UV LEDs for Wastewater Disinfection
Bailey Reid (Dalhousie University)

Drinking water and wastewater treatment facilities rely on disinfection systems to provide properly treated water for drinking and reuse respectively. An emerging disinfection treatment process for wastewater treatment is using UV LEDs instead of conventional mercury ballasted UV sources. This project explores the feasibility of UV LEDs as an appropriate technique for full-scale wastewater disinfection. A 280nm, 100 gpm closed-channel UV LED reactor was installed in a wastewater facility in Atlantic Canada. The disinfection performance of the instrument was assessed using UV auditing pre and post installation in the wastewater facility. UV auditing was done by comparing collimated beam dosimetry with twice weekly full-scale sampling to assess the performance of UV LEDs compared to conventional UV disinfection. Pre-installation data clearly indicated that UV LEDs perform comparatively to conventional UV sources and is in alignment with previously published work from Dalhousie. Stress testing of the UV LED reactor was also performed where flow and various power outputs were used to benchmark the boundary flows, UV transmittance, and water qualities. Identifying the performance of the UV LED as compared to the conventional system is a key outcome of this work and will aid utilities in their decision making when retrofitting and upgrading facilities. The elimination of mercury from full-scale systems is a potential environmental boon in terms of improving the inherent safety and One Water performance.