土壤气相抽提技术去污规律及土层压力变化特征分析

摘要

土壤气相抽提(SVE)技术可有效去除包气带土壤中挥发性有机污染物(VOCs),是一种经济高效的土壤原位修复技术.对北京市某化工厂内进行SVE技术的现场应用,去除污染土壤中的VOCs,研究污染物的消减规律以及土层压力的变化特征.结果表明,抽出气体的污染物浓度随SVE的运行不断降低,群井抽气初期,VOCs浓度迅速下降,之后进入长时间的拖尾阶段,VOCs浓度相对较低且下降缓慢.土层气相真空度随距抽气井距离的增大逐渐降低,真空度与距离基本呈对数相关.抽气井附近的真空度梯度及气相流速最大.群井抽气时,土层气相真空度分布受抽气井布设位置及布设形状影响,土壤气相压力降漏斗长轴方向与抽气群井布置方向一致.%Soil vapor extraction (SVE) system can remove the volatile organic compounds in the non-saturated soil effectively; it is a cost-effective in situ remediation technology. The SVE system was applied in a chemical plant in Beijing,and the reduction laws of pollution and the variation of soil pressure were analyzed in this paper. As the system running,the concentration of gas pollutants continually lowered. The concentration of VOCs was decreased significantly in the initial stage, and then it entered to trailing phase, in which the VOCs was relatively low and declined slowly. The vacuum of soil was decreased with increasing the distance from extraction well. The vacuum and gas flow rate was the maximum near the extraction well. Distribution of soil vapor vacuum laid by the well location and distribution shape,cone of depression located at the pumping well group.