循环井水力激发下多相污染物的迁移转化规律

Migration and transformation of multiphase contaminant under hydraulicexcitation by circulation well

利用二维砂箱模拟实验,以苯、氯苯、苯胺和苯酚4种溶解性和挥发性不同的有机污染物为研究对象,分析循环井运行过程中溶解相、吸附相、挥发相的浓度变化,探究循环井水力激发下多相污染物的迁移转化规律。结果表明,循环井的水力激发直接作用于溶解相且污染物浓度呈指数衰减的规律,运行96 h后溶解相苯、氯苯、苯胺和苯酚的去除率为93.8%、89.9%、99.8%和95.0%。而吸附相和挥发相的污染物在浓度梯度的作用下迁移转化进入溶解相,再通过循环井的水力激发作用被去除。其中吸附相的迁移转化与污染物的溶解性有关,修复后苯、氯苯、苯胺、苯酚吸附相占比相对初始含量分别降低了56.1%、71.2%、21.1%、76.4%。而挥发相的迁移转化与污染物的挥发性有关,修复后氯苯和苯去除率为16.1%和15.7%。对比可知循环井的水力激发作用对溶解相的污染物具有最好的去除效果,其次是吸附相,挥发相最差。本研究成果可为循环井的场地修复设计提供参考。

Benzene,chlorobenzene,aniline and phenol with different soluble and volatile properties were taken as the target contaminant in a two-dimensional sandbox simulation experiment to analyze the concentration variations of dissolved phase,adsorbed phase and volatile phase during the operation of circulation well,and explore the migration and transformation rule of multiphase contaminants under the hydraulic excitation of circulation well.The results showed that the hydraulic excitation of the circulation well acted directly on the dissolved phase and the contaminant concentration decreased exponentially.After 96 h operation,the removal rates of dissolved benzene,chlorobenzene,aniline and phenol were 93.8%,89.9%,99.8%and 95.0%,respectively.The adsorbed phase and volatile phase contaminants are transferred and transformed into dissolved phase under the action of concentration gradient,and then removed by the hydraulic excitation of circulation well.The migration and transformation of adsorbed phase was related to the solubility of contaminants,and the adsorbed phase proportion of benzene,chlorobenzene,aniline and phenol decreased by 56.1%,71.2%,21.1%and 76.4%compared with the initial content,respectively.The migration and transformation of volatile phase was related to the volatility of contaminants and the removal rates of volatile chlorobenzene and benzene were only 16.1%and 15.7%.The comparison results showed that the hydraulic excitation of circulation well has the best removal effect on dissolved phase,followed by adsorbed phase,and the worst removal effect on volatile phase.This study can provide reference for site remediation design of circulation well.