Study On Microbial Remediation Of Saline-alkali Soil Polluted By Petroleum

At the same time when petroleum brings great economic benefits, it poses serious threat to the environment. During the process of reconnaissance, exploitation, transportation and deposit, a large area around the oil field suffered from serious pollution. Microbial remediation technique attracts people's attention due to its economy, high efficiency and no second contamination.According to the actual state of oil polluted soil in Dongying area and main problems in microbial remediation of oil polluted soil, 288 strains and 22 kinds of mixed strains oil degrading microorganisms were isolated from the oil polluted soil. After secondary screening, two strains and one kind of mixed strains exhibited better biodegrading ability.Many factors govern the process of degrading. Every factor's influences on both strain 32-13 and mixed 13 were analyzed. When the pH was 7.5 and the inoculum size was 4%, strain 32-13's deoil efficiency was high. When the pH was 8.5 and the inoculum size was 2%, mixed 13's deoil efficiency was high. Both of them exhibited better biodegrading ability when the oil concentration was 30g·L-1, besides, the deoil efficiency became higher with increasing shaking bed time. According to the Manual of Determinative Bacteriology( tenth edition), the results of primary identification showed that strain h13-1, strain h13-2, strain h13-6 and strain 32-13 were Bacillus, strain h13-3 Pseudomonas, strain h13-4 Micrococcus, strain h13-5 Neisseria. Because mixed 13's deoiling ability was strong and steady, it would be used in next reparative experiment.Collect oil polluted soil in Dongying area. After investigating some of its physical and chemical properties, it was used in reparative experiment. Whether the exogenous microbes mixed 13 accelerate the rate of the bioremediation or not is studied and the impact factors on the biodegradation of the petroleum contaminated soil were investigated too.The total petroleum hydrocarbon of the soil was monitored during the treatment and the influence factors such as the concentration of nutritional salts, bulk agent( wheat branusp), the varied initial inoculum sizes of the soil were investigated. The experiment was lasted for 180 d. When the water content of the soil is given, the exogenous microorganism can speed up the biodegradation of the petroleum greatly. When mixed 13's inoculum size was 10%, it exhibited better repairing effects. There was an optimum match between microorganisms'growth and the concentration of nutritional salts. The optimum concentration of N was 0.35mg·kg-1and the optimum concentration of P was 0.7mg·kg-1.In the experiment, as the amount of wheat branusp increased, the degradation rate increased. When the wheat branusp volume was 25% of the soil, the biggest degradation rate was 56.8% after 180d.