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Innovative UV-C LED Disinfection Systems for Drinking Water Treatment
Citation:
Vairamohan, B., G. Hunter, C. Arzbaecher, R. Ehrhard, J. Goodrich, AND J. Hall. Innovative UV-C LED Disinfection Systems for Drinking Water Treatment. In Proceedings, 8th IEEE Conference on Technologies for Sustainabilty (SusTech 2021) - Virtual, Cincinnati, OH, April 22 - 24, 2021. IEEE, New York, NY, 20777838, (2021). https://doi.org/10.1109/SusTech51236.2021.9467430
Impact/Purpose:
In much the same way that visible light emitting diodes (LEDs) have revolutionized the general lighting industry, UV-C LEDs are now viewed as the “next generation” in UV-C disinfection and are expected to rapidly replace conventional mercury arc lamps in water disinfection applications. LEDs are made from crystalline compound semiconductors that emit light when energized. UV-C LED system integrators purchase many single-packaged UV-C LEDs and combine them into a larger UV-C LED reactor which is then equipped with electronics, thermal management system, optics, and housing to create a finished UV-C LED system or module. Point-of-use (POU) UV-C LED systems for the treatment of potable water are already commercially available and market competitive, but larger-capacity UV-C LED systems for municipal water and wastewater disinfection are still under development. While it is generally accepted that UV-C LED technology can be scaled up, its performance must be verified and scale-up factors must be determined before technology transfer to the high-throughput levels of municipal water/wastewater systems and industrial-scale water reuse applications can occur.
Description:
The primary objectives of this project were to evaluate the disinfection performance, reliability, and energy use requirements of two small-scale UV-C LED water disinfection units (e.g., 10 gallons per minute (gpm) rated sizes) for a variety of test conditions. Test conditions included treating water to achieve public supply drinking water, municipal treated secondary wastewater, combined sewer, and reuse water requirements. The experiments assessed the capability of UV-C LED technology to disinfect a continuous flow of water containing MS-2 bacteriophage (or MS-2 in short) as the surrogate contaminate along with E. coli, and total coliforms. Analytical testing was conducted by US EPA using procedures identified under 40 Code of Federal Regulations (CFR) part 136. The pilot-scale test results indicate UV-C LED technology can achieve similar log removals to conventional mercury vapor lamps for MS-2, total coliforms, and HPC in drinking water. Specifically, flow-through test results for the two UV-C LED pilot units show a 2-log to 3-log removal of the surrogate contaminate MS-2 in drinking water at UV doses of 40 to 50 mJ/cm2. These results are very promising. As a next step, the project team recommends full-scale demonstrations with larger UV-C LED water disinfection systems to evaluate the viability of treating drinking water in smaller communities. Data from full-scale demonstrations would help validate operational and maintenance parameters. Such demonstrations would benefit from side-by-side testing of conventional mercury vapor lamp systems.
