What are ultra-short-chain PFAS and why are they concerning in drinking water?

Ultra-short-chain PFAS are per- and polyfluoroalkyl substances with very short carbon chains (C2–C3), including trifluoroacetate (TFA). They are highly water-soluble, mobile, and ubiquitous in drinking water sources globally, making them difficult to contain and remove. Their prevalence and resistance to conventional treatment pose a significant challenge for water purification.

What is the most effective way to remove ultra-short-chain PFAS from drinking water?

Reverse osmosis (RO) and nanofiltration are the most effective technologies for removing ultra-short-chain PFAS from drinking water. These advanced membrane separation processes can achieve over 90% rejection of these challenging contaminants, which are resistant to conventional methods like activated carbon. AMPAC USA designs and manufactures industrial RO systems specifically for such demanding purification needs.

Why are ultra-short-chain PFAS harder to treat than other PFAS compounds?

Ultra-short-chain PFAS are more water-soluble and mobile than their longer-chain counterparts, making them resistant to common treatment methods like activated carbon. Additionally, standard 'PFAS total' parameters such as adsorbable organic fluorine (AOF) and total oxidizable precursor (TOP) assays often fail to capture their presence, leading to an incomplete picture of contamination.

Which specific ultra-short-chain PFAS are most commonly found in drinking water sources?

The ultra-short-chain PFAS trifluoroacetate (TFA), perfluoropropanoate, and trifluoromethanesulfonate are ubiquitous and found at the highest concentrations in drinking water sources. In German samples, these compounds alone constituted 98% of the sum target PFAS concentrations, highlighting their widespread presence.

Are ultra-short-chain PFAS currently regulated in drinking water?

Ultra-short-chain PFAS are largely unregulated, despite their prevalence and persistence. While there is a shift in Europe towards a broader PFAS group regulatory approach, specific regulations for these ultra-short-chain compounds are still developing. This lack of regulation underscores the need for preventive measures and advanced treatment solutions like reverse osmosis.

Ultra-Short-Chain PFASs in the Sources of German Drinking Water: Prevalent, Overlooked, Difficult to Remove, and Unregulated

Sammy FaragAMPAC USA — August 1, 2022

Ultra-Short-Chain PFASs in the Sources of German Drinking Water: Prevalent, Overlooked, Difficult to Remove, and Unregulated

By Sammy Farag . August 1, 2022

Quick Answer: Ultra-short-chain PFAS (C2–C3 carbon chain, including trifluoroacetate/TFA) are detected at significant concentrations in German and global drinking water sources. They are more water-soluble and mobile than longer-chain PFAS, resistant to conventional treatment including activated carbon, largely unregulated, and persistent in the environment. Reverse osmosis and nanofiltration are the most effective removal technologies, achieving >90% rejection of these challenging contaminants.

Abstract

Per- and polyfluoroalkyl substances (PFASs) have been a focal point of environmental chemistry and chemical regulation in recent years, culminating in a shift from individual PFAS regulation toward a PFAS group regulatory approach in Europe. PFASs are a highly diverse group of substances, and knowledge about this group is still scarce beyond the well-studied, legacy long-chain, and short-chain perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs). Herein, quantitative and semiquantitative data for 43 legacy short-chain and ultra-short-chain PFASs (?2 perfluorocarbon atoms for PFCAs, ?3 for PFSAs and other PFASs) in 46 water samples collected from 13 different sources of German drinking water are presented. The PFASs considered include novel compounds like hexafluoroisopropanol, bis(trifluoromethylsulfonyl)imide, and tris(pentafluoroethyl)trifluorophosphate. The ultra-short-chain PFASs trifluoroacetate, perfluoropropanoate, and trifluoromethanesulfonate were ubiquitous and present at the highest concentrations (98% of sum target PFAS concentrations). “PFAS total” parameters like the adsorbable organic fluorine (AOF) and total oxidizable precursor (TOP) assay were found to provide only an incomplete picture of PFAS contamination in these water samples by not capturing these highly prevalent ultra-short-chain PFASs. These ultra-short-chain PFASs represent a major challenge for drinking water production and show that regulation in the form of preventive measures is required to manage them.

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Source: Water Feed