scholarly journals Effects of UV Radiation on Photolyase and Implications with Regards to Photoreactivation following Low- and Medium-Pressure UV Disinfection

2007 ◽  
Vol 74 (1) ◽  
pp. 327-328 ◽  
Author(s):  
Jiangyong Hu ◽  
Puay Hoon Quek
Keyword(s):  
Uv Radiation ◽  
Uv Irradiation ◽  
Flavin Adenine Dinucleotide ◽  
Low Pressure ◽  
Uv Disinfection ◽  
Medium Pressure ◽  
Uv Lamps

ABSTRACT Photolyase activity following exposure to low-pressure (LP) and medium-pressure (MP) UV lamps was evaluated. MP UV irradiation resulted in a greater reduction in photolyase activity than LP UV radiation. The results suggest that oxidation of the flavin adenine dinucleotide in photolyase may have caused the decrease in activity.

scholarly journals Molecular Indications of Protein Damage in Adenoviruses after UV Disinfection

2010 ◽  
Vol 77 (3) ◽  
pp. 1145-1147 ◽  
Author(s):  
Anne C. Eischeid ◽  
Karl G. Linden
Keyword(s):  
Cell Culture ◽  
Viral Proteins ◽  
Low Pressure ◽  
Protein Damage ◽  
Uv Disinfection ◽  
Medium Pressure ◽  
The Difference ◽  
Uv Lamp ◽  
Detailed Work

ABSTRACTAdenoviruses are resistant to monochromatic, low-pressure (LP) UV disinfection—but have been shown to be susceptible to inactivation by polychromatic, medium-pressure (MP) UV—when assayed using cell culture infectivity. One possible explanation for the difference between UV lamp types is that the additional UV wavelengths emitted by MP UV enable it to cause greater damage to viral proteins than LP UV. The objective of this study was to examine protein damage in adenoviruses treated with LP and MP UV. Results show that MP UV is more effective at damaging viral proteins at high UV doses, though LP UV caused some damage as well. To our knowledge, this study is the first to investigate protein damage in UV-treated adenovirus, and the overview presented here is expected to provide a basis for further, more detailed work.

Comparison of Low Pressure and Medium Pressure UV Lamps for UV/H2O2Treatment of Natural Waters Containing Micro Pollutants

2010 ◽  
Vol 32 (5) ◽  
pp. 329-337 ◽  
Author(s):  
Guus F. IJpelaar ◽  
Danny J.H. Harmsen ◽  
Erwin F. Beerendonk ◽  
Robin C. van Leerdam ◽  
Debbie H. Metz ◽  
...  
Keyword(s):  
Natural Waters ◽  
Low Pressure ◽  
Medium Pressure ◽  
Uv Lamps ◽  
Micro Pollutants

scholarly journals Potential Repair of Escherichia coli DNA following Exposure to UV Radiation from Both Medium- and Low-Pressure UV Sources Used in Drinking Water Treatment

2002 ◽  
Vol 68 (7) ◽  
pp. 3293-3299 ◽  
Author(s):  
J. L. Zimmer ◽  
R. M. Slawson
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Water Treatment ◽  
Uv Radiation ◽  
Drinking Water Treatment ◽  
Low Pressure ◽  
Plate Count ◽  
Treatment Technology ◽  
Medium Pressure ◽  
Uv Lamp

ABSTRACT The increased use of UV radiation as a drinking water treatment technology has instigated studies of the repair potential of microorganisms following treatment. This study challenged the repair potential of an optimally grown nonpathogenic laboratory strain of Escherichia coli after UV radiation from low- and medium-pressure lamps. Samples were irradiated with doses of 5, 8, and 10 mJ/cm2 from a low-pressure lamp and 3, 5, 8, and 10 mJ/cm2 from a medium-pressure UV lamp housed in a bench-scale collimated beam apparatus. Following irradiation, samples were incubated at 37°C under photoreactivating light or in the dark. Sample aliquots were analyzed for up to 4 h following incubation using a standard plate count. Results of this study showed that E. coli underwent photorepair following exposure to the low-pressure UV source, but no repair was detectable following exposure to the medium-pressure UV source at the initial doses examined. Minimal repair was eventually observed upon medium-pressure UV lamp exposure when doses were lowered to 3 mJ/cm2. This study clearly indicates differences in repair potential under laboratory conditions between irradiation from low-pressure and medium-pressure UV sources of the type used in water treatment.

Bromate formation from the oxidation of bromide in the UV/chlorine process with low pressure and medium pressure UV lamps

Chemosphere ◽  
2017 ◽  
Vol 183 ◽  
pp. 582-588 ◽  
Author(s):  
Jingyun Fang ◽  
Quan Zhao ◽  
Chihhao Fan ◽  
Chii Shang ◽  
Yun Fu ◽  
...  
Keyword(s):  
Low Pressure ◽  
Medium Pressure ◽  
Uv Lamps

Inactivation differences of microorganisms by low pressure UV and pulsed xenon lamps

2003 ◽  
Vol 47 (3) ◽  
pp. 185-190 ◽  
Author(s):  
M. Otaki ◽  
A. Okuda ◽  
K. Tajima ◽  
T. Iwasaki ◽  
S. Kinoshita ◽  
...  
Keyword(s):  
Low Pressure ◽  
High Energy ◽  
Suppressive Effect ◽  
Uv Disinfection ◽  
Xenon Lamp ◽  
Survival Ratio ◽  
E Coli ◽  
High Turbidity ◽  
The Difference ◽  
Uv Lamps

UV disinfection has been applied to water treatment in recent years with low-pressure and medium-pressure UV lamps mainly used as the light source. In general, UV disinfection is considered to be inefficient with water of high turbidity because of inhibition of light penetration. Additionally, photoreactivation may be a problem that should be considered in case a disinfected water is discharged to the environment where sunlight causes reactivation. Recently, other types of lamps have been proposed including a flush-type lamp (such as a pulsed-xenon lamp) that emits high energy and wide wavelength intermittently. In this study, the difference between inactivation efficiencies by low-pressure UV (LPUV) and pulsed-xenon (PXe) lamps was investigated using two coliphage types and three strains of Escherichia coli. PXe had a suppressive effect on photoreactivation rate of the E. coli strains even though there was no significant effect on inactivation rate and maximum survival ratio after photoreactivation. PXe also had a benefit when applied to high turbidity waters as no tailing phenomena were observed in the low survival ratio area although it was observed in LPUV inactivation. This efficiency difference was considered to be due to the difference in irradiated wavelength of both lamps.

scholarly journals Photoreactivation of Escherichia coli after Low- or Medium-Pressure UV Disinfection Determined by an Endonuclease Sensitive Site Assay

2002 ◽  
Vol 68 (12) ◽  
pp. 6029-6035 ◽  
Author(s):  
Kumiko Oguma ◽  
Hiroyuki Katayama ◽  
Shinichiro Ohgaki
Keyword(s):  
Escherichia Coli ◽  
Uv Irradiation ◽  
Genomic Dna ◽  
Uv Disinfection ◽  
E Coli ◽  
Medium Pressure ◽  
Pyrimidine Dimers ◽  
Sensitive Site ◽  
Uv Lamp

ABSTRACT Photoreactivation of Escherichia coli after inactivation by a low-pressure (LP) UV lamp (254 nm), by a medium-pressure (MP) UV lamp (220 to 580 nm), or by a filtered medium-pressure (MPF) UV lamp (300 to 580 nm) was investigated. An endonuclease sensitive site (ESS) assay was used to determine the number of UV-induced pyrimidine dimers in the genomic DNA of E. coli, while a conventional cultivation assay was used to investigate the colony-forming ability (CFA) of E. coli. In photoreactivation experiments, more than 80% of the pyrimidine dimers induced by LP or MPF UV irradiation were repaired, while almost no repair of dimers was observed after MP UV exposure. The CFA ratios of E. coli recovered so that they were equivalent to 0.9-, 2.3-, and 1.7-log inactivation after 3-log inactivation by LP, MP, and MPF UV irradiation, respectively. Photorepair treatment of DNA in vitro suggested that among the MP UV emissions, wavelengths of 220 to 300 nm reduced the subsequent photorepair of ESS, possibly by causing a disorder in endogenous photolyase, an enzyme specific for photoreactivation. On the other hand, the MP UV irradiation at wavelengths between 300 and 580 nm was observed to play an important role in reducing the subsequent recovery of CFA by inducing damage other than damage to pyrimidine dimers. Therefore, it was found that inactivating light at a broad range of wavelengths effectively reduced subsequent photoreactivation, which could be an advantage that MP UV irradiation has over conventional LP UV irradiation.

scholarly journals Demonstration and evaluation of germicidal UV-LEDs for point-of-use water disinfection

2010 ◽  
Vol 8 (3) ◽  
pp. 479-486 ◽  
Author(s):  
Christie Chatterley ◽  
Karl Linden
Keyword(s):  
Uv Irradiation ◽  
Uv Light ◽  
Low Pressure ◽  
Water Disinfection ◽  
Light Emitting ◽  
E Coli ◽  
Point Of Use ◽  
One Year ◽  
Uv Lamps ◽  
Uv Leds

Ultraviolet (UV) irradiation is a common disinfection option for water treatment in the developed world. There are a few systems installed in developing countries for point-of-use treatment, but the low-pressure mercury lamps currently used as the UV irradiation source have a number of sustainability issues including a fragile envelope, a lifetime of approximately one year, and they contain mercury. UV light emitting diodes (LEDs) may offer solutions to many of the sustainability issues presented by current UV systems. LEDs are small, efficient, have long lifetimes, and do not contain mercury. Germicidal UV LEDs emitting at 265 nm were evaluated for inactivation of E. coli in water and compared to conventional low-pressure UV lamps. Both systems provided an equivalent level of treatment. A UV-LED prototype was developed and evaluated as a proof-of-concept of this technology for a point-of-use disinfection option, and the economics of UV-LEDs were evaluated.

Effects of wavelengths of medium-pressure ultraviolet radiation on photolyase and subsequent photoreactivation

2013 ◽  
Vol 13 (1) ◽  
pp. 158-165 ◽  
Author(s):  
Puay Hoon Quek ◽  
Jiangyong Hu
Keyword(s):  
Escherichia Coli ◽  
Uv Radiation ◽  
Spectrophotometric Assay ◽  
Uv Disinfection ◽  
Direct Effects ◽  
Uv Damage ◽  
Simultaneous Exposure ◽  
Medium Pressure ◽  
Repair Ability ◽  
Polychromatic Radiation

This study aims to investigate the effect of different wavelengths (254, 266, 280 and 365 nm) in polychromatic medium-pressure (MP) UV radiation on the ability of photolyases in repairing dimers and discusses its impact on subsequent photoreactivation. Photolyase was exposed to various doses and irradiances of the UV wavelengths and the dimer repair abilities of the irradiated photolyase were determined via a spectrophotometric assay. At wavelengths below 300 nm, dimer repair rates were not influenced by the UV irradiation between 0.03 and 0.10 mW cm−2. For 365 nm, photolyase exhibited enhanced dimer repair at 0.05 mW cm−2 and then reduced dimer repair with increasing irradiance. In addition, photolyase was found to have decreasing dimer repair rates when exposed to increasing UV doses at all tested wavelengths. Lower photoreactivation levels after MP UV disinfection as compared to low-pressure (LP) UV disinfection was not attributable to a single wavelength in the polychromatic radiation, but is possibly due to the simultaneous exposure of photolyase to a broad spectrum of radiation, which led to a reduction in the dimer repair ability of photolyase. This study is the first to report the direct effects of UV radiation on photolyase enzyme. The data in the study provide some evidence for the mechanism for which MP UV disinfection suppresses photoreactivation in Escherichia coli, which has only been speculated on so far. The knowledge from this study will provide a basis upon which to investigate other enzymes involved in the repair of UV damage to DNA.

scholarly journals A standardized method to measure the longitudinal UV emittance of low-pressure-lamps in dependence of water temperature

2021 ◽  
Author(s):  
Alois W. Schmalwieser ◽  
Georg Hirschmann ◽  
Jutta Eggers ◽  
Regina Sommer
Keyword(s):  
Water Temperature ◽  
Low Pressure ◽  
Water Disinfection ◽  
Uv Disinfection ◽  
The Past ◽  
Different Types ◽  
Drinking Water Disinfection ◽  
Standardized Method ◽  
High Level ◽  
Uv Lamps

Abstract The high level of acceptance of ultraviolet (UV) irradiation for water disinfection in the past decade is due to the development of quality standards, especially for drinking water disinfection in Europe (Austrian Standards Institute, German Standards Institute). The central parts of a UV-disinfection device are the UV lamps. Despite their importance, their characterisation and quality assurance is far from being a matter of course and had not been regulated so far. This holds especially with regard to their temperature behaviour. The UV radiation (UVR) emittance of Mercury-Low-Pressure- and Amalgam-Low-Pressure-lamps (LP-lamps) depends on temperature. Each lamp type has its own optimal temperature where UVR emittance is highest. At lower or higher temperatures, UVR emittance is reduced. Additionally LP-lamps do not emit homogeneous along their length and this emission profile can change with temperature. In this paper, we present a standardized method to measure the UVR emittance of LP-lamps along the length in water in dependence of water temperature. This method has been included in the updated Austrian standard ÖNORM M 5873-1 (2020) and in the new release DIN 19294-1 (2020). With this method, the UVR emittance of LP-lamps can be characterized and different types of lamps can be compared.

UV disinfection of wastewater coagulated with ferric chloride: recalcitrance and fouling problems

1998 ◽  
Vol 38 (3) ◽  
pp. 15-23 ◽  
Author(s):  
R. Gehr ◽  
H. Wright
Keyword(s):  
Ferric Chloride ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Uv Disinfection ◽  
Target Level ◽  
Medium Pressure ◽  
Cleaning System ◽  
Uv Lamps ◽  
Collimated Beam ◽  
Pilot Tests

Collimated beam and pilot tests using low pressure or medium pressure UV lamps were conducted to assess the disinfection performance of a municipal wastewater which had been pretreated by ferric chloride coagulation followed by sedimentation. The feed to the UV systems contained high levels of Fe (often above 3 mg/l); suspended solids and UV254 transmission values were also not ideal (mean approximately 30 mg/l and 32% respectively). The collimated beam tests indicated that the target level of 2,500 coliform forming units/100 ml often could not be reached, and the pilot tests revealed significant fouling after only a few hours. Thus physicochemical effluents of this nature likely require upstream filtration (or a relaxation of the target level) and a continual, automated cleaning system to ensure that performance levels can be maintained.

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