PFAS in biosolids

Current and historical activities that can contribute PFAS to sewage sludge include:

Industrial releases (e.g., certain types of firefighting foam, pulp and paper plants, metal finishing/electroplating plants)
Commercial releases (e.g., car washes, industrial launderers)
Down-the-drain releases from homes (e.g., use of consumer products like after-market water resistant sprays, cosmetics, ski wax, floor finishes, laundering of stain or water-resistant textiles with PFAS coatings).
If products containing PFAS are disposed of at a municipal solid waste landfill, because the most common disposal practice for landfill leachate is to transfer it to a wastewater treatment plant, then the landfill’s leachate could be a source of PFAS to a wastewater treatment plant.

Studies have found PFAS in sewage sludge even at wastewater treatment plants that only receive wastewater from residential and commercial users.

Currently, 28 or more PFAS analytes are analyzed for in biosolids - check MPART's PFAS minimum laboratory analyte list for specifics.

PFAS interim strategy for biosolids

Michigan Farmland Acreage Comparison pie chart showing less than 0.5% total Michigan acres used for biosolids in 2023-2024 and 99.5% total harvested cropland acres in 2022

How much farmland in Michigan receives biosolids?

The percentage of acres used for biosolids is less than a half of a percent of the total acres of harvested cropland in the state.

This pie chart shows the total Michigan harvested cropland acres reported in 2022 from United States Department of Agriculture (USDA) compared to the total acres in Michigan utilized for biosolids land application (as reported in the biosolids annual reports from October 2023 to September 2024).

What EGLE is doing

EGLE implemented the Land Application of Biosolids Containing PFAS Interim Strategy first in 2021, with subsequent modifications in 2022 and 2024. The goal of this strategy was to continue source reduction efforts, prohibit land application of industrially impacted biosolids, mitigate risks moving forward, and to inform the generators and farmers/landowners about PFAS in biosolids. This strategy put in place thresholds for how biosolids may be land applied (along with other requirements for the generator) based on concentrations of PFOS and PFOA with the 2024 update.

All facilities that land apply Class A or Class B biosolids are required to collect one representative sample of the finished biosolids product per calendar year prior to land application. Facilities with biosolids designated as Exceptional Quality are required to collect quarterly samples of the finished biosolids product.

Facilities are required to take certain actions depending on the tier / threshold for PFOS and PFOA concentration in parts per billion (ppb).

2024 Interim Strategy Results showing 89% facilities below 20 ppb and 11% facilities between 20 and 100 ppb

Results from the 173 facilities that submitted biosolids PFAS sample results in 2024 show the majority of biosolids produced in Michigan are below 20 ppb for PFOS and/or PFOA. The 11% of facilities with biosolids between 20 and 100 ppb are taking steps to identify the source or sources of PFOS and PFOA and implement a source reduction plan.

Facility requirements

Exceptional Quality
- Combined PFOS and PFOA below 20 ppb
- Sample finished biosolid product quarterly
Below 20ppb
- Notify landowner and/or farmer of PFAS results
Between 20 ppb and 100 ppb
- Notify landowner and/or farmer of PFAS results
- Reduce application rate to a maximum of 1.5 dry tons per acre or submit alternative risk mitigation strategy
- Sample facility discharge within 30 days
- Implement a source reduction plan
Greater than 100 ppb (industrially impacted)
- Land application prohibited
- Sample facility discharge within 30 days
- Implement a source reduction plan