Pilot wastewater system destroyed more than 99% of PFAS in concentrated foam
A two-stage treatment process captured long-chain PFAS from 60,000 liters of wastewater before treating the concentrated residue with high heat and alkaline conditions.
Editorial illustration — not from the study.
Researchers tested a continuous-flow treatment train on 60,000 liters of sludge dewatering pressate from a municipal wastewater treatment plant. The first stage used bubbles to move PFAS into a concentrated foam, while the second applied high temperature and high pH to treat the foam.
The bubble-based stage completely removed the long-chain PFAS PFOS and PFOA and removed 78% of total measured PFAS under the best-performing conditions. It produced about one gallon of concentrated waste for every 490 gallons of water treated. The second stage achieved more than 99% total measured PFAS destruction and removal in that concentrated material under the best-performing conditions.
What the pilot system found
The study evaluated two continuous-flow systems operated as a sequential treatment train at pilot scale. The first stage, foam fractionation, used air to separate PFAS into a concentrated foam. Long-chain PFAS such as PFOS and PFOA were completely removed, while total measured PFAS removal reached 78% under the best-performing conditions.
The concentrated foam represented a waste product equivalent to one gallon for every 490 gallons of water treated. The second stage, hydrothermal alkaline treatment, used high temperature and high pH. Under the best-performing conditions, it achieved more than 99% total measured PFAS destruction and removal in the concentrated foam.
Why the treatment matters
Municipal wastewater treatment plants receive PFAS from household and industrial sources, and these compounds can accumulate in biosolids or remain in treated liquid. Treating them is difficult because wastewater flows are large, PFAS concentrations are often low, and the water contains many other substances.
This pilot study indicates that combining a process that concentrates PFAS with a process that treats the smaller resulting waste stream can address both parts of the problem. The results also show that long-chain PFAS can be removed from the tested wastewater stream and that the concentrated material can then undergo substantial PFAS destruction and removal.
Evidence and limits
The evidence comes from a pilot-scale demonstration using 60,000 liters of sludge dewatering pressate in a municipal wastewater treatment setting. The reported results were achieved under the best-performing conditions, and the percentages refer to total measured PFAS rather than every PFAS compound that might be present.
The abstract does not establish how the system would perform with other wastewater streams, at full plant scale, over longer operating periods, or for PFAS not captured by the measurements. It also reports the foam fractionation and hydrothermal alkaline treatment results separately within the treatment train, rather than providing a broader assessment of overall plant operation or costs.
// Source
ACS ES&T Water · 2026 · DOI: 10.1021/acsestwater.6c00947
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