Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
J Contam Hydrol. 2011 Apr 1;123(1-2):50-64. doi: 10.1016/j.jconhyd.2010.12.006. Epub 2010 Dec 28.
Long-term performance is a key consideration for the granular iron permeable reactive barrier (PRB) technology because the economic benefit relies on sustainable operation for substantial periods of time. However, predictions on the long-term performance have been limited mainly because of the lack of reliable modeling tools. This study evaluated the predictive capability of a recently-developed reactive transport model at two field-scale PRBs, both having relatively high concentrations of dissolved carbonate in the native groundwater. The first site, with 8 years of available monitoring data, was a funnel-and-gate installation, with a low groundwater velocity through the gate (about 0.12 m d(-1)). The loss in iron reactivity caused by secondary mineral precipitation was small, maintaining relatively high removal rates for chlorinated organics. The simulated concentrations for most constituents in the groundwater were within the range of the monitoring data. The second site, with monitoring data available for 5 years, was a continuous wall PRB, designed for a groundwater velocity of 0.9 m d(-1). A comparison of measured and simulated aqueous concentrations suggested that the average groundwater velocity through the PRB could be lower than the design value by a factor of two or more. The distribution and amounts of carbonate minerals measured in core samples supported the decreased groundwater velocity used in the simulation. The generally good agreement between the simulated and measured aqueous and solid-phase data suggest that the model could be an effective tool for predicting long-term performance of granular iron PRBs, particularly in groundwater with high concentrations of carbonate.
长期性能是颗粒状铁渗透性反应屏障 (PRB) 技术的一个关键考虑因素，因为经济效益依赖于大量时间的可持续运行。然而，由于缺乏可靠的建模工具，对长期性能的预测一直受到限制。本研究评估了一种最近开发的反应迁移模型在两个现场规模的 PRB 中的预测能力，这两个 PRB 的原生地下水中都含有相对较高浓度的溶解碳酸盐。第一个场地有 8 年的可用监测数据，是一个漏斗和门的安装，门处的地下水速度较低（约 0.12 m d(-1)）。次生矿物沉淀导致的铁反应性损失较小，保持了相对较高的氯化有机物去除率。模拟的地下水中大多数组分的浓度在监测数据范围内。第二个场地有 5 年的监测数据，是一个连续墙 PRB，设计的地下水速度为 0.9 m d(-1)。测量和模拟的水相浓度的比较表明，PRB 中的平均地下水速度可能比设计值低两倍或更多。从岩芯样本中测量到的碳酸盐矿物的分布和数量支持了模拟中使用的地下水速度降低。模拟和测量的水相和固相数据之间的一般良好一致性表明，该模型可以成为预测颗粒状铁 PRB 长期性能的有效工具，特别是在碳酸盐浓度较高的地下水中。
