PFAS in Biosolids: The Federal Regulatory Landscape

As the Environmental Compliance & Emerging Contaminants Program Manager at Pace®, I am often asked for my insights on current and pending legislation. Biosolids, in particular, are gaining increased attention from the media, the public, and legislators across the country. Recently, Nick Nigro, Pace® PFAS Product Manager, and I conducted a webinar on PFAS in biosolids. I began the presentation by discussing the current regulatory landscape. In this post, I’ll recap my comments on the federal regulatory landscape and add some perspectives I didn’t have time to get into in the webinar.  

Also, if you’re interested in the test method details, I encourage you to watch the complete webinar. Nick did a great job reviewing some of the challenges of analyzing PFAS in biosolids. He also highlighted findings from our recent study into liquid biosolids and reporting limits for two biosolids test methods: EPA 1633 and ASTM D8535.  

Watch: Biosolids Analysis for PFAS: Challenges, Considerations, and Options  

Biosolids vs. Wastewater Sludge: What’s the Difference? 

As many of you likely know, 40 CFR Part 503 (Part 503) is the federal regulation that covers wastewater sludge/biosolids. This code establishes standards for the use of sewage to protect public health and the environment. Currently, Part 503 does not address PFAS contamination, but we’ll get into that in a moment. 

The terms sludge and biosolids are often used interchangeably, even here at Pace®. However, there are nuances to these terms that you should be aware of. Part 503 uses the term sludge 636 times, and the term biosolids 0 times. Biosolids is apparently the term the industry itself developed for marketing and public perception purposes when land applying sludge. US EPA has adopted the use of the term as well even though it doesn’t include it in Part 503 – see Land Application of Biosolids | US EPA 

Within Part 503, sewage sludge is broken down into Class B, Class A, and Class A-EQ (Exceptional Quality). Class B sludge has been minimally treated for pathogens (fecal coliforms, salmonella, enteric viruses, etc.) so it has the most restrictions in terms of land-application and disposal, for example limiting site access for humans and grazing animals. Class A sludge has been further treated to lower pathogen levels and heavy metals (arsenic, lead, cadmium, copper, molybdenum, mercury, nickel, selenium and zinc.) This type of sludge is often referred to as biosolids and can be land-applied to sites like parks and golf courses. Class A-EQ biosolids meet the most stringent pollutant, pathogen, and vector attraction reduction limits defined in Part 503.  These biosolids may be distributed for land-application and are often sold directly to the public for use in home gardens and lawns.  

How’d the PFAS Get There? 

There’s a certain “eww” factor when talking about wastewater sludge or biosolids because it conjures up images of human waste. While that’s certainly part of the “bio” in biosolids, the PFAS contribution to the wastewater stream from human waste is low compared to industrial discharges. Rather, there are five major contributors to PFAS in biosolids, including:  

Industrial wastewater discharge – Industrial producers and users of PFAS chemicals around the country send their wastewater to their municipal wastewater treatment plant.  

Stormwater runoff – The stormwater runoff from commercial facilities that use or produce PFAS can contain PFAS. If legacy AFFF has been used on site to fight a fire or in a training exercise, the stormwater runoff is almost certain to contain elevated levels of PFAS. In most municipalities, this runoff is treated at the local wastewater treatment facility.

Domestic wastewater – Wastewater produced from everyday activities, such as washing stain-resistant clothing and the use of certain cleaning and personal care products, can contain PFAS. This is one of the reasons many states are so focused on bills banning or limiting the use of PFAS in consumer goods. 

Landfill leachate – Many studies have shown that landfill leachate from municipal sites almost universally contain elevated levels of PFAS. Of particular concern are the long-chain PFAS, such as PFOA and PFOS. However, leachate can also be a vector for contamination by other PFAS compounds, including PFAS precursors. 

Water treatment processes – Depending on the analysis techniques used, PFAS precursors may not show up as PFAS in a wastewater lab report. However, these PFAS precursors can be converted into more toxic, terminal PFAS by traditional wastewater treatment processes. 

Federal Activity Concerning PFAS in Biosolids 

At this point, it’s accurate to say that PFAS in biosolids aren’t yet regulated at the federal level. That may change in the very near future because to say that nothing is going on at the federal level couldn’t be further from the truth. 

Addition of PFAS to Part 503 – Let’s start by discussing 40 CFR Part 503. As mentioned already, PFAS are not regulated by Part 503. To add them, EPA is required to collect data and conduct risk assessments. The process for adding a compound can be long, but they have moved the ball forward in recent years.  

In 2023, the EPA proposed studying PFAS in wastewater sent to Publicly Owned Treatment Works (POTWs). Not long after this Information Collection Request (ICR) was proposed, my colleagues and I conducted a webinar on it: US EPA Information Collection Rule Proposal for PFAS and NPDES. The ICR was sent for approval to the Office of Management and Budget in October 2024. As of yet, it has not been finalized. It’s possible that the OMB hasn’t acted on the ICR because the EPA is in the process of redefining it. See my comments below on ELG Preliminary Plan 16. 

In addition, the EPA published a draft risk assessment for PFAS in biosolids in January of 2025. After extending the public comment period a couple of times, it closed in August. As usual, the comments came from all corners – individuals, organizations, associations, businesses, etc. Now the agency has the monumental task of combining through the over 25,000 comments received before drafting a final rule.  

Effluent Limitation Guidelines – While effluent limitations don’t directly regulate PFAS in biosolids, these limits can have an impact. Lowering PFAS levels in industrial discharge set for wastewater treatment would obviously also lower PFAS levels in the resulting biosolids. 

As outlined in ELG Plan 15, the EPA had already determined to establish limits on PFAS in effluent from landfills. In addition, the agency announced its intention to study PFAS in wastewater discharge from textile mills, airports, electrical components, and the pulp, paper, and paperboard industry. Preliminary Plan 16 builds on Plan 15, adding a more generic ICR (possibly broader that the currently proposed ICR), studying PFAS in the effluent from PFAS manufacturers and the metal finishing industries, and issuing an Advanced Notice of Proposed Rulemaking (ANPRM) for the Organic Chemicals, Plastics, and Synthetic Fibers Industry (OCPSF). The OCPSF industry includes PFAS manufacturers, but it can also include manufacturers of synthetic textiles, e.g., some waterproof fabrics and carpets. 

As of yet, the ELGs for landfills have not yet been proposed and Plan 16 has not yet been finalized. However, as I discussed in a recent post, the Spring 2025 Unified Agenda included the publication of a Notice of Proposed Rulemaking (NPRM) in January of 2026 for ELGs for PFAS manufacturers.  

PFAS in NPDES – Finally, the Spring 2025 Unified Agenda also included the addition of PFAS to National Pollutant Discharge Elimination System (NPDES) permit applications. Including PFAS in NPDES permitting will provide more data for future rulemaking. In addition, when ELGs are established for certain industries, they will be enforced through NPDES permitting.  

More to Come 

While there are still many unknowns, there is one thing we know for certain: the PFAS regulatory landscape is constantly changing. Although I only had space to touch on the federal level in this post, I also talked about what’s happening at the state level in the webinar. At this time, six states have laws on the books regarding PFAS in biosolids. That’s likely to increase when state legislatures begin meeting again in 2026. As always, we’ll be watching and offering our perspectives as the PFAS regulatory landscape continues to evolve. If you have questions or need more info on biosolids testing and analysis, we’re here to help.