Modelling biofilm growth and disinfectant decay in drinking water

2000 ◽  
Vol 41 (4-5) ◽  
pp. 339-345 ◽  
Author(s):  
V. Jegatheesan ◽  
G. Kastl ◽  
I. Fisher ◽  
M. Angles ◽  
J. Chandy
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Management Strategies ◽  
Bulk Water ◽  
System Management ◽  
Biofilm Growth ◽  
Biofilm Model ◽  
Biofilm Bacteria ◽  
Surface Detachment ◽  
Developing System

A simple biofilm model was developed to describe the growth of bacteria in drinking water biofilms and the subsequent interactions with disinfectant residuals incorporating the important processes, such as attachment of free bacteria to the biofilm on a wall surface, detachment of bacteria from the biofilm, growth of biofilm bacteria with chloramine inhibition, chloramine decay in the bulk water phase, and chloramine decay due to biofilm bacteria and wall surfaces. The model is useful in evaluating the biological stability of different waters, as it can predict concentration of organic substances in water. In addition, the model can be used to predict the bacterial growth and biofilm decay in distribution systems. A model of this kind is a useful tool in developing system management strategies to ultimately improve drinking water quality.

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.

Chlorine sensitivity of environmental, distribution system and biofilm coliforms

1997 ◽  
Vol 35 (11-12) ◽  
pp. 289-292 ◽  
Author(s):  
D. P. Sartory ◽  
P. Holmes
Keyword(s):  
Drinking Water ◽  
River Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Bulk Water ◽  
Coliform Bacteria ◽  
Environmental Distribution ◽  
River Waters ◽  
E Coli ◽  
Treated Drinking Water

Coliform bacteria, isolated from treated drinking water supplies, can be derived from a range of sources (e.g. infiltration, breakthrough at the treatment works or from the biofilm established within the pipework). The sensitivity of these bacteria to chlorine may be related to their source and metabolic status. Strains of coliforms were isolated from sewage works effluents, river and reservoir waters as well as from the bulk water and biofilms from distribution systems. These were assayed for sensitivity to free and total chlorine using two assay procedures. For E. coli, the isolates from the distribution system bulk water showed greater resistance to free chlorine than those from sewage effluents and equivalence to those from river waters. For non-E. coli coliforms (mainly strains of Klebsiella, Enterobacter and Citrobacter), those from distribution system biofilms showed the greatest sensitivity to free and total chlorine whilst those from river water had the greatest resistance.

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.

Contamination potential of biofilms in water distribution systems

2002 ◽  
Vol 2 (1) ◽  
pp. 271-280 ◽  
Author(s):  
H.-C. Flemming ◽  
S.L. Percival ◽  
J.T. Walker
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Synthetic Polymers ◽  
Water Phase ◽  
Limiting Factor ◽  
Biofilm Growth ◽  
Black Water ◽  
Large Numbers ◽  
Surface Covering

Biofilms are ubiquitous in drinking water systems, either in the form of thin and patchy colonies or as surface-covering multiple layers. In biofilters they are used for the elimination of biologically degradable substances. However, they occur in other sites, e.g., on the walls of containers and pipes, on sediment and on suspended particles. They can rise problems by contamination of the water phase by detaching biofilm organisms. Biofilms provide a possible habitat for hygienically relevant microbes in which they can persist and even multiply. Here they are protected against disinfectants, in particular if located in corrosion products, sediments or ingested by protozoa which feed on biofilm cells. Biofilms are related to the occurrence of “black water” and malodours. They are involved in the corrosion of metals, mineral materials and synthetic polymers. The limiting factor for biofilm growth is usually the availability of nutrients, mainly provided either by biodegradable substances leaching from materials or from by the water phase. The extent of biofilm growth and of the occurrence of hygienically relevant organisms is still unknown and to be investigated. However, latest research indicates that such organisms do not multiply in large numbers in drinking water biofilms; it is possible that drinking water biofilms can inhibit the propagation of invading pathogens.

Drinking Water Biofilm Management and Monitoring

2020 ◽  
Author(s):  
Frances Pick ◽  
Katherine Fish ◽  
Stewart Husband ◽  
Joby Boxall
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Asset Management ◽  
Distribution System ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Intact Cell ◽  
Line Pipe ◽  
Biofilm Growth ◽  
The Impact

<p>Biofilms within drinking water distribution systems can pose risks to consumers, especially when mobilised, as high concentrations of microorganisms and associated material can be released leading to degradation of water quality. Access and sampling of biofilms within drinking water pipelines can be difficult without disrupting supply in these extensive and buried systems. A novel biofilm monitoring device was developed to determine if biofilm formation rates can be used to assess microbiological water quality, track fouling rates and ultimately indicate distribution system performance. The device comprises a sample-line pipe with multiple, independent removable sections (allowing for biofilm sampling) that can be easily connected to sampling points in the distribution system. Biofilm is removed from the device and flow cytometry used to determine total and intact cell concentrations. The biomonitoring device was tested in a series of laboratory trials, to establish the impact of different flow rates and orientations on biofilm formation and to determine the optimum configuration that achieves accurate and repeatable results. Subsequently, these devices were installed in two operational systems, with different water qualities, and biofilms were sampled for two months to obtain biofilm growth rates. The results provide the first direct evidence of different biofilm formation rates in distribution systems with different water qualities. This evidence is now being used to investigate fouling rates via risk analysis and modelling. The use of the device has potential to improve understanding of biofilm behaviour and help inform biofilm and asset management to safeguard the quality of delivered drinking water.</p>

Biocorrosion in drinking water pipes

2016 ◽  
Vol 16 (4) ◽  
pp. 881-887 ◽  
Author(s):  
Gonzalo E. Pizarro ◽  
Ignacio T. Vargas
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Low Cost ◽  
Bulk Water ◽  
Transition Flow ◽  
Actual System ◽  
Drinking Water Distribution Systems ◽  
Copper Release

Copper is widely used in drinking water distribution systems due to its relatively low cost and favorable mechanical properties. However, copper corrosion may generate copper concentrations exceeding the thresholds prescribed by international drinking water standards. In-situ measurements performed in an actual system found that the copper mass released under flowing water conditions (pipe flushing) was greater than the copper mass release estimated considering only the mass of copper in the pipe's bulk water before the tap is opened. This work presents in-situ and laboratory results of copper release into the water and its dependence on biofilm structure, solid-liquid interface properties, and the pipe flow regime (laminar vs. transition flow). The results of this work highlight the necessity to incorporate the hydrodynamic effects in the analysis of corrosion and corrosion by-products release into drinking water piping systems. Initial modeling efforts are also presented.

Prevention of bacterial growth in drinking water distribution systems

1997 ◽  
Vol 35 (11-12) ◽  
pp. 283-287 ◽  
Author(s):  
Ph. Piriou ◽  
S. Dukan ◽  
Y. Levi ◽  
P. A. Jarrige
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Bacterial Growth ◽  
Distribution Systems ◽  
Water Distribution ◽  
Bacterial Count ◽  
Bulk Water ◽  
Drinking Water Distribution Systems ◽  
Biological Phenomena ◽  
Using Data

Of the many causes of drinking water quality deterioration in distribution systems, biological phenomena are undoubtedly the subject of the most study. They are also the most closely monitored because of short-term public health risks. A determinist model was developed to predict bacterial growth in the network and to locate the zones where the risks of biological proliferation are the highest. The model takes into account the growth of suspended and fixed bacteria, the consumption of available nutrients in the bulk water and in the biofilm layer, the influence of chlorine residual on the mortality of suspended and fixed biomass, the deposition of suspended bacteria and the detachment of biofilm cells, the influence of temperature on bacterial activity and chlorine decay. The model is constructed using hydraulic results previously generated by PICCOLO, the SAFEGE hydraulic computer model and a numerical scheme to predict bacterial count at each node and on each link of a network. The model provides an effective and each way to visualise on a computer screen variations in water quality in the network. The first model calibration was done using data obtained from a pipe loop system pilot. A validation of the model has been carried out by means of measurement campaigns on various real networks. This predictive model of bacterial growth in distribution systems is a unique approach for the study, diagnosis and management of distributed water quality. This tool is helpful for proposing strategies for the management of distribution systems and treatment plants and to define conditions and locations of high bacterial counts in relation to hydraulic conditions.

scholarly journals Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

2021 ◽  
Vol 12 ◽  
Author(s):  
Carolina Calero Preciado ◽  
Joby Boxall ◽  
Víctor Soria-Carrasco ◽  
Soledad Martínez ◽  
Isabel Douterelo
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Temperature Variation ◽  
Relative Abundance ◽  
Growth Phase ◽  
Distribution Systems ◽  
Bulk Water ◽  
Fungal Communities ◽  
Sequencing Data ◽  
Biofilm Development

Temperature variation can promote physico-chemical and microbial changes in the water transported through distribution systems and influence the dynamics of biofilms attached to pipes, thus contributing to the release of pathogens into the bulk drinking water. An experimental real-scale chlorinated DWDS was used to study the effect of increasing temperature from 16 to 24°C on specific pathogens, bacterial-fungal communities (biofilm and water samples) and determine the risk of material accumulation and mobilisation from the pipes into the bulk water. Biofilm was developed for 30 days at both temperatures in the pipe walls, and after this growth phase, a flushing was performed applying 4 gradual steps by increasing the shear stress. The fungal-bacterial community characterised by Illumina MiSeq sequencing, and specific pathogens were studied using qPCR: Mycobacterium spp., Mycobacterium avium complex, Acanthamoeba spp., Pseudomonas aeruginosa, Legionella pneumophilia, and Stenotrophomonas maltophilia. Sequencing data showed that temperature variation significantly modified the structure of biofilm microbial communities from the early stages of biofilm development. Regarding bacteria, Pseudomonas increased its relative abundance in biofilms developed at 24°C, while fungal communities showed loss of diversity and richness, and the increase in dominance of Fusarium genus. After the mobilisation phase, Pseudomonas continued being the most abundant genus at 24°C, followed by Sphingobium and Sphingomonas. For biofilm fungal communities after the mobilisation phase, Helotiales incertae sedis and Fusarium were the most abundant taxa. Results from qPCR showed a higher relative abundance of Mycobacterium spp. on day 30 and M. avium complex throughout the growth phase within the biofilms at higher temperatures. The temperature impacts were not only microbial, with physical mobilisation showing higher discolouration response and metals release due to the increased temperature. While material accumulation was accelerated by temperature, it was not preferentially to either stronger or weaker biofilm layers, as turbidity results during the flushing steps showed. This research yields new understanding on microbial challenges that chlorinated DWDS will undergo as global temperature rises, this information is needed in order to protect drinking water quality and safety while travelling through distribution systems.

Modelling bacteriological water quality in drinking water distribution systems

1998 ◽  
Vol 38 (8-9) ◽  
pp. 299-307 ◽  
Author(s):  
P. Piriou ◽  
S. Dukan ◽  
L. Kiene
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Bulk Water ◽  
Operating Conditions ◽  
Bacterial Counts ◽  
Drinking Water Distribution Systems ◽  
Biofilm Detachment ◽  
Drinking Water Distribution

Because on-site experimentation raises numerous problems, the study and the modelling of bacterial regrowth phenomena in drinking water distribution systems has been performed using a pipe loop pilot under various operating conditions. As a result, experiments have shown that inlet bacterial counts have little influence on the biofilm behavior which is mainly driven by the amount of available nutrients (BDOC). Biofilm detachment has a significant influence on the increase of suspended bacterial counts with time in relation to the net growth in the bulk water. All these results have been used to develop and validate a deterministic type of model, called PICCOBIO. Some guidelines to achieve water bacteriological stability have been proposed using model simulations.

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