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Uv light disinfection

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...
January 29, 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 seven days...
February 2, 2018: Photochemistry and Photobiology
Sarah Willach, Holger Volker Lutze, Kevin Eckey, Katja Löppenberg, Michelle Lueling, Jens-Benjamin Wolbert, Dorothea M Kujawinski, Maik A Jochmann, Uwe Karst, Torsten Claus 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)...
January 5, 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...
December 19, 2017: 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...
December 17, 2017: 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...
December 20, 2017: Environmental Science & Technology
Ram Prakash, Afaque M Hossain, U N Pal, N Kumar, K Khairnar, M Krishna Mohan
A structurally simple dielectric barrier discharge based mercury-free plasma UV-light source has been developed for efficient water disinfection. The source comprises of a dielectric barrier discharge arrangement between two co-axial quartz tubes with an optimized gas gap. The outer electrode is an aluminium baked foil tape arranged in a helical form with optimized pitch, while the inner electrode is a hollow aluminium metallic rod, hermetically sealed. Strong bands peaking at wavelengths 172 nm and 253 nm, along with a weak band peaking at wavelength 265 nm have been simultaneously observed due to plasma radiation from the admixture of xenon and iodine gases...
December 12, 2017: Scientific Reports
Vincenzo Russotto, Andrea Cortegiani, Teresa Fasciana, Pasquale Iozzo, Santi Maurizio Raineri, Cesare Gregoretti, Anna Giammanco, Antonino Giarratano
Intensive care unit- (ICU-) acquired infections are a major health problem worldwide. Inanimate surfaces and equipment contamination may play a role in cross-transmission of pathogens and subsequent patient colonization or infection. Bacteria contaminate inanimate surfaces and equipment of the patient zone and healthcare area, generating a reservoir of potential pathogens, including multidrug resistant species. Traditional terminal cleaning methods have limitations. Indeed patients who receive a bed from prior patient carrying bacteria are exposed to an increased risk (odds ratio 2...
2017: BioMed Research International
Surapong Rattanakul, Kumiko Oguma
To demonstrate the effectiveness of UV light-emitting diodes (UV-LEDs) to disinfect water, UV-LEDs at peak emission wavelengths of 265, 280, and 300 nm were adopted to inactivate pathogenic species, including Pseudomonas aeruginosa and Legionella pneumophila, and surrogate species, including Escherichia coli, Bacillus subtilis spores, and bacteriophage Qβ in water, compared to conventional low-pressure UV lamp emitting at 254 nm. The inactivation profiles of each species showed either a linear or sigmoidal survival curve, which both fit well with the Geeraerd's model...
November 23, 2017: Water Research
Rania Nassar, Samia Mokh, Ahmad Rifai, Fatmeh Chamas, Maha Hoteit, Mohamad Al Iskandarani
Sulfaquinoxaline (SQX) is an antimicrobial of the sulfonamide class, frequently detected at low levels in drinking and surface water as organic micropollutant. The main goal of the present study is the evaluation of SQX reactivity during chlorination and UV irradiations which are two processes mainly used in water treatment plants. The SQX transformation by chlorination and UV lights (254 nm) was investigated in purified water at common conditions used for water disinfection (pH = 7.2, temperature = 25 °C, [chlorine] = 3 mg L-1)...
December 1, 2017: Environmental Science and Pollution Research International
Meiquan Cai, Peizhe Sun, Liqiu Zhang, Ching-Hua Huang
Peracetic acid (PAA) is a widely used disinfectant, and combined UV light with PAA (i.e. UV/PAA) can be a novel advanced oxidation process for elimination of water contaminants. This study is among the first to evaluate the photolysis of PAA under UV irradiation (254 nm) and degradation of pharmaceuticals by UV/PAA. PAA exhibited high quantum yields (Φ254nm = 1.20 and 2.09 mol·Einstein-1 for the neutral (PAA0) and anionic (PAA-) species, respectively) and also showed scavenging effects on hydroxyl radicals (k•OH/PAA0 = (9...
November 17, 2017: Environmental Science & Technology
Jialiang Liang, Jun Deng, Fuyang Liu, Mian Li, Meiping Tong
Bi2MoO6-AgBr hybrid photocatalyst was synthesized via a mixed solvothermal-precipitation method. The as-synthesized photocatalysts were well characterized by Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopic (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectra (DRS), as well as photoluminescence spectra (PL). The visible light driven (VLD) disinfection activity of Bi2MoO6-AgBr was tested using Escherichia coli as the model bacteria...
November 8, 2017: Colloids and Surfaces. B, Biointerfaces
John Gibson, Jennifer Drake, Bryan Karney
Municipal wastewater contains bacteria, viruses, and other pathogens that adversely affect the environment, human health, and economic activity. One way to mitigate these effects is a final disinfection step using ultraviolet light (UVL). The advantages of UVL disinfection, when compared to the more traditional chlorine, include no chlorinated by-products, no chemical residual, and relatively compact size. The design of most UV reactors is complex. It involves lamp selection, power supply design, optics, and hydraulics...
2017: Advances in Experimental Medicine and Biology
Clare Rock, Melanie S Curless, Kathryn A Carson, Elaine Nowakowski, Verna Scheeler, Lisa L Maragakis
A cluster randomized crossover trial is in progress at The Johns Hopkins Hospital to investigate the impact of daily ultraviolet (UV)-C light disinfection on the acquisition of health care-associated pathogens. To understand perceptions and challenges to daily use of UV-C, we surveyed health care workers (HCWs) and patients. Most HCWs think daily UV-C decreases the patients' risk of acquiring infection. Daily UV-C is acceptable to patients and may enhance their overall hospital experience.
October 19, 2017: American Journal of Infection Control
Lynn El Haddad, Shashank S Ghantoji, Mark Stibich, Jason B Fleming, Cindy Segal, Kathy M Ware, Roy F Chemaly
BACKGROUND: Environmental cleanliness is one of the contributing factors for surgical site infections in the operating rooms (ORs). To decrease environmental contamination, pulsed xenon ultraviolet (PX-UV), an easy and safe no-touch disinfection system, is employed in several hospital environments. The positive effect of this technology on environmental decontamination has been observed in patient rooms and ORs during the end-of-day cleaning but so far, no study explored its feasibility between surgical cases in the OR...
October 10, 2017: BMC Infectious Diseases
Jui-Hsuan Yang, Un-In Wu, Huei-Min Tai, Wang-Huei Sheng
BACKGROUND: Healthcare-associated infections caused by multidrug-resistant (MDR) pathogens are significantly associated with increased mortality and morbidity. Environmental cleaning can reduce transmission of these pathogens but is often inadequate. Adjunctive methods are warranted to enhance the effectiveness of disinfection particularly in hospital settings where healthcare-associated infections are of major concern. METHODS: We conducted a study to examine the effectiveness of a mobile, automatic device, Hyper Light Disinfection Robot (model: Hyper Light P3), which utilized ultraviolet-C (UV-C) to kill MDR-Pseudomonas aeruginosa, MDR- Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), Mycobacterium abscessus and Aspergillus fumigatus...
September 18, 2017: Journal of Microbiology, Immunology, and Infection, Wei Mian Yu Gan Ran za Zhi
Guo-Qiang Li, Wen-Long Wang, Zheng-Yang Huo, Yun Lu, Hong-Ying Hu
Studies on ultraviolet light-emitting diode (UV-LED) water disinfection have shown advantages, such as safety, flexible design, and lower starting voltages. However, information about reactivation after UV-LED disinfection is limited, which is an important issue of UV light-based technology. In this study, the photoreactivation and dark repair of Escherichia coli after UV-LEDs and low pressure (LP) UV disinfection were compared. Four UV-LED units, 265 nm, 280 nm, the combination of 265 + 280 (50%), and 265 + 280 (75%) were tested...
December 1, 2017: Water Research
Andreia Betina Kreuser Dos Santos, Elis Marina Turini Claro, Renato Nallin Montagnolli, Jaqueline Matos Cruz, Paulo Renato Matos Lopes, Ederio Dino Bidoia
Electrochemically assisted photocatalysis (by electronic drainage) is a highly promising method for disinfection of water. In this research, the efficiency of photolytic oxidation using UV-A radiation and electrochemically assisted photocatalysis (with electric potential of 1.5 V) was studied by using electrodes prepared by thermal treatment and doped with silver, for inactivation of Escherichia coli and Staphylococcus aureus. The Chick-Watson microorganism inactivation model was applied and the electrical energy consumption of the process was calculated...
December 15, 2017: Journal of Environmental Management
Oscar Janson, Erik Unosson, Maria Strømme, Håkan Engqvist, Ken Welch
OBJECTIVES: The combination of TiO2 and H2O2 under light activation constitutes a promising method for disinfection of dental prosthetics and implants, due to production of reactive oxygen species (ROS). The aim of this work was to investigate the organic degradation ability of TiO2 particles in combination with H2O2 and under light activation utilizing the organic dye rhodamine B (RhB). METHODS: Five different types of TiO2 particles, consisting of anatase, rutile, or a mixture of these crystalline phases, were combined with H2O2 and RhB, and subsequently exposed to UV (365nm) or visible (405nm) light at an irradiance of 2...
September 5, 2017: Journal of Dentistry
Rahimeh Nosrati, Ali Olad, Sahar Shakoori
In recent years more attentions have been paid for preparation of coatings with self-cleaning and antibacterial properties. These properties allow the surface to maintain clean and health over long times without any need to cleaning or disinfection. Acrylic coatings are widely used on various surfaces such as automotive, structural and furniture which their self-cleaning and antibacterial ability is very important. The aim of this work is the preparation of a polyacrylic based self-cleaning and antibacterial coating by the modification of TiO2 as a coating additive...
November 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
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