PFAS, often called “forever chemicals,” are found throughout the environment, and—as the nickname suggests—they are extraordinarily difficult to destroy because of their strong chemical bonds, which allow them to persist in soil, groundwater, and other parts of the environment.

Researchers have tried a range of approaches to eradicate PFAS contamination, from filtering and capturing the chemicals to using intense heat, pressure, or electricity to destroy them, with varying degrees of success and generally lack comprehensive evaluation of byproducts and a full accounting of residual organofluorine. One particularly stubborn challenge is what to do when PFAS end up in biosolids—the nutrient-rich organic materials left over from the wastewater treatment process that can be used as fertilizer on agricultural land. While biosolids can be a valuable agricultural resource, the presence of PFAS often prohibits their reuse potential or inadvertently introduces the persistent chemicals into soil and the surrounding environment.

Now, University of Minnesota School of Public Health (SPH) researchers in collaboration with College of Food, Agricultural and Natural Resource Sciences (CFANS), Environmental Decontamination Limited (EDL) and EA Engineering, Science, and Technology, Inc., PBC (EA) will test an innovative technology designed to destroy PFAS while preserving the agricultural value of biosolids.

Led by SPH Professor Matt Simcik and CFANS Professor Carl Rosen, researchers will evaluate a process known as mechanochemical destruction (MCD), which uses EDL’s proprietary high-speed ball mill filled with thousands of small, metal balls that repeatedly collide with and grind the biosolids. Those collisions create intense mechanical forces that facilitate chemical reactions capable of destroying PFAS. The researchers will test different treatment times and potential co-milling agents to determine which conditions are most effective at destroying PFAS while maintaining the potential for agricultural reuse and will use state–of-the-art methods to evaluate the full fluorine mass balance.

Specifically, the team will measure how effectively the process destroys PFAS and whether any organofluorine chemicals remain after treatment. Researchers will also examine whether the treated biosolids retain their agricultural value in greenhouse studies and compare the environmental impact of the technology with current approaches to managing biosolids.

If successful, the project could provide wastewater utilities with a new option for managing PFAS as regulatory scrutiny increases and long-term options for handling contaminated biosolids become more limited.

This project is being funded by the Legislative and Citizens Commission on Minnesota Resources (LCCMR). The funding totals $799,000.