A novel reactor design has been created for use in destroying PFAS in water or in concentrate.
The treatment of drinking water is often accomplished by stripping the PFAS from the water using a suitable adsorbent such as activated carbon or another adsorbent with the appropriate selectivity. However, this can be a short-term solution as the adsorbent must be either regenerated or discarded, which may allow environmental recontamination at a future time. Disposal of unused aqueous fire-fighting foam (AFFF) presents an even more significant problem because the amount of material in the concentrate is approximately 3-6% making it a potential source for future environmental contamination. Therefore, there is a pressing need to develop water and wastewater treatment processes and AFFF destruction methods that are efficient, cost effective, and scalable.
The envisioned method would destroy the PFAS and potentially many other contaminants. A reactor design has been developed that performs the adsorption of a target compound while simultaneously regenerating the adsorbent. The reactor addresses several constraints in commonly proposed reactors. The degradation process occurs in two steps where the first entails adsorption of the PFAS compound onto a photocatalytic material and the second step involves illumination with activating light to produce oxidizers which mineralize the PFAS material. As with any multiphase reaction, it is critical to provide a means of effectively contacting the solid particles of photocatalytic material with the reactants in order to efficiently perform a good conversion. Barriers to good conversion and efficient scaling of PFAS destruction reactors include the ability to simultaneously provide sufficient mass transfer surface area and sufficient illumination of the photocatalytic material by which strong oxidizing species are produced which ultimately react with and destroy PFAS.
The reactor design, in which adsorption and photo-catalytic degradation processes are decoupled which allows resources to be allocated to each portion of the system independently and for ready scaling of the process. The reactor system is based on a fluid-particle contact system that provides maximum process flexibility and efficiency. Preliminary process calculations predict the amount of energy needed to destroy PFAS molecules could be less than 20% of thermal destruction methods.
(1) treatment of drinking water
(2) treatment of wastewater and manufacturing waste streams
(3) destruction of existing inventories of aqueous firefighting foam (AFFF) concentrate
(4) PFAS, PFOA and possibly other contaminants such as dioxane
- Destroys PFAS – The regeneration process is designed to decompose the PFAS or a target compound into minerals such as water, carbon dioxide, fluoride (F-) ions, phosphate (PO43-) and sulfate (SO42-) ions.
- Scalable – Decouples the adsorption and decomposition steps to provide a means to individually optimize the process.
- Decoupled adsorption and regeneration processes allows resources to be allocated to the portion of the process that is the bottle neck.
- The same method can be used for other compounds that can be adsorbed and decomposed photocatalytically.
Benefits: Destroys PFAS without incineration.
Patents and Licensing: U.S. National Phase Application No.: 18/249,671
Key Words: PFAS, PFOA, dioxane, aqueous firefighting foam (AFFF), water treatment
Robert Gallo Director Intellectual Property & Licensing