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1
Millership, S. E., and B. Chattopadhyay. "Aeromonas hydrophila in chlorinated water supplies." Journal of Hospital Infection 6, no. 1 (March 1985): 75–80. http://dx.doi.org/10.1016/s0195-6701(85)80021-9.
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2
LeChevallier, M. W., C. D. Cawthon, and R. G. Lee. "Factors promoting survival of bacteria in chlorinated water supplies." Applied and Environmental Microbiology 54, no. 3 (1988): 649–54. http://dx.doi.org/10.1128/aem.54.3.649-654.1988.
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3
Wyn-Jones, A. P., J. Watkins, C. Francis, M. Laverick, and J. Sellwood. "Enteric viruses in drinking water supplies." Water Supply 2, no. 3 (July 1, 2002): 17–22. http://dx.doi.org/10.2166/ws.2002.0080.
Повний текст джерелаАнотація:
Two rural spring drinking water supplies were studied for their enteric virus levels. In one, serving about 30 dwellings, the water was chlorinated before distribution; in the other, which served a dairy and six dwellings the water was not treated. Samples of treated (40 l) and untreated (20 l) water were taken under normal and heavy rainfall conditions over a six weeks period and concentrated by adsorption/elution and organic flocculation. Infectious enterovirus in concentrates was detected in liquid culture and enumerated by plaque assay, both in BGM cells, and concentrates were also analysed by RT-PCR. Viruses were found in both raw water supplies. Rural supplies need to be analysed for viruses as well as bacterial and protozoan pathogens if the full microbial hazard is to be determined.
4
Corso, Magali, Catherine Galey, René Seux, and Pascal Beaudeau. "An Assessment of Current and Past Concentrations of Trihalomethanes in Drinking Water throughout France." International Journal of Environmental Research and Public Health 15, no. 8 (August 6, 2018): 1669. http://dx.doi.org/10.3390/ijerph15081669.
Повний текст джерелаАнотація:
In France, 95% of people are supplied with chlorinated tap water. Due to the presence of natural organic matter that reacts with chlorine, the concentrations of chlorination by-products (CBPs) are much higher in chlorinated water produced from surface water than from groundwater. Surface water supplies 33% of the French population. Until the 1980s, almost all surface water utilities pre-chlorinated water at the intake. Pre-chlorination was then gradually banned from 1980 to 2000. Trihalomethanes (THMs) are the only regulated CBP in France. Since 2003, THMs have been monitored at the outlet of all utilities. This study assessed current (2005–2011) and past (1960–2000) exposure of the French population to THMs. We developed an original method to model THM concentrations between 1960 and 2000 according to current concentrations of THMs, concentration of total organic carbon in raw and finished water, and the evolution of water treatments from 1960 onward. Current and past mean exposure of the French population to THMs was estimated at 11.7 µg·L−1 and 17.3 µg·L−1, respectively. In the past, approximately 10% of the French population was exposed to concentrations >50 µg·L−1 vs. 1% currently. Large variations in exposure were observed among France’s 100 administrative districts, mainly depending on the water origin (i.e., surface vs. ground), ranging between 0.2 and 122.1 µg·L−1 versus between 1.8 and 38.6 µg·L−1 currently.
5
Nair, J., R. Gibbs, K. Mathew, and G. E. Ho. "Suitability of the H2S method for testing untreated and chlorinated water supplies." Water Science and Technology 44, no. 6 (September 1, 2001): 119–26. http://dx.doi.org/10.2166/wst.2001.0354.
Повний текст джерелаАнотація:
Rainwater, borewater and catchment water are used for domestic water supply purposes with or without treatment in remote areas around the world. These places seldom have any facilities for routine testing of their drinking water. A simple on-site testing method is highly required in such areas. The H2S method has been tested for treated drinking water and was found to have a good correlation with the standard methods. The present study was aimed at assessing the suitability of the H2S method for testing different sources of drinking water. Since these types of water may contain H2S producing bacteria not of faecal origin the occurrence of false results in this method cannot be overruled. Therefore it was worthwhile to study whether the positive results are true positive results and what percentage of false positive and false negative results could be expected while using this test for routine analysis of water samples. Results were compared with the results using standard procedures for testing total coliforms, Escherichia coli and Salmonella spp. The present experiment analysed 121 rainwater samples, 17 borewater samples, 41 catchment water samples and 74 remote Aboriginal community water samples. Rainwater, borewater and catchment water samples gave true results of 78.5%, 82.3% and 80.5% respectively while the treated and untreated community samples gave true results of 93.7 and 84.6% respectively. It was concluded that in the developing countries where the acceptable level of total coliform is <10 MPN, the H2S method would be a good test to identify microbial contamination. In other regions, the H2S method could be used as a screening test for drinking water supplies.
6
MacLeod, Clara, Rachel Peletz, Francis Kere, Aminata M’Baye, Michael Onyango, Sadat Aw, Mamadou El Hadj Issabre, Rosalind Tung, and Ranjiv Khush. "Are Presence/Absence Microbial Tests Appropriate for Monitoring Large Urban Water Supplies in Sub-Saharan Africa?" Water 11, no. 3 (March 8, 2019): 491. http://dx.doi.org/10.3390/w11030491.
Повний текст джерелаАнотація:
Screening for fecal contamination via microbial water quality monitoring is a critical component of safe drinking water provision and public health protection. Achieving adequate levels of microbial water quality testing, however, is a challenge in resource-limited settings. One strategy for addressing this challenge is to improve the efficiency of monitoring programs. In African countries, quantitative microbial testing methods are commonly used to monitor chlorinated piped water systems. However, presence/absence (P/A) tests may provide an appropriate alternative for water supplies that generally show negative fecal contamination results. This study compares 1048 water quality test results for samples collected from five African urban water systems. The operators of the systems conducted parallel tests on the 1048 samples using their standard quantitative methods (e.g., most probable number or membrane filtration) and the Colitag™ method in P/A format. Combined data demonstrates agreement rates of 97.9% (1024/1046) for detecting total coliforms and 97.8% (1025/1048) for detecting E. coli. We conclude that the P/A test offers advantages as a simpler and similarly sensitive measure of potential fecal contamination for large, urban chlorinated water systems. P/A tests may also offer a cost-effective alternative to quantitative methods, as they are quicker to perform and require less laboratory equipment.
7
LeChevallier, Mark W., Cheryl D. Cawthon, and Ramon G. Lee. "Mechanisms of Bacterial Survival in Chlorinated Drinking Water." Water Science and Technology 20, no. 11-12 (November 1, 1988): 145–51. http://dx.doi.org/10.2166/wst.1988.0277.
Повний текст джерелаАнотація:
Experiments showed that attachment of bacteria to surfaces provided the greatest increase in disinfection resistance. Attachment of high nutrient grown, unencapsulated, Klebsiellapneumoniae to glass microscope slides afforded the microorganisms as much as a 150 fold increase in disinfection resistance. Other mechanisms which increased disinfection resistance included: the age of the biofilm, bacterial encapsulation and previous growth conditions (e.g. growth medium, and growth temperature). These factors increased chlorine resistance from two to ten fold. The choice of disinfectant residual was shown to influence the type of resistance mechanism observed. Disinfection by free chlorine was affected by surfaces, age of the biofilm, encapsulation and nutrient effects. Disinfection by monochloramine, however, was only affected by surfaces. Importantly, the research showed that these resistance mechanisms were multiplicative (e.g. the resistance provided by one mechanism could be multiplied by the resistance provided by a second). These results provide important insights to understand the survival of bacteria in chlorinated drinking water supplies.
8
FURTADO, C., G. K. ADAK, J. M. STUART, P. G. WALL, H. S. EVANS, and D. P. CASEMORE. "Outbreaks of waterborne infectious intestinal disease in England and Wales, 1992–5." Epidemiology and Infection 121, no. 1 (August 1998): 109–19. http://dx.doi.org/10.1017/s0950268898001083.
Повний текст джерелаАнотація:
Following the introduction of an improved surveillance system for infectious intestinal disease outbreaks in England and Wales, the Public Health Laboratory Service Communicable Disease Surveillance Centre received reports of 26 outbreaks between 1 January 1992 and 31 December 1995 in which there was evidence for waterborne transmission of infection. In these 26 outbreaks, 1756 laboratory confirmed cases were identified of whom 69 (4%) were admitted to hospital. In 19 outbreaks, illness was associated with the consumption of drinking water from public supplies (10 outbreaks) or private supplies (9 outbreaks). The largest outbreak consisted of 575 cases. In 4 of the remaining 7 outbreaks, illness was associated with exposure to swimming pool water. Cryptosporidium was identified as the probable causative organism in all 14 outbreaks associated with public water supplies and swimming pools. Campylobacter was responsible for most outbreaks associated with private water supplies. This review confirms a continuing risk of cryptosporidiosis from chlorinated water supplies in England and Wales, and reinforces governmental advice to water utilities that water treatment processes should be rigorously applied to ensure effective particle removal. High standards of surveillance are important for prompt recognition of outbreaks and institution of control measures. As microbiological evidence of water contamination may be absent or insufficient to implicate a particular water supply, a high standard of epidemiological investigation is recommended in all outbreaks of suspected waterborne disease.
9
POLLOCK, K. G. J., D. YOUNG, C. ROBERTSON, S. AHMED, and C. N. RAMSAY. "Reduction in cryptosporidiosis associated with introduction of enhanced filtration of drinking water at Loch Katrine, Scotland." Epidemiology and Infection 142, no. 1 (April 16, 2013): 56–62. http://dx.doi.org/10.1017/s0950268813000678.
Повний текст джерелаАнотація:
SUMMARYPrevious evidence has suggested an association between cryptosporidiosis and consumption of unfiltered drinking water from Loch Katrine in Scotland. Before September 2007, the water was only micro-strained and chlorinated; however, since that time, coagulation and rapid gravity filtration have been installed. In order to determine risk factors associated with cryptosporidiosis, including drinking water, we analysed data on microbiologically confirmed cases of cryptosporidiosis from 2004 to 2010. We identified an association between the incidence of cryptosporidiosis and unfiltered Loch Katrine drinking water supplied to the home (odds ratio 1·86, 95% confidence interval 1·11–3·11, P = 0·019). However, while filtration appears to be associated with initially reduced rates of cryptosporidiosis, evidence suggests it may paradoxically make those consumers more susceptible to other transmission routes in the long-term. These findings support implementation of similar treatment for other unfiltered drinking-water supplies, as a means of reducing cryptosporidiosis associated with drinking water.
10
Donati, M., E. Cremonini, A. Di Francesco, L. Dallolio, R. Biondi, R. Muthusamy, and E. Leoni. "Prevalence of Simkania negevensis in chlorinated water from spa swimming pools and domestic supplies." Journal of Applied Microbiology 118, no. 4 (February 17, 2015): 1076–82. http://dx.doi.org/10.1111/jam.12761.
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11
Danylova, I. "Chloroform contamination of potable water as a result of its disinfection." Agroecological journal, no. 4 (December 17, 2016): 158–62. http://dx.doi.org/10.33730/2077-4893.4.2016.271287.
Повний текст джерелаАнотація:
Practically all water supplies of Ukraine use a chlorine or connections that contain chlorine for water treatment. In the process of water preparation organic substances that are included in its composition co-operate with disinfectants, and as a result a few types of trihalomethanes (ТHМ) appear, and chloroform prevails among them. Sufficiently long time the underestimation of the most meaningful sides of their biological action took place — remote consequences, in particular mutagenic and carcinogenic action. Although in experiments on higher animals, data about the chloroform cancerogenicity for organisms were got and after classification of IARC (France) it was attributed to the group 2 (factors that are probably carcinogenic for a human), the increase of morbidity from cancer among people who used the chlorinated drinking-water in epidemiology researches didn’t confirm clearly in the half of cases during observation. It was determined later that chlorinated drinking-water influences elasticity of blood vessels. They become harder, and that is why functioning of the cardiovascular system is violated. And, as known, the lost elasticity of blood vessels causes atherosclerosis, disease of heart. In opinion of several authors, risk of development of cancer for people and animals that use the chlorinated water, grows substantially. The presence of organic substances in water supplies causes chloroform formation in drinking water. Frequently «water-blooming», which is caused by growth of phytoplankton in consequence of coming of biogenic substances into the water, determines the appearance of organic compounds. Article writes above determining actuality of problem of danger of chloroform contamination of drinking-water for a human and animals as a result of its disinfection and bleaching with liquid chlorine during water treatment. Some indices of drinking water quality which influence the chloroform formation in it are analyzed. It is noted that oxygen concentration and turbidity here have to be examined as the most essential indices that testify the level of water contamination and determine the necessary terms of its bleaching and disinfestation. Reproduction intensity of diatomaceous, blue-green and green algae is investigated in the water intake «Vidsichne» of the Teteriv river in 2014 and it is shown that an active development of planktonic algae causes the necessity to increase the doses of reagents, that are added to water during its preparation. The features of different departments’ coexistence of phytoplankton in a water intake and their influence on the changes of turbidity indices and size of oxygen are also educed.
12
Kay, D., A. P. Wyn-Jones, C. M. Stapleton, L. Fewtrell, M. D. Wyer, J. Watkins, C. A. Francis, and D. Drury. "The microbiological quality of seven large commercial private water supplies in the United Kingdom." Journal of Water and Health 5, no. 4 (May 1, 2007): 523–38. http://dx.doi.org/10.2166/wh.2007.042.
Повний текст джерелаАнотація:
Some 1% of the UK population derives their potable water from 140,000 private water supplies (PWSs) regulated by Local Authorities. The overwhelming majority of these are very small domestic supplies serving a single property or a small number of properties. Treatment for such supplies is rudimentary or non-existent and their microbiological quality has been shown to be poor in every published study to date. Private water supplies serving commercial enterprises such as hotels, restaurants, food production premises and factories are more frequently treated and subject to closer regulation in the United Kingdom. As a result, it has been assumed that these larger commercial supplies are less likely to experience elevated faecal indicator and pathogen concentrations at the consumer tap which have been observed at small domestic supplies. This paper reports on intensive monitoring at seven commercial private water supplies (six of which were treated) spread throughout the UK serving hotels, holiday parks and food production enterprises. Daily sampling of ‘potable’ water, both at the consumer tap and using large volume filtration for Giardia and Cryptosporidium spp. was conducted over two six week periods in the spring and autumn of 2000. This allowed the effects of short term episodic peaks in faecal indicator and pathogen concentration to be quantified. All the supplies experienced intermittent pathogen presence and only one, a chlorinated deep borehole supply, fully complied with UK water quality regulations during both periods of sampling. Poor microbiological water quality typically followed periods of heavy rainfall. This suggests that the design and installation of such systems should be undertaken only after the likely range of raw water quality has been characterised, which requires a thorough understanding of the effects of flow and seasonality on raw water quality. There is no reason to suspect that the monitored sites are uncharacteristic of other commercial supplies and the results reinforce public health concerns related to domestic supplies. Furthermore, the pattern of contamination is highly episodic, commonly lasting only a few days. Thus, the relatively infrequent regulatory monitoring of such supplies would be unlikely to identify the poor water quality episodes and does not provide the data necessary for public health protection. Although some statistical relationship was found between faecal indicator organisms and the presence of pathogens, the use of FIOs in assessments of regulatory compliance may not always provide a reliable measure of public health risk, i.e. indicator absence does not preclude pathogen presence. The results of this study suggest that a risk assessment system similar to the WHO ‘Water Safety Planning’ approach might offer a more appropriate regulatory paradigm for private water supplies.
13
Wade, Mary Margaret, Tracey D. Biggs, Joseph M. Insalaco, Lisa K. Neuendorff, Vicky L. H. Bevilacqua, Amanda M. Schenning, Lisa M. Reilly, et al. "Evaluation of Handheld Assays for the Detection of Ricin and Staphylococcal Enterotoxin B in Disinfected Waters." International Journal of Microbiology 2011 (2011): 1–5. http://dx.doi.org/10.1155/2011/132627.
Повний текст джерелаАнотація:
Development of a rapid field test is needed capable of determining if field supplies of water are safe to drink by the warfighter during a military operation. The present study sought to assess the effectiveness of handheld assays (HHAs) in detecting ricin and Staphylococcal Enterotoxin B (SEB) in water. Performance of HHAs was evaluated in formulated tap water with and without chlorine, reverse osmosis water (RO) with chlorine, and RO with bromine. Each matrix was prepared, spiked with ricin or SEB at multiple concentrations, and then loaded onto HHAs. HHAs were allowed to develop and then read visually. Limits of detection (LOD) were determined for all HHAs in each water type. Both ricin and SEB were detected by HHAs in formulated tap water at or below the suggested health effect levels of 455 ng/mL and 4.55 ng/mL, respectively. However, in brominated or chlorinated waters, LODs for SEB increased to approximately 2,500 ng/mL. LODs for ricin increased in chlorinated water, but still remained below the suggested health effect level. In brominated water, the LOD for ricin increased to approximately 2,500 ng/mL. In conclusion, the HHAs tested were less effective at detecting ricin and SEB in disinfected water, as currently configured.
14
Zitko, V. "First Derivative UV Spectra of Surface Water as a Monitor of Chlorination in Drinking Water Treatment." Scientific World JOURNAL 1 (2001): 39–43. http://dx.doi.org/10.1100/tsw.2001.13.
Повний текст джерелаАнотація:
Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.
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Literáthy, P., and F. László. "Micropollutants in the Danube River Basin." Water Science and Technology 40, no. 10 (November 1, 1999): 17–26. http://dx.doi.org/10.2166/wst.1999.0497.
Повний текст джерелаАнотація:
Monitoring programmes in river basins usually include monitoring heavy metals and selected organic micropollutants in water and sediment. Several survey results revealed contamination of the water resources in the Danube river basin. Besides those chemicals, for which regulations already exist, there are other compound classes, e.g., aromatic sulfonates, complexing agents and breakdown products that have not been considered in the past due to the lack of data on their occurrence. Such chemicals may well be relevant to water pollution, to drinking water supplies, particularly those using surface water intakes, or bankside filtered water, because of their large production volumes, persistence and polarity, although information is limited on their effects. Harmonisation of micropollutant monitoring tools is a major goal of the international co-operation in the Danube river basin. Heavy metals, petroleum and selected chlorinated hydrocarbons are on the list of determinands. Development of analytical methods for screening and quantifying organic micropollutants resulted in: (a) information on naphthalene-sulfonates in the river water in the Hungarian Danube reach, and (b) application of fluorescence spectroscopy for screening polar and non-polar aromatic compounds. It has been concluded that the fluorescence technique and the AOX determination provide appropriate screening for both polar and non-polar aromatic compounds, and chlorinated hydrocarbons, respectively.
16
Lahti, K., and L. Hiisvirta. "Causes of waterborne outbreaks in community water systems in Finland: 1980-1992." Water Science and Technology 31, no. 5-6 (March 1, 1995): 33–36. http://dx.doi.org/10.2166/wst.1995.0552.
Повний текст джерелаАнотація:
Finland is known as a country with thousands of unpolluted lakes and pristine groundwaters. For this reason treatment processes applied in the drinking-water industry are quite simple. These kinds of water supplies, as well as private wells, are vulnerable for accidental pollution, leading to twenty-four reported waterborne epidemics outbreaks in Finland in 1980-1992. About 40 per cent of these outbreaks were due to contaminated water from community drinking-water supplies. The number of people affected in these outbreaks was around 7 700. Contaminated groundwater was a more common cause than surface water. The majority of Finnish groundwater supplies distribute water without any treatment or only with alkalization. In most outbreaks leakage and blockage of a sewage pipe in the vicinity of a groundwater well resulted in the contamination of drinking-water. The largest of these outbreaks affected some 5 000 people. The etiologic agents in these epidemics were most probably viruses; faecal indicator bacteria and enteric viruses were detected in water samples during the epidemics. Contamination of water distribution networks due to cross-connection caused two restricted epidemics. Inadequate disinfection of surface water was the reason for three outbreaks. Two of these were caused by the same water supply in subsequent years. The raw water source for this supply was of quite a high quality, for which reason the treatment consisted only of rapid sand filtration and chlorination. For fear of the chlorinated organic compounds formed during disinfection the amount of chlorine in water treatment was reduced to a level where disinfection was inadequate, and some hundred people became ill. The etiologic agent in these outbreaks remained unknown.
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Kozlicic, Abdulah, Abdulfetah Hadzic, and Hrvoje Bevanda. "Improvised Purification Methods for Obtaining Individual Drinking Water Supply Under War and Extreme Shortage Conditions." Prehospital and Disaster Medicine 9, S1 (June 1994): S25—S28. http://dx.doi.org/10.1017/s1049023x00041145.
Повний текст джерелаАнотація:
AbstractBackground:Supplying an adequate amount of drinking water to a population is a complex problem that becomes an extremely difficult task in war conditions. In this paper, several simple methods for obtaining individual supplies of drinking water by filtration of atmospheric water with common household items are reported.Methods:Samples of atmospheric water (rain and snow) were collected, filtered, and analyzed for bacteriological and chemical content. The ability of commonly available household materials (newspaper, filter paper, gauze, cotton, and white cotton cloth) to filter water from the environmental sources was compared.Results:According to chemical and biological analysis, the best results were obtained by filtering melted snow from the ground through white cotton cloth.Conclusions:Atmospheric water collected during war or in extreme shortage conditions can be purified with simple improvised filtering techniques and, if chlorinated, used as an emergency potable water source.
18
SLADE, PETER J., MOHAMMED A. FALAH, and AHMED M. R. AI-GHADY. "Isolation of Aeromonas hydrophila from Bottled Waters and Domestic Water Supplies in Saudi Arabia." Journal of Food Protection 49, no. 6 (June 1, 1986): 471–76. http://dx.doi.org/10.4315/0362-028x-49.6.471.
Повний текст джерелаАнотація:
A total of 139 replicate samples of water were tested for Aeromonas hydrophila and coliforms. These consisted of 95 replicates from bottled mineral water, 13 replicates from flower petal infusions and 31 samples of domestic municipality supplies. Of these, 59 (43%) were positive for A. hydrophila, 15 (11%) were positive for coliforms and 11 (8%) positive for both A. hydrophila and coliforms. Most of the isolates of A. hydrophila came from various batches of one brand of bottled mineral water, none of which contained coliforms. The organism was isolated more frequently from newer samples, particularly those bottled for 59 d or less. Samples of treated water from one municipality were free from coliforms and A. hydrophila. Chlorinated water from another town was free from coliforms, but some samples contained A. hydrophila. In unchlorinated water from a third municipal source, there was a high degree of correlation between incidence of A. hydrophila and presence of coliforms. A selective method, using media without antibiotics, for isolation of A. hydrophila was used. A novel medium for the presumptive identification of A. hydrophila, gelatin arginine dihydrolase (GAD) medium, was assessed, with confirmation of suspected isolates using the API 20E system. Of 109 isolates from two selective agars identified with the organism on API strips, 18 (16.5%) were falsely gelatinase negative in GAD medium, of which 9 (8.3%) also gave false-negative arginine dihydrolase reactions. Of those presumptively identified as A. hydrophila in GAD, 4/95 isolates (4.2% false-positives) were not confirmed.
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LEVINE, WILLIAM C., WILLIAM T. STEPHENSON, and GUNTHER F. CRAUN. "Waterborne Disease Outbreaks, 1986–1988." Journal of Food Protection 54, no. 1 (January 1, 1991): 71–78. http://dx.doi.org/10.4315/0362-028x-54.1.71.
Повний текст джерелаАнотація:
From 1986 to 1988, 24 states and Puerto Rico reported 50 outbreaks of illness due to water that people intended to drink, affecting 25,846 persons. The protozoal parasite Giardia lamblia was the agent most commonly implicated in outbreaks, as it has been for the last 10 years; many of these outbreaks were associated with ingestion of chlorinated but unfiltered surface water. Shigella sonnei was the most commonly implicated bacterial pathogen; in outbreaks caused by this pathogen, water supplies were found to be contaminated with human waste. Cryptosporidium contamination of a chlorinated, filtered public water supply caused the largest outbreak during this period, affecting an estimated 13,000 persons. A large multistate outbreak caused by commercially produced ice made from contaminated well water caused illness with Norwalk-like virus among an estimated 5,000 persons. The first reported outbreak of chronic diarrhea of unknown cause associated with drinking untreated well water occurred in 1987. Twenty-six outbreaks due to recreational water use were also reported, including outbreaks of Pseudomonas dermatitis, associated with the use of hot tubs or whirlpools, and swimming-associated shigellosis, giardiasis, and viral illness. Although the total number of reported water-related outbreaks has been declining in recent years, the few large outbreaks due to Cryptosporidium, Norwalk-like agent, S. sonnei, and G. lamblia caused more cases of illness in 1987 than have been reported to the Water-Related Disease Outbreak Surveillance System for any other year since CDC and the Environmental Protection Agency began tabulating these data in 1971.
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Ley, Arthur, Susanne Barr, Diane Fredenburgh, Michael Taylor та Nina Walker. "Use of 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside for the isolation of β-galactosidase-positive bacteria from municipal water supplies". Canadian Journal of Microbiology 39, № 9 (1 вересня 1993): 821–25. http://dx.doi.org/10.1139/m93-122.
Повний текст джерелаАнотація:
A new medium, mX-Gal, has been developed for the membrane filter enumeration of β-galactosidase-positive bacteria in municipal water supplies. mX-Gal medium contains the chromogenic β-galactosidase substrate 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal). All Aeromonas, Citrobacter, and Enterobacter strains isolated from raw water on mX-Gal medium were β-galactosidase positive. In contrast, only 10 to 20% of these strains produced a red colony with a metallic sheen on m-Endo agar LES medium. Of 674 chlorinated water samples analyzed for total coliforms on m-Endo agar LES medium and for β-galactosidase-positive bacteria on mX-Gal medium, 18 that were negative for coliforms on m-Endo agar LES showed β-galactosidase-positive bacteria on mX-Gal. Of a total of 50 β-galactosidase-positive bacteria isolated from these samples, 76% were identified as Aeromonas hydrophila.Key words: β-galactosidase, 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside, total coliforms, Aeromonas.
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Beretta, Giovanni Pietro, Monica Avanzini, Tomaso Marangoni, Marino Burini, Giacomo Schirò, Jacopo Terrenghi, and Gaetano Vacca. "Groundwater modeling of the withdrawal sustainability of Cannara artesian aquifer (Umbria, Italy)." Acque Sotterranee - Italian Journal of Groundwater 7, no. 3 (September 25, 2018): 47–60. http://dx.doi.org/10.7343/as-2018-333.
Повний текст джерелаАнотація:
The Cannara aquifer (Umbria, Italy) has been known for more than a century, and is one of the main drinking water supplies in the Umbria Region. In the beginning it was used for irrigation purposes, since this area was mainly agricultural up to the 1960s. The groundwater—exploited by Umbra Acque S.p.A. (a Company supplying drinking water)—is 150 m under ground level and is contained in a porous confined aquifer, which originally had artesian characteristics. Exploitation of 200–300 l/s with nine wells caused a reduction of piezometric level, maintaining the confined aquifer conditions, except for a very short period during which the aquifer was depressurised by drought, and for increase of emergency withdrawals replacing other water supplies (from springs) for drinking purposes. The occasional presence of iron and ammonium ions confirms the confinement of the groundwater and their hydrochemical facies in a redox environment, while in nearby areas and shallow aquifers anthropogenic contaminants (nitrates and chlorinated solvents) are reported. For the protection of this aquifer of strategic interest (the most important well field in Umbria), all hydrological and hydrochemical data available have been reviewed, and the aquifer recharge studied. Sustainable rates of withdrawal, and groundwater protection areas have been identified using a numerical flow model. Further action for monitoring groundwater of both shallow and artesian aquifers, together with well-revamping, have been proposed.
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Freitas dos Santos, Luisa M., and Andrew G. Livingston. "Mineralisation of 1,2-dibromoethane and other brominated aliphatics under aerobic conditions." Water Science and Technology 36, no. 10 (November 1, 1997): 17–25. http://dx.doi.org/10.2166/wst.1997.0350.
Повний текст джерелаАнотація:
1,2-dibromoethane (DBE) is a common environmental contaminant; it is potentially carcinogenic and has been detected in soil and groundwater supplies. Most of the biodegradation studies to date have been performed under anaerobic conditions or in the context of soil remediation, where the pollutant concentration was in the ppb range. The aim of this work was to find a bacterial culture (axenic or mixed) capable of complete aerobic mineralisation of concentrations of DBE up to 1 g L−1 under well controlled laboratory conditions. A mixed culture capable of degrading DBE as a sole source of carbon has been enriched. In order to verify biodegradation, formation of biodegradation products as well as the disappearance of DBE were measured. The ability of this culture to degrade other chlorinated and brominated compounds has also been tested. Successful degradation of bromoethane, bromoethanol and bromochloroethane was achieved.
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LeJeune, J. T., T. E. Besser, D. H. Rice, J. L. Berg, R. P. Stilborn, and D. D. Hancock. "Longitudinal Study of Fecal Shedding of Escherichia coli O157:H7 in Feedlot Cattle: Predominance and Persistence of Specific Clonal Types despite Massive Cattle Population Turnover." Applied and Environmental Microbiology 70, no. 1 (January 2004): 377–84. http://dx.doi.org/10.1128/aem.70.1.377-384.2004.
Повний текст джерелаАнотація:
ABSTRACT Identification of the sources and methods of transmission of Escherichia coli O157:H7 in feedlot cattle may facilitate the development of on-farm control measures for this important food-borne pathogen. The prevalence of E. coli O157:H7 in fecal samples of commercial feedlot cattle in 20 feedlot pens between April and September 2000 was determined throughout the finishing feeding period prior to slaughter. Using immunomagnetic separation, E. coli O157:H7 was isolated from 636 of 4,790 (13%) fecal samples in this study, with highest prevalence earliest in the feeding period. No differences were observed in the fecal or water trough sediment prevalence values of E. coli O157:H7 in 10 pens supplied with chlorinated drinking water supplies compared with nonchlorinated water pens. Pulsed-field gel electrophoresis of XbaI-digested bacterial DNA of the 230 isolates obtained from eight of the pens revealed 56 unique restriction endonuclease digestion patterns (REDPs), although nearly 60% of the isolates belonged to a group of four closely related genetic subtypes that were present in each of the pens and throughout the sampling period. The other REDPs were typically transiently detected, often in single pens and on single sample dates, and in many cases were also closely related to the four predominant REDPs. The persistence and predominance of a few REDPs observed over the entire feeding period on this livestock operation highlight the importance of the farm environment, and not necessarily the incoming cattle, as a potential source or reservoir of E. coli O157:H7 on farms.
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McFeters, G., M. Pickett, S. Broadaway, and B. Pyle. "Impact of chlorine injury on reaction kinetics of coliforms and E. coli in colisureTM and LTB." Water Science and Technology 35, no. 11-12 (June 1, 1997): 419–22. http://dx.doi.org/10.2166/wst.1997.0770.
Повний текст джерелаАнотація:
This study compared a chromogenic and fluorogenic substrate based medium, Colisure, with the conventional fermentation based medium, lauryl tryptose broth (LTB), for the recovery of chlorine-injured and non-injured coliforms and E. coli. Mixed natural populations of coliforms from sewage, with and without chlorine exposure, and untreated surface water samples were examined following a USEPA established procedure. Colisure and LTB were examined after 20, 24, 28 and 48h incubation and reactions verified. There were slight increases in positive reactions over time with unchlorinated samples, for which the two media gave similar kinetic patterns. The increases over time with chlorinated samples were much greater than with unchlorinated samples. LTB gave significantly lower total positive responses and had a more pronounced lag period than did Colisure. Total coliform bacteria from surface water samples gave somewhat different reactions with more of an increase with time. Colisure recovered comparable or higher numbers of total coliforms and E. coli in 20–28h than LTB after 48h. These results confirm that Colisure gives improved recovery of chlorine-injured total coliforms and E. coli under conditions simulating treated drinking and source water, resulting in a more realistic estimate of the actual population of indicator bacteria in public water supplies.
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Vargas, Ignacio T., Javiera M. Anguita, Pablo A. Pastén, and Gonzalo E. Pizarro. "Chlorine Reduction Kinetics and its Mass Balance in Copper Premise Plumbing Systems During Corrosion Events." Materials 12, no. 22 (November 8, 2019): 3676. http://dx.doi.org/10.3390/ma12223676.
Повний текст джерелаАнотація:
Hypochlorous acid has been reported as the main oxidant agent responsible for the corrosion of copper plumbing systems in chlorinated water supplies. However, there is little information about chlorine consumption kinetics in a combined system (i.e., with dissolved oxygen (DO) and free chlorine), as well as its complete mass balance within a copper pipe during stagnation. The results of our experiments using copper pipes filled with synthetic drinking water, with a moderate alkalinity (pH = 7.2; dissolved inorganic carbon = 80 mg as CaCO3 /L), and tested under chlorine concentrations from 0 to 8 mg/L, show that chlorine depletion is associated with pipe wall reactions (i.e., copper oxidation and scale formation processes). Free chlorine was depleted after 4 h of stagnation and its kinetic constant depend on the initial concentration, probably due to diffusion processes. Surface analysis including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and total reflection X-ray fluorescence (T-XRF) suggest chlorine precipitation, probably as CuCl. The obtained kinetics of chlorine and DO reduction would be critical for modeling and prediction of corrosion events of copper premise plumbing systems. In addition, our results indicate that the pipe’s surface reactions due to corrosion induces a loss of free chlorine in the bulk water, decreasing chlorine added for disinfection and the subsequent effect on water quality.
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Kermani, Farhad Riazi, Anca-Maria Tugulea, Joan Hnatiw, Vadoud H. Niri, and Janusz Pawliszyn. "Application of automated solid-phase microextraction to determine haloacetonitriles, haloketones, and chloropicrin in Canadian drinking water." Water Quality Research Journal 48, no. 1 (February 1, 2013): 85–98. http://dx.doi.org/10.2166/wqrjc.2013.012.
Повний текст джерелаАнотація:
An automated headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method was developed to monitor the occurrence of selected haloacetonitriles (HANs), haloketones (HKs), and chloropicrin (CP) in drinking water supplies. The method was rapid with analysis time of 30 min, including extraction and chromatographic run. Chemical ionization (CI) was used to increase the sensitivity of the method for the HKs. SPME fibers with seven different coatings including commercial polyacrylate (PA), carbowax/divinylbenzene (CW/DVB), polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and a novel custom-made polydimethylsiloxane/divinylbenzene-N-vinylpyrrolidone (PDMS/DVB-NVP) were evaluated. The DVB/CAR/PDMS fiber was found more suitable for the range of the analytes and the novel PDMS/DVB-NVP fiber more efficient for the brominated acetonitriles under the experimental conditions. Method detection limits (MDLs) for the chlorinated acetonitriles and CP varied between 2 and 40 ng/L and for the brominated acetonitriles and HKs between 100 and 180 ng/L. Relative standard deviations (RSD %) of measurements were 4–7%. The method was applied in parallel with a liquid–liquid extraction gas chromatography electron capture detection (LLE-GC-ECD) method (EPA Method 551.1) to the analysis of drinking water samples from eight Canadian water treatment and distribution systems. The results generated by the two methods showed good agreement.
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Grabow, W. O. K., P. Coubrough, C. Hilner, and B. W. Bateman. "Inactivation of Hepatitis A Virus, Other Enteric Viruses and Indicator Organisms in Water by Chlorination." Water Science and Technology 17, no. 4-5 (April 1, 1985): 657–64. http://dx.doi.org/10.2166/wst.1985.0168.
Повний текст джерелаАнотація:
Hepatitis A virus (HAV) and various indicator organisms were mixed together in autoclaved biofilter effluent and broth-enriched tap water, and the survival kinetics of individual organisms after the addition of chlorine were compared. Chlorine was present in the reaction mixtures predominantly in the form of combined residuals. HAV was enumerated by a most probable number dilution assay using PLC/PRF/5 liver cells for propagation of the virus and radioimmunoassay for its detection. In both reaction mixtures HAV survived longer than Escherichia coli, Streptococcus faecalisi, poliovirus type 2, coxsackievirus B5 and reovirus type 3, while it was less resistant than coliphage MS2, coliphage VI (except in tap water), the simian SA-11 rotavirus and Mycobacterium fortuitum. The survival data indicate that viruses (including coliphages) tend to be relatively more resistant to combined chlorine residuals than bacteria, while bacteria tend to be relatively more resistant to free chlorine residuals than viruses. Coliform bacteria may thus be fairly reliable indicators of the virological safety of waters disinfected by free chlorine residuals, but not of waters disinfected by combined chlorine residuals, as in the case of the chlorination of wastewater or the chloramination of drinking-water supplies. The relatively high resistance to combined chlorine residuals of HAV and SA-11 virus (which is closely related to human rotavirus) emphasizes the shortcomings of methods available for virological water analysis because they do not detect HAV and rotavirus. The results support views that the virological safety of all chlorinated waters can be reliably monitored by means of practical indicator systems consisting of appropriate combinations of determinands such as the standard plate count, coliform bacteria, coliphages, acid-fast bacteria and faecal streptococci.
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Fulthorpe, Roberta R., Steven N. Liss, and D. Grant Allen. "Characterization of bacteria isolated from a bleached kraft pulp mill wastewater treatment system." Canadian Journal of Microbiology 39, no. 1 (January 1, 1993): 13–24. http://dx.doi.org/10.1139/m93-003.
Повний текст джерелаАнотація:
Water samples from the wastewater treatment system of a bleach kraft mill and from the river that supplies the mill were plated on six different media and culturable isolates were screened for substrate utilization patterns, taxonomic characters, plasmid content, and resistance to ampicillin, streptomycin, kanamycin, tetracycline, naldixic acid, mercury, nickel, copper, cobalt, cadmium, and zinc. A cluster analysis of the substrate utilization profiles and taxonomic characters revealed that Pseudomonas, Acinetobacter, and Acidovorax spp. were common among the culturable isolates from the river, while Ancylobacter aquaticus, Klebsiella spp., and an unknown group of pleomorphic Gram-negative methylotrophs were common among the culturable isolates from the mill treatment system. Of isolates from the settling pond and aerated lagoon, 78 and 64% carried plasmids, while only 56% of isolates from the river carried plasmids. Plasmids were significantly associated with resistance to cadmium but not with any other resistance characters. Large numbers of plasmid-carrying A. aquaticus strains and pleomorphic methylotrophs accounted for high plasmid incidence levels in the mill treatment system, and the ability to dechlorinate simple aliphatic substrates was found in these two groups as well as in one Pseudomonas strain.Key words: pulp and paper, wastewater treatment, chlorinated organics, culturable heterotrophs, methylotrophs, plasmids.
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Ram, Neil M. "A review of the significance and formation of chlorinated N-organic compounds in water supplies including preliminary studies on the chlorination of alanine, tryptophan, tyrosine, cytosine, and syringic acid." Environment International 11, no. 5 (January 1985): 441–51. http://dx.doi.org/10.1016/0160-4120(85)90227-2.
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Schaffner, C., M. Ahel, and W. Giger. "Field Studies on the Behaviour of Organic Micropollutants During Infiltration of River Water to Ground Water." Water Science and Technology 19, no. 7 (July 1, 1987): 1195–96. http://dx.doi.org/10.2166/wst.1987.0010.
Повний текст джерелаАнотація:
The fate of organic micropollutants during ground water infiltration is of great interest since many water works use bank filtration as a first step in the treatment of river water for public water supplies. Field and laboratory studies are necessary to enhance our knowledge on the behaviour of organic chemicals during infiltration of river water to ground water. In an earlier study nonpolar volatile compounds (e.g. tetrachloroethylene, 1,4-dichlorobenzene and 1,3-dimethylbenzene) were investigated in natural river-ground water infiltration systems in Switzerland (Schwarzenbach et al., 1983). In this poster we report on recent work using one of these field sites and studying pentachlorophenol (PCP), nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO) and nitrilotriacetate (NTA), Preliminary results will also be reported for ethylenediaminetetraacetate (EDTA) and polycyclic aromatic hydrocarbons. The field site for our investigation was in the lower Glatt Valley, Switzerland where the Glatt River infiltrates into a quarternary fluvioglacial valley fill aquifer. The Glatt River is a small, rather heavily polluted perialpine river which receives effluents from ten mechanical-biological treatment plants of municipal waste water (Ahel et al., 1984). At the field site the average discharge of the river is approximately 8 m3/sec and permanent infiltration of the river through a saturated zone can be assumed. Observation wells allowed the sampling of freshly infiltrated water at various distances (2,5 - 14 m) from the river. During one year seventeen sample series were collected at approximately monthly intervals including samples from the river and from four ground water observation wells. Pentachlorophenol was determined by a method based on the procedure by Renberg and Lindstróm (1981), Detailed descriptions of the analytical methods for NP, NP1EO, NP2EO and NTA are given elsewhere (Ahel and Giger, 1985; Schaffner and Giger, 1984). The observed averages and ranges of concentrations are given in Table 1. It was concluded that NTA is eliminated rapidly during ground water infiltration. Starting from a range of 8 to 83 mg/m3 and an average of 27 mg/m3 in the river, after 7 m of infiltration only 0.5 mg/m3 are left corresponding to an elimination of 98%. Low temperatures in winter (4 – 6 °C) and reduced oxygen contents in summer had no effect on the efficient elimination of NTA, This result is highly important in addressing the question as to what extent NTA might reach bank filtrated waters from polluted rivers. The phenolic pollutants were eliminated according to the sequence: NP1EO ≈ NP2EO > NP > PCP. This is based on the decrease of the average concentrations over the first seven meters of infiltration. In particular, PCP turned out to be rather persistent in the ground water but not to such a degree as tetrachloroethylene and other chlorinated solvents which had been studied earlier.
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Tafesse, Nebiyou, Massimiliano Porcelli, Sirak Robele Gari, and Argaw Ambelu. "Prevalence and Trends of Drinking Water Disinfection Byproducts-Related Cancers in Addis Ababa, Ethiopia." Environmental Health Insights 16 (January 2022): 117863022211125. http://dx.doi.org/10.1177/11786302221112569.
Повний текст джерелаАнотація:
Background: Disinfection byproducts (DBPs) from chlorinated drinking water have been linked to an increased risk of cancer in the bladder, stomach, colon, and rectum. No studies showed the independent trends and prevalence of these cancers in Ethiopia. Therefore, this study aimed to determine the prevalence and trends of disinfection byproducts-related cancers in Addis Ababa, Ethiopia. Methods: Data were collected from the Addis Ababa Cancer Registry. Spatial data sets were produced and classified into households receiving chlorinated surface water and less chlorinated groundwater. The Cochran-Armitage trend test was used to evaluate whether there was a disinfection byproducts-related cancers (DBRCs) trend among communities receiving chlorinated water. Negative binomial regression was used to analyze the incidence rate. Results: A total of 11, 438 cancer cases were registered between 2012 and 2016, and DBRCs accounted for approximately 17%. The majority of the total cancer cases were female; 7,706 (67%). The prevalence of DBRCs was found to be higher in communities supplied with chlorinated water. From 2012 to 2016, the trend of colon cancer increased (β = 10.3, P value = .034); however, esophageal cancer decreased (β = −6.5, P value = .018). Approximately 56% of colorectal cancer patients and 53% of stomach cancer patients are known to be using chlorinated surface water for drinking regularly. In addition, approximately 57.1% and 54% of kidney and bladder cancer patients, respectively, used chlorinated surface water. Conclusion: The prevalence of DBRCs in this study was found to be high. The colon cancer trend increased substantially from 2012 to 2016. The prevalence of DBRCs was higher in communities supplied with chlorinated surface water. Similarly, the prevalence of DBRCs was higher among males than females. Further study is required to validate the association between DBRCs and water chlorination.
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TODD, E. C. D. "Foodborne and Waterborne Disease in Canada - 1981 Annual Summary." Journal of Food Protection 50, no. 11 (November 1, 1987): 982–91. http://dx.doi.org/10.4315/0362-028x-50.11.982.
Повний текст джерелаАнотація:
In 1981, a total of 647 incidents, comprising 505 outbreaks and 142 single cases, caused illnesses in 4,804 persons. There were 14.8% fewer incidents and 32.5% fewer cases than recorded for 1980. Salmonella, Staphylococcus aureus, Clostridium perfringens and Bacillus cereus were the main bacteriological agents to cause illness, but there were far fewer incidents of salmonellosis in 1981 (36) compared with 1980 (64). Etiologic agents Coxiella burnetii, Listeria monocytogenes and Taenia saginata were reported for the first time in these summaries. Animal agents: paralytic shellfish poison, scombroid poison and insects had also been documented in 1980 and previous years, but the plant agents were new - taro leaves and tablets made from Spirulina alga. The number of incidents caused by chemical agents (51), mainly extraneous matter, rancid compounds, metals and monosodium glutamate, were the same as for 1980. Some of the more unusual chemical poisonings were lead in herbal capsules, mercury in yogurt, ammonia in frog legs and laxative in a cake. Ten foodborne disease related deaths occurred mainly in infants infected by Listeria and in elderly patients with salmonellosis in a home for the aged. About 33% of incidents and 41% of cases were associated with meat and poultry. Mishandling of food took place mainly in foodservice establishments (33.1% of incidents, 62.4% of cases), homes (13.4% of incidents and 9.5% of cases) and food processing establishments (13.1% of incidents and 2.9% of cases). Food processing problems resulted mainly from chemical contamination, particularly extraneous matter. Most incidents occurred in Ontario (41.3%), British Columbia (19.6%) and Alberta (11.6%), but on a 100,000 population basis incidents were highest in British Columbia (4.6), Nova Scotia (4.4), Alberta (3.4) and Ontario (3.1). Narrative reports of seven previously unpublished foodborne disease problems are presented. Eight incidents of waterborne disease, caused by Giardia lamblia, Campylobacter, Salmonella, Pseudomonas aeruginosa and an undetermined agent, are double the number recorded for both 1980 and 1979. However, the number of cases was far fewer in 1981 (178) compared with those for the previous year (1,124). The largest outbreak (46 cases) was caused by Pseudomonas infecting the skin and ears of whirlpool bathers in a motel. All the other incidents were from contaminated water obtained on camping trips (3), from Giardia-in-fected municipal water supplies, two from abroad (3) and from non-chlorinated wells contaminated with Salmonella (1).
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Zhuang, Ping, and Spyros G. Pavlostathis. "Effect of chlorinated alkenes on the reductive dechlorination and methane production processes." Water Science and Technology 30, no. 7 (October 1, 1994): 85–94. http://dx.doi.org/10.2166/wst.1994.0315.
Повний текст джерелаАнотація:
Mixed, acetate-fed methanogenic cultures were used to assess the effect of increasing tetrachloroethylene (PCE), trichloroethylene (TCE) and cis-1,2-dichloroethylene (cDCE) concentrations on the reductive dechlorination and primary metabolism (methane production) processes. In addition, the effect of TCE on the rate and extent of the reductive dechlorination of PCE was investigated. All cultures were developed in serum bottles and incubation was carried out at 35°C in the dark. Soil samples from two sites contaminated with chlorinated solvents served as the inoculum for this study. All chlorinated alkenes used were supplied as saturated solutions in the culture media. The rate of PCE dechlorination increased with increasing PCE concentrations. Both TCE and cDCE showed an increase in the dechlorination rate up to a solvent threshold concentration followed by a decrease. In all cases, the methane production rate decreased as the chlorinated alkene concentrations increased. However, the effect of chlorinated alkenes was more pronounced on methane production rather than on the extent of dechlorination. The relative toxicity of the chlorinated alkenes tested in this study formed the following ascending series: PCE < TCE < < cDCE.
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Murray, Anna L., Emily Kumpel, Rachel Peletz, Ranjiv S. Khush, and Daniele S. Lantagne. "The effect of sodium thiosulfate dechlorination on fecal indicator bacteria enumeration: laboratory and field data." Journal of Water and Health 16, no. 1 (December 4, 2017): 70–77. http://dx.doi.org/10.2166/wh.2017.077.
Повний текст джерелаАнотація:
Abstract In microbiological water quality testing, sample dechlorination with sodium thiosulfate is recommended to ensure that results accurately reflect the water quality at sample collection. Nevertheless, monitoring institutions in low-resource settings do not always dechlorinate samples, and there is limited research describing how this practice impacts drinking water quality results. The effect of dechlorination on indicator bacteria counts was evaluated by spiking laboratory water with five Escherichia coli (E. coli) concentrations (104–108 CFU/100 mL), chlorinating at six doses (0–0.6 mg/L), holding samples with and without sodium thiosulfate for 5–7 hours, and enumerating E. coli by membrane filtration with m-lauryl sulfate media. Additionally, sub-Saharan African water suppliers enumerated thermotolerant coliform by membrane filtration in paired chlorinated water samples collected with and without sodium thiosulfate. Across all E. coli and chlorine doses in the laboratory, and all field tests, samples held without sodium thiosulfate had lower bacteria counts (p < 0.001). Additionally, chlorinated water supply samples held without sodium thiosulfate had an 87.5% false negative rate. Results indicate the importance of dechlorinating microbiological water quality samples, discarding data from chlorinated samples collected without dechlorination, and reinforcing dechlorination recommendations in resource-limited environments to improve water safety management.
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DeSILVA, M. B., S. SCHAFER, M. KENDALL SCOTT, B. ROBINSON, A. HILLS, G. L. BUSER, K. SALIS, et al. "Communitywide cryptosporidiosis outbreak associated with a surface water-supplied municipal water system – Baker City, Oregon, 2013." Epidemiology and Infection 144, no. 2 (August 12, 2015): 274–84. http://dx.doi.org/10.1017/s0950268815001831.
Повний текст джерелаАнотація:
SUMMARYCryptosporidium, a parasite known to cause large drinking and recreational water outbreaks, is tolerant of chlorine concentrations used for drinking water treatment. Human laboratory-based surveillance for enteric pathogens detected a cryptosporidiosis outbreak in Baker City, Oregon during July 2013 associated with municipal drinking water. Objectives of the investigation were to confirm the outbreak source and assess outbreak extent. The watershed was inspected and city water was tested for contamination. To determine the community attack rate, a standardized questionnaire was administered to randomly sampled households. Weighted attack rates and confidence intervals (CIs) were calculated. Water samples tested positive for Cryptosporidium species; a Cryptosporidium parvum subtype common in cattle was detected in human stool specimens. Cattle were observed grazing along watershed borders; cattle faeces were observed within watershed barriers. The city water treatment facility chlorinated, but did not filter, water. The community attack rate was 28·3% (95% CI 22·1–33·6), sickening an estimated 2780 persons. Watershed contamination by cattle probably caused this outbreak; water treatments effective against Cryptosporidium were not in place. This outbreak highlights vulnerability of drinking water systems to pathogen contamination and underscores the need for communities to invest in system improvements to maintain multiple barriers to drinking water contamination.
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Ribeiro, Maura Regina, Luiz Carlos de Abreu, and Gabriel Zorello Laporta. "Drinking water and rural schools in the Western Amazon: an environmental intervention study." PeerJ 6 (June 15, 2018): e4993. http://dx.doi.org/10.7717/peerj.4993.
Повний текст джерелаАнотація:
Background Although water and sanitation are considered human rights, worldwide approximately three of 10 people (2.1 billion) do not have access to safe drinking water. In 2016, 5.6 million students were enrolled in the 34% of Brazilian schools located in rural areas, but only 72% had a public water supply network. The objective was to evaluate effectiveness of environmental intervention for water treatment in rural schools of the Western Amazonia, and determine the efficacy of water treatment using a simplified chlorinator on potability standards for turbidity, fecal coliforms and Escherichia coli. Methods A simplified chlorinator was installed for treatment of potable water in 20 public schools in the rural area of Rio Branco municipality, Acre state, Brazil. Results Before the intervention, 20% (n = 4), 100% (n = 20) and 70% (n = 14) of schools had water that failed to meet potability standards for turbidity, fecal coliforms and E. coli, respectively. However, after intervention, 70% (p = 0.68), 75% (p < 0.001) and 100% (p < 0.001) of schools complied with potability standards. Discussion This intervention considerably improved schools’ water quality, thus decreasing children’s health vulnerability due to inadequate water. Ancillary activities including training, educational lectures, installation of equipment, supply of materials and supplies (65% calcium hypochlorite and reagents) were considered fundamental to achieving success full outcomes. Installation of a simplified chlorinator in rural schools of the Western Amazon is therefore proposed as a social technology aiming at social inclusion, as well as economic and environmental sustainability.
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Hirata, T., K. Tosa, K. Kawamura, J. Nakajima, M. Kaneko, and K. Taguchi. "Heterotrophic Bacteria in Chlorinated Drinking Water Distribution Systems: Detection and Identification." Water Science and Technology 27, no. 3-4 (February 1, 1993): 155–58. http://dx.doi.org/10.2166/wst.1993.0339.
Повний текст джерелаАнотація:
In order to determine bacterial quality of supplied water, researches on detection and identification of heterotrophic bacteria In distribution basin water and tap water were conducted In several drinking water supply systems In Japan, using pour plate technique with two agar media of SPG (Incubated at 36°C) and PGY (at 25°C). Bacterial colonies formed on SPC agar were randomly selected, purified and identified to genus. Results obtained from this study were as follow. The density of SPC bacteria ranged from 0 to 190 cfu/mL, although no colony was detected after 1-day Incubation in all of water samples tested. The density of PGY bacteria was higher than SPC and were In the range of 0 to 380 cfu/mL. Maximal values were found In first flow of water from taps In the early morning which contained lower residual chlorine. Prolonged incubation time resulted In Increased bacterial counts on both SPC and PGY plates. This tendency was more noticeable In samples collected from taps, particularly In first flow of water In the early morning. Dominant genera of the bacteria grown on SPG varied with different water supply systems and were Alcaligenes, Bacillus, Flavobacterlum, Methylobacterlum and Pseudomonas.
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Mohankumar, Sree Kalpana, Ramesh Kumar Govindarajan, and Mohanasundari Chokkalingam. "Leptospirosis Outbreak in a Hill Due to Water From an Unprotected Well, Keerakadu Village, Kollihills, Namakkal, Tamilnadu, India." Infection Control & Hospital Epidemiology 41, S1 (October 2020): s310. http://dx.doi.org/10.1017/ice.2020.899.
Повний текст джерелаАнотація:
Background: Annually, an estimated 1.03 million leptospirosis cases lead to 2.9 million disability adjusted life years. A cluster of fever cases was reported in Keerakadu village, Kollihills block in Namakkal district of Tamilnadu state, India, on April 28, 2017. We investigated to control the outbreak. Methods: We did a cross-sectional survey between April 29 and May 1. We defined a case of fever as any resident of Keerakadu village with fever for >2 days, with or without headache or myalgia, between April 15 and May 1, 2017. We conducted active surveillance. We reviewed medical records. We collected the line list from nearby health centers. We computed proportions to calculate the attack rate. We collected 11 serum samples and tested for dengue, scrub typhus, hepatitis A and leptospirosis by IgM ELISA method. We did a Widal slide agglutination test. We conducted an environmental survey to identify water sources. We performed a dengue larval survey. We collected 5 water samples: 1 from unprotected well, 1 from overhead tank and 3 from the houses of residents. We tested for fecal coliforms in the district public health laboratory. Results: The population of Keeradu village was 540. We identified 11 cases, for an attack rate of 2% (11 of 540). The hospitalization rate of cases was 81% (9 of 11). Median age was 45 years (range, 23–65). Of 11 samples, 3 were positive for leptospirosis; all were negative for dengue, scrub typhus, hepatitis A, and typhoid. The single water source for the whole village was an open, unprotected well. This well supplied water every day to the community, both for drinking purpose and domestic use. No breeding of dengue larva was observed. All the 5 water samples tested positive for fecal coliforms. Water was not chlorinated regularly. All patients were isolated and treated in the primary health center. Prophylactic antibiotics were given to the whole community. Conclusions: There was a leptospirosis outbreak in Keerakadu village, probably due to contaminated water from unprotected well. There were no cases after May 1, 2017. We recommended that the community chlorinate the water regularly and protect the well. We also recommend continued surveillance and a rodent survey.Funding: NoneDisclosures: None
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Patterson, W. J., D. V. Seal, E. Curran, T. M. Sinclair, and J. C. McLuckie. "Fatal nosocomial Legionnaires' disease: relevance of contamination of hospital water supply by temperature-dependent buoyancy-driven flow from spur pipes." Epidemiology and Infection 112, no. 3 (June 1994): 513–25. http://dx.doi.org/10.1017/s0950268800051219.
Повний текст джерелаАнотація:
SUMMARYThe investigation, epidemiology, and effectiveness of control procedures during an outbreak of Legionnaires' disease involving three immunosuppressed patients are described. The source of infection appeared to be a network of fire hydrant spurs connected directly to the incoming hospital mains water supply. Removal of these hydrants considerably reduced, but failed to eliminate, contamination of water storage facilities. As an emergency control procedure the incoming mains water was chlorinated continuously. Additional modifications to improve temperature regulation and reduce stagnation also failed to eliminate the legionellae.A perspex test-rig was constructed to model the pre-existing hospital water supply and storage system. This showed that through the hydraulic mechanism known as ‘temperature buoyancy’, contaminated water could be efficiently and quickly exchanged between a stagnant spur pipe and its mains supply. Contamination of hospital storage tanks from such sources has not previously been considered a risk factor for Legionnaires' disease. We recommend that hospital water storage tanks are supplied by a dedicated mains pipe without spurs.
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Wąsowski, Jacek, Dariusz Kowalski, Beata Kowalska, Marian Kwietniewski, and Małgorzata Zawilska. "Water Quality Changes in Cement-Lined Water Pipe Networks." Applied Sciences 9, no. 7 (March 30, 2019): 1348. http://dx.doi.org/10.3390/app9071348.
Повний текст джерелаАнотація:
This research focused on a model setup fed with underground water pumped into a water supply network. The scope of the research included a long- and a short-term stagnation of water in the setup and a water flow of 0.1 m/s. The water supplied into the system gradually lost its corrosive properties and developed calcium carbonate precipitation capability. These processes indicated that cement components migrate from the lining into the water. Apart from the primary components, the presence of the following trace elements was found: iron (399.6 ppb), magnesium (17.8 ppm), zinc (26.9 ppb), barium (22.6 ppb), boron (21.6 ppb), sodium (10.8 ppm), gallium (2.1 ppb). At early stages of the operation, recorded quantities were not significant. Leaching of the trace elements from cement increased after water was chlorinated. In turn, the highest percent increases were observed in the case of zinc (217%), boron (19%) and gallium (12%), whereas the increase for sodium, iron, barium and magnesium in water was insignificant (reaching a few percent). A repeated analysis of samples of stagnant water in the setup showed that most of trace elements were below the detectability level. Final concentrations of all elements identified in the water after its contact with internal cement mortar lining were much lower than the limit values set out for drinking water.
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Besser, Thomas E., Jeffrey T. LeJeune, Daniel H. Rice, Janice Berg, R. P. Stilborn, Katherine Kaya, Wonki Bae, and Dale D. Hancock. "Increasing Prevalence of Campylobacter jejuni in Feedlot Cattle through the Feeding Period." Applied and Environmental Microbiology 71, no. 10 (October 2005): 5752–58. http://dx.doi.org/10.1128/aem.71.10.5752-5758.2005.
Повний текст джерелаАнотація:
ABSTRACT The prevalence of Campylobacter jejuni in commercial feedlot cattle was monitored throughout the feeding period by repeated bacteriologic culture of feces. Fecal pats (n = 10) in 20 feedlot pens were sampled at 2-weeks interval beginning at entry into the feedlot and continuing until slaughter. The least-squares mean C. jejuni prevalence increased from 1.6% at the first sampling to 61.3% at the final sampling just prior to slaughter. Diverse C. jejuni pulsed-field gel electrophoresis macrorestriction profiles (MRP) were identified among the cattle isolates, but five prevalent MRP and minor variants accounted for >80% of all typed isolates. Chlorination of the water supplied to the water troughs of half of the pens did not affect C. jejuni prevalence in the cattle. Overall, the least-squares mean C. jejuni prevalences were 45.6 and 43.6% in chlorinated and nonchlorinated feedlot pens, respectively. The results of this study demonstrate apparent transmission of C. jejuni among feedlot cattle during the feeding period, unaffected by water chlorination, resulting in a high prevalence of C. jejuni excretion by cattle approaching slaughter.
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Evenden, Matthew. "Water Purity, Health, and Expertise: Debating Fluoridation in Vancouver during the 1950s." Canadian Journal of Health History 39, no. 2 (September 1, 2022): 311–39. http://dx.doi.org/10.3138/cjhh.2022-546-092021.
Повний текст джерелаАнотація:
Whether or not to fluoridate community water supplies challenged communities across North America and beyond in the mid-twentieth century. Proponents of fluoridation argued that this public health measure could prevent dental caries at little cost and should be embraced; critics objected to what they considered to be mass medication, and an unwelcome intrusion of the state and experts into matters of personal health. While many communities across Canada participated in this fraught question, and the contours of the debate from place to place shared many features, fluoridation was always a local issue, tied to the community water supply. In Vancouver, a wartime controversy over whether to chlorinate the water supply had shaken faith in expertise and the state. The fluoridation debate thus followed a wider public reckoning over water purity, health, authority, and expertise, and gave the many shared features of the national fluoridation debate a different quality. While fluoridation was embraced in many North American communities, or at least accepted, in Vancouver the foundations of the debate in the 1950s weakened support for this public health measure in defence of pure water and against the advice of experts.
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Eshcol, Jayasheel, Prasanta Mahapatra, and Sarita Keshapagu. "Is fecal contamination of drinking water after collection associated with household water handling and hygiene practices? A study of urban slum households in Hyderabad, India." Journal of Water and Health 7, no. 1 (October 1, 2008): 145–54. http://dx.doi.org/10.2166/wh.2009.094.
Повний текст джерелаАнотація:
Water-borne illness, primarily caused by fecal contamination of drinking water, is a major health burden in the state of Andhra Pradesh, India. Currently drinking water is treated at the reservoir level and supplied on alternate days, necessitating storage in households for up to 48 hrs. We hypothesized that fecal contamination occurs principally during storage due to poor water handling. In this study we tested for coliform bacteria in water samples collected at distribution points as household storage containers were filled, and then tested containers in the same households 24–36 hours after collection. We also conducted an observational survey to make an assessment of water handling and hygiene. Ninety-two percent (47/51) of samples tested at supply points were adequately chlorinated and bacterial contamination was found in two samples with no residual chlorine. Samples collected from household storage containers showed an increase in contamination in 18/50 houses (36%). Households with contaminated stored samples did not show significant differences in demographics, water handling, hygiene practices, or sanitation. Nevertheless, the dramatic increase in contamination after collection indicates that until an uninterrupted water supply is possible, the point at which the biggest health impact can be made is at the household level.
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Tokajian, S., and F. Hashwa. "Water quality problems associated with intermittent water supply." Water Science and Technology 47, no. 3 (February 1, 2003): 229–34. http://dx.doi.org/10.2166/wst.2003.0200.
Повний текст джерелаАнотація:
A controlled study was conducted in Lebanon over a period of 12 months to determine bacterial regrowth in a small network supplying the Beirut suburb of Naccache that had a population of about 3,000. The residential area, which is fed by gravity, is supplied twice a week with chlorinated water from two artesian wells of a confined aquifer. A significant correlation was detected between the turbidity and the levels of heterotrophic plate count bacteria (HPC) in the samples from the distribution network as well as from the artesian wells. However, a negative significant correlation was found between the temperature and the HPC count in the samples collected from the source. A statistically significant increase in counts, possibly due to regrowth, was repeatedly established between two sampling points lying on a straight distribution line but 1 km apart. Faecal coliforms were detected in the source water but none in the network except during a pipe breakage incident with confirmed Escherichia coli reaching 40 CFU/100 mL. However, coliforms such as Citrobacter freundii, Enterobacter agglomerans, E. cloacae and E. skazakii were repeatedly isolated from the network, mainly due to inadequate chlorination. A second controlled study was conducted to determine the effect of storage on the microbial quality of household storage tanks (500 L), which were of two main types - galvanized cast iron and black polyethylene. The mean bacterial count increased significantly after 7 d storage in both tank types. A significant difference was found in the mean HPC/mL between the winter and the summer. Highest counts were found April-June although the maximum temperature was reported later in the summer. A positive correlation was established between the HPC/mL and pH, temperature and storage time.
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Rittmann, B. E., R. Nerenberg, K. C. Lee, I. Najm, T. E. Gillogly, G. E. Lehman, and S. S. Adham. "Hydrogen-based hollow-fiber membrane biofilm reactor (MBfR) for removing oxidized contaminants." Water Supply 4, no. 1 (February 1, 2004): 127–33. http://dx.doi.org/10.2166/ws.2004.0015.
Повний текст джерелаАнотація:
Research with a laboratory prototype and at the pilot scale documents that the hydrogen-based hollow-fiber Membrane-Biofilm Reactor (MBfR) is technically and economically feasible for reduction of nitrate and perchlorate. In the MBfR, H2 gas diffuses through the wall of a composite membrane, and an autotrophic biofilm naturally develops on the outside of the membrane, where the bacteria's electron acceptor is an oxidized contaminant (e.g., NO3− or ClO4−) supplied from the water. The hydrogen pressure to the hollow fibers is a key control parameter that can be adjusted rapidly and easily. For denitrification, partial nitrate removal often is acceptable, and the hydrogen pressure can be low to minimize the costs of H2 supply and the concentration of H2 in the effluent. When perchlorate must be reduced, full nitrate removal is essential, since NO3−-N above about 0.2 mg/L slows perchlorate reduction. Perchlorate reduction is sensitive to the hydrogen pressure, which underscores the critical role of H2 pressure for controlling process performance. Given that H2-oxidizing microorganisms have the potential to reduce many oxidized contaminants, we hypothesize that and are beginning to test how well the MBfR reduces bromate, selenate, chlorinated solvents, and other oxidized contaminants.
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Norton, Cheryl D., and Mark W. LeChevallier. "A Pilot Study of Bacteriological Population Changes through Potable Water Treatment and Distribution." Applied and Environmental Microbiology 66, no. 1 (January 1, 2000): 268–76. http://dx.doi.org/10.1128/aem.66.1.268-276.2000.
Повний текст джерелаАнотація:
ABSTRACT This pilot study compares the compositions of bacterial biofilms in pipe networks supplied with water containing either high levels of biodegradable organic matter (BOM) or low levels of BOM (conventionally or biologically treated, respectively). The Microbial Identification System for fatty acid analysis was utilized in this study to identify a large number of organisms (>1,400) to determine population changes in both conventionally and biologically treated water and biofilms. Data generated during this study indicated that suspended bacteria have little impact on biofilms, and despite treatment (conventional or biological), suspended microbial populations were similar following disinfection. Prechlorination with free chlorine resulted not only in reduced plate count values but also in a dramatic shift in the composition of the bacterial population to predominately gram-positive bacteria. Chlorination of biologically treated water produced the same shifts toward gram-positive bacteria. Removal of assimilable organic carbon by the biologically active filters slowed the rate of biofilm accumulation, but biofilm levels were similar to those found in conventionally treated water within several weeks. Iron pipes stimulated the rate of biofilm development, and bacterial levels on disinfected iron pipes exceeded those for chlorinated polyvinyl chloride pipes. The study showed that the iron pipe surface dramatically influenced the composition, activity, and disinfection resistance of biofilm bacteria.
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Nagarajan, R., and R. Welker. "Precision Cleaning in a Production Environment with High-Pressure Water." Journal of the IEST 35, no. 4 (July 1, 1992): 34–44. http://dx.doi.org/10.17764/jiet.2.35.4.f0ggh273m26kv916.
Повний текст джерелаАнотація:
The increasing contamination control requirements for disk drives, and the prevailing mandate to climinate chlorinated solvents in cleaning applications have allowed high-pressure water spray to emerge as an effective and environmentally sound method for cleaning. Certain substrates, such as machined metals and alloys, can be cleaned using high-pressure water to state-of-the-art cleanliness levels. Following developmental investigations in the laboratory, two cleaners utilizing high-pressure (up to 3000 psig), high-flow (up to 50 gpm) water have been procured for use at suppliers of critical disk-drive components. Acceptance-runoff, certification, and production-run cleanliness data pertaining two the two high-pressure cleaners are presented here in terms of liquid-born particle counts on contaminants extracted from substrates ultrasonically, or by means of a low-pressure water spray. Results indicate that residual particulate contamination levels on high-pressure sprayed parts may be lower by more than two orders of magnitude compared with those obtained by more conventional cleaning methods. The cleaning efficiency increases significantly with particle size. The importance of nozzle manifold design and placement, for both cleaning and drying, is demonstrated quantitatively with examples of the deleterious consequences of not optimizing them. The underlying cleaning mechanism is explained briefly. Potential advantages and disadvantages associated with high-pressure water spray cleaning are fully discussed, and recommendations are offered for utilizing this technology most effectively.
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Douterelo, I., S. Husband, V. Loza, and J. Boxall. "Dynamics of Biofilm Regrowth in Drinking Water Distribution Systems." Applied and Environmental Microbiology 82, no. 14 (May 6, 2016): 4155–68. http://dx.doi.org/10.1128/aem.00109-16.
Повний текст джерелаАнотація:
ABSTRACTThe majority of biomass within water distribution systems is in the form of attached biofilm. This is known to be central to drinking water quality degradation following treatment, yet little understanding of the dynamics of these highly heterogeneous communities exists. This paper presents original information on such dynamics, with findings demonstrating patterns of material accumulation, seasonality, and influential factors. Rigorous flushing operations repeated over a 1-year period on an operational chlorinated system in the United Kingdom are presented here. Intensive monitoring and sampling were undertaken, including time-series turbidity and detailed microbial analysis using 16S rRNA Illumina MiSeq sequencing. The results show that bacterial dynamics were influenced by differences in the supplied water and by the material remaining attached to the pipe wall following flushing. Turbidity, metals, and phosphate were the main factors correlated with the distribution of bacteria in the samples. Coupled with the lack of inhibition of biofilm development due to residual chlorine, this suggests that limiting inorganic nutrients, rather than organic carbon, might be a viable component in treatment strategies to manage biofilms. The research also showed that repeat flushing exerted beneficial selective pressure, giving another reason for flushing being a viable advantageous biofilm management option. This work advances our understanding of microbiological processes in drinking water distribution systems and helps inform strategies to optimize asset performance.IMPORTANCEThis research provides novel information regarding the dynamics of biofilm formation in real drinking water distribution systems made of different materials. This new knowledge on microbiological process in water supply systems can be used to optimize the performance of the distribution network and to guarantee safe and good-quality drinking water to consumers.
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BEUCHAT, LARRY R., THOMAS E. WARD, and CHARLES A. PETTIGREW. "Comparison of Chlorine and a Prototype Produce Wash Product for Effectiveness in Killing Salmonella and Escherichia coli O157:H7 on Alfalfa Seeds." Journal of Food Protection 64, no. 2 (February 1, 2001): 152–58. http://dx.doi.org/10.4315/0362-028x-64.2.152.
Повний текст джерелаАнотація:
Outbreaks of Salmonella and Escherichia coli O157:H7 infections associated with alfalfa and other seed sprouts have occurred with increased frequency in recent years. This study was undertaken to determine the efficacy of a liquid prototype produce wash product (Fit), compared with water and chlorinated water, in killing Salmonella and E. coli O157:H7 inoculated onto alfalfa seeds. We investigated the efficacy of treatments as influenced by seeds from two different lots obtained from two seeds suppliers and by two methods of inoculation. The efficacy of treatments was influenced by differences in seed lots and amount of organic material in the inoculum. Significant (α = 0.05) reductions in Salmonella populations on seeds treated with 20,000 ppm of chlorine or Fit for 30 min ranged from 2.3 to 2.5 log10 CFU/g and 1.7 to 2.3 log10 CFU/g, respectively. Reductions (α = 0.05) in E. coli O157:H7 ranged from 2.0 to 2.1 log10 CFU/g and 1.7 to more than 5.4 log10 CFU/g of seeds treated, respectively, with 20,000 ppm of chlorine or Fit. Compared with treatment with 200 ppm of chlorine, treatment with either 20,000 ppm of chlorine or Fit resulted in significantly higher reductions in populations of Salmonella and E. coli O157:H7. None of the treatments eliminated these pathogens as evidenced by their detection on enrichment of treated seeds. Considering the human health and environmental hazards associated with the use of 20,000 ppm of chlorine, Fit provides an effective alternative to chlorine as a treatment to significantly reduce bacterial pathogens that have been associated with alfalfa seeds.
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Bian, Kaiqin, Chen Wang, Shuyu Jia, Peng Shi, Huaicheng Zhang, Lin Ye, Qing Zhou, and Aimin Li. "Spatial dynamics of bacterial community in chlorinated drinking water distribution systems supplied with two treatment plants: An integral study of free-living and particle-associated bacteria." Environment International 154 (September 2021): 106552. http://dx.doi.org/10.1016/j.envint.2021.106552.
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