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Computational modelling to predict the longevity of a permeable reactive barrier in an acidic floodplain
Computers and Geotechnics ( IF 5.3 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.compgeo.2020.103605
Subhani Medawela , Buddhima Indraratna

Abstract This study introduces a novel computational approach that couples conventional geohydraulics with time-dependent changes of geochemical and biological parameters applied to a permeable reactive barrier (PRB) installed to treat acidified groundwater. The key objective of this PRB is to reduce excess acidity (low pH values), as well as to remove Al3+ and total Fe (i.e. Fe2+, Fe3+) from the acidic groundwater that flows through the PRB prior to being discharged as treated (neutralised) effluent to the environment. The governing equations characterising the geochemical reactions between the acidic influent and the alkaline PRB medium are incorporated into two finite-difference numerical codes, namely, MODFLOW and RT3D. In addition, biological clogging leading to reduced porosity of the PRB material over time is represented by explicit mathematical equations that are integrated with these geochemical numerical codes. The predictions from this coupled model made along the centreline of the PRB (i.e. one-dimensional flow) agree with the field data while demonstrating that the optimal treatment occurs predominantly in the proximity of the PRB inlet. The model also confirmed the potential benefit of using calcitic limestone (97% CaCO3) in the PRB, where a lifespan of about 16 years can be expected.

中文翻译:

用于预测酸性漫滩中可渗透反应屏障寿命的计算模型

摘要 本研究介绍了一种新的计算方法,该方法将传统的地质液压与地球化学和生物参数的时间相关变化相结合,应用于为处理酸化地下水而安装的渗透反应屏障 (PRB)。该 PRB 的主要目标是减少过量的酸度(低 pH 值),以及从流经 PRB 的酸性地下水中去除 Al3+ 和总 Fe(即 Fe2+、Fe3+),然后作为处理(中和)排放排放到环境中。表征酸性进水和碱性 PRB 介质之间地球化学反应的控制方程被合并到两个有限差分数值代码中,即 MODFLOW 和 RT3D。此外,随着时间的推移,导致 PRB 材料孔隙率降低的生物堵塞由与这些地球化学数字代码集成的明确数学方程表示。该耦合模型沿 PRB 的中心线(即一维流)做出的预测与现场数据一致,同时证明最佳处理主要发生在 PRB 入口附近。该模型还证实了在 PRB 中使用方解石石灰石 (97% CaCO3) 的潜在好处,预计使用寿命约为 16 年。一维流)与现场数据一致,同时证明最佳处理主要发生在 PRB 入口附近。该模型还证实了在 PRB 中使用方解石石灰石 (97% CaCO3) 的潜在好处,预计使用寿命约为 16 年。一维流)与现场数据一致,同时证明最佳处理主要发生在 PRB 入口附近。该模型还证实了在 PRB 中使用方解石石灰石 (97% CaCO3) 的潜在好处,预计使用寿命约为 16 年。
更新日期:2020-08-01
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