有机污染物在多孔介质中的残留

Residue of Organic Contaminant in Porous Media

土壤、地下水中的有机污染物主要以自由态、挥发态、溶解态和残留态等四种形态存在 ,其中残留态的部分是最难以去除的 ,残留量的多少是关系治理费用及治理时间长短的最关键因素。本文以柴油为代表 ,对地下水饱和区中有机物的残留进行了试验模拟 ,与非饱和区的残余饱和度进行了比较 ,揭示了饱和区中有机污染物残余的特点 ,并深入分析了其机理。结果表明 ,砂性介质中 ,地下水饱和区中有机污染物的残余饱和度显著大于非饱和区中的残余饱和度 ,因此可以有效地利用这一特性 ,通过降低地下水位使饱和区中部分残留态污染物转化为自由态 ,提高去除效率 ;与非饱和区中多孔介质粒径越小 ,残留量越大的特性相反 ,饱和区中测得的残余柴油饱和度随介质粒径的增大而增大。不同水位变动速度的试验结果表明 ,水位变动速度对粘性大于水的柴油的残余饱和度影响可以忽略不计。

Organic contaminants exist in soil and underground water in free liquid,dissolved,vaporized and residual status and the residual contaminant is the most difficult part to remove.Magnitude of residual saturation is the key factor to treatment cost and time.Diesel is selected as the representative of organic contaminants,and then residual situation of organic contaminants in subsurface saturated zone is investigated in this research by laboratory experiment.The result shows that,in sandy porous media,the residual saturation of organic contaminants in saturated zone is distinctively greater than the value in unsaturated zone,and this characteristic can be used to remove more contaminants effectively by lowering down groundwater level and making part of residual contaminants changed to free status.Contrary to the feature in unsaturated zone,where with the decrease of grain size,residual saturation in porous media will increase,experimental results in saturated zone show that residual saturation of diesel decreased with decreasing of glassbeads size.Different water table fluctuation velocity experiments show that the influence of water velocity on diesel residual saturation in saturated zone is negligible.