EXPLORING EMERGING ULTRAVIOLET LIGHT EMITTING DIODES FOR WASTEWATER DISINFECTION

Abstract

Ultraviolet Light Emitting Diodes (UV LEDs) are an emerging technology in the water industry that offer the potential to deliver substantial benefits over the conventional mercury-based technology. A comprehensive literature review of UV LED technology and its use in the water and wastewater sectors showed that there is a large wavelength dependence in treatment that can be highly species dependant. In this thesis, a new method was developed to benchmark the performance of a full-scale UV disinfection reactor by comparing its performance to collimated beam testing at the bench-scale. This method was then applied to estimate the performance of UV LED technologies in a real wastewater matrix. These groundbreaking experimental data showed that UV LED technologies using 280 nm wavelengths outperformed the standard 254 nm wavelength of mercury based systems and had the potential to be more energy efficient as the LED technology matures. Finally, the impacts that wastewater contaminants have on different wavelengths’ efficacy of treatment was explored, and various impacts by the wastewater matrix were observed. Further investigation is required to understand the underlaying mechanisms. Overall, this work has shown that UV LED technologies are a viable option for municipal wastewater treatment facilities; however, wavelength selection will be crucially important to ensure the most efficient treatment for a given facility.