基于碳数分段法的石油烃污染土壤异位热脱附工艺的优化

针对石油烃污染土壤成分复杂、污染严重、修复难度高的问题，采用适用性广、效率高且去除彻底的异位热脱附技术修复石油烃污染土壤。利用碳数分段法及室内模拟实验，探究在热脱附过程中的土壤粒径、含水率和有机质对石油烃及各组分热解吸效率的影响；另外，还采用响应面法对各影响因素进行了优化，以获得异位热脱附修复石油烃污染土壤的最优工艺参数。结果表明，当污染土壤粒径高于1 mm时，石油烃脱附效率均可达90%以上，且粒径越大土壤颗粒中石油烃去除率越高。其中，润滑油段(ORO, C28~C40)组分的脱附效率随粒径变化最为明显。当土壤含水率为15%、脱附时间为50 min时，石油烃脱附效率最大为52.63%。另外，土壤中有机质含量越低，越利于石油烃的脱除，且高温(400~500 ℃)条件下可基本消除土壤中高含量有机质(3.82%)对石油烃脱除的阻碍作用。响应面优化实验得到的最佳工艺参数条件为，粒径2 mm、有机质含量1.44%、含水率为17.68%，在此条件下的石油烃脱附去除效率可达65.32%。该研究结果可为热脱附技术在石油烃污染场地的实际应用提供参考。

Optimization of ex-situ thermal desorption of petroleum hydrocarbon contaminated soil based on carbon number-based fraction approach

In view of the complex composition, serious pollution and high remediation difficulty of petroleum hydrocarbon contaminated soil, the widely applicable, highly efficient and complete removal of ex-situ thermal desorption (ESTD) technology was adopted to remediate petroleum hydrocarbon contaminated soil. The effects of soil particle size, moisture content and organic matter on the removal efficiency of petroleum hydrocarbons and their components during thermal desorption were investigated by using carbon number-based fraction method and laboratory simulation experiment. In addition, the response surface methodology was used to optimize the influencing factors to obtain the optimal process parameters for the remediation of petroleum hydrocarbon contaminated soil by ex-situ thermal desorption. The results showed that the removal efficiency was more than 90% when the soil particle size was higher than 1mm, and the larger the particle size was, the higher the petroleum hydrocarbons removal efficiency was. The removal efficiency of the ORO components (C28~C40) varied most obviously with soil particle size. The maximum petroleum hydrocarbons removal efficiency was 52.63% at a soil moisture content of 15% and 50 min of desorption. The lower the content of soil organic matter, the more favorable the removal of petroleum hydrocarbons, and the high temperature (400~500 ℃) can basically eliminate the hindering effect of high soil organic matter content (3.82%) on the removal of petroleum hydrocarbons. The optimal process parameters obtained from the response surface optimization experiment were: soil particle size of 2 mm, organic matter content of 1.44%, moisture content of 17.68%, and the removal efficiency of petroleum hydrocarbons under these condition reached 65.32%. The results of this study can provide a reference for the practical application of ESTD technology in petroleum hydrocarbons contaminated site.