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Breaking Down Biosolids: New Challenges Faced By Wastewater Treatment Plants

In times where water scarcity is becoming a growing concern, repurposed water is an essential lifeline. Everything that goes down the drain into the sewage collection systems needs to be processed and treated so that it can continue its water journey and be repurposed elsewhere. This includes processing biosolids - organic matter collected from sewage.

Working with biosolids is a key component of wastewater treatment across the country.

The solids, in this case, are treated by introducing chemical and physical treatments into the collected sewage with the end goal of creating a more nutrient-rich final product. Biosolids that are repurposed, say for use in agriculture, have to meet strict state and federal requirements when it comes to health and safety before they can be discharged into the environment or reused for land reclamation.

There is a problem with biosolids, however, and this problem is causing substantial headaches in the wastewater treatment industry. That problem? Unprecedented levels of chemical pollution. Compared to previous decades, wastewater treatment plants have had to ramp up the number of processes they put biosolids through before they can be safely released.

The Basics Of Biosolids

But why go to all this trouble to make biosolids usable? Why use biosolids at all? Well, biosolids, once processed, can have numerous benefits in the industrial and environmental sectors. They’re also more natural than using synthetic options that are loaded with toxic chemicals. With additional nutrients injected by the wastewater treatment process, the biosolids can actually help improve soil structure, support water reuse, take the pressure off non-renewable resources, and even cut down on the need for synthetic fertilizers.

Synthetic fertilizers and man-made compounds are some of the biggest threats to soil health - think about all that runoff going into the groundwater or affecting crops. This is where biosolids greatly differ, provided the right treatment steps have been followed during the wastewater handling process.

There are numerous guidelines set forward for wastewater treatment by federal regulators, and that includes how the biosolids are handled before, during, and after they leave the wastewater treatment plant. Left unregulated, these materials can potentially pose serious harm to human and environmental health. That’s why biosolids are divided into two different classes based on their treatment methods, and the types of pollutants and pathogens that they may present.

Class A treatments are targeted at the removal of pathogens and viruses in biosolids, while Class B does the same but takes additional steps to ensure the end product can be used for crops, animal watering, or other public use. The regulations surrounding these classes are strictly enforced by federal regulation 40 CFR Part 503, and individual states are likely to have their own additional requirements depending on what the end product biosolids will be used for.

Understanding Biosolids In Everyday Use

Biosolids are used for multiple purposes in everyday life, forming a key part of agriculture, mining, and many other industrial purposes. Let’s discuss the most common below:


The agriculture sector is one of the most prominent users of biosolids post-wastewater treatment. Being rich in nutrients like nitrogen that is considered advantageous for crops and vegetation, treated biosolids are highly valuable to farmers looking to eliminate the use of synthetic fertilizers. As already mentioned, chemical fertilizers can be dangerous to groundwater and are not sustainable for long-term use in fragile environments.

Land reclamation sites

In areas where the land may have been damaged such as by being a waste storage site, biosolids can be used to encourage new vegetation growth, reduce toxicity in the soil, manage soil erosion and regenerate damaged soil layers. This is commonly used in old mining sites to restore the topsoil following years of hard treatment.

Where there is no topsoil present, land reclamation and the use of biosolids are a natural way to introduce stimulating nutrients into the earth.

Forested Areas

Multiple studies have found that the use of biosolids in forested areas encouraged faster timber growth and production. In deforested areas, biosolids can be used to stimulate regrowth and encourage restoration to the environment.

Residential Gardening

Biosolids that meet the most stringent requirements in terms of cleanliness and safety are commonly used in residential gardening and can be easily purchased from hardware stores, gardening centers and wastewater treatment plants themselves. They are used in the place of chemical fertilizer and are also commonly used in public parks.

The Challenges Of Biosolid Treatment Today

Something that very few people think about is what happens to the biosolids before they even reach the wastewater treatment plant - meaning what happens after the initial flush.

Today’s biosolid treatment processes are becoming increasingly complicated due to the number of household chemicals and pharmaceutical drugs going down the drains. Research conducted by the U.S. Geological Survey (USGS) found that nowadays, biosolids contain a much higher number of chemical concentrations than they did just a few decades ago.

Where do these high concentrations of chemicals come from? Mostly from humans. Household cleaning chemicals are a big offender, as are certain medications that are pushed into the sewage collection system. Other sources of water pollution are also causing issues, whether it be from poorly-policed industrial businesses or from runoff coming from dumping sites.

In general, wastewater treatment plants generate a bit under 10 million dry tons of biosolids per year. Half of this total is typically dedicated to the agricultural sector, wherein they need to meet the strict requirements set for the nutrient and pathogen levels set by the state. This is where the problem with biosolids today comes in.

With biosolids now being tainted by more man-made chemicals, wastewater treatment processes need to go further to reduce or remove them. For the plant, this is an expensive venture - a choice between adding new specialist equipment and filtration systems and being fined for not complying.

The same study conducted by the U.S. Geological Survey (USGS) into the quality of biosolids found that:

  • Out of the samples collected, at least one in ten were found to have two-thirds more household and pharmaceutical chemicals than average.

  • At least twenty-five of the almost ninety chemicals being measured in biosolid samples included pharmaceuticals that could cause hormonal issues, that were disinfectant, fragrance, or antihistamine.

A Closer Look At Biosolid Pollutants

The risk of biosolid pollution should not be underestimated. Biosolids permeate many essential agricultural processes, and without careful testing, pollutants can be introduced to a fragile ecosystem and wreak havoc.

The EPA states that there are around five hundred pollutants that are now found to be present in biosolids in wastewater treatment plants. At the same time, not every plant will present the same pollutants and will depend highly on the location and the source of the wastewater being collected. A densely populated area like a city may be more likely to have a presence of pharmaceuticals in their biosolids than a spread-out rural area like a farming town.

What Makes The Use Of Biosolids Safe?

Biosolids, when treated for all of the potential risks, can be highly beneficial for the environment. Synthetic fertilizers, on the other hand, are an environmental disaster waiting to happen.

Some of the key ingredients in synthetic fertilizer are nitrogen and hydrogen, effectively forming liquid ammonia when combined. This formulation might be useful for spiking growth in crops, but the water runoff has caused a significant increase in the levels of man-made compounds in the soil.

Biosolid treatment can take place long before the sewage actually reaches the wastewater treatment plant. In some states, the industrial sector is tasked with pre-treating their water runoff to ensure that the majority of pollutants have been removed before it even goes into the sewage collection system.

Despite this additional step, wastewater treatment plants still need to take careful measures to monitor the incoming sewage and ensure that everything is compatible with the in-plant treatment processes. Most plants rely on biological filtering options that simultaneously clean the wastewater and removes the majority of excess solids. The remaining biosolids are then further treated to ensure they are pathogen-free and ready to be released into the environment.

What makes biosolids particularly safe beyond that they are fully natural is that they have been heavily studied and regulated by the U.S. Environmental Protection Agency (USEPA). This means there is a substantial amount of research regarding the safe use of biosolids in things like agriculture. This research has further been backed by the National Academy of Sciences which has taken regulations and public safety into account and echoed the result: biosolids are safe for public use and even consumption as long as they have been treated according to current guidelines.

In-Pipe And Improving Wastewater Compliance

The success of a wastewater treatment plant is highly dependent on its ability to comply with local and federal regulations.

With the breakdown of organic material being such an essential part of the treatment process, dealing with biosolids effectively is key. This includes taking on higher concentrations of household and manmade chemicals than ever before. Removing harmful chemicals like nitrogen, phosphorous and more is an important part of pleasing regulators, but doing so requires continuous monitoring and testing.

This is where In-Pipe technology can make all the difference. For plants that are constantly struggling to maintain the right nutrient levels, the In-Pipe method provides a natural biological solution that can reduce running costs long-term.

From the moment waste enters the sewage collection system, the In-Pipe method creates a bioreactor that works the entire time that the biosolids and wastewater are being handled by the plant. By introducing highly effective bacteria into the sewage system, the In-Pipe approach is able to:

  • Reduce sewer organics by as much as 40%

  • Be more effective than the average bacteria found in wastewater

  • Decrease the total amount of influent Nitrogen (TKN)

The above means that plant operators can drastically change how much carbon filtration is needed for the wastewater management process. For those in the know, carbon is one of the more expensive materials used during in-plant treatment, and being able to cut down on its use will drastically reduce running costs.

Help your wastewater treatment plant work smarter, not harder. Contact our team to find out more about our science-based treatments.

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