气相抽提法去除土壤中挥发性有机污染物现场试验研究

为研究气相抽提技术(SVE)现场去污效果及影响因素,在北京市某化工厂搬迁遗留场地,以苯系物为目标污染物,应用气相抽提法进行场地污染修复现场小试,考察了气相抽提真空度、气体抽排流量、空气渗透率及温度变化等的影响。试验结果表明,抽提真空度存在最优值(试验场地在30 k Pa左右),在该值附近,抽取的气体流量最大(流量为13.5 m3/h);抽出气体的污染物浓度及去污速率随流量增大而提高,在不考虑污染物由土壤中迁移过程的限制时,去污速率基本正比于抽气流量;土壤的透气性越强,气相抽提的影响半径越大,抽气流量以及去除污染物的速率也越高;抽出气体的污染物浓度及去除速率总体随温度的升高而增大。

Field Study on Influencing Factors in Removal of Volatile Organic Compounds by Soil Vapor Extraction

Soil vapor extraction (SVE) has been effectively used for the removal of volatile organic compounds (VOCs) from unsaturated soil in foreign countries. We have established a field site in a chemical plant in Beijing and carried out the remediation test of using SVE to remove the benzene. The effects of vacuum, vapor flow rate, soil air permeability and temperature on the SVE are studied. There is an optimal vacuum value at which the vapor flow rate is maximal. Both the pollutant concentration in the extracted vapor and decontamination rate of VOC increases with the increase of vapor flow rate and the latter linearly increases without considering the transport of VOC in the soil. The influence radius of SVE is larger and the vapor flow rate and decontamination rate are higher when the air permeability of soil is higher. The pollutant concentration in the extracted vapor and decontamination rate increases with the increase of temperature.