Water Purification Using the Adsorption Characteristics of Microbubbles

Yoshida, Akira; Takahashi, Osamu; Ishii, Yorishige; Sekimoto, Yoshihiro; Kurata, Yoshiyuki

doi:10.1143/jjap.47.6574

Cited by 45 publications

(21 citation statements)

References 2 publications

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“…Microbubbles with 30 lm radius were first found by Turner (1961) in water and they were found to exist for long periods of time, contradictory to classical theory. The significant factor determining water purification effectiveness of MNB technology is the surface area, which relates to the pollutant adsorption on the bubble surface (Yoshida et al, 2008). Micro-nano bubbles are found to be negatively charged under a wide range of pH conditions (Takahashi, 2005).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Micro‐Nano Bubbles and Potential Application in Groundwater Bioremediation

Song

et al. 2014

Water Environment Research

119

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Content of oxygen in water is a critical factor in increasing bioremediation efficiency for contaminated groundwater. Micro-nano bubbles (MNBs) injection seems to be an effective technique for increasing oxygen in water compared with traditional air sparging technology with macrobubbles. Micro-nano bubbles have larger interfacial area, higher inner pressure and density, and lower rising velocity in water, superior to that of macrobubbles. In this paper, MNBs with diameters ranging from 500 nm to 100 lm are investigated, with a specific focus on the oxygen mass transfer coefficient from inner bubbles to surrounding water. The influence of surfactant on the bubbles formation and dissolution is studied as well. The stability of MNBs is further investigated by means of zeta potential measurements and rising velocity analysis. The results show that MNBs can greatly increase oxygen content in water. Higher surfactant concentration in water will decrease the bubbles size, reduce the dissolution rate, and increase the zeta potential. Moreover, MNBs with greater zeta potential value tend to be more stable. Besides, the low rising velocity of MNBs contributes to the long stagnation in water. It is suggested that micro-nano bubble aeration, a potential in groundwater remediation technology, can largely enhance the bioremediation effect. Water Environ. Res., 86, 844 (2014).

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Section: Introductionmentioning

confidence: 99%

Characteristics of Micro‐Nano Bubbles and Potential Application in Groundwater Bioremediation

Song

et al. 2014

Water Environment Research

119

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“…This mechanism induces intense turbulent pressure fluctuations leading to bubble breakup, as opposing to the bubble internal pressure and surface tension. An additional effect in Venturi MBGs is the saturated-vapour pressure in the divergent section, which can result in cavitation [21].…”

Section: Introductionmentioning

confidence: 99%

Initial Results from the Experimental and Computational Study of Microbubble Generation

Basso¹,

Hamad²,

Ganesan³

2019

Proceedings of the 4th World Congress on Momentum, Heat and Mass Transfer

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A novel design of microbubble aeration is proposed to increase dissolved oxygen (DO) levels in water, by reducing the mean bubble diameter distribution down to the 20 -50 µm range. Microbubble generators (MBGs) find application in aquaculture farms, where water oxygenation is crucial for sea lives and for disinfection through free radicals. A Venturi MBG is taken as baseline design for comparison with previous literature, to understand the pressure-recovery mechanism responsible for bubble breakup. Based on Venturi performance, a helicoidal body -at three different pitch angles -is added ahead of the throat to create sufficient swirling motion, with the aim of intensifying turbulent pressure fluctuations. Results from a validated Computational Fluid Dynamics (CFD) setup and flow visualisation are compared to assess the accuracy of present experimental results, in terms of MBG performance at different volumetric qualities. Backlight imaging and binary processing are implemented to estimate microbubble distributions. Probability distribution and mean diameter plots show an initial disagreement of experimental data from the literature and present predictions. This is presumably attributed to a possible improvement to be done, in terms of light illumination and the use of a microscopic lens, which can better spot small microbubbles. Furthermore, results from CFD show a reduction in the mean diameter when using a helicoid pitch angle of 20 degrees. Of particular interest is a mean diameter near 25μm at very low volumetric quality. By contrast, the configuration at pitch angle of 30 degrees gives a distribution with mean diameter near 70μm, for same volumetric quality. Although this paper only focuses on the bubble diameter aspect, DO measurements coupled with the analysis of microbubble distributions will reinforce authors assumption that small microbubbles represent the optimal condition to maximise water aeration and to enhance treatment of organic particles.

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“…The Venturi-type bubble generator is similar to the pressurized dissolution type in the bubble generation method and has been widely used due to its simple structure. Yoshida et al [8] found that microbubbles were generated through the collision of a gas with the pressure wall formed by a shock wave. Yin et al [9] conducted an experimental study on the bubble size distribution in the turbulence flow for the Venturi-type bubble generator and proved that the averaged bubble diameter has a dependence on the Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

Bubble Size and Bubble Concentration of a Microbubble Pump with Respect to Operating Conditions

2018

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Abstract:The present paper describes some aspects of the bubble size and concentration of a microbubble pump with respect to flow and pressure conditions. The microbubble pump used in the present study has an open channel impeller of a regenerative pump, which generates micro-sized bubbles with the rotation of the impeller. The bubble characteristics are analyzed by measuring the bubble size and concentration using the experimental apparatus consisting of open-loop facilities; a regenerative pump, a particle counter, electronic flow meters, pressure sensors, flow control valves, a torque meter, and reservoir tanks. To control the intake, and the air flowrate upstream of the pump, a high precision flow control valve is introduced. The bubble characteristics have been analyzed by controlling the intake air flowrate and the pressure difference of the pump while the rotational frequency of the pump impeller was kept constant. All measurement data was stored on the computer through the NI (National Instrument) interface system. The bubble size and concentration are mainly affected by three operating parameters: the intake air flowrate, the pressure difference, and the water flowrate supplied to the pump. It is noted that the operating conditions that can most effectively generate microbubbles in the range of 20 to 30 micrometers are at the pressure of 5 bar and at the air flowrate ratio of 4.0 percent for the present pump. Throughout the experimental measurements, it was found that the pump efficiency changed by less than 1.2 percent, depending on the intake air supply. The performance characteristics of microbubble generation obtained by experimental measurements are analyzed and discussed in detail.

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Water Purification Using the Adsorption Characteristics of Microbubbles

Cited by 45 publications

References 2 publications

Characteristics of Micro‐Nano Bubbles and Potential Application in Groundwater Bioremediation

Characteristics of Micro‐Nano Bubbles and Potential Application in Groundwater Bioremediation

Initial Results from the Experimental and Computational Study of Microbubble Generation

Bubble Size and Bubble Concentration of a Microbubble Pump with Respect to Operating Conditions

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