Release of polycyclic aromatic hydrocarbons from contaminated soils by surfactant and remediation of this effluent by Penicillium spp.

Studies in which surfactants have been employed to increase the bioavailabi lity of soil-bound polycyclic aromatic hydrocarbons (PAHs) have not yielded consistent results. Surfactant mobilization of high molecular weight (MV) PAHs from contaminated soils has not been extensively studied; therefore, t he purpose of this research was to compare the extent of release of freshly added high MW C-14-PAH with aged PAM from four different PAH-contaminated soils using a nonionic detergent, Tween 80, and to determine whether Tween 80-solubilized C-14-PAH in soil washings could be degraded by indigenous mi croorganisms or by added Penicillium spp. Only very high concentrations of Tween 80 (>1,000 times the critical micelle concentration [CMC] for 3 of 4 soils) were able to mobilize bound C-14-pyrene, -chrysene, and -benzo[a]pyr ene. The concentration of surfactant required to release 50% of bound C-14- PAH (the SC50 value) ranged from 5 to 30 gn depending on soil type; a modes t correlation was found (0.512) between the fraction of organic carbon in t he soil and the SC50 value. At 10(4) x CMC, Tween 80 released an average of 75% of bound C-14-PAH and 64% of the aged PAM, indicating that the C-14-PA H release only slightly overestimated PAM mobilization from weathered soil. An exception was one soil that had been previously remediated in which <30 % of the PAHs were released. The PAM structure had a negligible effect on t he mobilization by surfactant because the solubilization curves for all thr ee PAHs were very similar. Tween 80-solubilized C-14-pyrene readsorbed to s oil when the surfactant concentration dropped below 10(3) x CMC. Greater th an 90% of the C-14-pyrene in the soil washing effluent could be removed by the addition of spores of active PAM-oxidizing Penicillium spp. plus nutrie nts. In contrast, <10% of C-14-pyrene was oxidized by the indigenous soil b acteria under the same conditions.