| Polycyclic aromatic hydrocarbons(PAHs)are a kind of soil organic pollutants with strong carcinogenic,teratogenic and mutagenic properties,which possess low steam pressure,high octanol/water partition coefficient as well as poor bioavailability characteristics.Ex-situ washing remediation technology is a remediation technique for contaminated soil,which has a wide practical application prospect and a lot of advantages such as high treatment efficiency,short treatment cycle and low treatment cost.In this paper,regarding the artificial soil pollution and actual contaminated soil as the research objects,we explored the washing removal effect as well as the influencing factor of the alcohol eluant and surfactant on the soil contaminated by phenanthrene and benzo[a]pyrene,in order to find out the best leaching condition.The mainly studying influencing factors include the variety and concentration of eluting reagent,the solid-liquid ratio,washing time,temperature,cycles and the concentration of the pollutants.Besides that,we also compared the washing effect between the artificial contaminated soil and the actual contaminated soil.The main conclusions are as follows:(1)Alcohol eluting agent had a good removal effect on washing out phenanthrene and benzo[a]pyrene from the artificial contaminated soil and actual contaminated soil.For the artificial contaminated soil,the washing removal rates of phenanthrene by propanol and ethanol eluent were 93.05%,93.57%,while the removal rates of benzo[a]pyrene were 86.85%,88.89%under the optimum conditions;for the actual contaminated soil,the washing removal rates of phenanthrene by propanol and ethanol eluent were 87.41%,84.02%,while the removal rates of benzo[a]pyrene were 71.67%,80.70%under the optimum conditions.Because with the time going,the actual contaminated soil were harder to be eluted than the artificial contaminated soil.We need to increase the alcohol concentration,washing time and temperature to get a good washing effect.(2)Surfactants have a good washing effect on washing out phenanthrene and benzo[a]pyrene from the artificial contaminated soil rather than the actual contaminated soil.For the artificial contaminated soil,the washing removal rates of phenanthrene by SDBS,Triton X-100,Tween 80 were 77.29%,75.02%,75.84%,while the removal rates of benzo[a]pyrene were 73.05%,71.07%,64.21%under the optimum conditions;for the actual contaminated soil,the washing removal rates of phenanthrene by SDBS and Tween 80 were 32.28%,34.20%,while the removal rates of benzo[a]pyrene were 71.67%,80.70%under the optimum conditions. |
