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

The bioremediation of soil contaminated with polycyclic aromatic hydrocarbo ns (PAH) is often limited by a low bioavailability of the contaminants. Non -ionic surfactants, such as Tween 80, when above their critical micelle con centration (CMC), can efficiently enhance the bioavailability of PAHs in co ntaminated soil by increasing solubility and dissolution rates. However, di sposing of this micelle-contaminated spent washwater can be a major problem . The aim of this study was to combine surfactant soil washing techniques u sing Tween 80 with the versatile lignin-degrading system of the white rot f ungus, Phanerochaete chrysosporium, to bioremediate PAH-contaminated soil. Approximately 85% (w/w) of a total of nine PAHs in an aged (1 month) contam inated soil (total PAH concentration = 403.61 mug g(-1)) could be solubiliz ed in a 2.5% (w/v) Tween 80 solution at a soil/water ratio of 1:10. The was hwater was then catabolized by a 3-day-old culture of P chrysosporium under a stationary condition. The disappearance of most PAHs tested (molecular w eight greater than or equal to 178) correlated well with their ionization p otentials and 66.4% (w/w) of the total PAHs in washwater with 2.5% (w/v) Tw een 80 was catabolized after 11 days of culture. The catabolism was enhance d to 86% (w/w) using a lower concentration of 0.5% (w/v) Tween 80. The init ial oxidation rate of total PAHs based on the first 4 days of culture remai ned almost constant at approximately 1.88 mug cm(-3)day(-1) when the Tween 80 concentration in washwater was increased from 0.5% to 2.5% (w/v). The co mbination of soil washing and white rot fungus catabolization of PAH using 2.5% (w/v) Tween 80 eliminated the total PAH concentration in the contamina ted soil by 56.4% (w/w) after 11 days. The results suggest that PAH-contami nated soil may be cleansed by using a combination of surfactant soil washin g and white rot fungus catabolism. (C) 2000 Society of Chemical Industry.