scholarly journals The Impact of Pipe Material on the Diversity of Microbial Communities in Drinking Water Distribution Systems

2021 ◽  
Vol 12 ◽  
Author(s):  
Debbie Lee ◽  
Gennaro Calendo ◽  
Kristin Kopec ◽  
Rebekah Henry ◽  
Scott Coutts ◽  
...  
Keyword(s):  
Drinking Water ◽  
Cast Iron ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Pipe Material ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
The Mean ◽  
The Impact

As many cities around the world face the prospect of replacing aging drinking water distribution systems (DWDS), water utilities must make careful decisions on new pipe material (e.g., cement-lined or PVC) for these systems. These decisions are informed by cost, physical integrity, and impact on microbiological and physicochemical water quality. Indeed, pipe material can impact the development of biofilm in DWDS that can harbor pathogens and impact drinking water quality. Annular reactors (ARs) with cast iron and cement coupons fed with chloraminated water from a municipal DWDS were used to investigate the impact of pipe material on biofilm development and composition over 16 months. The ARs were plumbed as closely as possible to the water main in the basement of an academic building to simulate distribution system conditions. Biofilm communities on coupons were characterized using 16S rRNA sequencing. In the cast iron reactors, β-proteobacteria, Actinobacteria, and α-proteobacteria were similarly relatively abundant (24.1, 22.5, and 22.4%, respectively) while in the cement reactors, α-proteobacteria and Actinobacteria were more relatively abundant (36.3 and 35.2%, respectively) compared to β-proteobacteria (12.8%). Mean alpha diversity (estimated with Shannon H and Faith’s Phylogenetic Difference indices) was greater in cast iron reactors (Shannon: 5.00 ± 0.41; Faith’s PD: 15.40 ± 2.88) than in cement reactors (Shannon: 4.16 ± 0.78; Faith’s PD: 13.00 ± 2.01). PCoA of Bray-Curtis dissimilarities indicated that communities in cast iron ARs, cement ARs, bulk distribution system water, and distribution system pipe biofilm were distinct. The mean relative abundance of Mycobacterium spp. was greater in the cement reactors (34.8 ± 18.6%) than in the cast iron reactors (21.7 ± 11.9%). In contrast, the mean relative abundance of Legionella spp. trended higher in biofilm from cast iron reactors (0.5 ± 0.7%) than biofilm in cement reactors (0.01 ± 0.01%). These results suggest that pipe material is associated with differences in the diversity, bacterial composition, and opportunistic pathogen prevalence in biofilm of DWDS.

The Laboratory Study of Drinking Water Biofilms

2014 ◽  
Vol 535 ◽  
pp. 455-459
Author(s):  
Jing Guo Zhao ◽  
Yu Long Yang ◽  
Cong Li
Keyword(s):  
Drinking Water ◽  
Water Temperature ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Future Research ◽  
Pipe Material ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Key Aspects

Due to the existence of some kinds of minim organic matters in drinking water distribution systems, biofilms are commonly found on the inner walls of pipe networks, and it can contribute to the deterioration to water quality and influence water supply security. The current situations of the study of the biofilm are summarized. Two typical kinds of reactors often used in laboratories are stated. And numerous environmental factors influencing biofilm formation, including hydraulic condition, water temperature, pipe material, water temperature, disinfectant residuals and nutrient element, are reviewed. Furthermore, some key aspects for future research to control the development of biofilms are proposed. Keywords: drinking water distribution system; biofilm; simulation system; disinfectant residual

Effect of chloramine residual on iron release in drinking water distribution systems

2009 ◽  
Vol 9 (4) ◽  
pp. 349-355 ◽  
Author(s):  
Y. Wang ◽  
X. J. Zhang ◽  
Z. B. Niu ◽  
C. Chen ◽  
P. P. Lu ◽  
...  
Keyword(s):  
Drinking Water ◽  
Cast Iron ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Iron Release ◽  
Residual Concentration ◽  
Drinking Water Distribution Systems ◽  
Chlorine Residual ◽  
Drinking Water Distribution

Iron release from scale brought about serious problems such as noticeable increases in turbidity and colour of the water in distribution system and taps. Field study and bench scale experiment on iron release from corrosion scale were carried out. In old cast iron pipe, higher iron release occurred with lower chlorine residual concentration, while lower iron release occurred with higher chlorine residual concentration. The reason lay in the structure of scale and the electro-chemical reactions occurring on the scale and in the bulk. The passivated-out-layer of scale was formed by ferric oxide. It could be broken down by reductive reaction in an atmosphere of low chlorine residual concentration. In contrast, the situation was quite different with new cast iron pipe, the age of which was only half a year. Iron release was considered as the product of the iron matrix and chlorine since the passivated-out-layer of scale had not formed yet. This iron release was consistent with chlorine residual concentration. It is suggested that maintaining a high chlorine residual concentration in a drinking water distribution system is beneficial to controlling both microorganism' regrowth and iron release.

Control of biofilm growth in drinking water distribution system by biodegradable carbon and disinfectant residuals

2006 ◽  
Vol 6 (2) ◽  
pp. 147-151 ◽  
Author(s):  
X.-J. Zhang ◽  
W. Lu
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Free Water ◽  
Planktonic Cell ◽  
Biofilm Growth ◽  
Bacteria Growth ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution

Biofilm growth in drinking water distribution systems was studied in an annular reactor system which was designed to model the hydraulic conditions in water mains. Experiments were performed with chlorine-free water as well as with different disinfectant (chlorine or chloramine) residuals and different AOC concentrations added to the reactor influent to examine the effect of disinfectant residuals and AOC concentrations on biofilm accumulation and planktonic cell numbers. The dynamic parameters of bacteria growth were calculated in water with different disinfectant (chlorine or chloramine) and the results indicated that monochloramine may be more effective than free chlorine for control of biofilm accumulation.

Prediction of chlorine and trihalomethanes concentration profile in bulk drinking water distribution systems from laboratory data

2003 ◽  
Vol 3 (1-2) ◽  
pp. 239-246 ◽  
Author(s):  
G. Kastl ◽  
I. Fisher ◽  
V. Jegatheesan ◽  
J. Chandy ◽  
K. Clarkson
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Laboratory Data ◽  
Water Distribution Systems ◽  
Optimum Level ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Chlorine Decay

Nearly all drinking water distribution systems experience a “natural” reduction of disinfection residuals. The most frequently used disinfectant is chlorine, which can decay due to reactions with organic and inorganic compounds in the water and by liquid/solids reaction with the biofilm, pipe walls and sediments. Usually levels of 0.2-0.5 mg/L of free chlorine are required at the point of consumption to maintain bacteriological safety. Higher concentrations are not desirable as they present the problems of taste and odour and increase formation of disinfection by-products. It is usually a considerable concern for the operators of drinking water distribution systems to manage chlorine residuals at the “optimum level”, considering all these issues. This paper describes how the chlorine profile in a drinking water distribution system can be modelled and optimised on the basis of readily and inexpensively available laboratory data. Methods are presented for deriving the laboratory data, fitting a chlorine decay model of bulk water to the data and applying the model, in conjunction with a simplified hydraulic model, to obtain the chlorine profile in a distribution system at steady flow conditions. Two case studies are used to demonstrate the utility of the technique. Melbourne’s Greenvale-Sydenham distribution system is unfiltered and uses chlorination as its only treatment. The chlorine model developed from laboratory data was applied to the whole system and the chlorine profile was shown to be accurately simulated. Biofilm was not found to critically affect chlorine decay. In the other case study, Sydney Water’s Nepean system was modelled from limited hydraulic data. Chlorine decay and trihalomethane (THM) formation in raw and treated water were measured in a laboratory, and a chlorine decay and THM model was derived on the basis of these data. Simulated chlorine and THM profiles agree well with the measured values available. Various applications of this modelling approach are also briefly discussed.

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