EVALUATION OF BIOREMEDIATION EFFICIENCY IN CRUDE-OIL CONTAMINATED SOILS

During oil exploration the contamination of soils with petroleum hydrocarbons (PH) could take place. This is still today one of the major environmental issues. On the other hand, it is already known that bioremediation is cheaper and more efficient than others soil remediation techniques. Consequently, in the framework of the present research, the effect of bioremediation treatment applied to an artificially crude oil-polluted soil was assessed by the decreasing in the PH concentration analysed at different times. The paper presents results regarding the assessment of ex situ bioremediation method applied within an experiment conducted for the decontamination of a soil artificially polluted with crude oil, on an impervious platform. Besides the bioremediation efficiency in PH removing from contaminated soil, also soil quality parameters were monitored: pH, total organic carbon content, total nitrogen, C / N ratio, mobile phosphorus and potassium contents and the soil loading degree with inorganic pollutants, heavy metals. The initial concentration of PH in soil was 15.000 mg/kg The diversity of bacterial genera and species of the native soil was relatively high; 7 taxons were representative, belonging to Pseudomonas, Arthrobacter and Flovobacterium genera that are known for species with high abilities in petroleum hydrocarbons biodegradation. The experiments lasted for ten months and the removing efficiency was evaluated after three, five and respectively, ten months. Across the experimental study, the highest efficiency in PH removing from the crude oil contaminated soil was found in the range of months 3 and 5 since the experiment has started (almost 72%). The petroleum hydrocarbons biodegradation final efficiency was about 92%. The obtained results are demonstrating the potential efficiency of biological remediation method as an environmental friendly solution for a proper management of the crude-oil contaminated sites.