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.

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.

Establishing minimum free chlorine residual concentration for microbial control in a municipal drinking water distribution system

2014 ◽  
Vol 9 (4) ◽  
pp. 491-501 ◽  
Author(s):  
Jennie L. Rand ◽  
Graham A. Gagnon ◽  
Alisha Knowles
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Heterotrophic Bacteria ◽  
Full Scale ◽  
Free Chlorine ◽  
Source Analysis ◽  
Plate Count ◽  
Similar Data ◽  
Residual Concentration ◽  
Chlorine Residual

Distribution system data from a Nova Scotia municipal drinking water supply was collected over four years, including free chlorine residual concentration, heterotrophic plate count (HPC) bacteria, and temperature. These data were analyzed for occurrences of HPC bacteria greater than 500 colony forming units (CFU)/mL. The municipality was interested in determining if secondary chlorination practices were sufficient in maintaining microbial health in their distribution system. Coliform data were non-detect (total coliforms and Escherichia coli) in the distribution system over this period and thus heterotrophic bacteria were used to assess microbial health. Results were compared to similar data collected from pilot-scale studies that had been carried out using the same municipal water as the source. Analysis showed that a similar trend was observed between pilot- and full-scale samples. Full-scale data analysis revealed that the minimum disinfection requirement of 0.2 mg/L did not consistently control occurrences of heterotrophic bacteria from being greater than 500 CFU/mL. By comparison, maintaining a concentration of 0.3 mg/L or above, particularly in warm-weather systems, maintained the number of heterotrophic bacteria at below 500 CFU/mL. Fortunately the majority of samples collected in the full-scale distribution system (>89%) had a free chlorine residual concentration of greater than 0.30 mg/L. While it is recognized that this system had 100% compliance for E. coli, the goal of this work will help utilities understand how to utilize microbial data to inform operational disinfection targets for their distribution system.

Molecular characterization of bacteria inhabiting a water distribution system simulator

2003 ◽  
Vol 47 (5) ◽  
pp. 149-154 ◽  
Author(s):  
J.W. Santo Domingo ◽  
M.C. Meckes ◽  
J.M. Simpson ◽  
B. Sloss ◽  
D.J. Reasoner
Keyword(s):  
16S Rdna ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Heterotrophic Bacteria ◽  
Feed Water ◽  
Ammonia Oxidizing Bacteria ◽  
16S Rdna Pcr ◽  
The Impact

The objective of this study was to monitor the impact of chlorination and chloramination treatments on heterotrophic bacteria (HB) and ammonia-oxidizing bacteria (AOB) inhabiting a water distribution system simulator. HB densities decreased while AOB densities increased when chloramine was added. AOB densities decreased below detection limits after the disinfection treatment was switched back to chlorination. The presence of AOB was confirmed using a group-specific 16S rDNA-PCR method. 16S rDNA sequence analysis showed that most bacterial isolates from feed water, discharge water, and biofilm samples were α-Proteobacteria or β-Proteobacteria. The latter bacterial groups were also numerically dominant among the sequences recovered from water and biofilm 16S rDNA clone libraries. The relative frequency of each culturable bacterial group was different for each sample examined. Denaturing gradient gel electrophoresis analysis of total community 16S rDNA genes showed notable differences between the microbial community structure of biofilm samples and feed water. The results of this study suggest that disinfection treatments could influence the type of bacterial community inhabiting water distribution systems.

scholarly journals A biochemical multi-species quality model of a drinking water distribution system for simulation and design

2013 ◽  
Vol 23 (3) ◽  
pp. 571-585 ◽  
Author(s):  
Krzysztof Arminski ◽  
Tomasz Zubowicz ◽  
Mietek A. Brdys
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Heterotrophic Bacteria ◽  
Ammonia Oxidizing Bacteria ◽  
Large Set ◽  
Monitoring And Control ◽  
Quality Model ◽  
Drinking Water Distribution

Abstract Drinking Water Distribution Systems (DWDSs) play a key role in sustainable development of modern society. They are classified as critical infrastructure systems. This imposes a large set of highly demanding requirements on the DWDS operation and requires dedicated algorithms for on-line monitoring and control to tackle related problems. Requirements on DWDS availability restrict the usability of the real plant in the design phase. Thus, a proper model is crucial. Within this paper a DWDS multi-species quality model for simulation and design is derived. The model is composed of multiple highly inter-connected modules which are introduced to represent chemical and biological species and (above all) their interactions. The chemical part includes the processes of chloramine decay with additional bromine catalysis and reaction with nitrogen compounds. The biological part consists of both heterotrophic and chemo-autotrophic bacteria species. The heterotrophic bacteria are assumed to consume assimilable organic carbon. Autotrophs are ammonia oxidizing bacteria and nitrite oxidizing bacteria species which are responsible for nitrification processes. Moreover, Disinfection By-Products (DBPs) are also considered. Two numerical examples illustrate the derived model’s behaviour in normal and disturbance operational states.

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.

Research of Effect on Water Quality of Combined Stainless Steel Plastic Pipe and PPR Pipe

2013 ◽  
Vol 864-867 ◽  
pp. 2108-2111
Author(s):  
Tao Wu ◽  
Zeng Zhang Wang
Keyword(s):  
Water Quality ◽  
Stainless Steel ◽  
Drinking Water ◽  
Water Distribution ◽  
Heterotrophic Bacteria ◽  
Plate Count ◽  
Plastic Pipe ◽  
Attached Bacteria ◽  
Drinking Water Distribution

Taking combined stainless steel plastic pipe and PPR pipe which was widely used in the secondary water supply system as research objects, we do a research of effect on water quality of these pipelines. These test indexes were divided into basic indexes and additional indexes. In addition, heterotrophic bacteria plate count was used to observe the attached bacteria on the inner wall of these two different pipes. The results showed that these two kinds of pipes are qualified for their hygienic safety as drinking water distribution equipments. The effects of pipe wall on water quality increased with the immersion time. Combined stainless steel plastic pipe is better than PPR pipe for less impact on water quality, less biofilm microbes attached, better stability, superior antibacterial effects. The combined stainless steel plastic pipe can give a better hygienic safety protection for drinking water.

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