Degradation of per- and polyfluoroalkyl substances in stormwater and secondary concentrated liquid from AFFF-impacted sources

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The widespread use of per- and polyfluoroalkyl substances (PFAS) has led to global contamination requiring innovative treatment needs to address the recalcitrant nature of PFAS. Traditional treatment techniques fail to degrade PFAS; separation and sequestration from the environment has been the main treatment, which produce a secondary waste stream requiring disposal. However, a concerted push from industry and the United States Department of Defense has focused on the development of destructive technologies. UV/SGM is a destructive treatment technology developed to degrade PFAS in concentrated liquid wastes. In this study, UV/SGM is challenged to treat synthetic ion exchange still bottoms, which consists of high concentrations of PFAS, salts, and total organic carbon. Two reactor configurations which were designed to combine photocatalytic and photolysis treatments in one system were assessed in this study. Total PFAS were degraded 81-91% from each reactor configuration and defluorination recovery varied from 72-92%. In addition, nitrate degradation and subsequent nitrite production during treatment were tracked over treatment time, and ultimately completely removed from the system. Dilute AFFF-impacted stormwater was also evaluated and yielded significant PFAS degradation and defluorination; however, full scale implementation is hindered by degradation rates. Results indicate that dilute wastewaters require longer contact time for PFAS degradation, making UV/SGM treatment impractical due to the sheer volume of dilute wastestreams requiring treatment. Concentrated wastestreams are the most practical field scale application of UV/SGM technology. Results further support the need for a sequestration and concentration technology followed by destruction treatment in a systems approach for PFAS.

9th International Congress on Environmental Geotechnics (ICEG2023)

Emerging Contaminants