Élaboration et validation d’un modèle de prévision des teneurs en plomb dans l’eau potable municipale

Jose Herrera, professeur agrégé, Université Western, 2012 - 2014
Enjeu

Le plomb dissout dans l’eau potable est un problème majeur de santé publique pour les collectivités canadiennes qui sont encore desservies par des conduites en plomb. C’est principalement lorsque des incrustations de corrosion à l’intérieur des tuyaux en plomb deviennent instables que du plomb se retrouve dissout dans l’eau potable. La perturbation mécanique des incrustations contenant du plomb, due à des variations dans le débit d’eau, et la dissolution galvanique sont également des facteurs qui contribuent à la présence de plomb dans l’eau (la dissolution galvanique se produit lorsqu’il y a plus d’un matériau utilisé dans la construction d’une conduite; des métaux différents ont différents potentiels d’électrode, ce qui fait qu’ils se dissolvent à des taux différents). La dissolution du plomb dans l’eau potable due à ces processus donne éventuellement lieu à des concentrations de plomb supérieures aux limites règlementaires. 

Les municipalités doivent avoir des stratégies d’atténuation réalisables pour contrôler la libération de plomb dissout dans l’eau potable. De ce fait, il leur faut bien comprendre les interrelations de la chimie de l’eau à la source d’approvisionnement, les paramètres de qualité de l’eau traitée, les options de traitement et les réactions chimiques qui se produisent au sein de l’infrastructure de distribution de l’eau.

Ce projet, sous la direction de Jose Herrera, examine les interrelations de la chimie de l’eau à la source d’approvisionnement, les paramètres de qualité de l’eau traitée, les options de traitement et les réactions chimiques qui se produisent au sein de l’infrastructure de distribution de l’eau et qui causent la déstabilisation des incrustations de corrosion. En outre, l’équipe de recherche élaborera un modèle numérique pour prédire la dissolution de plomb dans les systèmes de distribution d’eau.

Projet

This research program assesses the variables that control lead corrosion in water systems and will apply understanding gained to develop a model to predict lead dissolution in water distribution systems. To do this, field data will be collected by partner Canadian municipalities and from pipe loop systems with lead plumbing obtained from partner communities. This will involve collecting and characterizing solid lead corrosion scales from lead pipes in communities with different water quality characteristics and conducting continuous pipe loop dissolution experiments. Data will also be collected from home studies in the distribution systems of these municipalities. This data will be used to develop and validate the numerical lead dissolution model developed by the project team.  If possible, data related to the impact of other variables on lead dissolution collected by other researchers (not involved with this project) will be incorporated/used to validate the model. 

Researchers anticipate that when this project is complete, the model will also be capable of simulating long-term solid phase transformations in the corrosion scale due to changes in the water chemistry. This understanding is essential not only from a strictly scientific point of view, but also for drinking water operators as it is needed to evaluate the long-term effectiveness of a corrosion control strategy.

Produits

Anticipated outputs include:

  • Modeling tool developed which will be available and widely disseminated to water quality managers, water supply operators, and other decision makers in Canada interested in the research outcomes.
  • To facilitate the use and application of the numercial model, a simple, user-friendly Windows® interface tool will be developed to enable the numerical lead dissolution model to be used by non-expert modellers (e.g., municipal water engineers).

This tool will enable users to specify their exisitng or anticipated water/solid scale properties and thus, ensure that the water entering their distribution system has the characteristics required to avoid destabilization of inner pipe lead scale. 

Résultats

Anticipated outcomes include:

  • The proposed numercial model will be employed as a decision-support and sensitivity analysis tool by municipalities to analyze the effectiveness of their water treatment system.
  • Informed investments: The use of the modeling tool by Ontario municipalities will result in a significant long-term reduction of analytical expenditures.  It is expected to reduce the number of samples required to test for lead levels by 50%.
  • Assist decision-making: The research findings will assist Canadian municipalities with the prioritization of replacement of the lead pipe infrastructure.
  • The results of this project will expand the successful research of a previous study with City of London that evaluated the surface structure and composition of the lead corrosion scale present in London’s drinking water pipes, which enabled the City of London engineers to develop a strategy to modify water quality parameters to minimize lead corrosion.
  • Additionally, this research has helped establish strong partnerships with Ottawa and Toronto municipalities.  Researchers are currently exploring additional areas of common interest for future project collaboration with all partners.

Lead in drinking water

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Équipe de Recherche et Partenaires:

Équipe de Recherche

Jose Herrera, Associate Professor, Western University

Clare Robinson, Associate Proffessor, Western University
Onita Basu, Professor, Carelton University
John Braam, Water Director and City Engineer, City of London
Dan Huggins, Water Quality Manager, City of London
Ian Douglas, Adjunct Professor, University of Toronto, Water Quality Engineer and Plant Manager, City of Ottawa
Andy Campbell, Water Quality Technologist, City of Ottawa
Quirien Muylwyk, Regional (Canada) Technology Manager, CH2M HILL; Vice Chair,AWWA Water Quality Division
Susan Atlin, Senior Engineer, Operations Efficiency Group of Toronto Water
David Scott, Technologist, Toronto Water’s Operations Efficiency Group
Carolyn de Groot, Process Engineer, Huron and Elgin Regional Water Supply Division and Research Liaison, University of Toronto; University of Waterloo NSERC Water Chairs and Western University

Partenaires

CH2M HILL,
City of Ottawa,
City of London,
City of Toronto

RESEARCH SUMMARY
(5-page report)

CWN EN Herrera 2016