地下水曝气修复过程离心模型试验研究

Centrifuge modeling of air-sparging technique for groundwater remediation

为了研究地下水曝气修复机理及其影响因素,采用离心模型试验模拟地下水曝气修复过程,其中土体用透明玻璃珠代替以便于图像观察和分析处理,同时由于模型能够提高土体的应力水平,从而可以在较大范围内研究曝气压力的影响。离心模型试验得到了气体运动规律和曝气影响区域的特征。研究表明:土体中的气体流速随曝气压力增加而逐渐增大;曝气影响范围在曝气压力较小时随曝气压力增加而增大,当曝气压力持续增大超过临界压力时,影响范围将保持稳定;曝气影响范围随土体粒径的增大而减小,随离心加速度增大而减小;曝气影响范围为锥形,可以采用虚拟曝气点和稳定渗气夹角定量描述。试验成果可以为曝气修复系统的设计和运行提供参考依据。

Air sparging is one of the groundwater remediation techniques to clean up voltaic organic compounds.Based on the centrifuge tests employing glass beads as model soil,the process of air sparging is simulated under a wide range of sparging pressure and centrifuge g levels.The test results show that the increase of the sparging pressure improves the air flow velocity.There exists a critical sparging pressure,while the zone of influence（ZOI） expands with the increase of sparging pressure when it is lower than the critical value,and the ZOI decreases a little and then keeps constant when it is higher than the critical value.The ZOI decreases with the increase of soil particle size and g-level.The ZOI is cone-shaped and can be described by use of the virtual sparging point and cone angle.The test results provide valuable information for the design of air sparging system for groundwater remediation.