Integrated Assessment of Alternative Management Strategies for PFAS-contaminated Wastewater Residuals

Farmhouse and field in autumn, Pittsfield, Maine
Maine farm in autumn. Photo: Hank Shiffman, Shutterstock

Institution: University of Maine
Sponsor: Water Resources Research Institute (104b) (2021)

Project Summary

An interdisciplinary research team examines the environmental, social and economic aspects of management options for PFAS, also known as “forever chemicals,” in Maine.

Per- and polyfluoroalkyl substances (PFAS) are synthetic organic chemicals with a unique ability to repel both water and oil that are used in a range of consumer products from nonstick cookware to breathable rain gear and food packaging. Though PFAS have been in wide-ranging use since the late 1950s, it is only in the last 20 years that their toxicity has been well documented.

Because these chemicals do not break down, they eventually end up in municipal and industrial wastewater sent to treatment plants. During treatment, much of the PFAS are removed from the wastewater and become concentrated in the wastewater sludge, or residuals, that remain. While these residuals could be a beneficial source of nutrients and soil amendments for farm fields, the presence of toxic contaminants is an ongoing problem. In 2019, Maine updated the practices for allowing the land application of wastewater treatment plant sludge – where all residuals must meet criteria which includes specific screening levels for PFAS.

With this management option for wastewater residuals no longer available, the Maine Department of Environmental Protection (DEP) requested research assistance from the Mitchell Center for suggestions on how best to manage the PFAS-contaminated material.

An interdisciplinary research team is examining the environmental, social and economic consequences of a range of management options for PFAS-contaminated wastewater residuals. The team includes expertise in aquatic ecosystems, environmental engineering, wastewater management, economics and social science, and risk perception and decision-making.

The project will generate a survey of the general public’s perception of risks from PFAS, original data on PFAS movement in landfill liner material, and a summary document comparing management alternatives for PFAS-contaminated wastewater residuals.

Project Update

This project began as a detailed interdisciplinary study of available options for the disposal of wastewater sludge, a primary source of ground and surface water contamination with PFAS (per- and poly-fluoroalkyl substances). A forty-year practice of spreading wastewater sludge on farm fields as fertilizer and soil amendment has contaminated dairy and vegetable farms with this persistent and harmful class of chemicals. The study examined social and engineering factors influencing management alternatives to the land application of wastewater sludge. The Noblet Lab (Economics) designed and administered a survey of public knowledge and perceptions of risk of the PFAS contamination problem, which resulted in empirical evidence that Maine residents hold strong preferences for addressing PFAS contamination in Maine. Maine residents are willing to contribute financially towards solutions and also hold preferences for how the taxpayer raised funds are used. However, unequal baseline knowledge regarding risks and exposure pathways increases the urgency for science communication to the public. The Apul Lab (Civil and Environmental Engineering) completed cutting edge research on adsorption of PFAS substances (PFOS, PFOA, PFBS and PFBA) to four types of high-density polyethylene-geosynthetic membrane type landfill liners and tested their integrity based on standardized American Society for Testing and Materials (ASTM) methods to resist tensile strength, punctures and incidental damages and so maintain an effective barrier to the movement of PFAS-contaminated landfill leachate into surrounding groundwater. Further, the interdisciplinary team reviewed the initial findings from the Maine Dept. of Environmental Protection on PFAS concentrations in wastewater sludge in relation to: 1) spatial patterns for PFOS and PFOA; 2) relative occurrence frequencies of PFOS and PFOA; 3) volumes of wastewater treated; and 4) potential local sources of PFAS. Graduate students and researchers presented our findings at four regional and national conferences.

Lead Researcher

Research Team

  • Onur Apul, Assistant Professor, Dept. of Civil and Environmental Engineering, and Mitchell Center Faculty Fellow, UMaine
  • Caroline Noblet, Associate Professor, School of Economics, and Mitchell Center Faculty Fellow, UMaine
  • Jean MacRae, Associate Professor, Dept. of Civil and Environmental Engineering, and Mitchell Center Faculty Fellow, UMaine
  • John Peckenham, Research Associate, Mitchell Center, UMaine

Project Partners

  • Chris Evans, Bureau of Remediation & Waste Management, Maine DEP
  • Victoria Eleftheriou, Deputy Director, Bureau of Remediation & Waste Management, Maine DEP
  • Patrick MacRoy, Deputy Director, Defend Our Health
  • Sharon Treat, Senior Attorney, Institute for Agriculture and Trade Policy
  • Ned Beecher, Special Projects Manager, NE Biosolids Research Association
  • Janine Burke-Wells, Executive Director, NE Biosolids Research Association
  • Mark Hutchinson, Extension Professor (compost), UMaine Cooperative Extension
  • Richard Kersbergen, Extension Professor (dairy), UMaine Cooperative Extension

Resources

Presentations

  • Kopec, D., Apul, O.G., Moavenzadeh, S., Noblet, C. Shea, M., Zimmerman, C., Peckenham, J. The Forever Chemicals: PFAS in Maine, What they are, where they come from, and what can we do about them. UMaine Mitchell Center Sustainability Talks. April 4, 2022
  • Shea, M., Zimmerman, C., Noblet, C.. Integrated assessment of alternative management strategies for PFAS-contaminated wastewater residuals. 2022 Maine Sustainability and Water Conference. March 31, 2022
  • Noblet, C., Shea, M., Zimmerman, C. Forever chemicals that need right-now solutions: Citizen preferences for addressing PFAS. NAREA, Mystic, CT. 2022
  • Moavenzadeh, S., Kopec, D., Apul, O.G. The interaction of per- and polyfluoroalkyl substances (PFAS) with landfill geomembrane and impact of liner integrity on PFAS seepage. EREF Intercontinental Landfill Research Symposium, September 2022