Evaluation of the UV disinfection process in bacteria and amphizoic amoebae inactivation

2003 ◽  
Vol 3 (4) ◽  
pp. 285-291 ◽  
Author(s):  
C. Maya ◽  
N. Beltrán ◽  
B. Jiménez ◽  
P. Bonilla
Keyword(s):  
Uv Light ◽  
Salmonella Typhi ◽  
Secondary Effluent ◽  
Disease Response ◽  
Log Reduction ◽  
Treated Effluent ◽  
Disinfection Process ◽  
High Concentrations ◽  
Uv Dose ◽  
Higher Doses

Every year around 3.4 million people die from water-related diseases, mainly amoebiasis and diarrhoea caused by bacteria. The assessment of the efficiency of a UV light disinfection process in the inactivation of indicators, pathogen bacteria and amphizoic amoebae in a secondary treated effluent was carried out. Wastewater was irradiated with different doses of UV light using a collimated-beam reactor. Dose-response results showed that a UV dose of 15 mW·s/cm2 was enough to inactivate FC to the limit established in Mexican legislation (<1,000 MPN/100 ml) for irrigation reuse, as well as reaching a 2 log inactivation for faecal streptococci. Also, the final concentration reached for Salmonella typhi was <103 MPN, which is the minimal concentration for a disease response in humans. The isolation from the secondary effluent and the pathogenicity determination of Acanthamoeba were carried out. Amoebae were concentrated to higher concentrations than those of the effluent for irradiation tests. Radiation tests showed that amoebae required higher doses than bacteria for their total inactivation (60 mW·s/cm2 for a 2 log reduction). Results showed that UV light is an alternative to inactivate high contents of bacteria and amoebae trophozoites, although higher doses were needed for the high concentrations of amoebae used.

Inactivation of recalcitrant protozoan oocysts and bacterial endospores in drinking water using high-intensity pulsed UV light irradiation

2012 ◽  
Vol 12 (4) ◽  
pp. 513-522 ◽  
Author(s):  
J. C. Hayes ◽  
M. Garvey ◽  
A. M. Fogarty ◽  
E. Clifford ◽  
N. J. Rowan
Keyword(s):  
High Intensity ◽  
Uv Light ◽  
Waste Water Treatment ◽  
Scale Up ◽  
Clear Trend ◽  
E Coli ◽  
Log Reduction ◽  
Bacterial Endospores ◽  
Pulsed Uv Light ◽  
Uv Dose

This constitutes the first study to compare the use of high-intensity pulsed UV light (PUV) irradiation for the novel destruction of harmful protozoan (Cryptosporidium parvum Iowa isolate) oocysts and bacterial (Clostridium perfringens ATCC 13124 and Bacillus cereus ATCC 11178) endospores in artificially-spiked water where these organisms are resistant to conventional chlorination. Experimental results revealed that all three test organisms in their dormant recalcitrant state required extended levels of pulsing to achieve significant reductions in numbers compared to other similarly PUV-treated Escherichia coli ATCC 25922 that is a non-spore forming indicator of faecal pollution in water. 120 pulses at 900 V or 16.2 J per pulse (equivalent to a UV dose of 8.39 μJ cm−2) were required to achieve ca. 2 log C. perfringens spore numbers, whereas a similar level of PUV irradiation reduced both C. parvum oocysts and B. cereus endospores by ca. 5 log orders. A comparative ca. 5 log reduction of E. coli cell numbers was achieved after only 25 pulses at 900 V (equivalent to a UV dose of 1.74 μJ cm−2). A clear trend emerged where the order of resistance to PUV-irradiation observed was C. perfringens endospores > C. parvum oocysts, B. cereus endospores > E. coli cells. This study suggests disinfection kinetic data for the more resistant C. perfringens endospores can be used as a measure of estimating disinfection efficacy of PUV treatments for C. parvum oocysts in water, avoiding the need to use complex animal or cell culture infectivity models that are only available in specialised laboratories with highly trained technicians. This study will inform future studies exploring scale-up of PUV at waste-water treatment plants.

An antimicrobial polycationic sand filter for water disinfection

2011 ◽  
Vol 63 (9) ◽  
pp. 1997-2003 ◽  
Author(s):  
Annalisa Onnis-Hayden ◽  
Bryan B. Hsu ◽  
Alexander M. Klibanov ◽  
April Z. Gu
Keyword(s):  
Treatment Plant ◽  
Antimicrobial Properties ◽  
Bacterial Count ◽  
Water Disinfection ◽  
Aqueous Sample ◽  
Secondary Effluent ◽  
E Coli ◽  
Log Reduction ◽  
Disinfection Process ◽  
Aqueous Effluent

A new sand filtration water disinfection technology is developed which relies on the antimicrobial properties of hydrophobic polycations (N-hexylated polyethylenimine) covalently attached to the sand's surface. The efficacy of the filter disinfection process was evaluated both with water spiked with E. coli and with real aqueous effluent from a wastewater treatment plant. For the former, over 7-log reduction in bacterial count was achieved. With real environmental wastewater secondary effluent samples, the E. coli concentration reduction declined to under 2 logs. This reduced inactivation efficiency compared to the model aqueous sample is likely due to the particulate or colloidal matter present that diminishes the contact between the immobilized polycation and the suspended bacteria. Preliminary sand washing methods were tested to assess potential ‘regeneration’ approaches. Potential advantages of the proposed approach over conventional disinfection in terms of eliminating harmful by-products and reducing energy consumption are discussed.

Ozonation of a secondary effluent both for fresh water protection and re-use

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
M. Antonelli ◽  
V. Mezzanotte ◽  
C. Nurizzo
Keyword(s):  
Contact Time ◽  
Pilot Scale ◽  
Secondary Effluent ◽  
Water Protection ◽  
Faecal Coliforms ◽  
Colour Removal ◽  
E Coli ◽  
Log Reduction ◽  
Ionic Compounds ◽  
Higher Doses

49 trials were carried out at pilot scale to evaluate ozonation for polishing a nitrified and filtered effluent discharged in a brook, lying in a recreational protected area whose low and irregular flow provides a negligible dilution. Four ozone doses (3, 5, 7.5 and 10 mg O3/L) were tested and contact time was set at 10 minutes for each of the three contact columns. In most cases, at 3 mg O3/L, residual ozone concentration was below detection limit after 10 minutes contact time. For faecal coliforms and E. coli, log reduction increased from 3 mg O3/L to higher ozone doses, among which no appreciable difference was observed. No improvement in disinfection efficiency was seen for contact times over 10 minutes. Complete disinfection was obtained only in few cases, but final counts complying with the limits for discharge were always met. COD removal was low, while colour removal was significant and clearly increasing from 3 mg O3/L to higher doses. The removal of surfactants slightly increased with increasing dose for non ionic compounds, but not for anionic ones. Data confirmed that slight increases in ozone dose involve the release of bacterial organic matter which partially counterbalance the removal of COD.

Efficacy of UV Light for the Reduction of Listeria monocytogenes in Goat's Milk

2005 ◽  
Vol 68 (10) ◽  
pp. 2212-2216 ◽  
Author(s):  
K. E. MATAK ◽  
J. J. CHUREY ◽  
R. W. WOROBO ◽  
S. S. SUMNER ◽  
E. HOVINGH ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Uv Light ◽  
Dose Range ◽  
Federal Regulations ◽  
Milk Products ◽  
Log Reduction ◽  
Goat’S Milk ◽  
Unpasteurized Milk ◽  
Goat's Milk ◽  
Uv Dose

Certain types of goat's cheeses are produced using unpasteurized milk, which increases the food safety concerns for these types of products. Popularity and consumption of goat's milk products have increased, and the niche market includes gourmet goat's cheeses. The U.S. Code of Federal Regulations and the Pasteurized Milk Ordinance both address the possibility for processing alternatives to heat treatment, and the use of UV light treatment may be a viable alternative that still ensures the safety of the product. Fresh goat's milk was inoculated with Listeria monocytogenes (L-2289) at 107 CFU/ml and exposed to UV light using the CiderSure 3500 apparatus (FPE Inc., Macedon, NY). Inoculated milk was exposed to a UV dose range between 0 and 20 mJ/cm2 to determine the optimal UV dose. A greater than 5-log reduction was achieved (P < 0.0001) when the milk received a cumulative UV dose of 15.8 ± 1.6 mJ/cm2. The results of this study indicate that UV irradiation could be used for the reduction of L. monocytogenes in goat's milk.

Experimental assessment of RSF, UF, RSF-O3 and RSF-H2O2/UV for unrestricted agricultural wastewater reuse in Italy

2013 ◽  
Vol 8 (1) ◽  
pp. 70-82
Author(s):  
C. Parabita ◽  
L. Guglielmi ◽  
L. Canovi ◽  
S. Sorlini ◽  
F. Gialdini ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Treatment Options ◽  
Wastewater Reuse ◽  
Complete Removal ◽  
Mineral Oil ◽  
Secondary Effluent ◽  
Total Coliforms ◽  
Log Reduction ◽  
Wastewater Quality ◽  
Uv Dose

In this paper, tertiary treatment processes aimed at achieving a wastewater quality suitable for reuse in agriculture in Italy have been investigated, with experimental results generated by means of pilot and bench scale tests. Studies were conducted to assess the removal of mineral oil, total surfactants, total coliforms, Escherichia coli and Salmonella using the following treatment options: rapid sand filtration (RSF), hollow fiber ultrafiltration (UF), RSF followed by ozonation (RSF-O3) and RSF followed by hydrogen peroxide combined with UV radiation (RSF-H2O2/UV). Mineral oil concentration, evaluated by means of the hydrocarbon oil index measurement, indicated an effluent concentration consistently below 0.05 mg/L for all processes studied. While total surfactants in the secondary effluent never exceeded the applicable limit of 0.5 mg/L during the studies, the degree of removal measured in studied treatments ranged from moderate to low, with the greatest removal observed using RSF-O3 (24%) and RSF-H2O2/UV (30%) under applied conditions. Overall, the optimal treatment performances were achieved by the RSF-H2O2/UV combined process using ≥1.5 mg/L H2O2 and UV dose ≥45 mJ/cm2, which provided adequate mineral oil and total surfactants removal, complete removal of measurable total suspended solids (TSS) and Salmonella, and greater than 4-log reduction in total coliforms and Escherichia coli.

Comparison of three laboratory devices for UV-inactivation of microorganisms

1995 ◽  
Vol 31 (5-6) ◽  
pp. 147-156 ◽  
Author(s):  
R. Sommer ◽  
A. Cabaj ◽  
D. Schoenen ◽  
J. Gebel ◽  
A. Kolch ◽  
...  
Keyword(s):  
Uv Irradiation ◽  
Uv Light ◽  
Collaborative Study ◽  
Test Organism ◽  
Dose Measurement ◽  
Technical Problems ◽  
Log Reduction ◽  
Freeze Dried ◽  
Test Organisms ◽  
Uv Dose

UV inactivation experiments of microorganisms have been performed and published by various workers for decades. Resulting data even of the same species of microorganisms may show important differences in UV-susceptibility. The reasons for these varying results could be found either in different biological conditions like culturing methods for preparing the test organisms or in technical problems regarding UV-irradiation equipment and dose measurement. Therefore three groups working on UV inactivation performed a collaborative study to find out which influences could be responsible for varying results in laboratory UV experiments. Each working group had developed a laboratory UV irradiation apparatus, which differed in technical construction and method for UV dose measurement. For our study we used as a test organism spores of Bacillus subtilis ATCC 6633 which were cultured in large quantity, freeze-dried and stored for all following experiments. Thereby we established controlled biological conditions. The first series of experiments in 1992 showed that differences in inactivation curves did occur, related especially to dose distribution in irradiation vessels, in irradiation geometry and in partial shadowing of UV light. Subsequently the irradiation procedure and methods for dose measurement were improved resulting in consistent, reproducible and comparable results. The equation of the regression curve was: log (N/N0) = −0.013 D + 0.18. A 2 log reduction would require a dose of 169 ± 11 J/m2, a 3 log reduction 241 ± 9 J/m2, respectively (level of significance: a = 0.05). In recent years bioassay methods have been suggested in order to evaluate UV-disinfection plants. Therefore it will be of increasing public health interest to ensure the quality of laboratory UV irradiation devices used for calibration of test-organisms for these bioassays.

Modeling of Escherichia coli Inactivation by UV Irradiation at Different pH Values in Apple Cider

2004 ◽  
Vol 67 (6) ◽  
pp. 1153-1156 ◽  
Author(s):  
A. QUINTERO-RAMOS ◽  
J. J. CHUREY ◽  
P. HARTMAN ◽  
J. BARNARD ◽  
R. W. WOROBO
Keyword(s):  
Escherichia Coli ◽  
Uv Irradiation ◽  
Uv Light ◽  
Reduction Factor ◽  
Attractive Alternative ◽  
Bacterial Populations ◽  
Apple Cider ◽  
E Coli ◽  
Log Reduction ◽  
Uv Dose

This study examined the effects and interactions of UV light dose (1,800 to 20,331 μJ/cm2) and apple cider pH (2.99 to 4.41) on the inactivation of Escherichia coli ATCC 25922, a surrogate for E. coli O157:H7. A predictive model was developed to relate the log reduction factor of E. coli ATCC 25922 to the UV dose. Bacterial populations for treated and untreated samples were enumerated with the use of nonselective media. The results revealed that UV dose was highly significant in the inactivation of E. coli, whereas pH showed no significant effect at higher UV doses. Doses of 6,500 μJ/cm2 or more were sufficient to achieve a greater than 5-log reduction of E. coli. Experimental inactivation data were fitted adequately by a logistic regression model. UV irradiation is an attractive alternative to conventional methods for reducing bacteria in unpasteurized apple cider.

scholarly journals Infectivity of Giardia duodenalis Cysts from UV Light-Disinfected Wastewater Effluent Using a Nude BALB/c Mouse Model

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Luciana Urbano dos Santos ◽  
Delma Pegolo Alves ◽  
Ana Maria Aparecida Guaraldo ◽  
Romeu Cantusio Neto ◽  
Mauricio Durigan ◽  
...  
Keyword(s):  
Uv Light ◽  
Sewage Treatment ◽  
Treatment Plant ◽  
Giardia Duodenalis ◽  
Average Concentration ◽  
Wastewater Effluent ◽  
Uv Disinfection ◽  
Disinfection Process ◽  
High Concentrations ◽  
The City

Giardia duodenalis is a protozoan of public health interest that causes gastroenteritis in humans and other animals. In the city of Campinas in southeast Brazil, giardiasis is endemic, and this pathogen is detected at high concentrations in wastewater effluents, which are potential reservoirs for transmission. The Samambaia wastewater treatment plant (WWTP) in the city of Campinas employs an activated sludge system for sewage treatment and ultraviolet (UV) light for disinfection of effluents. To evaluate this disinfection process with respect to inactivating G. duodenalis cysts, two sample types were investigated: (i) effluent without UV disinfection (EFL) and (ii) effluent with UV disinfection (EFL+UV). Nude immunodeficient BALB/c mice were intragastrically inoculated with a mean dose of 14 cysts of G. duodenalis recovered from effluent from this WWTP, EFL, or EFL+UV. All animals inoculated with G. duodenalis cysts developed the infection, but animals inoculated with UV-exposed cysts released a lower average concentration of cysts in their faeces than animals inoculated with cysts that were not UV disinfected. Trophozoites were also observed in both groups of animals. These findings suggest that G. duodenalis cysts exposed to UV light were damaged but were still able to cause infection.

scholarly journals Rotavirus Virus-Like Particles as Surrogates in Environmental Persistence and Inactivation Studies

2004 ◽  
Vol 70 (7) ◽  
pp. 3904-3909 ◽  
Author(s):  
Santiago Caballero ◽  
F. Xavier Abad ◽  
Fabienne Loisy ◽  
Françoise S. Le Guyader ◽  
Jean Cohen ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Uv Light ◽  
Expression System ◽  
Baculovirus Expression System ◽  
Virus Removal ◽  
Virus Like Particles ◽  
Reverse Transcription Pcr ◽  
Actual Field ◽  
Uv Dose ◽  
Green Fluorescent

ABSTRACT Virus-like particles (VLPs) with the full-length VP2 and VP6 rotavirus capsid proteins, produced in the baculovirus expression system, have been evaluated as surrogates of human rotavirus in different environmental scenarios. Green fluorescent protein-labeled VLPs (GFP-VLPs) and particles enclosing a heterologous RNA (pseudoviruses), whose stability may be monitored by flow cytometry and antigen capture reverse transcription-PCR, respectively, were used. After 1 month in seawater at 20°C, no significant differences were observed between the behaviors of GFP-VLPs and of infectious rotavirus, whereas pseudovirus particles showed a higher decay rate. In the presence of 1 mg of free chlorine (FC)/liter both tracers persisted longer in freshwater at 20°C than infectious viruses, whereas in the presence of 0.2 mg of FC/liter no differences were observed between tracers and infectious rotavirus at short contact times. However, from 30 min of contact with FC onward, the decay of infectious rotavirus was higher than that of recombinant particles. The predicted Ct value for a 90% reduction of GFP-VLPs or pseudoviruses induces a 99.99% inactivation of infectious rotavirus. Both tracers were more resistant to UV light irradiation than infectious rotavirus in fresh and marine water. The effect of UV exposure was more pronounced on pseudovirus than in GFP-VLPs. In all types of water, the UV dose to induce a 90% reduction of pseudovirus ensures a 99.99% inactivation of infectious rotavirus. Recombinant virus surrogates open new possibilities for the systematic validation of virus removal practices in actual field situations where pathogenic agents cannot be introduced.

scholarly journals 1146. Effectiveness of Ultraviolet Irradiation on Candida auris: A Laboratory Study

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S345-S345
Author(s):  
Gennifer Garmon ◽  
Dhammika Navarathna ◽  
John Coppin ◽  
Marjory Williams ◽  
Chetan Jinadatha
Keyword(s):  
Stainless Steel ◽  
Prolonged Exposure ◽  
Uv Light ◽  
Multidrug Resistant ◽  
Published Data ◽  
Log10 Reduction ◽  
Healthcare Associated Infection ◽  
Candida Auris ◽  
Light Emitting Devices ◽  
Log Reduction

Abstract Background Candida auris is a multidrug-resistant yeast which persists on healthcare surfaces for prolonged periods of time and is an emerging pathogen in hospitals. It has been linked to healthcare-associated infection (HAI) through surface transmission. Mobile ultraviolet (UV) light emitting devices from mercury sources have been shown to be effective in reducing C. auris bioburden but require prolonged exposure. In this study, we demonstrate the efficacy of an UV emitting device used in our hospital for terminal disinfection on C. auris. Methods Two C. auris strains (AR-381-CAU-01 and CAU-02) isolates obtained from Centers for Disease Prevention and Control (CDC) were used along with a Candida albicans (C. albicans) strain. An organism load of 10 μL containing 106 colony forming unit (CFU) was spread on a 20-mm diameter stainless steel coupon and exposed to the UV source from a pulsed xenon device at 5 feet distance and 4 feet height for 5, 10, and 30 minutes. Killing efficacy in terms of log reduction was calculated in comparison to untreated control coupons. Results Mean CFU log10 reduction for C. albicans, CAU-01, and CAU-02 was 0.547, 1.051, and 0.952 at 5 minutes; 1.412, 1.975, and 1.879 at 10 minutes; and 2.639, 3.971, and 4.145 at 30 minutes, respectively. Figure 1 describes the mean log10 reduction as well as the minimum and maximum log reduction by isolates. Conclusion Our study demonstrates the UV from a pulsed xenon device is effective in reducing the C. auris on stainless steel coupons. Similar to previously published data on reduction of C. auris by other UV sources, extended exposure is required to achieve a higher log reduction of C. auris. We did not have any C. auris clinical infections to assess efficacy of UV on HAI reduction. Disclosures C. Jinadatha, Xenex Healthcare Service: Grant Investigator, Research grant.

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