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 6×103 cfc/gr in
control soil to 2×1010 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.
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