title: A new dual-collimation batch reactor for determination of ultraviolet inactivation rate constants for microorganisms in aqueous suspensions.
abstract: We developed, characterized, and tested a new dual-collimation aqueous UV reactor to improve the accuracy and consistency of aqueous k-value determinations. This new system is unique because it collimates UV energy from a single lamp in two opposite directions. The design provides two distinct advantages over traditional single-collimation systems: 1) real-time UV dose (fluence) determination; and 2) simple actinometric determination of a reactor factor that relates measured irradiance levels to actual irradiance levels experienced by the microbial suspension. This reactor factor replaces three of the four typical correction factors required for single-collimation reactors. Using this dual-collimation reactor, Bacillus subtilis spores demonstrated inactivation following the classic multi-hit model with k=0.1471cm(2)/mJ (with 95% confidence bounds of 0.1426 to 0.1516).
authors: Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Respiratory Health Division, Field Studies Branch, 1095 Willowdale Road, Morgantown, WV 26505, USA; Pennsylvania State University, College of Engineering, Department of Architectural Engineering, Indoor Environment Center, 104 Engineering Unit A, University Park, PA 16802, USA. Electronic address: SMartin1@cdc.gov.
authors: Stephen B
authors: SB
authors: Martin
authors: Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Respiratory Health Division, Field Studies Branch, 1095 Willowdale Road, Morgantown, WV 26505, USA.
authors: Elizabeth S
authors: ES
authors: Schauer
authors: Massachusetts Institute of Technology, Department of Architecture, Building Technology Laboratory, 77 Massachusetts Avenue, Room 5-418, Cambridge, MA 02139, USA.
authors: David H
authors: DH
authors: Blum
authors: Pennsylvania State University, College of Engineering, Department of Architectural Engineering, Indoor Environment Center, 104 Engineering Unit A, University Park, PA 16802, USA.
authors: Paul A
authors: PA
authors: Kremer
authors: Pennsylvania State University, College of Engineering, Department of Architectural Engineering, Indoor Environment Center, 104 Engineering Unit A, University Park, PA 16802, USA.
authors: William P
authors: WP
authors: Bahnfleth
authors: Pennsylvania State University, College of Engineering, Department of Architectural Engineering, Indoor Environment Center, 104 Engineering Unit A, University Park, PA 16802, USA.
authors: James D
authors: JD
authors: Freihaut
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D013171:Spores, Bacterial / Q000528:radiation effects*; D014466:Ultraviolet Rays; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
keywords: Bacillus subtilis; Collimated-beam reactor; Germicidal; Inactivation rate constant; Ultraviolet; k-Value