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Sewage Treatment Plant

Emerging Contaminants of Concern for Wastewater Treatment Plants

Wastewater Treatment Plants (WWTP) have many concerns and obligations to meet legal and moral obligations to the public. Western States Alliance (WSA), a project of the Pollution Prevention Resource Center, is dedicated to providing information, best management practices, technical assistance, and training specifically around Fats, Oils, and Grease (FOG). Many WWTPs don’t know the true impact of FOG on their infrastructure nor the costs associated with keeping it from building up and causing sanitary sewer overflows and other problems, nor the cost of treating FOG at the WWTP. That is why WSA was created and continues to be dedicated to this issue.

As a result of years of training across the country, WSA has learned of the concern about other emerging contaminants and some training materials on these other contaminants is now included in WSA FOG training.

Purpose of training on Contaminants of Emerging Concern (CEC) and PFAS

1. Awareness - We want to raise awareness of current and future (likely) contaminants that may not be regulated yet but are of concern and help you understand their potential impacts on human health, the environment, and your water treatment operations. Know the issues so you can balance the complex task of reassurance that you're taking the situation seriously with the reassurance that there is probably nothing to worry about.

2. Sources – many of the likely sources of these contaminants are non-point sources or other sources that are not currently regulated by pretreatment programs.


3. Prevention - We want you to be aware of prevention strategies – these are the most cost-effective ways to deal with contaminants, but they require a different approach than you may currently use with industrial sources, including public outreach.


4. Partnerships - Know the partnerships that you can become part of and/or ones that you may need to foster in your community.


5. Mitigation - Learn mitigation strategies that other programs use.

Contaminants of Emerging Concern

Contaminants of emerging concern are chemicals and toxics found in waterbodies that may cause ecological or human health impacts and they are not currently regulated.​ Treatment plants cannot always remove these contaminants.​

The emerging contaminants may demonstrate low acute toxicity but cause significant reproductive effects at very low levels of exposure. The effects of exposure to aquatic organisms during early stages of life may not be observed until adulthood. Therefore, traditional toxicity test endpoints may not be sufficiently comprehensive for criteria derivation for these chemicals. Additionally, only certain types of aquatic animals may be affected (e.g., fish or vertebrates)

Endocrine Disrupters


Endocrine disruptors are chemicals that interfere with the endocrine system ( a system of glands that produces all the hormones used by the body, including testosterone, estrogen, insulin, and adrenaline). These disruptors can alter the normal functions of hormones resulting in a variety of health effects.. They can alter hormone levels leading to reproductive effects in aquatic organisms.

  • Bisphenols (BPA). A chemical compound primarily used in the manufacturing of various plastics.

  • Phthalates. Used to create flexibility in plastics, used as additives in cosmetics, and personal care products, many states have water quality criteria limiting phthalates.

  • Triclosan is an antimicrobial. It is now banned for use in over-the-counter soaps and body washes, but legacy products exist.

  • Some pharmaceuticals

  • Some personal care products ​




A pesticide is any substance or mixture of substances intended for​:

  • Preventing, destroying, repelling or mitigating any pest.​

  • Use as a plant regulator, defoliant, or desiccant.​

  • Use as a nitrogen stabilizer​


Sources of pesticides include current use pesticides - herbicides, insecticides, and fungicides and legacy pesticides – chlorinated insecticides banned in the U.S. and many other countries. Many continue to be used in parts of the world.​


Point sources are regulated, i.e., manufactures, landfills, agriculture, illegal/improper disposal and POTWs​.


Flea and Tick products have been shown to be significant contributors to pesticide pollution in the San Francisco bay. They contain:

  • Pyrethroids (Bifenthrin, Deltamethrin, and permethrin) – some flea shampoos, ​

  • Fipronil - Frontline spot treatment and generic, and ​

  • Imidacloprid – Advantage spot treatment and generic.​

Nonpoint Sources contribute more contaminants than point sources – lawn and garden, landscaper, vegetation management by roads departments and utilities. The presence of pesticides in stormwater is greater than in wastewater.​

Impacts to Health and Environment:

  • Acute & Chronic human effects, ​

  • generational/cumulative health impacts and​

  • degradation of water bodies-drinking water sources​

Per- and polyfluoroalkyl substances (PFAS)


The diagram at right shows some of the chemical compounds lumped together as "PFAS".​  PFAS were first used commercially in the 1940s. Polytetrafluoroethylene (PTFE), along with C8/PFOA, were used to produce Teflon​.


Although manufacturers have phased out their use in Canada and the U.S. over the past two decades, they remain ubiquitous in the environment—and in our bodies. ​

(Image Source: ATDSR, )



(Image Source: West Virginia Water Authority)

Some common sources of PFAS that are of concern include:

  • Commercial car washes

  • Platers/metal finishers

  • Paper and packaging manufacturers

  • Tanneries and leather/fabric/carpet treaters

  • Manufacturers of parts with Polytetraflurorethylene (PTFE) or Teflon type coatings (e.g., bearings)

  • Landfill leachate

  • Centralized waste treaters

  • Known or suspected PFAS contaminated sites

  • Fire fighting training facilities

  • Airports


(Image Source: Michigan Department of Environment,

In the diagram above, sources of PFAS are shown in boxes and exposure pathways are shown in the ovals. One of the difficulties with PFAS is they’re mobile between groundwater and surface water.​

​What is EPA doing to address PFAS?


EPA has a strategic roadmap to address PFAS. It includes addressing PFAS levels via Clean Water Act permitting, work to improve analytical methods, development of water quality criteria and fish advisories, effluent guidelines, and funding.


  • EPA’s Plan 15 provides industrial effluent limitation guidelines and pretreatment standards (ELG) for Organic chemicals and plastic manufacturing, electroplating and metal finishing, and landfills.

  • EPA is proposing a POTW PFAS study to identify categories of IUs discharging wastewater contaminated with PFAS, collect data on PFAS concentrations in domestic wastewater influent to POTWs, characterize PFAS currently being discharged from IUs and domestic sources, collect data on absorbable organic fluorine (AOF) concentrations in wastewater, and better understand PFAS pass-through in POTWs to biosolids and effluent. POTWs may have to pay the participation expenses themselves. There is money in the Bipartisan Infrastructure Law for potential funding.

  • EPA provided NPDES Permit Direction to States on PFAS via a December 2022 Memo. It recommends quarterly PFAS monitoring at POTWs and industries, pretreatment actions including Industrial User Inventory to includes categories expected to discharge PFAS, development of BMPs that focus on pollution prevention (source reduction) and including fire-fighting foams in stormwater permits.

What are typical best management practices?


Various options to deal with PFAS and other pollutants is pollution prevention (P2). The P2 Act of 1990 defined P2 as source reduction, basically not producing or generating them. The waste management hierarchy shown in the diagram at right shows the preferred strategies to deal with pollutants, including PFAS. After source reduction is reuse/recycling followed by treatment and disposal.

Prevention is preferred over the other options and will cost less. The further down you go on the hierarchy, the more it costs to deal with.

Pollution Prevention Heirarchy (1).png

PFAS – Typical Best Management Practices

  1. Product Elimination and Substitution

  2. Use PFAS-containing aqueous film-forming foam (AFFF) in emergencies only (drill for fire events with non-PFAS foam)

  3. Clean and decontaminate equipment, collecting all effluent for treatment.

  4. Replace equipment with non-PFAS containing equipment

  5. Practice good housekeeping and spill prevention

What are other states doing?

Michigan has an Industrial Pretreatment Initiative that began in 2018. It required 99 WWTPs to screen Industrial Users (IUs), evaluate those with potential to be sources of PFAS, follow-up sampling, sample WWTP effluent if IUs exceed 12 ppt PFOS, and sample WWTP biosolids if effluent is equal to or greater than 50 ppt PFOS.


Michigan found that metal finishing operations and landfills constitute the majority of  PFOS discharges to WWTPs. In Michigan, WWTPs without significant industrial sources met the water quality standards, leading to the conclusion that general consumer use of products with PFAS coatings and/or ingredients is not a significant source of PFOA to WWTPs


Minnesota produced a report evaluating current alternatives and estimated cost curves for PFAS removal and destruction from municipal wastewater, biosolids, landfill leachate, and compost contact water. Technologies evaluated include:

  • nanofiltration/reverse osmosis (RO)
  • foam fractionation

  • granular active carbon (GAC)

  • reactivated GAC

  • colloidal activated carbon

  • ion exchange resins (single use media)

  • ion exchange resins (regenerable media)

  • modified clay

  • ion exchange resin solvent regeneration



Professional associations of clean water agencies are important partners to keep up with the latest approaches and technologies to preventing and controlling PFAS.



The local health department can be a good partner for source water protection and prevention of other pollutants including pharmaceuticals. Drug and other takeback programs help keep unused pharmaceuticals out of the wastewater or the landfill.​

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