Study On Properties And Petroleum Component Change Of Microbial Remediation In Oil Contaminated Soil

The development of many countries' economy relied on production and use of the crude oil because of its wide range of use and the mature mining and refining technology.However,it brought a lot of problems when the crude oil was explored and consumed largely.The problem that the soil was contaminated by the oil was taken seriously by people increasingly.The method that the microorganism was used for repairing the contaminated soil by oil not only restored the soil environment,but also recycled the polluted land,which brought economic,social and ecological benefits.Our research was carried out through a simulated repair experiment.We followed the tracks of the physical and chemical properties,the contents of the oil hydrocarbons and the component change of the soils.Moreover,we explored not only the changing characteristics of the soil p H,organic matter,total nitrogen content and so on,but also the change and composition characteristics of the component contents.The results were showed as follow:The different experimental condition parameters affected the extraction efficiencies of the oil hydrocarbons in soils differently and the extractant was the most important element.We used 20 mL dichloromethane,which was extracted by ultrasonic extraction in 10 min,then in a centrifugal velocity of 4000 r/min in10 min and 4 times at last,in order to obtain the maximum extraction rate.Under these conditions,the extraction rates of the oil hydrocarbons in soils were ranged 99.07% to 100.95%.After the soils were contaminated by oil,the content of organic matter was increased significantly,the contents of pH,total nitrogen and alkali IVristine IVble nitrogen were relatively stable,and the contents of total phosphate,available phosphate and available potassium were decreased.After adding the conditioner,the contents of soil p H,total nitrogen,available nitrogen,total phosphate,available phosphate and available potassium were changed significantly.The conditioner improved the soil fertility,provided adequate nutrition for microbial growth and metabolism,and laid the foundation for microbial degradation of soil hydrocarbons.In the repair process,the contents of the oil hydrocarbons in soils changed differently in different test groups.They were all decreased in our 10 test groups,which were showed that the oil hydrocarbons could be degraded or volatile s ubstance when they entered the soils in the natural environment and the change of external conditions had a significant effect on the microbial degradation of the oil hydrocarbons.The relative contents of different groups in the oil hydrocarbons changed under the effect of microorganisms.Especially in the experimental group added conditioner,the contents of the aliphatic hydrocarbons were decreased significantly,the percentages of the aromatic hydrocarbons had no significant change,and the percentages o f the non-hydrocarbons were enhanced significantly.The change of the percentages of the Pr/nC17,Ph/C18,Pr/Ph,steranes terpanes in each test group showed that the different composition of the saturated hydrocarbons were used by microorganisms in differe nt utilization degree.The microorganism utilized the straight-chains at advance,then utilized the alkanes,at last utilized the steroidal terpenes which were stable in soils due to their anti biodegradation ability.The naphthalene and phenanthrene in the aromatic hydrocarbons changed significantly.There were significant effects on the degradation of the naphthalene series compounds and phenanthrene in the conditioner group and they were not detected in the late repair process.And they were decreased in the non-conditioner group with varing degrees.In addition,the methylation of two benzothiophene was detected in the repair process.We suspected that the two benzothiophene could exist the synthesis reaction and the degradation reaction at the same time.And the two methyl benzo [a] anthracene,methyl fluorine which was detected by us could exist the demethylation reaction.Finally,the conditioning agent not only can promotes the properties of the soil,but also promotes the effect of microorganisms on the the removal of the oil hydrocarbons in soils.