Field Demonstration of In Situ Remediation of Contaminated Groundwater Using Ozone Micro–Nano-Bubble-Enhanced Oxidation

The ozone micro–nano-bubble-enhanced oxidation (O3MNBEO) technology has shown great potential for organics-contaminated groundwater remediation in laboratory studies. However, few studies addressed its effectiveness in engineering practices as well as the impact on the groundwater environment. In this study, a field demonstration was conducted to investigate the efficiency of O3MNBEO in remediating groundwater contaminated by various organic compounds. The O3MNBEO technology exhibited high removal efficiencies ranging from 85 to 100% for benzene and significantly reduced the concentration of naphthalene, toluene, and petroleum hydrocarbons in 5-day remediation. Groundwater remediation using the O3MNBEO technology required less energy consumption and CO2 emissions. Moreover, O3MNBEO had no significant effect on groundwater pH and conductivity, and the oxidation–reduction potential (ORP) in groundwater and dissolved oxygen (DO) was substantially increased during the remediation process. The variations in ORP demonstrated a correlation with the contaminant concentration, which could serve as a potential indicator for assessing remediation progress. It is also worth noting that the presence of preferential seepage channels in the strata allows for the rapid migration of ozone MNBs, extending the reach of ozone MNBs. This study demonstrates that O3MNBEO is an efficient, practical, green, and sustainable technology that can be applied to in situ remediation of organics-contaminated groundwater.