Bubble formation by water release in nozzles---I. Mechanisms

Dupre, V.; Ponasse, M.; Aurelle, Y.; Secq, A.

doi:10.1016/s0043-1354(97)00435-1

Cited by 22 publications

(24 citation statements)

References 12 publications

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“…This fact was also viewed and confirmed by decreased of turbidity removal. These results are in agreement with the results reported by Carissimi [30] (www.lume.ufrgs.br/handle/ 10183/8974) who studied the flocculation of iron hydroxide colloidal precipitates (Fe(OH) 3 ) in an FGR of similar dimensions to those used in this work. These findings were confirmed by flocs characterization, which showed a higher incidence of aerated flocs (90-140 m/h) when using feed suspension flow rates of 0.24 m 3 /h compared to 0.12, 0.36, and 0.48 m 3 /h (Fig.…”

Section: Effect Of Q Ssupporting

confidence: 92%

“…A kaolin sample was procured from Cadam S/A, Brazil, and was of high purity (approximately, 100% of kaolinite evaluated by X-ray diffraction analysis as shown by Oliveira [17]). The mean particle diameter was determined to be 0.9 mm; the specific surface area measured by BET method was 17 m 2 /g, and the specific mass was 2.3 g/cm 3 . The kaolin is a particle model widely used in the flocculation research area to simulate the pollutant suspensions in water and wastewater treatments.…”

Section: Materials and Reagentsmentioning

confidence: 99%

“…Bubbles are formed by reducing the pressure of the water in the saturator vessel and are then forced to flow through needle valves or special orifices. Clouds of bubbles (30–70 µm) are produced immediately downstream of the flow constriction . These micro‐bubbles become attached or entrapped within the flocs, allowing the aggregates to rise and the fast separation of solids/liquids.…”

Section: Introductionmentioning

confidence: 99%

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Operating Parameters Affecting the Formation of Kaolin Aerated Flocs in Water and Wastewater Treatment

Oliveira

Rodrigues

Rubio

2013

CLEAN Soil Air Water

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The formation of aerated flocs (aeroflocs) and the main operating parameters involved were studied to improve the rapid solid/liquid separation by flocculation-flotation. A continuous flow system at the laboratory scale was used that coupled micro-bubbles dissolved air flotation and a flocs generator reactor (FGR). The aerated floc characterization technique was employed to characterize the aggregates obtained using a non-ionic polymer (920SH SNF-Floerger believed that, by maximizing operating parameters, improvements are achieved, mainly, both increasing the removal efficiencies and the design of the equipment that can be more compact requiring fewer areas than conventional units.

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Section: Effect Of Q Ssupporting

confidence: 92%

Section: Materials and Reagentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Operating Parameters Affecting the Formation of Kaolin Aerated Flocs in Water and Wastewater Treatment

Oliveira

Rodrigues

Rubio

2013

CLEAN Soil Air Water

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“…A clear advantage of such bubbles over larger ones was shown in various separation systems. It was found, in particular, that the flotation rate constant K f 1) varies as an inverse of d 3 b ; so the diameter of the bubbles usually used in such processes lies between 10 and 120 μm [8]. Fine bubbles are much more efficient in water aeration, which is strongly affected by the size of the bubbles.…”

Section: Introductionmentioning

confidence: 99%

Generation of Two‐Phase Air‐Water Flow with Fine Microbubbles

2016

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Aiming at the development of a low-cost technology for multipurpose water and surface treatment in the chemical industry and beyond, using microbubbles, a novel scheme of liquid-gas interaction within a specially designed bubble generator was tested. Its efficiency for the production of microbubbles with a size distribution in the micron range is confirmed. The basic element of the device is a vortex chamber with water supply through tangential ducts, while the gas (air) is introduced in a highly turbulent swirling flow of water in radial direction through the orifice in the gas supply duct, located on the chamber axis. Bubble diameters, bubble velocities in the pipe flow and effect of the output pressure on the bubble size distribution were studied.

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“…Therefore, it is confirmed that more bubble would be generated by increasing the superficial velocity in the inlet, and also the position where bubble breakup occurs moves downstream. Both cavity formation and dissolved gas content in water, therefore, determine the degree of bubble generation (Dupre et al 1998;Soubiran and Sherwood, 2000).…”

Section: Effect Of Flow Superficial Velocity On Nanobubble Generationmentioning

confidence: 99%

Bubble Size Effects in Coal Flotation and Phosphate Reverse Flotation using a Pico-nano Bubble Generator

Xiong¹

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Froth flotation is widely used in minerals industry. However, it is effective in a narrow size range, nominally 45-250 μm for coal and 10-150 μm for minerals. And the flotation performance of coal and minerals beyond this size range is not quite satisfactory. It is now recognized that the low-flotation efficiency of ultrafine particles is mainly due to the low probability of bubble-particle collision while the main reason for poor flotation recovery of coarse particles is the high probability of detachment of particles from the bubble surface. Pico-nano bubbles refer to tiny bubbles smaller than 0.5 μm, which can be produced using ultrasonic or hydrodynamic cavitation method. A fundamental analysis has shown that pico-nano bubbles will serve as a secondary collector, bridging between hydrophobic particles and conventional sized bubbles, which can significantly improve the flotation recovery of hydrophobic particles by increasing the probability of collision and attachment and reducing the probability of detachment. In order to obtain an optimal designed cavitation venturi tube for pico-nano bubbles' generation, different designs of cavitation venturi tubes were fabricated and tested in this study. The test results showed that maximum volume of pico-nano bubbles, 65% to 75%, and minimum mean pico-nano bubble size, 150 to 240 nm, were achieved at the medium ratio of the diameter of throat and outlet of the venturi tube (3 to 4), medium outlet angle (11°to 13°), high inlet angle (26° to 27°) and high ratio of the length of the throat and the diameter of throat (2.3 to 3). The laboratory-scale coal flotation tests showed that, the combustible material recoveries for coarse fractions,-700+355 μm, and ultrafines fraction,-75 μm, were remarkably increased in the presence of pico-nano bubbles in coal flotation. The maximum combustible recovery of 85 to 90% and minimum clean coal ash of 9.5 to 11% were achieved from 29.6% ash content of Pittsburgh No. 8 seam coal. At a given flotation combustible material recovery, more than half of the collector can be saved by using pico-nano bubbles in the column flotation. The frother dosage was also reduced to half. The laboratory-scale phosphate reverse flotation tests revealed that both the P 2 O 5 grade and P 2 O 5 recovery had been greatly improved in the presence of pico-nano bubbles. The column flotation using pico-nano bubble was capable of extending to float minus 75 m and 355-700 m particle size ranges much more effectively than column flotation with conventional sparger devices. The economic analysis performed in this study demonstrated that the application of pico-nano bubbles in both phosphate reverse flotation and coal flotation were economically feasible.

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Bubble formation by water release in nozzles---I. Mechanisms

Cited by 22 publications

References 12 publications

Operating Parameters Affecting the Formation of Kaolin Aerated Flocs in Water and Wastewater Treatment

Operating Parameters Affecting the Formation of Kaolin Aerated Flocs in Water and Wastewater Treatment

Generation of Two‐Phase Air‐Water Flow with Fine Microbubbles

Bubble Size Effects in Coal Flotation and Phosphate Reverse Flotation using a Pico-nano Bubble Generator

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