Investigation Of Organic Pollution In A Polluted Site In Qingdao And Screening Of Remediation Technology

In this study,a particular construction project which located in Qingdao is taken as the research object.Through the investigation of the surrounding environment and soil samples of the field to identify the pollutant types and sources,and analyze the distribution law of Polycyclic aromatic hydrocarbons.Besides,this article takes the Benzo[a]pyrene which is the strongest carcinogenicity as the example to carry out the laboratory experiments.In the process of this experiment,analyzes the content characteristics of Benzo[a]pyrene and studied the factors that affecting the degradation of Benzo[a]pyrene by changing different physical and chemical properties and temperature conditions of soil.According to the characteristics of contaminated site and projects’requires,the remediation technology which is most applicable inorganic contaminated soil from polluted site can be screened out.In terms of the literature and the actual situation,the restoration schemes suitable for the contaminated site were screened in preliminary,the evaluation indexes are defined,the selection and evaluation system of the contaminated site is constructed,and the advantages and disadvantages of each restoration scheme are ranked by the analytic hierarchy process and the approximate ideal solution so that to determine the most suitable restoration technologies for the research site.The main findings are as follows:The type of PAHs pollutants in the contaminated site are Benzo[a]pyrene,Benzo[a]anthracene,Benzo[b]fluoranthene,Indeno[1,2,3-cd]pyrene and Dibenzo[a,h]anth-racene respectively.The main source of pollution is combustion.The contents of Benzo[a]pyrene,Benzo[a]anthracene and Benzo[b]fluoranthene are significantly higher than that of Indeno[1,2,3-cd]pyrene and Dibenzo[a,h]anthracene.The distribution of site pollutants is related to the process layout of coking plant.The distribution of pollutants in the vertical direction shows the law that as the increase of soil depth,the ability of pollutants to migrate downward decreases.By analyzing the content characteristics of Benzo[a]pyrene in four soils with different particle sizes,it was shown that the content of Benzo[a]pyrene in the soil with<0.075mm,particle size is the highest,followed by the 0.075-0.2mm and 0.5-2mm.The correlation coefficient of organic matter content and Benzo[a]pyrene content in soil is 0.949,showing an extremely significant positive correlation.The content of Benzo[a]pyrene in alkaline soil is higher than that in acid soil.The content of Benzo[a]pyrene in soil with high water content is also high,and the correlation coefficient between water content and Benzo[a]pyrene content is 0.995,showing an extremely significant positive correlation.The higher the ambient temperature,the lower the residual Benzo[a]pyrene content and the higher the degradation rate of Benzo[a]pyrene.The site restoration program which based on the technologies of in-situ heterotopic thermal desorption,cement cellar collaborative disposal and chemical oxidation are selected preliminarily.Four indicators that including the technical indicators,economic indicators,environmental indicators and social indicators are determined as evaluation indicators,and the weight ranking of a total of 10 subordinate indicators of the four indicators are conducted.After the comprehensive evaluation index of three kinds of restoration techniques are calculated and sorted by using the evaluation table of restoration techniques,it shows that the rank is as following:in-situ heterotopic thermal desorption technology,cement cellar collaborative treatment technology,and chemical oxidation technology.Thus the in-situ ectopic thermal desorption technology is determined to be the optimal scheme finally.