Photobiological effects of polychromatic medium pressure UV lamps

2001 ◽  
Vol 43 (4) ◽  
pp. 191-197 ◽  
Author(s):  
Ben F. Kalisvaart
Keyword(s):  
Uv Light ◽  
Biological Effects ◽  
Disinfection Byproducts ◽  
Biological Molecules ◽  
Energy Output ◽  
Irradiation Damage ◽  
Uv Spectrum ◽  
Medium Pressure ◽  
Micro Organisms ◽  
Uv Lamps

Ultraviolet (UV) light has become widely accepted for the disinfection of potable water, process water and wastewater as an alternative to chlorination. To avoid the failure of a UV disinfection system due to the recovery of micro-organisms, certain additional wavelengths in the UV area are emitted by newly developed UV lamps. To reduce the chance of microbial recovery after ultraviolet irradiation, damage must be inflicted in as many areas of the micro-organism as possible. The effective killing of micro-organisms by improved polychromatic medium pressure UV lamps is due to their exceptionally high UV energy output at specific wavelengths across a broad section of the UV spectrum. The combination of these properties results in several different lethal effects in small and large micro-organisms. Important biological molecules other than DNA are likely to be damaged, which helps to prevent the recovery of irradiated micro-organisms. Absorption line spectra of absorbing nucleotide bases, DNA and other biological molecules, including proteins and enzymes, show how effective UV light can be. Recent findings on the biological effects of short wavelengths on Bacillus subtilis, Cryptosporidium parvum and Escherichia coli confirm the effect of short wavelengths. Practical comparisons with conventional low pressure UV lamps at equal UV dosages show better killing rates from polychromatic medium pressure lamps, without formation of disinfection byproducts (DBPs).

Re-use of wastewater: preventing the recovery of pathogens by using medium-pressure UV lamp technology

2004 ◽  
Vol 50 (6) ◽  
pp. 337-344 ◽  
Author(s):  
B.F. Kalisvaart
Keyword(s):  
Wastewater Treatment Plants ◽  
Uv Light ◽  
Low Pressure ◽  
Energy Output ◽  
Uv Spectrum ◽  
Medium Pressure ◽  
Uv Lamp ◽  
Cellular Dna ◽  
Uv Technology ◽  
Term Performance

Ultraviolet (UV) light has become widely accepted as an alternative to chlorination or ozonation for wastewater disinfection. There are now over 2,000 wastewater treatment plants worldwide using either low- or medium-pressure UV technology. Recent studies investigating UV lamp technology, configuration, cleaning requirements and ageing, as well as long-term performance tests, have demonstrated beyond any doubt the effectiveness of UV in inactivating pathogens in wastewater. Research has also shown that, to ensure permanent inactivation and prevent the recovery of microorganisms following exposure to UV, a broad, “polychromatic” spectrum of UV wavelengths is necessary. These wavelengths inflict irreparable damage not only on cellular DNA, but on other molecules, such as enzymes, as well. Only medium-pressure UV lamps produce the necessary broad range of wavelengths; low-pressure lamps emit a single wavelength peak which only affects DNA. Polychromatic medium-pressure UV light is so effective because of the lampÕs exceptionally high UV energy output at specific wavelengths across the UV spectrum. It has been shown, for example, that pathogenic E. coli O175:H7 was able to repair the damage caused by low-pressure UV, but no repair was detected following exposure to UV from medium-pressure lamps.

scholarly journals Analysis of Broadband Antenna Radiation Pulses

2018 ◽  
Vol 22 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Aleksander Cherenkov ◽  
Taras Hutsol ◽  
Igor Garasymchuk ◽  
Jurii Pancyr ◽  
Dmytro Terenov ◽  
...  
Keyword(s):  
Protein Biosynthesis ◽  
Biological Effects ◽  
Pulse Repetition Frequency ◽  
Ultrastructural Changes ◽  
Broadband Antenna ◽  
Resonant Character ◽  
Growth Changes ◽  
Operation Cycle ◽  
Micro Organisms

AbstractElectromagnetic energy can alter metabolic and biosynthetic processes and under certain parameters of pulsed EMF it can change pulse repetition frequency, operation cycle, power, exposure, as well as it can slow down and inhibit cell growth. MW irradiation range of RNA and DNA – containing virus reduces their infectivity. Inhibition of bacterial cultures growth, changes in phagocytic activity of protein biosynthesis, ultrastructural changes in the cells when exposed to EMF EHF. It was found in experiments with micro-organisms that biological effects of EMF on microorganisms wore a resonant character. One of the basic mechanisms of inhibitory action of EHF radiation on harmful microorganisms is the role of membranes in biological reactions of microorganisms on the EMR.

scholarly journals Researching CdZnS/ZnS (GT) Quantum Dots in Cathodoluminescent Mode

2019 ◽  
Vol 8 (9S2) ◽  
pp. 841-843
Keyword(s):  
Quantum Dots ◽  
Research And Development ◽  
Uv Light ◽  
Spectral Characteristics ◽  
Light Sources ◽  
Application Field ◽  
Medium Pressure

Application field of UV light sources is getting larger at the last decades. Among the most widespread are high and medium pressure vacuum lamps. But there currently is a trend of moving away from using mercury both in household applications and manufacturing. This creates a necessity to conduct research and development for UV sources made and operating without Hg. Cathodoluminescent UV sources are in this category. One of the possible ways to create a viable UV anode phosphor is using quantum dots with needed spectral characteristics.

scholarly journals Study of mosquito attractants for photo catalytic mosquito trap

2013 ◽  
Vol 3 (1) ◽  
pp. 14
Author(s):  
Dewi Tristantini ◽  
Slamet ◽  
Angela Jessica Stephanie
Keyword(s):  
Activated Carbon ◽  
Air Temperature ◽  
Heat Production ◽  
Uv Light ◽  
Performance Testing ◽  
Humid Air ◽  
Combination Process ◽  
Photo Catalyst ◽  
Mosquito Trap ◽  
Uv Lamps

Photo catalytic mosquito trap is made of TiO2-Activated Carbon (AC) with a certain composition of AC. Research concerns on the heat spectrum which is produced by combination process of existing CO2 and humid air. The purpose of performance testing is to observe capability of this device in trapping mosquitoes related to the air temperature profile for heat spectrum is play important role for attracting mosquitoes. Result shows photo catalytic mosquito trap is more effective than devices which only consist of UV light or stream of CO2 and the humid air. A number of mosquitoes trapped by the photo catalyst coated panel configuration and UV lamps were lit proved far more effective because the heat production from recombination process. A little difference in temperature can be detected by mosquito. Keywords: Photo Catalytic, Mosquito, Recombination.

The Detection of Near-Ultraviolet Light by Nonmigratory and Migratory Birds

The Auk ◽  
1984 ◽  
Vol 101 (1) ◽  
pp. 53-58 ◽  
Author(s):  
John W. Parrish ◽  
James A. Ptacek ◽  
Kevin L. Will
Keyword(s):  
Migratory Birds ◽  
Uv Light ◽  
Mate Recognition ◽  
Insectivorous Birds ◽  
Uv Spectrum ◽  
Near Ultraviolet ◽  
Ultraviolet Reflectance ◽  
Uv Reflectance ◽  
Uv Vision ◽  
First Time

Abstract Near-ultraviolet (UV) light reception was demonstrated for the first time in three species of nonmigratory emberizid and passerid birds. Behavioral data also established that eight additional alcedinid and emberizid birds can detect near-UV wavelengths. The finding that these more recently evolved species can see near-UV light implies that near-UV vision is probably an important visual capability in most, if not all, diurnal birds. Although the utility of near-UV reception for birds remains equivocal, the fact that nonmigratory as well as migratory birds can perceive UV suggests that birds may be able to utilize the UV spectrum for homing, orientation, and navigation, as do the UV-sensitive arthropods. It also can be inferred that UV vision may be especially useful to insectivorous birds for the detection of UV reflectance patterns, which many otherwise cryptic arthropods possess for mate recognition. Ultraviolet reflectance patterns also may be useful to frugivorous and nectarivorous birds for the detection of food items.

scholarly journals The Effect of Electron versus Hole Photocurrent on Optoelectric Properties of p+-p-n-n+ Wz-GaN Reach-Through Avalanche Photodiodes

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Moumita Ghosh ◽  
Mangolika Mondal ◽  
Aritra Acharyya
Keyword(s):  
Modeling And Simulation ◽  
Wavelength Range ◽  
Reverse Bias ◽  
Flip Chip ◽  
Uv Light ◽  
Avalanche Photodiodes ◽  
Optical Gain ◽  
Uv Spectrum ◽  
Unity Gain ◽  
Visible Blind

The authors have made an attempt to investigate the effect of electron versus hole photocurrent on the optoelectric properties of p+-p-n-n+ structured Wurtzite-GaN (Wz-GaN) reach-through avalanche photodiodes (RAPDs). The photo responsivity and optical gain of the devices are obtained within the wavelength range of 300 to 450 nm using a novel modeling and simulation technique developed by the authors. Two optical illumination configurations of the device such as Top Mounted (TM) and Flip Chip (FC) are considered for the present study to investigate the optoelectric performance of the device separately due to electron dominated and hole dominated photocurrents, respectively, in the visible-blind ultraviolet (UV) spectrum. The results show that the peak unity gain responsivity and corresponding optical gain of the device are 555.78 mA W−1 and 9.4144×103, respectively, due to hole dominated photocurrent (i.e., in FC structure); while those are 480.56 mA W−1 and 7.8800×103, respectively, due to electron dominated photocurrent (i.e., in TM structure) at the wavelength of 365 nm and for applied reverse bias of 85 V. Thus, better optoelectric performance of Wz-GaN RAPDs can be achieved when the photocurrent is made hole dominated by allowing the UV light to be shined on the n+-layer instead of p+-layer of the device.

Photodegradation of sulphadimethoxine in water by medium pressure UV lamp

2008 ◽  
Vol 58 (5) ◽  
pp. 1147-1154 ◽  
Author(s):  
Y. Lester ◽  
I. Gozlan ◽  
D. Avisar ◽  
H. Mamane
Keyword(s):  
Reaction Rate ◽  
Uv Light ◽  
Acid Base ◽  
Direct Photolysis ◽  
Medium Pressure ◽  
Ph Values ◽  
Photodegradation Rate ◽  
Photodegradation Products ◽  
Uv Lamp ◽  
The Impact

The photodegradation rate of sulphadimethoxine (SMT) in water was studied under polychromatic UV light, in a bench scale apparatus. SMT photolysis was carried out at pH levels of 2.5, 6.5 and 10 to study the impact of acid base properties on the degradation of SMT. The highest SMT photolysis fluence based rate was found at pH = 2.5 (k=7.22 × 10−4 cm2/mJ) and the lowest rate at pH = 10 (k=4.72 × 10−4 cm2/mJ), thus the reaction rate decreases with an increase in pH between pH values of 2.5–10. Results indicated that direct photolysis is not satisfactory for degradation of SMT by polychromatic UV lamp as a fluence of approximately 7,000 mJ/cm2 is needed to break down 99% of SMT at pH 6.5. The photodegradation products of SMT were studied at various pH values. Photodegradation of SMT results in dissimilar relative amounts of intermediates formed at different pH values which may exert a photon demand and impact on SMT photodegradation rate.

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 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 Mixing time study in agitated multiple-lamp UV photoreactor using electrical resistance tomography

2021 ◽  
Author(s):  
Zhen Fang Zhao
Keyword(s):  
Electrical Resistance ◽  
Uv Light ◽  
Mixing Time ◽  
Water Disinfection ◽  
Electrical Resistance Tomography ◽  
Rushton Turbine ◽  
Disinfection Process ◽  
Impeller Type ◽  
Uv Lamps ◽  
The Impact

The present study is devoted to the mixing time investigation in a single stirrer UV photoreactor aiming at the drinking water disinfection process. Electrical resistance tomography (ERT) was employed to measure the mixing quality due to the significant advantages. The reactor was a flat-bottomed cylindrical tank with a diameter of 38.1 cm and a height of 60.1 cm fitted with four symmetrically located vertical baffles. The performaces of a 6-blade Rushton turbine and a 4-blade 45° pitched-blade turbine were explored in this study. In the absence of the UV light, four PVC rods were used to replace four UV lamps and evaluate the impact of the locations of the UV tubes on the mixing time. The experimental results demonstrated the feasibility of the ERT system to monitor the mixing process in the UV photoreactor. The ERT results also indicated that the locations of the UV tubes had a signigicant impact on the mixing performance in such a batch stirred tank reactor. Other parameters encompassing the impeller rotational speed the impeller type, and off-bottom clearance were presented with respect to the extensive effects on the mixing time and power consumption.

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