By: Todd Williams, Jacobs

Summary: Since the U.S. Environmental Protection Agency (EPA) released its draft risk assessment of PFOA and PFOS in sewage sludge on January 14th, responses have ranged widely – from alarmist fears to complete dismissal. Let’s look at what the science says, why perspective matters, and how the industry can move forward with innovation, adaptability and common sense.

By now, most readers have at least some awareness of PFAS and biosolids. Since the U.S. Environmental Protection Agency (EPA) released its draft risk assessment of PFOA and PFOS in sewage sludge on January 14th, responses have ranged widely – from alarmist fears to complete dismissal. The original deadline for public comments, April 16, has been extended to August 14 due to the significant public and industry response.  This extension is a welcome decision, as the 272-page assessment deserves thoughtful, evidence-based feedback from the environmental and research communities.

Rather than analyzing the assessment itself, I want to share a broader perspective on biosolids and their use on land. As a professional engineer with more than 40 years in wastewater treatment, I’ve spent my career advancing technologies that improve biosolids products – products that are essential to protecting public health and the environment.

When I began exploring PFAS in biosolids seven years ago, research on the topic was very limited. Much of the early literature focused on land application of biosolids with PFAS far above typical concentrations – biosolids that should never have been applied due to industrial contamination of the wastewater treatment plant’s influent. Unfortunately, many of those articles are still being cited today as though they represent the norm. They don’t. And they shouldn’t dictate public perception or policy around responsible biosolids management today or in the future.  

It's important to recognize the well-documented benefits of high-quality biosolids when applied properly to land. These benefits were established through decades of credible research dating back to the 1970s, ’80s and ’90s – work led by respected researchers such as Dr. Rufus Chaney of the USDA, Dr. Wiley Burge, Dr. Eliot Epstein, Dr. Terry Logan, Dr. James Ryan, Dr. Alan Page, and John Walker of the EPA. And let's not forget Dr. Al Rubin, who oversaw EPA's Part 503 regulation in the early ‘90s – a regulation that is still in place today and was developed with a risk management component that was missing in EPA’s current draft risk assessment. I urge any newcomers to the municipal wastewater treatment industry to research those published scientific journals and understand the foundation that was laid regarding biosolids land application and its benefits. Their findings still hold value and relevance today. 

The documented benefits of biosolids land application include:

• Replenishes depleted organic matter in soil
• Provides key nutrients like nitrogen, phosphorus and potassium
• Delivers slow-release nutrients that are absorbed more efficiently and reduces leaching compared to chemical fertilizers
• Provides beneficial trace elements such as calcium and magnesium, which are typically not found in chemical fertilizers
• Improves soil structure, including increased porosity
• Frees up much-needed space in landfills
• Provides an opportunity for farmers and cities to work together in a mutually beneficial, cooperative venture
  

Today, we have an equally talented research community. Scientists such as Dr. Sally Brown (University of Washington), Dr. Jay Gan (UC Riverside), Dr. Ganga Hettiarachchi (Kansas State), Dr. Drew McAvoy (University of Cincinnati), Dr. Ian Pepper (University of Arizona), and Dr. Tom Young (UC Davis) have submitted detailed, science-based feedback on the EPA’s draft assessment. Their comments emphasize the need for field-based studies that reflect realistic application scenarios and environmental conditions.

Others, including Dr. Linda Lee (Purdue) and Dr. Ian Pepper, are conducting field studies on PFAS movement, plant uptake, and other outcomes in non-industrially impacted biosolids. Michigan’s Department of Environment, Great Lakes and Energy (EGLE) has taken a source control approach – requiring pretreatment at industrial facilities, not wastewater plants. Their efforts have dramatically reduced PFAS levels in biosolids, and subsequent research shows negligible PFAS in land application sites and nearby waters when pretreatment is in place. The EPA has publicly endorsed this strategy. Source control works!

Despite this, several states have enacted or are considering laws to restrict biosolids land application due to the presence of measurable PFAS. The reality is that PFAS are ubiquitous in modern society – and we all contribute to that. Wastewater treatment plants are passive receivers of these compounds, and biosolids will continue to contain low levels as long as PFAS remain in widespread use.

The solution is twofold: reduce PFAS use in consumer and industrial products and continue research to weigh biosolids risks against their benefits. If future regulations require changes in how biosolids are managed, utilities and engineers must view this as an opportunity – not just a challenge. We should take a systems-level approach to biosolids programs that includes energy optimization, carbon sequestration and greenhouse gas reduction.

Here are key trends we can expect in biosolids management:

• Greater focus on reducing solids through digestion, dewatering and drying
• Continued land application of Class B biosolids, with more limitations
• Increased production of Class A biosolids for non-agricultural reuse
• Less reliance on landfilling
• More focus on industrial pretreatment to reduce micro-pollutants

• Development of technologies to remove PFAS and other emerging contaminants from biosolids

• Greater energy recovery from solids to reduce emissions and energy use
• Creation of biochar and other low-contaminant byproducts
• Flexible, adaptable programs to meet evolving regulations

As environmental professionals, we must commit to ongoing education, rely on solid science, and continue to improve our biosolids systems. PFAS are a real concern, but the sky isn’t falling. With smart planning, continued research and proactive system improvements, we can address emerging challenges while maintaining the environmental and agricultural value of biosolids.

About the Author

Mr. Williams has a 40+ year career in environmental engineering and currently serves as Jacobs’ Global Principal for Residuals Resource Recovery and Biosolids Management. Todd has supported dozens of biosolids and residuals management master plans throughout his career, including adaptive planning to manage emerging contaminants such as PFAS. Based in Charlotte, North Carolina, Todd is an engineering graduate of Virginia Tech and previously served as the Chair of the Water Environment Federation’s Residuals and Biosolids Committee.