An Experimental Feasibility Study on the Remediation of TPH and Lead Contaminated Soil at the Busan Train Station Using Soil Flushing and Chemical Oxidation

This study aimed to evaluate the applicability and feasibility of in-situ remediation technologies, especially soil flushing and chemical oxidation, to remediate contamination by total petroleum hydrocarbons (TPH) and lead at a site located at the Busan train station. The presence of above-ground structures and underground burials imposed significant constraints on evacuation operations.Soil samples were collected from areas contaminated with lead and TPH, followed by a series of laboratory experiments designed to identify an effective in-situ remediation process tailored to the site’s specific conditions. The soil was characterized as sandy loam, with initial contaminant concentrations measuring 3,250 ± 487 mg/kg for TPH and 1,050 ± 94 mg/kg for lead. Notably, as the soil particle size decreased, the concentrations of TPH and lead increased. A TPH removal efficiency of 31.2% was achieved using 5% hydrogen peroxide without a catalyst, indicating that higher concentrations of hydrogen peroxide enhanced TPH removal rates. A sequential/combination process using Tween 80 and hydrogen peroxide, considering field conditions with heterogeneous soil conditions and various petroleum-based pollutants, proved appropriate for the remediation of TPH-polluted sites.Following treatment with citric acid and hydrogen chloride, an increase in the exchangeable fraction of lead was observed, while the residual fractions in lead-contaminated soil remained relatively low. The leaching of lead utilizing citric acid was found to be effective in terms of its environmental impact post-remediation, despite hydrochloric acid demonstrating the highest removal efficiency among the tested washing agents.Column tests demonstrated that the removal efficiencies of 0.1% Tween 80 and 0.1 M citric acid applied over 10 pore volumes (PV) of contaminated soil were 38.9% for TPH and 43.7% for lead, respectively. The results of this research provide useful technical data for conducting full-scale remediation processes in the field. Keywords: Soil flushing, Chemical oxidation, Train station, TPH, Lead