In situ bioremediation of a soil contaminated by mineral oil: A case study

Laboratory tests were conducted to study the feasibility of a bioremediation treatment. The first phase of the work was exploratory and comprised slurry condition microcosm tests. The second phase consisted of solid-phase microcosm tests to evaluate the effectiveness of the treatment and to estimate the time needed to reach the target level of 100 mg.kg fixed by the local environmental agency. The third phase consisted of helping the remediation company to select the appropriate technology, of choosing the strategy for its application in the field and of monitoring the site during treatment. From the microcosm tests data, the depletion rate became slower as a residual concentration of pollutants of ~ 500 mg/kg was reached. This residual contamination part was hardly bioavailable to the microorganisms that proved to be very active in using hydrocarbons as a carbon source. The results of the tests showed very low contaminant depletion rates. All the attempts to increase the bioremediation rate failed.