Innovative UV-C LED Disinfection Systems for DrinkingWater Treatment

This paper describes the testing of two UV-C LED water disinfection pilot-scale units at the U.S. Environmental Protection Agency (EPA) Test and Evaluation Facility in Cincinnati, OH from December 2018 to October 2019. The pilot-scale testing included collimated beam testing and flow-through testing for both drinking water and municipal wastewater. The challenge test runs targeted MS-2 bacteriophage, total coliforms, heterotrophic plate count (HPC), Bacillus globigii, and Legionella in drinking water, and E.coli, Enterococci, total coliforms, HPC, and Bacillus globigii in municipal wastewater. The paper presents the results for MS-2 bacteriophage, total coliforms and HPC in drinking water.

I. Premise

Ultraviolet light of wavelength spectrum from 200 to 280 nanometer (nm)—UV-C light—has been used for several decades for disinfection applications and is well-established as a means of controlling microorganisms, specifically pathogens, in water because it can render microorganisms inactive by altering their DNA, and thus prevent microorganisms from replicating. Today, conventional UV water disinfection relies on mercury arc lamps where UV light is generated by flowing electrons from an electrical source through ionized mercury vapor. Mercury is contained within these UV lamps and, for safety reasons, is isolated from exposure to water by the lamp envelope and the surrounding lamp sleeves.