Evaluation of Remediation Methods for Soils Contaminated with Benzo[a]Pyrene

Abstract

Leakage of petroleum compounds around the Tehran Oil Refinery (TOR) for the past 30 years has caused oil pollutants to spread in a large area around this refinery, Therefore, remediation of the soil in this area is on the priority necessity. In the present paper, in order to obtain a better site perception, gas chromatography analysis and permeability tests were conducted on soil samples. Measurement shows the present concentrations of Benzo[a]Pyrene between 108 to 638 ppm that is 800 to 5000 times higher than the clean up level (120 ppb).Due to clayey texture and low permeability of the soils that ranges between 5.5×10-6 to 7.3×10-6 (cm/s), the low volatility of Benzo[a]Pyrene with Henry’s constant equal to 4.63×10-5 (dimless) and also a vapor pressure of 5.6×10-9 (mm Hg), physical methods such as soil flushing and soil vapor extraction were more costly and not suitable to treat TOR contaminations. Consequently, the phyto-remediation method via phyto-transformation and rhizosphere-bioremediation which are based on fragmentation of contaminants was found to be more compatible with geotechnical characteristics of the area in the south of (TOR), and was selected as the most appropriate method.