Holmes Ryan R, Hart Megan L, Kevern John T
University of Missouri-Kansas City, 5110 Rockhill Rd, Kansas City, MO 64110, United States.
J Contam Hydrol. 2017 Jan;196:52-61. doi: 10.1016/j.jconhyd.2016.12.005. Epub 2016 Dec 10.
Permeable reactive barriers (PRBs) are a well-known technique for groundwater remediation using industrialized reactive media such as zero-valent iron and activated carbon. Permeable reactive concrete (PRC) is an alternative reactive medium composed of relatively inexpensive materials such as cement and aggregate. A variety of multimodal, simultaneous processes drive remediation of metals from contaminated groundwater within PRC systems due to the complex heterogeneous matrix formed during cement hydration. This research investigated the influence coarse aggregate, portland cement, fly ash, and various combinations had on the removal of lead, cadmium, and zinc in solution. Absorption, adsorption, precipitation, co-precipitation, and internal diffusion of the metals are common mechanisms of removal in the hydrated cement matrix and independent of the aggregate. Local aggregates can be used as the permeable structure also possessing high metal removal capabilities, however calcareous sources of aggregate are preferred due to improved removal with low leachability. Individual adsorption isotherms were linear or curvilinear up, indicating a preferred removal process. For PRC samples, metal saturation was not reached over the range of concentrations tested. Results were then used to compare removal against activated carbon and aggregate-based PRBs by estimating material costs for the remediation of an example heavy metal contaminated Superfund site located in the Midwestern United States, Joplin, Missouri.
渗透性反应屏障（PRB）是一种利用零价铁和活性炭等工业化反应介质进行地下水修复的知名技术。渗透性反应混凝土（PRC）是一种由水泥和骨料等相对廉价的材料组成的替代反应介质。由于水泥水化过程中形成的复杂非均质基体，多种多模式、同步过程推动了PRC系统中受污染地下水中金属的修复。本研究调查了粗骨料、波特兰水泥、粉煤灰以及各种组合对溶液中铅、镉和锌去除的影响。金属的吸收、吸附、沉淀、共沉淀和内扩散是水合水泥基体中常见的去除机制，且与骨料无关。当地骨料可作为具有高金属去除能力的渗透性结构使用，然而，由于去除效果好且浸出率低，钙质骨料更受青睐。单个吸附等温线呈线性或向上弯曲，表明存在优先去除过程。对于PRC样品，在所测试的浓度范围内未达到金属饱和。然后，通过估算位于美国中西部密苏里州乔普林的一个典型重金属污染超级基金场地修复的材料成本，将结果用于比较与活性炭和基于骨料的PRB的去除效果。
