Greater Vancouver's drinking water treatment program

Ferguson, A. M.; Neden, Douglas G.

doi:10.1139/l00-067

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…Research has concluded that microbial regrowth is highly dependent on the concentration of AOC (Assimilable Organic Carbon) and nutrients as well as temperature and pH of finished water (Lechevallier et al, 1996;van der Kooij, 1992;Miettinen et al, 1997;Liu et al, 2002;Ferguson and Neden 2001). Therefore, when microbial regrowth in a distribution system is studied, attention must be given to the quality of source water intake, seasonal temperatures, and the pH value of finished water.…”

Section: Microbial Qualitymentioning

confidence: 99%

A Review of Reliability Analysis for Water Quality in Water Distribution Systems

Huang‬‬‬‬

McBean

James

2005

JWMM

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A review of reliability research for water distribution systems demonstrates that, to date, little is currently available characterizing water quality reliability indices. The incidence of microorganism caused outbreaks of waterborne disease demonstrates a number of causes, most of which are the result of water treatment system deficiencies. However, the basis for a change in this situation is projected as a result of the increasing age of distribution system components, increasing urban populations, per capita water demands, and deterioration of water distribution infrastructure. Although there is no universal agreement on how to define, or measure, the reliability of a water distribution system, this Chapter reviews the alternatives for characterizing reliability, demonstrating some of the strengths and weaknesses, and provides areas of future research. Water Distribution System Reliability 108 conditions. This means that for a reliable water supply system, water must be (i) available on demand, (ii) delivered at a sufficient pressure for proper use, and (iii) safe in terms of quality. Although reliability of a water supply system in general is a measure of performance in terms of the three factors indicated, undesirable events/failure will occur which will cause a decline or interruption in system performance. The reliability of a water supply system can be considered under three types of failure: mechanical, hydraulic and water quality failure. Mechanical failures, also termed component failures, may, for example, be pipe breakage, pump failure, power outages, or control valve failure. Changes in demand or in pressure head may result in hydraulic failures. These failures may be due to, for example, old pipes with varying roughness, inadequacy in pipe size due to increased water demands, insufficient pumping capacity, and insufficient in-system storage capacity. Water quality failure may be defined as occurrences where the concentrations of contaminants exceed the maximum contaminant level (MCL) defined by water quality standards. The major concern for water quality failure is the adverse effect on the health of humans. Due to the importance of water supply systems for the needs of society and for industrial growth, reliability studies have become of increasing importance for water distribution systems where considerations of planning, design and operations are integrated. However, quantifying the reliability of a water supply system continues to be a major problem. For confident decision-making, a set of meaningful and appropriate reliability measures need to be defined, wherein all the measures must be computationally feasible. Reviews of the literature by Mays (1996) and Engelhardt et al. (2000) revealed that that there is no universal agreement on how to define, or measure, the reliability of a water distribution system. This Chapter reviews the alternatives for characterizing reliability, demonstrating some of the strengths and weaknesses, and provides areas of future research. 7.2 Reliability Index Altho...

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Section: Microbial Qualitymentioning

confidence: 99%

A Review of Reliability Analysis for Water Quality in Water Distribution Systems

Huang‬‬‬‬

McBean

James

2005

JWMM

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A practical guide for determining appropriate chemical dosages for direct filtration

Tchio¹,

Koudjonou²,

Desjardins³

et al. 2003

Can. J. Civ. Eng.

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The tests conducted in this study have made it possible to propose a rapid and simple laboratory method for determining the appropriate dosages of chemicals according to filtering materials effective sizes (ES), for direct filtration applications, and for adjusting the dosages according to raw water quality changes. Application of the proposed procedure requires but simple laboratory equipment: an Ives' filterability index measuring device, a filtration system operating under a constant vacuum, and 0.45 and 8 µm membrane filters. The use of 0.45 µm membrane filtration allows one to determine the best dosages for fine material with an effective size of 0.4 mm, whereas Ives' filterability index and 8 µm membrane filtration help determine the best dosage applicable to the 1.2 mm ES. The results obtained showed that for other effective sizes in the 0.4-1.2 mm range, the best dosages of alum and polymer can be estimated by linear interpolation. This laboratory procedure is a useful tool for quickly determining the best chemical dosages versus filtering media ES for a given water quality. It should be applied to raw waters with unknown characteristics prior to carrying out a more accurate full-scale validation, if necessary.Résumé : L'étude décrite dans cet article propose une procédure simple et rapide de détermination des meilleures doses de produits chimiques en filtration directe, selon le diamètre effectif du matériau filtrant (DE) et la qualité de l'eau brute à traiter. En effet, cette méthode requiert des équipements de laboratoire très simples dont un système de filtration sous vide avec deux types de papier filtre de 0,45 µm et de 8 µm et un dispositif de mesure de l'indice de filtrabilité de Ives. La filtration sur membrane de 0,45 µm s'est avérée utile pour déterminer le meilleur dosage pour un DE de 0,4 mm alors que l'indice de filtrabilité de Ives et la filtration sur 8 µm permettent de déterminer la meilleure dose pour un DE de 1,2 mm. Les résultats des essais ont montré que pour les valeurs intermédiaires de DE, les meilleures doses peuvent être déterminées par simple interpolation linéaire. Cette procédure devrait permettre de définir rapidement en laboratoire les doses appropriées de coagulants et de polymères requises pour une filière de filtration directe. Appliquée à une eau de caractéristiques inconnues, elle devrait permettre une estimation rapide de la dose de coagulant avant de procéder, si nécessaire, à des ajustements plus poussés en usine réelle.Mots clés : filtration directe, coagulation, floculation, meilleure dose, alun, diamètre effectif, indice de filtrabilité de Ives, filtration sur papier filtre.Tchio et al. 757

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Greater Vancouver's drinking water treatment program

Cited by 2 publications

References 3 publications

A Review of Reliability Analysis for Water Quality in Water Distribution Systems

A Review of Reliability Analysis for Water Quality in Water Distribution Systems

A practical guide for determining appropriate chemical dosages for direct filtration

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