Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7d. Ex Situ PFAS Water Treatment Technologies

Formatted Title:

Innovative Foam Fractionation Technology for the Treatment of Per- and Polyfluoroalkyl Substances (PFAS) in Contaminated Water Using Biodegradable Amendments

Background/Objectives:

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made refractory compounds that are widely used in a variety of industrial and commercial products since the 1940s, leading to contamination of groundwater and surface water systems. They are persistent, bioaccumulative and toxic chemicals. Foam fractionation is a potential remedial technique for treating PFAS-contaminated water, taking advantage of the high surface activity to remove them from the solution by adsorption onto the surface of the air bubbles. Nevertheless, traditional foam fractionation technology developed for PFAS is challenging and found to be difficult to use on field leading to the use of additives either to increase foaming capacity or PFAS extraction. Different chemicals were the subject of investigation as surfactants to achieve better removal. However most surfactants are toxic, expensive and/or require post treatment after use. To meet this challenge, SPUMA has developed and patented a more cost-effective, biodegradable, and environmentally friendly biological additive. This additive operates in two distinct ways: I) it binds with high affinity to PFAS, and II) it promotes the foam formation, making it easier to extract.

Approach/Activities:

To achieve this, lab work has been undertaken since 2020 on spiked waters to identify the best additive. Additional trials have conducted on AFFF-laced waters from the Lubrizol fire (Rouen, France, September 2019), highly contaminated by PFOS and PFOA. In addition a pilot-scale trial was conducted with existing foam fractionation units and a continuous flow of 50 m³/H custom unit on both spiked waters, leachate, and waters from a Normandy wastewater treatment plant containing PFBA, PFOA, and 6:2 FTAB.

Results/Lessons Learned:

This dual-action mechanism allows for a faster and, more importantly a more effective PFAS extraction with removal rates of 99,9% for all for all PFAS with a carbon chain longer than C7, PFHxS, PFPeS, and 98% for PFHxA and PFBS under specific conditions. However, a lower removal rate is observed for short and ultra-short-chain carboxylic compounds, ranging from 15 to 52% for PFBA and PFPeA, depending on various treatment parameters (flowrate, bubble size, bubbling gas, various chemical parameters…).

Similar removal rates were observed both on units designed specifically for this additive or on existing foam fractionation units. On these units, the trials conducted in collaboration with ENVYTECH and ALLONNIA highlighted a processing reduction time ranging between a factor of 1.5 to a factor of 3.

In sum, the advantages of the Bio Foam Fractionation presented a low-waste production, a cost and energy efficient operation and a use of a biodegradable additive requiring no separation step after treatment, nor any post treatment. Coupled with these first findings, this suggest that the Bio Foam Fractionation process is a highly applicable treatment technology for PFAS contaminated waters. Additional investigations are currently carried out in order to optimize the process and establish a strategy for an integrated solution to degrade PFAS in concentrates.

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Stanislas wojewodzki