Extent of cleaning achievable by bioremediation of soil contaminated with petrochemical sludges

Abstract

Bioremediation is capable of reducing the hydrocarbon concentration of contaminated soil by 75-95% depending on the soil type, the kind of hydrocarbons and the history of the contamination. The impact of different number of petrochemical sludge applications to soil on the degree of PAH elimination was assessed. A simple and reliable extraction and gas chromatographic method was used to facilitate more rapid determination of hydrocarbon contamination in soils and sludge wastes. Its application in a model laboratory bioremediation experiment and a pilot field study were used to illustrate its practical benefits. Post-remediation persistence of sludge constituents was evaluated after a single dose sludge application in the laboratory and after seven sludge applications in the field. A relative increase in the concentration of some PAHs was detected at the end of the experiments, but their individual concentrations were reduced to suggested values for industrial soils. The remaining concentration of total hydrocarbons in soil was found to be similar in both experiments, pointing to soil organic matter adsorption capacity as the factor determining hydrocarbon elimination limits in soil bioremediation.