Solid settled

Tlocciilant addition rate can be regulated in proportion to the thickener oliirnetric feed rate or solids mass How in a feed-fonvard mode, or in a feed-back mode on either rake torque, iindertlow density, settling solids (sludge) bed le el, or solids settling rate. Of these, feed-fonvard on mass How or feed-back on bed le el are probably the most common. In some feed-fonvard schemes, the ratio multiplier is trimmed by one of the other parameters. 

Plate-and-Frame Tests These tests should be conducted if the use of a filter press in the plant is anticipated at least a few confirming tests are advisable after preliminaiy leaf tests, unless the sluriy is veiy rapidly filtering. A laboratory-size filter press consisting of two plates and a single frame may be used. It will permit the observation of solids-settling, cake-pacldug, and washing behavior, which may be quite different for a frame than for a leaf. 

Filtration Cross-flow filtration (microfiltration includes cross-flow filtration as one mode of operation in Membrane Separation Processes which appears earlier in this section) relies on the retention of particles by a membrane. The driving force for separation is pressure across a semipermeable membrane, while a tangential flow of the feed stream parallel to the membrane surface inhibits solids settling on and within the membrane matrix (Datar and Rosen, loc. cit.). 

Dissolved Solids Boiling Pt/Freezing Point For Liquids/Solid Mixtures Bulk Density Total Solids Content Solids Size Distribution Suspended Solids Content Suspended Solids Settling Rate Dissolved Solids Content Free Water Content Oil and Grease Content Viscosity For Gases Density... 

In this diagram the key features are A - Diffusion baffle this serves four roles. First to dissipate the velocity head, thereby improving the overall hydraulic characteristics of the separator. Next, to direct incoming flow downward and outward maximizing the use of the separator volume. Third, to reduce flow turbulence and to distribute the flow evenly over the separator s cross-sectional area. Finally, to isolate inlet turbulence from the rest of the separator. B- Internal chambers In the sediment chamber, heavy solids settle out, and concentrated slugs of oil rise to the surface. As the oily water passes through the parallel corrugated... 

Clarifier Settling tank, sedimentation basin, A tank or basin in which wastewater is held for a period of time, during which the heavier solids settle to the bottom and the lighter material will float to the water surface. 

Septic Tank Untreated liquid household wastes (sewage) will quickly clog your absorption field if not properly treated. The septic tank is a holding tank in which this treatment can take place. When sewage enters the septic tank, the heavy solids settle to the bottom of the tank the lighter solids, fats and greases partially decompose and rise to the surface and form a layer of scum. The solids that have settled to the bottom are attacked by bacteria and form sludge. 

The effect of carryover and after-precipitation is that solids settle out and cause pre-boiler system fouling and result in reduced flow and equipment waterway blockages. Check valves are especially prone to blockage. 

On addition of the acetic acid, a small amount of black solid settles out, but this dissolves when the solution is swirled for several minutes. The potassium salt of ethyl o-nitrophenyl-pyruvate, although it undergoes no apparent change in color, does not keep indefinitely in the dry state. After 3 weeks of storage at room temperature, the salt still produced a yellow solution when dissolved in acetic acid, but, after 3 months of storage, the dry salt produced a deep-red solution from which an oil, rather than crystalline ester, was obtained after catalytic hydrogenation. 

Because the batch flux data are obtained in a closed system with no outflow, the net solids flux is zero in the batch system and Eq. (14-40) reduces to FL = —(pV%/ 1 — cp). Note that FL and Vs are of opposite sign, because the displaced liquid moves upward as the solids settle. The relative velocity between the solids and liquid is Vr = Vs — VL which, from Eq. (14-20), is Vr = Fs/(1 — relative velocity that controls the dynamics in the thickener. If the underflow draw-off rate from the thickener is gu, the additional solids flux in the thickener due to superimposition of this underflow is qu = Qu/A = Vu. Thus, the total solids flux at any point in the thickener (qs) is equal to the settling flux relative to the suspension (i.e., the batch flux qsb) at that point, plus the bulk flux due... 

The reaction flask is cooled in an ice bath and the contents stirred while the Grignard reagent is added over a period of 10 minutes. The ice bath is removed and stirring is continued for 4 hours. The reaction mixture is allowed to stand for about 12 to 16 hours, during which time an off-white solid settles, leaving a clear orange-colored solution. 

Percent solid settled In tests where adsorption and flocculation were determined simultaneously, the 200 ml sample was allowed to settle for 30 seconds and then 100 ml of the supernatant was removed using a suction device and after centrifugation analyzed for residual polymer concentration. The minimum level of detection was at 0.5 to 1 ppm and the reproducibility of the adsorption measurements was 2-3%. The settled 100 ml portion was analyzed for solid content. Flocculation due to polymer addition is measured by noting % solid settled as a function of polymer concentration. 

The flocculation responses studied are settling rate, percent solid settled, supernatant clarity, sediment volume and slurry viscosity. The polymer concentration and polymer anionicity required for maximum flocculation were seen clearly to depend on the response studied. Both the settling rate and the supernatant clarity with the nonionic polyacrylamide flocculent showed at pH 4.5 a marked increase to a maximum at about 25 mg/kg, whereas with the anionic polymer settling rate and supernatant clarity showed maxima at 10-25 mg/kg, but the system was totally... 

Seal legs are frequently used in conjunction with solids-flow-control valves to equalize pressures and to strip trapped or adsorbed gases from the solids. The operation of a seal leg is shown schematically in Fig. 17-20. The solids settle by gravity from the fluidized bed into the seal leg or standpipe. Seal and/or stripping gas is introduced near the bottom of the leg. This gas flows both upward and downward. Pressures indicated in the illustration have no absolute value but are only relative. The legs are designed for either fluidized or settled solids. 

Primary treatment (solid settling and removal) is required, secondary treatment (use of bacteria and aeration to enhance organic degradation) is becoming more routine, and tertiary treatment (filtration through activated carbon, applications of ozone, and chlorination) has been, or is being, implemented by all refineries. 

The second-stage (ammonia removal) effluent contained unacceptable levels of F and P and had to be subjected to third-stage lime treatment. This raises the pH from 8.5 to 11.4 and produces an effluent with concentrations of F and P equal to 25 and 2 mg/L, respectively. The hydraulic design parameters were a 15 min reaction time and a 265 gpd/ft (10.8 m /m /day) clarifier overflow rate. The resulting precipitated solids underflow concentration was 0.6% by wt. In all three stages, an anionic polymer was used to aid coagulation, solids settling, and effluent clarification. 

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