地下水苯系物污染原位曝气修复模拟研究

Simulation on in-situ air sparging remediation of BTEX-contaminated groundwater

通过TMVOC软件模拟了苯系物在拟定渗流区"自然"环境条件下的污染物运移行为和原位曝气修复过程中的污染物衰减过程,确定了最佳曝气流量和所需要的曝气井数量及分布,并对修复效果进行了模拟.模拟显示,泄露过程中,在重力作用下,不饱和区的苯系物以竖直迁移为主,同时在毛细作用下横向迁移;在饱和区中以顺水流方向水平迁移为主,同时会溶解进入地下水,污染羽可到达含水层底部.从含水层底部的7个曝气孔同时以12m3/h的速率将空气注入时,只需180d即可完全修复苯系物污染区域.该条件下单井有效修复半径约5m,有效修复范围优于从含水层中部和中下部进行曝气.

TMVOC software was used to simulate the migration behaviour of contaminants under ＂natural＂ environmental conditions and attenuation process of contaminants during the in-situ air sparging process in a simulated vadose zone which was contaminated by BTEX.The best air injection rate as well as the quantity and distribution of the required aeration wells were determined,and further simulation was performed for remediation results.In the unsaturated zone BTEX mainly migrated vertically by gravity and migrated horizontally by capillary;in the saturated zone,however,the groundwater flow direction became the leading migratory direction of BTEX which dissolved into groundwater at the same time and whose pollution plume could reach the bottom of the vadose zone.It only required 180 days to completely remedy the BTEX contaminants under the condition that the air was injected into the aquifer at the rate of 12 cubic meters per hour through seven aeration holes located at the bottom of the vadose zone.Under these conditions,the effective remediation radius of a single aeration well is about 5 meters;the effective remediation scope is better than that of injecting the air into the vadose zone from the central or the lower part of the aquifer.