REMEDIATION OF OIL-CONTAMINATED SOILS WITH COMPOSITIONS BASED ON HUMIC ACIDS

In addition to conventional methods, nowadays new approaches and technologies based on combined application of sorbents and microorganisms are intensively developed for efficient control of oil contaminations. As a biotechnological solution for remediation of various oil-contaminated soils, biocompositions based on an organic matrix - humic acids of peat, and a biological component - a single strain/or an association of oil degrading microorganisms of the genera Rhodococcus and Pseudomonas, have been studied. The efficiency assessment of oil contamination biodegradation using biocompositions was carried out on different types of model oil-contaminated soils with different levels of contamination: grey forest soil, Black Sea pebbles (fraction 20-50mm), constructional broken stone (fraction 10-20mm). Natural soil contaminated with oil products and samples of railroad broken stone (fractions 5-30mm and 35-50mm) were also used. It has been shown that the biocompositions based on three strains of microorganisms - 'HA R. X5 R. S67 Ps. NF142' - possessed the highest capability of degrading oil hydrocarbons in all systems under study. Biodegradation of oil hydrocarbons upon addition of this biocompositions varied between 62 and 82% depending on the type of oil-contaminated soil, the level of contamination being very high. Monobacterial biocomposition 'HA Ps.NF142' has p roven to be promising for remediation of oilcontaminated soil ecosystems with a high and very high level of contamination. The increase of the level of biodegradation of oil contamination of soils appears to be due to the combined action of humic acids comprising both the stimulating effect of humic acids on microorganisms - the components of biocompositions and indigenous microflora of model systems, and the detoxifying effect of humic acids in respect of oil hydrocarbons.