Accelerated chloramine decay and microbial growth by nitrification in premise plumbing

Zhang, Yan; Edwards, Marc

doi:10.1002/j.1551-8833.2009.tb09990.x

Cited by 70 publications

(67 citation statements)

References 30 publications

(50 reference statements)

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“…Previous studies have found an increase in nitrification in chloraminated systems, which effectively decreased monochloramine concentration [6], [31]. This chemical decay led to higher levels of Legionella , Mycobacterium spp., and P. aeruginosa at earlier water ages than in chlorinated simulated distribution systems [6].…”

Section: Discussionmentioning

confidence: 87%

Shift in the Microbial Ecology of a Hospital Hot Water System following the Introduction of an On-Site Monochloramine Disinfection System

Baron

Vikram

Duda³

et al. 2014

PLoS ONE

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Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system microbial ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the microbial ecology of a hospital’s hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing microbial ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on microbial ecology and not solely specific target microorganisms.

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Section: Discussionmentioning

confidence: 87%

Shift in the Microbial Ecology of a Hospital Hot Water System following the Introduction of an On-Site Monochloramine Disinfection System

Baron

Vikram

Duda³

et al. 2014

PLoS ONE

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“…In the present study, nitrification in chloraminated SDS resulted in much lower chloramine residuals relative to chlorine in the upstream SDSs, supporting recent studies indicating that chloramine decay is sometimes faster than chlorine decay in at least some unusual circumstances. 41 Thus, expected benefits of more persistent chloramine residuals were not observable in these SWHs and nitrification was associated with conditions conducive to regrowth.…”

Section: ■ Discussionmentioning

confidence: 96%

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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“…In the United States, increasing numbers of utilities are adopting chloramines for secondary disinfection (Seidel et al, 2005) because it is more persistent than free chlorine, it results in lower production of disinfection byproducts than free chlorine (Seidel et al, 2005), and chloramines penetrate biofilms more readily than free chlorine (LeChevallier et al, 1988). Nitrification is also believed to be common in premise plumbing systems (Zhang & Edwards, 2009) and a potential contributing cause of amplification of N. fowleri and increased human exposure. Nitrification results in accelerated decay of chloramines (and loss of residual disinfecting capacity), increased biofilm growth, and reduced capacity to inactivate microorganisms in the biofilms and suspended in the water.…”

Section: N Fowleri Management In Drinking Water Production and Distrmentioning

confidence: 99%

“…These conditions are conducive to propagation of N. fowleri because they result in reduced disinfectant residual and increased populations of cells that may be used as food. Nitrification is also believed to be common in premise plumbing systems (Zhang & Edwards, 2009) and a potential contributing cause of amplification of N. fowleri and increased human exposure.…”

Section: N Fowleri Management In Drinking Water Production and Distrmentioning

confidence: 99%

Naegleria fowleri: An emerging drinking water pathogen

2014

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Naegleria fowleri (N. fowleri) is a free‐living, trophic amoeba that is nearly ubiquitous in the environment and can be present in high numbers in warm waters. It is the causative agent of primary amoebic meningoencephalitis (PAM), a rare but particularly lethal disease with a very low survival incidence. Although N. fowleri was isolated from drinking water supplies in Australia in the 1980s, it was not considered a drinking water threat in the United States until recent cases were associated with a groundwater system in Arizona and surface water systems in Louisiana. N. fowleri in drinking water treatment and distribution systems can be managed using disinfectant concentrations typically encountered in well‐run plants although nitrification and attendant low disinfectant residuals may pose a challenge for some systems. The greatest challenge for N. fowleri control is in premise plumbing systems where conditions are largely outside the control of utilities, residuals might be low or nonexistent, and where water temperatures could be high enough to support rapid growth of the amoebae. This article reviews published studies describing the environmental occurrence, survival, pathogenicity, and disinfection of N. fowleri. In addition, this article provides information about this little known and poorly understood parasite with respect to its occurrence in the environment; how the amoeba amplifies in water systems such that it can cause infection; how N. fowleri has been successfully controlled for decades in water systems through treatment and distribution system management in Australia; and the knowledge gaps and information needed to address N. fowleri as an emerging pathogen in US water supplies.

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Accelerated chloramine decay and microbial growth by nitrification in premise plumbing

Cited by 70 publications

References 30 publications

Shift in the Microbial Ecology of a Hospital Hot Water System following the Introduction of an On-Site Monochloramine Disinfection System

Shift in the Microbial Ecology of a Hospital Hot Water System following the Introduction of an On-Site Monochloramine Disinfection System

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

Naegleria fowleri: An emerging drinking water pathogen

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