ARFF NEWS (CONT)
(A) Removed and destroyed 20 times more PFAS in less than 48 hours compared to single water rinse. Tap water was recirculated at 25 gpm between the PFASigator and the firetruck for multiple hours. Table 1 shows that the total PFAS released from the primary tank in this single water rinse reached a concentration of 1.8 milligrams per liter (mg/L or parts per million (ppm)) (Phase 1). Adding surfactant only to the recirculating water did not significantly impact PFAS desorption (Phase 2). However, activating the PFASigator® in the recirculation loop with the primary tank (Phase 3) resulted in continuously increasing concentrations of fluoride in solution, indicating continuous destruction of PFAS well beyond the equivalent destruction of 1.8 mg PFAS/L, the amount measured in the single water rinse. A plateau in fluoride production and PFAS destruction was reached within 48 hours (Figure 3). Final fluoride measurements confirmed that a total of 16.8 grams (g) PFAS were removed and destroyed in the PFASigator- firetruck recirculation loop. This is 20 times greater than the 0.8 g PFAS removed from the single water rinse. Similar results were produced for the AFFF secondary tank within 24 hours. A combination of co-occurring PFAS destruction and rinsewater recirculation, and elevated water temperature (40 – 50°C) contributed to continuous PFAS removal from the truck and improved overall truck cleanout performance.
Figure 3 – Time series of fluoride production during PFASigator operation (Phase 3) as a direct indicator of PFAS destruction. (B) Limited amount of water used for firetruck decon with no off-site disposal. Once connecting the PFASigator and firetruck in the recirculation loop, PFAS destruction and desorption occurred in a single step. This setup helped to minimize water use. The amount of water used was equivalent to the volume needed to fill the system only once (approximately 120 gallons). Also, the recirculation loop was conducted at neutral pH, atmospheric pressure, and a temperature not higher than 50°C, thereby posing no concerns for damage to system interiors. (C) No off-site disposal and no toxic byproducts generated from the PFAS destruction process. Upon completion of the PFAS destruction phase (Phase 3), the treated recirculation solution was polished via a small filtration vessel to remove the trace PFAS remaining in the water (Phase 4). As shown in Table 1, PFAS concentrations were non- detect at <2.1 parts per trillion (ppt) in the filtered water, providing a variety of options for the final water disposal. The filtered water was also analyzed for metals, TOC, and several potential byproducts. Results demonstrated that no products of concern were generated from the treatment process. Additionally, the trace amount of PFAS captured on the filter can be washed off the filter once it is saturated and further destroyed by the PFASigator.
Table 1 – PFAS concentrations during demonstration phases.
(C) PFAS rebound after 12 days was at low ppb levels.
14 MAY- JUNE 2025 | ARFF NEWS
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