Managing PFAS in Biosolids: Strategies for an Evolving Regulatory Landscape

While PFAS regulation in drinking water has taken center stage in recent years, biosolids management presents an equally pressing challenge for water utilities. The presence of PFAS compounds in wastewater solids - combined with regulatory uncertainty and a patchwork of state-level actions - is forcing utilities to rethink their approach to residuals management.

In a recent In the kNOW webinar, Jacobs explored how utilities can address PFAS in biosolids with flexible, forward-looking strategies. Jacobs' global principal for residuals resource recovery, Todd Williams, shares key takeaways.

The current landscape

As of mid-2025, the U.S. Environmental Protection Agency (EPA) has not issued national regulations or guidance on PFAS in biosolids. However, the agency released a draft biosolids risk assessment for two common PFAS compounds - perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) - focused on specific farm family exposure scenarios. A public comment period for the draft assessment concluded Aug. 14, 2025.

This assessment has already influenced state actions. Several states - including Maine, Connecticut, Michigan and Wisconsin - have implemented bans or restrictions on land application of biosolids or restrictions on biosolids use with elevated PFAS concentrations. With no federal standard in place, the regulatory map continues to shift rapidly, creating uncertainty for utilities.

The case for adaptive management

In response, utilities should implement adaptable biosolids strategies that account for evolving federal, state and local regulations. This includes monitoring state activity, planning for multiple end-use scenarios and investing in data collection to understand baseline PFAS concentrations and trends.

Importantly, PFAS concentrations in biosolids have decreased over time due to the phased-out production of PFOA (2002) and PFOS (2015). Still, residual contamination remains an issue, especially for systems relying on traditional solids treatment processes.

How treatment affects PFAS in biosolids

Understanding how various treatment technologies impact PFAS concentrations is critical. Here's an overview of how common and emerging processes affect PFAS levels:

Anaerobic Digestion (AD): AD is widely used for biosolids stabilization, but PFAS concentrations often remain unchanged - or may even increase slightly. This can be due to precursor transformation or the concentrating effect from volatile solids reduction. Longer retention times or pretreatment methods do not appear to significantly reduce PFAS levels.

Composting: Composting results vary widely depending on sludge type, bulking agent used and process design. Aerobically processed sludges and digested materials generally exhibit lower precursor transformation. In some cases, recycling bulking agents can lead to increased PFAS due to sequestration and release. Site-specific testing is essential.

Thermal drying: Once considered a potential concern, drying processes have shown promise for reducing measurable PFAS - particularly precursors. Multiple studies show total PFAS mass reductions and lower concentrations in final biosolids products. However, outcomes depend on dryer type and operating parameters used, with rotary dryers generally showing good potential to reduce PFAS concentrations in the dried product.

Pyrolysis and gasification: Advanced thermal treatment is one of the most effective methods for reducing PFAS in biosolids. Pilot studies and full-scale tests indicate PFAS destruction rates of 85-95%, depending on temperature and feedstock. For example, testing of Class A dried biosolids run through pyrolysis systems at 500-700°C resulted in non-detect levels in final char. While promising, these technologies require significant capital investment and require pairing with drying systems. Utilities considering pyrolysis must also evaluate condensate and off-gas management to ensure complete PFAS containment.

Planning for the unknown

Given the uncertain regulatory trajectory, utilities must weigh the risk of PFAS detection against the cost of proactive treatment upgrades. Here are several key recommendations: