Transformation of oil and hexadecane in soil by microbial preparations and earthworms

Abstract

This study focuses on the effect of earthworms, oil-decomposing microbial preparation Destroil, and their combination on the destruction of oil in contaminated soil. The earthworms Eisenia andrei Bouché, 1972 accelerated the transformation of oil and hexadecane by microbiological preparations Destroil and Devouroil. The use of the combination of biological product and earthworms resulted in: (1) maximum reduction in the content of oil and hexadecane in the soil samples under study; (2) reduction of the phytotoxicity of oil-contaminated soil; (3) improvement in the agrophysical properties of soils in comparison with the action of these biodegradants separately. The transformation of oil hydrocarbons was monitored using NMR and IR spectroscopy. The biological oxidation process was accompanied by the accumulation of unsaturated triglycerides of variable structure. The chain length of the acid residue of triglycerides varied within the C11-C22 carbon atoms. In this case, the number of carbon atoms in the chain was most often -C18. The position of the double bonds was stochastic. At the same time, they were all removed from the carboxyl group by more than 4 carbon atoms. Stimulation of the processes of complex biotransformation of hexadecane under the action of the drug Devouroil and earthworms was manifested with the introduction of a biological product at concentrations of 32 × 1010 cells/kg and 64 × 1010 cells/kg. A further increase in the number of cells of the biological product Devouroil with the combined use of the biological product and worms led to a leveling of the stimulating effect of earthworms on the transformation processes of this hydrocarbon. At the same time, the phytotoxicity of the studied samples decreased.