UNIVERSITY PARK, Pa. — In the early 1990s, farmers across the U.S. began employing a seemingly environmentally sustainable practice of applying wastewater treatment residuals to crops as fertilizer. While this still common approach provides nutrients for plants, it also contaminates soil with “forever chemicals,” or per- and polyfluoroalkyl substances (PFAS), which are now known to contribute negative health and environmental impacts, according to researchers at Penn State.
Some states have started to move away from the practice, but wastewater treatment byproducts still need to be disposed, so they have turned toward depositing them in landfills. However, the impacts of this new practice are not well understood. Onur Apul, associate professor of civil and environmental engineering (CEE) at Penn State, aims to close that knowledge gap with a recently awarded two-year, $200,000 grant from the Environmental Research and Education Foundation (EREF). Apul is also working on another project investigating PFAS in drinking water funded by a U.S. National Science Foundation (NSF) Engineering Research to Advance Solutions for Environmental PFAS (ERASE-PFAS) grant, and he received an NSF Rapid Response Research (RAPID) grant to investigate environmental impacts of PFAS in firefighting foam.
In this Q&A, Apul, who joined the Penn State CEE faculty in August, spoke about his ongoing PFAS research.
Q: What are PFAS, and what impact do they have on people and the environment?
Apul: PFAS are a group of human-made compounds that were created as superior surfactants, or substances that lower the surface tension of a liquid, making it easier for things like oil and water to mix. They were superior to other surfactants because they could resist thermal, chemical and biological stressors. They owe their desirable properties to strong carbon-fluorine bonds in their molecular structures. For this, they have been extensively produced or imported. Generally, they are associated with firefighting foams and nonstick surface coatings. However, as one can imagine, PFAS still persist in the environment after these products reach the end of their useful life. In other words, PFAS are pretty useful compounds when we need them, but they don’t simply go away when we are done with them. Once PFAS are in the environment, they become a part of the food web, indoor air and the global water cycle. As virtually indestructible and toxic compounds, their widespread presence is quite alarming. Because of this, I believe PFAS are causing one of the most prominent global public health crises related to environmental pollution in the modern ages.
Q: What do you hope to achieve with the EREF-funded project? How might your findings inform public policy?
Apul: Our EREF-funded project is to create a fundamental understanding of PFAS release from PFAS-laden biosolids in landfill environments. It is becoming apparent that biosolid land applications, especially for agricultural uses, need to be re-evaluated. One pragmatic and widely available disposal alternative for biosolids is landfilling. However, biosolids can have high levels of PFAS and may cause a cascading problem due to PFAS release in landfills. In this project, we are going to systematically evaluate what kind of PFAS, under which landfill conditions and what type of leachate chemistry, will facilitate PFAS release. Our aim is to guide policy makers with actual data. Some states, such as Maine, have been abandoning land application, and this project will provide input for mindful decision making.
Q: Are there other instances where treatment or purification results in PFAS contamination?
Apul: I’m working with David Mazyck, professor and head of the School of Engineering Design and Innovation, on a project related to the disposal of PFAS-laden drinking water residuals, such as exhausted filters. The core principles of both projects are very similar as they both investigate management options for PFAS-laden solid waste. The project on drinking water residuals particularly looks into management alternatives for PFAS-laden granular activated carbons, which are one of the benchmark technologies for PFAS treatment. We use activated carbons for applications like water treatment. After their use, spent activated carbons could be disposed, reactivated or incinerated. Each option has a complex set of consequences and interesting chemistries. This project will also complement my ongoing NSF PFAS ERASE project that investigates thermal regeneration of PFAS-laden filtration systems as a means to stop the PFAS circulation in the environment.
Q: What other PFAS-related challenges are you researching?
Apul: We were recently awarded an NSF RAPID project to investigate the long-term impacts of a firefighting foam spill in Brunswick, Maine. The spill is considered one of the largest foam spills in the nation’s history and has already devastated environmental quality. Our PFAS research team is equipped with soil, water and shellfish sampling expertise, and, as soon as we found out about the spill, we were readily available to deploy researchers to build a repository of surface water, tap water, groundwater, shellfish and soil samples. This project is as “real-world” as it gets because we are dealing with an emergency spill, and its consequences are unfolding day by day.
With the same research team, we are also helping Professor Arjun Venkatesan at the New Jersey Institute of Technology to remove certain types of PFAS from drinking water sources. It became apparent that these PFAS are problematic in water utilities, and Dr. Venkatesan’s group created a novel solution for this.
PFAS research is multifaceted. There are several aspects of PFAS research including alternative PFAS-free material creation, surface science, life cycle assessment, treatment and remediation, public awareness, outreach and education. These problems are ongoing, and, as we learn more, we will need a trained workforce in this country to help solve them. Strong and consolidated PFAS research will help by not only providing cutting-edge solutions but also by contributing to a rigorously trained workforce.