Biodegradation of diesel oil in soil by a microbial consortium

Biodegradation of diesel oil was performed using a diesel oil-degrading bacterial consortium, in both laboratory and pilot scale experiments. The bacterial consortium was prepared in liquid for laboratory tests and for pilot scale experiments, it was prepared in two steps, liquid and then in soil. The concentration of diesel in soil treated with the bacterial consortium was reduced to < 15% of the initial concentration, within a period of five weeks in both laboratory (135 to 19.32 g diesel kg (soil dry weight)^-1) and pilot scale (118 to 17.5 g diesel kg (soil dry weight)^-1) experiments, in comparison with controls (without bacterial consortium), in which initial concentration of diesel was reduced by only 5 and 15%, respectively. Diesel biodegradation rate with the bacterial consortium was 2.13 g diesel kg (soil dry weight)^-1 d^-1, it was slightly enhanced by the addition of NH₄NO₃ in the presence of bacterial consortium 2.78 g diesel kg (soil dry weight)^-1 d^-1. The enhancement of the microbial activity in hydrocarbon-contaminated soil can be achieved with the combination of stepwise soil inoculation and nutrient additions.