Settling characteristics

FIG. 18 82 Combined effect of particle coherence and solids concentration on the settling characteristics of a suspension. 

FIG. 18-135 Coding the settling characteristics of a slurry. (Purchas, Solid/Liqnid Separation Equipment Scale-Up, Uplands Press, Croydon, England, 1977, p. 11, hy permission.)... 

Slurry-settling characteristics Slurry-filtering characteristics... 

Starting point for evaluating the settling characteristics of suspended solids for dilute systems. Note that from the definition of the Reynolds number, we can readily determine the settling velocity of the particles from the application of the above expressions (u, = /xRe/dpp). The following is an interpolation formula that can be applied over all three settling regimes ... 

Although it has been known that zinc can be precipitated from acid wastestreams by the use of lime, the resultant sludge has been of low zinc assay, contaminated with other compounds, and with very poor settling characteristics. In commercial operations, the sludge presented a disposal problem and recovery of zinc suitable for recycle was impossible. 

Wastewater characteristics must be known in order to select a suitable treatment system. For this purpose, the wastewater samples taken from the sources were analyzed to determine various parameters. Also, the quantities of chemicals (NaOH) required for neutralization and settling characteristics were determined. These were made separately for continuous and batch discharges. Since the system is to be designed according to the continuous discharge of wastewaters from the batch system to the treatment plant, mixed wastewater was prepared in quantities proportional to the flow rates. The quantity of NaOH required for lOOOmL of mixed wastewater is shown in Table 28.2.13... 

To determine the settling characteristics of a sediment, you drop a sample of the material into a column of water. You measure the time it takes for the solids to fall a distance of 2 ft and find that it ranges from 1 to 20 s. If the solid SG = 2.5, what is the range of particle sizes in the sediment, in terms of the diameters of equivalent spheres ... 

The settling characteristics of hindered settling systems differ significantly from those of freely settling particles in several ways ... 

Continuous bench-scale operations to study the extraction of copper and other metals present in the leach liquor effects of variables such as temperature, 0/A ratio, solvent composition, extraction kinetics, settling characteristics, etc. 

The third point is especially important when the process runs at high temperature, but the choice of the diluent also affects the settling characteristics of the mixed phases. As it can be seen in Table VII, many different diluents may be considered. It should be realized that the commercial diluents are "cuts" obtained during the production of chemicals from petroleum "feedstocks" and as such are complex mixtures. 

For particles with f < 0.67, the correlations of Becker (Can. J. Chem. Eng., 37, 85—91 [1959]) should be used. Reference to this paper is also recommended for intermediate region flow. Settling characteristics of nonspherical particles are discussed by Clift, Grace, and Weber, Chaps. 4 and 6. 

Bosman, D.J. Kalos, J.M. "Relation between aeration rates and settling characteristics of activated sludge" Water Poll. Control, (S. Africa), 1978, 101-103. 

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