Compost

PFAS COMMUNICATIONS

The Oneida County Solid Waste Department has composted wastewater residuals, also known as fiber cake, received from the paper mill in Rhinelander since the mid 1990s.

In September of 2024, as a part of their compost license renewal through the Wisconsin Department of Natural Resources (WDNR), the Solid Waste Department had a sample of finished fiber cake compost analyzed for per and polyfluoroalkyl substances (PFAS).

The concentration results for the combination of two PFAS compounds, PFOA and PFOS, of 212 nanograms per gram (ng/g, or parts per billion), required notification of the Wisconsin Department of Natural Resources (WDNR) as per the Department’s Interim Strategy for Land Application of Biosolids and Industrial Sludges Containing PFAS. (See: https://dnr.wisconsin.gov/sites/default/files/topic/PFAS/PFAS BiosolidslnterimStrategy.pdf)

In conjunction with that notification, the Solid Waste Department suspended sale and use of fiber cake compost.

The Solid Waste Department is working with the WDNR to determine a path forward for fiber cake and fiber cake compost handled by the Solid Waste Department.

Additional information regarding PFAS, from the Wisconsin Department of Health Services can be found here: PFAS and Backyard Gardening.

Additional information from the United States Environmental Protection Agency (USEPA), can be found here: Per- and Polyfluoroalkyl Substances (PFAS) I US EPA.