寒区石油污染场地浅层地下水原位增温强化空气扰动修复

Thermal enhanced air sparging for oil contamination remediation in shallow groundwater of cold regions

原位空气扰动技术(air sparging,AS)常被用在治理地下水与土壤的有机污染,在寒区,由于低温环境,污染物传质过程的多种基本参数受到影响,导致修复结果不理想。本文基于野外原位空气扰动实验结果,以甲苯为代表性污染物,进行室内土柱模拟实验,并构建增温空气扰动下污染物迁移模型,对野外场地增温强化空气扰动效果进行模拟,以预测采用增温方式时寒区污染物的去除效果。结果表明,甲苯的挥发速率与温度之间存在正比例关系;在室内柱实验中,高温注气条件下甲苯浓度衰减速率更快;野外数值模拟中的增温强化空气扰动修复过程中温度传导半径为2~4 m,曝气场污染物去除半径达10 m,比非增温强化条件污染物去除范围扩大3~5 m,进而将去除率有效提高40%~50%。

Air sparging(AS)is often used to treat organic pollution in groundwater and soil,while the remediation efficiency would be restricted by complex field conditions such as low temperature in cold regions.Based on the results of AS pilot test in the field,taking toluene as a representative pollutant,the remediation effect of thermal enhanced air sparging for the field scale was predicted and evaluated by indoor soil column experiment and numerical modelling.The results show that there is a direct proportional relationship between the volatilization rate of toluene and temperature.In the soil column experiments,the toluene concentration decay faster under the condition of AS with high temperature gas injection.Numerical simulation of thermal enhanced air sparging for field site shows that the conduction radius of temperature is 2-4 m and the influence scope of the pollutants could expand to the area within a 10 m radius,which is about 40%-50%larger than normal AS in winter.