In situ bioremediation potential of an oily sludge-degrading bacterial consortium

A field-scale study was conducted in a 4000 m(2) plot of land contaminated with an oily sludge by use of a carrier-based hydrocarbon-degrading bacteri al consortium for bioremediation. The land belonged to an oil refinery. Pri or to this study, a feasibility study was conducted to assess the capacity of the bacterial consortium to degrade oily sludge. The site selected for b ioremediation contained approximately 300 tons of oily sludge. The plot was divided into four blocks, based on the extent of contamination. Blocks A, B, and C were treated with the bacterial consortium, whereas Block D was ma intained as an untreated control. In Block A, at time zero, i.e., at the be ginning of the experiment, the soil contained as much as 99.2 g/kg of total petroleum hydrocarbon (TPH). The application of a bacterial consortium (1 kg carrier-based bacterial consortium/10 m(2) area) and nutrients degraded 90.2% of the TPH in 120 days, whereas in block D only 16.8% of the TPH was degraded. This study validates the large-scale use of a carrier-based bacte rial consortium and nutrients for the treatment of land contaminated with o ily sludge, a hazardous hydrocarbon waste generated by petroleum industry.