Grantee Research Project Results
Final Report: Chemical-free UV unit that degrades PFAS in landfill leachate using non-toxic boron nitride
EPA Grant Number: SU840587Title: Chemical-free UV unit that degrades PFAS in landfill leachate using non-toxic boron nitride
Investigators: Wong, Michael S , Samba, Joshua C , Nelson, Abraham , Sandoval, Johnphillip , Pillar, Amelia , Vaddiraju, Rishi , Tijani, Kamal , Heck, Kimberly N
Institution: Rice University
EPA Project Officer: Spatz, Kyle
Phase: I
Project Period: August 1, 2023 through July 31, 2024
Project Amount: $25,000
RFA: 19th Annual P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet Request for Applications (RFA) (2022) RFA Text | Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Sustainable and Healthy Communities
Objective:
Per/polyfluoroalkyl substances (PFAS) have been detected in landfill leachate due to their widespread applications in commercial, industrial, and household products, including surfactants, firefighting foams, and even drinking straws. Hazardous waste facilities, like landfills, have been disproportionately placed in communities where most residents are low income or people of color. This makes the need for effective and affordable water treatment technologies even more urgent. Published research by our group at Rice University showed that commercially available boron nitride (BN) photocatalytically degrades PFOA using UVC light, and is 10x more effective than the benchmark photocatalyst TiO2 on a per-photon basis.1 The UVC/BN system was also effective for the degradation of other PFAS, including short chain perfluorinated carboxylic acids (PFCAs), and perfluooctanesulfonic acid (PFOS). We have since extended our investigations to other BN-based materials, and our latest data indicate our best BN material shortens PFOA half-life t½ to an unprecedentedly short 6 min at room temperature. PFOA was non-detectible after 40 min, and the fluoride released at the end of the experiment (13 ppm) was 39% of theoretical maximum. Longer UVC treatment would increase fluoride ion formation (direct evidence of C-F bond breaking) due to mineralization of the shorter-chain intermediates. Reducing PFAS contamination in landfill leachate directly affects the quality of water available to the underserved communities surrounding these landfills. In addition, this technology can be applied to landfill leachate, and other PFAS contaminated water streams, across the planet, allowing many people to enjoy the prosperity of cleaner water.
Summary/Accomplishments (Outputs/Outcomes):
Due to the pressing need for effective and affordable water treatment solutions, our team aimed to explore the ability of BN/UVC photocatalysis to break down PFAS in landfill leachate. Using a solution of DI water spiked with ppb levels of PFBA, PFPeA, PFHxA, PFHpA, and PFOA as our contaminated water source, we were able to successfully lower the PFOA concentration by ~99% after 6 hrs of reaction.
Using ArcGIS, our team also examined the location of known and suspected PFAS occurrences, socially vulnerable communities (i.e., communities with increased susceptibility to the adverse impacts of natural hazards due to systemic barriers and structural inequalities), and landfill sites in the Harris County area to better understand the relationships between these variables. We found that areas with a high SVI (> 0.51) were not only more likely to be near a landfill but were also found to be near a known or suspected PFAS occurrence. Providing an energy-efficient, non-toxic method to treat PFAS-containing wastewater produced by landfills will reduce the amount of PFAS and other organic pollutants entering the water supplies of nearby communities, potentially greatly improving the health of adjacent communities.
Conclusions:
Our BN/UVC technology effectively removed PFOA at ppb levels in the presence of short-chain PFAS compounds. We predict our system can be further optimized to improve the catalyst's effectiveness at destroying the shorter-chain compounds. We also observed trends related to PFAS occurrences, landfill locations, and socially vulnerable areas in the US and Harris County, TX. Areas with a high SVI (> 0.51) were often near landfill sites and PFAS occurrences, demonstrating the need for affordable and effective PFAS destruction technologies for these communities.
Supplemental Keywords:
photocatalysis, boron nitride, UVC, landfill leachate, PFASThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.