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The introduction of synthetic, high molecular weight, water-soluble polymer flocculants was a turning point in tailings dewatering …
Lesson 29: Biosolids Thickening Calculations ...
Jul 10, 2008. #7. Oscillation has been manufacturing the Clarometer for over 20 years. It samples the centre well for settling time and so closely controls flocc addition. This helps stabilise the bed and control overflow turbidity. Our bed level device, the VBI, measures bed height through a turbidity probe mud diver.
Matching – Match the gravity thickener parts (A-E) with their proper description (1-5): C 1. Collects and removes effluent or thickener overflow. D 2. Slowly rotates to move the settled solids to the middle of the tank. A 3. Introduces the sludge into the thickener. B 4. Collects and removes floating debris. E 5. Provides gentle stirring or ...
Continuous separation tests of kaolinite-water suspensions in the laboratory thickener showed that a common maximum separation tolerance was less than 5.0% feed solids. With a safety factor, the maximum feed solids concentration was assigned as 3.0% for this study. Six (6) mathematical models were developed; two for each polymeric …
TABLE 3.4 Typical Dosages of Polymer for Thickening Sludge. Polymer Dosage. ... The most commonly used thickening processes are gravity thickening, dissolved air floatation thickening, gravity belt thickening, and rotary drum thickening. ... The strength of the thickener overflow or supernatant, as measured by suspended …
Polymer—A flocculant that consists of long chains of molecules that create bridges between solids particles when applied to the feed solids entering a thickening or dewatering unit. …
The tests coded as 01 were carried out with nickel concentrate thickener overflow water taken from the concentrator process, while the tests coded as 02 were carried out with the same thickener overflow water that had gone through the DAF treatment. The water samples were taken from the process on September 8, 10 and 11, …
concentrations that will be achieved by gravity thickening. Overflow Rate Another important consideration is the overflow rate. Overflow rates between 380 and 760 gpd/sq ft are typically used for primary solids. Overflow rates in the 100 to 200 gpd/sq ft range are used for thickening secondary solids. A high overflow rate can result
5.2.3 Air Floatation Thickening Air floatation units employ floatation of sludge by air under pressure or vacuum and are normally used for thickening the waste activated sludge. These units involve additional equipment, higher operating costs, higher power requirements, and more skilled maintenance and operation. However, removal
Solid–liquid separation of tailings slurries in gravity thickeners relies on the efficient mixing of slurry and dilute polymer flocculant solutions within the feedwell. Computational fluid dynamics (CFD) can provide predictions of solids distribution, liquor velocity and shear rate within a feedwell, and with the incorporation of an adsorption …
The flotation process in sludge thickening is in principle similar to the flotation for pretreatment of wastewater. In the flotation process, air is injected into the sludge tank from the bottom under pressure and a large amount of air bubbles disperse into the sludge, attach themselves to the sludge solids and float them to the surface of the ...
Suppliers indicate a degree of excess sludge thickening of between 3% and 6% without polymer dosage, but with polymer addition usually 1 to 1,5 kg/kg/DS the …
Dissolved air flotation (DAF) provides thickening of sludges (i.e. thickens the sludge) by encouraging the solids to float to the surface by their attachment to rising air bubbles. ... Polymer dosing at 2−5 g …
Flotation is a common mineral processing method used to upgrade copper sulfide ores; in this method, copper sulfide mineral particles are concentrated in froth, and associated gangue minerals are separated as tailings. However, a significant amount of copper is lost into tailings during the processing; therefore, tailings can be considered …
Thickener modernizations, upgrades and retrofits Restore your thickener to its original condition or upgrade for increased performance. Improve performance and extend the life of equipment by upgrading your aged thickener. The thickener bridge and mechanism are often upgraded in conjunction with the entire feed system. Upgrading these
The thickener underflow density increased (from 1586.8 to 1625.7 kg/m 3) and the overflow turbidity reduced (from 57.7 to 41.6 NTU) with increasing the slurry pH (from 8.1 to 11.2). Increasing the flocculant dosage (from 8 to 13 g/t solid) was associated with a rising in the thickener underflow density (from 1589.1 to 1628.8 kg/m 3 ) and a ...
Dissolved air is the most common type of flotation gas used in potable water treatment. The dissolved air flotation (DAF) process mixes a clarified stream from the outlet of the unit with air at 3–9 bar, to produce a supersaturated (compared with saturation at atmospheric pressure) solution of air in water.
The flocculation effect of tailings has an important influence on the turbidity of thickener overflow and the solid-liquid separation effect of tailings slurry. However, …
the thickener. If the operator was unable to immediately react to the situation with a polymer dosage, the material did not settle properly, resulting in a burst of solids to the overflow. Because the overflow was re-circulated backwards in the process as flotation spray water, the flotation performance was also disrupted
Effect of flocculants injection points on thickeners overflow turbidity (flocculant: 8 g/t; pH = 8.1). The results suggest that the underflow density and overflow …
An alternative to gravity thickening is dissolved air flotation. Thickening is the process by which biosolids are condensed to produce a concentrated solids product and a relatively solids-free supernatant (the relatively clear water layer between the sludge on the bottom and the scum on the surface of a tank or basin, an anaerobic digester, or ...
behaviour in the bulk of the thickener and therefor e on through-put, underflow density and overflow clarity. Another flow related phenome non of importance is natural dilution, the extent of ...
Beginners guide to thickeners. Thickening is a process where a slurry or solid-liquid mixture is separated to a dense slurry containing most of the solids and an overflow of essentially clear water (or liquor in leaching processes). The driving force for the separation is gravitational, where the differences in phase densities drive the ...
Employing a combination of two types of polyelectrolyte might become necessary to enhance both the settling rate of the flocs and the water clarity of a fine-particle suspension in a high-capacity thickening process. The sequence of addition, mixing, type and dosage of polymer all affect the overall performance and capacity of a thickening …
The downflow rate is analogous to the overflow rate used for sedimentation tanks and is defined as the total flow into the unit divided by the effective plan area of the flotation unit. ... Thickening of float solids occurs principally by drainage of interstitial water from the float above the water level. ... polymer was dosed to the influent ...
Applying polymer prior to a thickening or dewatering process is also called "conditioning". Conditioning with polymer is often a requirement for the thickening or dewatering equipment to successfully operate. POLYMER TYPE Polymer is supplied in three …
The gas formed will cause the flotation of the solids in the thickener. Chemicals like chlorine (CI 2) need to be added to inhibit the biological activity. A well operated thickener will have a solids recovery of about 95% [3]. Design of Thickeners The thickening process takes place in a settling tank with long-enough solids retention time.
Dissolved air flotation (Section 7.18) is sometimes used in waterworks sludge thickening (Haubry, 1983). Each thickener should have a dedicated feed pump of the progressive cavity type. Desludging can be initiated by sludge blanket level and terminated after a pre-set time, or when the solids concentration in the discharge measured in the ...
Conventional or High Capacity Thickeners: A Better Choice to Make? - 911 MetallurgistThis pdf document compares the advantages and disadvantages of conventional and high capacity thickeners in mineral processing plants. It discusses the factors that affect the selection of the best thickener type and size for a given application. It also provides …
TR189 states that continuous polymer thickening can produce sludges with 5%–20% DS from any practical solids concentration feed, with recovered water turbidity of 4–8 FTU. More precisely, it predicts the following performance for a surface loading on the thickener of 1.5 m/h on the following basis:
First determine the surface area of the thickener: = 0.785 x (40 ft) To determine the solids applied, you will use the "pounds" formula where the concentration is 1.8%: *Hint: the flow is given in gpd since the "concentration" is given in percent instead of mg/L. Remember that 1% = 10,000 mg/L. Solids applied, lb/day = Biosolids, % x Flow, gpd ...
Feed slurry enters at Thickener #1 and wash water at Thickener #3. Flowing counter to each other, the overflows collect more of the valuable solution and the underflows more of the waste solids. Emmett & Dahlstrom explained that the controlling factors of CCD are: Number of stages (number of thickeners) Liquid in overflow versus underflow
The primary clarifier's underflow and the waste activated sludge from the COP Clarifier are treated with polymer and then fed into a thickener to thicken the solids. The thickener effluent overflow is recycled back into the primary clarifier. The thickener's underflow is again treated with polymer and sent to a filter press for dewatering.
re-circulated backwards in the process as flotation spray water, the flotation performance was also disrupted by the solids covered with polymers. Figure 3 Relative distribution of …
4. Sludge thickening Purpose – to increase solid content of sludge by removing a portion of the liquid fraction Thickening is generally accomplished by physical means, including co-settling, gravity settling, …
Biological flotation adopts the chemistry of nitrification and denitrification for genera- tion of fine nitrogen and carbon dioxide bubbles in its flotation thickening process reac- tors for …
