PFAS in Sewage Sludge: What wastewater experts are saying

At a glance

• The assessment is a draft requiring a 60-day public comment period, and it does not constitute a regulation with which utilities must comply.
• The assessment uses a model to identify risk in a hypothetical scenario of a farm family that consumes water and food from land upon which biosolids are land-applied.
• Due to a lack of data, a model of sewage sludge incineration was not included in the assessment, although qualitative analysis was provided.

On January 14, 2025, the U.S. EPA released its Draft Sewage Sludge Risk Assessment for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Though the assessment has long been expected, its content and context has raised more questions than it has answered. “What does this mean for the short-term? How about the long-term?” And, perhaps most importantly, “What actions should utilities consider taking right now?” Black & Veatch experts break down these questions and more about the evolving regulatory pressures surrounding PFAS.

1. Why did U.S. EPA release this draft assessment, and why is it important?

The EPA is following up on its commitment to reduce environmental pollution from per- and poly-fluoroalkyl substances (PFAS) as defined in the Agency’s PFAS Strategic Roadmap. The risk assessment for PFOA and PFOS in biosolids was identified in the roadmap as a key action to advance agency objectives and is a potential first step on the road to regulating these pollutants under the Clean Water Act (CWA). This could mean new limits on PFOS and PFOA in biosolids that impact the management options and costs for these materials.

2. Is this a new regulation?

This draft risk assessment is not a new regulation. The agency has explicitly stated that the draft risk assessment is not a rule and further noted that it “does not compel action by states or others.” Despite these clear caveats, there are concerns that some states may adopt draft risk assessment findings to set new state rules.

3. What did the draft risk assessment investigate?

The EPA investigated PFOA and PFOS as they are commonly found in biosolids (and other materials), targeting outlets covered under the 40 CFR 503 rule (although the outlets received different levels of study).

The assessment focused on land application – specifically, the risk posed to a hypothetical farm family that consumes primarily water, crops and/or livestock from lands that received biosolids or are near land application fields. The EPA also modeled potential risks for people drinking water originating near surface disposal sites (for a span of 10 years). Sewage sludge incineration, also regulated under the 503 rule, was qualitatively assessed, but EPA did not model that scenario due to significant data gaps.

For land application, the agency emphasized that they did not assess potential risks to the general population, who consume foods from a variety of sources. Moreover - it is important to note that biosolids are applied to less than 1% of the croplands in the United States – and some of the crops grown are not intended for human consumption. Both the diversity of typical American diets, coupled with the relatively small acreage receiving biosolids lowers the potential risks to the general public and the food supply.

4. What were the assessment’s findings and are they significant?

The EPA concluded that 1 µg/kg (ppb) of PFOA or PFOS exceeded its human health risk thresholds for the narrow scenarios it studied. EPA findings could be significant – depending on next actions – as most biosolids have PFOA and PFOS concentrations above 1 ppb.

For perspective, several states have enacted regulatory strategies that set 20 µg/kg (ppb) of PFOA and/or PFOS as a threshold to assess whether source reduction efforts are needed, with higher thresholds (100 µg/kg or ppb in Michigan, for example) above which biosolids cannot be land applied.

5. What is the path to possible regulation based on draft assessment findings?

There are multiple steps between the release of the draft and possible regulation – all of which carry some level of uncertainty.

60-day Public Comment Period: First, the draft is subject to a 60-day public comment period, which began on January 14, 2025, and the final document may differ from the draft, pending EPA responses to comments received. Comments are expected to be extensive, and multiple biosolids groups and scientists plan to provide extensive feedback on the draft assessment to the EPA.

After draft finalization: Once the draft risk assessment is finalized, the EPA can move to the critical next step: determining whether new biosolids limits for PFOA and PFOS are appropriate via their “risk management” process. This process considers economic and legal concerns to determine whether regulatory approaches to reduce risk are needed and practical.

White House strategic priorities: The progress of these steps – and future EPA actions with respect to PFAS – may depend on priorities of the new federal administration. Nonetheless, EPA’s support of source control for these pollutants (implemented by state regulators and utilities), coupled with regulatory activities already well underway to reduce PFAS in land applied biosolids, are expected to result in a continued focus on PFAS controls.

6. What can utilities be doing now?

Regardless of regulatory uncertainties, there are steps utilities can take today to reduce risks to their biosolids management programs.

Assess and Monitor PFAS Levels: Assessing PFAS levels in biosolids is a good proactive step to understanding the best approaches for current and future biosolids management decisions. Black & Veatch is actively engaged in PFAS research in biosolids and can develop a plan with utilities to sample, analyze and interpret PFAS results.

Limit PFAS Discharges: With treatment technologies still in their infancy, preventing PFAS from entering the headworks is currently the most cost effective and widely applied approach. A thorough sampling plan can be designed to understand sources of PFAS in a wastewater system so that utililty directors can proactively implement source reduction to lower PFAS levels in biosolids.

Black & Veatch helps utilities limit the amount of PFAS-containing material entering the wastewater collection system using various approaches, including working with industrial users, implementing practices that limit PFAS in the discharge, and promoting product stewardship to reduce PFAS in consumer products.

Understand and Leverage Technology Solutions: Explore technologies that can concentrate, separate and destroy PFAS where needed and minimize PFAS discharges. Black & Veatch can help utilities evaluate technologies for their specific needs. Its research through the Water Environment Federation along with bench-scale and pilot studies has evaluated conventional and emerging treatment technologies for liquids and biosolids that can concentrate, separate and destroy PFAS chemcicals.