in-use comparison of in-line and in-tank ultraviolet devices for reduction of the microbial load in water coolers

• Published in: Journal of foodservice Vol. 18; no. 3; pp. 101 - 107
• Main Authors: Hall, A, Fielding, L.M, Peters, A.C
• Format: Journal Article
• Language: English
• Published: Malden, USA : Blackwell Publishing Inc 01.06.2007
• Subjects: chilled water tank; coolers; Escherichia coli; food processing equipment; food service; microbial load; tanks; tap water; ultraviolet radiation; water dis; water pollution; water supply; water treatment
• ISSN: 1748-0140; 1748-0159
• DOI: 10.1111/j.1745-4506.2007.00053.x

Two ultraviolet (UV) systems were evaluated for use in water-cooling devices: in-tank (8 W, held in the centre of a 2-L chilled water tank) and in-line (6 W, treating chilled water at the point of dispense). The efficacy of these devices, under conditions of continual dispense (2 L/min), against a range of bacteria commonly associated with drinking water, was investigated. A rate of 1 L/min and the impact of a periodic dispense pattern (machine was not dispensing for 1 min between sampling) was examined with Escherichia coli. At 2 L/min, both devices achieved a 3 log reduction. At 1 L/min, both devices achieved greater than 4 log reduction. During periodic dispense, the in-line device achieved a 3 log reduction, while the in-tank device achieved greater than a 4 log reduction. UV was effective at reducing levels of bacteria commonly associated with water to acceptable levels. Under conditions of periodic use, the in-tank device showed greater potential.