Yes. No. Maybe. Depends on the circumstances. Requires more research.

Like so many questions about contaminants in the environment, the issue of perfluorooctane sulfonate, or PFOS, in biosolids raises both concerns and unanswered questions. The concern is whether PFOS, which makes its way into biosolids by way of wastewater treatment, could be taken up by crops grown in biosolids-augmented soils.

PFOS has been used for years as a stain repellent in carpet and clothing, and in firefighting foams and industrial processes. Like other contaminants, PFOS often ends up in wastewater and ultimately in biosolids.

It’s an emerging issue that has led at least two states to develop regulations halting biosolids land application. In March, the Maine Department of Environmental Protection issued a moratorium on the practice. In response, Ned Beecher, executive director of the North East Biosolids & Residuals Association, states, “Research and data to date do not indicate that PFOS in typical biosolids is a concern for drinking-water quality or human health.”

Similar restrictions, if adopted around the country, could have a serious impact on biosolids management, since an estimated 60% of municipal biosolids are land-applied. At the same time, industry professionals are urging caution. A webinar by the Water Environment Federation pointed out that PFOS in the environment is declining as manufacturers limit or eliminate its use. The presentation suggested that well-managed soil may be the best destination for PFOS, as it can be broken down in the natural cycle.

One researcher following this issue is Matt Simcik, Ph.D., an associate professor in the Division of Environmental Health Sciences at the University of Minnesota. His research broadly focuses on how and why organic pollutants end up in the air and water, especially in the Great Lakes region. His areas of expertise include the fate and transport of trace organic pollutants, especially per- and polyfluoroalkyl substances, or PFAS.

He shared his perspectives on PFOS in an interview with Treatment Plant Operator. The magazine welcomes other information and viewpoints on this subject from scientists, industry professionals and others with expertise.

TPO: Let’s sort out the acronyms — PFAS, PFOS and others.

Simcik: Originally, folks referred to perfluorochemicals, or PFCs. Now the accepted term is PFAS, which means per- and polyfluoroalkyl substances. It’s a catchall term. PFOS is specific to perfluorooctane sulfonate, the most commonly detected of the PFAS in the environment.

TPO: Where do these contaminants come from, and how do they get into sewers?

Simcik: They were used extensively in products such as stain and water protectants, nonstick cookware, food wrappers and coated paper. When products like clothing in which PFOS is present are washed, the contaminant ends up in the waste stream. Furthermore, because everyone has these in their systems from environmental exposure, we eliminate them through feces and urine.

TPO: How prevalent are these substances in the environment?

Simcik: They are what we call ubiquitous, meaning they are everywhere.

TPO: What are the potential health impacts of these substances?

Simcik: That is not my area of study, but not many effects have been found in workers exposed to the manufacture of these compounds. Many studies have linked PFAS to cancer, decreased efficacy of vaccines and attention deficit hyperactivity disorder. My greatest health concern is on developing fetuses. We know these compounds affect the lipid levels in our blood. Lipids are very important in fetal development.

TPO: Describe the concerns that wastewater and biosolids operations have or should have about these substances.

Simcik: These compounds are not as hydrophobic as contaminants operators may be used to, such as PCBs (polychlorinated biphenyls). In other words, they don’t stick to particles. They like to go back and forth between the dissolved and particulate phases. The greatest issue with biosolids is land application. These compounds have been shown to accumulate in crops grown on fields where biosolids have been applied. Another concern is leaching to groundwater and ultimately to drinking water.

TPO: Some states are passing regulations affecting these compounds. Are they warranted?  

Simcik: I think so. These compounds never break down. Anything that persistent is of concern.

TPO: If biosolids are not land-applied, what is the best way to manage the material?

Simcik: Landfills are not the answer because the compounds end up in the leachate, and that can no longer be spread on land or stored in basins. It has to be re-treated at a wastewater plant, and nobody wants that. Incinerators may be a good solution. We often refer to these compounds as chemical rebar because they don’t break down. Successful destruction is temperature dependent.

TPO: Since there are very few incinerators still operating and if landfills are not the best solution, how can land application be made safer?

Simcik: We’ve been working on remediation techniques that we’re going to try applying to wastewater treatment. We’re collaborating with the Metropolitan Wastewater Treatment Plant in St. Paul, adding cationic polymers as coagulants to see if we can get the compounds to stick to the solids phase. We’re using a slip stream, adding polymer coagulants before the final clarifiers. The goal is to eliminate the compounds from the effluent and drive them into the sludge, where they will be irreversibly bound and not available for uptake.

TPO: Do you have any indications of results?

Simcik: We’re still a long ways from understanding the issue. When you work with PFCs, you find out that they’re really weird. They can come down and then they can burp back up. Our next step will be to add the polymer to the activated sludge basin ahead of the final clarifier and see if the coagulants will bind with the PFAS and end up in the sludge. It appears from our lab work that we may be able to make them irreversibly bound to the biosolids and not available for leaching or uptake.

TPO: What is your expectation for future developments?

Simcik: Because municipal wastewater treatment plants are a bottleneck in the distribution of these compounds, they are one of the best places to remove them from circulation. We can’t eliminate them from the broader environment. If we can drive them into biosolids and keep them from becoming available to plants or groundwater, that would be the best of both worlds. The ultimate goal is to destroy them, but that is very difficult. Saving that, the next best thing is to tie them up where they can’t do any harm.

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WEF comments on PFAS and biosolids

The Water Environment Federation issued a statement in May about concerns related to PFAS and land application of biosolids.

“For the past several years, concerns about PFAS (per- and polyfluoroalkyl substances) have been a high-profile issue for the water sector, media and public. PFAS are a group of man-made chemicals that includes PFOA, PFOS and GenX. PFAS have been manufactured and used in a variety of industries, and although they have been phased out for many applications, they are still persistent in the environment. There is evidence that exposure to PFAS can lead to adverse human health effects, although much more research is needed.

“Concerns about PFAS have primarily focused on its presence in drinking water. However, some attention is turning to biosolids. There are rare cases where heavy industrial discharges of PFAS have impacted biosolids, and state environmental agencies are beginning to evaluate regulations for biosolids. WEF wants its members to be aware of these concerns, know that WEF is being proactive, and utilize facts and science-based communications resources as needed.”

WEF’s position

Biosolids production recovers valuable nutrients, organic matter and energy from treated wastewater — it is a safe and innovative process that lowers costs for consumers, improves our environment, conserves natural resources and supports our nation’s agricultural communities.

WEF is closely following concerns about PFAS and continuing to rely on the current science to inform its response. That science shows no significant health risk from human exposure to biosolids and that contamination of surface water or groundwater from biosolids is very unlikely. WEF urges federal and state regulators to focus on stopping these chemicals at their source through appropriate controls on industrial and other uses — before they enter the sewer system or the environment — and to consider the impacts of new policies or laws on utilities. WEF is committed to understanding more about PFAS and supports further research.

WEF is working closely with the National Association of Clean Water Agencies, The Water Research Foundation, WEF Member Associations and regional biosolids organizations to track concerns, provide facts and science, and support an appropriate regulatory response. WEF is also in communication with the U.S. EPA about biosolids.

WEF plans to continue to expand biosolids advocacy, communications, and research, and offering more resources for the water sector. For more information, contact Patrick Dube, biosolids program manager, at pdube@wef.org or Travis Loop, senior director of Communications and Public Outreach, at tloop@wef.org; or visit www.wef.org and search “PFAS.”