U.S. EPA. Office of Research and Development, Center for Environmental Solutions and Emergency Response, 26 MLK Dr, Cincinnati, OH, 45268, USA.
Battelle Memorial Institute, 505 King Ave, Columbus, OH, 43201, USA.
J Environ Manage. 2021 Oct 15;296:113069. doi: 10.1016/j.jenvman.2021.113069. Epub 2021 Jul 2.
A two-phased bench-scale study was conducted to evaluate various sorbents for possible use as chemical stabilizing agents, along with cement solidification, for possible use in an in-situ solidification/stabilization (immobilization) treatment process for per- and polyfluoroalkyl (PFAS) contaminated soils. The first phase involved sorption experiments for six selected PFAS compounds diluted in a water solution, using five selected sorbents: granular activated carbon (GAC), activated carbon-clay blend, modified clay, biochar, iron (Fe)-amended biochar, and Ottawa sand as a control media. The second phase involved chemical stabilization treatment (via sorption), using the most effective sorbent identified in the first phase, followed by solidification of two soils from PFAS-contaminated sites. Physical solidification was achieved by adding cement as a binding agent. Results from the first phase (sorption experiments) indicated that GAC was slightly more successful than the other sorbents in sorption performance for a 3000 μg/L solution containing a mixture of the six selected PFAS analytes (500 μg/L concentration each of shorter- and longer-chain alkyl acids), and was the only sorbent used in the second phase of this study. While the GAC, activated carbon-clay blend, and modified clay sorbents showed similar sorption performance for the longer chain analytes tested, both the activated carbon-clay blend and modified clay, exhibited slightly less sorptive capacity than GAC for the shorter-chain alkyl acids. Immobilization effectiveness was evaluated by soil leachability testing using Environmental Protection Agency (EPA) Method 1312, Synthetic Precipitation Leaching Procedure (SPLP) on the samples collected from two PFAS-contaminated sites. For the majority of the PFAS soil analytes, the addition of GAC sorbent (chemical stabilization) substantially reduced the leachability of PFAS compounds from the contaminated soil samples, and the addition of cement as a physical binding agent (solidification) further decreased leachability for a few of the PFAS compounds. Overall immobilization of PFAS analytes that were detectable in the leachate from two PFAS contaminated soils ranged from 87.1% to 99.9%. Therefore, it is reasonable to consider that the laboratory testing results presented here may have application to further pilot or limited field-scale studies within a broader suite of PFAS-contaminated site treatment options that are currently available for treating PFAS contaminated soils.
进行了两阶段的实验室规模研究，以评估各种可能用作化学稳定剂的吸附剂，以及与水泥固化一起，用于对受全氟和多氟烷基物质（PFAS）污染的土壤进行原位固化/稳定（固定化）处理。第一阶段涉及使用五种选定的吸附剂（颗粒活性炭（GAC）、活性炭-粘土混合物、改性粘土、生物炭、铁（Fe）改性生物炭和渥太华砂作为对照介质）对在水溶液中稀释的六种选定的 PFAS 化合物进行吸附实验。第二阶段涉及使用在第一阶段确定的最有效的吸附剂进行化学稳定化处理（通过吸附），然后对来自 PFAS 污染场地的两种土壤进行固化。通过添加水泥作为粘结剂来实现物理固化。第一阶段（吸附实验）的结果表明，在吸附性能方面，GAC 略优于其他吸附剂，对包含六种选定的 PFAS 分析物（每种 500μg/L 浓度的较短和较长链烷基酸混合物）的 3000μg/L 溶液进行吸附，并且是本研究第二阶段唯一使用的吸附剂。虽然 GAC、活性炭-粘土混合物和改性粘土吸附剂对所测试的较长链分析物表现出相似的吸附性能，但活性炭-粘土混合物和改性粘土对较短链烷基酸的吸附能力略低于 GAC。通过使用美国环保署（EPA）方法 1312（合成沉淀浸出程序（SPLP））对从两个 PFAS 污染场地采集的样品进行土壤浸出性测试，评估了固定化效果。对于大多数 PFAS 土壤分析物，添加 GAC 吸附剂（化学稳定化）可大大降低受污染土壤样品中 PFAS 化合物的浸出率，而添加水泥作为物理结合剂（固化）可进一步降低少数 PFAS 化合物的浸出率。在从两个 PFAS 污染土壤中浸出液中可检测到的 PFAS 分析物的总体固定化率为 87.1%至 99.9%。因此，可以合理地认为，这里提出的实验室测试结果可能适用于进一步的试点或有限的现场规模研究，作为目前可用于处理 PFAS 污染土壤的更广泛的 PFAS 污染场地处理方案的一部分。
