UBC Theses and Dissertations

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UBC Theses and Dissertations

Fate of chlorine in indoor swimming pools : a numerical modelling approach Mahinpour, Pedram


Swimming is one of the most popular recreational activities around the world. The interactions and activities of bathers during swimming may introduce contaminants which can lead to serious infections and health issues. There are a number of different techniques currently used to improve the sanitation in swimming pools. Some of the disinfectants commonly used in swimming pools include chlorine ozone and UV radiation. Chlorination is popular because it is simple, affordable and has residuals, but there is evidence that it may pose risks to human health as chlorine reacts with organic and inorganic matter in the water which generates disinfection by-products (DBPs). Extensive research has been performed on the kinetics of DBPs formation, and on the fate of chlorine in swimming pools. However, the effects of hydraulics in swimming pools have not been given the same level of attention. This thesis focuses on examining the fate of chlorine based on hydraulic behaviour in swimming pools using computational fluid dynamics (CFD) approach. Three different scenarios have been studied to estimate the effects of inlet size on the distribution of chlorine in indoor swimming pools. The spatial distribution of chlorine and the mixing rates for chlorine are known to be significantly affected by the inlet size. In all three selected scenarios, after a period of two hours, the average concentration of chlorine in the swimming pool reached a constant level of approximately 60% of the maximum injected concentration. The simulation results suggest that, while the mass flow rate is constant, a smaller inlet size provides better mixing rates. The chemical reaction of chlorine with ammonia has been examined using random releases to mimic urine release in swimming pools. The results show that significant amounts of ammonia may not react with chlorine. Chlorine available for the reaction was found to be far less than the required amount. This research contributes towards improved understanding of the chlorination process in swimming pools. This research guides an improved indoor swimming pool design that can ensure better chlorine distribution and reduced DBPs formation, and thereby reduced human health risks.

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