Collaborative Research: ERASE-PFAS: Stabilization of Per- and Polyfluorinated Substances in Sewage Sludge Intended for Land-application

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In the United States (US), municipal wastewater treatment plants generate millions of tons of sludge per year. A significant fraction of this sludge is treated to produce a nutrient-rich product commonly referred to as biosolids. In the US, it is estimated that 7.2 million dry metric tons of biosolids are produced annually with approximately 55% of the biosolids generated used as soil amendments and sources of nutrients and organic matter in agriculture, farming, and land restoration. The detection of per- and polyfluoroalkyl substances (PFAS) in biosolids has raised serious concerns about the continuing and safe use of these solids in agricultural and farming land applications. PFAS are fluorinated organic chemicals that have emerged as priority pollutants during the last decade due to increasing concerns about their persistence, stability, and toxicity to humans and other living organisms as they accumulate in the environment. The overarching goal of this collaborative project is to identify, design, and synthesize suitable sorbents that can bind and sequester PFAS in biosolids. The successful completion of this project will benefit society through the development of new fundamental knowledge and sorbents to mitigate and eliminate the potential uptake of PFAS by plants when biosolids are used in agriculture and farming land applications. Additional benefits to society will be achieved through outreach and educational activities including the mentoring of a graduate student at the University at Albany, a graduate student at the University of Arizona, and a graduate student at Temple University. Approximately 55% of the biosolids derived from municipal sludge in the US are used as soil amendments, fertilizers, and sources of nutrients and organic matter in agriculture, farming, and land restoration. The increasing detection of PFAS in biosolids is raising significant concerns about their continuing and safe use in agricultural and farming land applications. Preliminary work by the Principal Investigators (PIs) of this project has established that certain sorbents can sequester and stabilize perfluoroalkyl acids (PFAAs) in biosolids. However, there are a number of unanswered questions about this sorption-based stabilization of PFAS in biosolids including whether it is applicable to a wide range of PFAS precursors, whether the stabilized PFAS will remain immobilized in soils in the long term, and whether the stabilized PFAS will be taken up by plants. The proposed research will address these critical knowledge gaps. To advance this goal, the PIs propose to carry out an integrated experimental and modeling research program to test the hypothesis that anionic, cationic, or zwitterionic PFAS precursors can be stabilized in biosolids upon amendments with suitable sorbents designed to enhance covalent binding (via head group interactions) and adsorption (via tail group interactions) between the target sorbents and PFAS precursors. The proposed research activities will be structured around three tasks: 1) Investigation of the transformations and distributions of PFAS precursors in model anaerobically digested sludge samples with or without added sorbents; 2) Investigation of the transformations and distributions of PFAS precursors in biosolid-soil systems with or without added sorbents using soybeans as a model plant; and 3) Evaluation of the fate, transformations, and distributions of 13C-label PFAS precursors and their mixtures in real sludge samples. The successful completion of this project has the potential for transformative impact through the development of new fundamental knowledge to advance the identification, design, and synthesis of efficient and cost-effective sorbents that can sequester and stabilize PFAS in biosolids to enable their continuing and safe use in agricultural and farming land applications. To implement the education and outreach activities of the project, the PIs plan to leverage established programs at the University at Albany (e.g., the Collegiate Science & Technology Entry Program) funded by the New York State Department of Education to recruit and mentor two middle or high school students and two undergraduate students to work on the project research team. In addition, the PIs plan to set up a website to disseminate the project research findings.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.