Combined In-Situ / Ex-Situ Remediation of PFAS at Hazardous Waste Sites

土壤和地下水中的多氟和全氟烷基物质(PFAS)目前是通过提取 颗粒活性碳(GAC)或其他载体吸附异地处理受污染的地下水 仅将污染物转移到另一种仍需处理的介质的吸着剂。这是一个很长的- 因为1)土壤上吸附的全氟辛烷磺酸需要几十年的时间才能通过 地下水抽水和处理(P&T)，2)碳必须经常变化，3)处理(高 温度再生或焚烧)成本很高。最近，希金斯(Higgins，Chris，2016)《治疗与 多氟和全氟烷基物质的缓解策略“，报告#4322，水研究基金会，丹佛，科罗拉多州) 结果表明，低相对分子质量的PFAS对GAC的穿透速度快于其他化合物。此外，P&T 技术可能永远不会达到EPA健康咨询在含水层中的浓度。全氟辛烷磺酸是氟化的 美国环保局和全球卫生组织已确定的有毒、持久、 具有生物累积性和高度顽固性，耐水解、光解和生物降解。全氟辛烷磺酸 用于许多产品，包括用于扑灭军事和民用化学品火灾的水性成膜泡沫。 民用消防训练区，在那里它们是全氟辛烷磺酸对环境的共同来源。他们一直都是 在地表水中被发现，它们在使用多年后仍在地下水中存在，污染和威胁 饮用水供应。截至2014年，仅美国国防部就确定了664起火灾/坠毁/训练 仅限于可能存在全氟辛烷磺酸污染的地点。因此，迫切需要一种更具成本效益的 以及用于修复全氟辛烷磺酸污染场地的现场修复方法，这些污染场地在未来只会增加 好几年了。我们的团队将进一步开发和展示一种创新的现场/非现场相结合的技术，以 以符合成本效益的方式加快超级基金站点对全氟辛烷磺酸的处理。拟议的专有处理列车 结合1)无毒的环糖(CS)以从原位土壤中冲洗吸附的全氟辛烷磺酸，2)提取CS- PFAS与地下水的复合体和高效处理，可将99%+%的污染物去除到70ppt(百万分之几) 异地反应器，使用强化泡沫的工艺从提取的地下水中去除全氟辛烷磺酸 将全氟辛烷磺酸分离并浓缩到单独的反应堆中，在那里被销毁的一种形式 浓缩至70ppt的全氟辛烷磺酸。回注含低浓度CS改性剂的处理水 进入地下进行持续的含水层冲洗。在第一阶段，研究表明：1)PFAS可以有效地 从具有相对较小冲洗量的高度全氟辛烷磺酸污染的土壤中冲洗，以及2)全氟辛烷磺酸可以 有效地从提取的地下水中分离出来，并在浓缩物中销毁。实验室规模测试将 用于评估优化特定地点的PFAS从土壤中解吸、分离所需的参数 提取的CS-PFAS络合物，并在非原位反应器中最终破坏PFAS浓缩物。一个 将在第二阶段进行现场试点试验，以证明该工艺对全氟辛烷磺酸的处理。 1

Poly- and perfluoroalkyl substances (PFAS) in soil and groundwater are currently remediated by extracting the contaminated groundwater for ex-situ treatment via adsorption onto granular activated carbon (GAC) or other sorbents which only transfers contaminants to another media that still needs to be treated. This is a very long- term and expensive process because 1) it takes decades for the sorbed PFAS on soil to be extracted via groundwater pump and treat (P&T), and 2) the carbon must be changed frequently and 3) treatment (by high temperature regeneration or incineration) is costly. Recently, Higgins (Higgins, Chris, 2016 “Treatment and Mitigation Strategies for Poly and Perfluoroalkyl Substances”, Report #4322, Water Research Foundation, Denver, CO) showed that low molecular weight PFAS breakthrough GAC faster than other compounds. In addition, P&T technology may never achieve EPA Health Advisory concentrations in the aquifer. PFAS are fluorinated anthropogenic pollutants that the USEPA and global health organizations have identified as toxic, persistent, bioaccumulative and highly recalcitrant, being resistant to hydrolysis, photolysis, and biodegradation. PFAS were used in many products, including aqueous film-forming foams to combat chemical fires at military and civilian fire training areas where they are a common source of PFAS to the environment. They have been identified in surface waters and they persist in groundwater years after use, contaminating and threatening drinking water supplies. As of 2014, the U.S. Department of Defense alone has identified 664 fire/crash/training sites alone that potentially have PFAS contamination. Thus, there is a critical need for a more cost-effective and in-situ remediation approach for remediating PFAS contaminated sites that will only increase in the coming years. Our team will further develop and demonstrate an innovative combined in-situ/ex-situ technology to cost-effectively expedite treatment of PFAS at Superfund sites. The proposed proprietary treatment train combines 1) a non-toxic cyclic sugar (CS) to flush sorbed PFAS from the in-situ soil, 2) extraction of the CS- PFAS complex with groundwater and treatment in a high efficiency 99+% removal to 70 ppt (parts-per-trillion) ex-situ reactor that removes the PFAS from the extracted groundwater using a process to enhance foam formation that separates and concentrates the PFAS into a separate reactor where it is destroyed in the concentrate to 70 ppt total PFAS. The treated water with a low concentration of CS amendment is re-injected into the subsurface for continued aquifer flushing. In Phase I, it was shown that: 1) PFAS can be effectively flushed from highly PFAS contaminated soils with a relatively small flushing volume, and 2) the PFAS can be effectively separated from the extracted groundwater and destroyed in the concentrate. Bench scale tests will be used to evaluate those parameters needed to optimize site-specific PFAS desorption from soil, separation of the extracted CS-PFAS complex, and ultimate destruction of the PFAS concentrate in the ex-situ reactor. A site-specific field pilot test to demonstrate PFAS treatment by the process will be performed in Phase II. 1