NATURAL ATTENUATION IN BASALTIC RESIDUAL SOIL CONTAMINATED WITH BLENDS OF DIESEL AND BIODIESEL

Abstract

Biofuels (biodiesel) when used in mixtures with fossil fuels (diesel oil) become potential soil contaminants. The natural attenuation due to the low cost and little intervention in the natural conditions of the area is a competitive technique in soil decontamination. The aim of this study was to evaluate the degradation in laboratory of a residual soil from basalt contaminated with diesel and biodiesel mixtures. The soil was contaminated with a proportion of 4% relating to the mass of dry soil and compacted in the natural density of 1.6 g/cm³. The final soil moisture after contamination was 34%. It was used six different percentages of biodiesel called: B0, B5, B12.5, B20, B50, and B100. The mixture were molded in bioreactors in duplicate. Samples were collected after 105 days and they were analyzed by the Soxhlet extraction method and gas chromatography. The results showed that mixtures with higher percentage of biodiesel are more degradable. This shows that besides biodiesel being more biodegradable than diesel, it also assists in the degradation of fossil mixtures. To up to 12,5% of biodiesel in the mixture there was no significant difference in degradation. Keywords: Bioremediation, Soxhlet, Gas chromatography, Soil Contamination.