Ozone Micro-nano-bubbles Enhanced Groundwater Remediation Technology

Groundwater is an important water supply source in China,and now is facing more and more serious organic contamination issues;therefore,development of green and sustainable remediation(GSR)technology is of academic and practical importance.Ozone micro-nano-bubbles(MNBs)technology shows great potential in organicscontaminated groundwater remediation.Based on the state-of-the-art literature review,ozone MNBs enhanced technology is proposed for organics-contaminated groundwater remediation.A multi-scale testing system for ozone MNBs enhanced groundwater remediation technology was established.Model experiments were conducted to systematically investigate the properties of ozone MNBs and their behaviors during groundwater remediation.Field test was conducted to further study the processes of groundwater remediation by ozone MNBs.Furthermore,a theoretical framework for the process of in-situ groundwater remediation by ozone MNBs was developed,and a numerical model was developed to provide better understanding of the multi-field coupling behaviors during ozone MNBs enhanced groundwater remediation process.This research will promote the practical application of ozone MNBs technology in groundwater remediation.The established multi-scale testing system incorporates the measurement system,physical modeling facilities,and site remediation system.The measurement system can be used to study the physical and chemical properties of ozone MNBs through microscale measurement and macro-scale analysis.The physical modeling facilities can be used to study the behaviors of MNBs migration in soil and contaminant removal by ozone MNBs.The site remediation system can be used to conduct and monitor the in-situ process of ozone MNBs enhanced groundwater remediation.The results of the physical model tests indicated that ozone MNBs presented high mass transfer efficiency,large influencing zone,and remarkable remediation effect.MNBs could stay stable in water under different salinity conditions.MNBs improved the mass transfer efficiency of ozone for 3 times,and prolonged the half-life of dissolved ozone for 14 times,and provided sustained dissolved oxygen supply.Ozone MNBs greatly enhanced the treatment of organic contaminants,and presented remarkable contaminant-treatment efficiency under different p H and salinity conditions.Ozone MNBs showed significant treatment ability on wastewater that can hardly be treated by conventional technologies,and the treatment efficiency could be further improve by addition of hydrogen peroxide.Ozone MNBs could migrate with groundwater flow and showed significant hydrodynamic dispersion through pore-network and adsorption on soil particles.Therefore,MNBs presented large influencing zone and showed remarkable efficiency on groundwater remediation.The results of the field test indicated that ozone MNBs enhanced groundwater remediation is an environmental-friendly and efficient technology.Ozone MNBs could persist in groundwater to maintain high concentration of oxidants.MNBs could migrate with groundwater to reach large influencing area in both longitudinal and transverse directions.With the enhancement by hydrogen peroxide,ozone MNBs showed significant remediation efficiency on a TCE contaminated site,and the overall removal rate of TCE reached 99% after 6 days of treatment.Ozone MNBs enhanced technology showed considerable application potential in groundwater remediation.A theoretical framework for MNBs enhanced groundwater remediation was proposed,and multi-field coupling numerical model was developed to simulate the processes of in-situ groundwater remediation.Governing equations for mass transfer processes and contaminant removal processes were established,and the migration processes of ozone MNBs,dissolved ozone,and dissolved oxygen in groundwater were coupled,and the FEM numerical model was developed thereafter.The simulation results were in good agreement with model testing and field monitoring data,which indicated that the numerical model is reliable and could be used to guide practical implementation of ozone MNBs enhanced groundwater remediation technology.