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

Abstract

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).

Microbubble transport in water‐saturated porous media

“…Microbubbles have larger interfacial area, longer life time, and higher concentration. All these features increase the degree of contact between the injected air and the contaminated soil, and thus enhance oxygen transfer efficiency in groundwater bioremediation [Li et al, 2014b;Tsai et al, 2007]. Our scaling solutions for the bubble plume development will help to estimate the residence time of bubbles in porous media.…”

“…Thus, injection of microbubbles increases the degree of contact between the injected bubbles and the contaminated soil. All these features enhance efficiency in groundwater bioremediation by promoting aerobic conditions for bioreactions and contaminant sorption [Li et al, 2014b;Tsai et al, 2007]. Furthermore, buoyant rise of the microbubbles may allow them to effectively access regions of (a) Snapshot of laboratory setup; (b) a typical bubble plume developed before the breakthrough (transient state, t < t*), the plume width (W top ) at the flume top was illustrated in yellow line; (c) calculated REV-averaged gas volume fraction distribution based on the bubble plume image shown in Figure 2b, with the solid black line showing the defined edge of the bubble plume.…”

Application research of micro and nano bubbles in water pollution control

“…It is nearly three times larger than air micro-nano bubbles, and the dissolved oxygen enhances durability for the longest, 16 times longer than air micro-nano bubbles. Li [7] et al found that when the particle size of the bubble is between 500 nm and 100 μm, the dissolved oxygen increases faster and the dissolved oxygen peak is higher. Adding surfactant in water can reduce the bubble size, reduce the oxygen transfer efficiency, and prolong the bubble stagnation time, increase bubble interface charge.…”

Direct catalytic oxidation and removal of NO in flue gas by the micro bubbles gas–liquid dispersion system

“…Negatively charged ions (such as OH − ) in water are prone to be adsorbed on the surface of MBs, so MBs carry some negative charges [6,7]. As the bubble diameter reaches micrometers or even nanometers, the surface tension of the gas-liquid interface compresses the bubbles, thus increasing the specific surface area of bubbles and the oxygen transfer efficiency between gas and liquid [8]. The diameter of MBs is small and the bubble pressure is high.…”