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Filter flocculation

Pressure belt filters, flocculants for, 77 639 Pressure cells, 73 430 Pressure cycle, change related to, 73 402 Pressure cycle data, 73 410-411 Pressure-dependent regioselectivity, 73 439-440... [Pg.757]

In the case of fixed bed (deep bed granular filters) flocculators the power is dissipated as laminar flow through granular media, with local velocity gradients in the pores formed by quasi-parabolic velocity distributions. The system is analogous to small-bore tubes (section 4.9.2) bearing in mind the capillary model concept of the Kozeny-Carman equation 4.68 for head loss through a fixed bed,... [Pg.153]

After 1-2 minutes, a flocculent precipitate of the phenylhydra2one, RCH. NNHCjHj, is produced. Filter and recrystallise from ethanol and take the m.p. (M.ps., p. 539 540.)... [Pg.342]

In a 500 ml. wide-mouthed reagent bottle place a cold solution of 25 g. of sodium hydroxide in 250 ml. of water and 200 ml. of alcohol (1) equip the bottle with a mechanical stirrer and surround it with a bath of water. Maintain the temperature of the solution at 20-25°, stir vigorously and add one-half of a previously prepared mixture of 26-5 g. (25 -5 ml.) of purebenzaldehyde (Section IV,115) and 7 -3 g. (9-3 ml.) of A.R. acetone. A flocculent precipitate forms in 2-3 minutes. After 15 minutes add the remainder of the benzaldehyde - acetone mixture. Continue the stirring for a further 30 minutes. Filter at the pump and wash with cold water to eliminate the alkali as completely as possible. Dry the solid at room temperature upon filter paper to constant weight 27 g. of crude dibenzalacetone, m.p. 105-107°, are obtained. Recrystallise from hot ethyl acetate (2-5 ml. per gram) or from hot rectified spirit. The recovery of pure dibenzalacetone, m.p. 112°, is about 80 per cent. [Pg.717]

The trend in the use of deep bed filters in water treatment is to eliminate conventional flocculators and sedimentation tanks, and to employ the filter as a flocculation reactor for direct filtration of low turbidity waters. The constraints of batch operation can be removed by using one of the available continuous filters which provide continuous backwashing of a portion of the medium. Such systems include moving bed filters, radial flow filters, or traveling backwash filters. Further development of continuous deep bed filters is likely. Besides clarification of Hquids, which is the most frequent use, deep bed filters can also be used to concentrate soflds into a much smaller volume of backwash, or even to wash the soflds by using a different Hquid for the backwash. Deep bed filtration has a much more limited use in the chemical industry than cake filtration (see Water, Industrial water treatment Water, Municipal WATERTREATiffiNT Water Water, pollution and Water, reuse). [Pg.388]

Pressure filters can treat feeds with concentrations up to and in excess of 10% sohds by weight and having large proportions of difficult-to-handle fine particles. Typically, slurries in which the sohd particles contain 10% greater than 10 ]lni may require pressure filtration, but increasing the proportion greater than 10 ]lni may make vacuum filtration possible. The range of typical filtration velocities in pressure filters is from 0.025 to 5 m/h and dry sohds rates from 25 to 250 kg nY/h. The use of pressure filters may also in some cases, such as in filtration of coal flotation concentrates, eliminate the need for flocculation. [Pg.393]

Originally designed for the continuous filtration of conditioned sewage sludges, as were most of the filter belt presses available, the Manor Tower press is increa singly used for the treatment of paper mill sludge, coal, or flocculated clay slurries. [Pg.408]

Fig. 5. Effect of polymer dosage on different observed properties of flocculated slurry (40). Comparison of five parameters in a flocculation system (8%fluorite suspension + polyacrylamide Cyanamer P250). A, Rate of settling of floe boundary, in cm/s B, height of settled bed, cm C, height of consoHdated filter-cake, cm D, refiltration rate, arbitrary units and E, clarification, % optical transmission of 1 cm of supernatant Hquid after 3 min settling... Fig. 5. Effect of polymer dosage on different observed properties of flocculated slurry (40). Comparison of five parameters in a flocculation system (8%fluorite suspension + polyacrylamide Cyanamer P250). A, Rate of settling of floe boundary, in cm/s B, height of settled bed, cm C, height of consoHdated filter-cake, cm D, refiltration rate, arbitrary units and E, clarification, % optical transmission of 1 cm of supernatant Hquid after 3 min settling...
Eor vacuum filters, both the rate of filtration and the dryness of the cake may be important. The filter cake can be modeled as a porous soHd, and the best flocculants are the ones that can keep the pores open. The large, low density floes produced by high molecular weight polymers often coUapse and cause blinding of the filter. Low molecular weight synthetic polymers and natural products that give small but rigid floes are often found to be the best. [Pg.35]

Eor evaluation of flocculants for pressure belt filters, both laboratory-scale filters and filter simulators are available (52,53) in many cases from the manufacturers of the full-scale equipment. The former can be mn either batchwise or continuously the simulators require less substrate and are mn batchwise. The observed parameters include cake moisture, free drainage, release of the cake from the filter cloth, filter blinding, and retention of the flocculated material during appHcation of pressure. [Pg.36]

Addition Point. The flocculant addition point in a continuous system can also have a significant effect on flocculant performance. The turbulence as the flocculant is mixed in and the floes travel toward the point where they enter the thickener or filter causes both the formation and breakup of floes. Usually there is an optimal addition point or points which have to be determined empirically. In cases where the same polymer is being added at two or more points, the relative amounts added at each point may also affect performance. Thus providing multiple addition points in the design of new installations is recommended (56). [Pg.36]

The softened seawater is fed with dry or slaked lime (dolime) to a reactor. After precipitation in the reactor, a flocculating agent is added and the slurry is pumped to a thickener where the precipitate settles. The spent seawater overflows the thickener and is returned to the sea. A portion of the thickener underflow is recirculated to the reactor to seed crystal growth and improve settling and filtering characteristics of the precipitate. The remainder of the thickener underflow is pumped to a countercurrent washing system. In this system the slurry is washed with freshwater to remove the soluble salts. The washed slurry is vacuum-filtered to produce a filter cake that contains about 50% Mg(OH)2. Typical dimensions for equipment used in the seawater process may be found in the Hterature (75). [Pg.348]

The remaining tailings left over from the clay fractionation step is either flocculated with alum, high molecular weight polymers, or a weak (pH 3.0) solution of sulfuric acid, and stored in settling ponds as waste, or may be filtered and sold to the brick industry as a coating material. It also may be dried and sold as a filler in plastics and textured paint (qv). [Pg.288]

Flocculants and surfactants (qv) are used frequently as filter aids, particularly when slimes are present or when the particles to be filtered are very fine and difficult to filter. Low molecular weight polymers are more commonly used. These form small, dense floes which provide higher cake porosity. [Pg.415]

Overflow from the first clarifier, typically a 20% BaS solution, is filtered and sent on to the precipitation department. Settling of soflds in the clarifiers can be enhanced by various flocculating agents (qv), preferably weakly anionic polyacrylamides (17). [Pg.478]

Fig. 6. Effect of acrylate content on coal refuse filter-cake moisture (59) (—), the effect on a longer chain flocculant (mol wt of 8 )... Fig. 6. Effect of acrylate content on coal refuse filter-cake moisture (59) (—), the effect on a longer chain flocculant (mol wt of 8 )...

See other pages where Filter flocculation is mentioned: [Pg.807]    [Pg.984]    [Pg.143]    [Pg.387]    [Pg.389]    [Pg.389]    [Pg.397]    [Pg.403]    [Pg.408]    [Pg.35]    [Pg.36]    [Pg.443]    [Pg.573]    [Pg.315]    [Pg.347]    [Pg.354]    [Pg.413]    [Pg.414]    [Pg.134]    [Pg.490]    [Pg.121]    [Pg.17]    [Pg.126]    [Pg.275]    [Pg.293]    [Pg.18]    [Pg.539]    [Pg.231]    [Pg.18]    [Pg.22]    [Pg.22]    [Pg.22]    [Pg.22]    [Pg.23]    [Pg.23]   


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