Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Avenida Trabalhador São-Carlense 400, São Carlos, São Paulo, 13566-590, Brazil.
São Carlos Institute of Physics, University of São Paulo, Avenida Trabalhador São-Carlense 400, São Carlos, São Paulo, 13566-590, Brazil.
Water Res. 2024 Nov 15;266:122322. doi: 10.1016/j.watres.2024.122322. Epub 2024 Aug 24.
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.
紫外线发光二极管 (UV-LED) 已证明能够在水中灭活微生物，为紫外线应用中的传统汞灯提供了一种更安全的环境替代方案。虽然已有多项研究探讨了 UVC-LED（200nm-280nm）的微生物效应，但对于具有关键水质的水，其影响的相关信息有限。这些关键水质涵盖了细菌、病毒和原生动物，它们是世界卫生组织为小型水系统定义的饮用水质量指标。首次使用台式紫外线 LED（280nm）水消毒系统，报告了大肠杆菌、phiX-174、MS2 和隐孢子虫卵囊的灭活情况。在两种关键水质条件下：过滤水（280nm 紫外线透射率-UVT90.2%）和世卫组织挑战水（UVT15.7%），传递了波长为 280nm（UV）的高达 143.4mJ/cm 的紫外线剂量。结果表明，微生物减少量取决于暴露时间和 UVT。对于 16.1mJ/cm 的紫外线剂量，在 UVT90.2%和 15.7%下观察到大肠杆菌减少 2.93-3.70log，phiX-174 减少 3.49-4.21log，MS2 减少 0.63-0.78log，隐孢子虫卵囊减少 0.02-0.04log。显著更高的 143.4mJ/cm 紫外线剂量导致 MS2 减少 3.94-5.35log，隐孢子虫卵囊减少 0.42-0.46log。统计分析表明，这些生物体对紫外线暴露的敏感性为大肠杆菌=phiX-174>MS2>>隐孢子虫卵囊。虽然与过滤水相比，使用世卫组织挑战水进行实验对实现 1 个对数减少提出了更大的挑战，但这种差异仅在 phiX-174 和 MS2 减少方面具有统计学意义。总体而言，UVC-LED 技术在微生物灭活方面表现出显著的功效，根据世卫组织方案对 POUT 技术在细菌和病毒方面的评估，即使在关键水质条件下，也实现了显著减少。这些发现强调了将 UVC-LED 作为家庭水处理可行解决方案的应用潜力。
