Abstract

Bioaugmentation is one of the best option treatment technologies in which hydrocarbon-degrading bacteria are added to contaminated soil to accelerate the degradation capacity at the site. In this study, three hydrocarbon-degrading strains were used to examine the efficiency of single strain and mixed cultures for remediation of oil sludge contaminated soil. Five different sets of treatment containing 10 kg of soil with 10% oil sludge were prepared as: Treatment A, Treatment B, Treatment C, Treatment D, and Treatment E [contaminated soil without bacterial inoculation ]. The reduction of TPH in each bioreactor was observed during 60 days treatment periods. The physiochemical parameters such as pH, temperature, moisture content, and biological population in soil were investigated during the bioremediation process. The results obtained revealed bioaugmentation using mixed cultures was proven to be better approach to treat oil sludge with 88.2% degradation of TPH followed by Treatment C > Treatment B > Treatment A > Treatment E with 81.6%, 80.7%, 80%, and 57%, respectively. Hence, the results demonstrated that Treatment D with mixed culture was the most advantageous option for treatment of oil sludge as compared to single and natural attenuation treatment. This finding also demonstrated that all treatments except natural attenuation were able to degrade oil sludge up to 80% after 60 days of incubation period.