UV-based and Ion Exchange Technologies for Drinking Water Treatment Applications

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Natural organic matter (NOM) and nitrate are among the constituents of surface water causing concern and affecting treatment processes. NOM is known as a primary precursor for chlorinated disinfection by-products. Also, it causes membrane fouling, reduces the aesthetic quality of water, and leads to deterioration of biological stability of water. Under the application of ultraviolet (UV)-based advanced oxidation processes (AOPs) to surface water for the removal of micropollutants, NOM scavenges hydroxyl radicals and screens UV, thereby reduces the overall efficacy of the treatment applied. Nitrate in raw water is an anion of health concern if it exceeds the regulations. Moreover, nitrate can be converted to nitrite (a more serious health concern) during the application of certain UV-based AOPs. Therefore, improving the water quality upstream of the UV-based AOPs is of interest and could lead to improved performance and reduced energy consumption. Ion Exchange (IEX) treatment process could be utilized as the primary barrier in a treatment train to remove NOM and nitrate simultaneously. The application of IEX has the potential to improve water quality undergoing further treatment with AOPs used for the removal of trace concentration of micropollutants. That said, studies have shown the presence of inorganic anions to interfere with NOM removal, thus reducing the overall efficacy of the IEX process. The main objective of the proposed research program is to develop and address fundamental challenges of applying IEX as well as UV-based AOPs to water treatment. Special emphasis will be given to developing and evaluating fluidized bed IEX reactors along with their combinations with UV-based AOPs. In addition, this proposal intends to address some fundamental and engineering issues related to the impact of IEX and UV-based AOPs on water quality. These overall goals will be achieved by focusing on three specific and highly important sub-objectives: 1. Develop and study fluidized bed IEX process and evaluate various design criteria 2. Investigate the impact of IEX process on the efficacy of UV-based AOPs at removing model micropollutants by improving the upstream water quality 3. Study the profile of water quality throughout the combined IEX and UV-AOPs 4. Study the fate of nitrogenated byproducts during the combined IEX and UV-AOP treatments. Each of the above sub-objectives will be achieved through extensive laboratory experiments along with modeling and theoretical analysis. All these will lead to the development of efficient technologies will contribute significantly to improving health, quality of life, and the environment in Canada. It will have beneficial impacts among the engineering and scientific communities, since it represents a fundamental approach to the development and application of such integrated technology.