PFAS contamination in Michigan septage
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EmailThe most effective way to reduce PFAS from wastewater entering our ground water, surface water or crops is to eliminate their usage whenever possible.
What is septage?
Septage is the general term for the waste and solids that accumulate in a septic tank and other on-site sewage treatment systems. In rural homes without sewer, waste from flushing the toilet, running the dishwasher, doing the laundry or taking a shower travels through a septic drainpipe and into a large concrete, fiberglass or plastic vessel known as a septic tank. From there, solids sink to the bottom where bacteria break it into a sludge and in most systems, the liquids travel through a system of pipes that leach into a drain field. The septic sludge is then removed from septic tanks every few years by specialized, licensed, tanker trucks.
In some areas of the country where soil conditions do not allow for a drain field, or as a temporary solution, a holding tank is used. A holding tank has no outlet and stores raw wastewater until a pumper removes it. Septage from holding tanks is typically very dilute and will need to be pumped every few weeks or months depending on use.
The term septage can also include waste from portable toilets and other on-site treatment systems. Septage does not include industrial waste or effluent from wastewater treatment plants. Biosolids are the organic materials that remain after the treatment of sewage at wastewater treatment plants and are monitored and regulated under the United States Environmental Protection Agency (EPA) and Michigan’s Department of Environment, Great Lakes and Energy (EGLE), Water Resources Division.
Septage disposal
Septage disposal is controlled at both the state and federal levels. Septage can be disposed of by delivering to a wastewater treatment plant, independent septage treatment facilities or land application. Discharge to a wastewater treatment plant is common practice if nearby municipalities have capacity and treatment infrastructure. Some areas of Michigan have independent septage treatment facilities that handle septage waste outside of traditional municipal systems and utilize some type of treatment technology, such as aerobic digesters, to treat the waste. After treatment at a wastewater treatment plant or septage treatment facility, the resulting biosolids can be land applied, incinerate or landfilled.
In Michigan, septage can be land applied once the site is authorized by EGLE. In permitting a site for land application of septage, the landowner and hauler must follow the rules outlined in the Michigan Legislature Act 451 of 1994 Part 117. Raw septage is not tested by EGLE for environmental contaminants.
Farmers use septage because it provides a cost-effective source of fertilizer for growing crops, increases soil organic matter and supports local economies by recycling nutrients. Considerations for site permitting by EGLE include many factors to ensure public safety and ground and surface water protection, including:
- Land topography (slope)
- Water table depth
- Application rates considering soil nutrient load and crop removal rates of N, P, and K
- Setbacks from surface water, public and private wells, roads, property lines, homes and commercial buildings
- Application method (inject into the soil or surface application)
- Treatment to reduce pathogens
- Vegetation to be grown on the land
PFAS in septage
PFAS, or per- and polyfluoroalkyl substances, are a large group of chemicals (~12,000) sometimes referred to as “forever chemicals” because of the strong fluorine-carbon bond that persists in the environment. PFAS are found in all kinds of household products (e.g. Teflon pans, cosmetics, cleaners, fabric treatments, waxes). A common characteristic of PFAS is that they build up in the environment, animals and people, and can lead to serious health impacts. When consumers utilize products in their home that contain PFAS, they often end up in a septic system or wastewater treatment system through normal daily practices like washing dishes, laundry, showering, toilet use and disposal of cleaning products.
Adverse health effects, such as cancers and immune system disorders, are associated with long-term PFAS exposure. Because of the chemical and toxicological differences among individual PFAS chemicals, there is uncertainty about the exposure level at which adverse effects may occur. To protect human health, further research is needed to understand what acceptable concentrations of PFAS in soil are.
Farmers are not required to test soils for environmental contaminants like PFAS before or after septage application because there are no guidelines or thresholds to regulate by. The scientific knowledge of how PFAS move from soil to water and/or into plants is limited. We know that septage will contain traces of PFAS because of the use of PFAS-containing products in our daily living environments like carpets, furniture, non-stick pans, food packaging, cosmetics, cleaners, electronics, waxes, clothing and possibly drinking water. Enhancements to allow septic systems to treat PFAS and other emerging contaminants are being researched. At this time, there are no practical solutions for removing PFAS from septage or from farm soil. Higher soil organic matter, which is an added benefit of using septage (and biosolids), has been demonstrated to bind PFAS in the soil, thus slowing the chemicals from moving into groundwater or plants.
The most effective way to reduce PFAS from wastewater entering our groundwater, surface water, or crops is to eliminate their usage whenever possible. Proper disposal of items is crucial to avoid contamination of the water supply. Avoid pouring hazardous materials like medication, paint, motor oil, and pesticides down the drain. Do not flush items such as paper towels, feminine hygiene products and flushable wipes as they often contain PFAS and can clog your pipes. Other household items that commonly contain PFAS and should not go down the drain include liquid cleaning products, floor waxes, glass cleaner, aerosol cleaners, nail polish, eye makeup and dental floss.
Because labeling of PFAS is not required at the federal or state level, it is hard to know if the products you are using contain PFAS. Beware of misleading claims such as “PFOA and PFOS free” as there are thousands of PFAS chemicals, not just those two. Look for safer alternatives from companies that have been certified by credible independent organizations to be PFAS-free.
If you would like more information about PFAS in Michigan agriculture, visit our website at https://www.canr.msu.edu/pfas/
