The Madison Metropolitan Sewerage District’s first sampling to analyze PFAS in local wastewater has revealed acceptable levels of the manmade compound, the district has announced.

PFAS, or per-and polyfluoroalkyl substances, have been in use for more than 70 years and are found in a wide range of products such as food packaging, nonstick cookware and carpeting. Persistent exposure to high levels of PFAS has been shown to impact human health. As the Wisconsin Department of Natural Resources (DNR) continues work on a statewide action plan for PFAS, the Madison Metropolitan Sewerage District has tested samplings in accordance with its PFAS action plan developed in 2019.

“The District plays a vital role in helping protect our region’s valuable water resources,” said Michael Mucha, in an announcement of the test results. “Our PFAS sampling plan demonstrates our holistic, proactive approach to understanding and addressing emerging contaminants, even though we aren’t yet regulated for them. While the results of our initial sampling are favorable, they are just the first step in our investigation to ensure we remain good stewards of public health and the environment.”

Part of the district’s PFAS action plan called for identifying any knowledge gaps regarding how PFAS move through the plant. The sampling and analysis was prepared to aid in that goal.

The first phase of the plan tested for 33 PFAS compounds, as outlined by the DNR. The district’s influent (incoming wastewater), treated effluent (outgoing wastewater) and biosolids were tested.

The District’s consultant, TRC, collected the samples and Eurofins Test America, certified by the DNR to conduct PFAS testing, analyzed the samples. The testing showed:

- PFAS types consistent with results from other municipal wastewater treatment plants in urbanized areas without significant industrial sources. The District tested influent from the five large sewer pipes, which aggregate wastewater from the service area and deliver it to the plant. The combined influent concentration of PFOA is 5.13 ppt (parts per thousand) and PFOS is 6.86 ppt. By comparison, the influent median concentration from 42 wastewater treatment plants is 4.6 ppt for PFOA and 7.5 ppt for PFOS.

- PFAS in the district’s treated effluent are lower than the currently proposed Wisconsin regulatory standards. Testing revealed a range of 9.7 to 11 ppt of PFOA in the District’s effluent. The DNR’s proposed Surface Water Standard for Public Water is 20 ppt. For PFOS, the district’s effluent is 3.7 ppt; the proposed standard for surface waters is 8 ppt.

-PFAS in biosolids were similar to data from other municipal wastewater treatments plants, that, like Madison’s, do not accept industrial waste from major PFAS sources.

More results can be found at the website dedicated to the District’s PFAS research at www.madsewerpfasinitiative.org.

The district’s next testing phase will include sampling to examine processes within the plant that may add or transform PFAS compounds, a deeper dive into PFAS in the district’s biosolids and further testing to determine if certain areas of the collection system contribute more PFAS than other areas.

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