Bioremediation of Soil Contaminated with n-Hexadecane in Slurry Phase and Investigation of Effective Parameters

Soils contaminated with organic pollutants are nowadays one of the important environmental issues. Bioremediation is a simple, economic method for decontamination of such soils. In this work, biodegradability of hexadecane in slurry phase by an isolated bacterium is investigated in order to reduce the carbon content of a polluted clay soil. A model system was used including Kaolin clay soil of mesh size 100 and n-hexadecane (equivalent to diesel fuel) as the model soil and pollutant, respectively. Polluted soil containing hexadecane as the only carbon source for the bacterium has been incubated in slurry phase for 20 days in shaking cultures (200 rpm and temperature of 30 oC). Hexadecane decomposition at various hexadecane concentrations (10000 and 30000 ppm), soil to water ratios (0.2 and 0.33) amounts of inoculum (5 and 10 %) and initial pH (5.5 and 7) has been investigated. Hexadecane decomposition has been assessed based on measurement of total organic carbon (TOC). 10-70 % reduction in TOC was observed under various conditions indicating the high capability of this bacterium in biodegradability of hexadecane in slurry phase. Since the presence of biosurfactants in media containing organic compounds can increase the solubility of such compounds, surface tension was also measured as a criterion for the presence of biosurfactants. Surface tensions of 29-60 mN.m-1 were measured at various conditions confirming biosurfactant production by this bacterium.