Jar sedimentation

In the current context the results of a sedimentation test are used in equipment selection to eliminate unsuitable equipment from a sometimes lengthy list. The objective is to determine the initial (constant) rate of settling, clarity of the supernatant liquid and the final proportion of sludge. 

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Determine the solids concentration in the slurry sample before commencing the jar sedimentation test(s). 

Figure 4.9 Plot of suspension-supernatant interface height vs. time data for a typical laboratory scale jar sedimentation experiment (also a plot of the data for Example 4.4).

Although comprehensive descriptions of equipment selection are given in this chapter the specifics of data analysis and equipment simulation are presented elsewhere. Chapter 4 provides practical methodologies, theories and principles that underpin the analysis of filtration, jar sedimentation and expression tests. Chapters 6 and 7 respectively present extensive descriptions of batch and continuous filter simulations, however, an introduction to simulation is described here. 

The duty specification, jar sedimentation and filtration tests enable the slurry settling and filtering characteristics to be broadly classified, and a selection problem to be specified through a series of letter codings. In order to select and rank equipment from this information it is necessary to provide charts and/or tables which relate equipment performance to the letter codings. Comparisons between the user defined specifications and the tables/charts enable the selection process. 

Section 5.1.1 detailed the charts and data tables which exist in the public domain. While they provide an insight into the application and operation of particular classes of equipment, they rarely address the problem of how a class of equipment is correctly chosen in the first instance. Generic classes of equipment have been described in Chapter 1 and previously identified by Davies (1965), Moos and Dugger (1979), Purchas (1981), Purchas and Wakeman (1986), Tarleton and Wakeman (1991) and Wakeman and Tarleton (1991a). In Table 5.1 these generic classes are reiterated and associated with the letter codings for duty specification, jar sedimentation and... 

The data analysis module facilitates interactive analysis of leaf filtration, jar sedimentation and piston press test data. Calculations are performed in a hierarchical manner using the available information if some data are not measured then FDS performs the best possible analysis using approximations. The results of an analysis can be used to refine (shorten) a list of selected equipment and/or provide scale-up information for equipment simulation. 

The Data Analysis module of FDS facilitates the interactive analysis of constant pressure and constant flow filtration, jar sedimentation and piston press (expression) tests the procedures are computer software implementations of the analysis techniques described in Chapter 4. Data obtained at the laboratory, pilot and even full scale can be analysed in a consistent manner... 

Jar sedimentation time (t) vs. suspension/supernatant interface height (//,)... 

Constant pressure filtration ylV vs. Vf Constant flow filtration t vs. Afy Constant pressure expression — AL/AVt vs. t Jar sedimentation vs. t... 

Vertical line cursors are used to identify a linear or transition region on the Characteristic Plot and these are initially positioned by FDS. However, the user has facility to interact with the software and move the cursors as appropriate in order to overcome their potential misplacement due to data scatter. In this way the analysis can be amended as many times as required and optimised. During the analysis of a jar sedimentation test a third, horizontal line cursor is used to specify the final height of sediment, which is particularly useful when a test is not continued to equilibrium. In the case of a piston press analysis, and in accordance with the recommend procedure described in Section 5.5, additional representations of test data are shown for the filtration and consolidation phases to check the choice of transition between the two. For example, in Figure 5.12 the correct transition has been identified on the Characteristic Plot such that the resultant tjIVj vs. Vf plot is linear throughout and the consolidation ratio U vs. (consolidation time, exhibits an initial linear portion. In Figure 5.13 the transition point has been deliberately chosen too far to the left on the Characteristic Plot such that the vs. plot exhibits an incorrect S shape. 

The jar sedimentation experiment is analysed using a similar general procedure to the filtration experiment. In this case, however, the interactive Characteristic Plot shows suspension-supernatant interface height V5. time data. An additional horizontal cursor allows the final sediment height to be interactively defined by the user (see Figure 5.16). For the experimental data in Table 5.3, the results show a settling rate = 0.25 cm s and a proportion of sludge = 33%. 

Figure 5.1 6 Interactive graphical display screens from FDS for the constant pressure filtration (left) and jar sedimentation (right) tests described in Example 5.1.

The consistent analysis of filtration, expression and jar sedimentation tests to allow the accurate determination of the parameters required for process simulation and the basic information needed for equipment selection... 

Proportion of final sediment height to initial height of suspension in a jar sedimentation test... 

Anaiysis offiiter ieaf test resuits, jar sedimentation test data, and expression data... 

Figure 2.6 Sedimentation zones during slurry settling (The Jar Test ). A, initial uniform concentration, B, zone of increasing concentration, C, sediment or sludge, D, clear liquor...

For determination of activities of " Th in sediments by gamma spectrometry, the sediment (-100 g) is dried, ground and sealed in sample jars for counting. Activities are determined using a modification of Equation (3) in which the E term is not included, and V is replaced by the sample mass. Counting efficiencies are determined by counting sediment standards of known (and equilibrium " Th) activity. 

Acidified water from jar C was siphoned with a turkey baster into jar B until the water covered the sediments. The contents of the jar were again left to sit in warm water, this time about 30 minutes. 

Sediment samples were collected with a dredge-type sampler from a boat and also with the aid of a diver. One quart glass jars with aluminum foil-lined caps were used for the sediment samples after collection they were placed in a box containing dry ice. The composition of the river bottom sediments varied from coarse sand (>600m) in the center of the river to coarse and fine silt toward the banks. 

In procedure 1, approximately 900 mL of fuel is placed into a 1-L clear glass jar and is examined visually for clarity. The sample is then swirled and examined for visual sediment or water drops below the vortex. 

These collectors are used primarily for large particles (> 2.5 /im), that is, those in the coarse particle range. They include collection by gravitational sedimentation (e.g., dustfall jars) as well as by centrifugal... 

Coring Strategy. Sediment cores were collected with a thin-walled polycarbonate tube fitted with a piston and operated from the lake surface by rigid drive rods (30). This device recovers the very loose uncompacted sediment surface as well as deeper strata without disturbance or displacement (core-shortening, cf. refs. 31 and 32). Core sections were extruded vertically from the top of the tube into polypropylene collection jars, transported on ice to the laboratory, and stored at 4 °C until analysis. 

Let the iodine mixture sit long enough for the sediment to settle and discard as much of the clear liquid as possible before filtering the sediment. Hold the filter cone over a clean, wide-mouthed, 1-quart glass jar and pour the liquid containing the sediment into it. The sediment is your explosive. The small amount you have just made will go much farther than you realize. 

Tartar from Wine Lees, the Bitter Recrement or Earthy Sediment which is found in the bottom and at the sides of jars or Flagons. 

Example 8.5 A wastewater containing [C ] = 25 mg/L of phenol is to be treated using PAC to produce an effluent concentration [C] = of 0.10 mg/L. The PAC is simply added to the stream and the mixture subsequently settled in the following sedimentation tank. The constants of the Langmuir equation are determined by rnnning a jar test prodncing the resnlts below. The volnme of waste snbjected to each test is one liter. If a flow rate of Q of 0.11 mVs is to be treated, calcnlate the quantity of PAC needed for the operation. What is the adsorption capacity of the PAC Calcnlate the qnantity of PAC needed to treat the inflnent phenol to the ultimate residual concentration. 

The start of sedimentation t = 0 equals point I + BC on the curve. The knowledge of the total flow rate through the sampling cell and of the turbidities in H and I enables us to calculate the flow rate of sample drained away from the jar. Knowing the geometry of the jar, the drop of water level in the flocculator... 

The coagulation process was investigated by the jar-test method with the following parameters rapid mix (G = 200 s ) for 2 minutes, flociUation (G = 20 s ) for 20 minutes, and sedimentation for 30 minutes. After the sedimentation process had been completed, determinations were carried... 

Based on laboratory jar testes, the optimum pH range for flocculation-destabilization was defined. Asbestiform fiber reduction during effluent treatment, after flocculation-sedimentation and filtration, was also evaluated. 

Pour. he filtorod liquid into a stew pot or something similar and renew the filter and fill the jar again. Dispose of that filter and continue until there is no liquid or sediment in the Can,... 

In an incubation performed to test for possible toxaphene degradation in organic-rich lake sediments, a jar is filled with 2 kg of dry sediment 3 liters of water 0.1 g of nitrate 0.2 g of iron oxyhydroxides, Fe(OH)3 and 0.2 g of sulfate. The mixture is initially bubbled with air, toxaphene is incorporated at a concentration of 0.2 ppm, and the jar is sealed. Toxaphene is a mixture of compounds formed from the chlorination of camphene, and was once commonly employed as a pesticide. 

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