Model Drinking Water Distribution System Research Articles

The destruction of Escherichia coli adhered to pipe surfaces in a model drinking water distribution system via various antibiofilm agents.

The aim of the study is to estimate the effectiveness of three antibiofilm agents against Escherichia coli biofilm that formed in six different types of pipelines. A laboratory-scale water system was built for this work to allow for the creation of biofilm in the pipelines studied. The level of the growth rate of E.coli biofilm cells was monitored over 90days on those tested pipe materials. The results of bacterial cell densities displayed that the highest biofilm growth was observed in the biofilm formed on the iron (Fe) pipe. In contrast, the biofilm formation rate was significantly lower on copper (Cu) pipe compared to other materials. Three antibiofilm agents, including chlorine, silver ions (Ag+ ), and silver nanoparticles (AgNPs), were employed to eradicate the biofilm cells. E.coli counts indicated that AgNPs are more efficient in destructing any formed biofilm cells on all tested materials. At the same time, the chlorine was only useful in the case of biofilm developed on plastic and Cu. However, the antibiofilm efficiency of Ag+ performs similarly to chlorine against E.coli biofilm cells. Ultimately, AgNPs are considred the most powerful antibiofilm agent among the other agents toward the biofilm cells in their maturation stage, which offers an encouraging way for the long-term functioning of water systems. PRACTITIONER POINTS: The growth rate of E.coli biofilm cells was investigated on different materials. The count of biofilm cells developed on iron pipes was higher than other materials. The E.coli biofilm on iron pipe could resist chlorine and AgNPs to a large extent. The developed biofilm on copper pipe was more sensitive to chlorine, Ag+ . and AgNPs. The biofilm cells could be easily eradicated from plastic-based materials with all tested disinfectants.

The limitations of hydrodynamic removal of biofilms from the dead-ends in a model drinking water distribution system

Biofilm formation and removal from dead-ends is a particularly difficult and understudied area of water distribution system biology. In this work, we have built a model drinking water distribution system to probe the effect of different hydrodynamic flow regimes on biofilm formation and removal in the main pipe and in the dead-end. The test rig was built to include all major drinking water distribution system components with materials and dimensions used in standard plumbing systems. We have simulated the effect of stagnant, laminar, turbulent, and intense turbulent flushing conditions on the growth and removal of biofilms from the main pipe and the dead-end. The growth of the biofilm in the main pipe was not prevented at a volumetric flow rate of 9.4 L min−1 and flow velocity of 2 m s−1. Mature biofilms were more difficult to remove. Biofilms grown under shear stress conditions could withstand significantly higher shear stresses than those to which they were exposed to during growth. The biofilms grew twice as fast in the dead-end when flow in the main pipe was turbulent compared to stagnant conditions. Biofilms in the dead-end were not affected by the flushing conditions in the main pipe (Q = 52 L min−1, Re = 9.0 · 104). The computational fluid dynamics simulation suggests that biofilms cannot be hydrodynamically removed from the dead-end at depths that are larger than one pipe diameter. Biofilms beyond this limit present a possible source for reinoculation and recolonization of the rest of the water distribution system.

Linking flow velocity-regulated EPS production with early-stage biofilm formation in drinking water distribution systems

Abstract Hydrodynamics impacts interactions between microbes and their micro-habitats in aqueous systems, thus the study of hydrodynamics is key to understanding the formation and dynamics of biofilms. Yet mechanisms of how microbial responses to hydrodynamics regulate biofilm formation in drinking water distribution systems (DWDS) are underappreciated. Here, we investigated the linkage between early-stage biofilm formation and flow velocity fluctuations in a model DWDS. Results showed that an intermediate velocity (1.0 m/s) enhanced biofilm formation, with the highest biofilm/total cells ratio of 96.91% ± 2.26%. Moreover, the intermediate velocity promoted extracellular polymeric substances (EPS) release, accompanied with lowered zeta potential and elevated hydrophobicity of suspended cells, which could be responsible for surface aggregation. Shifts in biofilm community were observed along with hydrodynamics fluctuations. Intermediate velocity (1.0 m/s) stimulated the dominance of Proteobacteria (78.16%) along with the genus predominance of Pseudomonas, known to secrete large amounts of EPS favoring biofilm formation. Overall, this study provides new understanding of biofilm formation responding to hydrodynamic fluctuations in DWDS.

Quantification of the bacterial community of drinking water-associated biofilms under different flow velocities and changing chlorination regimes

Microbial growth in drinking water distribution systems (DWDS) depends on a great number of factors, and its control represents a great challenge for management of these engineering systems. The present case study assessed the influence that a pair of factors—water chlorination and flow velocity—had on the biofilms formed in a model DWDS in 626 days. The culturable bacteria number and biomass of the biofilms developed under the flow velocities of 0.3 m/s, 0.5 m/s, 0.7 m/s and 1 m/s were determined during three consecutively applied regimes of water chlorination to 0.05 mg/l (in 380 days), 0.42 mg/l (in 46 days) and 0.14 mg/l free chlorine (in 200 days). The results demonstrated that biofilm formation was a prolonged process directly depended on flow velocity at drinking water chlorination to 0.05 mg/l. The increase in the water chlorination to 0.42 mg/l chlorine resulted in both the reduction in culturable bacteria number and biomass removal, but the bacteria killing and the biofilm removal were distinct processes. The biocide action of chlorine was faster and more effective than its biomass removal effect. The chlorine decreasing from 0.42 to 0.14 mg/l resulted in increasing the biofilm HPC densities, although the biomass removal process was still continuing. The study carried out contributes for better understanding the biofilm behavior in DWDS and demonstrates that biofilm formation could be managed within a DWDS through operational decisions on parameters that can be changed and controlled as flow velocity and chlorination to safeguard drinking water quality.

The Relationship Between Iron Oxides/Oxyhydroxides and Toxic Metal Ions in Drinking Water Distribution Systems—A Review

Iron (Fe) oxides/oxyhydroxides in drinking water distribution systems (DWDS), produced by electrochemical, chemical, and biological reactions, can adsorb toxic metal ions, including strontium, lead, arsenic, and vanadium that, if desorbed, generate pulses of drinking water with elevated toxic metal ion concentrations. To illustrate that potential, sorption data for strontium (cation) and vanadium (oxyanion) in functioning DWDS are reviewed. In addition, the influence of flow/no flow on adsorption and desorption of strontium in a model DWDS is included. The reactions that influence adsorption and desorption within a DWDS are extremely complicated and poorly understood. The sorption capacity of Fe oxhydroxides varies with surface area, which in turn varies with source water and disinfectant. Desorption and release can be triggered by changes in source water, disinfection chemicals, or flow. Because of the interrelatedness of adsorption/desorption and Fe corrosion products, subtle changes in DWDS operating p...

Impact of environmental factors on legionella populations in drinking water.

To examine the impact of environmental factors on Legionella in drinking water distribution systems, the growth and survival of Legionella under various conditions was studied. When incubated in tap water at 4 °C, 25 °C, and 32 °C, L. pneumophila survival trends varied amongst the temperatures, with the stable populations maintained for months at 25 °C and 32 °C demonstrating that survival is possible at these temperatures for extended periods in oligotrophic conditions. After inoculating coupons of PVC, copper, brass, and cast iron, L. pneumophila colonized biofilms formed on each within days to a similar extent, with the exception of cast iron, which contained 1-log less Legionella after 90 days. L. pneumophila spiked in a model drinking water distribution system colonized the system within days. Chlorination of the system had a greater effect on biofilm-associated Legionella concentrations, with populations returning to pre-chlorination levels within six weeks. Biofilms sampled from drinking water meters collected from two areas within central Arizona were analyzed via PCR for the presence of Legionella. Occurrence in only one area indicates that environmental differences in water distribution systems may have an impact on the survival of Legionella. These results document the impact of different environmental conditions on the survival of Legionella in water.

Structure and microbial diversity of biofilms on different pipe materials of a model drinking water distribution systems.

The experiment was conducted in three model drinking water distribution systems (DWDSs) made of unplasticized polyvinyl chloride (PVC), silane cross-linked polyethylene (PEX) and high density polyethylene (HDPE) pipes to which tap water was introduced. After 2 years of system operation, microbial communities in the DWDSs were characterized with scanning electron microscopy, heterotrophic plate count, and denaturing gradient gel electrophoresis. The most extensive biofilms were found in HDPE pipes where bacteria were either attached to mineral deposits or immersed in exopolymers. On PEX surfaces, bacteria did not form large aggregates; however, they were present in the highest number (1.24 × 107 cells cm−2). PVC biofilm did not contain mineral deposits but was made of single cells with a high abundance of Pseudomonas aeruginosa, which can be harmful to human health. The members of Proteobacteria and Bacteroidetes were found in all biofilms and the water phase. Sphingomonadales and Methylophilaceae bacteria were found only in PEX samples, whereas Geothrix fermentans, which can reduce Fe(III), were identified only in PEX biofilm. The DNA sequences closely related to the members of Alphaproteobacteria were the most characteristic and intense amplicons detected in the HDPE biofilm.

Bayesian Belief Networks for predicting drinking water distribution system pipe breaks

In this paper, we use Bayesian Belief Networks (BBNs) to construct a knowledge model for pipe breaks in a water zone. To the authors’ knowledge, this is the first attempt to model drinking water distribution system pipe breaks using BBNs. Development of expert systems such as BBNs for analyzing drinking water distribution system data is not only important for pipe break prediction, but is also a first step in preventing water loss and water quality deterioration through the application of machine learning techniques to facilitate data-based distribution system monitoring and asset management. Due to the difficulties in collecting, preparing, and managing drinking water distribution system data, most pipe break models can be classified as “statistical–physical” or “hypothesis-generating.” We develop the BBN with the hope of contributing to the “hypothesis-generating” class of models, while demonstrating the possibility that BBNs might also be used as “statistical–physical” models. Our model is learned from pipe breaks and covariate data from a mid-Atlantic United States (U.S.) drinking water distribution system network. BBN models are learned using a constraint-based method, a score-based method, and a hybrid method. Model evaluation is based on log-likelihood scoring. Sensitivity analysis using mutual information criterion is also reported. While our results indicate general agreement with prior results reported in pipe break modeling studies, they also suggest that it may be difficult to select among model alternatives. This model uncertainty may mean that more research is needed for understanding whether additional pipe break risk factors beyond age, break history, pipe material, and pipe diameter might be important for asset management planning.

Strontium adsorption and desorption reactions in model drinking water distribution systems

Divalent cationic strontium (Sr 2+ ) adsorption to and desorption from iron corrosion products were examined in two model drinking water distribution systems (DWDS). One system was maintained with chlorine-disinfected drinking water and the other with the same water with secondary chloramine disinfection. Flow conditions simulated primary transmission lines (constant flow) and residential mains (periods of stagnation). Accumulation of Sr 2+ to iron corrosion products in model DWDS was independent of disinfection type. Adsorption and desorption mechanisms are discussed. X-ray adsorption near edge structure (XANES) spectroscopy and linear combination fitting determined Sr 2+ was primarily associated with iron oxyhydroxide corrosion products. At the end of the desorption study, the amount of Sr 2+ remaining in iron corrosion products equilibrated to approximate levels observed at the end of the constant flow adsorption experiments. These results suggest that enhanced iron corrosion product loading of Sr 2+ during stagnation could be short lived under constant flow conditions. Differences between adsorption and desorption based on disinfection type (chlorine versus chlorine plus chloramine) cannot be used to control Sr 2+ desorption.

Characterization and identification of a chlorine-resistant bacterium, Sphingomonas TS001, from a model drinking water distribution system

This study describes the identification and characterization of a new chlorine resistant bacterium, Sphingomonas TS001, isolated from a model drinking water distribution system. The isolate was identified by 16s rRNA gene analysis and morphological and physiological characteristics. Phylogenetic analysis indicates that TS001 belongs to the genus Sphingomonas. The model distribution system HPC results showed that, when the chlorine residual was greater than 0.7mgL−1, 100% of detected heterotrophic bacteria (HPC) was TS001. The bench-scale inactivation efficiency testing showed that this strain was very resistant to chlorine, and 4mgL−1 of chlorine with 240min retention time provided only approximately 5% viability reduction of TS001. In contrast, a 3-log inactivation (99.9%) was obtained for UV fluencies of 40mJcm−2. A high chlorine-resistant and UV sensitive bacterium, Sphingomonas TS001, was documented for the first time.

Nutrient-Induced Growth of Coliform and HPC Bacteria in Drinking-Water Pipes

We conducted a study on a model drinking water distribution system to evaluate the impact of nutrient in the form of sodium acetate on the growth and survival of coliform and heterotrophic plate count (HPC) bacteria for a maximum of 21 days residence time of water in pipes. Our results show that, besides the nutrient added and the absence of any additional source of contamination and additional supply of nutrient, there was significant growth of the above mentioned bacteria in the pipes and bottles for a couple of days, after which the bacterial population began to decrease. The results indicate that the bacteria used the nutrient to grow and multiply until the nutrient was totally consumed and became depleted in the bulk water phase, after which the bacterial population reached a near stationary level and subsequently declined. This suggests the death of some of the bacteria and their dead cells were used by other bacteria for growth and survival. Using a detection limit of 3.3 CFU/100 mL for the coliforms, the study shows that after sometime, no bacteria were found in the water phase of the pipe, however, the biofilm in the pipes still harbored some of the bacteria. The results have revealed that the bacteria also have the tendency to move from the water phase to the biofilm since the latter provides a more suitable environment for bacteria to thrive on and grow, thus prolonging their survival in the system.

Persistence and decontamination of surrogate radioisotopes in a model drinking water distribution system

Contamination of a model drinking water system with surrogate radioisotopes was examined with respect to persistence on and decontamination of infrastructure surfaces. Cesium and cobalt chloride salts were used as surrogates for cesium-137 and cobalt-60. Studies were conducted in biofilm annular reactors containing heavily corroded iron surfaces formed under shear and constantly submerged in drinking water. Cesium was not detected on the corroded iron surface after equilibration with 10 and 100 mg L −1 solutions of cesium chloride, but cobalt was detected on corroded iron coupons at both initial concentrations. The amount of adhered cobalt decreased over the next six weeks, but was still present when monitoring stopped. X-ray absorption near-edge spectroscopy (XANES) showed that adhered cobalt was in the III oxidation state. The adsorbed cobalt was strongly resistant to decontamination by various physicochemical methods. Simulated flushing, use of free chlorine and dilute ammonia were found to be ineffective whereas use of aggressive methods like 14.5 M ammonia and 0.36 M sulfuric acid removed 37 and 92% of the sorbed cobalt, respectively.

Influence of phosphorus on biofilm formation in model drinking water distribution systems

This study investigated the effects of phosphorus on biofilm formation via annular reactor systems in terms of biofilm cell growth, exopolysaccharide (EPS) production, biofilm structure and cell metabolic potential. Drinking water biofilms were developed in annular reactors with supplement of carbon and different levels of phosphorus. The biofilm formation was monitored over a period of 30 days. Biofilm related parameters were examined by various methods, which included heterotrophic plate count, total carbohydrate content, confocal laser scanning microscopy and GN2 microplate assay. Our results showed that phosphorus addition can promote the biofilm cell growth (cell count increased about 1 log with addition of 30 and 300 microg l(-1) of phosphorus). However, the addition of 30 and 300 microg l(-1) of phosphorus caused 81% and 77% decrease in EPS production, respectively. The results of biofilm structure analysis showed that the addition of 30 and 300 microg l(-1) of phosphorus can induce thicker and less homogeneous biofilms with more biomass. Furthermore, the addition of 30 and 300 microg l(-1) of phosphorus dramatically increased the biofilm cell metabolic potential. The addition of 3 microg l(-1) of phosphorus was found to have minor effects on the parameters examined. The results indicate phosphorus addition to drinking water distribution system (DWDS) has a complicated effect on the biofilm formation. As the addition of phosphorus at certain levels can affect the biofilm growth in DWDS, care should be taken when phosphate-based corrosion inhibitors are used in the DWDS.

Biofilm control using chlorine-based disinfectants in model drinking water distribution systems

Model distribution systems (annular reactors) were operated to investigate the biofilm disinfection efficacies of three disinfectants: free chlorine, monochloramine and combination of free chlorine and silver ion. Biofilm cell number, coverage and structure were examined. At the same dosages, monochloramine showed the poorest biofilm disinfection efficiency compared to free chlorine and combination of free chlorine and silver ion. 40 μg/l of Ag+ showed positive effect to both two dosages of chlorine (0.5 mg/l and 1 mg/l) to disinfect biofilm bacteria. In addition, combinations of free chlorine and silver ion were found to achieve the highest biofilm coverage reduction, while monochloramine showed the least biofilm removal. Biofilm structure could also be affected by different testing agents.

Changes in microbiological quality in model distribution systems after switching from chlorine or chloramines to chlorine dioxide

North American drinking water utilities are currently re-evaluating their disinfection strategies for controlling microbiological growth in distribution systems. Most water systems in North America use free chlorine as a secondary disinfectant. Since chlorine is known to form potentially carcinogenic byproducts in drinking water, utilities are looking for an alternative to maintain a disinfectant residual in the distribution system. The objective of this study was to evaluate the response of model drinking water distribution systems to a change in disinfectant from either free chlorine or chloramines to chlorine dioxide, in terms of its impact on microbiological water quality (bulk water and biofilm). Switching from a chlorine residual of 0.5 mg/L to a chlorine dioxide residual of 0.25 mg/L did not impact (negatively or positively) microbial water quality as quantified by heterotrophic and total cell counts (sample size = 8 data points). Thus, on the basis of the mass of disinfectant applied, chlorine dioxide was more efficient than free chlorine at controlling microbiological growth in the model distribution system. Similarly, chlorine dioxide was more efficient than chloramines, as a chlorine dioxide residual of 0.25 mg/L inactivated 0.75–1 log more suspended organisms than 1.0 mg/L residual of chloramines. Therefore, under the tested conditions, chlorine showed similar or better disinfection efficiency than free chlorine and chloramines, respectively.

Identification of Bacteria in Biofilm and Bulk Water Samples from a Nonchlorinated Model Drinking Water Distribution System: Detection of a Large Nitrite-Oxidizing Population Associated with Nitrospira spp

In a model drinking water distribution system characterized by a low assimilable organic carbon content (<10 microg/liter) and no disinfection, the bacterial community was identified by a phylogenetic analysis of rRNA genes amplified from directly extracted DNA and colonies formed on R2A plates. Biofilms of defined periods of age (14 days to 3 years) and bulk water samples were investigated. Culturable bacteria were associated with Proteobacteria and Bacteriodetes, whereas independently of cultivation, bacteria from 12 phyla were detected in this system. These included Acidobacteria, Nitrospirae, Planctomycetes, and Verrucomicrobia, some of which have never been identified in drinking water previously. A cluster analysis of the population profiles from the individual samples divided biofilms and bulk water samples into separate clusters (P = 0.027). Bacteria associated with Nitrospira moscoviensis were found in all samples and encompassed 39% of the sequenced clones in the bulk water and 25% of the biofilm community. The close association with Nitrospira suggested that a large part of the population had an autotrophic metabolism using nitrite as an electron donor. To test this hypothesis, nitrite was added to biofilm and bulk water samples, and the utilization was monitored during 15 days. A first-order decrease in nitrite concentration was observed for all samples with a rate corresponding to 0.5 x 10(5) to 2 x 10(5) nitrifying cells/ml in the bulk water and 3 x 10(5) cells/cm(2) on the pipe surface. The finding of an abundant nitrite-oxidizing microbial population suggests that nitrite is an important substrate in this system, potentially as a result of the low assimilable organic carbon concentration. This finding implies that microbial communities in water distribution systems may control against elevated nitrite concentrations but also contain large indigenous populations that are capable of assisting the depletion of disinfection agents like chloramines.

Effects of temperature and biodegradable organic matter on control of biofilms by free chlorine in a model drinking water distribution system

This study used annular reactors (AR) to investigate, under controlled laboratory conditions, the effects of temperature and biodegradable organic matter (BOM) on the free chlorine residual needed to control biofilm accumulation, as measured by heterotrophic plate count (HPC) bacteria. Biofilm was grown on PVC coupons, initially in the absence of chlorine, at 6, 12, and 18 degrees C, in the presence and absence of a BOM supplement (250 microg C/L) added as acetate. During the early stages of chlorine addition, when no measurable free chlorine residual was present, a reduction in biofilm HPC numbers was observed. Subsequently, once sufficient chlorine was added to establish a residual, the biofilm HPC numbers expressed as log CFU/cm2 fell exponentially with the increase in free chlorine residual. Temperature appeared to have an important effect on both the chlorine demand of the system and the free chlorine residual required to control the biofilm HPC numbers to the detection limit (3.2 Log CFU/cm2). For the water supplemented with BOM, a strong linear correlation was found between the temperature and the free chlorine residual required to control the biofilm. At 6 degrees C, the presence of a BOM supplement appeared to substantially increase the level of free chlorine residual required to control the biofilm. The results of these laboratory experiments provide qualitative indications of effects that could be expected in full-scale systems, rather than to make quantitative predictions.

Survival of Mycobacterium avium in a model distribution system

A pilot study was designed to examine the impact of nutrient levels, pipe materials, and disinfection on the survival of M. avium in model drinking water distribution system biofilms. Studies showed that the survival of the organism was dependant upon a complex interaction between pipe surface, nutrient levels, and disinfectants. The findings showed that when no disinfection was applied, M. avium could be recovered from biofilms at nutrient levels of 50 μg/L assimilable organic carbon. M. avium concentrations were lower on copper pipe surfaces following disinfection with free chlorine as compared to monochloramine. However, due to the interference of corrosion products, chloramination of iron pipe surfaces controlled M. avium levels better than free chlorine. These data demonstrate the significance of pipe materials on the survival of M. avium complex in biofilms. Elimination of competitive heterotrophic bacteria on copper pipe surfaces by the application of disinfection resulted in a population of nearly 100% M. avium. Heat treatment of M. avium biofilms was affected by the pipe composition and organic content of the water. Effluent temperatures >53°C were required to control the occurrence of M. avium in the pipeline system. Although additional studies are required using improved detection methods, the results of this investigation suggest that reducing the biodegradable organic material in drinking water, control of corrosion, maintenance of an effective disinfectant residual, and management of hot water temperatures can help limit the occurrence of M. avium complex in drinking water biofilms.

Long-term succession of structure and diversity of a biofilm formed in a model drinking water distribution system.

In this study, we examined the long-term development of the overall structural morphology and community composition of a biofilm formed in a model drinking water distribution system with biofilms from 1 day to 3 years old. Visualization and subsequent quantification showed how the biofilm developed from an initial attachment of single cells through the formation of independent microcolonies reaching 30 micro m in thickness to a final looser structure with an average thickness of 14.1 micro m and covering 76% of the surface. An analysis of the community composition by use of terminal restriction fragment length polymorphisms showed a correlation between the population profile and the age of the sample, separating the samples into young (1 to 94 days) and old (571 to 1,093 days) biofilms, whereas a limited spatial variation in the biofilm was observed. A more detailed analysis with cloning and sequencing of 16S rRNA fragments illustrated how a wide variety of cells recruited from the bulk water initially attached and resulted in a species richness comparable to that in the water phase. This step was followed by the growth of a bacterium which was related to Nitrospira, which constituted 78% of the community by day 256, and which resulted in a reduction in the overall richness. After 500 days, the biofilm entered a stable population state, which was characterized by a greater richness of bacteria, including Nitrospira, Planctomyces, Acidobacterium, and Pseudomonas. The combination of different techniques illustrated the successional formation of a biofilm during a 3-year period in this model drinking water distribution system.

Dynamics of biofilm formation in a model drinking water distribution system

Research Article| November 01 2002 Dynamics of biofilm formation in a model drinking water distribution system Rasmus Boe-Hansen; Rasmus Boe-Hansen 1Environment & Resources DTU, Technical University of Denmark, Building 115, 2800 Kgs. Lyngby, Denmark2DHI – Water and environment, Agern allé 11, 2970 Hørsholm, Denmark Tel: +45 45251571 Fax: +45 45932850; E-mail: rbh@er.dtu.dk Search for other works by this author on: This Site PubMed Google Scholar Hans-Jørgen Albrechtsen; Hans-Jørgen Albrechtsen 1Environment & Resources DTU, Technical University of Denmark, Building 115, 2800 Kgs. Lyngby, Denmark Search for other works by this author on: This Site PubMed Google Scholar Erik Arvin; Erik Arvin 1Environment & Resources DTU, Technical University of Denmark, Building 115, 2800 Kgs. Lyngby, Denmark Search for other works by this author on: This Site PubMed Google Scholar Claus Jørgensen Claus Jørgensen 2DHI – Water and environment, Agern allé 11, 2970 Hørsholm, Denmark Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2002) 51 (7): 399–406. https://doi.org/10.2166/aqua.2002.0036 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Twitter LinkedIn Tools Icon Tools Cite Icon Cite Permissions Search Site Search nav search search input Search input auto suggest search filter All ContentAll JournalsThis Journal Search Advanced Search Citation Rasmus Boe-Hansen, Hans-Jørgen Albrechtsen, Erik Arvin, Claus Jørgensen; Dynamics of biofilm formation in a model drinking water distribution system. Journal of Water Supply: Research and Technology-Aqua 1 November 2002; 51 (7): 399–406. doi: https://doi.org/10.2166/aqua.2002.0036 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex The dynamics of biofilm formation in non-chlorinated groundwater-based drinking water was studied in a model distribution system. The formation of biofilm was closely monitored for a period of 522 days by total bacterial counts (AODC), heterotrophic plate counts (R2A media), and ATP content determinations. The biofilm grew at a rate of 0.030±0.002 day−1 reaching quasi-stationary state at 2.6×106 cells/cm2 after approximately 200 days. The low substrate level in the bulk phase (AOC at approximately 6 µg ac-C/l) most likely caused the relatively slow biofilm formation rate observed. During the maturation of the biofilm, the bacterial community changed properties in terms of cell-specific ATP content and culturability of the bacteria. biofilm, drinking water, formation, growth, stationary phase This content is only available as a PDF. © IWA Publishing 2002 You do not currently have access to this content.