Wastewater Treatment Plants / Industrial Pretreatment Program

Surface waters are lakes,
streams, wetlands, county
drains, or roadside ditches
that drain to lakes, streams,
etc.
Groundwater is water below
the land surface

Diagram of PFAS Water Cycle

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. 

EGLE is undertaking several efforts to address PFAS in surface waters, including monitoring municipal and industrial discharges, implementing the Industrial Pretreatment Program (IPP) PFAS Initiative, and monitoring lakes and streams.

Learn more about EGLE's PFAS sampling of lakes and streams.

 

WASTEWATER DISCHARGED DIRECTLY INTO LAKES, STREAMS, AND GROUNDWATER

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.  Since 2017, EGLE has sampled 56 municipal Wastewater Treatment Plants (WWTPs) and 41 industrial dischargers (industries including airports, landfills, paper plants, and groundwater clean-up sites for other contaminants) for a total of 161 samples collected.

Industrial Discharges to Wastewater Treatment Plants

Many industries discharge to municipal WWTPs rather than discharge directly to surface waters or groundwater. Municipal WWTPs often regulate their industrial users through the IPP required by their NPDES or Groundwater Discharge 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, streams, and groundwater. 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. 

Municipal WWTPs major sources of PFOS and PFOA come from industries that have used PFAS-containing chemicals (such as chrome platers and paper manufacturers) and industrial users that may have accepted wastes that used PFAS-containing chemicals in their processes and/or products (such as landfills and centralized waste treaters).  Although chemical manufacturers in the United States voluntarily stopped making PFOS and PFOA years ago, these persistent chemicals may be found in factories years after they were used.  Sites contaminated by firefighting foams or PFAS-contaminated industrial wastes have also been found to be sources for WWTPs when 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.

Michigan has water quality values (WQV or Michigan Rule 57 values) for discharges to surface waters 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 Michigan Rule 57 values apply to NPDES discharges.  

 

Compound

WQV* (ng/L)

Established Date

PFOA (Drinking Water Source)

 420 May 2011
PFOA 12,000 May 2011
PFOS (Drinking Water Source) 11 Mar 2014

PFOS

 12 Mar 2014

 

Michigan has generic cleanup criteria for groundwater used as drinking water (Part 201 Rule 44) for seven PFAS as listed in the table below. Municipal WWTPs that discharge to groundwater are subject to the Part 201 Rule 44 criteria.  

PFAS

Generic Cleanup Criteria (ppt)
Perfluorooctanesulfonic acid (PFOS) 16
Perfluorooctanoic acid (PFOA) 8
Perfluorononanoic acid (PFNA) 6
Perfluorohexane sulfonic acid (PFHxS) 51
Perfluorohexanoic acid (PFHxA) 400,000
Perfluorobutane sulfonic acid (PFBS) 420
Hexafluoropropylene oxide dimer acid (HFPO-DA or GenX) 370

 


Michigan's IPP PFAS Initiative

In order to address the potential that municipal WWTPs could be passing through elevated levels of PFAS through their treatment systems to lakes, streams, and groundwater, EGLE launched the IPP PFAS Initiative in February 2018.

The IPP PFAS Initiative required all municipal WWTPs with required IPPs (95 statewide) to find out if they were passing through PFOS and/or PFOA to surface waters or groundwater and, if found, to reduce and eliminate any sources.  Under the Initiative, WWTPs were required to:

  • Identify industrial users to their system that were potential sources of PFAS.
  • Sample probable sources and their WWTP discharge (effluent) if sources were above screening criteria (12 ppt PFOS).
  • Require source reduction at confirmed sources.  This is being accomplished through pollutant minimization plans, equipment/tank change out/clean outs, product replacement, and installation of pretreatment to remove PFAS, specifically PFOS, prior to discharge.
  • Monitor compliance of  confirmed sources  and ensure that they meet local IPP PFAS requirements.
  • Submit required reports and monitoring results as required by the WRD.

As a part of this effort, theWRD developed numerous documents, including Frequently Asked Questions (FAQs), Wastewater PFAS Sampling Guidance, and Recommended PFAS Screening and Evaluation Guidance. 

IPP PFAS Initiative Status - February 2018 through March 2021

Since implementation, significant progress has been made in identifying sources of PFAS, specifically PFOS, to WWTPs and reducing levels released to the environment. In December 2020, two additional WWTPs were added to the Initiative bringing the total to 97 WWTPs statewide with IPPs.

 Key observations the WRD has made to date (March 2021):

  • Sixty-six (66) of 97 of WWTPs with IPPs (or 68%) either have no sources or have sources but have discharges at or less than the PFOS WQS.
  • 93 out of the original 95 WWTPs were able to complete the initial screening of their industrial users within one year of starting the Initiative.  Most were able to complete the screening within 6 months.
  • Low levels of PFOS (approximately 3 ppt - 7 ppt) were detected in wastewater even when no significant industrial sources were present.  This suggests that background levels of PFAS may be found in most communities.
  • Source reduction efforts have resulted in substantial drops in PFOS concentrations being discharged at the WWTPs.  (See Table 1)
Table 1. Substantial PFOS Reduction at WWTPs with Exceedances
Municipal WWTP PFOS, Effluent (ppt, as of March 2021) PFOS Reduction in Effluent (highest to most recent) Actions Taken to Reduce PFOS
Ionia < 5.08 99% Treatment (GAC) at source (1)
Lapeer 8.2 99% Treatment (GAC) at source (1)
Wixom 16* 99% Treatment (GAC) at source (1)
Howell 3.8 97% Treatment (GAC/resin) at source (1)
Bronson 2.2 99% Treatment (GAC) at source (1)
Kalamazoo 4.84 90% Treatment (GAC) at source (2), change water supply
K.I. Sawyer 5.4 98% Eliminated leak PFOS-containing fire-fighting foam
GLWA (Detroit) 12* 68% Treatment (GAC) at sources (17)
Belding 9.4 33% Restricted landfill leachate quanitity accepted
Port Huron 12* 99% Elimination of PFAS source (2)

*Effluent exceeds WQS

Monitoring results, if applicable, are provided for each WWTP that participated in the IPP PFAS Initiative in the interactive map below.  Additional information for each WWTP can be found in the MiWaters Site Map Explorer at Michigan.gov/MiWaters.

View the Michigan IPP WWTP PFAS Status interactive map

This application contains a complex map. Call 517-388-0267 for assistance with reading or interpreting. If you have questions or comments, please contact Brian Zuber at ZuberB@Michigan.gov.

Statewide PFAS Assessment of WWTPs and Biosolids/Sludge

In 2018, ELGE implemented two initiatives to assess potential environmental impacts of PFAS associated with municipal wastewater. The first initiative, the IPP PFAS Initiative, was launched in February 2018.  As described above, the purpose of the IPP PFAS Initiative was to evaluate the potential for PFAS from industrial sources to pass through WWTPs to receiving waters (groundwater, lakes, and streams), and to reduce or eliminate significant industrial sources of PFAS to the municipal system. 

EGLE launched a second initiative in the fall of 2018. Under this initiative, a statewide PFAS assessment of 42 WWTPs was conducted to better understand the fate of PFOS and PFOA at municipal WWTPs. Influent, effluent and biosolids/sludge sampling was performed to calculate mass balances for PFOS and PFOA through municipal wastewater treatment processes. The 20 largest WWTPs with the highest flows, along with an additional 22 WWTPs with various treatment processes, were selected. A total of 29 agricultural fields associated with 9 WWTPs were also evaluated for potential PFAS impacts utilizing soil, surface water, tile drains, and groundwater samples. This statewide PFAS sampling study provides a robust evaluation of potential PFAS impacts to the WWTPs and biosolids from Michigan.

Identified Industrial Sources of PFOS to Municipal WWTPs (Report): The Wastewater Workgroup summarized the industrial sources of PFOS to municipal wastewater treatment plants (WWTPs) that were identified through the IPP PFAS Initiative.  Sources are defined as those industrial users with discharges to WWTPs greater than 12 ppt, which was used as screening level.  The majority of significant PFOS sources were metal finishers with a history of fume suppressant use, contaminated sites associated with industries or activities with PFOS usage, and landfills that accepted industrial wastes containing PFOS. 

NPDES PFAS Permitting Strategy

Moving forward, the Wastewater Workgroup has developed a Municipal NPDES Permitting Strategy for PFOS and PFOA. The goal of the strategy is to continue to identify, reduce, and remove PFOS and PFOA at WWTPs. 

The Wastewater Workgroup developed an Industrial Direct Discharger and Industrial Storm Water Compliance Strategy for addressing PFOS and PFOA discharges from industrial direct and industrial storm water discharges.  The goal of the strategy is to reduce or eliminate PFOS and PFOA from industrial facilities holding NPDES and Groundwater Discharge permits to meet applicable criteria.  

Updated: June 9, 2021