Evaluation of the degradation of per- and polyfluoroalkyl substances (PFAS) using UV-activated silica-based granular media (UV/SGM)
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Abstract
Per- and polyfluoroalkyl substances (PFAS) have become ubiquitous in the environment through production, industrial use, and consumer use. PFAS are recalcitrant, persistent, and bioaccumulative contaminants of concern which are present in many solid and liquid sources. PFAS have been detected in surface water, groundwater, drinking water, wastewaster, landfill leachate, soils, sediments, and sludge, along with other impacted medium. The Environmental Protection Agency (EPA) has begun developing analytical standards, advisories, and regulations to deal with the cleanup of PFAS. Many field implemented treatment technologies sequester or separate PFAS from the bulk liquid or solid, however, secondary concentrated waste is produced. Landfilling concentrated PFAS waste causes additionally exposure pathways through landfill leachate, which can migrate into groundwater, and eventually back to drinking water. Breaking down the recalcitrant fluorinated organics into inorganic species allows for mitigated risk during treatment and minimizes long-term exposure pathways. Ultra-violet activated silica based granular media (UV/SGM) was developed to break down PFAS into non-harmful inorganic species within concentrated wastes. UV/SGM operates as a packed bed column reactor which allows PFAS to adsorb to the photocatalytic media and subsequently degrade through the production of reactive species under the presence of UV light. Validation of UV/SGM to degrade PFAS in reagent grade PFAS spiked solutions and in environmentally relevant waste streams was evaluated over four studies presented in this dissertation. UV/SGM was able to degrade more than 10 PFAS >99%, with some more recalcitrant PFAS requiring longer treatment periods. Aqueous fluoride was tracked over each treatment experiment, with >90% defluorination achieved in environmental solutions. UV/SGM is demonstrated to be effect in reagent and complex matrices, energy efficient, easy to scale, and modular, allowing for end users needs to not only be met but exceeded, mitigating PFAS in the environment.
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Introduction -- Degradation and defluorination of aqueous perfluorooctane sulfonate by silica-based granular media using batch reactors -- Coupled photocatalytic alkaline media as a destructive technology for per- and polyfluoroalkyl substances in aqueous film-forming foam impacted stormwater -- Development and laboratory scalability of ultraviolet (UV) activated silica-based granular media (SGM) as an engineered system for the degradation of per- and polyfluoroalkyl substances (PFAS) in concentrated liquid waste -- Treatment of per- and polyyfluoroalyl substances in regenerable ion exchange still bottoms using UV-activated silica-based granular media (UV/SGM) as a destructive technology -- Conclusion and recommendations for implementation
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Ph.D. (Doctor of Philosophy)