Abstract:In order to provide sufficient basis for treatment of petroleum contaminated soil, the optimum physical and chemical conditions of soil were explored for petroleum hydrocarbon degradation by immobilized microorganisms. The optimal carrier immobilized microorganism was selected from several agricultural wastes to degrade crude oil of Qianguo oil field. Effects of quantities of immobilized microbial, initial concentration of crude oil, dosage of surfactant, porosity, moisture content, pH value, and nutrient content on degradation rate of oil were examined. The results show that straw is the best carrier of immobilized microorganism, and the optimum degradation conditions include immobilized microorganism of 50 g/L, porosity of 45%, moisture content of 20%, pH value of 8, and C/N=8. The ability of immobilized microorganisms to degrade petroleum-polluted soil is far greater than that of free bacteria, and degradation efficiency of petroleum-polluted soil can be greatly improved by adjusting to the optimal soil environment and appropriate using of surfactants and immobilized microorganisms.