Application of Steam Enhanced Extraction method on BTEX contaminated soil in a Nigerian petroleum depot and Automobile workshop sites in Ilorin metropolis, Nigeria

Abstract

The contamination of soil in the environment is a natural consequence of industrialization and urbanization. Organic chemical pollutants dissolve into groundwater, absorb and adsorb into soil grains. Benzene, toluene, ethylbenzene and xylene (BTEX) are major causes of contaminated soil. This is due to fuel leakages or spillages, various forms of hydrocarbon burning/combustion and land disposal petroleum base oil. Contaminated soil samples were excavated from two different locations within the Ilorin metropolis; pipelines and products marketing company, a Nigerian petroleum depot, Ilorin depot and auto mechanic workshop of over ten years. Steam enhanced extraction method was employed through injection of steam to contaminated soil from steam generator into soil pot where contaminated soil was placed. The condensation of steam on soil particles provides energy to release desorbed contaminants molecules from the soil and the mobilized contaminants vapor was transferred into the recovery pot via the pipe that was connected to the soil pot. After the remediation process, the steamed soil samples were taken to the laboratory where the sonication extraction technique was used to extract the contaminants (BTEX) from the steamed soil samples of 30, 60 and 90 minutes respectively. The extract from the steamed soil samples of 30, 60 and 90 minutes was subjected to Gas Chromatography fitted with flame ionization detector analysis to determine the exact amount of BTEX removed after the remediation process. Pre-treated soil sample of auto mechanics workshop was found to be 4.5004 x 10-1 mg/kg and post-treated soil samples were found to be 1.8164 x10-1 mg/kg, 8.7519 x10-1 mg/kg and 5.7006 x10-2 mg/kg for 30, 60 and 90 minutes respectively after remediation process while Pre-treated soil sample of a Nigerian petroleum depot was found to be 6.6049 x 10-1 mg/kg and post-treated soil samples were found to be 2.9320 x10-1 mg/kg, 1.9855 x10-1 mg/kg and 1.0237 x10-1 mg/kg for 30, 60 and 90 minutes respectively after the remediation process. This study established the effectiveness of the remediation process of hydrocarbon contaminated soil using steam enhanced extraction method an In situ remediation technique