FATE OF PETROLEUM HYDROCARBONS ANDBENZENE UNDER BIODEGRADATION INCONTAMINATED SOILS

摘要

Microbial decontamination of petroleum-polluted soils has been recognized to be an efficient, economical and versatilernalternative for physical or chemical treatments. In this study, the fate of different components of petroleum in contaminated soil wasrninvestigated under optimal environmental conditions which were determined by previous experiments. An aerobic bacteria speciesrnwith the ability to utilize hydrocarbons and benzene as carbon and energy sources was identified as Flavobacterium sp. Based onrnmorphological, physiological and biochemical tests. It was isolated from the contaminated soil using selective enrichment culturerntechnique. The results demonstrate a 39.88% removal rate for total petroleum hydrocarbons over a period of 27 days. Differentrnfractions of the petroleum were observed to be degraded incongruently. The degradation rate declines with increasing alkane chainrnlength(carbon number). It was found that the total degradation rate can be approximated by the degradation rate of the n-alkane withrn23 carbon atoms. N-alkanes with carbon number lower than 23 were removed faster than the total hydrocarbon amount, and thernreverse trend was observed for n-alkanes with carbon number higher than 23. Unlike n-alkanes, the degradation rate of total isoalkanesrncan be simulated by that of with iso-alkanes with 19 carbon atoms. The benzene utilization studies with the bacteria speciesrnshowed that it metabolizes benzene when benzene concentration is under 10mg/L, concentrations over which turn out to be inhibitory.rnThe optimal conditions for effective removal of benzene by this species appeared to be 30 ℃, pH of 6.5-6.7, shaker speed of 150-220rnrpm, inoculum concentration of 10% (v/v).