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Masjoudi, Mahsa

University of British Columbia

Access to clean drinking water is a critical issue in many regions of the world due to rapid urbanization, population growth, and climate change. To address this challenge, potable water reuse has emerged as a viable solution, which involves recycling wastewater to produce high-quality drinking water using a multi-barrier approach including micro- or ultra-filtration, reverse osmosis (RO), and advanced oxidation processes (AOPs). As the final step of this process, AOPs play a crucial role by providing effective disinfection and elimination of micropollutants. Thus, enhancements in AOP technology further improve the quality of recycled water and make the reuse strategy more feasible for communities facing water scarcity. This research investigated the application of vacuum-UV (VUV) as an alternative AOP for treating micropollutants, 1,4-dioxane (1,4-D) and carbamazepine (CBZ), under potable reuse conditions. Kinetic studies were performed in various water matrices, accounting for the presence of monochloramine and free chlorine oxidants, as well as relevant operational parameters. VUV AOPs have the potential to achieve high treatment efficacy by directly breaking down water molecules at 185 nm, resulting in the generation of •OH. The addition of free chlorine or monochloramine individually hindered the removal of 1,4-D in the corresponding VUV AOPs. However, chlorination of chloramine-containing water significantly improved both the treatment performance and energy efficiency of the AOP. Additionally, the presence of water constituents such as bicarbonate, chloride, and organic matter reduced micropollutants degradation rates. Nevertheless, lower chloride levels were found to improve 1,4-D removal in the presence of free chlorine or chloramine oxidants by promoting the formation of Cl₂•-. In an actual RO permeate matrix, VUV AOPs demonstrated a superior treatment performance for 1,4-D removal compared to the conventionally used UV/H₂O₂ and UV/Cl₂ AOPs. Lastly, kinetic studies and modeling revealed that •OH and Cl₂•- species played a significant role in driving the degradation reactions in the VUV/Cl₂/Chloramine AOP. Overall, this study highlights the potential of VUV AOPs, particularly VUV/Cl₂/Chloramine, as an effective treatment technology for removing micropollutants from water and supporting potable reuse systems.

Text

2024-07-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85207

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/