典型复杂地质条件下泡沫化表面活性剂强化曝气修复机理及应用研究

Remediation mechanism of in situ air sparing in contaminated site is one of worldwide hot research subjects in the field of environment and engineering geology recently. However, related theories lag behind engineering practice, which leads to poor remediation effect and difference between test data and theoretical analysis. Most of present research works about in situ air sparging of contaminated site are limited to homogeneous and simple geological conditions as well as common air sparging method. Therefore complicated geological conditions and foam-based surfactant enhancing mechanism are seldom considered. In this project, laboratory experiments and theoretical analysis are going to be conducted to study the following key problems: (1)illuminate the influences of foam-based surfactant enhancement on the flow pattern of air phase and remediation effect of in situ air sparging under typical complicated geological conditions; (2)reveal the interaction mechanisms between surfactant, VOCs contaminants, and soil; (3)establish the multiphase flow theory and corresponding model of in situ air sparging process, which considers the enhancing effect of the foam-based surfactant under typical complicated geological conditions; (4)build a lumped-parameter model for foam-based surfactant enhanced in situ air sparging, and verify the related theory and model with typical field remediation projects. The research results of this project will enrich and improve corresponding remediation theories of contaminated sites in the field of engineering geology, increase the design level of in situ air sparging under real complicated geological conditions, and provide important theoretical bases and technical supports for the promotion and application of this technique in China.

污染场地原位曝气修复机理研究是目前国内外环境与工程地质领域热点之一，但相关理论滞后于工程实践，常导致原位修复效果不佳和实测数据与理论计算不符。目前对于原位曝气修复研究多局限于均质单一土层等简单地质条件和常规曝气方法，对复杂地质条件影响及泡沫化表面活性剂强化作用机理缺乏考虑。本项目通过室内模型试验与理论分析，研究以下关键问题：(1)阐明典型地质条件下泡沫化表面活性剂对原位曝气气相运动与修复效果影响规律；(2)揭示表面活性剂-VOCs污染物-土体介质间相互作用机理；(3)建立特定复杂地质条件下考虑泡沫化表面活性剂强化作用的，原位曝气过程多相流分析理论和模型；(4)建立泡沫化表面活性剂强化原位曝气修复集总参数模型，利用典型现场工程案例对相关理论和模型进行验证。项目研究成果将丰富和发展工程地质学科污染场地修复理论，提高我国原位曝气修复设计水平，为该技术在我国的推广应用，提供重要的理论依据和技术支撑

污染场地原位曝气修复机理研究是目前国内外环境与工程地质领域热点之一，本项目针对复杂地质条件，通过一系列室内模型试验与理论分析，研究了泡沫化表面活性剂强化曝气修复机理及应用。项目主要取得以下几方面研究成果：.(1)对LNAPLs在非均质地层中的迁移过程进行了数值模拟，明确了低渗透镜体和多层介质对LNAPLs运移和分布的影响。.(2)通过原位地下水曝气二维模型试验中气流运动观测，查明了污染场地存在低渗透性透镜体时，气体在其中的运移规律。.(3)以Triton X-100作为表面活性剂，通过室内二维曝气模型试验对比分析，明确了泡沫化表面活性剂强化条件下曝气影响区变化规律。.(4)通过一维模型土柱试验，研究了表面活性剂溶液在不同浓度、不同砂土粒径、不同曝气流量等控制参数下的发泡性能。.(5)通过对有机物污染试样的低场核磁共振分析，查明了不同含油量和不同制样方法下油和水在粉土孔隙空间中的分布特征。.(6)通过一维、二维模型试验，揭示了表面活性剂强化曝气条件下，地下水表面张力和溶解氧变化以及气相运动规律。.(7)通过一维、二维模型试验，对表面活性剂强化曝气对甲基叔丁基醚（MTBE）污染场地修复效果进行了量化评价。.(8)通过数值模拟，阐明了表面活性剂强化曝气过程中液体表面张力变化对曝气影响范围、气相饱和度及污染物去除速率的影响规律。.(9)对常规曝气和表面活性剂强化曝气条件下饱和砂土中MTBE曝气修复传质过程集总参数进行了研究，提出了其测试和计算分析方法。.项目研究成果可为相关工程问题的设计与环境影响评价提供重要的科学依据和理论支撑。