizes for both sand and anthracite are about 1 mm, but sand is, on the average, a bit smaller and contains more fines. Regardless of the fill, the apparatus still is frequently referred to as a sand filter. 

It is not only the polymer circulating in the blood and lymph which can participate in the formation of the intracellular depo. The epithelial cells of kidney tubules are a very important part of the intracellular compartment (Fig. 5 b). The primary filtrate formed during ultrafiltration through the capillary wall of the, glomerulus is further processed in the tubulus (tube-like structures with walls consisting of a monolayer of epithelial cells) at the end of which the concentrated urine is collected. In the tubulus, mainly in the part proximal to the glomerulus, more than 99 % of the fluid filtered in... 

As cake formation with the centrifugal pump only fills half the available volume in each chamber, the filtration takes place in two stages denoted as primary and secondary. Primary filtration takes place in accordance with the pump curve while secondary filtration proceeds via the flexible diaphragm at a constant pressure of 600 kPa. 

The primary filtration phase commences at a point on the pump curve where equation (6.18) is satisfied such that... 

Table 6.5 Data sequences for the primary filtration phase of a diaphragm press cycle. ...

The moisture content is calculated hy equation (6.16). The end of the primary filtration phase, represented hy the final row of values in Table 6.5, is determined from the specification that cake formation with the pump stops when the cake thickness on each filtration surface reaches 20 mm. Although the value is calculated hy equation (6.92), in reality, a point on the pump... 

From equation (6.24), which accounts for the presence of cake formed during the primary filtration stage, the total cycle time is... 

Prior to spinning it is necessary to filter various impurities out of the solution. Most of the impurities are introduced with the pulp feedstock, the principle ones being undissolved pulp fibres or inorganic compounds such as sand and ash. The solution is passed through two stages of filtration. The primary filtration is centrally located and consists of sets of sintered stainless steel media candle filter elements. The secondary stage filtration is achieved by candle filter elements associated with each spinning machine position. 

It is noticed that for such a filter containing fibres of the same size, it is unavoidable to have the minimum filter efficiency in filtering particles of certain sizes, as shown in Fig. 10.2. For very small particles less than dpi in diameter, the primary filtration mechanism is diffusion. For particles between dpi and dp2, the filter is less efficient, as the particles are too large for a great diffusion effect and too small for a large interception effect. For particles of diameter above dp2, the filter is very efficient again because the interception, along with inertial impaction, effects is predominant in the filtration. 

Additionally, if the brine circulating system of an existing mercury cell plant also serves membrane cells, all mercury must be removed in a chemical treatment facility. The brine from the primary filtration is acidified with hydrochloric acid to pH 2.0-2.5 and sodium sulfide is added to precipitate mercury sulfide. Subsequently, the brine is... 

The cartridges consisting of a single piece of filter medium are made from a perforated cylindrical core, of metal or stiff plastic, onto which the material of the filter medium is placed or formed. There are two basic types of integral media cartridges, depending upon which primary filtration mechanism is operating thin media, which work by surface filtration, followed if necessary by cake filtration on top of the surface layer and thick media, which work by depth filtration. 

Gelatine liquor usually involves a multi-stage filtration process. Primary filtration removes coarse particles of suspended matter, and secondary filtration further improves the clarity and imparts a brilliance to the liquor. Where the gelatine liquors are to be passed through ion exchange columns, coarse filtration takes place before the deionization stage. The primary operation is best accomplished with kieselguhr as the... 

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