Water and wastewater treatment has always been a challenging task due to the continuous increase in amount and the change in characteristics of the poorly biodegradable and highly colored organic matters, as well as harmful micro-organisms. Advanced techniques are therefore required to successfully remove these pollutants from water before reuse or discharge to receiving water bodies. Application of ozone, which is a powerful oxidant and disinfectant, alone or as part of advanced oxidation process depends on the complex kinetic reactions and the mass transfer of ozone involved. Micro- and nano bubbling considerably improves gas dissolution compared to conventional bubbles and hence mass transfer. It can also intensify generation of hydroxyl radical due to collapse of the bubbles, which in turn facilitates oxidation reaction under both alkaline as well as acidic conditions. This review gives the overview of application of micro- and nano bubble ozonation for purification of water and wastewater. The drawbacks of previously considered techniques and the application of the hydrodynamic ozonation to synthetic aqueous solutions and various industrial wastewaters are systematically reviewed.

1. Introduction
 2. Water Disinfection
 3. Oxidation of organic and inorganicpollutants
 4. Color removal
 5. Application to control water pollutionin some other areas
 6. The Future of Micro- and Nanobubblesozonation
 Acknowledgment
 References

• Andinet Tekile(Department of Construction Environment Eng., University of Science and Technology, 과학기술연합대학원대학교, 건설환경공학과) | 테킬 안디넷
• Ilho Kim(Department of Construction Environment Eng., University of Science and Technology, Environmental and Plant Engineering Research Institute, Korea Institute of Civil Engineering & Building Technology, 과학기술연합대학원대학교, 건설환경공학과, 한국건설기술연구원, 환경플랜트연구소) | 김일호 Corresponding author
• Jai-Yeop Lee(Environmental and Plant Engineering Research Institute, Korea Institute of Civil Engineering & Building Technology, 한국건설기술연구원, 환경플랜트연구소) | 이재엽