Remobilization of Polycyclic Aromatic Hydrocarbons (PAH) contaminated soils with a new biosurfactant

Polycyclic aromatic Hydrocarbons (PAH) are organic pollutants released into the environment by combustion processes; Due to their high sorption capacity, soils constitute their main environmental sink. PAH are hydrophobic and weakly biodegradable, moreover they are toxic and considered as potent human carcinogen. Various technologies are used for the remediation of PAH-contaminated soils, but they are not cost effective and may be hazardous for the environment. Some recent studies suggest that the use of biosurfactants is a promising method that enhances the removal of PAHs from soils. This study investigates the properties and the impact of a new biosurfactant, on the mobilization of three PAH (fluorene, fluoranthene and pyrene). The biosurfactant seems to be weakly sorbed on the soil studied. Solubilizing effects have been studied by the Molar Solubilization Ratio (MSR). In the ternary mixture, the less hydrophobic PAH (fluorene) favors the micellar solubilization of the most hydrophobic one by decreasing interfacial tensions. The soil column studies revealed that the biosurfactant was rapidly efficient. Results obtained in dynamic studies were consistent with those obtained in static studies. This work also investigated the effect of the contamination level on PAH remobilization. The study reveals that PAH solubilization increases with the contamination level until micelle saturation. The percentage remobilized depends on the contaminant studied and the content of organic matter rate. As a matter of fact, for the soil containing the higher OM rate, remobilization follows physicochemical properties of the PAH. For the soil containing less OM, the mineral fraction seems to play a significant role on PAH adsorption. (author)