Source-sink Mechanism And Remediation Technology Of Polycyclic Aromatic Hydrocarbons In Soil At Peri-urban Industrial Area

Affected by industrial activities, agricultural irrigation, atmospheric deposition and vehicle emission,soil pollution at Peri-urban industrial area is complicated, serious and harmful. Polycyclic aromatic hydrocarbons (PAHs) are a typical group of wide spread persistent organic contaminants in the environment. It is vital to ascertain the pollution pattern and source-sink mechanisms of organic contaminants and to develop effective remediation technology for ensuring the sustainability of land use and food safety. In this study, Banshan industrial area in Hangzhou was selected to study the pollution level,spatial and temporal distribution pattern and the source-sink mechanism of PAHs in peri-urban industrial area. New technology and facility were developed based on mixed surfactant enhanced soil washing, which were successfully applied in site remediation project. Some useful results were obtained in this study as below:(1) The pollution pattern and source-sink mechanism of PAHs in soils at Banshan industrial area were ascertained. The PAHs concentrations in soil ranged from 572 to 4654?g/kg with a significant decrease gradient from coking plant, power plant and oil refinery plant to the rim, which were increased during the investigation. The contribution of dry deposition, wet deposition and irrigation to PAHs concentration in agricultural soil were 54.8%, 25.5% and 19.8%, respectively. Source-sink mechanisms were analyzed based on the fugacity model, which revealed that soils in this area were switching from the sink to source of PAHs due to regional restructuring of energy and industry.(2) Remediation technology based on mixed surfactant enhanced soil washing were further developed. Anionic and nonionic mixed surfactant (SDS:Peregal=1:9) was the most effective washing detergent, and the process parameters, such as surfactant concentration, contact time, stirring method, were optimized, which can support the engineering application. Soil washing effluents treatment methods were developed based on the removal of organic contaminants by organobentonite/magnetic organobentonite,which can recover surfactant solution in washing effluent.(3) Integrated facilities based on mixed surfactant enhanced remediation and reuse of soil washing effluent were developed. Facilities contained the washing process and washing effluents treatment process, which have been successfully applied at remediation projects. Facilities can effectively remove organic contaminants in soil and recover the washing effluents simultaneously, which realized zero-emission of waste water.