The 2023-2024 Minnesota Legislature directed the MPCA to develop and implement a strategy to test for per- and polyfluoroalkyl substances (PFAS) in biosolids that are applied to land. The goal of Minnesota’s biosolids PFAS strategy is to ensure protection of human health while retaining the benefits of biosolids applied to land.
Informational webinar
The MPCA held an information session in November about our draft strategy for PFAS in biosolids from wastewater treatment facilities that are applied to land.
Background
Municipal wastewater treatment facilities treat wastewater that can contain PFAS from industries, commercial businesses, and homes. Biosolids are nutrient-rich organic materials generated during the treatment of domestic sewage at wastewater treatment facilities. Because biosolids are a byproduct of treating wastewater that contains PFAS, biosolids may contain PFAS. When applied to land, PFAS in biosolids have the potential to move in the landscape due to precipitation and other environmental factors. PFAS at high levels in biosolids could potentially contaminate soils, surface water and groundwater, and/or be absorbed by crops.
Applying biosolids to land has many benefits that include providing organic matter and macro- and micronutrients to soil, carbon sequestration, providing an economical way to manage biosolids, and conserving landfill space. About 20 percent of the biosolids generated in Minnesota are applied to land, mostly to agricultural lands but also for reclamation of lands used for mining. Biosolids are applied to less than 0.1 percent of land that grows crops in Minnesota.
Ongoing research by the MPCA, the U.S. Environmental Protection Agency, and others seeks to understand the potential risk to human health and the environment. That research includes understanding the amounts of PFAS in biosolids and the potential impact to people and the environment.
There is currently no human health standard for PFAS in biosolids, but the EPA is expected to publish a biosolids risk assessment in December 2024.
We expect that most biosolids will have low amounts of PFAS. However, in other states where biosolids have been tested for PFAS, only a small number of samples showed elevated levels. The high levels were due to discharges from an industry that used PFAS in its process. In these cases, reducing the source of PFAS from the industry lowered the amount of PFAS in the biosolids. Testing biosolids for PFAS is foundational because identifying the types and amounts of PFAS in biosolids is key to understanding the potential risk to human or environmental health.
Testing also helps identify the sources of PFAS in biosolids and measure the effectiveness of actions to reduce PFAS in biosolids, while sampling informs decisions about how to manage biosolids.
Proposed biosolids strategy
The draft biosolids strategy applies to all wastewater treatment facilities that intend to apply biosolids to land and includes sampling and response actions based on sample results. The strategy is designed to complement other requirements applicable to managing biosolids and ongoing efforts to reduce PFAS in municipal wastewater.
This proposal mirrors efforts in other nearby states. The strategy will be implemented until the EPA issues risk-based limits for PFAS in biosolids that are applied to land.
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Share feedback and stay engaged
The MPCA is gathering feedback on this draft strategy. Please submit your feedback through the MPCA’s SmartComment page.
