title: Microbial UV fluence-response assessment using a novel UV-LED collimated beam system.
abstract: A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms.
authors.affiliation: Hazen and Sawyer, P.C., 4944 Parkway Plaza Blvd., Suite 375, Charlotte, NC 28217, USA. ckbowker@gmail.com
authors.forename: Colleen
authors.initials: C
authors.lastname: Bowker
authors.forename: Amanda
authors.initials: A
authors.lastname: Sain
authors.forename: Max
authors.initials: M
authors.lastname: Shatalov
authors.forename: Joel
authors.initials: J
authors.lastname: Ducoste
mesh_terms: D017123:Bacteriophage T7 / Q000254:growth & development / Q000528:radiation effects; D004203:Disinfection / Q000295:instrumentation* / Q000379:methods; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000254:growth & development / Q000528:radiation effects; D017909:Levivirus / Q000254:growth & development / Q000528:radiation effects; D014466:Ultraviolet Rays; D038301:Virus Inactivation / Q000528:radiation effects; D014871:Water Microbiology; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods