Removal of polycyclic aromatic hydrocarbons from soil using surfactant and the white rot fungus Phanerochaete chrysosporium

Abstract

The bioremediation of soil contaminated with polycyclic aromatic hydrocarbons (PAH) is often limited by a low bioavailability of the contaminants. Non-ionic surfactants, such as Tween 80, when above their critical micelle concentration (CMC), can efficiently enhance the bioavailability of PAHs in contaminated soil by increasing solubility and dissolution rates. However, disposing of this micelle-contaminated spent washwater can be a major problem. The aim of this study was to combine surfactant soil washing techniques using Tween 80 with the versatile lignin-degrading system of the white rot fungus, Phanerochaete chrysosporium, to bioremediate PAH-contaminated soil. Approximately 85% (w/w) of a total of nine PAHs in an aged (1 month) contaminated soil (total PAH concentration=403.61 μgg-1) could be solubilized in a 2.5% (w/v) Tween 80 solution at a soil/water ratio of 1:10. The washwater was then catabolized by a 3-day-old culture of P chrysosporium under a stationary condition. The disappearance of most PAHs tested (molecular weight ≥ 178) correlated well with their ionization potentials and 66.4% (w/w) of the total PAHs in washwater with 2.5% (w/v) Tween 80 was catabolized after 11 days of culture. The catabolism was enhanced to 86% (w/w) using a lower concentration of 0.5% (w/v) Tween 80. The initial oxidation rate of total PAHs based on the first 4 days of culture remained almost constant at approximately 1.88 μgcm-3 day-1 when the Tween 80 concentration in wash water was increased from 0.5% to 2.5% (w/v). The combination of soil washing and white rot fungus catabolization of PAH using 2.5% (w/v) Tween 80 eliminated the total PAH concentration in the contaminated soil by 56.4% (w/w) after 11 days. The results suggest that PAH-contaminated soil may be cleansed by using a combination of surfactant soil washing and white rot fungus catabolism. (C) 2000 Society of Chemical Industry.