scholarly journals Dynamic response of biofilm to pipe surface and fluid velocity

2003 ◽  
Vol 47 (5) ◽  
pp. 57-59 ◽  
Author(s):  
T.E. Cloete ◽  
D. Westaard ◽  
S.J. van Vuuren
Keyword(s):  
Distribution System ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Water Distribution ◽  
Fluid Velocity ◽  
Flow Conditions ◽  
Dapi Staining ◽  
Biofilm Growth ◽  
Pipe Surface ◽  
Viable Bacteria

Biofouling in pipelines is a function of the inner roughness of the specific piping material that is used in distribution systems and the concomitant biofilm formation. To test the effect of velocity on the growth of biofilm, a Roto-Scope was designed and built to imitate different materials and flow conditions in potable water distribution systems. Biofilm formation was monitored using DAPI staining and the total number of viable bacteria. Increased velocity in the system resulted in a specific detaching velocity, where the formation of biofilm was limited. Most of the time these detaching velocities were not the highest velocities tested. The range of detaching velocities was between ±3 m.s−1 and 4 m.s−1. A flow velocity within this range would thus be ideal for achieving reduced biofilm growth in a distribution system.

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.

scholarly journals Assessment of probable causes of chlorine decay in water distribution systems of Gaborone city, Botswana

Water SA ◽  
2019 ◽  
Vol 45 (2 April) ◽  
Author(s):  
Denis Nono ◽  
Phillimon T Odirile ◽  
Innocent Basupi ◽  
Bhagabat P Parida
Keyword(s):  
Water Quality ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Inorganic Compounds ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Biofilm Growth ◽  
Reaction Rate Constants ◽  
Chlorine Decay

Assessment of probable causes of chlorine decay in water distribution systems of Gaborone city, Botswana Gaborone city water distribution system (GCWDS) is rapidly expanding and has been faced with the major problems of high water losses due to leakage, water shortages due to drought and inadequate chlorine residuals at remote areas of the network. This study investigated the probable causes of chlorine decay, due to pipe wall conditions and distribution system water quality in the GCWDS. An experimental approach, which applied a pipe-loop network model to estimate biofilm growth and chlorine reaction rate constants, was used to analyse pipe wall chlorine decay. Also, effects of key water quality parameters on chlorine decay were analysed. The water quality parameters considered were: natural organic matter (measured by total organic carbon, TOC; dissolved organic carbon, DOC; and ultraviolet absorbance at wavelength 254, UVA-254, as surrogates), inorganic compounds (iron and manganese) and heterotrophic plate count (HPC). Samples were collected from selected locations in the GCWDS for analysis of water quality parameters. The results of biofilm growth and chlorine reaction rate constants revealed that chlorine decay was higher in pipe walls than in the bulk of water in the GCWDS. The analysis of key water quality parameters revealed the presence of TOC, DOC and significant levels of organics (measured by UVA-254), which suggests that organic compounds contributed to chlorine decay in the GCWDS. However, low amounts of iron and manganese (< 0.3 mg/L) indicated that inorganic compounds may have had insignificant contributions to chlorine decay. The knowledge gained on chlorine decay would be useful for improving water treatment and network operating conditions so that appropriate chlorine residuals are maintained to protect the network from the risks of poor water quality that may occur due to the aforementioned problems.

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

&lt;p&gt;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.&lt;/p&gt;

Investigation into biofilms in a local drinking water distribution system

Biofilms ◽  
2005 ◽  
Vol 2 (1) ◽  
pp. 19-25 ◽  
Author(s):  
J. Y. Hu ◽  
B. Yu ◽  
Y. Y. Feng ◽  
X. L. Tan ◽  
S. L. Ong ◽  
...  
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Plate Count ◽  
Residual Chlorine ◽  
Biofilm Growth ◽  
Water Plant ◽  
Biofilm Development

Biofilm growth within a water distribution system could lead to operational problems such as pipe corrosion, water quality deterioration and other undesirable impacts in water distribution systems. With the high ambient temperatures experienced in Singapore, the operating environment in water distribution systems is expected to be more conducive to biofilm development. We have recently conducted a survey on biofilms potentially present in a local water distribution system.The survey results indicated that residual chlorine (±standard deviation) decreased from 1.49±0.61 mg/l (water plant outlets) to 0.82±0.21 mg/l (block pipes) or 0.18±0.06 mg/l (unit pipes), respectively. Consumed chlorine, instead of residual chlorine, was found to be correlated with biofilm bacterial population. Assimilable organic carbon (AOC) level was 160±66 μg acetate C/l, and AOC:PO4-P:NO3-N was about 8:13:1. Carbon source seemed to be the limiting nutrient for bacterial growth. The concentration of iron increased from <0.04 mg/l (water plant outlets) to 0.22±0.10 mg/l (all sites). All samples showed negative results in a coliform test. The average heterotrophic plate count (HPC) for the suspended bacteria was 20 colony-forming units (c.f.u.)/ml (2 days, 35 °C) or 290 c.f.u./ml (8 days, 35 °C). The average HPC for the biofilm bacteria was 6500 c.f.u./cm2 (2 days, 35 °C) or 29000 c.f.u./cm2 (8 days, 35 °C). High HPC values in samples B2a, B2b and B3a (representing biofilm samples at site 2 from block/unit pipes and biofilm samples at site 3 from block pipes, respectively) illustrated that the relevant sample sites had a higher probaboility of biofilm growth.

Microbial Diversity and their Biofilm Formation Potential in Pipes of Water Distribution System

2020 ◽  
Vol 17 (4) ◽  
pp. 113-117
Author(s):  
Rajanbir Kaur ◽  
Rajinder Kaur
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Water Distribution ◽  
Potable Water ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Growth Patterns ◽  
Water Borne

Microbes are ubiquitous in surface as well as in ground water and some of them can make their way into potable water distribution systems. Contaminated soil with human and animal fecal matter, ill-maintained water and sewage pipelines, poor sanitation and personal hygiene are the main factors responsible for the presence of microbial pathogens in the drinking water. The presence of water-borne microbes in the potable drinking water systems determines its quality. Common microbes present in contaminated water are Shigella, Escherichia coli, Vibrio cholerae, Pseudomonas sp, Salmonella sp etc. The water-borne pathogens that reside and reproduce in water distribution system causes infection of gastrointestinal tract, urinary tract, skin, and lymph nodes. When these pathogens enter into the water distribution system pipelines they form biofilms. The formation of biofilm is a key component in microbial studies. Biofilm is the sessile aggregation of bacterial cells that adhere to each other on living or non-living surfaces and forms extracellular polymeric substances (EPS). The surface physico-chemical properties of both bacteria and substratum were important for the establishment of bacterial adhesion. Bacteria forming biofilms possesses different growth patterns, responds to specific micro-environmental conditions for the formation of structurally complex mature biofilms. In water distribution systems, adhesion of microbes to the water pipelines initiate biofilm formation which in return reduces the quality of potable water and increases the corrosion of pipes.

Biofilm formation potentials in drinking waters treated by different advanced treatment processes

2002 ◽  
Vol 2 (4) ◽  
pp. 97-104 ◽  
Author(s):  
S. Okabe ◽  
T. Kokazi ◽  
Y. Watanabe
Keyword(s):  
Water Treatment ◽  
Distribution System ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Water Distribution ◽  
Treatment Plant ◽  
Biological Activated Carbon ◽  
Treatment Processes ◽  
Biological Treatments ◽  
The Impact

When biodegradable organic matter and other nutrients, such as ammonia and phosphorus, are not sufficiently removed during water treatment, bacteria may proliferate in the water distribution system. Bacterial regrowth deteriorates water quality (taste and odor), accelerates corrosion, and potentially increases the risk of microbial diseases. Therefore, this research was conducted to evaluate the impact of four different advanced water treatment processes, including biological treatments such as a rotating biofilm membrane reactor (RBMR) and a biological activated carbon (BAC) filter and ultrafiltration (UF), on reduction of nutrient levels and biofilm formation potentials of the treated water entering model distribution systems (annular reactors). Our results revealed that biological treatments significantly improved the “biostability” of water leaving from the treatment plant. On average, The RBMR and BAC filter reduced easily assimilable organic carbon (AOC) concentration by half when compared with conventional treatment (multi-media filtration; MF) and ultrafiltration (from 35-49 to 18-23 mg C L-1). Consequently, biofilm formation potential was reduced by a factor of 5 to 10 (from 3,200-5,100 to 490-710 pg ATP cm-2). With respect to “biostability” of water, ultrafiltration was less effective in reducing AOC concentrations. In addition, the impact of chlorine disinfection on biofilm accumulation and AOC levels in the distribution system were studied.

Modeling of biofilm in the water distribution system

2008 ◽  
Vol 8 (5) ◽  
pp. 513-518
Author(s):  
Tai-Lee Hu ◽  
Chenfang Lin ◽  
Wei-Yu Chen
Keyword(s):  
Distribution System ◽  
Biofilm Formation ◽  
Water Distribution ◽  
Water Distribution System ◽  
Pipe Wall ◽  
Model Simulation ◽  
Tap Water ◽  
Growth Data ◽  
Data Set ◽  
Biofilm Growth

In order to understand the growth of biofilm and to serve as the basis of cleaning the water distribution pipeline, this study used a multi-attachment dynamic model to simulate the growth of microorganisms' attachment to the pipe wall. The model had considered attachment, detachment, and propagating factors. The attachment and detachment factors are divided into “cell to cell” and “cell to substratum”. Factors for biofilm growth included two possibilities, which was “lateral growth” and “vertical growth”. Data set of the biofilm biomass from a laboratory scale water distribution system was measured. The data and the model simulation curves were compared so as to justify the performance of the model. The results show that several sets of parameters could be identified. From the simulation of biofilm biomass in the pipeline, the microbial growth related with the incubation time. Due to nutrients being restricted, the biomass of biofilm in the water distribution system did not continue to grow and reached a maximum at about Day 40. From the simulation results, it was suggested the time of cleaning the water distribution pipeline be shortened to one or two months. The model was applied to simulate the tap water biofilm in the pipeline of Kaohsiung city, the second largest in Taiwan with 1.5 million population. The results revealed various levels of risks and the proportionality between the biomass in the water and the growth rate of biofilm. However, most households had the purifying facility of a reverse osmosis system. From the simulation, the facility proved its effectiveness for preventing the intervention of bacteria from the biofilm formation in the distribution pipelines.

scholarly journals Aggregation and biofilm formation of bacteria isolated from domestic drinking water

2013 ◽  
Vol 13 (4) ◽  
pp. 1016-1023 ◽  
Author(s):  
B. Ramalingam ◽  
R. Sekar ◽  
J. B. Boxall ◽  
C. A. Biggs
Keyword(s):  
Drinking Water ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Water Distribution ◽  
Control Strategies ◽  
Extended Period ◽  
Dapi Staining ◽  
Drinking Water Distribution Systems ◽  
Potential Control ◽  
Pure Cultures

The objective of this study was to investigate the autoaggregation, coaggregation and biofilm formation of four bacteria namely Sphingobium, Xenophilus, Methylobacterium and Rhodococcus isolated from drinking water. Auto and coaggregation studies were performed by both qualitative (DAPI staining) and semi-quantitative (visual coaggregation) methods and biofilms produced by either pure or dual-cultures were quantified by crystal violet method. Results from the semi-quantitative visual aggregation method did not show any immediate auto or coaggregation, which was confirmed by the 4′,6 diamidino-2-phenylindole (DAPI) staining method. However, after 2 hours, Methylobacterium showed the highest autoaggregation of all four isolates. The Methylobacterium combinations showed highest coaggregation between dual species at extended period of times (72 hours). Biofilm formation by pure cultures was negligible in comparison to the quantity of biofilm produced by dual-species biofilms. The overall results show that coaggregation of bacteria isolated from drinking water was mediated by species-specific and time-dependent interactions with a synergistic type of biofilm formation. The results of this study are therefore a useful step in assisting the development of potential control strategies by identifying specific bacteria that promote aggregation or biofilm formation in drinking water distribution systems.

scholarly journals Application of genetic programming to modeling pipe failures in water distribution systems

2010 ◽  
Vol 13 (3) ◽  
pp. 419-428 ◽  
Author(s):  
Qiang Xu ◽  
Qiuwen Chen ◽  
Weifeng Li
Keyword(s):  
Genetic Programming ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Pipe Failure ◽  
Beijing City ◽  
Failure Data ◽  
Processing Strategies ◽  
Gis Data ◽  
Failure Models

The water loss from a water distribution system is a serious problem for many cities, which incurs enormous economic and social loss. However, the economic and human resource costs to exactly locate the leakage are extraordinarily high. Thus, reliable and robust pipe failure models are demanded to assess a pipe's propensity to fail. Beijing City was selected as the case study area and the pipe failure data for 19 years (1987–2005) were analyzed. Three different kinds of methods were applied to build pipe failure models. First, a statistical model was built, which discovered that the ages of leakage pipes followed the Weibull distribution. Then, two other models were developed using genetic programming (GP) with different data pre-processing strategies. The three models were compared thereafter and the best model was applied to assess the criticality of all the pipe segments of the entire water supply network in Beijing City based on GIS data.

scholarly journals A Head Formulation for the Steady-State Analysis of Water Distribution Systems Using an Explicit and Exact Expression of the Colebrook–White Equation

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1163
Author(s):  
Mengning Qiu ◽  
Avi Ostfeld
Keyword(s):  
Steady State ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Solution Method ◽  
Water Distribution System ◽  
Academic Research ◽  
Exact Expression ◽  
Contamination Source

Steady-state demand-driven water distribution system (WDS) solution is the bedrock for much research conducted in the field related to WDSs. WDSs are modeled using the Darcy–Weisbach equation with the Swamee–Jain equation. However, the Swamee–Jain equation approximates the Colebrook–White equation, errors of which are within 1% for ϵ/D∈[10−6,10−2] and Re∈[5000,108]. A formulation is presented for the solution of WDSs using the Colebrook–White equation. The correctness and efficacy of the head formulation have been demonstrated by applying it to six WDSs with the number of pipes ranges from 454 to 157,044 and the number of nodes ranges from 443 to 150,630. The addition of a physically and fundamentally more accurate WDS solution method can improve the quality of the results achieved in both academic research and industrial application, such as contamination source identification, water hammer analysis, WDS network calibration, sensor placement, and least-cost design and operation of WDSs.

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