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Uv light disinfection

Hyunkyung Lee, Yongxun Jin, Seungkwan Hong
Since ultraviolet light emitting diodes (UV-LEDs) have emerged as an alternative light source for UV disinfection systems, enhancement of reactor performance is a demanding challenge to promote its practical application in water treatment process. This study explored the underlying mechanism of the inefficiency observed in flow-through mode UV disinfection tests to improve the light utilization of UV-LED applications. In particular, the disinfection performance of UV-LED reactors was evaluated using two different flow channel types, reservoir and pathway systems, in order to elucidate the impact of physical circumstances on germicidal efficiency as the light profile was adjusted...
June 7, 2018: Journal of Photochemistry and Photobiology. B, Biology
Deverick J Anderson, Rebekah W Moehring, David J Weber, Sarah S Lewis, Luke F Chen, J Conrad Schwab, Paul Becherer, Michael Blocker, Patricia F Triplett, Lauren P Knelson, Yuliya Lokhnygina, William A Rutala, Daniel J Sexton
BACKGROUND: The hospital environment is a source of pathogen transmission. The effect of enhanced disinfection strategies on the hospital-wide incidence of infection has not been investigated in a multicentre, randomised controlled trial. We aimed to assess the effectiveness of four disinfection strategies on hospital-wide incidence of multidrug-resistant organisms and Clostridium difficile in the Benefits of Enhanced Terminal Room (BETR) Disinfection study. METHODS: We did a prespecified secondary analysis of the results from the BETR Disinfection study, a pragmatic, multicentre, crossover cluster-randomised trial that assessed four different strategies for terminal room disinfection in nine hospitals in the southeastern USA...
June 4, 2018: Lancet Infectious Diseases
Yang Qiao, Daoyi Chen, Diya Wen
The development of subsea injection water disinfection systems will enable the novel exploration of offshore oilfields. Ultraviolet light emitting diodes (UV-LEDs) with peak wavelengths at 255 nm, 280 nm, 350 nm, and combinations of 255 nm and 350 nm, and 280 nm and 350 nm were investigated in this study to determine their efficiency at disinfecting saprophytic bacteria, iron bacteria, and sulfate reducing bacteria. Results show that UV-LEDs with peak wavelengths at 280 nm were the most practical in this domain because of their high performance in both energy-efficiency and reactivation suppression, although 255 nm UV-LEDs achieved an optimal germicidal effect in dose-based experiments...
June 4, 2018: Science of the Total Environment
Lin Deng, Longjia Wen, Wenjuan Dai, Rajendra Prasad Singh
Low-pressure (LP) UV treatment after chlorine disinfection was associated with enhanced formation of trichloronitromethane (TCNM), a halonitromethane disinfection by-product (DBP), due to the chlorination of tryptophan. Evidence was found that the concentration of TCNM from tryptophan increased quickly to the maximum for the first instance. Moreover, the increase of TCNM under UV exceeded 10 times than under dark. Then, it was found to have an obvious decrease in the formation of TCNM, even finally hardly disappear...
June 4, 2018: Environmental Science and Pollution Research International
Y Xiao, X N Chu, M He, X C Liu, J Y Hu
Ultraviolet (UV) light emission diode (LED), which is mercury free and theoretically more energy efficient, has now become an alternative to conventional UV lamps in water disinfection industry. In this research, the disinfection performance of a novel sequential process, UVA365nm LED followed by UVC265nm LED (UVA-UVC), was evaluated. The results revealed that the responses of different bacterial strains to UVA-UVC varied. Coupled with appropriate dosages of UVC, a 20 min UVA pre-radiation provided higher inactivations (log inactivation) of E...
May 15, 2018: Water Research
Miloch Marjanovic, Stefanos Giannakis, Dominique Grandjean, Luiz Felippe de Alencastro, Cesar Pulgarin
In this work, solar disinfection (SODIS) was enhanced by moderate addition of Fe and sodium peroxydisulfate (PDS), under solar light. A systematic assessment of the activating factors was performed, firstly isolated, then in pairs and concluded in the combined Fe/heat/solar UV-PDS activation process. Solar light was the most effective (single) activator, and its combination with Fe and heat (double activation) yielded high level of synergies (up to S = 2.13). The triple activation was able to reduce the bacterial load up to 6-log in less than 1 h, similarly to the photo-Fenton process done in comparison (SODIS alone: >5 h)...
April 26, 2018: Water Research
M Sisti, G F Schiavano, M DE Santi, G Brandi
We investigated the effect of ultraviolet germicidal irradiation (UVI) from a low-pressure mercury lamp on several pathogenic Aspergillus spp. including A. flavipes, A. flavus, A. fumigatus, A. glaucus, A. nidulans, A. niger, A. terreus, A. ustus and A. versicolor suspended in tap water under laboratory-scale conditions. It was shown that within 10 s of exposure, time species such as A. glaucus, A. niudulans and A. ustus were completely inactivated, while 40 s were needed for the elimination of all the species tested...
December 2017: Journal of Preventive Medicine and Hygiene
Sarah Simmons, Charles Dale, James Holt, Deborah G Passey, Mark Stibich
BACKGROUND: Manual cleaning and disinfection of the operating room (OR) environment may be inadequate due to human error. No-touch technologies, such as pulsed-xenon ultraviolet light (PX-UV), can be used as an adjunct to manual cleaning processes to reduce surface contamination in the OR. This article reports the cumulative results from 23 hospitals across the United States that performed microbiologic validation of PX-UV disinfection after manual cleaning. METHODS: We obtained samples from 732 high-touch surfaces in 136 ORs at 23 hospitals, after manual terminal cleaning, and again after PX-UV disinfection (n = 1464 surface samples)...
April 13, 2018: American Journal of Infection Control
B A Omran, H N Nassar, N A Fatthallah, A Hamdy, E H El-Shatoury, N Sh El-Gendy
AIMS: Since mycosynthesis of metal nanoparticles (NPs) is advertised as a promising and ecofriendly approach. Thus, this study aims to investigate the capability of Aspergillus brasiliensis ATCC 16404 for mycosynthesis of silver NPs (AgNPs). METHODS AND RESULTS: One-factor-at-a-time-technique was used to study the effect of different physicochemical parameters: the reaction time, pH, temperature, different stirring rates, illumination, and finally, the different concentrations of silver nitrate and fungal biomass on the mycosynthesis of AgNPs...
April 6, 2018: Journal of Applied Microbiology
Wanzhong Zhang, Haiyu Huang, Zhiming Sun, Shuilin Zheng, Caihong Yu
The aim of this work was to prepare, characterize and evaluate the potential of novel ZnO/stellerite composite photocatalysts against Staphylococcus aureus (S. aureus). SEM/EDS studies employed to study the surface morphological properties revealed stellerite as the catalysts carrier played a role of dispersant for ZnO nanoparticles. The XRD patterns of the ZnO/stellerite indicated hexagonal crystal structure with 20-30 nm size. It was found that the crystallite size of ZnO/stellerite was much smaller as compared to pure ZnO and increased with increasing ZnO loading amount...
May 2018: Journal of Photochemistry and Photobiology. B, Biology
Diego Averaldo Guiguet Leal, Doris Sobral Marques Souza, Karin Silva Caumo, Gislaine Fongaro, Lua Ferreira Panatieri, Maurício Durigan, Marilise Brittes Rott, Célia Regina Monte Barardi, Regina Maura Bueno Franco
Waterborne, food-borne and sewage-borne pathogens are a major global concern, with the annual recurrence, most notably during the summer, of outbreaks of gastroenteritis of unconfirmed etiology associated with recreational activities in marine environments. The consumption of contaminated water-based foodstuffs is also related to outbreaks of human illness. The main goals of the present study were: i) to identify the genetic assemblages of Giardia duodenalis cysts in growing and depurated oysters destined for human consumption on the southern coast of São Paulo, Brazil; ii) to verify the main circulating G...
June 15, 2018: Water Research
Yi Wang, Yang Long, Zhiqing Yang, Dun Zhang
Visible-light-driven (VLD) BiOI/BiOBr heterostructure films with hierarchical microstructure have been firstly fabricated on 304 stainless steel wire mesh (304SSWM) substrates through a novel ion-exchange method using the BiOI film as precursor. The concentration of tetrabutylammonium bromide (TBAB) is the key factor to control the composition and microstructure of BiOI/BiOBr films. Physical, chemical, and optical properties of BiOI/BiOBr heterostructure films were characterized by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy, high resolution transmittance electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance absorption, and fluorescence spectrophotometer, respectively...
June 5, 2018: Journal of Hazardous Materials
(no author information available yet)
Background: Hospital-acquired infections (HAIs) are infections that patients contract while in the hospital that were neither present nor developing at the time of admission. In Canada an estimated 10% of adults with short-term hospitalization have HAIs. According to 2003 Canadian data, between 4% and 6% of these patients die from these infections. The most common HAIs in Ontario are caused by Clostridium difficile . The standard method of reducing and preventing these infections is decontamination of patient rooms through manual cleaning and disinfection...
2018: Ontario Health Technology Assessment Series
David Polo, Irene García-Fernández, Pilar Fernández-Ibañez, Jesús L Romalde
This study evaluates and compares the effectiveness of solar photo-Fenton systems for the inactivation of hepatitis A virus (HAV) in water. The effect of solar irradiance, dark- Fenton reaction and three different reactant concentrations (2.5/5, 5/10 and 10/20 mg/L of Fe2+ /H2 O2 ) on the photo-Fenton process were tested in glass bottle reactors (200 mL) during 6 h under natural sunlight. Disinfection kinetics were determined both by RT-qPCR and infectivity assays. Mean water temperatures ranged from 25 to 27...
February 21, 2018: Food and Environmental Virology
Charles P Gerba, Walter Q Betancourt, Masaaki Kitajima, Channah M Rock
Treatment of wastewater for potable reuse requires the reduction of enteric viruses to levels that pose no significant risk to human health. Advanced water treatment trains (e.g., chemical clarification, reverse osmosis, ultrafiltration, advanced oxidation) have been developed to provide reductions of viruses to differing levels of regulatory control depending upon the levels of human exposure and associated health risks. Importance in any assessment is information on the concentration and types of viruses in the untreated wastewater, as well as the degree of removal by each treatment process...
April 15, 2018: Water Research
Kumiko Oguma, Kaori Kanazawa, Ikuro Kasuga, Satoshi Takizawa
Ultraviolet light emitting diodes (UV-LEDs) are small mercury-free devices that can be installed at the point of use (POU) of water for disinfection. Considering that heterotrophic bacteria are of concern in drinking water systems, we applied a flow-through UV-LED apparatus to dechlorinated tap water, and determined the heterotrophic plate count (HPC) in samples after UV-LED exposure (UV+) compared to samples without UV-LED application (UV-). The UV+ and UV- samples were maintained at 20°C to track HPC profiles during storage for 7 days...
February 2, 2018: Photochemistry and Photobiology
Sarah Willach, Holger V Lutze, Kevin Eckey, Katja Löppenberg, Michelle Lüling, Jens-Benjamin Wolbert, Dorothea M Kujawinski, Maik A Jochmann, Uwe Karst, Torsten C Schmidt
The environmental micropollutant sulfamethoxazole (SMX) is susceptible to phototransformation by sunlight and UV-C light which is used for water disinfection. Depending on the environmental pH conditions SMX may be present as neutral or anionic species. This study systematically investigates the phototransformation of these two relevant SMX species using four different irradiation scenarios, i.e., a low, medium, and high pressure Hg lamp and simulated sunlight. The observed phototransformation kinetics are complemented by data from compound-specific stable isotope and transformation product analysis using isotope-ratio and high-resolution mass spectrometry (HRMS)...
February 6, 2018: Environmental Science & Technology
Lei Zhang, Cheng-Gang Niu, Xiao-Ju Wen, Hai Guo, Xiu-Fei Zhao, Da-Wei Huang, Guang-Ming Zeng
Exploring morphology and surface structure of semiconductor photocatalyst is crucial for researching their photocatalytic performance. In this paper, hollow CdS nanospheres (CdS-HSs) were successfully fabricated via simple template self-removal strategy. The prepared CdS-HSs were characterized by XRD, SEM, HR-TEM, UV-vis diffuse reflectance spectra (DRS), XPS, photocurrent response (I-T), photoluminescence (PL) and electrochemistry impedance spectroscopy (EIS). It was found that the prepared CdS-HSs have nanoparticles-textured surface composed of ultra-small CdS nanoparticles (∼20 nm) and large surface areas...
March 15, 2018: Journal of Colloid and Interface Science
Sudheera Yaparatne, Carl P Tripp, Aria Amirbahman
Disinfection by ultraviolet (UV) radiation is a growing trend in public water treatment systems because of its effectiveness with respect to inactivation of protozoa and other pathogenic microorganisms. However, removal of different classes of organic compounds, including taste and odor compounds in water is not effective with UV irradiation. In this study, a novel TiO2 -based immobilized photocatalyst is developed to enhance the UV photodegradation of two of the major taste and odor compounds, 2-methylisoborneol (MIB) and Geosmin (GSM) in water...
March 15, 2018: Journal of Hazardous Materials
Sara E Beck, Natalie M Hull, Christopher Poepping, Karl G Linden
Adenovirus, a waterborne pathogen responsible for causing bronchitis, pneumonia, and gastrointestinal infections, is highly resistant to UV disinfection and therefore drives the virus disinfection regulations set by the U.S. Environmental Protection Agency. Polychromatic UV irradiation has been shown to be more effective at inactivating adenovirus and other viruses than traditional monochromatic irradiation emitted at 254 nm; the enhanced efficacy has been attributed to UV-induced damage to viral proteins. This research shows UV-induced damage to adenoviral proteins across the germicidal UV spectrum at wavelength intervals between 200 and 300 nm...
January 2, 2018: Environmental Science & Technology
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