摘要
空气注射是原位修复地下水中挥发性污染物的有效方法之一,但是因为缺乏现场数据,目前系统设计主要依据经验.为了获取合理设计参数,以北京某焦化厂地下水苯污染区域为例,结合现场试验,采用Petrasim中的TMVOC模块对空气注射进行了设计参数优化与修复模拟研究.现场试验得出最佳注气速率为23.2 m3.h-1,影响半径为5 m.模型对现场试验过程中地下水压力变化进行了模拟,模拟结果与实测结果吻合较好.模型对注气位置进行优化,最佳为底部注气;以底部注气方式对注气速率进行优化,得出最佳注气速率为20 m3.h-1,与现场试验结果相近;在最佳注气位置与注气速率下,影响半径为3m,现场测试结果比该值偏大,这主要是因为现场测试参数主要指示地下水上部与非饱和带中气流变化,而气流范围在接近地下水面处开始迅速增大,比地下水中实际气流范围要大.依据场地地质参数,利用优化参数,对修复过程进行了模拟研究,结果表明,修复过程中逐渐将污染物浓度已经达标区域的注射井关停的修复方式比修复过程中所有注射井一直开启的修复效果要好.采用注射井逐个关停的修复方式注气90 d后,该场地污染物浓度从371 000μg·L-1下降到1μg·L-1.
Air sparging（AS） is one of the in situ remedial technologies which are used in groundwater remediation for pollutions with volatile organic compounds（VOCs）.At present,the field design of air sparging system was mainly based on experience due to the lack of field data.In order to obtain rational design parameters,the TMVOC module in the Petrasim software package,combined with field test results on a coking plant in Beijing,is used to optimize the design parameters and simulate the remediation process.The pilot test showed that the optimal injection rate was 23.2 m^3·h^-1while the optimal radius of influence（ROI） was 5 m.The simulation results revealed that the pressure response simulated by the model matched well with the field test results,which indicated a good representation of the simulation.The optimization results indicated that the optimal injection location was at the bottom of the aquifer.Furthermore,simulated at the optimized injection location,the optimal injection rate was 20 m^3·h^-1which was in accordance with the field test result.Besides,3 m was the optimal ROI,less than the field test results,and the main reason was that field test reflected the flow behavior at the upper space of groundwater and unsaturated area,in which the width of flow increased rapidly,and became bigger than the actual one.With the above optimized operation parameters,in addition to the hydro-geological parameters measured on site,the model simulation result revealed that 90 days were needed to remediate the benzene from 371 000 μg·L^-1 to 1 μg·L^-1 for the site,and that the operation model in which the injection wells were progressively turned off once the groundwater around them was ＂clean＂ was better than the one in which all the wells were kept operating throughout the remediation process.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2012年第11期3927-3934,共8页
Environmental Science
基金
北京市科委重大专项(Z09040600930902)
北京市环保局项目
关键词
地下水
苯
空气注射
模型模拟
修复周期
groundwater
benzene
air sparging
simulation
repair time
