Abstract
To introduce UV-LED to Point-of-Use (POU) water treatment devices at a tap, the risk of microbial photoreactivation is of concern because microorganisms are exposed to visible light immediately after UV disinfection. In this study, UV-LEDs with peak emission at 265 nm, 280 nm and 300 nm were used to inactivate Escherichia coli (E. coli) and subsequent photoreactivation was investigated. The results revealed that inactivation by 265 nm or 280 nm UV-LEDs was efficient equivalently, while 300 nm UV-LED showed lower inactivation efficiency, and comparison of the electrical energy for 3log reduction showed that 280 nm UV-LED was most efficient to inactivate E. coli under the conditions adopted in this study. Meanwhile, regardless of inactivation wavelengths, photoreactivation occurred after 3log reduction and the log inactivation after photoreactivation were 0.51, 0.55 and 0.42log for 265 nm, 280 nm and 300 nm UV-LEDs, respectively. The results of this study indicated fundamental information to apply UV-LED to POU devices.
