Eau_potable

Donald Ellis, Ministère du Développement durable, de l'Envrionnement et des Parcs

The availability of safe freshwater is diminishing at an alarming rate globally. Increasing human population is stressing water supplies and contributing to water pollution. Population density increases and climate changes including epic droughts in certain parts of the world have led to the utilization of non-conventional water resources. These resources include desalinated sea water and recycled water to meet potable water needs. The water quality in many parts of the world is changing. The burgeoning human population taxes not only water resources but also food supplies, leading to rising demands for irrigation water and consequently to greater potential for water contamination by pesticides, fertilizers, and naturally occurring constituents. The public perception of water is shifting, with growing public awareness of certain groups of contaminants due to media coverage and non-government organization (NGO) concerns. Modern analytical technology has permitted the discovery that minute concentrations of contaminants of distinctly human origin occur in the water cycle. Many of these so-called “contaminants of emerging concern” have been, and will continue to be, detected in potable water supplies. Without question, the propensity for the contamination of fresh water will rise as human population continues to grow. Water treatment technology also continues to evolve. Advanced water treatment processes can provide effective and efficient contaminant removal. This presentation will describe the history, current status, and future implications that the detection of endocrine disruptors and pharmaceuticals will have on water and energy sustainability, with a particular emphasis on water treatment technologies.

Daniel Gerrity, Southern Nevada Water Authority

Membrane filtration processes are considered modern physicochemical separation techniques that have evolved into a technology that has been successfully used to treat a variety of source waters requiring removal of various contaminants ranging from individual ions to macromolecules and pathogenic protists. The presentation will focus on an overview of the four basic types of pressure-driven membranes currently used in water treatment and wastewater reclamation: microfilttration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse-osmosis (RO). Emphasis will be given to defining various operating characteristics, principal components and configurations, and typical target contaminants and removal performance for each membrane type. A discussion on how membranes can be integrated with other treatment processes will be included. An overview of membrane concerns with emphasis on membrane fouling will also be provided. The presentation will conclude with emerging directions and goals in membrane technology including the case study of using cationic exchange resins coupled with hollow fiber UF membranes to treat for copper in secondary wastewater treatment plant discharges.

Robin Collins, University of New Hampshire

Jim Malley, University of New Hampshire

Jim Malley, University of New Hampshire

One possible solution for securing additional drinking water sources is the reclamation of wastewater effluents using high-pressure membranes such as reverse osmosis (RO) and nanofiltration (NF). Uncertainty regarding the rejection of certain solutes, coupled with the increasing number of detections of emerging trace organics at the ppt-level in impaired water sources, justifies the development of modeling approaches that can adequately predict - a priori - the removal of contaminants by RO and NF membranes. A successful predictive model would eliminate the need for pilot-scale evaluation of trace organic contaminant removal, eliminate uncertainty regarding permeate water quality, and promote the implementation of water reuse projects employing membrane treatment.

This paper presentation will first summarize the findings from a recently completed project (Rejection of Wastewater-Derived Micropollutants in High Pressure Applications Leading to Indirect Potable Reuse) to highlight the factors that affect the rejection of organic solutes by NF and RO membranes. Finally, current efforts to develop models to predict the rejection of organic contaminants will be discussed including preliminary findings from a current project (Predictive Models to Aid in Membrane Design).

The fundamental research conducted to elucidate rejection mechanisms showed that the rejection of organic contaminants by NF and RO membranes is a function of solute properties, membrane properties and operational conditions. While the rejection of organic acids is generally high (> 90%) due to electrostatic effects, the rejection of uncharged organic solutes is variable and depends on molecular size, polarity, and hydrophobicity. Operational conditions that strongly influence rejection included permeate flux, recovery, degree of membrane fouling, and feed water quality parameters such as pH, ionic strength, and organic matter.

Several different membrane-modeling approaches are being investigated to describe and predict the rejection of organic contaminants based on solute and membrane properties, and operational conditions. These modeling approaches include empirical models that use statistical methods to relate solute and membrane properties to rejection, membrane transport models that employ mathematical representations of membrane systems, and hybrid models that combine empirical models and membrane transport equations. Past and ongoing modeling efforts show promise in describing the rejection observed during bench-, pilot-, and full-scale investigations.

Chris Bellona, Colorado School of Mines

Membrane filtration systems are increasingly being retrofit into existing water treatment plants to provide advanced treatment and/or additional capacity. Many alternative strategies are available for implementing membrane systems, such that utilities face a challenge in selecting the system that provides them the greatest benefit. As more and more long-term operating data is becoming available for various membrane systems, a survey of lessons learned from full-scale operating membrane treatment systems can provide information that may help utilities select a membrane strategy that is best for their system. This paper presents a survey of operational performance and cost data from the operation of six utilities that utilize common source water. Also presented will be discussion of challenges, successes, and lessons learned from the full-scale operation.

On the western shore of Lake Michigan, membrane filtration plants have been implemented in Lake Forest, Illinois, and in five cities in Wisconsin: Kenosha, Manitowoc (2 different membrane systems), Racine, South Milwaukee, and Two Rivers. As a source water, Lake Michigan (Great Lakes) is extremely cold (as low as 0.5°C) with low turbidity and low TOC; yet, a surge in turbidity (10 to 20 times the average) can take place based on wind strength and direction. Therefore, treatment of this type of water can sometimes be a challenge. Despite utilizing common source water, these plants represent a diverse array of membrane treatment strategies that include microfiltration and ultrafiltration pore size, pressure and submerged configurations, a range of pretreatment strategies, and a range of treatment capacity from 4 to 50 million gallons per day. These systems also cover a range in membrane technologies, including some of the earliest large-scale membrane filtration systems in Kenosha and Manitowoc, as well as the most recent submerged membrane technology at the new Manitowoc treatment plant.

This paper will compare the operational costs of the systems, including labor, power, chemicals, membrane replacement, residuals, and miscellaneous costs, and will highlight the impacts of type of pretreatment and membrane systems. This comparison provides information for benchmarking membrane plants and highlights important similarities and differences that can be used for planning and budgeting. Included will be a comparison between the costs of the membrane plants with the conventional plants that they replaced.

This paper will also include a survey of bright ideas, lessons learned, and optimization results from each plant, and focus on successful strategies that reduce costs, optimize capacity, and increase reliability. For example, at Manitowoc, small doses of aluminum chlorohydrate as pretreatment provided significant operational improvements, including simultaneous increases in flux and extended cleaning intervals of 35 percent and 400 percent, respectively. At Racine, optimization of the vacuum pump and permeate pump systems identified strategies for saving more than 20 percent on the overall power costs for the system.

Mark C. White, CDM

Chris Bellona, Colorado School of Mines

Extremely low levels of endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) have been detected in wastewaters, groundwaters, surface waters, and even treated drinking waters. While many questions are raised regarding the toxicological importance of trace levels of these contaminants in water, public perception and the professional engineering edict of protecting human and environmental health to the greatest extent demands we examine treatment of these contaminants to reduce their presence from our water supply.

Many studies have examined the efficiency of conventional and advanced treatment options for EDCs and PPCPs in wastewater and drinking water treatment, and successful treatment processes each possess advantages and disadvantages. For example, if one were to physically remove the contaminants from water (via membrane separations or adsorption processes), the presence of high levels of untreated EDCs or PPCPs in backwash or reject streams must be considered to avoid improper disposal of potentially hazardous compounds, and perpetual revolutions of the removal/disposal cycle. In addition, chemical oxidation processes (such as chlorine, ozone, and advanced oxidation) can lead to a suite of often unidentified products which may or may not contain residual EDC or PPCP activity.

This work offers an overview of utilizing advanced oxidation processes (AOPs) for treatment of EDCs and PPCPs in water. Results will be presented from several studies examining treatment of these compounds in drinking water, surface water, and even treated wastewater; from the perspective of contaminant oxidation via AOP and from the perspective of removal of contaminant associate biological activity. In addition, issues related to utilizing AOP in practice for treatment of these contaminants will be explored.

Erik Rosenfeldt, University of Massachusetts Amherst

As organic contaminants in drinking water are becoming measurable at lower and lower concentrations, so too are efforts to remove them or prevent their formation during drinking water treatment. Advanced oxidation process (AOP) technologies are among those which are being employed in this regard, either as dedicated treatment processes or as enhancements to existing treatment regimes (e.g. UV/H2O2 AOP enhancement of UV disinfection).

This presentation reviews some ongoing and recent research into the use of AOPs to mitigate a selection of drinking water contaminants of current interest. These contaminants include compounds such as geosmin and 2-methylisoborneol, which cause taste and odor at ng/L levels. The effects of AOPs on the formation and/or removal of potential carcinogens, such as N nitrosodimethylamine and related nitrosamine compounds, are also discussed. Some of these compounds exert human health effects at ng/L concentrations. Consideration is also given to the effects of AOPs on concentrations of pharmaceuticals and endocrine disrupting compounds that have recently been discovered to be present in source waters. While it may not be a priority for treatment facilities to target these contaminants for removal, those that practice AOPs for other purposes may realize removal of some of these compounds as an added benefit.

Susan Andrews, University of Toronto

Many utilities have begun to consider the potential use of higher dose UV light, together with hydrogen peroxide feed, as an advanced oxidation process (AOP). The use of UV AOP following membrane filtration and reverse osmosis has become a typical approach for indirect potable reuse projects world-wide. In addition, UV AOP has been evaluated on a handful of drinking water projects using lower quality source waters. With this early wave of projects, UV AOP represents an emerging technology for water treatment and water reuse. Understanding project experience and lessons learned from these early projects is critical in taking UV AOP from an emerging technology to a robust, proven process.

This paper will focus on summarizing key issues from three projects implementing UV AOP: the Luggage Point Advanced Water Treatment Plant (LPAWTP) in Brisbane, Australia, the Oxnard (CA) GREAT Program Advanced Water Treatment Facility, and the Aurora (CO) Reservoir Water Purification Facility (ARWPF). These projects, ranging from 6.3 to 50 mgd, represent three of the first UV AOP projects for municipal treatment. From the experience completing the research, design, and startup of these facilities, recommendations for how to implement an effective UV AOP project will be shared. Detailed design is nearing completion for Oxnard, and construction is rapidly progressing for the LPAWTP and the ARWPF. At the time of this presentation, the LPAWTP facility will be operational.

Results: Topics to be addressed include project planning tasks such as water quality sampling and analyses, the role of treatability testing, establishing performance targets and design criteria, addressing by-product formation and mitigation, addressing residual peroxide quenching, and selecting the appropriate UV lamp technology. Test results will be presented to demonstrate the performance of UV AOP for destruction of more than 30 compounds of potential concern (CPCs) including pharamaceuticals and personal care products.

Specific bench-scale test results will be presented demonstrating the effectiveness of UV AOP for the control of N-nitrosodimethylamine (NDMA) and eight other nitrosamines that are suspected carcinogens at parts per trillion concentrations. Data presented will include occurrence data for the nitrosamines in source water, along with destruction data by UV photolysis from the laboratory testing.

Engineering design considerations will be addressed including equipment procurement, establishing the system configuration, and accurately estimating capital and life-cycle costs. Additional topics covered will address performance testing and operations approaches to ensure project objectives are achieved.

Significance: UV AOP is an emerging technology of widespread interest in the water reuse and water treatment communities. The key findings from these three UV AOP projects are important to improve the understanding of the issues and implementation considerations for UV AOP.

Paul Swaim, CH2M Hill

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

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

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

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

Ronald Gehr, McGill University

Françis Barbe, Genivar

>Matthieu Decoste,

Uranium as radioactive element and/or heavy metal in different chemical compounds (such as carbonate, sulphate or similar) occurs both in ground water and surface water due to geogenic or anthropogenic reasons. In Germany, uranium can be detected in unaffected ground water in concentrations between less 1 to more than 100 µg per litre.
In its revised 2004 directive W.H.O. recommends a value of below 9µg/l; in Germany, U.S.A. and other countries values of between 30 and 10µg/l are recommended.

In our AMERICANA 2007 speech a suited treatment process for purification of uranium contaminated water was presented; just as a reminder: The introduced process presents an ion exchange technology on the basis of weakly basic ion exchanging materials (Uranex®).

Market and practical experiences in Germany, Sweden, Italy and the Czech Republic

1. Discussion of action value
Basis for all actions and activities should be binding threshold values for uranium,
In this speech we will present all results for potable water and all results for mineral water manufacturing, whereby the title “qualified for the production of baby food” is one significant aspect in the whole discussion.

2. Installed systems and applied technologies
There are two main reasons for clients to purchase a purification system: the content of uranium in potable water exceeds the threshold values significantly, or the content of uranium in mineral water resources exceeds the goal of the manufacturer.
The speech will give detailed information about the different purification technologies that have been applied in the installed systems.

3. What to do with the “residues”?
For all uranium removal systems there has to be a certified and approved way for disposing the residues, as all these systems generate weakly radioactive waste.
This speech will present 2 different ways of disposal/regeneration thus meeting applicable legal provisions.

4. Prospects and discussion.

Guenther Mann, ATC Dr. Mann GmbH

Seasonal climate changes influence surface water quality and sometimes force drinking water treatment facilities to process highly varying raw water quality. For these facilities, it can be a challenge to achieve consistently high quality drinking water. Increasingly stringent water quality regulations and decreasing membrane costs have pushed towards the use of membrane systems in water treatment plants.

The first membrane-based drinking water system in the province of Québec was commissioned in July 2008. The plant is located in the city of Beaupré and treats raw water from the Sainte-Anne-du-Nord River. The system was designed to withstand feed water turbidity varying from 3 to 100 NTU, total organic carbon (TOC) from 4.7 to 15.0 mg/L and true color from 29 to 80 TCU, while always producing treated water quality within the Québec Government’s legislated limits.

A membrane system was selected based on its reliable process performance to achieve the desired water quality, notwithstanding the highly variable feed water quality, as well as its life cycle cost based on power, chemical and membrane replacement costs.

The facility has a capacity of 6 181 m3/d and consists of 3 trains of immersed membrane technology. The raw water is coagulated with polyaluminum chloride (PACl), sent to flocculation tanks, and then to the membrane basins without any settling step.

This paper will review the design aspects, startup and operational experience of this membrane plant. The operational data available to date in terms of membrane performance and water quality will be presented. The operational strategy (recovery, backwash, and maintenance cleanings) implemented for operation with coagulated feed water targeted for TOC removal will be detailed.

Francis Vaillancourt, GE Water & Process Technologies''

Ronald Gehr, McGill University

Dès l'année 2008, le programme Prime-Vert a mis à la disposition des exploitations agricoles une aide financière bonifiée de 16,4 millions de dollars afin d'intensifier leurs actions en vue de la préservation ou de l'amélioration de la qualité de l'eau en milieu agricole, tout en élargissant la gamme des mesures existantes. Cette aide couvrira jusqu'à 90 % des coûts rattachés à la mise en œuvre des mesures de lutte contre la pollution diffuse d'origine agricole qui auront été recommandées à la suite de diagnostics (voir la liste des mesures en annexe). Précisons qu'en vertu du Cadre stratégique pour l'agriculture, Agriculture et Agroalimentaire Canada poursuit sa participation financière au programme Prime-Vert, notamment pour les volets ayant trait à la réduction de la pollution diffuse.

Ces nouvelles mesures permettent également au secteur agricole de contribuer à la vaste démarche gouvernementale de lutte contre la prolifération des algues bleu-vert dans les lacs et les cours d'eau du Québec. Rappelons que le gouvernement du Québec a annoncé, en septembre 2007, un plan d'intervention de 200 millions de dollars échelonné sur une période de 10 ans ayant pour objet de résoudre cette problématique à la grandeur du territoire québécois. Le volet agricole de ce plan compte sur une enveloppe de 145 millions de dollars. Comme d'autres secteurs d'activité, l'agriculture fera sa part en améliorant ses façons de faire.

Le plan d'intervention gouvernemental propose un accompagnement professionnel et une aide financière bonifiée, au bénéfice des exploitations agricoles; ces éléments profiteront à toutes les entreprises, mais de façon prioritaire au cours des trois prochaines années à celles qui exercent des activités dans les bassins versants touchés par les algues bleu-vert. En outre, les bassins versants agricoles à l'égard desquels le gouvernement du Québec agit déjà avec ses partenaires de l'Union des producteurs agricoles, d'Agriculture et d'Agroalimentaire Canada et de la Fondation de la faune profiteront également des nouvelles mesures. L'ensemble des exploitations agricoles situées dans les zones d'intervention prioritaires se verront offrir une aide technique pour trouver les solutions les plus susceptibles d'améliorer la qualité de l'eau par le renforcement des mesures de lutte contre l'érosion, notamment en s'appuyant sur des diagnostics précis. Des conseillers agricoles proposeront des correctifs appropriés pour régler les problèmes propres à chaque établissement.

La conférence présentera également un bilan des actions réalisées à ce jour et un aperçu des objectifs liés à ce programme d’aide financière.

Raymond-M. Duchesne, Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec

Le lac Heney, situé dans la vallée de la Gatineau, se trouvait dans une situation précaire. L’établissement d’une pisciculture en bordure du lac, suivi d’une autorisation pour l’augmentation de la production, combiné à d’autres facteurs aggravants, a mené à une détérioration visible de la qualité de l’eau du lac. L’eau brouillée et la formation d’algues bleu-vert témoignent d’une contamination en phosphore. Depuis la fermeture de la pisciculture en 1999, la concentration de phosphore se maintenait à 25 μg/L et le lac ne semblait pas montrer de signes de récupération.

Plusieurs études, menées par des universitaires mandatés par la Fondation, organisme mandaté pour élaborer le programme de réhabilitation, ont permis d’établir que l’épandage de chlorure ferrique dans le lac permettrait de faire précipiter le phosphore. Le chlorure ferrique est un produit de la famille des sels inorganiques qui est couramment utilisé pour le traitement des eaux potables et usées. Ce produit est corrosif pour la plupart des métaux, mais ne représentait pas de risque de toxicité dans les ratios d’utilisation du projet. Le chlorure ferrique injecté dans le lac réagit avec l’eau pour produire un matériel insoluble, l’oxyhydroxyde de fer auquel le phosphore se lie et sédimente.

Un essai à l’échelle pilote dans une petite baie du lac qui avait été isolée à l’aide d’une membrane imperméable a confirmé l’innocuité du produit pour la faune et la flore et son efficacité pour la réduction de la concentration de phosphore. L’épandage à l’échelle du lac entier a donc été décidé. La firme Envir-Eau a été mandatée comme directeur de projet afin de prendre en charge tous les aspects administratifs, scientifiques et logistiques de l’application de la solution envisagée.

Plusieurs défis ont dû être relevés notamment la conception d’un système apte à distribuer ce produit hautement corrosif sous sa concentration initiale. Au niveau logistique l’épandage devait se faire dans la période de brassage automnale, période de l’année particulièrement difficile pour la navigation à cause, entre autres, d’épisodes de neige, de brouillard et de la formation des premières glaces. Également, il fallait composer avec des journées courtes nécessitant la navigation dans l’obscurité. De plus la livraison journalière du produit devait se faire sur des routes rurales peu appropriées pour le transport à une telle échelle.

L’introduction du FeCl3 s’est fait au moyen d’une barge de grande dimension sur laquelle était monté un système de pompage permettant le captage de l’eau du lac, le mélange de cette eau avec le chlorure ferrique et l’injection dans le lac de la solution réactive par l’intermédiaire d’une rampe immergée derrière la barge.

Le projet a été réalisé durant la période de brassage automnale du lac soit pendant 18 jours consécutif à partir du 14 novembre 2007. Aucun impact important sur le pH du lac n’a été relevé lors du suivi coïncidant avec l’épandage. Le 27 avril 2008, lors du brassage des eaux du printemps, le taux moyen de phosphore était de 10 μg/L. Selon l’Association pour la protection du lac Heney, ce taux est le plus bas depuis les 20 dernières années. Le lac sera suivi pendant les 7 années à venir afin de bien établir la baisse de la concentration de phosphore et son immobilisation à long terme dans les sédiments.

Gilles Fortin, WESA Envir-Eau

Karine Boily, WESA Envir-Eau

Aujourd’hui, pratiquement tous les bassins versants sont victimes de rejets industriels ou agricoles générant des pollutions par micropolluants et des toxines organiques. Ces pollutions peuvent présenter pour nombre d’usages de l’eau (ex : la production d’eau potable) un problème majeur. Il y a donc un grand intérêt à développer l’analyse sur site et/ou en ligne de ces micropolluants dans les eaux naturelles.

Le principe des analyseurs en ligne SPE-UV (Hocer) est de pouvoir suivre en continu la qualité de l’eau brute et/ou traitée et de donner l’alerte dans le cas de pollutions chroniques, accidentelles ou malveillantes de différentes natures. Ils permettent une détection de certains micropolluants organiques (hydrocarbures dissous, pesticides, polluants industriels, cyanotoxines, …). Pour atteindre ces performances, la technique de mesure repose sur une pré-concentration de ces micropolluants suivie d’une analyse par spectrophotométrie UV 1. Les polluants organiques, en général présents en trop faible concentrations, ne sont pas visibles lors de l’analyse par spectrophotométrie UV. La phase de pré-concentration de ces polluants est alors obligatoire pour pouvoir les détecter.

L’objectif de ce travail est donc d’élaborer un ensemble de procédures rapides et simples (pour une utilisation in-situ) permettant de diagnostiquer, selon la nature des micropolluants, l’existence d’une pollution organique anthropique dans les eaux naturelles.

Après avoir déterminé les limites de quantification (LQ) des différents polluants étudiés (par exemple : microcystine LR, isopropuron, …), à partir de la dérivée seconde du spectre UV (acquisition en cuve de trajet optique 100 mm), les travaux ont permis de mettre en évidence l’efficacité des techniques de pré-concentration des micropolluants que ce soit par extraction L/L ou par SPE. L’utilisation de ces approches individuellement ou combinées permettent la détection, l’identification et la quantification, de micropolluants organiques à partir du μg/L jusqu’au mg/L dans les eaux naturelles.

1 O. THOMAS, C. BURGESS, UV-Visible spectrophotometry of water and wastewater, editions Elsevier, 2007

Estelle Baurès, École des Hautes Études en Santé Publique