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Oguma K. Field demonstration of UV-LED disinfection at small and decentralized water facilities. JOURNAL OF WATER AND HEALTH 2023; 21:1369-1384. [PMID: 37756202 PMCID: wh_2023_192 DOI: 10.2166/wh.2023.192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Ultraviolet light-emitting diodes (UV-LED) can be a good option for disinfecting water in small and decentralized facilities. A flow-through UV-LED disinfection module was evaluated at three remote locations in Japan. The disinfection efficiency of the module was monitored for over one year, targeting indigenous Escherichia coli, total coliforms, standard plate count, and heterotrophic plate count (HPC) bacteria. The physicochemical parameters of the source water, including UV transmittance (UVT), were also monitored to understand their natural fluctuation and impacts on UV disinfection. Overall, the UV-LED module showed efficient disinfection at all locations, achieving 2.7 log inactivation of E. coli at 30 L/min in a community-based water supply. HPC inactivation did not significantly differ among the three test sites (p > 0.01). One test site experienced a decrease in HPC inactivation after 10 months, whereas the other two sites did not show performance deterioration after one year. HPC inactivation was not correlated with the UVT of source water at any location, implying the difficulty to use UVT as a single parameter to predict disinfection efficiency in practical applications. This study demonstrates the effectiveness of UV-LED technology for water disinfection in small and decentralized water supply systems.
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Affiliation(s)
- Kumiko Oguma
- Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo. 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan E-mail:
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2
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Demeersseman N, Saegeman V, Cossey V, Devriese H, Schuermans A. Shedding a light on ultraviolet-C technologies in the hospital environment. J Hosp Infect 2023; 132:85-92. [PMID: 36565930 PMCID: PMC9769028 DOI: 10.1016/j.jhin.2022.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022]
Abstract
Ultraviolet (UV)-C light for disinfection has experienced a surge in popularity since the outbreak of COVID-19. Currently, many different UV-C systems, with varied properties that impact disinfection performance, are available on the market. Therefore this review aims to bundle the available information on UV-C disinfection to obtain an overview of its advantages, disadvantages, and performance-influencing parameters. A literature search was performed using the snowball search method in Google Scholar and PubMed with the following keywords: UV-C disinfection, UV-C dose, UV-C light source, UV-C repair mechanism, UV-C photoreactivation, and UV-C disinfection standards. The main parameters of UV-C disinfection are wavelength, dose, relative humidity, and temperature. There is no consensus about their optimal values, but, in general, light at a high dose and a spectrum of wavelengths containing 260 nm is preferred in an environment at room temperature with low relative humidity. This light can be generated by mercury-vapour, light-emitting diode (LED), pulsed-xenon, or excimer lamps. Multiple factors are detrimental to disinfection performance such as shadowing, a rough surface topography, a high level of contamination, repair mechanisms, and the lack of standardization. Also, there are health and safety risks associated with the UV-C technology when used in the proximity of people. UV-C disinfection systems have promising features and the potential to improve in the future. However, clarifications surrounding the different parameters influencing the technologies' effectiveness in hospital environment are needed. Therefore UV-C disinfection should currently be considered for low-level rather than high-level disinfection.
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Affiliation(s)
- N Demeersseman
- Department of Infection Control and Prevention, University Hospitals Leuven and Catholic University Leuven, Leuven, Belgium
| | - V Saegeman
- Department of Infection Control and Prevention, University Hospitals Leuven and Catholic University Leuven, Leuven, Belgium
| | - V Cossey
- Department of Infection Control and Prevention, University Hospitals Leuven and Catholic University Leuven, Leuven, Belgium
| | - H Devriese
- Department of Prevention and Environment, University Hospitals Leuven and Catholic University Leuven, Leuven, Belgium
| | - A Schuermans
- Department of Infection Control and Prevention, University Hospitals Leuven and Catholic University Leuven, Leuven, Belgium.
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Chen PY, Chu XN, Liu L, Hu JY. Effect of salinity on medium- and low-pressure UV disinfection of Vibrio cholerae. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2018; 77:655-661. [PMID: 29431710 DOI: 10.2166/wst.2017.520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The problem of biological invasions attributed to ballast water release is an ongoing problem that threatens ecosystems and human health. Ultraviolet (UV) radiation has been increasingly used for ballast water treatment mainly due to the advantages of short contact time and minimized harmful disinfection by products. In this study, the impact of salinity on the inactivation of Vibrio cholerae (NCTC 7253) was examined, and comparison of inactivation level and disinfection kinetics after medium-pressure (MP) (1 kW) and low-pressure (LP) (10 W) UV irradiation was made. MP UV exposure resulted in higher inactivation efficacy against V. cholerae than LP UV exposure especially at lower UV doses (≤3 mJ cm-2) and salinity had a negative impact on both MP and LP UV disinfection, especially at higher UV doses (≥3 mJ cm-2 for MP and ≥4 mJ cm-2 for LP). To understand the mechanisms of salinity effect on V. cholerae, the enzyme-linked immunosorbent assay (ELISA) was employed to determine the number of cyclobutane pyrimidine dimers (CPDs), one major type of DNA damage. No significant effects of salinity were found at the CPDs level except for 3% artificial seawater after LP UV exposure case. It is imperative that site-specific conditions of salinity be taken into account in the design of UV reactors to treat V. cholerae and other species.
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Affiliation(s)
- P Y Chen
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore E-mail:
| | - X N Chu
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore E-mail:
| | - L Liu
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore E-mail:
| | - J Y Hu
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore E-mail:
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Li Y, Yang M, Zhang X, Jiang J, Liu J, Yau CF, Graham NJD, Li X. Two-step chlorination: A new approach to disinfection of a primary sewage effluent. WATER RESEARCH 2017; 108:339-347. [PMID: 27839829 DOI: 10.1016/j.watres.2016.11.019] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/02/2016] [Accepted: 11/03/2016] [Indexed: 05/15/2023]
Abstract
Sewage disinfection aims at inactivating pathogenic microorganisms and preventing the transmission of waterborne diseases. Chlorination is extensively applied for disinfecting sewage effluents. The objective of achieving a disinfection goal and reducing disinfectant consumption and operational costs remains a challenge in sewage treatment. In this study, we have demonstrated that, for the same chlorine dosage, a two-step addition of chlorine (two-step chlorination) was significantly more efficient in disinfecting a primary sewage effluent than a one-step addition of chlorine (one-step chlorination), and shown how the two-step chlorination was optimized with respect to time interval and dosage ratio. Two-step chlorination of the sewage effluent attained its highest disinfection efficiency at a time interval of 19 s and a dosage ratio of 5:1. Compared to one-step chlorination, two-step chlorination enhanced the disinfection efficiency by up to 0.81- or even 1.02-log for two different chlorine doses and contact times. An empirical relationship involving disinfection efficiency, time interval and dosage ratio was obtained by best fitting. Mechanisms (including a higher overall Ct value, an intensive synergistic effect, and a shorter recovery time) were proposed for the higher disinfection efficiency of two-step chlorination in the sewage effluent disinfection. Annual chlorine consumption costs in one-step and two-step chlorination of the primary sewage effluent were estimated. Compared to one-step chlorination, two-step chlorination reduced the cost by up to 16.7%.
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Affiliation(s)
- Yu Li
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Mengting Yang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China; College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, Hong Kong, China.
| | - Xiangru Zhang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
| | - Jingyi Jiang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Jiaqi Liu
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Cie Fu Yau
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Nigel J D Graham
- Department of Civil and Environmental Engineering, Imperial College London, London, UK
| | - Xiaoyan Li
- Department of Civil Engineering, The University of Hong Kong, Hong Kong, China
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Chen PY, Chu XN, Liu L, Hu JY. Effects of salinity and temperature on inactivation and repair potential of Enterococcus faecalis
following medium- and low-pressure ultraviolet irradiation. J Appl Microbiol 2016; 120:816-25. [DOI: 10.1111/jam.13026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/19/2015] [Accepted: 10/30/2015] [Indexed: 11/29/2022]
Affiliation(s)
- P.-Y. Chen
- Department of Civil and Environmental Engineering; National University of Singapore; Singapore Singapore
| | - X.-N. Chu
- Department of Civil and Environmental Engineering; National University of Singapore; Singapore Singapore
| | - L. Liu
- Department of Civil and Environmental Engineering; National University of Singapore; Singapore Singapore
| | - J.-Y. Hu
- Department of Civil and Environmental Engineering; National University of Singapore; Singapore Singapore
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Guo M, Huang J, Hu H, Liu W, Yang J. UV inactivation and characteristics after photoreactivation of Escherichia coli with plasmid: health safety concern about UV disinfection. WATER RESEARCH 2012; 46:4031-4036. [PMID: 22683407 DOI: 10.1016/j.watres.2012.05.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 04/25/2012] [Accepted: 05/03/2012] [Indexed: 06/01/2023]
Abstract
Occurrence and degree of photoreactivation after ultraviolet (UV) exposure have been widely studied. However, the characteristics of photoreactivated microorganisms were rarely investigated. Hence, in this study, Escherichia coli with plasmids of ampicillin (amp)-resistance or fluorescence was used as indicators to examine the UV inactivation efficiencies and variations of characteristics of E. coli after subsequent photoreactivation. The experimental results indicate that the amp-resistant bacteria and the fluorescent bacteria used in this study had similar trends of UV dose-response curves. 3.5-log(10) and 3-log(10) reductions were achieved with a UV dose of 5 mJ/cm(2) for the amp-resistant and fluorescent E. coli, respectively. There was no significant difference in the UV inactivation behavior, as compared with common strains of E. coli. For the amp-resistant E. coli and the fluorescent E. coli, after exposures with UV doses of 5, 15, 25, 40 and 80 mJ/cm(2), the corresponding percent photoreactivations after a 4 h exposure to photoreactivating light were 1% and 46% respectively for a UV dose of 5 mJ/cm(2), and essentially negligible for all other UV doses. Furthermore, the photoreactivated amp-resistant bacteria still have the ability of amp-resistance. And the revived fluorescent E. coli showed similar fluorescent behavior, compared with the untreated bacteria. The experimental results imply that after UV inactivation and subsequent photoreactivation, the bacteria retained the initial characteristics coded in the plasmid. This reveals a possibility that some characteristics of bacteria can retain or recover through photoreactivation, and a safety concern about pathogenicity revival might need to be considered with UV disinfection and photoreactivation.
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Affiliation(s)
- Meiting Guo
- College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
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Wang X, Hu X, Hu C, Wei D. Sequential use of ultraviolet light and chlorine for reclaimed water disinfection. J Environ Sci (China) 2011; 23:1605-1610. [PMID: 22432254 DOI: 10.1016/s1001-0742(10)60630-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Several disinfection processes of ultraviolet (UV), chlorine or UV followed by chlorine were investigated in municipal wastewater according to the inactivation of Escherichia coli, Shigella dysenteriae and toxicity formation. The UV inactivation of the tested pathogenic bacteria was not affected by the quality of water. It was found that the inactivated bacteria were obviously reactivated after one day in dark. Fluorescent light irradiation increased the bacteria repair. The increase of UV dosage could cause more damage to bacteria to inhibit bacteria self-repair. No photoreactivation was detected when the UV dose was up to 80 mJ/cm2 for E. coli DH5alpha, and 23 mJ/cm2 for S. dysenteriae. Nevertheless, sequential use of 8 mJ/cm2 of UV and low concentration of chlorine (1.5 mg/L) could effectively inhibit the photoreactivation and inactivate E. coli below the detection limits within seven days. Compared to chlorination alone, the sequential disinfection decreased the genotoxicity of treated wastewater, especially for the sample with high NH3-N concentration.
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Affiliation(s)
- Xiujuan Wang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Quek P, Hu J. Influence of photoreactivating light intensity and incubation temperature on photoreactivation ofEscherichia colifollowing LP and MP UV disinfection. J Appl Microbiol 2008; 105:124-33. [DOI: 10.1111/j.1365-2672.2008.03723.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Indicators for photoreactivation and dark repair studies following ultraviolet disinfection. J Ind Microbiol Biotechnol 2008; 35:533-41. [DOI: 10.1007/s10295-008-0314-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 01/08/2008] [Indexed: 11/26/2022]
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