Redox gradients in distribution systems influence water quality, corrosion, and microbial ecology

Masters, Sheldon; Wang, Hong; Pruden, Amy; Edwards, Marc

doi:10.1016/j.watres.2014.09.048

Cited by 49 publications

(23 citation statements)

References 51 publications

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“…As previously reported, 23,31 the SDSs successfully generated a matrix of waters with a wide range of physiochemical properties (Supporting Informaiton Table S2), reflecting trends known to occur in practice as water is transported through distribution systems and before it enters buildings. Briefly, disinfectant concentration and DO decreased with increasing water age in all SDSs, while TOC increased (P < 0.05).…”

Section: ■ Resultssupporting

confidence: 62%

“…One atypical trend compared to practical field experience was faster chloramine decay relative to chlorine (Supporting Information Table S2), which was a result of nitrification evidenced by increased nitrite level and presence of nitrifiers in chloraminated SDSs. 23,31 Variation of Microbial Numbers in SWH Influent and Effluent. Although not a direct measure of viability, numbers of gene markers in and out of SWHs with time were considered as indicators of regrowth or attenuation in the SWHs throughout the study.…”

Section: ■ Resultsmentioning

confidence: 99%

“…6 The objective of this study was to investigate the influence of water quality from the main distribution system on the occurrence and persistence of Legionella spp., NTM, P. aeruginosa and two genera of host amoebae (Acanthamoeba spp., Vermamoeba vermiformis) in household water heaters. Simulated distribution systems (SDSs) with different disinfectants (chlorine, chloramines) and pipe materials (cement, iron, PVC) were operated to create influent with water age of 2.3, 3.6, and 5.7 days 23,30,31 to simulated household water heaters (SWHs). The SWHs were held at a constant temperature (37°C) with infrequent water changes (1−3× per week), to track microbial changes during "worst case" stagnation events typical of weekends/holidays for premise plumbing and isolate the variables represented by the SDS water.…”

Section: ■ Introductionmentioning

confidence: 99%

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Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

Wang

Masters

Falkinham

et al. 2015

Environ. Sci. Technol.

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Illustrative distribution system operation and management practices shaped the occurrence and persistence of Legionella spp., nontuberculous mycobacteria (NTM), Pseudomonas aeruginosa, and two amoebae host (Acanthamoeba spp., Vermamoeba vermiformis) gene markers in the effluent of standardized simulated household water heaters (SWHs). The interplay between disinfectant type (chlorine or chloramine), water age (2.3-5.7 days) and materials (polyvinyl chloride (PVC), cement or iron) in upstream simulated distribution systems (SDSs) profoundly influenced levels of pathogen gene markers in corresponding SWH bulk waters. For example, Legionella spp. were 3-4 log higher in SWHs receiving water from chloraminated vs chlorinated SDSs, because of disinfectant decay from nitrification. By contrast, SWHs fed with chlorinated PVC SDS water not only harbored the lowest levels of all pathogen markers, but effluent from the chlorinated SWHs were even lower than influent levels in several instances (e.g., 2 log less Legionella spp. and NTM for PVC and 3-5 log less P. aeruginosa for cement). However, pathogen gene marker influent levels correlated positively to effluent levels in the SWHs (P < 0.05). Likewise, microbial community structures were similar between SWHs and the corresponding SDS feed waters. This study highlights the importance and challenges of distribution system management/operation to help control opportunistic pathogens.

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Section: ■ Resultssupporting

confidence: 62%

Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

Wang

Masters

Falkinham

et al. 2015

Environ. Sci. Technol.

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“…It is well known that disinfection can speed up corrosion and cause plumbing leaks, even though contradictory results are reported in the literature concerning the impact of disinfection on corrosion (7)(8)(9)(10). To complete the study, we studied the appearance of a favorable environment for corrosion within the water networks according to the disinfection methods applied.…”

Section: Discussionmentioning

confidence: 99%

“…A range of physical and chemical disinfection methods have been proposed, but to date, the most effective procedures for controlling contamination have not been defined (6). Moreover, their impacts on pipe deterioration/corrosion have not been documented extensively and are studied mainly in model water distribution systems (7)(8)(9)(10).…”

mentioning

confidence: 99%

Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures

Marchesi

Mansi

Marcelloni

et al. 2016

Appl Environ Microbiol

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bPhysical and chemical disinfection methods have been proposed with the aim of controlling Legionella water contamination. To date, the most effective procedures for reducing bacterial contamination have not yet been defined. The aim of this study was to assess the long-term effectiveness of various disinfection procedures in order to reduce both culturable and nonculturable (NC) legionellae in different hospital water networks treated with heat, chlorine dioxide, monochloramine, and hydrogen peroxide. The temperature levels and biocide concentrations that proved to give reliable results were analyzed. In order to study the possible effects on the water pipes, we verified the extent of corrosion on experimental coupons after applying each method for 6 months. The percentage of positive points was at its lowest after treatment with monochloramine, followed by chlorine dioxide, hydrogen peroxide, and hyperthermia. Different selections of Legionella spp. were observed, as networks treated with chlorinebased disinfectants were contaminated mainly by Legionella pneumophila serogroup 1, hyperthermia was associated with serogroups 2 to 14, and hydrogen peroxide treatment was associated mainly with non-pneumophila species. NC cells were detected only in heat-treated waters, and also when the temperature was approximately 60°C. The corrosion rates of the coupons were within a satisfactory limit for water networks, but the morphologies differed. We confirm here that chemical disinfection controls Legionella colonization more effectively than hyperthermia does. Monochloramine was the most effective treatment, while hydrogen peroxide may be a promising alternative to chlorine-based disinfectants due to its ability to select for other, less virulent or nonpathogenic species.

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Impacts of Water Quality on the Spatiotemporal Susceptibility of Water Distribution Systems

Mortula

Ali

Sadiq

et al. 2019

CLEAN Soil Air Water

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Maintaining water quality in distribution systems is crucial for ensuring safety of water supply. The distribution infrastructure is typically buried underground and it is often difficult to assess the condition of the system. In case of breakage of underground pipe network, external agents, like microorganisms may ingress into the distribution system which then react with residual disinfectant (chlorine) and result in faster decay. Understanding the chlorine decay is critical to ensuring the acceptable condition of the water distribution infrastructure. The objective of this study is to assess the spatiotemporal susceptibility of a water distribution network based on water quality variations. GIS based residual chlorine decay, temperature, and Langelier saturation index (LSI) profiles for the entire water distribution network are created using inverse distance weighting technique. Hotspot analysis is conducted to identify the vulnerable sections of the city's water distribution network based on residual chlorine. Spatial variations can not identify a consistent pattern of decay throughout the distribution system. However, some sections of the old part (North western) of the city show low residual chlorine levels compared to other locations. LSI values are negative in some source waters, leading to potential degradation of the distribution pipes. Temporal variations indicate that residual chlorine levels drop late summer and early fall. However, hotspot analysis identifies that some of the old part of Sharjah has consistently low residual chlorine levels, indicating considerable degradation of the distribution pipes.

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Redox gradients in distribution systems influence water quality, corrosion, and microbial ecology

Cited by 49 publications

References 51 publications

Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures

Impacts of Water Quality on the Spatiotemporal Susceptibility of Water Distribution Systems

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