2011 年 54 巻 3 号 p. 294-301
During the Persian Gulf War in 1991, an estimated 6 to 8 million barrels of crude oil were spilled, and a great portion of these pollutants was transported to Khuzestan's soils. Contaminated soil is a risk to the environment, and therefore, reclamation of polluted soil is vital. To address this problem, bioremediation methods were investigated. In this study, soil was artificially polluted with 1% crude oil, and sewage sludge was used at 2 levels equivalent to 50 and 100T/ha of field application. Soils were kept at 25-30℃ and 60% of field capacity for 5-10 weeks. The soils were then analyzed for the presence of hydrocarbon-degrading heterotrophic bacteria and chemical properties. Oil degradation was measured by the oil soxhlet extraction method and gas chromatography. Results showed that hydrocarbon-degrading heterotrophic bacteria increased from 6×103CFU/g soil to 2×1010CFU/g soil and the soil C/N ratio decreased from 6 to <3. In addition, sewage sludge treatment degraded the oil by 43-61%. Gas chromatography showed the reduction of all normal alkanes and isoprenoids, such as phytane and pristine. The present findings suggest that sewage sludge treatment of oil contaminated soil at 100T/ha over 5 weeks can cause optimal oil degradation and is therefore a suitable treatment for bioremediation.
