电阻加热处置污染土壤典型多环芳烃迁移规律及影响因素研究

Polycyclic aromatic hydrocarbons (PAHs) are the typical semi-volatile organic pollutants in the soil of industrial pollution sites. Soil electrical resistance heating (ERH) is an effective in-situ remediation technique to remove organic pollutants from soil. This project intends to study the action mechanism and influencing factors of ERH treatment of target contaminated soil by using the self-made ERH device and analyzing the remove characteristics of typical PAHs in two kinds of soils with large property differences. The mechanism of thermal desorption will be clarified by studying the influence of temperature on the environmental behavior of PAHs on soil-water interface, through the experiment of adsorption/desorption of soil pollutants under heating condition; based on the interface behavior, the remove rule of target pollutants in soil during ERH disposal will be clarified through soil electrical resistance heating experiment; the removal mechanism of target pollutants in ERH and conventional thermal disposal gases will be clarified by analyzing their occurrence patterns, through TG-FTIR, TG-MS and ERH methods; the interaction mechanism between ERH and its basic physical and chemical properties will be illuminated by analyzing the changes in the basic physical and chemical properties of the two kinds of soils before and after heating, and the optimal heating conditions will be selected. The results of this project can provide a theoretical foundation for the precise remediation of organic contaminated soil by electrical resistance heating.

多环芳烃（PAHs）是工业污染场地土壤中典型的半挥发性有机污染物，其修复治理势在必行。土壤电阻加热（ERH）是一种可有效去除土壤中有机污染物的原位修复技术。本项目拟利用自制土壤电阻加热小试装置，通过分析典型PAHs在两种性质差异较大的土壤中的迁移特征，研究ERH处置目标污染土壤的作用机制及其影响因素。通过加热条件下的土壤污染物吸附/解吸实验，研究温度对PAHs在土-水界面环境行为的影响，明晰其热脱附机制；基于界面行为理论，通过电阻加热实验，阐明土壤中目标污染物在ERH处置过程中的迁移规律；通过热重-红外联用、热重-质谱联用、ERH等手段，分析目标污染物在ERH及常规热处置气体中的赋存形态，明晰其去除机理；通过分析加热前后两种土壤基本理化性质的变化和ERH加热效率的差异，阐明土壤电阻加热与其基本理化性质之间的交互作用机制。相关成果可为电阻加热精准修复有机污染土壤提供理论依据。

随着我国工业化进程加快，工厂车间升级搬迁所遗留的土壤污染问题受到社会各界的重视，其中挥发性高、毒性高的多环芳烃类有机污染物受到广泛关注。土壤电阻加热作为原位热脱附技术的一种，近年来在场地修复案例中得到应用，是最有潜力的原位有机污染土壤处置技术之一。然而该技术主要控制参数并不明确，且存在效率低、耗时长的问题，需要阐明其控制参数与耦合高效氧化技术的可行性，从而提高该技术的适用范围。因此本文以多环芳烃为目标污染物，以电阻加热为主要处置手段，进行了土壤电阻加热处置、电阻加热耦合化学氧化实验，研究了电阻加热控制因素、电阻加热耦合化学氧化可行性、电阻加热对土壤微生物的影响等内容，主要结果如下：.1. 电阻加热主要控制因素为土壤水分、土壤盐分电场强度，本研究所用实验装置需要至少4 g盐溶液（0.1%）加热15 g土壤至目标温度（94 ℃）。电阻加热对多环芳烃的去除率高于常规加热处置，这与水的挥发性和污染物与水共沸有关。.2. 电阻加热处理后120 min，污染土壤中多环芳烃的去除率为21.63% （DBA） ~ 71.53% （Nap），去除率与多环芳烃的沸点呈负相关 （P = 0.002）。添加2.5 mmol/g 过硫酸钠可以使菲的去除率由35.90%升高至79.42%，苯并芘去除率由23.50%升高至85.47%。.3. 在电动输送后的电阻加热处置对高环多环芳烃的去除率达到76.32%，对多环芳烃总的去除率达到86.21%。证明了电阻加热耦合电动输送氧化剂处置多环芳烃污染土壤理论可行性。.4. 土壤100 ℃热处置后，土壤中微生物数量降低，但在短时间内恢复，并不受到土壤初始微生物数量的影响。

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