Study On H₂O₂-microbial Remediation Of Oil-contaminated Soil In JL Oilfield

With the development of China's industry and economy,the problem of environmental pollution has become increasingly serious.90%of the pollutants in soil are produced in the process of exploration,exploitation,processing,storage and transportation of petroleum,and petroleum pollution affects the original physical and chemical properties of the soil,threatens the survival of agricultural crops,and seriously endangers human health.We must seek a more effective and economical way to repair oil-contaminated soil to solve this urgent problem.Microbial remediation of oil-contaminated soils is more simple,high efficiency,low cost,and less secondary pollution than traditional methods.Therefore,it has attracted the attention of many domestic and foreign experts and scholars.In order to deal with the current serious oil-contaminated soil problem,this experiment takes the oil-soiled soil in the actual oil field as the experimental material.A petroleum hydrocarbon degrading bacterium capable of producing surfactants was selected from oil-contaminated soils,which were applied to microbial remediation of contaminated soils,and the optimal condition groups affecting the growth of microorganisms were filtered out.Finally,the joint treatment of chemical oxidation by H2O2 and microorganisms was used to treat heavy petroleum-contaminated soils.The main contents and results of this study are as follows:We identified the petroleum hydrocarbon degrading bacterium which was screened from contaminated soil in Jilin Oilfield named X2-2 through 16S rRNA,and the strain was determined to be Bacillus falciparum.The optimal growth conditions for producing surfactant X2-2 were:culture at 37?,concentration of NaCl was 2%,pH=7,inoculum amount was 4%,NH4NO3 as nitrogen source,carbon source was soluble starch,and carbon source amount was 4%.The metabolites of X2-2 were initially characterized as polypeptides,which have a good degradation effect on petroleum hydrocarbons.The results of microbial remediation experiments show that the addition of nutrients and modifiers cannot effectively degrade TPH.However,the addition of enriched native microorganisms and strain X2-2 can better promote the growth and reproduction of the bacterial and petroleum hydrocarbon degrading bacteria in oil-contaminated soils.The change of the number of petroleum hydrocarbon degrading bacteria is basically consistent with the change of TPH removal effect:when the growth of petroleum hydrocarbon degrading bacteria is in logarithmic phase,the TPH degradation rate shows a clear upward trend;when the petroleum hydrocarbon degrading bacteria is in the decline stage,TPH degradation rate basically no longer changes.Among different microbial remediation conditions,PCS+M+N+BA is most conducive to the growth of bacteria,with the largest number of bacteria,the largest number of petroleum hydrocarbon degrading bacteria and the best TPH degradation efficiency.After repairring,the TPH content was 1.33%and the degradation rate reached 63.71%.With the progress of oil-contaminated soil remediation,the distributive ratio of exchangeable Zn gradually decreased,and the distribution ratio of reducible Zn and residual Zn gradually increased.Among them,the exchangeable state of PCS+M+N+BA has a significant reduction effect.In this paper,the results showed that the most direct effect on the degradation of petroleum hydrocarbons in petroleum-contaminated soils was mix in 20%H2O2.The results of chemical-microbial combined repair experiments showed that the total number of bacteria reached the maximum on the 20th day when the microorganisms were used as pretreated soil samples,and the total number of bacteria reached the maximum on the 10th day of the experiment as a result of chemical oxidation as a pretreated soil sample.The effect of HPCS+M+N+CR is the best.The content of TPH was 5.28%and the degradation rate was 42.53%.Microbial remediation of hydrocarbons is characterized by short-chain hydrocarbons that are superior to long-chain hydrocarbons.Normal hydrocarbons are better than branched alkanes.However,the effect of hydrocarbon degradation on complex structures is not obvious.Alkanes with a carbon chain length of C22 or more are hardly degradable and insoluble in water.Chemical oxidation can act directly on slightly complex carbon chain structures.After the microbial remediation,the remaining complex alkanes that are difficult to be degraded can be directly oxidized by the oxidant.Microbial remediation as a pretreated soil sample is more conducive to the repair of petroleum contaminated soil than chemical oxidation as a pretreated soil sample.