CAREER: Transformation potential of per- and polyfluoroalkyl substances (PFAS) in drinking water distribution systems

全氟和多氟烷基物质(PFAS)是一种含氟有机化学污染物，由于其持久性、稳定性和对自然环境降解过程的抵抗力，通常被称为永久化学品。在过去的二十年里，在地表水系统(湖泊和河流)和地下水含水层中检测到的全氟辛烷磺酸越来越多，这些地下蓄水层是全美许多社区的饮用水来源。此外，在天然和工程水系统中，许多全氟辛酸可以通过非生物和生物途径转化为有毒的全氟烷基酸(PFAA)，包括全氟辛酸(PFOA)。迫切需要新的数据和知识，以促进对饮用水系统中全氟辛烷磺酸的去向、传输和反应的基本理解。这个职业项目的总体目标是调查和评估饮用水分配系统(DWDS)中全氟辛烷磺酸的非生物和生物转化，因为处理后的水通过分配系统到达客户的水龙头。为了推进这一目标，首席调查员建议将选定的全氟辛烷磺酸转化的实地研究与受控实验室和中试规模的实验相结合。该项目的成功完成将通过产生新的数据和基础知识来推动工程解决方案和政策建议的设计，以解决和减轻全氟辛烷磺酸的饮用水污染，从而使社会受益。还将通过学生教育和培训，包括指导乔治梅森大学的两名研究生，为社会带来更多好处。许多饮用水分配系统(DWDS)的环境条件与天然水系统相当，在这些系统中，已观察到全氟辛酸化合物和前体转化为有毒的全氟烷基酸(PFAA)，包括全氟辛酸(PFOA)。此外，DWDS的组件(如管道、水箱和水塔)可用作结垢/沉积物积累和生物膜形成的底物，这些生物膜导致/催化这些系统中溶解污染物的非生物/生物转化。这一职业项目将检验这样一种假设，即全氟辛烷磺酸在DWDS中的转化主要是由聚全氟苯磺酸化合物和前体在其鳞片和沉积物生物膜中积累的生物转化所介导的。为了验证这一假设，首席调查员(PI)建议评估和表征控制DWDS中全氟辛烷磺酸转化的化学和微生物过程，重点是美国大西洋中部地区的储存设施。这项研究的具体目标是：1)调查饮用水储存设施中的PFAS分配和转化，并为控制实验的设计开发方法和基础设施，以获得基本的见解；2)评估储水池/沉积物材料和环境参数对饮用水储存设施中PFAS分配和转化的影响；以及3)评估处理残留物对饮用水储存设施生物膜中PFAS转化的影响。该项目的成功完成有可能产生变革性的影响，通过产生新的基本知识来推进工程解决方案的设计和实施，以最大限度地减少和减轻饮用水储存设施和分配系统中的全氟辛烷磺酸污染。为了实施这个职业项目的教育和外展活动，PI建议利用乔治梅森大学(GMU)现有的课程和资源，开展关于化学教育的课程研究，以支持社区大学转学、环境工程(EE)非传统和传统学生的学习和成功。更具体地说，PI建议1)调查学生的化学准备、态度和人口统计对EE表现和兴趣的影响；2)评估学生在化学方面的表现与EE入门课程中概念掌握之间的相关性；以及3)利用从这项研究中获得的知识来设计课程，以弥补学生在化学准备方面的差距，并为学生成功完成GMU的EE本科教育做好准备。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic chemical contaminants that are commonly referred to as forever chemicals due to their persistence, stability, and resistance to natural environmental degradation processes. During the last two decades, PFAS have been increasingly detected in surface water systems (lakes and rivers) and groundwater aquifers which serve as sources of drinking water for many communities throughout the United States. In addition, many PFAS can be transformed through abiotic and biotic pathways in natural and engineered water systems to produce toxic perfluoroalkyl acids (PFAAs), including perfluorooctanoic acid (PFOA). There is a critical need for new data and knowledge to advance the fundamental understanding of the fate, transport, and reactivity of PFAS in drinking water systems. The overarching goal of this CAREER project is to investigate and evaluate the abiotic and biotic transformations of PFAS in drinking water distribution systems (DWDS) as the treated water transits through the distribution systems to customers’ taps. To advance this goal, the Principal Investigator proposes to integrate field studies of PFAS transformations in selected DWDS with controlled laboratory and pilot scale experiments. The successful completion of this project will benefit society through the generation of new data and fundamental knowledge to advance the design of engineering solutions and policy recommendations to address and mitigate PFAS drinking water contamination. Additional benefits to society will be achieved through student education and training including the mentoring of two graduate students at George Mason University. Many drinking water distribution systems (DWDS) exhibit environmental conditions comparable to those of natural aquatic systems in which the transformations of PFAS compounds and precursors to toxic perfluoroalkyl acids (PFAAs), including perfluorooctanoic acid (PFOA), have been observed. In addition, the components of DWDS (e.g., pipes, tanks, and water towers) can serve as substrates for the accumulation of scales/sediments and the formation of biofilms that cause/catalyze the abiotic/biotic transformations of dissolved contaminants in these systems. This CAREER project will test the hypothesis that PFAS transformations in DWDS are primarily mediated by the biotic transformations of PFAS compounds and precursors that accumulate in their scales and sediment biofilms. To test this hypothesis, the Principal Investigator (PI) proposes to evaluate and characterize the chemical and microbial processes controlling PFAS transformations in DWDS with a focus on storage facilities in the Mid-Atlantic region of the United States. The specific objectives of the research are to 1) investigate PFAS partitioning and transformations in drinking water storage facilities and develop methods and infrastructure for the design of controlled experiments to generate fundamental insights; 2) evaluate the effects of storage tank/sediment materials and environmental parameters on PFAS partitioning and transformations in drinking water storage facilities; and 3) evaluate the effect of treatment residuals on PFAS transformations in the biofilms of drinking water storage facilities. The successful completion of this project has the potential for transformative impact through the generation of new fundamental knowledge to advance the design and implementation of engineering solutions to minimize and mitigate PFAS contamination in drinking water storage facilities and distribution systems. To implement the educational and outreach activities of this CAREER project, the PI proposes to leverage existing programs and resources at George Mason University (GMU) to carry out curricular research on chemistry education to support learning and success for community college transfer, non-traditional and traditional students in environmental engineering (EE). More specifically, the PI proposes to 1) investigate the impact of student chemistry preparation, attitudes, and demographics on performance and interest in EE); 2) evaluate correlations between student performance in chemistry and mastery of concepts in introductory EE courses; and 3) use the knowledge gained from this research to design lessons to remediate student chemistry preparation gaps and prepare students for the successful completion of EE undergraduate education at GMU.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.