Semester of Graduation

Spring 2023

Degree

Master of Civil Engineering (MCE)

Department

College of Civil and Environmental Engineering

Document Type

Thesis

Abstract

Ultraviolet disinfection has been used to treat water and wastewater for decades. Previous studies highlight the significance of disinfection conditions and attempt to model bacterial regrowth behavior according to disinfection dosing parameters. The emergence of light-emitting diode (LED) technology provides the ability to further explore bacterial repair methods after UV disinfection, which has been a growing concern within the UV community. However, it is necessary to also consider post-disinfection conditions to model the regrowth patterns of bacterial organisms more accurately. By varying reactivation wavelengths, and their respective intensities, experiments using Escherichia coli ATCC 15597 revealed how these parameters impact the reactivation in E. coli. The dosage of UVC light is a known factor in the organisms’ ability to repair damage to the DNA. However, variable regrowth conditions showed the intensity of reactivation light played a significant role in how E. coli recovered from UV damage, correlating to the growth rate constant of solar reactivation. The wavelength available during regrowth conditions (365 nm – 400 nm), also plays a significant role in bacterial repair abilities. Employing a chlorine co-dosing strategy allowed for a significant reduction in photorepair fractions. Accurately characterizing the regrowth parameters reduces the chances of overestimating pathogen removal rates at wastewater treatment plants, since factoring in different effluent conditions results in more accurate modeling techniques that can help calculate the effectiveness of UV treatment processes.

Date

3-30-2023

Committee Chair

Samuel Snow

DOI

10.31390/gradschool_theses.5760

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