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PFAS & Biosolids

One of the big topics of discussion at the recent Pacific Northwest Pretreatment Workshop was PFAS. What are they exactly? What are the concerns associated with PFAS? How do they effect pre-treatment programs and waste water treatment plant (WWTP) operations?

Per-and Polyfluoroalkyl Substances (PFAS) are fluorinated chemicals with many uses and unique properties. They are stain repellant, flame resistant, non-stick, water resistant and good for coatings. Major PFAS sources include industrial sites, military fire training areas, and airports. They can also be found in to-go containers, personal care products, raincoats, electronics, and non-stick cookware.

(Above Image Source: Carollo Engineers)

Analyses show that WWTPs also have PFAS in their treated water, not because they produce or use PFAS but because it is in the sewage that enters the WWTP. Industrial discharges to the sewer, landfill leachate, or leaching of PFAS from consumer goods lead to PFAS in sewage. Traditional WWTP processes cannot remove PFAS and the compounds are among the most difficult to destroy due to their chemistry.

Rashi Gupta, Biosolids Technology Integration Lead, with Carollo Engineers, is researching the issue of PFAS in biosolids.

** Generally more cost-effective to limit or remove at the source vs. at drinking water or wastewater facilities.

** Challenging and costly to sample and analyze for PFAS.

** PFAS is an umbrella term for a lot of different compounds but two have been focus of most concern: Perfluorooctanoic acid (PFOA) and Perfluorooctanoic sulfonic acid (PFOS).

What’s the big deal?? PFAS are everywhere

PFAS have been linked to adverse health effects including: difficulty becoming pregnant, chronic kidney disease, cardiovascular disease, osteoarthritis, altered liver function, decreased vaccine effectiveness, and cancer.

Right Image Source: Rachel Carson Council,

Public concerns about PFAS impact day-to-day WWTP operations and costs. PFAS present real and perceived risks to aquatic and public health. Additionally, concerns about impacts on farming operations can endanger biosolids beneficial use and increase management costs.

The majority of biosolids are beneficially used in the US through land application to improve soil health, sequester carbon, and reduce fertilizer use. Concerns about PFAS leaching to soil and groundwater, plant uptake, and general human exposure may impact acceptance of land application. Other biosolids management options like incineration and landfilling present their own risks and landfilling does not destroy PFAS. Researchers around the world are conducting research to quantify risks, understand full fate and transport, and study technologies relative to PFAS destruction.

The EPA issued a PFAS Strategic Roadmap in October 2021 to outline planned work and a timeline for various intended actions, with reduction or elimination of PFAS in drinking water as the first priority. The agency has followed the Roadmap thus far, including issuing near-zero health advisory levels for drinking water and designating certain PFAS as hazardous substances under CERCLA. The EPA intends to finalize a risk assessment for PFOA and PFOS in biosolids in late 2024. This risk assessment will serve as a basis for determining whether regulation is appropriate and any subsequent biosolids standards.

In the meantime, some states like Maine and Michigan have implemented their own strategies for biosolids land application. Maine passed a practical ban on land application which has led to large increases in biosolids management costs. Michigan conducted a thorough study of PFAS in influent, effluent, and biosolids and imposed a source control strategy to reduce PFAS entering wastewater. The state also implemented a tiered strategy for biosolids land application which prohibits land application for biosolids that exceed a certain PFOS threshold while allowing controlled land application for solids that are less or minimally impacted. Throughout the Michigan strategy, source control is emphasized to identify contributors and reduce the chemicals at their sources. Many other states and wastewater agencies are now conducting studies to determine PFAS concentrations in influent, effluent, and biosolids.

Impacts on Biosolids Management and Treatment Plants

It is possible the cost of biosolids management costs could increase significantly if PFAS regulations limit current management practices. Jurisdictions throughout the country are seeing increases ranging from 1% to 455%. Smaller increases are seen where current management practices are not being impacted, such as where landfills are not limiting acceptance of biosolids. Larger increases are being realized where landfilling has been strained or beneficial use has changed to something else, such as landfilling or hauling long distances (like from Maine treatment plants to Canada).

Advanced thermal processing systems include promising innovative technologies like pyrolysis, gasification, supercritical water oxidation, and hydrothermal liquefaction) that may destroy PFAS in biosolids. It is important to note that research is ongoing about effectiveness of these technologies and whether PFAS are truly destroyed in all phases (liquid, solid, gas) or simply converted to other compounds that may also be harmful. Also, thermal processing technologies require substantial supporting systems which add to capital and operating costs and the technologies are still generally new or emerging without a lot of full scale operating experience.

So what to do? And what now?

Ms. Gupta suggests the following actions for pre-treatment professionals and agencies:

  • Track your own data and compare to published effluent data – identify outliers and potential point source contributors.

  • Identify potential industrial contributors in your service area.

  • Work with regulators on source control.

  • Stay on top of regulatory changes and research including the Water Research Foundation (WRF) projects 5031, 5042, 5082, 5107, and 5111 which can be accessed at

  • Seek out 3rd party reviewed info or peer-reviewed performance data, including holistic fate of PFAS.

  • Educate yourself, so you are prepared for public questions/outreach.

  • Don’t hedge yourself in relative to biosolids management – find options that allow for future changes/add-on processes if necessary.

  • The Water Research Foundation’s project WRF 5082 provides guidance for sampling, current data, and actions utilities can take to prevent PFAS entering wastewater.

And if your effluent data is higher than “typical”, start screening for known industries that can be PFAS sources:

• Organic Chemicals, Plastics and Synthetic Fibers (OCPSF) • Metal Finishing • Electroplating • Electrical and Electronic Components • Textile Mills • Landfills • Leather Tanning and Finishing • Plastics Molding and Forming • Paint Formulating • Pulp, Paper, and Paperboard • Airports • Military and municipal fire training areas as well as dry cleaners

And those industries that have historically been PFAS applicators and users:

• Teflon (polytetrafluoroethylene coated products including pans and floss) • Stain or water-resistant textile (clothing, carpet, couches, baby products) • Fire-fighting foam for jet fuel • Electroplating (chrome plating) • Cleaning or preparing semiconductors or circuit boards • Grease-repellent food contact paper (e.g. fast food containers or microwave popcorn bags)

It is important to remember source control works. Over time, PFAS/PFOA levels have dropped in blood and biosolids products. PFOS production was phased out in 2002, and PFOA production was phased out in 2015. There has been a 78% reduction of PFOS in biosolids from 2014 to 2018 and a 58% reduction in total PFAS.*

Many organizations and agencies are working on this issue. PPRC will stay involved in the effort to address the impacts of these “forever chemicals” to the environment and public health by sharing information, such as this article.

Thank you to Rashi Gupta, Biosolids Technology Integration Lead, with Carollo Engineers, for the information contained in this article, and in helping us present it here. You can see her presentation to the 2022 Pacific Northwest Pretreatment Workshop below.

PFAS Presentation by Rashi Gupta
Download PDF • 5.43MB

*From Ryan Batjiaka SFPUC – PFAS in Biosolids, Sept 16, 2020 Presentation, Lazcano et al. 2020; CDC 2019)

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