Prediction and Experimental Study of Mass Transfer Properties of Micronanobubbles

Abstract

In order to study the mass transfer efficiency of micronanobubbles (MNBs), an equation of the volumetric mass transfer coefficient (k L a) was proposed based on theory and dimensionless numbers. It was verified by experimental data from different literature sources. Then, the k L a in an MNB column was measured under the conditions of different salt concentrations. The test results showed that the equation could successfully predict the k L a in an MNB column of not only this research but also other literature. In the MNB column, when the salt concentration increased from 0.0 to 3.0 g/L, the values of the Sauter mean bubble diameter (d BS ), gas holdup (ε), and specific gas−liquid interface (a) had remarkable changes. Salt coalescence suppression was the governing effect for the hydrodynamic variables, and it was more prominent for common bubbles than for MNBs. The value of the k L a in the MNB column was an order of magnitude larger than that in the common bubble column, and it was improved significantly in salt solution. Hydrodynamic variables were dominant effects of mass transfer. Overall, the prediction equation of the k L a provides a reference for the mass transfer rate calculation of MNBs.

A comparative study of removal efficiency of organic contaminant in landfill leachate-contaminated groundwater under micro-nano-bubble and common bubble aeration

“…Pressurized dissolution type MNB generator (XZCP-K-1.1, Yunnan Xiazhichun Environmental Protection Technology Co., Ltd, China) was used for MNB aeration. The method of MNB aeration was described in previous literature (Bai et al, 2021). CB was generated by the tube with a diameter of 3 mm.…”

“…The fast increase rate of DO, the great DO peak value and the higher oxygen utilization e ciency in groundwater during MNB aeration resulted from high mass transfer e ciency of MNB. In order to investigate the mass transfer e ciency of MNB and CB aeration, the volumetric oxygen transfer coe cient (k L a) of MNB and CB were calculated by the following equation (Bai et al, 2021):…”

“…In membrane bioreactor, oxygen MNB markedly enhanced the removal e ciency of contaminants compared with conventional air aeration, and the pure oxygen provided a high dissolved oxygen condition which would in uence the biomass activity by affecting the enzymatic activities (Zhuang et al, 2016). Due to the characteristic of high mass transfer e ciency (Bai et al, 2021;Xiao and Xu, 2020), the strong of bubble migration (Kristen et al, 1993;Li et al, 2014) and high pollutant degradation e ciency, MNB aeration has become a promising measure for wastewater remediation.…”

Removal efficiency of organic contaminants in landfill leachate contaminated groundwater under oxygen micro–nano bubble aeration

“…During the MNB aeration, 20 L contaminated groundwater was fed into the bubble column, and the oxygen flow rate was controlled at 1.8 L min −1 . 29 The DO concentration of groundwater was recorded using a DO meter (YSI ProSolo). The DO meter read the value every second.…”

“…The high DO peak value indicated that MNB aeration effectively increased the DO concentration of groundwater. To assess the oxygen mass transfer efficiency of the oxygen MNB aeration, the oxygen volumetric transfer coefficient (k L a) was calculated by the following equation: 29 dC* dt…”