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.

Spatial variation of loose deposit characteristics in a 40 km long operational drinking water distribution system

2019 ◽  
Vol 5 (10) ◽  
pp. 1689-1698
Author(s):  
Xu Ma ◽  
Guiwei Li ◽  
Ying Yu ◽  
Ruya Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Eastern China ◽  
Drinking Water Distribution Systems ◽  
System P ◽  
Loose Deposit ◽  
Drinking Water Distribution

Discoloration problems have occurred in drinking water distribution systems continuously for several years in a rural area of eastern China.

scholarly journals Effect of Phosphorus on Survival of Escherichia coli in Drinking Water Biofilms

2007 ◽  
Vol 73 (11) ◽  
pp. 3755-3758 ◽  
Author(s):  
Talis Juhna ◽  
Dagne Birzniece ◽  
Janis Rubulis
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Phosphorus Addition ◽  
Drinking Water Distribution Systems ◽  
E Coli ◽  
Drinking Water Distribution

ABSTRACT The effect of phosphorus addition on survival of Escherichia coli in an experimental drinking water distribution system was investigated. Higher phosphorus concentrations prolonged the survival of culturable E. coli in water and biofilms. Although phosphorus addition did not affect viable but not culturable (VBNC) E. coli in biofilms, these structures could act as a reservoir of VBNC forms of E. coli in drinking water distribution systems.

Review / SynthèseA review of drinking-water-associated endotoxin, including potential routes of human exposure

2002 ◽  
Vol 48 (7) ◽  
pp. 567-587 ◽  
Author(s):  
William B Anderson ◽  
Robin M Slawson ◽  
Colin I Mayfield
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Tap Water ◽  
Disinfection Byproducts ◽  
Potential Health ◽  
Biofilm Growth ◽  
Disinfection Byproduct ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution

In the past decade efforts have been made to reduce the formation of harmful disinfection byproducts during the treatment and distribution of drinking water. This has been accomplished in part by the introduction of processes that involve the deliberate encouragement of indigenous biofilm growth in filters. In a controlled environment, such as a filter, these biofilms remove compounds that would otherwise be available as disinfection byproduct precursors or support uncontrolled biological activity in distribution systems. In the absence of exposure to chlorinated water, most biofilm bacteria are gram negative and have an outer layer that contains endotoxin. To date, outbreaks of waterborne endotoxin-related illness attributable to contamination of water used in hemodialysis procedures have been only infrequently documented, and occurrences linked to ingestion or through dermal abrasions could not be located. However, a less obvious conduit, that of inhalation, has been described in association with aerosolized water droplets. This review summarizes documented drinking-water-associated incidents of endotoxin exposure attributable to hemodialysis and inhalation. Typical endotoxin levels in water and conditions under which substantial quantities can enter drinking water distribution systems are identified. It would appear that endotoxin originating in tap water can be inhaled but at present there is insufficient information available to quantify potential health risks.Key words: endotoxin, lipopolysaccharide, LPS, drinking water.

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

scholarly journals Dynamic Hydraulics in a Drinking Water Distribution System Influence Suspended Particles and Turbidity, But Not Microbiology

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 109
Author(s):  
Emmanuelle I. Prest ◽  
Peter G. Schaap ◽  
Michael D. Besmer ◽  
Frederik Hammes
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Age ◽  
Short Term ◽  
Drinking Water Distribution Systems ◽  
Hydraulic Conditions ◽  
Drinking Water Distribution ◽  
Particle Counts

Spatial and short-term temporal changes in water quality as a result of water age and fluctuating hydraulic conditions were investigated in a drinking water distribution system. Online measurements of total and intracellular adenosine tri-phosphate (ATP), total and intact cell concentrations measured with flow cytometry (FCM), turbidity, and particle counts were performed over five weeks at five subsequent locations of the distribution system. The high number of parallel FCM and ATP measurements revealed the combined effect of water age and final disinfection on spatial changes in microbiology in the system. The results underlined that regular daily dynamics in flow velocities are normal and inevitable in drinking water distribution systems, and significantly impact particle counts and turbidity. However, hydraulic conditions had no detectable impact on the concentration of suspended microbial cells. A weak correlation between flow velocity and ATP concentrations suggests incidental resuspension of particle-bound bacteria, presumably caused by either biofilm detachment or resuspension from sediment when flow velocities increase. The highly dynamic hydraulic conditions highlight the value of online monitoring tools for the meaningful description of short-term dynamics (day-scale) in drinking water distribution systems.

The occurrence of filamentous fungi in drinking water distribution systems

1982 ◽  
Vol 28 (6) ◽  
pp. 667-671 ◽  
Author(s):  
L. A. Nagy ◽  
B. H. Olson
Keyword(s):  
Drinking Water ◽  
Filamentous Fungi ◽  
Distribution System ◽  
Membrane Filtration ◽  
Distribution Systems ◽  
Water Distribution ◽  
Drinking Water Distribution Systems ◽  
Colony Forming Units ◽  
Drinking Water Distribution ◽  
Fungal Colony

The densities of filamentous fungal colonies, together with physicochemical and bacteriological parameters, were assessed in a chlorinated and unchlorinated drinking water distribution system at eight separate times over a period of 1 year. Filamentous fungal colonies were enumerated by membrane filtration on Czapek–Dox agar. The mean number of filamentous fungal colony-forming units per 100 mL of drinking water was 18 in the unchlorinated and 34 in the chlorinated system. The majority of filamentous fungi isolated were saprophytic Deuteromycotina. The four most frequently occurring genera were Penicillium, Sporocybe, Acremonium, and Paecilomyces. In the chlorinated system, only physicochemical parameters correlated with observed fungal frequencies, whereas in the unchlorinated system, none of the parameters exhibited significant correlations with fungal numbers.

scholarly journals Virus contamination from operation and maintenance events in small drinking water distribution systems

2011 ◽  
Vol 9 (4) ◽  
pp. 799-812 ◽  
Author(s):  
Elisabetta Lambertini ◽  
Susan K. Spencer ◽  
Burney A. Kieke ◽  
Frank J. Loge ◽  
Mark A. Borchardt
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Tap Water ◽  
Water Distribution Systems ◽  
Ultraviolet Disinfection ◽  
Drinking Water Distribution Systems ◽  
Virus Contamination ◽  
Drinking Water Distribution

We tested the association of common events in drinking water distribution systems with contamination of household tap water with human enteric viruses. Viruses were enumerated by qPCR in the tap water of 14 municipal systems that use non-disinfected groundwater. Ultraviolet disinfection was installed at all active wellheads to reduce virus contributions from groundwater to the distribution systems. As no residual disinfectant was added to the water, any increase in virus levels measured downstream at household taps would be indicative of distribution system intrusions. Utility operators reported events through written questionnaires. Virus outcome measures were related to distribution system events using binomial and gamma regression. Virus concentrations were elevated in the wells, reduced or eliminated by ultraviolet disinfection, and elevated again in distribution systems, showing that viruses were, indeed, directly entering the systems. Pipe installation was significantly associated with higher virus levels, whereas hydrant flushing was significantly associated with lower virus levels. Weak positive associations were observed for water tower maintenance, valve exercising, and cutting open a water main. Coliform bacteria detections from routine monitoring were not associated with viruses. Understanding when distribution systems are most vulnerable to virus contamination, and taking precautionary measures, will ensure delivery of safe drinking water.

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.

scholarly journals Prevalence of bacterial pathogens in biofilms of drinking water distribution systems

2007 ◽  
Vol 5 (2) ◽  
pp. 219-227 ◽  
Author(s):  
S. M. September ◽  
F. A. Els ◽  
S. N. Venter ◽  
V. S. Brözel
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Most Probable Number ◽  
Human Consumption ◽  
Probable Number ◽  
Drinking Water Distribution Systems ◽  
Colony Forming Units ◽  
Drinking Water Distribution

Water for human consumption is required to be free from any bacteria that might pose a health risk. The presence of biofilms in the drinking water distribution system may play a role in the presence of potential pathogens in the drinking water supply. Ninety-five biofilm samples from various parts of South Africa were tested for the presence of Escherichia coli, Aeromonas, Pseudomonas, Salmonella, Shigella and Vibrio spp. Members of these genera were quantified by the three-tube most probable number (MPN) approach using enrichment broths and plating on selective agars. The heterotrophic culturable counts were determined for both the planktonic and biofilm phases of the samples. Biofilm density varied between 10 and 1.9 × 109 colony forming units cm−2. The 16S rRNA identity of the putative pathogenic isolates revealed that high numbers of Aeromonas, Pseudomonas,Klebsiella and Enterobacter were present, but no putative Salmonella and Shigella could be confirmed. None of the Pseudomonas isolates belonged to the pathogenic Pseudomonas aeruginosa or Pseudomonas mendocina while the Aeromonas isolates showed relatedness to known pathogenic members of this group.

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