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PFAS in biosolids

A large machine called a TerraGator driving through a farm field, spraying biosolids directly on the ground through 6 hoses on the back
Environment, Great Lakes, and Energy

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.

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

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).

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

Concentrations of PFOS & PFOA at all tested facilities

Year PFOS (ppb)
mean
PFOS (ppb)
median
PFOA (ppb)
mean
PFOA (ppb)
median
2018* 184 13 25 7
2021 21 9 8 4
2022 16 10 7 3
2023 11 7 6 3
2024 8 5 5 2
*includes data from industrially impacted facilities as part of a statewide study

Contact us

Christian Smith, Statewide PFAS in Biosolids Coordinator, at SmithC186@Michigan.gov or 517-257-0251.