Bioremediation of crude oil polluted soil as affected by sewage-sludge

During the Persian Gulf war in 1991 around eight million barrels of crude oil were spilled into water. This caused a large volume of contaminated water has to move to land in particular, Khuzestan's soil. A real danger of oil pollution would be an environmental calamity, and therefore, reclamation practice on the spoil soil area to expel the oil is essential. Bioremediation methods will be surveyed. In this study the soil artificially polluted with 1% density of crude oil and sewage sludge were applied at 3 levels of 0, 50 and 100 ton/h equivalent to the field application. These soils were kept at 30°C and 60 percent of F.C. for 5 to 10 weeks. The soils were then analyzed for hydrocarbon-degrading, heterophic bacteria count and some other soil chemical properties. Oil degradation was measured by a Soxhlet extraction method, and gas chromatography. Data indicated that treatments caused the degradation of 45% to 60% of oil in contaminated soil. The results showed that the degrading heterotrophic bacteria population increased from 6×10 cfc/gr in control soil to 2×10 cfc/gr in treated soil and C/N ratio decreased from 6 to less than 3. Gas chromatography results also showed a decrease in normal paraffin and isopernoids, like phytane and pristine.