Optimizing Micro/Nanobubble Ozonation: Unveiling Key Transition Points in Ozone Oxidation through Real-Time ORP Monitoring and Combined Ozone–Hydrogen Peroxide Process in Textile Wastewater Treatment

The treatment capacity of ozone advanced oxidation technology for industrial wastewater is limited due to ozone's inherent selective degradation of complex matrix components, leading the process from rapid oxidation to slow oxidation. Based on the influences of gas–liquid mass transfer characteristics and chemical reactivity on the rapid and slow oxidation processes of ozone, a synergistic process of ozone micro/nanobubbles (MNBs/O3) and H2O2 based on oxidation–reduction potential (ORP) is proposed to achieve deep removal of the ozone-resistant matrix in industrial wastewater. In deionized water, a second-order reaction kinetic method based on ozone and •OH exposure is used to assess the sensitivity of the ORP to identify the oxidation stage of MNBs/O3. Under different pH conditions, the feasibility of ORP real-time monitoring for reflecting the degradation efficiency of organic pollutants in actual dyeing wastewater effluent is further determined through batch experiments. The upward inflection point of the ORP effectively marks the end of the predominantly mass transfer-driven rapid ozonation process, which is likely the critical saturation phase point of ozone. The results further indicate that staged addition of H2O2 based on the upward inflection point of ORP in the MNB ozonation reaction is a more promising approach for deep removal of resistant pollutants.