Eaux_usees

Hubert Colas, BPR CSO

Dans l’optique de réaliser un développement immobilier intégrant les principes et technologies répondant au développement durable, un promoteur immobilier et une firme d’ingénierie conseil se sont alliées pour construire 117 nouvelles habitations dans la ville de Lübeck en Allemagne. Le lotissement compte présentement 35 habitations (duplex et maisons en rangée) pour un total de 111 personnes. Ce nombre d’habitants devrait atteindre 350 à la complétion du projet prévue à la fin de 2009.

Parmi plusieurs composantes environnementales clés du projet, le système d’assainissement est sans contredit le plus innovateur. Le concept s’articule autour de trois principes: la séparation à la source des eaux noires (toilettes) et des eaux grises (éviers, bain et appareils de lavage), le traitement sur le site et la valorisation des eaux noires et des matières résiduelles organiques traitées en agriculture.

Des toilettes à vacuum, nécessitant 1L par chasse, sont connectées à un système de conduites maintenu à basse pression qui acheminent les eaux noires de façon concentrée jusqu’à une station centrale. Arrivée à la station, les eaux noires sont pompées dans un mélangeur où sont aussi ajoutés les résidus alimentaires préalablement broyés. Subséquemment, le mélange est envoyé dans un pasteurisateur pour une période d’une heure à 65 oC. La matière passe ensuite par un échangeur de chaleur et se décharge dans un digesteur anaérobie fonctionnant à 37 oC. Le biogaz produit par la digestion est dirigé vers un épurateur, puis vers une cogénératrice. L’électricité produite est destinée aux composantes électriques de la salle technique et la chaleur est utilisée pour chauffer le pasteurisateur. La production énergétique journalière par habitant est chiffrée à 80 kWh, dont respectivement 25% et 50% peut être valorisée sous forme électrique et thermique. Pour sa part, le digestat, dont le poids est évalué à 1,9 tonne/pers*an, est envoyé par camion-citerne à une ferme située à proximité. Le digestat sera épandu lors de deux épandages au cours de la période de croissance céréalière conférant aux plantes la majeure partie des nutriments et l’eau dont elles ont besoin.

Évacuées par gravité dans les tuyaux de drainage, les eaux grises sont envoyées dans une fosse septique, puis dans un marais épurateur construit. Ce traitement naturel sans agent chimique respecte les normes de rejets des effluents dans le milieu naturel. La génération de boue au fond de la fosse septique est évaluée à 42L/pers*an.

Une évaluation économique comparative nous apprend que le coût d’investissement total pour l’instauration de ce nouveau système d’assainissement est 40% supérieur au système conventionnel, mais que le coût d’opération/maintenance annuel représente une réduction de 20%. Après avoir rencontré quelques problèmes de fonctionnement dus essentiellement à un usage non approprié de la toilette (dépôt d’objets non prescrits), les habitants se sont dits très satisfaits du système (et de la toilette) lors d’un sondage.

À l’heure actuelle, les installations de traitement et de valorisation des eaux noires ne sont pas en service. Elles le seront lorsque le nombre d’habitants dépassera 200.

Charles Thibodeau, École de technologie supérieure

With the trend towards Water Sensitive Urban Design, there has been increased interest in using stormwater infiltration as a source control solution. There have been concerns about how to minimise the environmental risks associated with infiltrating stormwater. There are currently a range of different infiltration system designs (e.g swales, filtration pits) which have been developed and use filtration media to treat stormwater runoff. Traditionally these systems have been designed around being hydraulically effective and have used un-reactive media such as sand. Stormwater treatment within subsurface filtration media has occurred primarily through a physical process of filtering out contaminants. The grainsize distribution of the filtration media was the critical factor in the design and effectiveness of these systems.

While these inert media have proven to be effective in removing stormwater contaminants that are particulate-bound they have not been as effective at removing dissolved constituents. Reactive filtration media can be more effective through providing physical filtration as well as sorption, precipitation and microbial utilisation of contaminants. Reactive media which have been trialled with stormwater include activated carbon, zeolite, diatomaceous earth, manganese and iron oxide coated sand and carbon based media such as peat and compost. There are also proprietary blends of engineered filtration media. These various media can be used to enhance microbial activity within the filter as well as increase the removal efficiency for metals, bacteria, nutrients and hydrocarbons from stormwater.

To improve the understanding about the behaviour of reactive filtration media, laboratory based studies were undertaken. Synthetic stormwater was reacted with selected filtration media and proprietary blends of media. The results showed that there were significant differences in the performance of various media in-terms of their ability to treat the stormwater.

The results showed that higher levels of treatment within stormwater infiltration systems can be achieved through using reactive filtration media. These types of media are needed if the impacts of stormwater upon the receiving waters are to be minimised.

Eric Love, Centre For Organic & Resource Enterprises

Au cours des deux dernières décennies, le mode de vie des familles a subi d'importants changements. Les gens voyagent plus, mangent plus fréquemment au restaurant, et dans de nombreuses familles les deux parents travaillent à l’extérieur de la maison. En 1970, selon les données de Statistique Canada, les deux parents de 31 % des familles canadiennes travaillaient à l’extérieur de la maison. En 1990, ce pourcentage a grimpé jusqu'à dépasser les 70 %. L’augmentation du taux de divorce a également eu des conséquences sur l’occupation des maisons. L’occupation de la maison d’une famille reconstituée peut varier d’une semaine à l’autre en raison de facteurs comme la garde partagée.

Ces transformations du mode de vie des familles ont toutes une influence sur le débit d'eaux usées provenant des demeures qui ne sont pas desservies par un réseau d’assainissement collectif. Aujourd'hui, on observe des débits intermittents et de pointe non pas uniquement dans les demeures secondaires ou saisonnières, mais également de plus en plus dans les résidences principales.

Les protocoles d’essais actuellement utilisés pour la certification des technologies (NSF 40, BNQ 3680-910, et EN 12566-3 en Europe) comprennent des essais en période de stress, mais ces derniers ne sont pas représentatifs des nouvelles contraintes (débit intermittent, surcharge) associées aux transformations du mode de vie des familles. Par exemple, le protocole NSF élaboré au cours des années 70, ne prévoit aucun essai en conditions de surcharge ou de fonctionnement à faible régime et une seule des 26 semaines d’essais est réalisée en simulant les conditions de parents au travail (alimentation et matin et le soir seulement), alors que ce mode de vie correspond maintenant à plus de 70% des situations.

Afin de soumettre les technologies de traitement des eaux usées à des essais qui traduisent mieux les nouvelles contraintes qu’imposent le modes de vie actuel, les protocoles doivent évoluer pour s’assurer que l’évaluation des technologies réalisée sur une courte période soit représentative des performances à long terme en conditions réelles d’utilisation. Cette évolution s’est amorcée au cours des 2 dernières années. Tout d’abord, le groupe international Véolia Eau a élaboré en 2006 un nouveau protocole d’essais visant à comparer et à évaluer huit technologies de traitement différentes à partir de la plateforme d'essais du Centre Scientifique et Technique du Bâtiment (CSTB) de Nantes, en France.

Également, les travaux entrepris en mars 2007 par le BNQ pour l’élaboration d’une norme canadienne de certification des technologies (CAN/BNQ Norme D 3680-600) ont pris en compte des éléments associés au nouveau mode de vie.

La conférence présentera une revue des différentes normes, des performances observées en situations réelles et des évolutions requises des protocoles pour que les technologies certifiées puissent assurer la protection de l’environnement et des ressources en eau en toutes conditions d’application.

Roger Lacasse, PremierTech Environnement

Marc-André Desjardins, AXOR Experts-Conseils

Edith Laflamme, Paramètre incorrect: fieldId

Le contexte actuel de l’industrie du traitement des eaux usées au Québec et en Amérique du Nord force celle-ci à reconsidérer la quantité de matières produites par les usines de traitement biologique. En effet, l’accroissement des coûts d’enfouissement des boues en excès a fait augmenter significativement les coûts d’exploitation. Par exemple, la proportion du budget d’opération de l’usine de traitement de la Régie d’Assainissement des Eaux du Bassin La Prairie (RAEBL) dédiée à la disposition des boues a plus que doublé en un an à cause entre autre de la nouvelle taxe à l’élimination. De plus, d’autres augmentations peuvent être envisagées étant donné que l’article 5.6.8 du Plan de gestion des matières résiduelles du gouvernement du Québec laisse anticiper un risque d’augmentation des frais incitatifs à la valorisation. Il est donc nécessaire de considérer de nouvelles technologies pour réduire la quantité de boues biologiques produite par les systèmes de traitement des eaux usées. Parmi les technologies en cours d’essais ou de réalisation à la RAEBL, il a été proposé d’envisager l’action de l’ozone sur les boues biologiques produites.

L’ozone est l’oxydant le plus puissant produit et utilisable industriellement de façon économique.

À ce jour, les utilisations en sont nombreuses :
%% - en traitement d’eau potable pour la désinfection, l’oxydation des matières organiques, la déstabilisation des particules colloïdales et la précipitation de métaux comme le fer et le manganèse;
- en traitement des eaux usées municipales et industrielles pour l’abattement de la DCO non biodégradable et sa transformation en DBO, pour la désinfection et l’élimination des micropolluants comme les perturbateurs endocriniens et les poisons pour la faune aquatique, et
- pour des procédés industriels comme le blanchiment de la cellulose et du kaolin et certaines synthèses organiques.

On connaît à ce jour trois (3) modes d’action de l’ozone sur les boues biologiques des usines de traitement des eaux usées secondaires ayant été testés en Europe:
- L’action sur les boues activées en excès en amont de la chaîne de traitement des boues;
- L’action sur les boues activées au niveau de l’aération décantation;
- L’action sur les boues de digestion anaérobie.

Dans le cas de la RAEBL, plusieurs projets sont en cours pour la réduction des boues. Le projet d’ozonation vise à maximiser la réduction des boues au niveau de l’aération décantation par :
- La réduction de la quantité de boues en excès dans le bassin;
- La réduction des coûts de disposition;
- L’amélioration de la décantation des boues activées;
- L’amélioration de la déshydratation des boues dans les filtres à bandes;
- La diminution de la quantité nécessaire de produits de conditionnement des boues.

D’autres gains peuvent être surveillés comme :
- L’oxydation de l’azote et la possibilité d’une nitrification additionnelle;
- L’oxydation et l’élimination des micropolluants empoisonnant la faune aquatique;
- L’action sur la toxicité de l’eau;
- La transformation de la DCO dure résiduelle en DBO;
- etc.

Le potentiel de réduction des boues activées basé sur des vérifications sur des essais à l’échelle réelle en Europe suggère une réduction d’au moins 40% de la matière en excès.

Malgré les promesses intéressantes du procédé d’ozonation des boues, il est parfois difficile d’établir le potentiel de réduction de la production de boues biologiques en excès. Cette analyse doit tenir compte de la particularité de chaque usine et la nature de son affluent. C’est le cas pour l’usine de traitement de la RAEBL qui reçoit plus de 60% de charges organiques de nature industrielle dont une partie importante contient déjà des boues digérées par un digesteur anaérobie et une autre partie contenant l’effluent d’une usine de pâte et papier.

L’usine de la RAEBL produit environ 1.25 kg-TSS par kg-DBO5 entrant dans le plan de traitement, bien que le ratio observe plus fréquemment est approximativement 0.5 kg-TSS par kg-DBO5. Ce ratio plus élevé fut expliqué par la proportion plus élevée de l’affluent en DCO particulaire inerte (42% comparativement à 9-20% habituellement observé) et une proportion plus basse en DCO dégradable (40% comparativement à 55-65% habituellement observé). Devant ces différences majeures, il était difficile pour le vendeur du procédé de réduction de la production de boues par l’ozone de prédire la performance de son procédé.

Nous avons développé une analyse par modélisation mathématique pour répondre à ce besoin de prédiction. Pour ce faire, il était important de constater que l’ozone ne détruit pas les matières volatiles en suspension (MVES) mais il les solubilise. De plus, la DCO soluble ainsi générée est principalement biodégradable. Basé sur l’activité bactérienne, il est commun de classifier les MVES dans la liqueur mixte secondaire en trois fractions : (i) une fraction inerte (XI), (ii) une fraction de biomasse (XH et XA), et (iii) une fraction de substrat particulaire (XS). Puisque basée simplement sur l’activité bactérienne, la nature chimique des composés formant les différentes fractions est incertaine. Cela crée aussi de l’incertitude sur l’action de l’ozone. Est-ce que l’ozone solubilise seulement la biomasse ou solubilise-t-il aussi les MVES inertes? Bien que la plupart des études suggèrent une action de solubilisation par l’ozone similaire pour toutes les fractions, nous avons considéré différents scénarios tenant en compte une variation de l’efficacité de solubilisation entre les fractions des MVES. Puisque les MVES solubilisés sont utilisés pour produire de la biomasse (donc de nouveaux solides), notre analyse a démontré que pour réduire la production de boue de 40% (une performance souvent obtenue par les procédés industriels), il est nécessaire de solubiliser environ 60-70% des MVES. Pour le cas de la RAEBL, notre analyse suggère que la grande proportion des MVES inertes réduit significativement la performance de réduction du procédé par l’ozone de 40% à au plus 30-35%. En considérant l’incertitude sur l’activité de solubilisation de l’ozone, nous avons conclu à une réduction possible de 27% pour l’usine de traitement du RAEBL. Notre analyse se présente comme une approche plus conservatrice qui tient compte de la particularité des eaux de la RAEBL qui sont à plus de 60% de nature industrielle et dont la biodégradabilité est inférieure à la moyenne. Elle propose une approche systématique pour réviser les données d’opération du plan de traitement et établir de manière rationnelle le potentiel de réduction de la production de boues.

L’analyse suggère à l’usine de tenir compte de l’impact de l’ozone sur les paramètres d’opération tel que l’âge des boues et la concentration de la liqueur mixte dans les bassins.

Par exemple, elle prédit une augmentation des besoins en aération si les paramètres d’opération actuels ne sont pas modifiés. La liqueur mixte maintenue dans les bassins doit être nécessairement diminuée pour obtenir le niveau d’aération actuel. En maintenant le niveau de la liqueur mixte constant dans les bassins, ceci entrainera une augmentation de l’âge des boues et par le fait même une demande additionnelle en aération. L’analyse réalisée peut aussi prédire l’effet de l’ozone sur l’activité des bactéries nitrifiantes. Elle suggère une diminution de la proportion de biomasse nitrifiante qui est observée dans la plupart des études. Bien que cette diminution n’affecte pas la performance du plan de traitement pour ce qui est de la nitrification de l’azote ammoniacal en condition normale, elle suggère une diminution de la robustesse du traitement aux épisodes de perturbation et une difficulté d’adapter le système à des conditions plus froides.

En conclusion, différents procédés sont maintenant disponibles pour réduire la production de boues en excès par les systèmes biologiques de traitement des eaux usées. L’ozone a sans aucun doute un impact positif sur la réduction des boues ainsi que sur l’amélioration du traitement, en particulier la décantation et la réduction de la charge organique à l’effluent de l’usine. Notre analyse systématique par modélisation mathématique permet de prédire la performance en tenant compte systématiquement des données d’opération spécifiques du plan de traitement. En plus de prédire le potentiel de réduction de production des boues, notre approche permet de prédire d’autres aspects du plan de traitement et ainsi obtenir une vue globale des effets de l’installation du procédé par l’ozone. Cette approche permet d’orienter les essais pilotes à l’échelle réelle que l’usine a l’intention de réaliser.

Dominic Frigon, Université McGill

Christian Khayat, SNC-Lavalin

Gilbert Samson, SNC-Lavalin

Daniel Gagnon, Paramètre incorrect: fieldId

A comprehensive methodology has been developed for the estimation of greenhouse gas (GHG) emissions by wastewater treatment plants (WWTPs) using different designs and treatment processes. The developed methodology considers both on-site and off-site emissions and is applied to the estimation of emissions from the treatment plants of food processing industry. On-site GHG emissions are related to liquid and solid treatment processes as well as biogas and fossil fuel combustion for energy generation. Off-site GHG emissions are related to the production of electricity for plant, production and transportation of fuel and chemicals for on-site use, degradation of remaining constituents in the effluent, as well as transmission and disposal of solids.
The production of GHGs by three different wastewater treatment systems including aerobic, anaerobic and hybrid aerobic/anaerobic treatment processes were evaluated. The results show that the produced biogas covers the total energy needs of treatment plants for aeration, heating and electricity in all three systems and its recovery significantly reduce GHG emissions of the plants. The surplus energy from the produced biogas can be used for the generation of electricity and it may be sold to the power grid. This action will further decrease total GHG emissions attributed to the plant while producing additional savings. With biogas recovery, biological processes (both on-site processes and off-site degradation of carbon) account for 94%, 44%, and 38% of total GHG emissions, and material usage is responsible for 8%, 58%, and 62% of total GHG emissions from aerobic, anaerobic, and hybrid treatment systems, respectively. The developed estimation method can be used as a guide for the development of GHG reduction strategies by targeting specific processes. For example in hybrid treatment systems, the GHG reduction strategy must focus on reducing material usage in the plant or using materials with lower off-site GHG emissions.
The results of this study demonstrate that the GHG production because of material usage, off-site energy generation and off-site degradation of carbonaceous material are substantially higher than the GHG production resulting from the treatment processes in anaerobic and hybrid treatment systems. In addition, the contribution of off-site GHG emissions to total GHG emissions is much higher in anaerobic and hybrid treatment systems compared to that in the aerobic treatment system.
The combination of aerobic treatment with anaerobic solid digestion followed by the recovery and use of biogas for energy generation is recommended as the treatment system that produces lower GHG emissions compared to anaerobic and hybrid treatment systems. The recovery and use of biogas for energy generation to replace fossil fuel combustion and to satisfy the heating requirements of the plant presents a valuable GHG mitigation strategy for wastewater treatment plants of food processing industry.

Maziar Bani Shahabadi, Concordia University

Nowadays, there is an increasing interest and demand for using sensors/analyzers to monitor and control wastewater treatment plants (WWTP). A variety of sensors is available on the market with different characteristics. To test and compare control strategies model-based approaches are widely used. However, normally sensor and actuator models are not included or the models assume the sensors to be ideal (i.e. no response time and no noise). A proper use of sensor models describing their actual behavior would make the results of the simulations more realistic. The objective of this study is to analyze the influence of different kinds of sensors on controller and WWTP performance and energy consumption. The focus is on the implementation of sensor behavior into sensor models and their inclusion in WWTP models.

The BSM1 simulation platform developed by the IWA Task Group on Benchmarking Control Strategies was used. The benchmark system provides a standardized environment to run simulations in order to objectively compare control strategies by having a standardized influent, plant configuration, size and dynamics. In this case, a cascade control strategy was used to manipulate the aeration, using on-line DO and NH4 measurements. A NO3 controller manipulating the internal recycle flow rate guaranteed optimal denitrification. Different combinations of sensor models were tested, which were set up based on experimental data (according to ISO 15839, 2003), and on a set of predefined sensor classes (Rieger et al., 2003).

The comparison of the simulation results showed that process and control performance change with different sensor characteristics. It was found that the use of slow sensors (higher response time or sampling interval) increases energy costs (aeration supply and pumping energy) and effluent concentrations. For the specific control strategies tested it was observed that an increase in response time of the DO sensor had more effect on the cost than an increase in the NH4 sensor response time. The results also showed that the use of slow sensors may decrease nitrogen removal efficiency. It is therefore concluded that proper selection and use of sensors is necessary to ensure good performance of the controller and of the overall system. Using sensor models in model-based comparisons of control strategies can help making the proper selection.

Estelle Lagacé, Université Laval

SRT (solids retention time) is a fundamental parameter in the design and operation of activated sludge systems for wastewater treatment. Alternative descriptions of SRT are used in our industry, but essentially are the same thing; for example, MCRT (mean cell residence time) or ‘sludge age’. The reason for the importance of SRT perhaps is more evident if we think in terms of sludge age.
The activated sludge system is based on the growth of biomass, and microorganisms have characteristic maximum specific growth rates. For example, nitrifier organisms have relatively slow growth rates compared to heterotrophs degrading organic material. Therefore we require a longer sludge age for nitrification. If sludge age is too short then decay of nitrifiers outweighs growth, and the organisms cannot sustain themselves in the system (i.e. nitrifiers wash out).

From the definition of SRT it is evident that, as SRT increases:
• The mass of sludge wasted per day (i.e. the sludge production) decreases.
• The mass of sludge in the system increases.
Low sludge production is desirable because sludge disposal costs are significant; this favours selecting a longer SRT. However, a longer SRT implies larger bioreactor and secondary clarifier volumes, and a more costly plant to construct. When thinking of the sizing of a WWTP it is important to recognize that the mass of sludge in the system essentially is a function only of the influent load (flow and concentration of organics) and the selected SRT. The bioreactor volume is set by selecting the operating mixed liquor solids (MLSS) concentration.
The higher the MLSS, the smaller the reactor volume. However, a higher MLSS implies a higher solids loading to the secondary clarifiers, and larger clarifiers. There will be an optimal MLSS that minimizes the total cost of bioreactors and clarifiers.
The paper does not address the issue of how to select SRT. Rather, the paper considers the case where the SRT has already been specified, and addresses two questions:
• How can we reduce or minimize sludge production as this implies reduced sludge handling and disposal costs?
• How can we reduce the size of the WWTP for a given influent load and design SRT? Alternatively, if we have an existing plant with a given influent load, how can we increase the plant capacity, and by how much?
Answers to these questions are suggested when one considers the composition of the sludge in the system (and in the waste sludge produced).

Peter Dold, EnviroSim

Diana Qing Tao, BPR

Watershed management is a holistic approach to water resource and water quality management that is based on the watershed, which is water’s fundamental geographic unit. The terms “catchment” and “basin” are often used as well. Watershed management examines issues based on all water uses, inputs and withdrawals in the watershed and develops management plans and solutions to problems in an integrated fashion. It focuses as much on the uses of land as it does the inputs and withdrawals of water.

Watershed management is a centuries-old concept that has more recently developed into a new approach and terminology which focuses on quality and land use issues. Today, watershed management has technical, political and managerial implications.

- From a technical perspective, watershed management requires examination of all water uses and land uses that might impact water, all in the context of the watershed geographic unit. It also implies a rigorous scientific assessment that quantitatively links causes, actions and effects.
-From a political perspective watershed management implies wide stakeholder involvement in the entire process from goal setting, to scientific studies, to alternative evaluations, to final planning and prioritization.
- Last, from a managerial perspective, watershed management includes a range of solutions and management actions, not only control of pollutant discharges and water withdrawals but also changes in land uses and physical features in terms of and how they impact quality, quantity and uses in the water body.

Watershed management efforts globally have been quite varied and are at different levels of evolution and different focus. In Asia and Australia, watershed management is rooted mostly in managing water availability but quality issues are quickly growing. In Europe, both availability and quality have been a long concern but a focus on land sources is now evolving. In developing countries like Africa, watershed management is very resource limited and generally only focuses on small sub-watersheds. Central and Latin American countries also have resource limitations, but have found innovative ways to improve watersheds by paying for environmental services. In the United States, watershed management is the standard paradigm for water quality management but the effectiveness of these programs is mixed.

This presentation will explore the fundamentals of watershed management for stakeholder involvement and goal setting, to problem assessment and finally watershed management plans. The presentation will highlight and compare examples of how watershed management has been applied in various areas around the globe.

Paul Freedman, LimnoTech

Danielle Stephan, US EPA

Water and Energy are emerging as the two critical resources facing humanity. Water shortages are already present in various urban and agricultural watersheds in Canada and the USA and increased climatic variability will accelerate these emerging problems. At the same time non-point sources of water pollution from urban, agricultural and forested land uses are providing new challenges for drinking and wastewater treatment operations. New approaches are needed to control demand and share scarce water resources between human and environmental use. Source water protection has now been given serious considerations and innovative approaches to stormwater management are being introduced into new urban development. The shift is from directing stormwater runoff into local stream to detaining and infiltrating water into soils wherever possible. Introducing beneficial management practices in all land use activities will help protect water supplies and water quality. A shift needs to be made between blue and green water management and serious considerations need to be given to measuring the water footprints for every land use, domestic and industrial activity.

Climate change and land use intensification both occur at the same time and the combined impact on water resources is difficult to isolate. However, there is clear evidence that climate change is increasing the variability and intensity of storms, and land use change is altering the runoff, evaporation and infiltration component of the hydrological cycle. In different parts of North America this will result in earlier snowmelt and longer dry periods. Such a shift will require significant changes to the way we store and manage water resources. We also have to deal with many new emerging contaminants and higher pollution loadings in rivers.

Individuals in North America are the largest water consumers and introducing efficient demand management practices can go a long way in reducing water scarcity. More careful management of nutrients and other chemicals is also readily possible. If we make a concerted effort to adopt innovative approaches to all these problems we can significantly reduce the risk of water scarcity and water contamination and many of the effective actions will be highlighted in the presentation.

Hans Schreier, University of British Columbia

Diana Qing Tao, BPR

In light of the many global environmental challenges our world faces, now is the time to apply the tools, methods and philosophies that can make a positive difference for the future of our planet. Since Ian McHarg’s development of the weighted overlay modeling technique in his 1969 seminal text, Design with Nature, significant strides in computer technology have made the technique powerful and widely applicable to the fields of planning, design, science, and engineering. McHarg’s message of thoughtful planning and design that integrates natural systems with the built environment remains pertinent, yet many times unobserved. When integrated into the design and planning process, purposefully applied GIS modeling can extract an understanding of the structure and function of natural systems, which can help guide future decision making and restore the balance of environmental health with the human need for development and resource utilization.

This session will present an overview of a flexible GIS modeling process that has been developed and applied for a variety of projects in the Mid-West United States, ranging from area plans, stormwater green infrastructure planning, roadway alignment alternatives, and parks and greenway planning. The author will present several case studies of the applied GIS modeling process. The case studies include the development of a stormwater green infrastructure locator for Kansas City, Missouri and Omaha, Nebraska, a county-wide Environmental Sensitivity Index (ESI) aimed at helping align a future roadway and develop a parks master plan, and integration of the ESI, green infrastructure locator, and population projection modeling to develop sustainable benchmarks for an area plan within Kansas City, Missouri. The case studies will present both planning scale results from the GIS modeling and site scale design responses derived from the modeling results.

Bryce Lawrence, Patti Banks Associates

Urban watershed planning and management involves a wide range of activities that together are designed to protect public health and ecological systems. A critical aspect of urban watershed planning is to understand how a watershed will react under a variety of environmental conditions. To do so computer modelling tools have been mainstays of the water industry assisting professionals make informed decisions based on a sound technical and scientific basis. The range of models and the application of modelling tools in urban watershed vary greatly, geographically, by agency as well as by professional preference. However, the foundation of these modelling tools, whether for quantity or quality, surface or sub-surface are based on the same fundamentals. The most important question in using models is to understand the modelling objective(s) and selecting the right tool to meet these objectives. This presentation explores these questions through the selection and application process. It also looks at how new technology such as geographical information system and new low impact development approaches are becoming integral to urban watershed planning and management.

Philip Gray, XCG Consultants

Jerry Jones, Malcolm Pirnie

Louise Babineau, Ville de Québec

Christopher S. Crockett, Philadelphia Water Department

The metropolitan Atlanta area has grown substantially over the last 20 years and continues to be one of the faster growing urban areas in the country. This growth has resulted in land use changes that have accelerated stormwater problems including localized flooding and water quality and habitat degradation. In 1996, Georgia and Region IV of the US Environmental Protection Agency (EPA) lost a legal challenge regarding Total Maximum Daily Load (TMDL) development and implementation; primarily related to the continued degradation of water quality for stormwater and associated non point source pollutant loadings. As a result, Georgia was required to meet an accelerated schedule for TDML implementation.

Faced with the challenges of TMDL implementation demands and concerns for the future assimilative capacity of metro area streams, and water supply water quality and availability, Georgia created the Metropolitan North Georgia Water Planning District (District) to address the need for comprehensive stormwater and watershed management in the rapidly developing North Georgia area. A total of 16 counties in the metropolitan Atlanta area were included in the District encompassing over 6,700 square miles. There are six major river basins within the District including the Coosa/Etowah, Chattahoochee, Oconee, Ocumulgee, Flint, and Tallapoosa river basins. Specifically the watershed management plan provided recommendations for programmatic measures that should be applied across the entire District as well as watershed specific measures to address existing or anticipated watershed conditions. In addition, the watershed management plan was coordinated with the water supply and wastewater management plans that were developed concurrently.

Development of the comprehensive watershed management plan focused on leveraging existing programs, where appropriate, and identification of additional management measures required to maintain or improve water quality and aquatic habitat conditions. The overall goal was to develop a long-term program that met multiple objectives including meeting water quality standards, TMDL implementation, source water protection, and reduction in downstream flooding. To meet these goals, a change in overall philosophy was required from the traditional stormwater end of the pipe engineering approach to one that eliminates the causes by proactively preventing stormwater problems before they occur. Greater emphasis on site planning and design to better mimic the natural hydrologic regime will be needed to reduce downstream hydrologic impacts and associated non-point source pollutant loads. In addition, significant watershed restoration activities will be needed in the already developed areas to improve stream conditions to meet designed uses. This watershed management program has been in place for 5 years and despite the comprehensive strategy, the program has had only limited success due to inconsistencies in implementation of local watershed management programs.

Doug Baughman, CH2M Hill

The Boothbay Region Water District is a quasi-municipal water district serving the towns of Boothbay, Boothbay Harbor, and Southport in a peninsular area of mid-coast Maine, a region heavily dependent on tourism and subject to seasonal shifts in population density. The District’s principal water source is Adams Pond; Knickerbocker Lake is its backup supply. The watersheds of both sources are relatively small, 1.50 and 1.59 square miles respectively, and are highly prized resources. Both water bodies are located in Boothbay, but most of the District’s customers live in Boothbay Harbor. This disparity created political friction until the present district was created by consolidating the water districts that had served the two towns.

The Boothbay Region Water District operates a state-of-the-art water treatment plant that treats 2 million gallons per day. Recognizing the importance of the multiple barrier approach, the District first seeks the highest quality raw water and, in the process, reduces treatment costs. In light of rising petroleum prices, chemicals for treatment are becoming more expensive. Plant efficiency is noticeably improved with cleaner source water due to the reduced need for electricity and water treatment.

The Maine Department of Health’s Drinking Water Program completed a Source Water Assessment Program (SWAP) review and determined Adams Pond was the most threatened water supply in Maine. Armed with the SWAP report, the District cooperated with various governmental agencies to address gross non-point source pollution problems. In addition, phosphorous levels in the two water sources necessitated passage of a watershed protection ordinance subject to a town-wide vote. To aid in enforcement of both phosphorous levels and non-point source pollution problems, the District funds, through Boothbay, a dedicated code enforcement officer to educate the public and enforce proper erosion control measures under state and local regulations. The defining moment in watershed protection came during the consolidation of the East Boothbay Water District and the Boothbay Harbor Water System into the present Boothbay Region Water District. Overnight, local Selectmen and Boothbay voters chose to “buy in” to the Boothbay Region Water District, and embrace common goals for the watershed.

The regulatory effort is supplemented by public education through local environmental groups and schools, which increases awareness and support for protecting the water supply. The Knickerbocker Lake Association, composed of owners of lake front property, promotes lake protection and public awareness of sound stewardship practices.

The district has developed tools including land acquisition and forest land protection through a myriad of land acquisition and protection strategies and by forging alliances with the Boothbay Region Land Trust and other philanthropic organizations. In addition the district has initiated best management practices to protect water quality through various partnerships.

The District believes the primary factor for its success thus far is political. The community’s political will enabled watershed protection action. Originally, the District tried unsuccessfully to take a more aggressive approach with Boothbay. Education and voluntary acceptance, or “buy-in,” turned out to be more successful. The survey and SWAP were key factors in informing the public and creating political support. Now, it is “politically correct” to support water quality protection. Still, regulating land use will continue to be a political challenge.

Throughout this process of adopting a watershed-based approach to management, the Boothbay Region Water District has learned the importance of developing a source water protection plan to guide management, devoting staff to plan implementation, staying alert to local opportunities to enhance source protection, building partnerships, leveraging federal and state regulations for local purposes, and educating local citizens and officials.

Jon Ziegra, Boothbay Region Water District

Louise Babineau, Ville de Québec

This presentation highlights what the green infrastructure approach is doing for watersheds and water quality and – importantly – what it does to preserve pipe capacity, improve neighborhoods, create “marketable amenities” that mean better economic returns for those who build green infrastructure into their buildings. Design engineers now rely on these green infrastructure facilities along with pipes, and green solutions are generally considered first where pipe solutions were once the only alternatives used.

New levels of integration of grey (pipe & concrete) and green (ecoroofs, street swales, trees, etc.) solutions include using 600 green facilities concentrated in one part of Portland, and using green facilities along the length of street corridors as the backbone for school crossings, bike lanes, and surface management of storm water. This presentation will demonstrate the value of the green solutions for the natural system as well as the existing grey infrastructure, the power of using the two approaches together, and the economics supporting these decisions. The presentation will also cover examples of regulatory negotiations that have relied successfully on these integrated solutions.

Portland, Oregon, USA is like many cities that combine storm water in sewer pipes. Storms cause peak flows in those pipes, and Portland was ordered to build a pipe system big enough to hold the peak flows so there would not be overflows to the Willamette River. Portland is complying with the order but asked years ago for it to be delayed in favor of major investments in “green infrastructure” instead. The request was denied, but Portland has nonetheless made terrific advances integrating its green and grey infrastructure and is benefitting from that management approach.

Mary Wahl, Paramètre incorrect: fieldId

Christopher S. Crockett, Philadelphia Water Department

How can water management become more sustainable through the planning and design of urban development projects? Several recent projects highlight the potential to manage stormwater with a very high degree of water quality treatment, beneficial reuse, energy savings, and even flood protection as a result. The best solutions go beyond mere compliance with stormwater regulations, and enter the realm of embracing environmental sustainability on the site scale. Low impact development techniques often include raingardens and biofiltration swales, as well as more mechanized systems for water harvesting, all falling into the category of green infrastructure for water management. Often the true benefits result from synergies between elements. For example, above and beyond the eye appeal and runoff reduction of vegetated roof top technologies, detailed analysis consistently demonstrates that green roofs are a smart choice to save money while delivering improved water quality, air quality, energy savings, and public enjoyment. Ms. Goldsmith will explore the topic of green infrastructure case studies outlining features, benefits, and anecdotes affecting decision-making; computational models for stormwater management functions and life-cycle cost/benefit analysis of green infrastructure; and issues affecting regulatory acceptance including tailored ordinances and incentives.

Wendi Goldsmith, Bioengineering Group

Robert Hausler, École de technologie supérieure

Sylvie Baig, Degrémont

Sylvie Baig, Degrémont

Pierre-André Liechti, Ozone Knowhow

a. Ozone, bienfaits et dangers, ou le bon et le mauvais ozone
o Les propriétés physiques de l’ozone
o La toxicité de l’ozone
o L’ozone naturel est essentiel à la vie, l’ozone atmosphérique
o Le bon et le mauvais ozone

b. Actions de l’ozone en bref
o L’oxydant disponible le plus puissant
o Chimie de l’ozone en phase liquide et gazeuse
o Réactivité de l’ozone avec les composés inorganiques, organiques et les microorganismes
o La complémentarité de l’ozone avec les autres oxydants
o Les procédés AOP d’oxydation avancée

c. Rôle de l’ozone dans la gestion du risque sanitaire et environnemental
o Approche et évaluation du risque sanitaire
o Ozone et risque sanitaire dans le cycle de l’eau
o Application du modèle d’évaluation
o Contexte réglementaire
o Efficacité des traitements

a. Filières de mise en œuvre
o Filière générale
o Hydraulique d’un réacteur
o Colonnes à bulles, mélangeur statique, hydro-injecteur
o Exemple de réduction des boues biologiques

b. Ingénierie de l’ozone
o Génération de l’ozone
o Conception des contacteurs d’ozone
o Transfert de l’ozone de la phase gaz dans la phase liquide
o Hydrodynamique au sein du contacteur et réactions chimiques
o Simulation numérique par mécanique des fluides

c. Applications
o L’ozone et ses applications
o Traitement des eaux de consommation
o Traitement des eaux résiduaires
o Traitement des boues biologiques
o Lavage de gaz
o Autres applications

d. Coûts de l’ozone
o Exemple d’application en traitement d’eau potable
o Coûts spécifiques
o Influence de la température de l’eau de refroidissement

Pierre-André Liechti, Ozone Knowhow

Guy Courchesne,

Increasing industrialization and changing social behaviour is directly impacting the characteristics of the wastewater to be treated. The wastewater field is entering a new era whose treatment goals must evolve with a changing society. Toxicity levels, pharmaceutical and chemical residues caused by behaviour changes are altering the aquatic ecosystems. Governmental policies and social preoccupations are moving towards implementing treatments that not only reduce the quantity of coliforms, but also address the new generation of contaminants found in the wastewater. In this research, in collaboration with different organisations (Environment Canada, INRS-Institut Armand Frappier and École de technologie supérieure), the effect of using ozone to treat wastewater containing toxicity and microorganisms was examined.

In this study the contaminants investigated were toxicity, bacteria (thermotolerant coliforms and enterococci) as well as the effects of ozone treatment on pharmaceutical residues, surface active agents and nonyphenols. The type of system used for this study was ozone bubble columns supplied by CRM Inc. The system contained multiple ozone detectors (IN USA, INC) of high and low concentrations that enabled to measure the ozone residue at the exit of each column as well as in the water. The ozone generator used, which operates on oxygen, was the OZAT CFS 1A model manufactured by Ozonia. The ozone concentrations varied between 12 mg O3/L to 18 mg O3/L. The effects of ozone treatment on the toxicity level were evaluated using the luminotox procedure. The reduction of pharmaceutical and personal care products were analyzed using the gas phase chromatography system Trace GC Ultra coupled with a Polaris Q mass spectrometry.

The results demonstrated that the toxicity of the wastewater was decreased by approximately 10% to 15% when the wastewater was treated with ozone concentrations ranging from 12 mg O3/L to 18 mg O3/L. Within these ranges, a removal rate in the order of log 4 was achieved for the thermotolerant coliforms as well as a removal rate of log 3 for the enterococci present in the wastewater. Over 85% of the major pharmaceutical and personal care products found in the wastewater were reduced when the wastewater was treated with an ozone concentration of approximately 18 mg O3/L. On average, within this range, the wastewater treated with ozone had 40% less surface active agents and 80% less nonylphenols and its ethoxylates. Moreover, treating wastewater with ozone at low concentrations effectively transforms the wastewater into a lucid liquid and improves its odour.

The results suggest that ozone is a technology capable of treating simultaneously the multi contaminants found in today’s wastewater and can be considered as an effective solution to the issues now being faced by numerous wastewater plants.

Gisella Gesuale, STEPPE-ETS

Robert Hausler, École de technologie supérieure

1) Les produits pharmaceutiques et de soins personnels (PPSP), les composés perturbateurs du système endocrinien (CPSE) et les pesticides sont des contaminants détectés couramment à l’échelle mondiale en eau de surface. La structure chimique complexe de ces composés et le risque potentiel pour la santé humaine via la consommation d’eau potable suscitent un intérêt croissant. Le sujet principal de la présentation est l’utilisation de l’ozone pour l’élimination de certains de ces composés. L’objectif est d’évaluer à l’échelle laboratoire les cinétiques d’oxydation en eaux naturelles et ultrapures, et de vérifier la concordance des résultats par rapport à des données d’échantillonnage obtenues en station de purification. 2) De plus, le développement d’une méthode de détection des radicaux libres (OH•) permet de prédire la performance du procédé d’ozonation, et permet à ce titre d’être un outil proactif. 3) Par ailleurs, dans le domaine de la désinfection, des travaux sont réalisés afin de vérifier la performance de l’ozonation (c’est-à-dire la dose délivrée) à l’aide d’une technique biodosimétrique. Le contrôle réglementaire de la désinfection est obtenu en Amérique du Nord selon le concept du CT10. Or, les données ont montré que la dose effective était supérieure au CT10, ce qui suggère une révision des critères de conception des procédés de désinfection. 4) Enfin, des essais de traitabilité sont réalisés fréquemment pour des municipalités et des firmes d’ingénierie, qui exploitent des sources d’eau variées. Les données de concentrations de sous-produits de désinfection (THM, AHA) et de CODB, obtenues depuis plusieurs années, seront rapidement présentées. Ces résultats sont très utiles pour prédire la performance de l’ozonation selon la qualité de la ressource et en fonction du point d’application de l’oxydant (pré, inter ou post-ozonation).

L’usage de l’ozo-floculation au cours du traitement conventionnel et l’expertise en filtration sur charbon actif biologique (CAB) ne seront que brièvement cités. La transformation des filtres granulaires en filtres granulaires au charbon actif biologique (CAB), qui comporte une étape intermédiaire d’ozonation, offre une solution économiquement compétitive pour répondre à la problématique des goûts et odeurs, des toxines algales et des composés xénobiotiques. Puisque la filtration biologique présente certaines limites, le développement d’un bioréacteur membranaire (procédé mixte adsorption/biodégradation à base de charbon activé) et l’impact de l’ozone sur le procédé sont analysés.

Il est à noter que les résultats expérimentaux sont validés à l’échelle réelle à l’aide d’unités mobiles semi-industrielles, uniques au Canada.

Romain Broséus, École Polytechnique de Montréal

Treatment concepts for drinking water supply are often limited by their potential to remove emerging contaminants. The potential contamination of different water sources, e.g. river water, bank filtrate, lake water or ground water by micro pollutants is known and is under investigation by several programs.
Future treatment concepts need to be able to remove preferably all of the new discussed micro pollutants. Therefore the right multi barrier approach is required. Advanced oxidation is one option to upgrade treatment processes. Consulting engineers and potential end users are in need of a cost-effective solution to treat contaminants of concern. As the concern about emerging contaminants grows, it is only a matter of time till more and more of these contaminants are regulated.

Ozone treatment and ultraviolet (UV) irradiation are well known as single treatment steps for oxidation or disinfection purposes. The combination of ozone and UV-radiation on one hand or ozone and hydrogen peroxide on the other hand results in a more powerful process. These combined processes are able to reduce many of the investigated micro pollutants efficiently and in accordance with the authority’s regulations.

A mobile pilot unit was designed to test on-site the different combined oxidation processes based on ozone, UV and hydrogen peroxide. Pilot trials were conducted with different types of water and different contaminants. One groundwater studied was contaminated by
1,4 Dioxan and Trichlorethen and a tested bank filtrate was polluted by Atrazin, Isoproturon, Carbamazepin, Diclofenac, Ibuprofen and MTBE.

Different oxidation processes (ozone, UV, UV+H2O2, ozone+UV and ozone+H2O2) were tested to identify the advantages and disadvantages of different oxidation barriers.

All tested AOP´s are able to treat the investigated substances. Depending on the water matrix and the mix of substances a single AOP may have advantages. In general, the combination ozone+H2O2 is a more energy efficient process compared to UV+H2O2. MTBE, 1,4 Dioxan and TCE is best removed by ozone+H2O2 . More photo sensitive molecules like NDMA and Iodine containing molecules are better treated by UV+H2O2. The bromate formation by using ozone+H2O2 could be limited to stay below 3 µg/L.

Achim Ried, (IOA-EA3G, IWA-AOP) ITT-Wedeco