Biodegradation of Photoirradiated Polycyclic Aromatic Hydrocarbon Constituents of Creosote Oil

Abstract

The influence of the photochemical pretreatment on the biodegradation of naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, and pyrene were studied. In aqueous media these PAHs were photoreactive. Aerobic PAH degrading bacteria were enriched on creosote or on a mixture of the six PAHs. The pre-irradiation enhanced mainly the onset of the biodegradation, particularly PAHs treated as the components of creosote. The biodegradation rate of irradiated acenaphthene in creosote on the second day was 50% better than that in the non-irradiated sample. The biodegradation rates of anthracene irradiated individually and in creosote were 35% and 58% higher, respectively, than those of the non-irradiated samples on the second day. On the seventh day there was a 70% difference between the biodegradation rates of irradiated and non-irradiated pyrene treated in creosote in favor of the irradiated sample. The biodegradation of non-irradiated fluorene ceased in two days while the degradation of irradiated fluorene was almost complete in seven days. Photochemical treatment produced several intermediates as detected by a gas chromatograph with a mass spectrometer (GC-MS). The intermediates were more biodegradable than the parent compounds.