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UBC Theses and Dissertations

Development of a point-of-entry UV-LED water disinfection reactor Mohaghegh Montazeri, Mahyar


UV-LED is a new source of UV radiation that is proposed as an alternative to conventional mercury lamps for water disinfection applications, as it has several advantages such as wavelength diversity, instant on/off ability, and being mercury-free. However, one of the main challenges along the path to adopting this technology is the requirement for novel reactor designs that are able to fully harness UV-LED radiant power. In this study, one of the first high-flow point-of-entry (POE) UV-LED water disinfection reactors was designed, fabricated, and characterized in lab and field conditions. A multiphysics computational model was developed to predict the performance of UV water disinfection design concepts by modelling the synergic effect of radiation, hydrodynamics, and kinetics of microorganisms’ inactivation. The geometrical optics method was employed to model the radiation profile of UV LEDs in complex reactor geometries. The model was used for virtual prototyping of the POE UV-LED water disinfection reactor, and the performance of various optical and hydrodynamic design strategies was investigated. The optimum design, which employed 14 UV-LEDs assembled over custom-made optical modules, was characterized in the lab by measuring its radiation profile, residence time distribution (RTD), and biodosimetry in various flow rates and UV transmittance (UVT) conditions. The system resulted in a reduction equivalent dose (RED) of 65 mJ/cm² at a flow rate of 20 L/min while consuming 53.4 W energy. The last stage of this study was field testing the reactor by connecting it to the secondary effluent of a wastewater treatment plant. The low UVT (55%–64%) and high turbidity (4–10 NTU) considerably affected the performance of the system. Fouling consisting of minerals, such as iron, calcium, and zinc, was observed over the reactor walls. The results and insights provided in this study can pave the way toward the development of efficient large-scale UV-LED water disinfection reactors for municipal and industrial water disinfection applications. The discussions will be particularly beneficial for scientists and research and development (R&D) professionals who work toward the design of optimum flow through UV-LED water disinfection reactors using numerical tools.

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