4 may 2015
Reclaiming waters to revive city life
A mermaid's tale
Perched on a rock on the edge of Copenhagen’s harbor, the Little Mermaid has gazed toward shore for over 100 years, in search of her prince. According to the fairy tale on which one of the world’s most famous sculptures is based, it is the hope of seeing her true love once more that draws her each day from the sea. Until recently, another motivation might have been escaping from the filthy depths.
For many years, the harbor, contaminated with sewage and industrial wastewater discharges, had been considered a public health hazard and been closed to swimming.
Today, following a major modernization of the city’s sewer system and installation of stateof-the-art control systems, Copenhagen’swaters are safe for humans and mermaids alike. The harbor has become a tourism and recreation hub and its revitalized waterfront neighborhoods are vibrant and trendy.
Copenhagen is just one of an increasing number of examples of the technology and infrastructure investments being made by cities as they confront the increasing pressure being placed on water resources by skyrocketing urbanization.
Booming cities, water worries
Urban populations worldwide are growing at a rate of two people per second. Within two decades, nearly 60% of the world’s population will live in cities. In the developing world, urban areas gain an average of five million residents every month. Exploding population growth – in cities and generally -- is placing unprecedented strain on resources. Among the most critical: ensuring adequate water and sanitation.
While urbanization brings opportunities to improve water resource management and increased access to drinking water and sanitation, population growth is outpacing our ability to devise solutions, according to the UN. In the past decade, the number of urban dwellers who lack access to a water tap in their home or immediate vicinity has risen by an estimated 114 million and the number of those who lack access to the most basic sanitation facilities by 134 million. The resulting impacts can be measured in both human and economic terms, through increased disease and lost productivity of people too sick to work.
Cities in developing countries, while not faced with the same lack of basic human infrastructure nonetheless face pressures to optimize their water resources. Strained public finances, water shortages and wasted economic opportunity are all driving implementation of more sustainable practices -- whether recycling and reusing water, finding solutions to prevent storm water contamination or maintaining public bathing and lake resources vital to quality of life and local economies.
Keeping swimming safe
Around the world, cities are looking to new technological solutions to improve water resource management.
Copenhagen’s success in making its harbor fit again for public swimming was made possible through a multi-year investment in modernizing its sewage system and the installation of large storage tanks.
Wastewater treatment plants are now equipped with STAR®
Control systems from Krüger, a Veolia Water Technologies subsidiary. This real-time control system minimizes sewer overflow by controlling pumps and gates within the sewer system to reduce potential environmental impacts from combined sewage overflow. Consumption of energy and chemicals is minimized while the quality of the outlet is maintained or even increased. In addition to improving health conditions and quality of life for Copenhagen’s citizens, the investments are paying off economically as well, increasing harbor area property prices and spurring the openings of new shops and restaurants.
In the French Mediterranean city of Antibes, bathing water quality is assured through a biological wastewater treatment and clarification system managed for the municipality by Veolia. In addition, meteorological monitoring provides real-time warning of potential storm water overflows, allowing local authorities to control access to the community’s beaches prior to any possible pollution events. The system is thus essential to protecting public safety and avoiding harm to the area’s critical tourism industry.
Protecting against storm water overflow
Veolia’s storm water solutions are helping other cities manage sanitary sewer overflow treatment requirements prior to discharge. The BioACTIFLO® process combines biological treatment with the ACTIFLO®
microsand ballasted high-rate clarification system, providing highly effective removal of suspended solids and biological oxygen demand (BOD).
In the northern French city of Lille, a new city-center wastewater treatment plant is meeting the growing needs of the population and contributing to sustainability. In addition to wastewater, the plant treats storm water using the ACTIFLO®
process. The Veolia-built plant also generates a low carbon footprint and produces biogas from sludge.
Back in Denmark, in Copenhagen’s new eco-district of Ørestad, the ACTIFLO®
process is used to treat surface water from a pumping canal in the community’s “open water system” of lakes, canals and water basins. In just minutes, the ACTIFLO®
plant reduces suspended solids and phosphorus by up to 95% and greater to produce high environmental quality water. The plant’s flexibility means it can be started and stopped automatically several times a day or for long periods. Its fully automatic operation typically requires the presence of personnel only a few hours a week.
In the Alcântara district of eastern Lisbon, Portugal’s newest and most modern wastewater treatment plant manages discharges from Lisbon as well as the neighboring municipalities of Amadora and Oeiras. Two ACTIFLO®
clarification units provide storm water treatment while other sections of the low carbon footprint, sustainable-design unit provide primary treatment, biological treatment and sludge thickening.
Within two decades, nearly 60% of the world's population will live in cities
Water is too valuable to be used only once
Such processes are making possible continued industrial growth in water scarce regions
Reusing a precious resource
In the city of El Prat de Llobregat near Barcelona, Veolia technology is helping the community make optimized use of scarce water resources. The El Prat Water Reclamation Plant treats the secondary effluents from the Metropolitan Area of Barcelona wastewater treatment plant, meeting Spanish chemical and biological quality standards for urban, agricultural, industrial, recreation and environmental uses. The plant’s processes include ACTIFLO®
tertiary clarification, followed by Hydrotech™ microscreen Discfilters
, UV disinfection and chemical disinfection. Then, one part of the treated water is processed by an ultrafiltration and reverse osmosis unit, so that it can be reinjected into the aquifer and act as a barrier against saline intrusion.
Seventy miles down the Mediterranean coast, Veolia’s Camp de Tarragona Water Reclamation Project (pictured below) is also helping to relieve water scarcity. By efficiently treating municipal secondary effluent to meet local industry’s process water needs, freshwater can be used for municipal drinking water supplies to meet the region’s evergrowing water demands. The plant reclaims water from treatment plants serving the Tarragona and Vila-Seca i Salou communities, applying tertiary treatment through reverse osmosis as its main process. The reclaimed water is primarily used in cooling towers by companies operating in Tarragona’s Petrochemical Complex industrial zone. To meet the high water quality criteria required by the industrial end users, municipal wastewater is treated with an ACTIFLO®
system, followed by Veolia’s Hydrotech™ Discfilter
microscreen filtration technology and then two-stage sand filtration. The pre-treatment solution offers efficiency in removing high concentrations of total suspended solids and organic compounds from secondary effluent, thus preventing organic fouling and bio-fouling in the reverse osmosis stage. Such processes are making possible continued industrial growth in water scarce regions through improved industry sustainability.
In Sydney, Australia, a forward-looking sustainable design strategy has made the Darling Quarter office and leisure development a model for new inner city development projects. In addition to designing, building, operating and maintaining the buildings’ recycled water plant, Veolia implemented a total water cycle management plan to achieve a range of social, economic and environmental benefits. Actions included installing high efficiency fixtures and fittings and treating sewage to produce high quality recycled water used for cooling towers, garden irrigation and toilet flushing. In addition, rainwater collected from the building roofs is filtered, UV treated and distributed to the public domain for landscape irrigation and to meet other water resource needs of the local community.
Among the achievements: a 92% reduction in potable water consumption, saving the equivalent of 86 million bottles of water per year, and a 2,500-ton CO2 reduction in the buildings’ carbon footprint.
In Shenzhen, China, the Xili wastewater treatment was the rapidly growing city’s first wastewater reuse plant. The plant receives domestic wastewater and produces treated effluent that meets national discharge standards, supplementing water supplies drawn from the Shahe River. Equipped with Veolia’s Multiflo™
biological filter and ACTIFLO®
ultimate settler technologies, the plant has a daily water recycling capacity of 50,000m3
In Dubai, Veolia is keeping the water pure in the artificial lake bordering the world’s tallest tower, the Burj Khalifa Tower, part of an enormous residential, commercial, leisure and
entertainment complex. The company built the water treatment installation and manages plant operations for the 300,000 cubic meter lake, one of the development’s most spectacular elements. The lake is fed with previously treated storm water and topped up with freshwater to offset evaporation. The 62,400 cubic meters/day treatment plant includes the storm water treatment facility and recycling equipment. Installed Veolia technologies include four ACTIFLO®
modules, four Hydrotech™ Discfilters
, an ACTIDYN®
sludge treatment module as well as two belt filter presses for sludge dewatering.
A final example is found again in Denmark where a major priority is protecting the aquatic environment of the Inner Lakes, one of Copenhagen’s most popular recreational areas.
Among the needs is ensuring the lakes are supplied with sufficient amounts of fresh water and maintaining the correct nutrient balance to reduce algae growth, improving water clarity and oxygen conditions, thus preserving flora and fauna. An ACTIFLO®
plant at Lake Emdrup plays an important role in maintaining the improved quality of the water that flows to the Inner Lakes, removing phosphorus and reducing COD and suspended solids.