M Farahani - Faculty member of Islamic Azad University of Roudehen Branch
S.A Mirbagheri - Prof. Environmental Dept., Civil Engineering Department, K.N. Toosi University of technology

Poly aromatic hydrocarbons (PAHs) are hydrophobic organic compound found as major contaminants in soil Soil biological activities are vital for the restoration of soil contaminated with hydrocarbons. Successful application of bioremediation technology to contaminated soil requires knowledge of the characteristics of the site and the parameters that affect the microbial biodegradation of pollutants. This study was carried out to isolate high diversity of bacterial strain with the ability of degrading multiple PAHs and obtain the optimized conditions of biodegradation of these pollutants in laboratory. The diversity of indigenous bacteria in four soil contaminated samples from Tehran oil refinery able to degrade multiple PAHs were isolated and the physicochemical conditions of PAHs biodegradation were optimized by using the various concentration of the pollutants and changing pH, temperature and nutrients. The results showed that, the best conditions for efficient removal of PAHs are; pH 7.5, temperature 30 °C, and ratio of C: N: P 100:5:1, 100:10:1, and 100:5:1 for NH4No3, (NH4)2So4, (NH2)2Co as source of N, respectively. Finally, we carried out three treatments with a control to compare natural attenuation, biostimulation and bioaugmentation for PAHs degradation in soil. After 4 weeks of incubation, bioaugmentation of the contaminated soil showed the highest percentage of biodegradation of totalPAHs (70.5%).

Poly aromatic hydrocarbons, PAHs, Bioremediation, Contamination, Soil, Optimization