Wastewater biosolids (sewage sludge) are an inevitable by-product of modern wastewater treatment. Flushing the toilet and washing the dishes or laundry are everyday activities that contribute to biosolids being collected at a wastewater treatment facility. Commercial and industrial sewer discharges can also add to biosolids. If your home is not connected to a sewer, when you have your septic tank pumped, the collected septage is hauled to a wastewater treatment facility for processing and also brings in more biosolids.  

Wastewater treatment plants clean the water they receive and collect the residual solids that are left behind. These solids are rich in organic matter and nutrients.  

Biosolids must be disposed of in some way. One of the most environmentally friendly options is to reuse biosolids as fertilizers. Typically, farmers use biosolid fertilizers for hay and other crops, replacing man-made fertilizers that require a massive environmental impact to create. Biosolids are strictly regulated by federal and state rules and only those meeting established standards can be land applied.  

Alternatively, biosolids can be disposed of through landfills or incineration. 

Recent advances in laboratory analysis have revealed that Per- and Polyfluoroalkyl Substances (PFAS) are present at trace levels in biosolids. There is concern PFAS in biosolids could make its way into crops, livestock feed and groundwater and then into people via food or drinking water.  Some PFAS compounds have been associated with possible health effects. 

PFAS, also known as Forever Chemicals, are manmade chemicals produced by companies like 3M and DuPont. These chemicals have many uses and most notably are water, grease and heat resistant. Some common uses include firefighting foam, fabric waterproofing, stain resistant carpets and upholstery, non-stick cooking pans, cleaning materials, fast-food wrappers, makeup and even toilet paper.  

The prevalence of PFAS in everyday items has resulted in wastewater treatment plants receiving most of their PFAS contamination from households. Some industrial uses may also contribute higher levels of PFAS but the baseline contamination in wastewater appears to be from domestic use. 

Wastewater treatment processes do not destroy PFAS, so some of these chemicals can end up in biosolids or may be discharged to receiving waters.  The first and most effective way to eliminate PFAS is source control to keep these chemicals out of everyday products. PFAS are specifically made and used by manufacturing companies. The intentional addition of PFAS to products can be curtailed through voluntary, regulatory and legislative efforts. Until source control is achieved, there will continue to be PFAS in wastewater.   

Additionally, more research on which products contain PFAS and the health risks posed by these products is critical. While there is evidence that high concentrations of some PFAS compounds pose a health risk if ingested over many years, there remain many questions about the risk posed by very low levels and the health concerns associated with most of the thousands of different PFAS chemicals. The mere presence of PFAS in products or the environment (air, water and soil) does not mean there is a risk of harm to health or wildlife. The ability to detect PFAS at single digit part per trillion levels assures that PFAS will be found in many types of media but does little to inform the public of the risk posed.    

In the fall of 2024 the MCWRS Board of Directors, in conjunction with Coalition members, developed a position paper to address biosolids reuse and disposal with a recommended path forward that is responsible, sustainable, and effective.