Study Identifies 'Forever Chemical' Characteristics Affecting Drinking Water Treatment Effectiveness
A new study by researchers at Hanyang University suggests that per- and polyfluoroalkyl substances' (PFAS') fluorinated carbon chain length plays a significant role in how the compound behaves in the environment and responds to different water treatments and remediation approaches. The findings were published in npj Clean Water.
The research was conducted to better understand how PFAS chain length influences the chemicals' environmental fate, which could help water utilities and remediation projects select more effective treatment technologies and support the development of treatment systems tailored to the molecular structure of unique PFAS, rather than relying on one-size-fits-all strategies.
Short-Chain vs. Long-Chain PFAS
PFAS, often called "forever chemicals," are highly persistent in the environment and human body because of their strong carbon-fluorine bonds, making them resistant to degradation and leading to their bioaccumulation over time. According to the researchers, treating PFAS as a single class of contaminants may overlook important differences in how individual compounds move through water systems and respond to destruction and removal efforts.
Led by Hanyang University Professor Eilhann E. Kwon, Ph.D., the research team reviewed environmental, laboratory, and modeling studies comparing short-chain and long-chain PFAS. The review examined their physicochemical properties, environmental transport, and bioaccumulation. They also investigated removal by non-destructive treatment technologies such as activated carbon adsorption, ion exchange, and membrane filtration, as well as degradation using destructive treatment methods.
Short-Chain PFAS May Be More Problematic Than the Legacy PFAS They Are Replacing
The researchers found that long-chain PFAS generally bind more readily to sediments, organic matter, and biological tissues, increasing their potential to accumulate in the environment while also making them easier to capture using conventional treatment technologies. In contrast, short-chain PFAS remain more soluble in water, enabling them to travel farther through rivers, groundwater, and drinking water systems and making them more difficult to remove and degrade.
The findings are notable because many short-chain PFAS have been introduced as replacements for legacy long-chain compounds.
“Over the next five to ten years, this knowledge can support more predictive and customized water treatment systems that can capture and destroy a broader range of PFAS, including the short-chain compounds,” said Youn-Jun Lee, Ph.D., Hanyang University postdoctoral researcher and the study's first author. “Our work suggests that treatment strategies should be designed based on the molecular structure of PFAS, especially chain length."
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