POSTPONED Dissertation Defence: Ultraviolet Disinfection of Unfiltered Water Supplies: Exploring Effects of Particle-Microorganism Association and Efficiency Enhancement Strategies

Mehrnaz Soleimanpour Makuei, supervised by Dr. Nicolas Peleato, will defend their dissertation titled “Ultraviolet Disinfection of Unfiltered Water Supplies: Exploring Effects of Particle-Microorganism Association and Efficiency Enhancement Strategies” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering.

An abstract for Mehrnaz Soleimanpour Makuei’s dissertation is included below.

Examinations are open to all members of the campus community as well as the general public. Please email nicolas.peleato@ubc.ca to receive the Zoom link for this defence.

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ABSTRACT

Traditional water quality indicators used in water treatment facilities have limitations in assessing particle-microorganism interactions and treatment system performance under challenging conditions. This study seeks to explore the impacts of particle-microorganism interactions on ultraviolet (UV) disinfection performance, identify water quality indicators that best describe performance, and suggest simple methodologies to mitigate the effects on disinfection performance.
Several sampling points of two full-scale treatment plants without filtration were monitored for a year to identify the impacts of particulates on UV performance. The research established a significant link between zeta potential, and UV disinfection effectiveness, surpassing conventional water quality indicators. A comprehensive examination of methods for detecting particle-microorganism associations was conducted to devise an experimental approach in line with contemporary research directions and supported by a strong theoretical foundation.
To further explore the impact of challenging source water conditions on UV disinfection, the second objective was to study a wide variety of water quality conditions. Results suggested that UV disinfection could be compromised even at low turbidity levels (< 1 NTU), depending on the particulate type present. Furthermore, complex interactions with background source water quality and additional particulates were observed and suggested that non-specific indicators (turbidity ot UVT) should be used with caution when predicting the UV performance under challenging conditions. Overall, the measurement of zeta potential enhanced UV disinfection predictability.
The observed influence of zeta potential on UV performance led to proposing a UV enhancement strategy. A new line of study was started to identify if manipulating particle-microorganism associations through targeted zeta potential modifications was viable as disinfection enhancement strategy. Assessing zeta potential manipulation effects on water quality using bacterial and viral surrogates showed that samples with highly negative zeta potential result minimal particle-microorganism associations, increasing UV disinfection efficacy. It was concluded that zeta potential manipulation could be a practical and cost-effective UV pre-treatment method appropriate for systems without adequate pre-treatments.
In summary, this research highlights the limitations of conventional indicators in assessing UV disinfection in challenging conditions. Zeta potential emerged as a key factor in improving UV assessment, providing a novel approach for treatment facilities’ design, especially evolving water quality scenarios.