According to the Environmental Protection Agency (EPA), the most common use of biosolids is land application, accounting for 51% of utilization and disposal from publicly owned treatment works. With mounting studies showing per- and polyfluoroalkyl substances (PFAS) in biosolids, the practice of land application is under increased scrutiny pending technological and regulatory advancements.
A Brief Interlude on PFAS and the Challenges They Introduce
PFAS chemicals are stable and persistent in the environment, meaning they do not readily degrade and can accumulate in media. As more industries sample for PFAS, there is a growing awareness of just how prevalent PFAS are.
Regulatory and technological landscapes around PFAS are ever-shifting as more is learned about this contaminant of emerging concern. Trihydro has remained at the forefront of digging into the latest PFAS understandings for its clients—read more about the “PFAS problem” here, and catch up on recent happenings here (EPA’s New PFAS Health Advisory Levels) and here (EPA PFAS Strategic Roadmap Updates).
From Source to Sludge to Soil and Groundwater: PFAS Hitches a Ride on Biosolids
The nutrient-rich solids recovered from wastewater treatment plants (WWTPs), once treated and processed to meet the biosolids criteria for chemical/microbiological safety (Code of Federal Regulations (CFR), Title 40, Part 503), are used as soil supplements to improve texture, humidity, and crop yield. Such use of biosolids has the added benefit of reducing the amount of waste that requires disposal in landfills.
However, there are worries that PFAS may end up in biosolids at levels of concern to human health and the environment. PFAS, with their numerous industrial and consumer uses, can end up in WWTPs, whose treatment systems are not generally designed to remove or destroy them. Given their propensity to adsorb to organic matter and particles, PFAS can accumulate in WWTP sludges and carry over to finished biosolids.
Land applied areas may contain PFAS in groundwater since these chemicals can be leached from biosolids via irrigation and rain. Evidence of PFAS in biosolids is triggering some state agencies to issue food consumption advisories, biosolids-specific guidance, and even land application bans.
Is Produce Grown with Biosolids Safe to Eat?
Biosolids are regulated for chemical safety, though PFAS have not yet been added to corresponding regulations. Current federal law (CFR 40, Part 503) requires that biosolids be free of chemicals, metals, and viruses and bacteria that cause illnesses.
While there are instances of PFAS detection in beef and dairy via land-applied biosolids, the U.S. Food and Drug Administration’s (FDA’s) food testing for PFAS suggests detections below levels of concern, with the potential exception of specific seafood from overseas suppliers. However, until EPA establishes final rules on PFAS, the jury is out on where the final limits will land in terms of protection of human health and the environment. Within the current regulatory void, states are taking it upon themselves to establish their own limits.
Are Biosolids Suitable for My Land?
It depends. There are specific requirements and precautions based on the intended use. If applied to non-food growing areas, the magnitude of potential risks is lower than if applied to pastures, crops, and gardens intended for livestock grazing and human consumption. The latter uses may require extra vigilance and/or completion of a site-specific risk assessment.
What to Do with Tainted Biosolids?
If biosolids exceed the PFAS permissible limits determined by an agency, specific permit, or risk assessment, options may be limited for their disposal and management. Hazardous waste landfilling and incineration could be employed—though, landfilling can be expensive, and incineration needs to completely destroy PFAS to avoid air pollution problems.
Because biosolids potentially tainted with PFAS present a considerable challenge, many agencies are looking into source identification and reduction as a best management practice to prevent PFAS from getting into WWTPs in the first place rather than devising technologies to treat PFAS at the plants.
What’s Next?
The most eagerly awaited event on the horizon is the release of EPA’s risk assessment on PFAS in biosolids. Using the 40CFR503 and PFAS Strategic Roadmap framework, EPA is working to understand PFAS WWTP sources, occurrence and concentrations in biosolids, use/disposal pathways for human and ecological receptors, toxicity, food chain accumulation, and screening methodologies/models. The outcome of the risk assessment will form the basis for EPA to develop numerical limits, performance/equipment standards, and/or best management practices falling under Part 503 compliance. Draft risk assessment findings are expected in fall 2022. We will update you when the report is published.
Need to Know More?
Trihydro is committed to assisting its clients in navigating the PFAS problem and has several years of PFAS project experience to apply toward delivering solutions. If you are experiencing PFAS challenges at your site or just want to know more, connect with us using the form linked below.
