Combined ozonation and biodegradation for remediationof mixtures of polycyclic aromatic hydrocarbons in soil

A study was conducted to investigate the feasibilityof a combined treatment (i.e., ozonation andbiodegradation) to overcome the inherent bacterialbioavailability limitation, and hence bioremediationlimitation, of polycyclic aromatic hydrocarbons insoil. Ozonation was very efficient in the removal ofnaphthalene, fluorene, phenanthrene, and anthracene,but not for pyrene, chrysene, and benzo(a)pyrene fromsoil freshly spiked with the hydrocarbons. A similarresult was obtained from coal tar-contaminated soil.Elimination of polycyclic aromatic hydrocarbonsincreased appreciably in sand containing 0.03%organic carbon, indicating the adverse effect oforganic carbon on the efficiency of ozone treatment.In spiked and coal tar-contaminated soils, ozonationfollowed by biodegradation significantly increased thedegradation of various polycyclic aromatichydrocarbons including chrysene and benzo(a)pyrenewhich were not degraded by the test bacterialconsortium alone. In particular, the effect of thecombined treatment was more pronounced in coaltar-contaminated soil than in sterile soil spiked withhydrocarbons, probably due to the augmented biologicalactivity of the introduced consortium. The resultssuggest that a combined treatment including ozonationand biodegradation may be a promising bioremediationtechnology in soil contaminated with mixtures ofpolycyclic aromatic hydrocarbons such as formermanufactured gas plant sites.