Wastewater Treatment Plants / Industrial Pretreatment Program
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) is responsible for protecting the public health and the environment by regulating discharges of wastewater to Michigan’s surface waters. Anyone discharging wastewater into the surface waters of the state is required by law to obtain a National Pollutant Discharge Elimination System (NPDES) permit. The NPDES program regulates municipalities and industries that discharge directly into lakes and streams by limiting pollutants and requiring other protections.
As a special effort under the NPDES program, the MDEQ launched the Industrial Pretreatment Program (IPP) Per- and Polyfluoroalkyl Substances (PFAS) Initiative in February 2018. This initiative aims to reduce and eliminate certain PFAS from industrial sources that may pass through municipal wastewater treatment plants (WWTP) and enter our lakes and streams, potentially causing fish consumption advisories or polluting public drinking water supplies.
Wastewater Discharged Directly into Lakes and Streams
EGLE’s Water Resources Division (WRD) has added PFAS sampling into routine NPDES permit compliance sampling inspections to further understand the prevalence of PFAS in wastewaters of Michigan. In 2017 wastewater was sampled at six municipal WWTPs. In 2018, PFAS samples have been collected from over 25 permitted NPDES dischargers as of the end of August 2018.
Industrial Discharges to Wastewater Treatment Plants
Many industries discharge to municipal WWTPs rather than discharge directly to surface waters. Municipal WWTPs often regulate their industrial users through an IPP required by their NPDES permit. The IPPs provide the basis for WWTPs to regulate industries so industrial pollutants do not interfere with treatment processes or pass through to our lakes and streams. IPPs may require industries to pretreat wastewater or otherwise reduce or eliminate harmful pollutants. The IPP is a federally-mandated program and a core part of the federal Clean Water Act. For more information about IPP, see Michigan's Industrial Pretreatment Program web page.
Michigan has water quality standards (WQS or Michigan Rule 57 values) for two PFAS, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). PFOS has led to fish consumption advisories for some Michigan rivers because it bioaccumulates so readily in fish and has potential human health effects if eaten. The applicable WQS for PFOS is very low at 12 ppt (parts per trillion, equal to nanograms per liter) for streams that are not used for drinking water and 11 ppt for those that are used as a drinking water source. The applicable WQS for PFOA is much higher at 12,000 ppt for surface waters that are not used for drinking water and 420 ppt for those used as a drinking water source.
In February 2018 EGLE launched the IPP PFAS Initiative, requiring all municipal WWTPs with required IPPs (93 statewide) to find out whether they may be passing through PFOS and/or PFOA to surface waters and reduce and eliminate any sources if found. Additional actions may be required if WWTP wastewater exceeds WQS. Interim reports were due in June 2018 and summary reports are due in October 2018. Extensions to these deadlines were granted based on the size and complexity of WWTP collection systems and other factors. EGLE is working closely with municipal and industry groups to reduce and eliminate or control sources of PFOS and PFOA as they are found.
For municipal WWTPs, major sources of PFOS and PFOA are thought to include metal finishers, paper manufacturers, and fabric/leather treaters that have used PFAS-containing chemicals as well as those industrial users (such as landfills and centralized waste treaters --link here--) that may have accepted wastes from these sources. Although chemical manufacturers in the United States voluntarily stopped making PFOS and PFOA years ago, these chemicals may still be manufactured in other countries and imported. These persistent chemicals may also be found in factories years after they were used. Sites contaminated by firefighting foams or PFAS-contaminated industrial wastes may also be sources for WWTPs if they discharge to the sanitary sewer.
Unfortunately, conventional WWTP treatment does not effectively remove PFAS if it is discharged to the sewer system by industries or contaminated sites. Instead, PFAS may be passed through treatment to lakes, streams, and groundwater as well as interfere with management of solids from the treatment process referred to as sludge or biosolids.