Temperature Influences Discolouration risk

Blokker, Mirjam; Schaap, Peter G.

doi:10.1016/j.proeng.2015.08.887

Cited by 9 publications

(11 citation statements)

References 7 publications

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“…After the mobilisation phase, the concentration of these metals and turbidity response increased significantly at both temperatures with significant higher values for these two parameters observed after the flushing event at 24°C. These results indicate that higher temperature led to a greater material accumulation on this chlorinated DWDS, as it was observed by Blokker and Schaap (2015) in unchlorinated DWDS. This finding is in agreement with the SEM micrographs obtained from coupons, which showed a visual greater accumulation of biofilm on the surface of the coupon at 24°C.…”

Section: Discussionsupporting

confidence: 74%

“…During the growth phase, the hydraulic conditions of the system were constant following a daily pattern of LVF, explaining the expected absence of changes in turbidity and metal concentrations. After the mobilisation phase, the concentration of these metals and turbidity response increased significantly at both temperatures with significant higher values for these two parameters observed after the flushing event at 24 • C. These results indicate that higher temperature led to a greater material accumulation on this chlorinated DWDS, as it was observed by Blokker and Schaap (2015) in unchlorinated DWDS. This finding is in agreement with the SEM micrographs obtained from coupons, which showed a visual greater accumulation of biofilm on the surface of the coupon at 24 • C. Previous research, reported a link between microbial growth and temperatures; Hallam et al (2001) concluded that biofilm potential growth in chlorinated DWDS was enhanced at higher temperatures; and Ahmad et al (2020) observed higher biofilm concentrations in unchlorinated DWDS with cold recovery technologies concluding that microbial growth kinetics in biofilms were affected by temperature.…”

Section: Effect Of Temperature Rise On Water Physico-chemistry and Discolourationmentioning

confidence: 50%

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Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

et al. 2021

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Temperature variation can promote physico-chemical and microbial changes in the water transported through distribution systems and influence the dynamics of biofilms attached to pipes, thus contributing to the release of pathogens into the bulk drinking water. An experimental real-scale chlorinated DWDS was used to study the effect of increasing temperature from 16 to 24°C on specific pathogens, bacterial-fungal communities (biofilm and water samples) and determine the risk of material accumulation and mobilisation from the pipes into the bulk water. Biofilm was developed for 30 days at both temperatures in the pipe walls, and after this growth phase, a flushing was performed applying 4 gradual steps by increasing the shear stress. The fungal-bacterial community characterised by Illumina MiSeq sequencing, and specific pathogens were studied using qPCR: Mycobacterium spp., Mycobacterium avium complex, Acanthamoeba spp., Pseudomonas aeruginosa, Legionella pneumophilia, and Stenotrophomonas maltophilia. Sequencing data showed that temperature variation significantly modified the structure of biofilm microbial communities from the early stages of biofilm development. Regarding bacteria, Pseudomonas increased its relative abundance in biofilms developed at 24°C, while fungal communities showed loss of diversity and richness, and the increase in dominance of Fusarium genus. After the mobilisation phase, Pseudomonas continued being the most abundant genus at 24°C, followed by Sphingobium and Sphingomonas. For biofilm fungal communities after the mobilisation phase, Helotiales incertae sedis and Fusarium were the most abundant taxa. Results from qPCR showed a higher relative abundance of Mycobacterium spp. on day 30 and M. avium complex throughout the growth phase within the biofilms at higher temperatures. The temperature impacts were not only microbial, with physical mobilisation showing higher discolouration response and metals release due to the increased temperature. While material accumulation was accelerated by temperature, it was not preferentially to either stronger or weaker biofilm layers, as turbidity results during the flushing steps showed. This research yields new understanding on microbial challenges that chlorinated DWDS will undergo as global temperature rises, this information is needed in order to protect drinking water quality and safety while travelling through distribution systems.

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Section: Discussionsupporting

confidence: 74%

Section: Effect Of Temperature Rise On Water Physico-chemistry and Discolourationmentioning

confidence: 50%

Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

et al. 2021

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“…addition, independent studies suggest that sediment load and frequency of customer discoloration reports vary with the water temperature within the distribution pipes, as opposed to temperatures at the treatment plant (Blokker and Schaap, 2015b;Van Summeren et al, 2015). Furthermore, a cluster analysis of discoloration customer reports shows evidence that discoloration events are caused on the local level, suggesting that mechanisms in distribution pipelines rather than in transport mains critically control discoloration events (Van Rooij, 2016).…”

Section: Identifying Relevant Transport Processes From Current Undersmentioning

confidence: 99%

Modeling particle transport and discoloration risk in drinking water distribution networks

Summeren

Blokker

2017

Drink. Water Eng. Sci.

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Abstract. Discoloration of drinking water is a worldwide phenomenon caused by accumulation and subsequent remobilization of particulate matter in drinking water distribution systems (DWDSs). It contributes a substantial fraction of customer complaints to water utilities. Accurate discoloration risk predictions could improve system operation by allowing for more effective programs on cleaning and prevention actions and field measurements, but are challenged by incomplete understanding on the origins and properties of particles and a complex and not fully understood interplay of processes in distribution networks. In this paper, we assess and describe relevant hydraulic processes that govern particle transport in turbulent pipe flow, including gravitational settling, bedload transport, and particle entrainment into suspension. We assess which transport mechanisms are dominant for a range of bulk flow velocities, particle diameters, and particle mass densities, which includes common conditions for DWDSs in the Netherlands, the UK, and Australia. Our analysis shows that the theoretically predicted particle settling velocity and threshold shear stresses for incipient particle motion are in the same range as, but more variable than, previous estimates from lab experiments, field measurements, and modeling. The presented material will be used in the future development of a numerical modeling tool to determine and predict the spatial distribution of particulate material and discoloration risk in DWDSs. Our approach is aimed at understanding specific causalities and processes, which can complement data-driven approaches.

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“…Discolouration is reported to be positively correlated with temperature, such that the frequency of reported discolouration increases in the summer months [13,18]. The accumulation of material within DWDS has also been shown to be elevated at higher temperatures [19]. Water temperature is acknowledged to differ spatially (between networks and along pipes) and temporally (i.e.…”

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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Temperature Influences Discolouration risk

Cited by 9 publications

References 7 publications

Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

Modeling particle transport and discoloration risk in drinking water distribution networks

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

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