"False"
Skip to content
printicon
Main menu hidden.
Published: 2024-09-19

Forever chemicals persist through waste incineration – can spread to the environment

NEWS PFAS, often called "forever chemicals," present in municipal solid waste can survive the high temperatures of waste incineration and continue to spread into the environment via residues from waste-to-energy plants. A new doctoral thesis from Umeå University’s Industrial Doctoral School reveals that the most common type of PFAS found in ash, condensate, and flue gases is also the most challenging to capture once they have entered the environment.

The research, initiated by the collaboration partner Umeå Energi, aimed to uncover the fate of PFAS during the handling and incineration of municipal solid waste.

“When we began this project a few years ago, there was very little research on PFAS behavior in large-scale waste-to-energy facilities. Now, an increasing number of studies, including those from our research group, confirm that PFAS are not completely destroyed during incineration and can be found in the byproducts of the process,” says Sofie Björklund, doctoral student at the Department of Chemistry and the Industrial Doctoral School.

Short-chain PFAS most common

The research found that short-chain PFAS were the most common compounds identified, both in the leachate from unburned waste and in the ash, condensate, and flue gases produced during incineration.

“This is concerning because short-chain PFAS are highly mobile in water and difficult to capture once they have entered the environment. What we need to determine next is whether these shorter PFAS are breakdown products of longer-chain PFAS,” says Sofie Björklund.

One of the studies in the thesis examined the efficiency of flue gas cleaning in reducing PFAS levels. The results showed that wet flue gas treatment removed an average of 35 percent of total PFAS, though the effectiveness varied significantly depending on the specific PFAS compounds.

About PFAS

Per- and polyfluoroalkyl substances (PFAS) are a large group of chemicals used in products like stain-resistant carpets, grease-resistant food packaging, water-repellent clothing, ski wax, and firefighting foam. Known for their extreme environmental persistence, some PFAS are classified as persistent organic pollutants. In Sweden, several incidents of PFAS-contaminated drinking water have been linked to the use of firefighting foam. PFAS exposure has been associated with adverse health effects, including elevated cholesterol levels, lower birth weights, and weakened immune function.

The thesis also highlights that adding five percent of sewage sludge from wastewater treatment plants to regular waste fuel could increase the annual emissions of PFAS from the incineration plant by three to four times compared to burning regular waste alone.

“It’s likely possible to optimize flue gas cleaning to capture even more PFAS. A hazardous waste incineration plant in Belgium has already had success in this area,” says Sofie Björklund.

Despite these findings, she notes that waste-to-energy plants are not the sole source of PFAS emissions.

“There are several other major sources, such as firefighting training sites and wastewater treatment plants, which likely contribute significantly more PFAS to the environment. That said, minimizing PFAS emissions wherever possible is critical, as these chemicals persist in the environment indefinitely.”

Exploring breakdown products

Åsa Benckert, senior environmental engineer at Umeå Energi, emphasizes the need for better end-of-life planning for products containing PFAS. When products are brought to market, there’s often no plan for how they will be handled once they become waste. There is till a lack a full understanding of what happens to different substances in the collection and treatment chain.

“It’s clear that PFAS from consumer products aren’t fully destroyed by current waste management practices. More research is needed to understand exactly what happens during incineration and how we can reduce the spread of these harmful substances,” she says.

The research team plans to expand their studies, focusing on the conditions under which PFAS breakdown might occur and identifying the resulting breakdown products. To support this work, a new doctoral student has joined the group.

About the thesis defence

On Friday 27 September Sofie Björklund, Department of Chemistry, will defend her thesis entitled Exploring the occurrence, distribution and transport of per- and polyfluoroalkyl substances in waste-to-energy plant. The defence will take place at 9.00 in Stora Hörsalen (KBE303), KBC building. Faculty opponent is Professor Ian Cousins, Department of Environmental Sciences, Stockholm University.

Read the full thesis

About the Industrial Doctoral School

The Industrial Doctoral School is based on collaboration between the University, researchers and businesses or organisations. The aim is to combine benefits for both society and the external party while training new high-quality researchers. The doctoral student also receives a tailored academic course package. The doctoral school is open to all disciplines and the doctoral student is employed at Umeå University.

Read more on the Industrial Doctoral School website