Per- and Polyfluoroalkyl Substances (PFAS) in Biosolids
Per- and polyfluoroalkyl substances (PFAS) are a group of manufactured chemicals that have been used in industry and consumer products since the 1940s because of their useful properties. There are thousands of different PFAS, some of which have been more widely used and studied than others. PFAS are long lasting chemicals, components of which break down very slowly over time.
When domestic sewage is treated in a wastewater treatment plant (WWTP), the liquids are separated from the solids to produce a semi-solid, nutrient-rich product known as sewage sludge. The terms “biosolids” and “sewage sludge” are often used interchangeably by the public; however, the EPA typically uses the term “biosolids” to mean sewage sludge that has been treated to meet the requirements in Part 503 and is intended to be applied to land as a soil amendment or fertilizer. Biosolids may contain PFAS and other contaminants that WWTPs receive from upstream dischargers including industrial facilities, landfills, and homes.
The EPA continues taking important steps to research, restrict, and remediate PFAS in the environment, including in biosolids.
- Learn more about PFAS
- Learn more about EPA’s PFAS Strategic Roadmap (pdf)
While these agency actions are underway, EPA recommends that states monitor biosolids for PFAS contamination, identify likely industrial discharges of PFAS, and implement industrial pretreatment requirements where appropriate. Doing so will help prevent downstream PFAS contamination and lower the concentration of PFAS in biosolids as described in Section C of EPA’s December 2022 memo entitled “Addressing PFAS Discharges in NPDES Permits and Through the Pretreatment Program and Monitoring Programs.”
- Read the EPA memo “Addressing PFAS Discharges in NPDES Permits and Through the Pretreatment Program and Monitoring Programs” (pdf)
EPA’s Actions for PFAS in Biosolids
Risk Assessment for PFOA and PFOS
The EPA committed in the agency’s PFAS Strategic Roadmap to conduct a biosolids risk assessment for two PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), in biosolids.
The assessment is currently underway and is expected to be published by the end of 2024. This is a necessary first step to determine whether regulation of these PFAS in biosolids is warranted under the Clean Water Act. After the risk assessment is complete, the EPA will engage in risk management to decide how to manage PFOA and PFOS in biosolids, if necessary. EPA will use the results of the risk assessment in addition to consideration of other factors including economics and technological feasibility in the risk management process.
The first step in conducting a risk assessment is problem formulation which 1) articulates the purpose for the assessment; 2) defines the problem (source and occurrence); 3) identifies the conceptual exposure pathways; and 4) presents data and tools used for analyzing and characterizing risk. The problem formulation process also involves engagement with states and tribes, risk managers, scientists, and members of the biosolids community regarding foreseeable science and implementation issues. Problem formulation for PFOA and PFOS was completed in November 2020.
National Sewage Sludge Survey
The EPA is planning to conduct the Biosolids Program’s next National Sewage Sludge Survey (NSSS) in collaboration with the Effluent Guidelines Program’s POTW Influent PFAS Study. This NSSS will focus on obtaining current national concentration data on PFAS in sewage sludge. The data generated by the NSSS will help inform future risk assessments and risk management actions for sewage sludge.
- Learn more about the agency's Current Effluent Guidelines Program Plan
- Learn more about the POTW Influent PFAS Study and the next National Sewage Sludge Survey
Interim Guidance on Destroying and Disposing of Certain PFAS and PFAS-Containing Materials That Are Not Consumer Products
The EPA published the first edition of this guidance as required by the National Defense Authorization Act for Fiscal Year 2020 (FY20 NDAA). The FY20 NDAA directed EPA to address the destruction and disposal of PFAS and specific PFAS-containing materials, including aqueous film-forming foam, contaminated media, textiles (other than consumer goods), and various wastes from water treatment. The 2024 updated interim guidance presents currently available information on the destruction and disposal of per- and polyfluoroalkyl substances and PFAS-containing materials, including sewage sludge.
Joint Principles for Preventing and Managing PFAS in Biosolids
EPA’s Office of Water, the Environmental Council of the States (ECOS), and the National Association of State Departments of Agriculture (NASDA) have jointly developed Principles for Preventing and Managing PFAS in Biosolids.
- Learn more about Joint Principles for Preventing and Managing PFAS in Biosolids