MacIsaac, Sean

Sean MacIsaac was a speaker at the WEFTEC 2024 conference in New Orleans, LA October 5-9, 2024.

Titles from this speaker

Full-scale Comparison Between 280nm UV LEDs and Conventional 254nm Low-Pressure Disinfection

Abstract

Introduction: Ultraviolet LED technologies have progressed to the point where full-scale implementation is now on the horizon. The work outlined in this study is part of WRF project 5173 which investigates the feasibility of UV LEDs at different magnitudes of flow and water qualities. A 280nm, 100 GPM, closed-channel UV LED unit was installed in a wastewater facility in Nova Scotia, Canada to compare to a conventional open-channel UV disinfection system. This project represents the first ever installation of UV LEDs for wastewater disinfection at this scale and provides foundational data for understanding how UV LEDs scale as a technology. In addition, the practical experience gained during the installation process of this technology is valuable to consultants and utilities who may be considering the use of UV LEDs in the future. Project Background: Data was collected over a 4-month period before the installation of the full-scale UV LED system using the UV auditing approach. The UV auditing approach has been developed by Dalhousie University and provides an understanding of the delivered fluence for full-scale UV disinfection by leveraging bench-scale inactivation curves (Rauch et al., 2022). This approach has successfully demonstrated that UV LEDs can outperform conventional, mercury-based 254nm disinfection for some wastewater matrices (MacIsaac et al., 2023). UV auditing is also useful for utilities in understanding how LEDs will perform when considering mercury-free disinfection technologies. The LED reactor used for this work (shown in Figure 1) was manufactured by AquiSense Technologies and is a closed channel design with a 100 gallon per minute (GPM) capacity and was conducted over the Fall of 2023. The flow capacity of the LED unit represents approximately 10% of the average daily flow of the wastewater facility that it has been installed at. This installation marks the largest commissioning of a UV LED wastewater disinfection reactor anywhere in the world. Pre-installation data is shown in Figure 2 and was collected during the Summer of 2023. The average UV transmittance measured at the facility during this sampling period was 53% with an average power consumption of 35 KW. The disinfection results indicate that 280nm UV LEDs performed comparably to conventional 254nm low-pressure system and can provide sufficient pathogen inactivation when used at the full-scale. Additional Project Phases: The second phase of this work involves stress testing the UV LED reactor to define the range of performance in terms of power output, flow rate and UV transmittance. This work was conducted over a 4-week period in early 2024 and involved operating the reactor at a flow rate of 100 and 200 GPM, as well as power outputs ranging from 50-100%, and variable UVT during the sampling period. The final phase of this work involves the comparison between the UV LED reactor with the conventional, open channel, low-pressure UV system that is already installed at the facility. This work covers a 6-month period with twice weekly sampling of the inlet and outlet of both treatment trains. A scale analysis concludes this work by collecting samples of internal surfaces at the end of the six-month sampling period. This work identifies the differences in fouling mechanisms between each of the UV light sources. UV LEDs do not generate heat on the emitting side of the light source and therefore, are not expected to form inorganic scales in the same way that conventional mercury lamps do. This work provides foundational information for both consultants and utilities when considering approaches for testing the feasibility of using UV LEDs in wastewater facilities. UV LEDs have shown to be comparable in performance to conventional systems while avoiding several of the environmental, human health, and safety issues related to mercury-based UV disinfection. In closing, the tasks conducted in this work help achieve the goals in understanding UV LED implementation as defined in WRF 5173.

This study, part of a WRF project, assessed the feasibility of UV LED disinfection applications using real wastewater at scale. The reactor is equipped with 2 280nm UV LED panels, independently controlled to brighten, dim, or shut off during operation. A full-scale UV LED reactor was installed in 2024, tested at a variety of flow rates and power outputs. This work is the largest UV LED installation for wastewater to date and demonstrates the feasibility of this emergent technology.

SpeakerMacIsaac, Sean

Presentation time

11:00:00

11:30:00

Session time

10:30:00

12:00:00

SessionWhat's New in UV?

Session number518

Session locationRoom 238

TopicDisinfection and Public Health, Intelligent Water, Intermediate Level

Author(s)