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Impact of Water Chemistry on Lead Carbonate Dissolution in Drinking Water Distribution Systems

Impact of Water Chemistry on Lead Carbonate Dissolution in Drinking Water Distribution Systems

According to the drinking water quality guideline published by the World Health Organization (WHO), the recommended provisional limit of lead in drinking water is 10 µg/L (ppb). This limit is adopted as the drinking water standard in many countries including Canada, Australia, China and European Union, while in United States the guideline value is 15 µg/L [17]-[21]. Dissolution of lead in drinking water, also known as plumbosol- vency, is mainly because of lead containing materials used in water distribution systems and household plumb- ing, which is influenced by various water quality characteristics. Existing corrosion scales in lead pipes, solders, brass fittings and plumbing fixtures used in drinking water distribution systems are currently considered as a major problem for municipalities [9] [22] [23]. Destabilization of the corrosion scale in the distribution systems is the main source of lead in drinking water. X-ray diffraction (XRD) results of pipes collected from distribution system in City of London, Ontario, Canada by Kim and Herrera [22] have shown the main lead solid phase in the corrosion scale is hydrocerussite (Pb 3 (CO 3 ) 2 (OH) 2) . Additionally, in few cases cerussite (PbCO 3 ) was also
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Biofilm microbiome (re)growth dynamics in drinking water distribution systems are impacted by chlorine concentration

Biofilm microbiome (re)growth dynamics in drinking water distribution systems are impacted by chlorine concentration

Biofilms are the dominant form of microbial loading (and organic material) within drinking water distribution systems (DWDS), yet our understanding of DWDS microbiomes is focused on the more easily accessible bulk-water. Disinfectant residuals are commonly provided to manage planktonic microbial activity in DWDS to safeguard water quality and public health, yet the impacts on the biofilm microbiome are largely unknown. We report results from a full-scale DWDS facility used to develop biofilms naturally, under one of three chlorine concentrations: Low, Medium, or High. Increasing the chlorine concentration reduced the bacterial concentration within the biofilms but quantities of fungi were unaffected. The chlorine regime was influential in shaping the community structure and composition of both taxa. There were microbial members common to all biofilms but the abundance of these varied such that at the end of the Growth phase the communities from each regime were distinct. Alpha-, Beta-, and Gamma-proteobacteria were the most abundant bacterial classes; Sordariomycetes, Leotiomycetes, and Microbotryomycetes were the most abundant classes of fungi. Mechanical cleaning was shown to immediately reduce the bacterial and fungal concentrations, followed by a lag effect on the microbiome with continued decreases in quantity and ecological indices after cleaning. However, an established community remained, which recovered such that the microbial compositions at the end of the Re-growth and initial Growth phases were similar. Interestingly, the High-chlorine biofilms showed a significant elevation in bacterial concentrations at the end of the Re-growth (after cleaning) compared the initial Growth, unlike the other regimes. This suggests adaptation to a form a resilient biofilm with potentially equal or greater risks to water quality as the other regimes. Overall, this study provides critical insights into the interaction between chlorine and the microbiome of DWDS biofilms representative of real networks, implications are made for the operation and maintenance of DWDS disinfectant and cleaning strategies.
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Application of optical tomography in the study of discolouration in drinking water distribution systems

Application of optical tomography in the study of discolouration in drinking water distribution systems

The intended operating environment for the method which has been described in this paper is in the lab. Under nor- mal conditions, the particle concentration in drinking water is much too low to be detectable with the present optical set- up, except when hydraulic disturbances cause discolouration. In the lab, it is possible and often desirable to work with par- ticle concentrations which are much higher than in drinking water distribution systems to facilitate observation and re- duce time scales of e.g. accumulation. The first investigation in which this technique has been applied is the experimental verification of a theoretical mechanism map for turbulent par- ticle deposition in drinking water distribution systems (Floris et al., 2011). This presents results describing the conditions of initiation of particle deposition by turbophoresis, building on theoretical predictions by van Thienen et al. (2011b). A number of additional research areas in drinking water distri- bution in which the method can be applied can be thought of, such as particle resuspension, saltation and bed transport.
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Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems

Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems

Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems FURNASS, W.. B Available from Sheffield Hallam University Research[r]

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Whole metagenome sequencing of chlorinated drinking water distribution systems

Whole metagenome sequencing of chlorinated drinking water distribution systems

There has been an explosion of research into the microorganisms present within drinking water distribution systems (DWDS). However, previous studies have focused mainly on the taxonomic composition and little is known about the actual genes composing the metagenomes of DWDS and their function or whether such information could be used for genetic profiling and monitoring processes taking place in DWDS. We use here for the first time whole metagenome shotgun sequencing to characterise microbial communities from both biofilm and bulk water samples from operational, chlorinated DWDS. Gene content analysis re- vealed habitat-specific (biofilm vs. water) differences in terms of organisms as well as gene functions, suggesting adaptation to specific environments. In addition, several resistance mechanisms were identified preferentially within biofilms, including genes associated with the prevention and repair of disinfectant radical-induced damage and antibiotic resistance. This research highlights the potential of such information to help protect drinking water quality and safety in the future following further research and wider application.
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Iron Corrosion in Occluded Water in Drinking Water Distribution Systems

Iron Corrosion in Occluded Water in Drinking Water Distribution Systems

As pipes age and corrosion continues, the pipe failure frequency tends to increase. The pitting corrosion tends to grow under the cast iron surface, leaving a porous metallic cover layer [16]. The corrosion product internal calculated porosity is 40–54% [17]. The porous core consists of solid and fluid, and the fluid in the corrosion product is completely different from the flowing water. Baylis made this discovery in 1926 and noted that the water in the interior of the tubercle had much lower pH and a higher concentration of chloride and sulfate than that of the flowing water [18]. Tuovinen et al. [19] and Nawrocki et al. [20] confirmed these facts. According to Nawrocki et al. [20], the water surrounding the corrosion products in the pipe and in the interior of the corrosion products had reductive properties and relatively high concentrations of iron, manganese and chloride. In our previous study [21], occluded water – the water that remains in corrosion products’ interiors – was acidic and had high concentrations of iron, chloride, and sulfate. Previous studies showed that once an iron pipe was installed in a DWDSs, corrosion would occur quickly during the first few years and then slow [17, 22]. After a typical product had formed, further corrosion of the corroded floor proceeded slowly [23]. However, corrosion develops on the inner surfaces of the pipes. The corrosion rate after activation is affected by the accessibility and quality of the water (e.g., pH, oxygen, alkalinity, chloride, sulfate, temperature) at the corroding metal [24]. The solution medium that the corroded floor contacts directly is occluded water, whose properties are quite different from those of flowing water. It is therefore unclear whether the corrosion rate of iron is accelerated or inhibited in the occluded water. In addition, numerous research papers have been dedicated to understanding the corrosion processes of corrosion in flowing water [25] and the pitting corrosion in simulated pore solutions [13]. However, the local corrosion in occluded water obtained from actual drinking water cast iron pipes has not been understood. Moreover, very few studies have focused on why and how natural ageing and corrosion of pipes cause water leakage. Hence, there is a vital need for research on iron corrosion in occluded water in DWDSs.
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Relating Water Quality and Age in Drinking Water Distribution Systems Using Self-Organising Maps

Relating Water Quality and Age in Drinking Water Distribution Systems Using Self-Organising Maps

Some of the factors influencing HPCs include temperature, residence time within and through the network (water age), disinfection regime and residual disinfectant, organic molecule food sources, flow velocity and patterns, and sediments [19–22]. HPC only determines a very low percentage (<1% to 10%) of the total bacteria. Since this can change between samples, it has no relation with total bacterial cells or total bacterial biomass in DWDS. From studies in the USA, it was concluded that coliform regrowth was significantly reduced in chlorinated supplies at AOC (Assimilable Organic Carbon) values below 50–100 µ g carbon/litre [23,24], indicating that AOC is much more influential than water age or temperature [25]. Some correlation was found between some types of HPC numbers in the DWDS and temperature and distance from the water treatment works (WTW) [26]. Even though the meaning of HPC is not very clear, it is widely used and much data is available.
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Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems

Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems

It was originally thought that discolouration was due to the re-suspension of sediments but Boxall et al. (2001) calculated that the size and density distributions of discolouration material do not usually allow for gravitational settling. They proposed the Prediction of Discolouration in Distribution Systems (PODDS) model under which material (organic and inorganic matter) instead ubiquitously and continually binds to the pipe wall around its circumference as cohesive layers with a single ‘shear strength’ τ c [P a]. PODDS was primarily developed to model the material erosion
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Experimental quantification of intrusion volumes due to transients in drinking water distribution systems

Experimental quantification of intrusion volumes due to transients in drinking water distribution systems

For both water and gravel external to the leak orifice it can be seen 238 that as the initial pressure head increases, the volume of intrusion into the system decreases; 239 also as the [r]

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Comparison of the microbiomes of two drinking water distribution systems—with and without residual chloramine disinfection

Comparison of the microbiomes of two drinking water distribution systems—with and without residual chloramine disinfection

Herein, we compare the results from an investigation of the microbiomes in two full-scale systems, one DWDS in the USA that maintains a chloramine residual and another in Norway that intentionally has very low or no residual disinfectant in the distributed water. Water mains and drinking water were collected from the two sys- tems. Interior surfaces of the water mains were scraped to collect biofilms and material under corrosion features (i.e., tubercles). Drinking water samples were filtered to obtain suspended cells. After DNA extraction, 16S rRNA gene amplicons from biofilms, under tubercle, and drink- ing water were sequenced to assess bacterial community composition and diversity. In addition, concentrations of total bacteria, AOB, and AOA were assessed via quanti- tative real-time polymerase chain reaction (qPCR) target- ing, respectively, bacterial 16S rRNA genes, Nitrosomonas oligotropha-like ammonia monooxygenase genes (amoA), and archaeal amoA genes. We previously reported lower quantities of Legionella spp. in the chloraminated DWDS relative to the no-residual DWDS [16]. In the present study, we provide a broader assessment of the micro- biomes in these two full-scale distribution systems.
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Characterization of Lead Leaching in Drinking Water Distribution Systems Relative to Water Age and Water Quality Parameters

Characterization of Lead Leaching in Drinking Water Distribution Systems Relative to Water Age and Water Quality Parameters

eight percent (8%) lead, according to the United States Environmental Protection Agency (EPA, 1991). The most common problem is with brass or chrome-plated brass faucets and fixtures, which can leach significant amounts of lead into the water, especially hot water. Drinking this contaminated water can contribute to children’s elevated blood-lead levels. While water is rarely the primary source of exposure to lead for children with elevated blood- lead levels, studies by Edwards et al (2004), Duti et al (2004), Triantafyllidou et al (2006), Burlingame, et al (2006) and Miranda et al (2007) have suggested that the lead leaching into drinking water has been related to the water treatment process changes, such as using ferric salts as coagulants and chloramines as secondary disinfectants, resulting in a ratio of chloride to sulfate (Triantafyllidou, et al. 2006) that is too high. Edwards, et al (2004) observed that in order to comply with Stage 1 and 2 D/DBPRs, utilities had to change some chemicals used for primary coagulation and secondary disinfection in the water treatment process. Such changes, however, may cause some utilities to be out of compliance with the Lead and Copper Rule (LCR) (EPA, 1991). For example, the conversion of free chlorine to chloramine has been linked to lead leaching and slightly increasing children’s mean blood lead levels (Edwards, et al. 2003, 2004; Miranda, et al. 2007).
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Understanding microbial ecology to improve management of drinking water distribution systems

Understanding microbial ecology to improve management of drinking water distribution systems

By not disrupting the boundary hydraulic conditions, as shown in Figure 1d, PWG coupons allow in situ monitoring of biofilm development. This facilitates detailed analyses and understanding of the development of mixed species biofilms in DWDS supplied by different water sources (Douterelo, Jackson, Solomon, & Boxall, 2016, 2017). These studies have shown higher diversity and richness in surface water supplied biofilms. The exceptionally low diversity with few dominant genera in the groundwater biofilm samples was also linked to the low-flow hydraulic conditions in the studied section. This indicates that local environmental conditions influence biofilm formation, composition, and biomass. The in situ biofilm sampling also allowed the temporal study of biofilm succession and regrowth. Independent of the characteristics of the incoming water and marked differences in hydraulic conditions between sites and over time, a core microbial community was observed in all sam- ples (Douterelo et al., 2017). This suggests that internal factors (microbial interactions) are central in shaping biofilm forma- tion. With all studies indicating the endemic and persistent presence of biofilms, future research and ultimately management strategies could consider how to manage the microbial interactions within the biofilm community. This could favor positive characteristics with the potential to exclude undesirable or pathogenic members, such as using a pro-biotic approach and avoiding chemical treatments.
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Biofilm structures (EPS and bacterial communities) in drinking water distribution systems are conditioned by hydraulics and influence discolouration

Biofilm structures (EPS and bacterial communities) in drinking water distribution systems are conditioned by hydraulics and influence discolouration

rate, peak (maximum) fl ow rate, low fl ow rate or fl ow variation. To ad- dress the aforementioned issues an internationally unique, full-scale DWDS test facility has been established at The University of Shef fi eld, providing an accurate replication of operational DWDS hydraulics using different fl ow patterns and enabling laboratory-level control of bio fi lm sampling (Deines et al., 2010; Douterelo et al., 2013; Fish et al., 2015; Sharpe, 2012). Research using this facility has begun to assess the impact of hydraulic pattern upon water quality (Sharpe, 2012) and bacterial diversity (Douterelo et al., 2013) but crucially has not in- corporated the interactions between hydraulics and the EPS. Further understanding of the hydraulics-bio fi lm (EPS and microbial communi- ty)-water quality interactions is essential so that bio fi lm formation and detachment processes can be better understood to more effectively manage and safeguard drinking water quality and hence public health. This is particularly important as infrastructure ages and DWDS must cope with increasing and changing water demand associated with pop- ulation growth and climate change.
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Characterising and Understanding the Impact of Microbial Biofilms and the Extracellular Polymeric Substance (EPS) Matrix in Drinking Water Distribution Systems

Characterising and Understanding the Impact of Microbial Biofilms and the Extracellular Polymeric Substance (EPS) Matrix in Drinking Water Distribution Systems

DWDS infrastructure presents a vast surface area-to-volume ratio (in U.K. systems this ratio has been calculated as 11 m 2 : 1 m 3 ) so a substantial area of pipe is in contact with drinking water during transportation. DWDS are composed of pipes of diverse age, material, diameter (from centimetres to metres), length and condition. Metals, plastics and cement have all been and still are used in DWDS construction (Fig. S1 † ). Internationally, many pipelines are iron domi- nated, however, polyvinyl chloride (PVC) and high or medium density polyethylene (HDPE/MDPE) are now steadily replac- ing older pipelines 5,35 and current practice (where cost effec- tive) is to re-line with epoxy based resins resulting in a sur- face with plastic-like properties (although other linings such as cement have been used historically). Pipe materials and surface condition have been found to influence biofilm growth, particularly density and community composition 7,39,79 with adhesion occurring more quickly on rougher surfaces. In- creased biofilm growth can accelerate infrastructure deteriora- tion via microbially influenced corrosion of the pipe surface, which can cause pitting, simultaneously releasing nutrients from the pipe material and forming by-products that affect surface roughness or porosity. 80 For example, iron oxidising bacteria (e.g. Shewanella, some Pseudomonas spp. and filamen- tous bacteria such as Gallionella) corrode iron and the by- products accumulate forming tubercles of Fe 3+ which increases surface roughness and promotes biofilm development. 81 This may in turn cause unaccounted energy losses, influencing DWDS hydrodynamics. Bio-corrosion can also cause water quality degradation; “ red ” , “ black ” or “ blue ” water problems can occur due to the activity of iron-, sulphate- or copper- reducing bacteria, respectively. 82
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Health implications of PAH release from coated cast iron drinking water distribution systems in The Netherlands.

Health implications of PAH release from coated cast iron drinking water distribution systems in The Netherlands.

Several polycyclic aromatic hydro carbons (PAHs) have been associated with the develop- ment of a wide range of cancers [Boffetta et al. 1997; World Health Organization (WHO) 2003]. For this reason, many countries have limits in their drinking water standards for a number of PAHs (Drinking Water Decree 2011; European Communities 1998; U.S. Environmental Protection Agency 2009). In the Netherlands, only 3 of > 1,000 routine samples collected between 2006 and 2009 exceeded drinking water quality standards for PAHs (Versteegh and Dik 2007, 2008, 2009, 2010). In spring 2009, a Dutch water com- pany received complaints about the odor and taste of drinking water after cast iron water mains were flushed (Blokker et al. 2010). After analyzing water samples, the water com- pany concluded that the complaints may have been a result of PAHs in the drinking water, which were assumed to have originated from the bitumen coating in the cast iron mains. Because PAHs are seldom found in drink- ing water, this raised questions about the frequency of increased PAH levels, the cir- cumstances in which this can occur, and the potential implica tions for human health.
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A Spark-based genetic algorithm for sensor placement in large scale drinking water distribution systems

A Spark-based genetic algorithm for sensor placement in large scale drinking water distribution systems

first step is to simulate contamination incidents and compute contamination impact by the simulator EPANET [29], which is used to perform simulation of the hydraulic and water quality behavior within pressurized pipe network. Generally speaking, this process is time-consuming because contami- nation incidents are simulated for all network junctions, one for each hour of the day. After the simulation, the results of risk are stored in an impact matrix, and then the optimiza- tion algorithm can search the optimal placement of sensors according to the impact matrix. The framework of our method is shown in Fig. 5.
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Understanding microbial ecology to improve management of drinking water distribution systems

Understanding microbial ecology to improve management of drinking water distribution systems

Full-scale DWDS experimental pipe systems (Figure 1) have transformed drinking water research by recreating realistic hydraulic, microbial, and physicochemical conditions while retaining laboratory-level control of environmental parameters and sampling regimes. Many reactors and devices to study biofilms cause significant distortion of the boundary layer and hence are not representative of pipe wall boundary layer forces and the turbulent regime that drives nutrient and material exchange to and from the boundary zone (Gomes, Simoes, & Simoes, 2014). The boundary layer is a small zone at the inter- face between a fixed surface (boundary) and the moving fluid. In this zone, the hydraulic conditions are different to those of the main bulk water flow — conditions here are laminar even when the main flow is fully rough turbulent. In this context, changes to the fixed surface (physical shape, roughness), relative size (surface to volume), and the forces driving the flow (i.e., pressure vs. rotational force) will directly impact on the conditions of shear stress and nutrient exchange that the biofilms experience. Specifically designed to address this issue, Pennine Water Group coupons (PWG, Figure 1b and c) were devel- oped to prevent disruption of the critical boundary layer hydraulics (Deines et al., 2010), while also providing a removable surface to analyze biofilms. The triple loop design of the facility allows multiple investigations of operational variables, as has been reported in several original research articles including insights into the initial stages of biofilm formation and material
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Optimal Time Step Length to Minimize Uncertainty of Zonal Water Balance Calculation in Drinking Water Distribution Systems

Optimal Time Step Length to Minimize Uncertainty of Zonal Water Balance Calculation in Drinking Water Distribution Systems

Zonal water balance analysis is capable of monitoring and quantifying water losses [1]. Common calculation time-step lengths are 30 or 60 minutes [1, 2, 9]. Minimum night flow is one of the main indicators of water loss on a distribution system [3], which can be determined as the minimum of water consumption pattern [4, 9]. The lower the time step length, the bigger the resolution of the consumption pattern. However, by decreasing the time step length, some obviously false result can occur, like negative consumption. The calculated minimum night flow depends on the resolution of the water balance (Figure 1). The difference can be as high as 60%. Minimum night flow analysis relies on zonal water balance calculations, which makes it essential to provide as accurate water balance calculations as possible. Water metering in low flow regime is problematic because as the flow rate decreases, the uncertainty of the flow metering increases [5]. Most of the pump schedule optimization methods use short-term water consumption forecast, which is sensitive to the accuracy of the historic water consumption values [11]. Therefore, the uncertainty of zonal water balance calculation affects most of the real-time pump-schedule optimization methods either.
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Active eukaryotes in drinking water distribution systems of ground and surface waterworks

Active eukaryotes in drinking water distribution systems of ground and surface waterworks

of phytoplankton. A green algae Trebouxiophyceae dom- inated winter and autumn samples whereas the activity recovery and occurrence of dinoflagellates were elevated in the samples collected in spring and summer. The quality of raw water source (surface water) may be reflected in the treated water, especially if obligate photoautotrophic microorganisms are present and the algae can survive the water treatment process [39]. Growth within the DWDS is also a feasible explanation as the green algae Trebouxiphyceae class contains non- photosynthetic species that could thrive in dark DWDS environments [50]. The high relative abundance of phyto- plankton might be also due to the reduction in the num- bers of other eukaryotic members which was observed as low species richness and less diversity in winter and au- tumn seasons. The higher relative abundance of Bilateria invertebrates (copepods, nematodes, and rotifers) ob- served in spring and summer [39] might be due to their bacterivorous properties, i.e., these benefit from the in- creased counts of heterotrophic bacteria that occurred es- pecially in summer season [21]. In DWDS of the other surface waterworks (DWDS D), the effect of season was not obvious, and thus, the source water type alone cannot explain the observed seasonal differences in DWDS C.
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Bacterial Regrowth in Drinking Water Distribution Systems:  A Comparison of Durham and Raleigh

Bacterial Regrowth in Drinking Water Distribution Systems: A Comparison of Durham and Raleigh

"adequate" residual disinfectant concentration leaving the treatment plant is not sufficient reason to disregard bacterial regrowth as a possibility for the following reasons: ([r]

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