Experimental and numerical investigations on in situ chemical oxidation model for groundwater contaminated with petroleum hydrocarbons

The subsurface contamination by petroleum hydrocarbons (PHC) from leaking underground storage tanks, pipelines and refilling stations is one of the serious issues directly affecting the quality of groundwater. Application of advanced oxidation process (AOP) has been favoured for the remediation of petroleum contaminated sites due to the spontaneous redox reactions mediated by a strong activating agent. In this study, we propose a methodology for efficient injection of reagents by using two concentric PTFE tubes in a sand box model for simulating the groundwater flow, contaminant transport and in situ chemical oxidation (ISCO) using Fenton’s reagents (hydrogen peroxide and zero-valent iron particles). This injection method has proved to maximize the interaction of chemicals resulting in complete oxidation of petroleum compounds. An attempt has also been made to numerically simulate the mass transfer and transport of petroleum hydrocarbons incorporating the impact of spontaneous mass transfer by means of numerical methods. It is expected to have significant difference in interface mass transfer between free phase (oil) and water leading to increased exposure of residual oil phase, thereby enhancing the complete mass removal. The presence of soil organic matter (SOM) is found to be enhancing the activity of Fenton’s reagents as well as increasing the adsorption of hydrophobic organic compounds.