Are Secondary Disinfectants Performing as Intended?

Speight, Vanessa; Rubinato, Matteo; Rosario‐Ortiz, Fernando L.

doi:10.1002/awwa.1394

Cited by 2 publications

(3 citation statements)

References 11 publications

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“…This is commonly driven by disinfection benefits being outweighed by risks associated with potentially carcinogenic DBPs, which are of growing concern with increasing detection/identification 6,8 . An article by Speight et al 9 . calculated the contact times required to inactivate various microorganisms (assuming 0.5 mgL −1 chlorine, pH7 and 5°C), concluding that the disinfectant contact times within DWDS are likely ineffective in their inactivation.…”

Section: Introductionmentioning

confidence: 99%

“…These sub-lethal doses of disinfectant can then exert a selective pressure and various research studies have shown that the presence, type and concentration of disinfection impacts the planktonic bacterial composition of drinking water, enriching or decreasing certain functional genes or bacterial taxa 10 – 12 . Similarly, comparison of regulatory water sample compliance illustrated that the USA, which uses chlorine residual disinfection, had 10 times more total coliform failures than the Netherlands, which does not use a disinfection residual 9 , this is after adjusting for population, although there are other differences beside disinfection between the systems (e.g. infrastructure age, organic concentrations).…”

Section: Introductionmentioning

confidence: 99%

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Uncharted waters: the unintended impacts of residual chlorine on water quality and biofilms

Fish

Reeves‐McLaren

Husband

et al. 2020

npj Biofilms Microbiomes

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Disinfection residuals in drinking water protect water quality and public heath by limiting planktonic microbial regrowth during distribution. However, we do not consider the consequences and selective pressures of such residuals on the ubiquitous biofilms that persist on the vast internal surface area of drinking water distribution systems. Using a full scale experimental facility, integrated analyses were applied to determine the physical, chemical and biological impacts of different free chlorine regimes on biofilm characteristics (composition, structure and microbiome) and water quality. Unexpectedly, higher free chlorine concentrations resulted in greater water quality degredation, observable as elevated inorganic loading and greater discolouration (a major cause of water quality complaints and a mask for other failures). High-chlorine concentrations also reduced biofilm cell concentrations but selected for a distinct biofilm bacterial community and inorganic composition, presenting unique risks. The results challenge the assumption that a measurable free chlorine residual necessarily assures drinking water safety.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Uncharted waters: the unintended impacts of residual chlorine on water quality and biofilms

Fish

Reeves‐McLaren

Husband

et al. 2020

npj Biofilms Microbiomes

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“…Temperature is an important determinant of drinking water quality as it affects the physical, chemical and biological processes occurring within the DWDS, including microbial growth and the rate of chlorine decay [21]. It has been suggested that the disinfection contact times within DWDS are insufficient to inactivate various microorganisms [32]. The sub-lethal doses can then exert a selective pressure which impacts the planktonic (free-living microorganisms in the bulk-water; [33,34]) and biofilm microbiomes and cell concentrations [35,36].…”

Section: Introductionmentioning

confidence: 99%

Impacts of temperature and hydraulic regime on discolouration and biofilm fouling in drinking water distribution systems

Fish

Sharpe²,

Biggs³

et al. 2022

PLOS Water

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Discolouration is the greatest cause of customer dissatisfaction with drinking water quality, potentially masking other failures, including microbial issues, which can impact public health and well-being. The theorised association between biofilms (complex microbial communities) and discolouration within drinking water distribution systems (DWDS) was explored, whilst studying the impact and interactions of seasonal temperature variations and hydraulic regime. Transferability of findings to operational DWDS was ensured by using a temperature controlled, full-scale distribution experimental facility. This allowed isolation of the factors of interest, with integration of physical, chemical and microbial analyses. Greater discolouration and biofilm cell accumulation was observed under warmer (summer, 16°C) temperatures compared to cooler (winter, 8°C), evidence of microbiology being an important driver in DWDS discolouration behaviour. Temperature was generally more influential upon discolouration and biofilm cell volumes than the shear stress imposed by the hydraulic regimes, which included three steady state and two varied flow patterns. However, the trends were complex, indicating interactions between the two parameters in governing microbial accumulation and discolouration. These results are important in informing sustainable management of our ageing DWDS infrastructure to deliver safe high quality drinking water. By providing new evidence that discolouration is a biofilm/microbiologically-mediated process, we can better understand the importance of targeting interventions to hotter seasons, and manipulating hydraulic conditions (which we can control), to minimise the long-term impacts of impending changing climates on water quality.

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Are Secondary Disinfectants Performing as Intended?

Cited by 2 publications

References 11 publications

Uncharted waters: the unintended impacts of residual chlorine on water quality and biofilms

Uncharted waters: the unintended impacts of residual chlorine on water quality and biofilms

Impacts of temperature and hydraulic regime on discolouration and biofilm fouling in drinking water distribution systems

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