Abstract
Treatment with ultraviolet (UV) light is a common option for inactivating waterborne organisms. The mercury vapor lamps conventionally used as a source of UV-C light for water disinfection are eventually replaced by light emitter diodes (LEDs) in the middle term due to their higher efficiency and lack of hazardous materials. Nonetheless, biological mechanisms for repairing UV damage caused by the UV treatment are some of its significant undesirable features. The objective of this study is to evaluate and compare the UV-resistance and the reactivation degree in different strains of E. coli and E. faecalis treated with a flow-through reactor equipped with LEDs with an emission range between 265 and 285 nm. The treated organisms were subjected to various illumination regimes after the UV irradiation. The results obtained indicated that intraspecific differences between the strains of E. coli were greater than the interspecific differences with respect to E. faecalis in terms of UV-resistance and repairing potential. The UV doses necessary to achieve four log-reductions ranged from 10.2 to 16.3 mJ cm−2 for E. coli and from 11.1 to 11.4 for mJ cm−2 for E. faecalis. Dark repair was not observed within 24 h after the UV irradiation whereas the degree of photorepair depended on both the bacteria strain and the applied UV dose. The exposure of the irradiated organisms to an illuminated environment entailed and increasing between the 18 % and the 160 % of the UV dose required to achieve four log-reductions.
Original language | English |
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Article number | 103497 |
Journal | Journal of Water Process Engineering |
Volume | 52 |
DOIs | |
State | Published - Apr 2023 |
Bibliographical note
Funding Information:This work has been co-funded by the 2014–2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia (Spain). Projects Ref.: FEDER-UCA18-108023 and FEDER-UCA18-105151. J. Moreno-Andrés acknowledges Grant IJC2020–042741-I funded by MCIN / AEI / 10.13039/501100011033 and by the European Union NextGenerationEU/PRTR.
Publisher Copyright:
© 2023 The Author(s)
Keywords
- Fecal bacteria
- Light emitting diodes (LEDs)
- Photoreactivation
- Ultraviolet inactivation
- Water disinfection