| Oil-contaminated soil can degrade soil quality,affect crop growth,pollute underground water sources and further harm human health.At present,common coupling remediation technology can make up for the deficiency of simple use of physical,chemical and biological remediation,but there are few studies on the degradation of residual pollutants in soil after microbial degradation.In this study,residual petroleum hydrocarbons in soil after microbial remediation are taken as the research object,and biological enhancement,biological stimulation and Fenton oxidation are adopted to study the law and mechanism of efficient degradation of residual pollutants in soil,with a view to realizing the efficient degradation of oil-contaminated soil by steps and providing certain references for the complete remediation of oil-contaminated soil.The main research contents and results are as follows:(1)Study on detection methods of petroleum hydrocarbon in soil.According to the detection status of petroleum hydrocarbon content in polluted soil,combined with the characteristics of petroleum hydrocarbon pollutants used in this study,the accuracy differences of infrared,ultraviolet and weight methods were compared and analyzed.It was concluded that ultraviolet method was more suitable for detecting low concentration petroleum hydrocarbon(<3.5wt.%)polluted soil.Gravimetric method is suitable for the detection of high concentration(>5wt.%)petroleum contaminated soil samples.The infrared method has strong applicability and is widely used in the detection of various concentrations of petroleum hydrocarbons,but its precision and reproducibility are relatively low.(2)Study on preparation of biodegradable soil contaminated by petroleum hydrocarbons.The composite bacteria M was prepared by using the preserved bacteria in the laboratory(Pseudomonas aeruginosa + Microbacillus oxide + Bacillus palpina intermediate = 1:1: 1)Degraded simulated petroleum-contaminated soil for 14 days to produce residual refractory petroleum-hydrocarbon contaminated soil samples with oil content of 1.5± 0.2wt %.GC-MS detection and analysis showed that the residual pollutants in the soil were mainly alkanes with14-27 carbon atoms.(3)Degradation of residual hydrocarbon pollutants in soil.By adding sterile water,degradation of conventional bacteria,degradation of newly degraded bacteria,Fenton+conventional bacteria degradation,Fenton+ newly degraded bacteria and other methods,the concentration change of remaining petroleum hydrocarbon in soil within 21 days was investigated.Soil oil content decreased from 13417.68mg/kg to 11434.28,9167.23,6891.05,6661.07 and 5679.17mg/kg,and degradation rates were 14.78%,31.68%,44.05%,50.36% and57.67%,respectively.Among them,Fenton+ new degrading bacteria is the best degradation scheme.The chromatographic analysis results show that the peak value of all linear alkanes decreases,and the content of all linear alkanes decreases obviously,and the linear alkanes of C14 disappear completely after degradation,indicating that Fenton oxidation technology has an obvious promoting effect on microbial degradation.(4)Feasibility study of coupling remediation technology applied to actual oily sludge.By using Fenton+ composite microbial remediation technology to degrade different concentrations of oily sludge,the oil concentration in 35 d soil decreased from 88400,57900 and 24600 mg/kg to 64100,26700 and 8200mg/kg,respectively.After the degradation of high concentration oily sludge,C13,C14 and C16 increased significantly,while C20 disappeared,while C23,C32 and C18 decreased significantly.During the degradation of medium concentration oily sludge,all the substances decreased,and C14,C23,C29 and C30 decreased significantly.In the low concentration of oily sludge,C14 increased significantly and C23 decreased significantly.The results showed that the coupled remediation technology could effectively reduce the pollution concentration of petroleum hydrocarbons in soil while fully shortening the degradation time. |
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