Zhu Zhang-Wen, Feng Shi-Jin, Zheng Qi-Teng, Chen Hong-Xin, Wei Heng
Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China.
State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China; Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China.
Sci Total Environ. 2024 Oct 20;948:174746. doi: 10.1016/j.scitotenv.2024.174746. Epub 2024 Jul 14.
Volatile organic compounds (VOCs) contamination at the groundwater may cause vapor intrusion and pose significant threats to human health. As a novel low-carbon mitigation technology, a horizontal permeable reactive barrier (HPRB) is proposed to remove the VOC vapor in the vadose zone and mitigate the vapor intrusion risk. To estimate the performance of HPRB in the contaminated site with a non-uniform source, a transient two-dimensional analytical model is developed in this study to simulate the VOC vapor migration and oxidation processes in the layered soil. The analytical model is verified against the experimental results and numerical simulation first and the parameter study is then conducted. The HPRB has good performance for the contaminated sites involving factors including deep source and local soil with low effective diffusivity. To consider the vertical heterogeneity of the local soil, the traditional equivalent homogeneity method has limitations in considering the horizontal migration of VOC vapor and is not suitable for the two-dimensional model. On the contrary, the artificial layered method based on the proposed analytical model has better accuracy and is recommended to be adopted in practice. Leading to the exponential decrease in the VOC vapor concentration at the ground surface, increasing the thickness of HPRB is an effective measure to enhance the performance of HPRB. The fitting exponential function can be applied to determine the minimum design value of the thickness of HPRB in practice.
地下水中的挥发性有机化合物（VOCs）污染可能导致气体侵入，并对人类健康构成重大威胁。作为一种新型的低碳减排技术，提出了一种水平渗透反应屏障（HPRB），以去除包气带中的VOC蒸汽，并降低气体侵入风险。为了评估HPRB在源强不均匀的污染场地中的性能，本研究建立了一个瞬态二维分析模型，以模拟分层土壤中VOC蒸汽的迁移和氧化过程。首先将分析模型与实验结果和数值模拟进行对比验证，然后进行参数研究。对于涉及深部源和有效扩散率低的局部土壤等因素的污染场地，HPRB具有良好的性能。考虑到局部土壤的垂直非均质性，传统的等效均质化方法在考虑VOC蒸汽的水平迁移方面存在局限性，不适用于二维模型。相反，基于所提出分析模型的人工分层方法具有更高的精度，建议在实际中采用。导致地表VOC蒸汽浓度呈指数下降，增加HPRB的厚度是提高其性能的有效措施。拟合指数函数可用于确定实际中HPRB厚度的最小设计值。
