The enhanced bioremediation of soils contaminated with high concentration of diesel oil

A selected strains of Trichoderma sp. Aspergillus niger, yeasts and bacterial cocktail, isolated from hydrocarbon contaminated soil have been investigated for diesel oil biodegradation in highly polluted soil. To assess the ability of microorganisms to degradation, two sets of experiments were conducted, that is column test (6 months at 0 to 150 degrees C) and microcosms (7 weeks at 25 degrees C). Total hydrocarbons (TH), total organic carbons (TOC), dehydrogenase activity (DHA), pH and humidity were monitored. The process biodegradation of oil diesel was depend on temperature, concentration of contaminant and used microorganisms. At the lower temperature and diesel concentration from 5 to 10% more effectively were fungi, but at higher diesel concentration - bacteria. During column experiment the best hydrocarbon removal efficiency (HRE) were obtained in the case of addition of bacterial cocktail and 50% of soil contamination - 50.65%. At the higher temperature (microcosms experiment) the highest HRE showed Aspergillus niger (48%) and bacterial cocktail (52.7%), respectively. The greater microbial activity (dehydrogenase activity) was observed at higher temperature with bioaugmentation of soil with fungi and upon natural attenuation of the sample. The addition of glucose caused significant increase of DHA values. TOC values increased within time in both type of experiments.