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Efficacy of UVC-LED radiation in bacterial, viral, and protozoan inactivation: an assessment of the influence of exposure doses and water quality. | LitMetric

AI Article Synopsis

  • Ultraviolet light-emitting diodes (UV-LEDs) are a promising alternative to traditional mercury lamps for disinfecting water by inactivating microorganisms.
  • This study specifically examined the effectiveness of a bench-scale UVC-LED system at 280 nm on various pathogens, including E. coli, PhiX-174, MS2, and Cryptosporidium oocysts, under different water qualities.
  • Results showed that while microbiological reductions varied with exposure time and water quality, UVC-LED technology was generally effective in achieving significant reductions of bacteria and viruses, highlighting its potential for use in small water systems as recommended by the World Health Organization.

Article Abstract

Ultraviolet light-emitting diodes (UV-LEDs) have demonstrated the ability to inactivate microorganisms in water, offering an environmentally safer alternative to the conventional mercury lamp, in UV applications. While several studies have explored the microbiological effect of UVC-LEDs (200nm-280nm), limited information exists regarding their effects on waters with critical qualities. These critical qualities encompass bacteria, viruses, and protozoa - drinking water quality indicators defined by the World Health Organization for small water systems. For the first time, this work reports on the Escherichia coli, PhiX-174, MS2, and Cryptosporidium oocysts inactivation using a bench-scale UVC-LED (280 nm) water disinfection system. UV doses at a wavelength of 280 nm (UV) of up to 143.4 mJ/cm were delivered under two quality-critical water conditions: filtered water (UV transmittance at 280 nm - UVT 90.2 %) and WHO challenge water (UVT 15.7 %). Results revealed microbiological reductions dependent on exposure time and UVT. For UV dose of 16.1 mJ/cm, 2.93-3.70 log E. coli reductions were observed in UVT 90.2 % and 15.7 %, 3.49-4.21 log for PhiX-174, 0.63-0.78 log for MS2, and 0.02-0.04 log for Cryptosporidium oocysts. Significantly higher UV doses of 143.4 mJ/cm led to reductions of 3.94-5.35 log for MS2 and 0.42-0.46 log for Cryptosporidium oocysts. Statistical analysis revealed that the sensitivity among the organisms to UV exposure was E. coli = PhiX-174 > MS2 >> Cryptosporidium oocysts. Although experiments with WHO challenge water posed greater challenges for achieving 1 log reduction compared to filtered water, this difference only proved statistically significant for PhiX-174 and MS2 reductions. Overall, UVC-LED technology demonstrated notable efficacy in microbiological inactivation, achieving significant reductions based on WHO scheme of evaluation for POU technologies in both bacteria and viruses even in critical-quality waters. The findings emphasize the potential for extending the application of UVC-LED as a viable solution for household water treatment.

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Source
http://dx.doi.org/10.1016/j.watres.2024.122322DOI Listing

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