scholarly journals Disinfection by-products in drinking water distribution system of Bucharest City

2021 ◽  
Vol 3 (1) ◽  
pp. 10-18
Author(s):  
Iuliana Paun ◽  
◽  
Florentina Laura Chiriac ◽  
Vasile Ion Iancu ◽  
Florinela Pirvu ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Distribution System ◽  
Water Distribution ◽  
Inorganic Ions ◽  
Residual Chlorine ◽  
Chlorination Process ◽  
Water Legislation ◽  
Drinking Water Samples ◽  
By Products

Chlorine is widely used in Romania and all over the world as a disinfectant of drinking water. During the chlorination process, the natural organic matter and inorganic ions react with chlorine forming disinfection by-products (DBPs). The predominant organic disinfection by-products are trihalomethanes (THMs) while the main inorganic disinfection by-products are chlorate and chlorite ions. THMs were detected in all investigated drinking water samples from Bucharest distribution system with values from 27.8 µg/L up to 75.1 µg/L, which are below the maximum concentration value admitted by Romanian drinking water legislation of 100 µg/L. Chloroform constitutes the major component in total THMs concentration found in all tested drinking water. Chlorate and chlorite anions were not detected in any of the investigated drinking water samples. THMs concentration was correlated with total organic carbon (TOC), residual chlorine and chloride.

Phylogenetic assessment of heterotrophic bacteria from a water distribution system using 16S rDNA sequencing

2005 ◽  
Vol 51 (4) ◽  
pp. 325-335 ◽  
Author(s):  
Sima T Tokajian ◽  
Fuad A Hashwa ◽  
Ian C Hancock ◽  
Pierre A Zalloua
Keyword(s):  
Drinking Water ◽  
16S Rdna ◽  
Water Samples ◽  
Distribution System ◽  
Water Distribution ◽  
Heterotrophic Bacteria ◽  
Diagnostic Methods ◽  
Plate Count ◽  
Rdna Sequencing ◽  
Drinking Water Samples

Determination of a heterotrophic plate count (HPC) for drinking-water samples alone is not enough to assess possible health hazards associated with sudden changes in the bacterial count. Speciation is very crucial to determine whether the population includes pathogens and (or) opportunistic pathogens. Most of the isolates recovered from drinking water samples could not be allocated to a specific phylogenetic branch based on the use of conventional diagnostic methods. The present study had to use phylogenetic analysis, which was simplified by determining and using the first 500-bp sequence of the 16S rDNA, to successfully identify the type and species of bacteria found in the samples. Gram-positive bacteria α-, β-, and γ-Proteobacteria were found to be the major groups representing the heterotrophic bacteria in drinking water. The study also revealed that the presence of sphingomonads in drinking water supplies may be much more common than has been reported so far and thus further studies are merited. The intermittent mode of supply, mainly characterized by water stagnation and flow interruption associated possibly with biofilm detachment, raised the possibility that the studied bacterial populations in such systems represented organisms coming from 2 different niches, the biofilm and the water column.Key words: intermittent water supply, 16S rDNA, biofilm, water column.

Temporal variability of disinfection by-products concentration in urban public water system

2013 ◽  
Vol 14 (4) ◽  
pp. 393-398
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Temporal Variability ◽  
Water System ◽  
The Other ◽  
Major Constituent ◽  
System P ◽  
Public Water System ◽  
Drinking Water Samples ◽  
By Products

The occurrence of trihalomethanes (THMs) was studied in the drinking water samples from urban water supply network of Karachi city that served more than 18 million people. Drinking water samples were collected from 58 locations in summer (May-August) and winter (November-February) seasons. The major constituent of THMs detected was chloroform in winter (92.34%) and summer (93.07%), while the other THMs determined at lower concentrations. Summer and winter concentrations of total THMs at places exceed the levels regulated by UEPA (80 μg l-1) and WHO (100 μg l-1). GIS linked temporal variability in two seasons showed significantly higher median concentration (2.5%-23.06%) of THMs compared to winter.

Investigating disinfectant by-products in Harare potable water supply, Zimbabwe

2018 ◽  
Vol 8 (3) ◽  
pp. 415-428 ◽  
Author(s):  
Kuitakwashe Nhongo ◽  
Zvikomborero Hoko ◽  
Jameson Kugara
Keyword(s):  
Water Supply ◽  
Environmental Protection Agency ◽  
Distribution System ◽  
Water Distribution ◽  
The United States ◽  
World Health ◽  
Residual Chlorine ◽  
By Products ◽  
Trihalomethanes Formation

Abstract Formation of disinfectant by-products was investigated in the Harare water supply system from February to April 2015. Sampling sites were selected from the lake, Morton Jaffray Water Treatment Works and critical points in the distribution system. The spatial variations of trihalomethanes and selected water quality parameters were investigated for 15 sampling points in 5 sampling campaigns to assess suitability for drinking. All trihalomethane species were measured, namely chloroform, bromodichloromethane, dibromochloromethane and bromoform. Only chloroform and bromodichloromethane were detected. The study confirmed that there is trihalomethanes formation in the Harare water distribution system and that it is affected by the residence time and presence of organic matter in the system. However, the levels of trihalomethanes are generally within the levels suggested by the World Health Organization. Only bromodichloromethane presents a risk for long-term exposure as it had levels that exceeded the limit for long-term exposure suggested by the United States Environmental Protection Agency. Bromodichloromethane, turbidity and free residual chlorine levels were not suitable for drinking in some of the zones. Boosting of chlorine residuals is necessary especially in areas with free chlorine less than 0.2 mg/L. Injection of ammonia, periodic cleaning of storage reservoirs, and flushing of lines will reduce trihalomethanes formation.

Using monochloramines to disinfect drinking water: the effects it has on lead content

2010 ◽  
Vol 5 (2) ◽  
Author(s):  
A.M. Rizzuti ◽  
L.N. Rogers
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Distribution System ◽  
Water Distribution ◽  
Graphite Furnace ◽  
Atomic Absorption Spectrophotometry ◽  
The Past ◽  
Graphite Furnace Atomic Absorption ◽  
Water District ◽  
Pb Concentration

Over the past ten years, several U.S. cities have switched from using free chlorine to chloramines to disinfect drinking water. Coincident with this shift have been reports by some water districts of lead (Pb) levels in drinking water that exceed the action limit of 15ppb set by the EPA. In this paper, a study was conducted on a water district that utilizes monochloramines to disinfect drinking water. The purpose of this research was to determine the Pb content of drinking water treated in this district. Water samples were collected both from homes with and from homes without Pb plumbing. The water samples were analyzed for Pb content using graphite furnace atomic absorption spectrophotometry. Samples obtained from homes without Pb plumbing had a Pb concentration range of 10.7 ppb − 20.3 ppb (average = 15.9 ppb), whereas samples obtained from homes with Pb plumbing had a Pb concentration range of 20.4 ppb − 73.9 ppb (average = 29.0 ppb). The average Pb concentrations for both types of homes were above the EPA action limit of 15ppb. The most plausible explanation for this is leaching of Pb from the water distribution system caused by the water treatment plants' use of monochloramines to disinfect water.

Poor efficacy of residual chlorine disinfectant in drinking water to inactivate waterborne pathogens in distribution systems

1999 ◽  
Vol 45 (8) ◽  
pp. 709-715 ◽  
Author(s):  
Pierre Payment
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Clostridium Perfringens ◽  
Water Samples ◽  
Distribution System ◽  
Distribution Systems ◽  
Treatment Plant ◽  
Epidemiological Studies ◽  
Residual Chlorine ◽  
Residual Concentration

To evaluate the inactivating power of residual chlorine in a distribution system, test microorganisms (Escherichia coli, Clostridium perfringens, bacteriophage phi-X 170, and poliovirus type 1) were added to drinking water samples obtained from two water treatment plants and their distribution system. Except for Escherichia coli, microorganisms remained relatively unaffected in water from the distribution systems tested. When sewage was added to the water samples, indigenous thermotolerant coliforms were inactivated only when water was obtained from sites very close to the treatment plant and containing a high residual chlorine concentration. Clostridium perfringens was barely inactivated, suggesting that the most resistant pathogens such as Giardia lamblia, Cryptosporidium parvum, and human enteric viruses would not be inactivated. Our results suggest that the maintenance of a free residual concentration in a distribution system does not provide a significant inactivation of pathogens, could even mask events of contamination of the distribution, and thus would provide only a false sense of safety with little active protection of public health. Recent epidemiological studies that have suggested a significant waterborne level of endemic gastrointestinal illness could then be explained by undetected intrusions in the distribution system, intrusions resulting in the infection of a small number of individuals without eliciting an outbreak situation.Key words: drinking water, chlorine, disinfection, pathogens, distribution system.

scholarly journals Identification of Bacteria in Biofilm and Bulk Water Samples from a Nonchlorinated Model Drinking Water Distribution System: Detection of a Large Nitrite-Oxidizing Population Associated with Nitrospira spp

2005 ◽  
Vol 71 (12) ◽  
pp. 8611-8617 ◽  
Author(s):  
Adam C. Martiny ◽  
Hans-Jørgen Albrechtsen ◽  
Erik Arvin ◽  
Søren Molin
Keyword(s):  
Drinking Water ◽  
Organic Carbon ◽  
Water Samples ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Bulk Water ◽  
Drinking Water Distribution System ◽  
Assimilable Organic Carbon ◽  
Drinking Water Distribution

ABSTRACT In a model drinking water distribution system characterized by a low assimilable organic carbon content (<10 μg/liter) and no disinfection, the bacterial community was identified by a phylogenetic analysis of rRNA genes amplified from directly extracted DNA and colonies formed on R2A plates. Biofilms of defined periods of age (14 days to 3 years) and bulk water samples were investigated. Culturable bacteria were associated with Proteobacteria and Bacteriodetes, whereas independently of cultivation, bacteria from 12 phyla were detected in this system. These included Acidobacteria, Nitrospirae, Planctomycetes, and Verrucomicrobia, some of which have never been identified in drinking water previously. A cluster analysis of the population profiles from the individual samples divided biofilms and bulk water samples into separate clusters (P = 0.027). Bacteria associated with Nitrospira moscoviensis were found in all samples and encompassed 39% of the sequenced clones in the bulk water and 25% of the biofilm community. The close association with Nitrospira suggested that a large part of the population had an autotrophic metabolism using nitrite as an electron donor. To test this hypothesis, nitrite was added to biofilm and bulk water samples, and the utilization was monitored during 15 days. A first-order decrease in nitrite concentration was observed for all samples with a rate corresponding to 0.5 × 105 to 2 × 105 nitrifying cells/ml in the bulk water and 3 × 105 cells/cm2 on the pipe surface. The finding of an abundant nitrite-oxidizing microbial population suggests that nitrite is an important substrate in this system, potentially as a result of the low assimilable organic carbon concentration. This finding implies that microbial communities in water distribution systems may control against elevated nitrite concentrations but also contain large indigenous populations that are capable of assisting the depletion of disinfection agents like chloramines.

scholarly journals Prevalence of Legionella spp. and Escherichia coli in the drinking water distribution system of Wrocław (Poland)

2020 ◽  
Vol 20 (3) ◽  
pp. 1083-1090
Author(s):  
M. Wolf-Baca ◽  
A. Siedlecka
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Legionella Pneumophila ◽  
Water Samples ◽  
Distribution System ◽  
Water Distribution ◽  
Tap Water ◽  
Potential Threat ◽  
E Coli ◽  
Drinking Water Distribution

Abstract Drinking water should be free from bacterial pathogens that threaten human health. The most recognised waterborne opportunistic pathogens, dwelling in tap water, are Legionella pneumophila and Escherichia coli. Drinking water samples were tested for the presence of Legionella spp., L. pneumophila, and E. coli in overall sample microbiomes using a quantitative real-time polymerase chain reaction (qPCR) approach. The results indicate a rather low contribution of Legionella spp. in total bacteria in the tested samples, but L. pneumophila was not detected in any sample. E. coli was detected in only one sample, but at a very low level. The qacEΔ1 gene, conferring resistance to quaternary ammonium compounds, was also not detected in any sample. The results point to generally sufficient quality of drinking water, although the presence of Legionella spp. in tap water samples suggests proliferation of these bacteria in heating units, causing a potential threat to consumer health.

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