Transformation of a petroleum pollutant during soil bioremediation experiments

The experiment of ex situ soil bioremediation was performed at the locality of the Oil Refinery in Pancevo (alluvial formation of the Danube River, Serbia) polluted with an oil type pollutant. The experiments of biostimulation, bioventilation and reinoculation of an autochthonous microbial consortium were performed during the six-month period (May-November 2006). The changes in the quantity and composition of the pollutant, or the bioremediation effect, were monitored by analysis of the samples of the polluted soil taken in time spans of two weeks. In this way, from the beginning until the end of the experiment, 12 samples were collected and marked as P1-P12 (Pancevo 1-Pancevo 12). The results obtained showed that more significant changes in the composition of the oil pollutant occurred only during the last phases of the experiment (P8-P12). The activity of microorganisms was reflected in the increase of the quantity of polar oil fractions, mainly fatty acid fractions. In this way, the quantity of total eluate increased, and the quantity of the insoluble residue was reduced to a minimum, whereby the oil pollutant was transformed to a form that could be removed more efficiently and more completely from the soil, as a segment of the environment.