Sequenced Combination of UV LED Wavelengths for Enhanced Inactivation of Waterborne Pathogens

EPA Grant Number: SU835716
Title: Sequenced Combination of UV LED Wavelengths for Enhanced Inactivation of Waterborne Pathogens
Investigators: Elliott, Mark , Kung, Patrick
Institution: University of Alabama
EPA Project Officer: Lank, Gregory
Phase: I
Project Period: August 15, 2014 through August 14, 2015
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2014) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Water , P3 Awards , Sustainability

Objective:

Ultraviolet (UV) light-emitting diodes (LEDs) are an emerging, energy efficient and environmentally benign alternative for disinfection of waterborne pathogens. UV LEDs are commercially available that can generate narrow-spectrum emission in a range of UV-A and UV-C wavelengths and deep UV LEDs (<240 nm) are in development. These wavelengths inactivate microorganisms by different mechanisms, and their combination could potentially lead to greatly enhanced treatment effectiveness. Despite the potential advantages of UV LEDs, many questions remain.

This project will test the effectiveness of three UV LEDs (255-, 280- and 362-nm peak emission) and a 225-nm laser for inactivation of bacterial and viral indicators of UV treatment effectiveness. Wavelengths will be evaluated for efficiency in inactivating bacterial and viral indicators individually, and also in sequenced pairs. We propose that the combination of multiple inactivation mechanisms, particularly the novel addition of protein destruction by 225-nm emission, can yield improved performance. Our immediate objectives are to evaluate the efficacy of these four wavelengths, individually and in combination, with the goal of informing design of UV LED treatment units.

Approach:

Water and wastewater treatment and reuse using UV LEDs promises many advantages over other disinfection methods: energy efficiency, weight, portability, no toxic waste, no disinfection by-products (DBPs), low heat generation, and potentially very low cost. This project will enhance understanding of UV LEDs, the potential of deep UV, and the benefits of combining UV wavelengths. Creating UV LED treatment devices will benefit people by protecting them from waterborne disease and the DBPs generated by chemical disinfectants. The low cost relative to conventional UV and reduction of lost work time from waterborne disease will benefit prosperity. Eliminating hazardous mercury waste and reducing carbon emissions through energy efficiency will benefit the planet.

Student team members include graduate and undergraduate students pursuing degrees in drinking water treatment and electrical engineering. If funded, this project will be pursued for thesis research by at least two students on the team; it will supplement the research experience of the two other team members.

The PI plans to integrate a UV LED disinfection module into a new lab-based course through a two-three week lab and lecture module. The module will include evaluation of treatment efficiency, and the sustainability and pollution prevention benefits of the transition from mercury lamps to LEDs.

Expected Results:

Expected outputs from this work include evaluation of the effectiveness of four UV wavelengths, individually and in sequenced combination. Wavelengths and microbial indicators to be tested in this project have been chosen to target specific gaps in the scientific literature, which will lead to publication. Outcomes include the preliminary design of UV LED treatment devices.