A critical review of the recent developments in micro–nano bubbles applications for domestic and industrial wastewater treatment

This review highlights the advantages of using micro–nano bubble (MNB) technology in various applications of wastewater treatment. Initially, the review examines key performance dissimilarities among different types of bubbles toward the treatment process. Specifically, a qualitative and quantitative meta-analysis of the effects of MNBs in the removal of target pollutants found in wastewater from different sources is conducted. A review on the MNBs characterization techniques to identify bubble size, size distribution, and accordingly bubble rising velocity as well as gas mass transfer rates, zeta potential, generation of free radicals, and bubble stability is also included. Moreover, the effect of bubble size on the efficiency of municipal and industrial wastewater treatment processes is evaluated. Finally, the applications of MNBs are investigated to explore their effectiveness in different wastewater treatment processes, such as ozonation, flotation/dissolved air flotation, aeration, and other processes. It is anticipated that the use MNBs could be a promising sustainable and low-cost wastewater treatment technology.