Remediation of Gulf War Oil Spill Contaminated Soil by a Subcritical Water Extraction Process: Oil Removal, Recovery, and Degradation

• Published in: Soil & sediment contamination Vol. 27; no. 2; pp. 120 - 130
• Main Authors: Islam, Mohammad Nazrul, Taki, Golam, Jung, Yeon-Jae, Jung, Sun-Kook, Park, Jeong-Hun
• Format: Journal Article
• Language: English
• Published: Boca Raton Taylor & Francis 17.02.2018; Taylor & Francis Ltd
• Subjects: Acetone; Aromatic compounds; Contaminated soil; Continuous flow; Crude oil; degradation; Degradation products; Dielectric constant; Dielectric properties; Efficiency; Effluent treatment; Environmental degradation; extraction; Flow velocity; Green remediation; Gulf War; Oil pollution; Oil recovery; Oil removal; Oil spills; Organic soils; Organic solvents; Oxidation; Oxidizing agents; Persian Gulf War; Pollutants; Pollution control; Recovery; Remediation; Removal; Sediment pollution; Soil; Soil contamination; Soil pollution; Soil remediation; Soil treatment; Soil water; subcritical water; Temperature effects; Viscosity; War; Wastewater treatment; Water; Water flow; Water pollution; Water temperature; Water treatment
• ISSN: 1532-0383; 1549-7887
• DOI: 10.1080/15320383.2018.1432563

Due to the unique properties of subcritical water (marked change in water's dielectric constant and viscosity), the extraction by subcritical water offers a great opportunity to remediate soil contaminated with organic pollutants as an alternative and green remediation method. In this study, subcritical water extraction is proposed as an efficient remediation technique for the Gulf War oil spill contaminated soil. The subcritical water extraction experiment was carried out in a lab-scale continuous flow apparatus. The three major operating factors, temperature, time and water flow rate, were evaluated in terms of optimum removal efficiency. The results show that crude oil removal depended largely on water temperature, whereas an extraction run time higher than 1 h and a water flow rate higher than 1.5 mL/min marginally or negatively affected removal efficiency. During subcritical water treatment at 300°C for 1 h at a flow rate of 1.5 mL/min, removal efficiency was almost 95%. Under these operating conditions, the subcritical water treatment demonstrated a similar removal efficiency to those of organic solvents like acetone. In contrast, the efficiency of oil recovery decreased with an increase in extraction temperature, due to degradation by a water self-oxidizing agent. Several degradation products identified in the treated soil and in the effluent sample (which initially were absent in the contaminated soil) were oxygen-containing aromatic compounds, confirming the oxidation-degradation.