Grantee Research Project Results
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
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
Description:
The waste streams of landfills across the US have significant environmental impacts on the communities that surround them, which are usually underserved communities. Chemical contaminants, like per- and polyfluoroalkyl substances (PFAS), that are found in landfill leachate can end up in the water supply of those underserved communities, polluting the only water to which they have access. This study seeks to create a low-energy, low-cost technology for removing PFAS from landfill leachate so all communities can have access to cleaner water; in order to assess our technology’s ability to achieve this goal, we will use our technology to treat PFAS spiked DI water and synthetic landfill leachate. As part of this proposal, the PI will donate time to teach a hands-on engineering course to a group of undergraduates to develop a prototype treatment system under the supervision of a graduate student and senior undergraduate mentors who recently placed first in the national 2021 WERC (Waste Management Education Research Consortium) Environmental Design Contest for treating PFAS-containing water using a non-toxic, commercially available photocatalyst powered by ultraviolet light. This proposal will build on these results by using simulated leachate water and an even more active, non-toxic photocatalyst that can tolerate the high background concentration of organics.
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. Recent 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. 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.
Approach:
The undergraduate team will design and construct a new bench-scale UV/BN photocatalytic batch reactor. Using PFOA and PFOS as model PFAS in synthetic landfill leachate with variable humic acid content, pH, and TOC, tests will be conducted to ascertain performance information and appropriate operational conditions. PFAS and F- concentrations will be measured to confirm degradation. We will estimate energy efficiency of the system by determining EEO (electrical energy per one order) values, which is electrical energy required to reduce PFAS concentration by one order of magnitude (90%) in 1 m3 of contaminated water. We will also study the impact of real landfill leachate on UV/BN photocatalytic batch reactor performance. Undergraduate students, especially those from underrepresented minority groups and female students, will gain hands-on engineering experience with water treatment systems and environmental waters, while the mentoring students will gain leadership experience. Underserved communities near landfill sites will learn about the PFAS problem and current/novel treatment solutions.
Expected Results:
Providing an energy-efficient, non-toxic method to treat PFAS-containing wastewater emanating from landfills will reduce the amount of PFAS and other organic pollutants from entering the water supplies of nearby communities (which are typically disadvantaged), thus improving the health of the residents of those communities.
Supplemental Keywords:
photocatalysis, boron nitride, UVC, landfill leachateThe 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.