scholarly journals Comparison of indicator bacteria inactivation by the ultraviolet and the ultraviolet/hydrogen peroxide disinfection processes in humic waters

2011 ◽  
Vol 9 (4) ◽  
pp. 659-669 ◽  
Author(s):  
Arzu Teksoy ◽  
Ufuk Alkan ◽  
Sevil Çalışkan Eleren ◽  
Burcu Şengül Topaç ◽  
Fatma Olcay Topaç Şağban ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Fulvic Acid ◽  
Uv Radiation ◽  
Surface Waters ◽  
Uv Light ◽  
Indicator Bacteria ◽  
E Coli ◽  
Bacteria Inactivation ◽  
Potential Indicator ◽  
Test Organisms

The aim of the present study was to evaluate responses of potential indicator bacteria (i.e. Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis) to the ultraviolet (UV) radiation and the UV/hydrogen peroxide (H2O2) disinfection processes of surface waters with different qualities in terms of humic content. The UV and the UV/H2O2 processes were applied to waters containing various concentrations of fulvic acid in order to inactivate E. coli, P. aeruginosa and B. subtilis spores. Three fulvic acid (0, 2 and 6 mg l−1) and four H2O2 (0, 10, 25 and 50 mg l−1) concentrations were used. Results showed that the k values of E. coli, P. aeruginosa and B. subtilis spores varied between 2.22 and 4.00, 1.73 and 3.58, and 1.40 and 1.86, respectively, in all test conditions. The sensitivity of the test organisms followed a decreasing order of E. coli > P. aeruginosa > B. subtilis. Results of the study indicated that the blocking effect of fulvic acid for the UV light was diminished by using H2O2 in combination with the UV radiation. Findings of the present study strongly suggested that the UV/H2O2 process was significantly effective on the inactivation of E. coli and P. aeruginosa in humic waters, whereas it induced little or no apparent contribution to the disinfection efficiency of B. subtilis spores.

Destruction of Pollutants and Microorganisms in Water by UV Light and Hydrogen Peroxide

1992 ◽  
Vol 27 (1) ◽  
pp. 57-68 ◽  
Author(s):  
D.W. Sundstrom ◽  
B.A. Weir ◽  
T. A. Barber ◽  
H. E. Klei
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Compounds ◽  
Chemical Structure ◽  
Uv Light ◽  
Liquid Films ◽  
Strong Interactions ◽  
Order Kinetic ◽  
E Coli ◽  
Order Kinetic Model ◽  
Catalyzed Oxidation

Abstract This project investigated the destruction of organic compounds and microorganisms in water by ultraviolet catalyzed oxidation using hydrogen peroxide as the oxidizing agent. The combination of UV light and hydrogen peroxide was effective in decomposing all of the organic compounds studied. The rates of destruction increased with increasing peroxide concentration and UV light intensity, and were highly dependent on chemical structure. The destruction of mixtures of organic compounds showed strong interactions between reacting components. The inactivation of E. coli and B. subtilis spores by UV light and/or hydrogen peroxide was studied in flat plate reactors. By using thin liquid films, the combination of UV light and peroxide greatly increased the rates of inactivation of both microorganisms. The results were correlated by a mixed second order kinetic model.

Effect of advanced oxidation processes on inactivation of coliphages

1995 ◽  
Vol 31 (5-6) ◽  
pp. 131-134 ◽  
Author(s):  
Ritva L. Rajala-Mustonen ◽  
Helvi Heinonen-Tanski
Keyword(s):  
Hydrogen Peroxide ◽  
Uv Radiation ◽  
Advanced Oxidation Processes ◽  
Uv Light ◽  
Tap Water ◽  
Ozone Treatment ◽  
Batch Experiments ◽  
Phage Titer ◽  
Phage Types ◽  
Dna And Rna

Chlorine and its derivatives are no longer regarded as acceptable disinfectants of water because of compounds they form with organic material in water. These compounds have been proved to be mutagenic and carcinogenic to man. Alternative disinfectants like UV radiation and ozonization are regarded as less harmful disinfectants of microorganisms in water. In the present study the effect of UV radiation alone and together with hydrogen peroxide, and ozone treatment on the inactivation of coliphages in tap water were studied. Two phage types, DNA- and RNA-phages were seeded into tap water and exposed to these disinfectants in batch experiments. The inactivation of phages was determined as a reduction of phage titer as a function of contact time. Disinfection with ozone proved to inactivate coliphages more rapidly than UV light or UV light together with hydrogen peroxide (H2O2). After two minutes exposure time the reduction in phage titer was from 6 to 8 log units with ozone while with UV light or UV with H2O2 the reduction was from three to four log units. According to these results ozonization seemed to be more efficient disinfectant than UV light radiation.

scholarly journals Faecal indicator bacteria and antibiotic-resistant β-lactamase producing Escherichia coli in blackwater: a pilot study

2019 ◽  
Vol 70 (2) ◽  
pp. 140-148 ◽  
Author(s):  
Urška Šunta ◽  
Miha Žitnik ◽  
Noemi Concetta Finocchiaro ◽  
Tjaša Griessler Bulc ◽  
Karmen Godič Torkar
Keyword(s):  
Pilot Study ◽  
Clavulanic Acid ◽  
Uv Light ◽  
Indicator Bacteria ◽  
Resistant Bacteria ◽  
Faecal Indicator Bacteria ◽  
Antibiotic Resistant ◽  
Separation Unit ◽  
E Coli ◽  
Gastrointestinal Bacteria

AbstractThe aim of this study was to identify and quantify faecal indicator bacteria in blackwater collected from a source separation unit and determine the amount of E. coli isolates resistant to antimicrobials and their potential to produce extended spectrum β-lactamases (ESβLs) and metallo-β-lactamases (MβLs), which hydrolyse the most important antibiotics used in clinical practice. Most of the isolates were resistant to amoxicillin with clavulanic acid (36.4 %), followed by ticarcillin with clavulanic acid (22.7 %) and tetracycline (18.2 %). ESβL-producing genes blaCTX-M and blaTEM were found in three (13.6 %) and four (18.2 %) E. coli strains, respectively, while MβL genes were found in two (9.1 %). By separating at source, this pilot study clearly shows that gastrointestinal bacteria of healthy people can be an important source of antibiotic resistance released into the environment through wastewaters. One way to prevent that is to treat wastewater with a combination of TiO2, UV light, or ozone, as successful methods to remove resistant bacteria and prevent their spread in the environment.

scholarly journals Escherichia coli as a potential indicator of Biebrza River enrichment sources / Escherichia coli jako potencjalny wskaźnik wzbogacania wód rzeki Biebrzy

2013 ◽  
Vol 19 (1) ◽  
pp. 31-37
Author(s):  
Magdalena Frąk
Keyword(s):  
Escherichia Coli ◽  
Surface Waters ◽  
Background Level ◽  
Water Levels ◽  
Organic Contamination ◽  
E Coli ◽  
Escherichia Coli Cells ◽  
Potential Indicator ◽  
Chemical Water ◽  
Number Of Bacteria

Abstract The number of Escherichia coli cells in the waters of the Biebrza River was analyzed. The results were compared with the values of select chemical water quality indicators and with the Biebrza River catchment development. Organic contamination was detected along the entire run of the River and was caused by the presence of substances washed off the adjacent marshy areas and the influx of household and agricultural wastewaters. The highest number of bacteria was found in the Middle and Lower Basins of the Biebrza River. The incease in the number of E. coli in the spring to over 24 MPN·cm-3 is a result of the numerous presence of water birds in the area of the National Park. Of consequence are also meltwaters that introduce contamination from peat lands into the watercourse. The increased number of E. coli cells in the summer is related to runoff from the areas along the River with numerous farms and dairy cattle pastures. The number of bacteria in the river is most probably influenced by changes in water levels and types of accumulated sediment. The Escherichia coli count allows determining the source of the contamination of surface waters, which is of particular significance for planned water management on protected areas. The number of E. coli below 7 MPN·cm-3 in the waters of the Biebrza River is at the natural background level, whereas counts of over 24 MPN·cm-3 are related to the influx of household wastewaters.

Photosensitization of Escherichia coli and Saccharomyces cerevisiae by phenylheptatriyne from Bidens pilosa

1980 ◽  
Vol 26 (6) ◽  
pp. 698-705 ◽  
Author(s):  
Thor Arnason ◽  
Chi-Kit Wat ◽  
Kelsey Downum ◽  
Etsuo Yamamoto ◽  
Elizabeth Graham ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Singlet Oxygen ◽  
Uv Radiation ◽  
Theory Model ◽  
Survival Curves ◽  
Bidens Pilosa ◽  
E Coli ◽  
Test Organisms

The photosensitizing action of 7-phenylhepta-2,4,6-triyne (PHT), a polyacetylenic compound isolated from Bidens pilosa L. (Asteraceae), has been studied using Escherichia coli and Saccharomyces cerevisiae as the test organisms. The survival curves for E. coli treated with PHT and ultraviolet (UV) radiation were obtained and have been interpreted quantitatively on the basis of a target theory model. The number of "targets" in the cell that must be destroyed before cell death occurs was estimated at six, whereas the dose, D0, that reduced the surviving fraction of the population to 1/e of its value was estimated to be 280 J/m2.Survival was enhanced in aerobic conditions as compared with anaerobic conditions, which is strong evidence that PHT does not behave as a photodynamic sensitizer in vivo. This view was confirmed by work with azide (a quencher of singlet oxygen), D2O (which increases the lifetime of singlet oxygen), and superoxide dismutase (which scavenges superoxide radicals). None of these treatments modified the survival curves significantly, indicating that activated species of O2 are probably not involved in photosensitizations with PHT in vivo.Cell respiration was found to be rapidly inhibited by mild treatments of PHT and UV radiation, suggesting that nuclear metabolism is not the primary target of photosensitization as is the case with another group of photosensitizers, the furanocoumarins. The available evidence indicates that PHT is a representative of a new class of phototoxic compounds. A mechanism of action involving production of free radicals is proposed.

scholarly journals Study on DNA damages induced by UV radiation

2015 ◽  
Vol 5 (4) ◽  
pp. 16-22
Author(s):  
Hong Van Doan ◽  
Ba Tuan Dinh ◽  
Tuan Anh Tran ◽  
Thuy Ngan Nguyen ◽  
Bich Thuan Ta ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Uv Light ◽  
Protective Effects ◽  
Dna Damages ◽  
Growth And Survival ◽  
E Coli ◽  
Pyrimidine Dimers ◽  
Induced Mutants ◽  
Radiation Induced ◽  
Selection Of

DNA damages in Escherichia coli (E. coli) exposed to UV radiation have been investigated. After 30 min of exposure to UV radiation of 5 mJ/cm2, the growth of E. coli in LB broth medium was about only 10% in compared with non-irradiated one. This results suggested that the UV radiation caused the damages for E. coli genome resulted in reduction in its growth and survival, and those lesions can be somewhat recovered. For both solutions of plasmid DNAs and E. coli cells containing plasmid DNA, this dose also caused the breakages on single and double strands of DNA, shifted the morphology of DNA plasmid from supercoiled to circular and linear forms. The formation of pyrimidine dimers upon UV radiation significantly reduced when the DNA was irradiated in the presence of Ganoderma lucidum extract. Thus, studies on UV-induced DNA damage at molecular level are very essential to determine the UV radiation doses corresponding to the DNA damages, especially for creation and selection of useful radiation-induced mutants, as well as elucidation the protective effects of the specific compounds against UV light.

Time dose reciprocity in UV disinfection of water

1998 ◽  
Vol 38 (12) ◽  
pp. 145-150 ◽  
Author(s):  
R. Sommer ◽  
T. Haider ◽  
A. Cabaj ◽  
W. Pribil ◽  
M. Lhotsky
Keyword(s):  
Uv Irradiation ◽  
Uv Light ◽  
Water Disinfection ◽  
High Dose ◽  
E Coli ◽  
Dose Rates ◽  
Test Organisms ◽  
Irradiation Apparatus ◽  
Uv Dose ◽  
Time Dose

The microbicidal effect of UV light depends on the dose in both, disinfection processes and natural inactivation by the sunlight in surface water. Deviations of the time dose reciprocity are well known from chemical water disinfection whereas no data are available about this effect in UV inactivation in water. In a previous study we found that the UV inactivation behaviour of yeast strains does not follow the time dose reciprocity, insofar that longer exposure led to higher reduction of cultivable cells. In contrast, an earlier study about E coli B/r claimed a higher inactivation with single exposure compared with fractionated UV irradiation. To investigate this question we selected water-relevant microorganisms and studied their UV inactivation behaviour (253.7nm) by means of a specially designed UV irradiation apparatus (a) under standard irradiation conditions (2W/m2) and (b) with three levels of UV dose rate (2, 0.2 and 0.02W/m2). The test organisms were (i) three E coli strains (ATCC 25922, ATCC 11229 and an isolate from sewage) representing the routinely used faecal indicator, (ii) three bacterial viruses (MS2, ϕX174 and B40-8) proposed as indicators for viral contamination in water and (iii) spores of Bacillus subtilis because of their use as a biodosimeter in prototype testing of commercial UV plants for drinking water disinfection. We found, under standard inactivation conditions, that the E coli strains and phage ϕX174 are most UV susceptible, followed by B40-8 and finally MS2 and bacterial spores. The dose protraction experiments revealed for the E coli strains a higher inactivation with high dose rates compared to low dose rates at the same UV doses (difference of about 1 log10 at 80-100J/m2). The other test organisms did not deviate from the time dose reciprocity in the proven range of dose.

scholarly journals Population similarity of enterococci and Escherichia coli in surface waters: A predictive tool to trace the sources of fecal contamination

2006 ◽  
Vol 4 (3) ◽  
pp. 347-356 ◽  
Author(s):  
W. Ahmed ◽  
R. Neller ◽  
M. Katouli
Keyword(s):  
Escherichia Coli ◽  
Surface Waters ◽  
Water Samples ◽  
Animal Species ◽  
Fecal Contamination ◽  
Indicator Bacteria ◽  
Similarity Analysis ◽  
Wet Season ◽  
E Coli ◽  
Dry Seasons

A biochemical fingerprinting method (the PhPlate system) was used to compare similarities between Escherichia coli and enterococci populations from surface water samples with those found in different animal species during the wet and the dry seasons in order to predict the dominant source(s) of fecal contamination in a local creek. A significant increase in the number and diversity of enterococci was observed in the creek during the wet season. Enterococci population from water samples also showed a higher population similarity with animal species than did E. coli. A higher population similarity was found between both indicator bacteria and animal species during the wet season with highest population similarities found in dogs, horses, cows and kangaroos. In contrast, a low population similarity was found for both fecal indicator bacteria from humans with water samples during the wet and the dry seasons, indicating that humans are not a major source of contamination in the studied creek. The results also indicate that the population similarity analysis of enterococci population has an advantage over E. coli in tracing the possible source(s) of contamination in the studied creek and that population similarity analysis as used in this study can be used to predict the source(s) of fecal contamination in surface waters.

scholarly journals UV light induced DNA damages and the radiation protection effects of Lingzi mushrom extract

2016 ◽  
Vol 6 (3) ◽  
pp. 40-47
Author(s):  
Thuong Lan Vo Thi ◽  
Ba Tuan Dinh ◽  
Bich Thuan Ta ◽  
Bang Diep Tran ◽  
Minh Quynh Tran
Keyword(s):  
Uv Radiation ◽  
Molecular Level ◽  
Uv Light ◽  
Protective Effects ◽  
Dna Damages ◽  
Protection Effect ◽  
Taq Polymerase ◽  
E Coli

UV light has strongly influenced on the growth of E. coli as well as caused DNA damages. Configurations of both genomic DNA and pUC 19 plasmids extracted from E. coli were significantly changed by the exposure to UV light of 254 nm and DLT, an extract of Ganoderma lucidum Lingzi mushroom. The results also revealed the radio-protective effects of DLT to UV radiation. By adding 2% DLT to its culturing suspension, the growth of E. coli was significantly decreased, whereas a low DLT amount of about 0.5% slightly improved its growth, indicated that the DLT extract can be used as a promising protective substance against UV radiation. At the molecular level, the radio-protective effects of DLT were observed for both UV treated DNA and protein. Thus, DLT can protect DNA in vivo, but not in vitro. This effect was also observed for Taq polymerase, suggested that the radio-protection effect of DLT may due to it accelerated the degradation of radicals or species that produced in the suspensions during UV exposure.

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