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Adeyeye, Adepeju Adefolawe

University of British Columbia

Ultraviolet (UV) disinfection has long been employed to inactivate pathogens in water, but scaling and fouling on UV disinfection lamp quartz sleeves pose significant limitations, diminishing disinfection effectiveness. Common UV water disinfection systems include conventional mercury pressure UV lamps and UV light-emitting diodes (LEDs). Literature suggests that UV LEDs exhibit potential advantages over conventional mercury pressure lamps, being less susceptible to scaling; however, this has not been tested. This study compared the impact of iron, manganese, magnesium, and calcium on the ultraviolet transmittance of quartz glass. In terms of scaling formation on quartz glass, iron had the most impact, followed by manganese, magnesium, and calcium. Lime and lemon juice were efficient in removing scaling due to calcium and magnesium, but could not reverse scaling caused by manganese and iron. This study also compared the susceptibility of a conventional low-pressure (LP) UV system (PURA Water Products, LLC) and a UV-C LED (Crystal IS, an Asahi Company) system to scaling formation. Simulating varying hardness levels using calcium carbonate revealed increased hardness deposition and a decline in UV fluence at the optimal flow rate. Lime and lemon juice were tested as alternatives to citric acid for removing scaling on the quartz sleeves/windows. As water hardness concentration rose, both systems experienced escalated hardness deposition and effluent turbidity. Although the observed hardness deposition was similar, the LP UV system exhibited deposition mainly in the reactor and significant amounts on the quartz sleeve, while the UV-C LED system had minimal deposition in the reactor and on the quartz window. Subsequently, both systems showed a decline in fluence after scaling, with LP UV experiencing a higher percentage fluence decline. Lime juice effectively removed scaling in the LP UV, and lemon juice worked for the UV-C LED after determining the optimal cleaning time for each system, as both cleaning agents were found to have similar cleaning power on the reversal of calcium scaling.

Text

2024-03-05

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87522

Civil Engineering

University of British Columbia

UBCV

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