【作者】 李雨松；

【导师】 赵勇胜；

【作者基本信息】 吉林大学 ， 环境工程， 2009， 硕士

【摘要】 本文研究了空气扰动法(AS)对氯苯污染地下水的治理效果。空气扰动法(AS)是一种原位修复技术,被认为是去除饱和区土壤和地下水中挥发性有机化合物的最有效方法。它是与土壤气相抽提互补的一种技术,其目的是去除含水层中的污染物质。通过研究AS技术的不同影响因素在去除挥发有机污染物过程中的影响效果,得到了实验室条件下的确定最佳曝气流量为0.15m3/h。介质粒径越大,渗透系数就越大,越有利于空气扰动法对氯苯的去除。粒径较小时间歇曝气对氯苯的去除效率优于连续曝气,建议采用间歇曝气方式;粒径较大时两种曝气方式的去除效率接近,建议采用连续曝气方式,以缩短修复时间。氯苯与苯相互混合时有利于对氯苯的去除。通过二维模拟沙槽研究了不同曝气流量下空气扰动法对污染物的去除作用,以及对地下水流动对污染物扩散和迁移的影响。没有曝气时,氯苯浓度的减少主要依赖于地下水的流动作用,且氯苯随地下水的流动发生迁移,导致污染区域扩大。开始曝气后,注入空气形成的空气通道周围存在气液两相界面传质区域,氯苯通过扩散作用由传质区进入空气通道,进而被挥发去除。继续增加曝气流量,由于在同一区域注入了更多的空气,形成了更多的空气通道和传质区域,进而加强了对氯苯的气相分割作用和挥发作用,使得氯苯被更快的去除;注入空气的过程中产生的扰动作用降低了曝气区域的水力传导系数,进而减小了地下水的流速;水的流速降低增加了污染物在污染区域的停留时间,减少了因地下水流动导致的迁移,对污染物起到了阻截和控制作用,加强了空气扰动法对污染场地的控制;同时气液两相的相互扰动作用分割了介质中的氯苯并使其得到有效去除,最终使污染区域得到治理和控制。在曝气过程中,污染物的扩散和挥发作用是去除的主要作用,地下水的流动作用去除污染物所占比例较低。更多还原

【Abstract】 In recent years, environmental polluted incidents occur frequently along with the rapid development of economic and social. These incidents will bring in high concentrations of toxic volatile organic pollutants especially as explosions and leaks. This is a major threat to people’s health and the ecological environment.At present, human’s activities have resulted in a wide range of environmental pollution. The emissions, waste water, and the waste residue often directly or indirectly enter the soil and groundwater through air, water and other media during people’s living and producing. Once the soil and groundwater are polluted, the impact to the environment is continuous and irreversible. Facing such an unprecedented threat, to protect the soil and groundwater against pollution is receiving a growing concern. Studying the groundwater treatment technologies has become a new hot spot to the environmental engineering sciences and technical studies. Among these methods, air sparging is more and more widely used by its significant advantages such as high reducing efficiency to contaminants and low investment.In this paper, the effect of different impact factors is studied in the course of removing organic pollutants, and make sure the optimum aeration flow is 0.15m3/h under laboratory conditions. Greater the medium particle size is, greater the permeability coefficient is, and better the effect of removing chlorobenzene by air sparging is. When the particle size is smaller, intermittent aeration is suggested to use. When the particle size is larger, the removal efficiency of both two aeration mode is closed, and we suggests to choose continuous aeration in order to shorten the remediation time, It is better to remove chlorobenzene when it is mixed with benzene. This paper studies the effect of air sparging under different aeration on the removal of pollutants, and the impact of groundwater flow to the migration and diffusion of pollutants,and make sure the relative contribution between migration and evapotation on the removal of pollutants.When there is no aeration, the reduction of chlorobenzene concentration is mainly depends on the flow of groundwater, and the chlorobenzene’s migration by the flow of groundwater courses the expanding of contaminated area. After the beginning of aeration,the injected air will form air channels. There is gas-liquid mass transfer interfacial area around these channels. Chlorobenzene can enter into air channels through mass transfer zone by diffution and be removed by evapotation. Increasing aeration can inject more air into the area, and generate more air channels and mass transfer area. This strengthens the role of partition and evaporation to chlorobenzene, making the removing rate of chlorobenzene faster.The disturbance generated during the process of injecting air reduces the hydraulic conductivity in the aeration area, and reduces the flow rate of the groundwater. This can increase the pollutant’s residence time in the polluted area, reduce the migration caused by groundwater flow, and play a role in the pollutants’interception and control. At the same time, the disturbance role between liquid and gas cut up the chlorobenzene in the medium. In the end, the contaminated area is treated and controlled.During the aeration process, the diffusion and volatilization of the pollutants is the main removing effect, the effect of groundwater flow is lower.更多还原