Efficient Removal of Dissolved Organic Matter via a Hybrid UV/O3 Micro-Nano Bubble Process

Removing trace amounts of dissolved organic matter (DOM) has always been a significant issue in the field of environmental science and engineering. Herein, a UV-coupled O3 micro-nano bubble (O3-MNB) system was constructed, demonstrating superior efficiency in eliminating DOM compared to bulk O3-MNB oxidation and direct UV photolysis. Various advanced analytical techniques, including in situ electron paramagnetic resonance, Fourier transform infrared spectroscopy and three-dimensional excitation–emission matrix, were employed to reveal the mechanism of the reaction process. Benefiting from the abundant interfacial area and enhanced mass transfer efficiency provided by the micro-nano bubbles, along with the simultaneous generation of reactive oxygen species such as •OH through UV activation, the UV/O3-MNB system demonstrates excellent performance in removing DOM, and more than 90% of the mineralization rate was achieved after 1 h reaction. Furthermore, the findings were verified using both municipal water and natural surface water, and the proposed system also shows advantages in energy consumption compared to direct UV irradiation and conventional O3 treatment, with an energy consumption of 25 kWh/mg dissolved organic carbon. This study innovatively integrates UV light with O3-MNB technology, offering novel insights for advanced water purification and providing valuable references for practical engineering applications.