Influence of lamp intensity and water transmittance on the UV disinfection of water

1997 ◽  
Vol 35 (11-12) ◽  
pp. 113-118 ◽  
Author(s):  
R. Sommer ◽  
A. Cabaj ◽  
W. Pribil ◽  
T. Haider
Keyword(s):  
Supply Voltage ◽  
Uv Disinfection ◽  
Uv Detector ◽  
Uv Irradiance ◽  
Flow Through ◽  
Uv Lamp ◽  
Uv Transmittance ◽  
Two Parameters ◽  
Uv Lamps ◽  
Irradiation Chamber

The efficiency of UV disinfection devices depends on flow, lamp intensity and water transmittance. In practice the flow is controlled by suitable methods, whereas the other two parameters, to date, have not been taken into consideration sufficiently. The surveillance of the function of UV disinfection plants is routinely based on a sensor placed on the irradiation chamber wall. This measures changes of UV irradiance without differentiating if the effect is caused by transmittance or lamp intensity so that two different conditions of disinfection may occur at the same sensor readings. We investigated the influence of transmittance vs intensity on disinfection at the same sensor readings in a specially designed laboratory flow through UV irradiation system with one single UV lamp as well as in commercially available UV disinfection plants with multiple UV lamps. All devices were equipped with a calibrated selective UV detector connected to a UV radiometer. Lamp intensity was decreased by diminishing the supply voltage. UV transmittance was reduced by pumping aqueous sodium thiosulphate solution into the water inflow. The disinfection capacity was determined by measuring the reduction equivalent doses (RED) using a standardised biodosimetric method. We showed that equal sensor readings, either achieved by reducing the lamp intensity or by lowering the UV transmittance of the water, resulted in different REDs in one-lamp systems. The diminishing of UV intensity caused a greater decrease of REDs than reducing the water transmittance. However, in the multiple-lamp systems tested, equal sensor readings yielded equal REDs.

Method to determine the power efficiency of UV disinfection plants and its application to low pressure plants for drinking water

2016 ◽  
Vol 17 (4) ◽  
pp. 947-957 ◽  
Author(s):  
Alois W. Schmalwieser ◽  
Georg Hirschmann ◽  
Alexander Cabaj ◽  
Regina Sommer
Keyword(s):  
Drinking Water ◽  
Electric Power ◽  
Power Efficiency ◽  
Electrical Power ◽  
Low Pressure ◽  
Uv Disinfection ◽  
Plant Type ◽  
Uv Irradiance ◽  
Flow Through ◽  
Selection Of

In this paper we present a method to determine the power efficiency of ultraviolet (UV) disinfection plants and apply this to low pressure plants for drinking water. In UV disinfection plants the water flow is regulated to ensure that microorganisms receive the necessary fluence for inactivation while passing through. The flow depends on the UV transmission (UVT) of the water. The lower the UVT of the water is, the less water may flow through the plant. UV irradiance is produced by lamps that consume, together with other components, electrical power and entail running costs. The power efficiency – electrical power versus disinfected volume – of a plant has therefore an important impact. Applying this method to different UV plants that are on the market shows that electric power of at least 5.3 Wh is necessary to disinfect 1 m3 of water possessing a UVT of 80% (100 mm), 8 Wh at 50% and 22 Wh at 10%. Further we found that ineffective design or a wrong selection of a plant may enhance these values by a factor of up to 7. This method enables not only the calculation of the power efficiency but also the decision for a certain plant type.

scholarly journals Laboratory Investigation of Inorganic Fouling of Low Pressure UV Disinfection Lamps

2001 ◽  
Vol 36 (1) ◽  
pp. 71-92 ◽  
Author(s):  
M. Sheriff ◽  
M. Gehr
Keyword(s):  
Uv Light ◽  
Low Pressure ◽  
Bulk Precipitation ◽  
Batch Tests ◽  
Uv Irradiance ◽  
Theoretical Predictions ◽  
Flow Through ◽  
Inorganic Constituents ◽  
Uv Lamps ◽  
Solids Deposition

Abstract Iron(III) (mainly dosed as FeCl3) is one of the main inorganic constituents associated with the fouling of UV lamps during disinfection of wastewater. A low pressure mercury lamp UV system was operated under laboratory conditions to assess the effects of heat and UV light on fouling. Iron(III) was dosed at different concentrations and fouling was monitored by measuring the UV irradiance. The potential for ferric phosphate fouling and the effects of organics were also studied. Results showed that fouling did not occur in recirculating systems over 12 days of observation. However, in flow-through systems, the extent and rate of fouling depended on the solution Fe concentration. Furthermore, addition of phosphorus increased the fouling rate. Bulk precipitation appeared to be significant at iron(III) dosing over 3 mg/L. Theoretical predictions of an equilibrium model (MINEQL+) showed similar trends with measured concentrations of soluble Fe and P from batch tests. However, model predictions of temperature effects alone could not account for the observed solids deposition on the quartz sleeve. Bulk precipitation, followed by sedimentation, was considered to be the dominant mechanism at high iron (III) concentrations.

The spectral UV sensitivity of microorganisms used in biodosimetry

2002 ◽  
Vol 2 (3) ◽  
pp. 175-181 ◽  
Author(s):  
A. Cabaj ◽  
R. Sommer ◽  
W. Pribil ◽  
T. Haider
Keyword(s):  
Spectral Sensitivity ◽  
Uv Radiation ◽  
Survival Curves ◽  
Uv Sensitivity ◽  
Sensitivity Curves ◽  
Bacillus Subtilis Atcc ◽  
Flow Through ◽  
The Mean ◽  
Two Parameters ◽  
Uv Lamps

Biodosimetry, that is the application of microorganisms for the measurement of radiation, is already in wide use in the field of UV disinfection. The measurement of the mean fluence in flow-through systems with a biodosimeter (microorganisms with calibrated UV sensitivity) results in the Reduction Equivalent Fluence (REF). In the case of quasi monochromatic radiation (mercury low pressure lamp, 253.7 nm), the flow pattern of the water through the inhomogeneous radiation field, together with some other parameters, strongly influences the REF but the spectral sensitivity of the biodosimeter plays no role. If microorganisms with shouldered survival curves are used as biodosimeters two parameters (k and d) are necessary to describe their survival curves. In general, both parameters are wavelength dependent and the functions k(λ) and d(λ) must be known if medium pressure mercury lamps are used, which emit polychromatic UV radiation. The knowledge of k(λ) also is necessary for selecting an appropriate UV sensor which controls the function of the UV lamps during the operation of the disinfection plant. In literature many different spectral sensitivity curves were published but they all differ somehow. The functions k(λ) and d(λ) were measured for spores of Bacillus subtilis ATCC 6633 in using quasi-monochromatic UV radiation and the results were tested in using polychromatic UV radiation.

Chemical effects on UV irradiation absorption of fouled quartz sleeves in ultraviolet disinfection

2008 ◽  
Vol 8 (2) ◽  
pp. 217-222 ◽  
Author(s):  
Beibei Zhu Sun ◽  
Ernest Blatchley ◽  
Mike Oliver ◽  
Cheng Zheng ◽  
Kristofer Jennings
Keyword(s):  
Statistical Analysis ◽  
Uv Disinfection ◽  
Uv Absorbance ◽  
Ultraviolet Disinfection ◽  
High Chemical ◽  
Chemical Surface ◽  
Chemical Effects ◽  
Uv Transmittance ◽  
Main Effects ◽  
Iron And Manganese

The effects of foulant chemical composition on ultraviolet (UV) absorbance of fouled quartz sleeves in UV disinfection systems were studied. Statistical analysis was conducted to examine the effects of nine fouling chemicals on the UV transmittance changes of fouled quartz lamp sleeves. The results demonstrated that the main effects were attributable to surface concentrations of iron and manganese. The surface concentrations of calcium and copper had no significant effects on the UV absorbance of fouled sleeves. The interaction effects of copper with iron and magnesium with manganese were also revealed from the statistical analysis. The model is able to give reasonable predictions of the UV absorbance characteristics of foulants from other UV systems. However, several limitations of this model were identified. First, the model does not accurately predict the absorbance at relatively high chemical surface concentrations. Second, the model does not account for the possible effects of anions and organics on UV absorption of fouled quartz sleeves.

scholarly journals Don't Let Ultraviolet Hurt Your Eyes During SARS-CoV-2 Disinfection: A Retrospective Observational Study

2021 ◽  
Author(s):  
Liuxueying Zhong ◽  
Rongjiao Liu ◽  
Jingyi Peng ◽  
Wanwen Shao ◽  
Xiaofeng Lin ◽  
...  
Keyword(s):  
Observational Study ◽  
Questionnaire Survey ◽  
Preventive Measures ◽  
Retrospective Observational Study ◽  
Control Group ◽  
Equivalent Control ◽  
Eye Damage ◽  
Uv Lamp ◽  
Uv Lamps ◽  
At Home

Abstract Purpose: A retrospective observational study was carried on to investigate whether UV lamp will increase the risk of eye damage by comparing the exposure factors leading to ultraviolet keratitis (UVK) during the epidemic of COVID-19 and the control group in 2019.Methods: Data on UVK patients with clear exposure histories and typical symptoms were gathered. The date acquisition refers to the most crucial period in fighting the COVID-19 pandemic (24 January to 29 February in 2020, crucial period for short) in China, while the equivalent control 37- day period in 2019 refers to the period from 4 February to 12 March (control group for short). The detailed information of UVK cases were gathered through questionnaire survey, including injury photosources, ultraviolet applications, onset locations. Results: This retrospective observational study of 81 patients revealed that the number of UVK cases during crucial period 1 was threefold higher (n=61 patients) than control group (n=20 patients). All cases who recorded injury photosources were injury by UV lamps during crucial period, while by UV lamps (61.54%) or welding (38.46%) during control group. There were more than 70% of UVK cases injured at home by household UV lamps during crucial period, while were 15.38% during control group. They are significant differences in UVK photosource and exposure location between 2 groups (P<0.001).Conclusion: Household UV lamp users should be informed about possible UVK risk and of relevant preventive measures. Government and media should guide people use household disinfection items rationally and safely.

scholarly journals E. coli Inactivation Kinetics Modeling in a Taylor-Couette UV Disinfection Reactor

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
M. L. Palacios-Contreras ◽  
F. Z. Sierra-Espinosa ◽  
K. Juárez ◽  
S. Silva-Martínez ◽  
A. Alvarez-Gallegos ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Polynomial Equation ◽  
Microbial Inactivation ◽  
Uv Disinfection ◽  
Order Kinetic ◽  
E Coli ◽  
Toroidal Vortices ◽  
Angular Velocities ◽  
Uv Lamp ◽  
Kinetics Of

A simple model was developed to predict the survival behavior of E. coli subjected to UV disinfection in a Taylor-Couette reactor. The model includes the CFD evaluation of the counterrotating toroidal vortices developed within the annular space of two coaxial cylinders. The UV lamp was located within the diameter of the internal rotating cylinder. The residence time of the bacteria near the UV lamp is, therefore, a function of both the size of the vortex and its angular velocity. The effect of angular velocity on the formation of counterrotating toroidal vortices and their impact on the kinetics of UV microbial inactivation was experimentally evaluated. The kinetics of microbial inactivation follow an apparent first-order kinetic equation between 300 and 2000 revolutions per minute. Therefore, in this range of angular velocities, a set of k values (indirectly taking into account the hydrodynamic pattern and UV irradiance) was obtained for a given concentration of bacteria. Then, the set of k values was correlated with the range of angular velocities applied using the polynomial equation. A k value can be obtained for an unknown angular velocity through the polynomial equation. Therefore, a simulation curve of microbial inactivation can be obtained from the first-order kinetic equation. The efficiency of bacteria removal improves depending on the angular velocity applied. A good agreement is observed between the simulation of the survival behavior of the microorganisms subjected to UV disinfection with the experimental data.

Microbicidal effect of reflected UV radiation in devices for water disinfection

1996 ◽  
Vol 34 (7-8) ◽  
pp. 173-177 ◽  
Author(s):  
R. Sommer ◽  
A. Cabaj ◽  
T. Haider
Keyword(s):  
Stainless Steel ◽  
Uv Radiation ◽  
Multiple Reflection ◽  
Water Disinfection ◽  
The Other ◽  
Uv Disinfection ◽  
Operating Life ◽  
Inner Surface ◽  
Relative Extent ◽  
Irradiation Chamber

A standardised biodosimetric method was used to quantify the influence of reflection on the reduction equivalent UV doses (RED) in two commercially available water disinfection systems. One device, possessing a reflector made of aluminium, showed a decrease of RED of about 40% after removing the reflector. In the other plant, made of stainless steel, the inner surface of the irradiation chamber served as a reflector by itself. After eliminating the reflectance by black lacquering the inner surface of the irradiation chamber a distinctive decrease of RED was measured. This effect depended on the transmittance of the water (253.7 nm). With increasing water transmittance an increasing relative loss of RED was observed. The results showed that the relative extent of the RED caused by reflection may even exceed the reflectance of the material due to multiple reflection, especially in water with high transmittance. However, in UV disinfection plants with inner surfaces made of reflecting material the reflectance may decrease during the operating life. Therefore, measuring the extent of reflection influencing the RED by using a suitable biodosimetric method is essential in UV devices for water disinfection.

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.

254 nm Radiant Efficiency of High Output Low Pressure Mercury Discharge Lamps with Neon-Argon Buffer Gas

2013 ◽  
Vol 325-326 ◽  
pp. 409-412
Author(s):  
Hao Jun Zhang ◽  
Qiu Yi Han ◽  
Shan Duan Zhang
Keyword(s):  
Mercury Vapor ◽  
Low Pressure ◽  
Input Power ◽  
Cold Spot ◽  
Outer Diameter ◽  
Buffer Gas ◽  
Uv Irradiance ◽  
Radiant Efficiency ◽  
Uv Lamps ◽  
High Output

High output low pressure mercury (LPM) discharge UV lamps have been briefly introduced. In order to measure the 254 nm radiant efficiency simply and preciously, Keitz formula was used and its advantage was illustrated. The LPM lamps had outer diameter of 19 mm (T6). The buffer gases are neon (65%) and argon (35%) with total pressure 1-10 Torr (133-1333 Pa). The lamps were operated with cold spot temperatures from 20°C to 80°C and discharge current from 0.8 A to 2.0 A. The electric field, input power, 254 nm UV irradiance and irradiance of other Hg lines from 265 to 579 nm in positive column were measured. The radiant power of each wavelength can be calibrated according to the 254 nm output and the Keitz formula. It was shown that the radiant efficiency of 254 nm can reach a maximum of above 40% at cold spot temperature 45-47 °C and current 1.6 A for filling pressure less than 3 Torr. The optimal mercury vapor pressure was 1.2 to 1.4 Pa. The output percentage of other Hg lines was below 5%. With the decrease of buffer gas pressure, the 254 nm radiant efficiency increased obviously.

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