What Are Biosolids?

One of the greatest public health achievements of our time is modern wastewater treatment. Before its advent, our rivers were contaminated and unfit for human contact, fish populations were decimated, and sewage-related diseases such as dysentery and cholera were widespread. Thanks to the Clean Water Act of 1972, wastewater treatment facilities were built and improved throughout the US. In addition to the immediate public health benefits of clean water and disease prevention, biosolids – byproducts of wastewater treatment – have also proven to be very beneficial.

Biosolids are nutrient-rich soil conditioners that come from wastewater treatment: that is, from your poop. What you flush down the toilet can be reused as a valuable soil nutrient, through scientifically-developed wastewater treatment processes. By reusing biosolids instead of burying them in landfills, our utility bills can be kept down, our environment can be improved, and farmers can have better soils for growing healthier crops.

How Does it Work?

Sanitary waste in Livingston County and surrounding areas is treated in various ways, by different municipal utilities. Typically our cities, villages, and parts of some townships have their own wastewater treatment plants. Some townships have sewage treatment service provided through adjacent municipalities, and some townships (or parts of them) are served through multi-jurisdictional agencies. A few residential communities have their own treatment and disposal systems, which are operated by the Livingston County Drain Commissioner.

Wastewater Treatment in our Area

About 40% of households in the Livingston County are served by municipal wastewater treatment systems, and around 60% (some 50,000) have their own on-site septic systems, from which septage is typically pumped by commercial haulers and taken to Livingston County’s Septage Receiving Station. Wastewater treatment services are similar for communities bordering Livingston County, such as western Oakland County.

Each of these facilities, while they produce clean water, also filter out solids … again, from your poop. These solids are filtered out, dried, pressed, and/or thickened to reduce volume and cut the cost of hauling. Once properly treated in accordance with strict state and federal regulations, these solids are now referred to as biosolids, and they are safe for application to farmland and gardens as a beneficial soil amendment. It’s reuse and recycling at its best.

Are We Reusing/Recycling Biosolids?

This is exactly what many wastewater treatment facilities in our area do: they have their biosolids pumped from their facilities by commercial biosolids firms, delivered to farm fields in the area and applied to the soil. Many treatment facilities in the area, and many farmers, have been doing this for decades.

Are Biosolids Safe?

Biosolids have been used successfully for a long time by farmers here and across the country, to improve soil health and grow better crops. Milorganite is a commercially available example of biosolid that is used on home gardens. Strict federal and state regulations have been in place for years to assure the safety of biosolids, which are regularly tested and monitored to meet the highest standards of quality. They are a safe, economical and natural alternative to petrochemical-based fertilizers like ammonium nitrate, potassium sulfate and superphosphate. This is supported by hundreds of scientific studies over the years. These quality standards assure that the use of biosolids in the production of crops for human consumption, when used according to federal guidelines, is completely safe. This is attested by the EPA and the National Academy of Sciences.

Classes of Biosolids

Biosolids are classified either as Class A or Class B.  Class A biosolids are treated to the highest standards – usually by composting, pasteurizing, heating or drying – to have no detectable levels of pathogens. Because they are safe for casual contact, they are often used in such places as home lawns and gardens, parks and golf courses, as well as farms. Milorganite is commercially-available example of a Class A biosolid that you may have used at your home.

Class B biosolids are typically dewatered or thickened to a thick liquid or semi-solid state. They are treated to significantly reduce pathogens, typically to a reduction on the order of 99.99%, often lower than animal manures. They are applied to the subsurface of farmlands and mixed into the soil to support healthier crops. Farmers often prefer Class B biosolids because they contain more plant-available nutrients.

Do They Smell? Are They a Nuisance?

Biosolids used in home or community gardens may have a slight earthy smell, and those used in farming may have a smell similar to animal manure, but these smells fade quickly after application. Treatment and application standards ensure that they do not attract harmful pests. And while there may be very low levels of metals in biosolids, similar to levels found in urban soils, they are well below levels that would pose a health risk.

If Biosolids Are So Beneficial, Then Why Don’t All Facilities Produce Them?

Wastewater utilities in our area work hard to keep costs and rates down, while providing safe, effective and reliable services.  So, for some, it may be more economical to have their biosolids hauled away and landfilled, rather than having them land-applied, as space to store biosolids until they can be applied may be limited. Alternatively, their wastewater solids may not meet biosolids standards, and the costs [to] for making them meet those standards may be prohibitively high.

As for septage from individual septic systems, the Livingston County Septage Receiving Station was built to support a ban on land application of septage, passed by Livingston County in 2007. Raw septage, unlike treated biosolids, contains high concentrations of pathogens that can be harmful to human health and the environment, which is the reason for the 2007 ban. So unless a treatment process is added that can convert its solids into biosolids (currently cost-prohibitive), its solids must continue to be landfilled

So What’s the Problem?

As landfill space shrinks, landfilling of biosolids becomes more expensive.  Regulators urge all solid waste to be beneficially reused wherever possible to conserve landfill space. At the same time, the cost of turning wastewater solids into biosolids is increasing, as more wastewater plants have had to add presses and dewatering equipment to reduce volumes. Additionally, the cost of transportation, energy and treatment supplies are all going up.

While pressures to move away from landfilling are increasing, land application is growing more under threat. Farmlands available for land application are becoming more limited in our area. Plus, some people have the misconception that biosolids pose a threat to human and environmental health, which is untrue. A current concern is PFAS in biosolids, whereas the opposite is true: strict regulations are in place to keep chemical and metal concentrations safely below set limits.   But, there will always be trace concentrations of something, and each news cycle seems to bring some new concern – whatever the actual health risk is. Lately it’s PFAS. Nonetheless, misconceptions can fuel a bias against land application of biosolids. All of these factors are a threat to the beneficial reuse of biosolids, and a threat to effective and affordable wastewater treatment service.

What About PFAS?

PFAS (per- and polyfloroalkyl substances) are found in all kinds of common products: food packaging, clothing, household cleaners, carpeting, upholstery, child car seats, beauty products, dental floss, nonstick pans, water-resistant wear and firefighting foam. PFAS are long-lasting chemicals, parts of which break down very slowly over time. Due to their durability, they have been used in a wide variety of industrial processes since the 1940s.

Because of their long and widespread use, trace amounts of PFAS can be found almost everywhere in our environment, in such faraway places as the Arctic; they are found in our homes, and in our bodies; and also in biosolids, as they pass into our waste streams. True, there have been isolated cases of unacceptably high levels of PFAS in biosolids. A case of PFAS from an industrial source entering the waste stream of one facility unfortunately happened in our area. Land application of biosolids from that one facility was halted. Incidents like this have prompted regulators to monitor PFAS in biosolids even more closely. The current situation has exposed the need for more effective PFAS-related regulations, and more research.  It also makes the issue ripe for the spread of falsehoods and unfounded fears.

PFAS research and regulations are in flux, and because of this, it is very challenging for utilities to plan how to manage their biosolids for the future. This can lead to major unplanned costs and diverting of scarce resources from other priorities.  Utility managers, and the customers they serve, have a big stake in how biosolids and PFAS are regulated. For this reason, the water/ wastewater industry is in the forefront of research and innovation on the issue.

Importantly, scientific research has shown that human exposure to PFAS from common household products is far greater than from PFAS in biosolids.  In fact, our exposure to PFAS in biosolids is unlikely or minimal. There may be trace amounts of PFAS in biosolids, often measured in parts per trillion. One part per trillion is like one second in 32,000 years, or one drop of water in 20 Olympic-size swimming pools. These are exceedingly small amounts. The use of biosolids-enriched soils for producing crops for human consumption is scientifically-proven to be safe. And as PFAS are discontinued, the trace levels become even lower.

Beneficial Reuse of Biosolids, Where Possible, is a Must

Safe and economical wastewater treatment, and the incalculable benefits it brings, is a cornerstone of modern public health. It has resulted in the vast reduction of major diseases and epidemics, and in the return of clean water to the environment. Clearly these are important benefits – too important for its affordability to be put at risk through unfounded fears and ignorance. Important also is the beneficial reuse, and the return to the land, of biosolids produced from wastewater treatment. We must preserve our ability to beneficially reuse biosolids.

About This Information

This information was prepared in cooperation with utility managers in the Livingston County and West Oakland County area, and includes information from the US EPA, Michigan EGLE, and the Water Environment Federation.