PFAS in Landfill Gas

Landfill Gas: A Major Pathway for Neutral Per- and Polyfluoroalkyl Substance (PFAS) Release
Ashley M. Lin, Jake T. Thompson, Jeremy P. Koelmel, Yalan Liu, John A. Bowden, and Timothy G. Townsend
Environmental Science & Technology Letters 2024 11 (7), 730-737
DOI: 10.1021/acs.estlett.4c00364

Landfill Gas: A Major Pathway for Neutral Per- and Polyfluoroalkyl Substance (PFAS) Release | Environmental Science & Technology Letters (acs.org)

Per- and Polyfluoroalkyl Substances (PFAS) do not occur in nature, they are an entirely synthetic substance. Yet, most people in the United States have been exposed to PFAS and have PFAS in their blood, especially perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). 

 There are thousands of PFAS chemicals, and they are found in many different consumer, commercial, and industrial products. PFAS has been widely used for over 80 years mainly for their ability to repel oil, grease, water, and heat. PFOS and PFOA found in Scotch Guard and an ingredient in Teflon and traditional Aqueous Film-Forming Foam (AFFF) - the firefighting foam used to fight aviation and other chemical fires -were the first to become widely commercially successful providing stain resistant and flame resistant treatments to carpeting, upholstery, clothing.

PFAS  has been used in many consumer products. Spray coatings to cans and food packaging. Food with PFAS containing packaging picked up traces of PFAS and it was passed onto people and thus found its way into waste water treatment plants’ effluent and the biosolids. The reach and spread of PFAS was increased because effluent from wastewater treatment is released to rivers and used as source water for drinking water or irrigation.

Not surprisingly these PFAS containing consumer products and commercial waste, such as children’s clothing, cosmetics and wastewater treatment sludge solids ultimately end up in landfills. In the article cited below, Timothy Townsend and colleagues previously established that PFAS-containing waste, called leachate,  can contaminate the water that seeps through landfills.

This leachate is usually captured and treated before entering the environment. Landfills also produce gas that can be captured and controlled, but unlike leachate, it’s often released untreated. Landfill gas is generated during the natural process of bacterial decomposition of organic material contained in the trash buried in the landfill. Landfill gas is approximately forty to sixty percent methane, with the remainder being mostly carbon dioxide. Landfill gas also contains varying amounts of nitrogen, oxygen, water vapor, sulfur, and other contaminants including it seems PFAS. The gases produced within the landfill are either collected and flared off or used to produce heat and electricity. The landfill gas cannot be allowed to build up in the landfill because of the explosive potential.

The landfill gas is mostly made up of methane and carbon dioxide; however, two recent studies also discovered a subset of airborne PFAS called fluorotelomer alcohols, which have the potential to be toxic when inhaled and can be transported long distances. Since the prevalence of PFAS-contaminated landfill vapors isn’t yet widely known, Townsend, Ashley Lin and their team wanted to identify and measure them in vented gas at three sites in Florida.

As recounted in the research cited above, the researchers pumped landfill gas from pipes through cartridges designed to capture the airborne PFAS. They freed the compounds from the cartridges with organic solvents and analyzed the extracts for 27 PFAS, including fluorotelomer alcohols. The found 13 of the 27. Their study reports unexpectedly high levels of airborne PFAS at three landfills and demonstrates that vented gases and landfill leachates could transport similar amounts of these contaminants to the environment.

The researchers also collected leachate samples at the Florida sites and analyzed them for PFAS commonly found in water samples. From this data, they estimated that the annual amount of fluorine (as a proxy for PFAS content) leaving the landfills through gas emissions could be similar to, or even greater than, the amount leaving through leachates.

Because landfills are repositories for PFAS, this work indicates that vented gas from these sites should be considered in future mitigation and management strategies to reduce potential inhalation exposure and release to the environment of PFAS. Some landfills burn the vapors or trap them for energy production (as does Prince William Landfill), and the researhers suggested that further research is needed to determine the degree of removal these treatments provide for airborne contaminants.

 

 Chen Y, Zhang H, Liu Y, Bowden JA, Tolaymat TM, Townsend TG, Solo-Gabriele HM. Evaluation of per- and polyfluoroalkyl substances (PFAS) in leachate, gas condensate, stormwater and groundwater at landfills. Chemosphere. 2023 Mar;318:137903. doi: 10.1016/j.chemosphere.2023.137903. Epub 2023 Jan 17. PMID: 36669537; PMCID: PMC10536789.