| Since 1980', studies on the biodegradation of petroleum-polluting soil by microorganisms have been hotspots. Some success has been achieved for these 30 years.In this paper, 7 strains of petroleum-degrading microorganisms were screened. 6of them were bacteria--X-5, X-12, X-13, X-21, X-22 and X-23 and the other onewas fungi--Z-26. From the degradation characteristic study of the 7 strains, it wasknown that X-12 and X-13 could secrete biosurfactant to emulsify the oil. While X-21, X-22 and X-23'cell membranes had good hydrophobicity so that they could stick to the oil drops very well. In addition, they also had the ability to disperse the petroleum. X-5 and Z-26 had no capacity of dispersion. They could just adsorb the oil by sticking to the oily layer. X-12, which could endure more than 3%'s oil concentration, had a good tolerant capacity. And Z-26 was very sensitive to the petrolic toxicity. The others' highest degrading rates were obtained when the oil concentration was 2%. The analysis of mixed microorganism consortium research implied that X-12 had a strong bacteriostasis to the other strains. However, there was no obvious inhibition among X-5, X-23 and Z-26.The oil-biodegrading rates were above 40% in both soil sample 1 and soil sample 2 in composting experiment where X-12 was dominant strain. Saturated hydrocarbon was degraded much faster then aromatics, colloid and asphaltene. It was the hydrocarbons whose molecular weights were lower than 26-alkane that could be degraded much faster by microorganisms. The composting influence to the heavy metal pollution of the soil was slight and different basing on the heavy metals.The treatment method that degraded oil with mixed microorganism consortium and white rot fungi in order was good for removing the pollutant. The gas chromatography test indicated that n-alkanes could be removed absolutely whose molecular weights were higher than 18-alkane. |
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