New water disinfection system using UVA light-emitting diodes
Article first published online: 30 AUG 2007
Journal of Applied Microbiology
Volume 103, Issue 6, pages 2291–2298, December 2007
How to Cite
Hamamoto, A., Mori, M., Takahashi, A., Nakano, M., Wakikawa, N., Akutagawa, M., Ikehara, T., Nakaya, Y. and Kinouchi, Y. (2007), New water disinfection system using UVA light-emitting diodes. Journal of Applied Microbiology, 103: 2291–2298. doi: 10.1111/j.1365-2672.2007.03464.x
- Issue published online: 30 AUG 2007
- Article first published online: 30 AUG 2007
- 2007/0239: received 15 February 2007, revised 26 April 2007 and accepted 8 May 2007
- DNA damage;
- light-emitting diode;
- ultraviolet irradiation
Aim: To evaluate the ability of high-energy ultraviolet A (UVA) light-emitting diode (LED) to inactivate bacteria in water and investigate the inactivating mechanism of UVA irradiation.
Methods and Results: We developed a new disinfection device equipped with high-energy UVA-LED. Inactivation of bacteria was determined by colony-forming assay. Vibrio parahaemolyticus, enteropathogenic Escherichia coli, Staphylococcus aureus and Escherichia coli DH5α were reduced by greater than 5-log10 stages within 75 min at 315 J cm−2 of UVA. Salmonella enteritidis was reduced greater than 4-log10 stages within 160 min at 672 J cm−2 of UVA. The formation of 8-hydroxy-2′-deoxyguanosine in UVA-LED irradiated bacteria was 2·6-fold higher than that of UVC-irradiated bacteria at the same inactivation level. Addition of mannitol, a scavenger of hydroxyl radicals (OH˙), or catalase, an enzyme scavenging hydrogen peroxide (H2O2) to bacterial suspensions significantly suppressed disinfection effect of UVA-LED.
Conclusion: This disinfection system has enough ability to inactivate bacteria and OH˙ and H2O2 participates in the disinfection mechanism of UVA irradiation.
Significance and Impact of the Study: We newly developed UVA irradiation system and found that UVA alone was able to disinfect the water efficiently. This will become a useful disinfection system.