white paper THE RETHINK WATER NETWORK | RECREATIONAL WATER | MAY 2014
Rethinking pools to boost safety and minimise use of water, energy and chemicals
Safe pool solutions ensuring high water quality and minimised use of resources Rethinking pools to boost safety and minimise use of water, energy and chemicals Safe pool solutions ensuring high water quality and minimised use of resources Version 1.0
About this white paper This white paper was developed by the Rethink Water network in Denmark. The work is coordinated by the Danish Water Forum. The Rethink Water network consists of more than 60 technology and consulting companies, water utilities, water organisations and public authorities. It was established to support our partners internationally in developing the highest quality water solutions.
Quoting this white paper Please quote this white paper and its articles: “Kristensen, G.H. (Tech. Ed.) & Klee, P. (Ed.in C.), 2014. Rethinking pools to boost safety and minimise use of water, energy and chemicals. Safe pool solutions ensuring high water quality and minimised use of resources. The Rethink Water network and Danish Water Forum White Papers, Copenhagen. Available at www.rethinkwater.dk”
Editor in Chief Pia Klee, kickstarter for the Rethink Water platform [email protected]
Technical Editor DHI Gert Holm Kristensen [email protected] DHI Morten Møller Klausen [email protected]
Contributors COWI Torben Schack [email protected] Danish Rootzone Technology Jørgen Løgstrup [email protected] DHI Gert Holm Kristensen [email protected] DHI Morten Møller Klausen [email protected] inBlue Ole Grønborg [email protected] LiqTech Daniel Larsen [email protected] Rambøll Henning Hammerich [email protected]
Language Editor David Lalley, WordDesign
© The Rethink Water Network & Danish Water Forum 2014 Executive summary
Walking through the glass Even if the practical and legal requirements a day, which is much better than traditional with regard to the operation of public pools and systems that only remove pollution a few times door separating our old and water parks vary widely on a global scale, most a week, or even less. This filtration is typically our new facility you feel of the technologies used have hardly changed combined with other technologies to remove in the last 100 years. For over a century, chlorine the remaining particles. the huge difference between has been the preferred disinfectant for making the new and the classic pool sure the water is free of unhealthy bacteria and Improved ventilation – due to the lack of alternatives – the continued Much of the remaining by-products are then system. It really stresses use of chlorine is still the most realistic future removed with a gas stripper, UV technology and scenario. Yet large quantities are not always other equipment. The chlorinated compounds the need for public pools needed to keep the water safe, and lowering are also removed at the surface of the pool by to bring down the level of the chlorine content improves the water and new kinds of ventilation. Nowadays most venti- air, protecting people from the intense chlorine lation systems in swimming pools are designed clearly harmful chlorine odour and itchy eyes and skin. to keep the air over the water surface still, in by-products order to cut down evaporation and thus reduce Improved water treatment energy consumption. However, this is not good PER KERSMARK The mechanisms controlling the formation of for the health of those using these pools. CEO harmful chlorinated disinfection by-products FILBORNA ARENA, SWEDEN are very complex and still poorly understood, Improved overall resource efficiency but there is a general consensus that the forma- Another important perspective on the grow- tion rate increases with higher concentrations ing pool market is the trends towards larger, of chlorine. One option, therefore, is to lower advanced pools that in turn lead to an increased the pH of the water – a measure that some use of water, energy and chemicals. The risk countries have practised for years. Chlorine is that operating costs rapidly escalate. There occurs in a much more active form at a lower pH, are, of course, physical limits for how efficient a which means that the same disinfection effect very resource-intensive facility like a swimming can be achieved with a lower chlorine content. pool can become, but the opportunity to bring Another option is to redesign water treatment down the consumption of water, chemicals and systems to remove solid impurities more often energy is certainly available. This white paper in order to avoid the chemical breakdown of provides numerous examples of how owners of contaminants with chlorine. An optimised water public pools have reduced their operating costs flow and drum filters will remove 90 to 95 per and at the same time achieved a more healthy cent of solid organic substances up to 200 times environment.
First to embrace new concept, Sweden In Sweden, the Filborna Arena in Helsingborg was the first public swimming facility to embrace new technology concepts that avoid harmful chlorine by-products and thereby improve the indoor environment for swimmers. In 2010, new extended pool facilities, built as a green- field project, were added to the existing facility. A radically different water treatment concept, combined with an innovative air ventilation system, has reduced the level of chlorine by-products to detection limits, protecting people from an intense chlorine odour, itching of the eyes and skin, and respiratory ailments. In addition, the use of water, energy and chemi- cals were greatly reduced compared to the traditional facility, which is separated from the new by a glass door. In 2012 the Filborna Arena was the proud host of the Swedish swimming championships. (Courtesy: inBlue) WHITE PAPER - RECREATIONAL WATER | 4 Photo: Kontraframe/City of Copenhagen
white paper Harbour pool in central Copenhagen, Denmark In natural water environments as rivers, lakes and the sea, THE RETHINK WATER NETWORK | WASTEWATER | SEPTEMBER 2013 the quantities and flow of water are normally huge, and bacteria that are part of a natural balance break down contaminants resulting from people bathing. As a rather unique story, the harbour of Copenhagen has been transformed from an industrial port to a vibrant cultural and social centre of the city in just a decade. People now swim and enjoy water playgrounds in the city centre in an impressive natural outdoor pool – the harbour itself. The industrial water traffic is gone, so modernising the sewer system and diverting local rainwater improved the water quality so the City of Copenhagen was able to open this public harbour bath in 2002. Protection against wastewater discharges during heavy rainfall is managed by integrated wastewater strategies and innovative technology. An
In control integrated bathing water quality forecasting system measures sewer overflows, and hydrodynamic and bacterial of wastewater to protect people models simulate the water quality in the harbour. This system provides real-time information about whether or not and ecosystems the water quality complies with the EU Bathing Water Directive. Download the white paper on wastewater treatment, Efficient solutions for treatment of wastewater which is part of the same series as this white paper on www.rethinkwater.dk/wastewater WHITE PAPER - RECREATIONAL WATER | 5
1. A technology shift for better health and higher efficiency 1
2. Balancing safe water with a healthy pool environment 2
3. The full opportunities with an optimised design build from scratch 5
4. Upgrading of existing facilities to cut costs and improve water/air 9
5. Documenting performance of new water treatment technology 11
6. Design of water environments with no use of chemicals 15
If your goal is water efficiency, Denmark is ready as a partner 17 WHITE PAPER - RECREATIONAL WATER | 6 Photo: Iwan Baan
Outdoor pool World Expo 2010, China Many architects and designers are attracted and inspired by water and natural water environments. This was also the case when Denmark’s pavilion for the World Expo 2010 in Shanghai was designed by the award-winning Danish architectural firm BIG (Bjarke Ingels Group), and the Little Mermaid statue of Copenhagen was brought on a historic trip to China. The bronze-skinned statue has sat pensively on the edge of the harbour since 1913, created to commemorate the leading character in the 19th-century fairy tale The Little Mermaid by Danish author Hans Christian Andersen. It was brought to the World Expo 2010 as a token of China–Denmark friendship and as a symbol for the unique story of Copenhagen Harbour’s clean water, as explained on the previous page in this white paper. The pavilion was built around an artificial pond whose water represented the sea surrounding the statue at home in Copenhagen harbour. The water was kept clean and safe to take a swim in, using the same technology concept introduced in this white paper. (Courtesy: BIG and inBlue) WHITE PAPER - RECREATIONAL WATER | 1
1. A technology shift for better health and higher efficiency
Having worked most of Recreational water facilities are popping up water and energy rise, the risk is that operating everywhere in the world, with fun and exotic costs will go through the roof. my life in the facility, it is water environments featuring pools, water amazing to see this dramatic slides, river rides, wave surfing, spa relaxation Attention of politicians important and so on. These facilities extend from public Another argument for a technology shift lies change in water and indoor swimming pools for local citizens to major in the much healthier pool environments. Yet, air quality. Changing our waterparks as tourism destinations. Even if the the pool environment will probably not be a practical and legal requirements for operat- big selling point for most investors even if the Olympic-size pool to a family ing public swimming pools vary considerably many public swimming pools and water parks throughout the world, most of the technologies need to distinguish themselves from the many swimming centre with more used in these facilities have hardly changed in competitors that will be out there. The market pools was a complex project, the last 100 years, no matter where the facility is highly conservative and competitive, which is located,. The technologies most commonly means that the adoption of new technology since all the new equipment used for are sand filtration, activated carbon concepts requires solid documentation for their had to fit into the existing and chlorination, adapted from the purification economic validity. Attention from politicians of drinking water. and public authorities should then help push basement, but we were the pool market towards healthier and greener able to double the water Increased resource efficiency solutions based on relatively strict legislation, One argument for a technology shift lies in the which then creates a demand for innovation treatment capacity and potential for reducing the consumption of water, in the supply chain. In Denmark, the political energy and chemicals in a resource-intensive term “innovation promoting legislation” has still keep water and energy sector like swimming pool operations. Reduced already caught the attention of politicians as consumption the same consumption will play an increasingly important new Danish legislation (Number 623) for pools role in being able to follow the global trend strictly limits chlorine by-products and guides JAN ASBJERG towards larger and more advanced recreational pool owners towards reducing both pH and free Technical Manager water environments with more visitors, higher chlorine. It also requires automated measure- GREVE SWIM CENTRE, DENMARK temperatures and other features that make a ment of key parameters combined with daily facility even more resource-intensive. If the manual measurements by staff and frequent costs of increasingly scarce resources such as monitoring checks by an accredited laboratory.
Technology shift in pool water treatment The mechanisms controlling the formation of harmful chlorinated disinfection by-products are very complex and still poorly understood, but there is a general consensus that the formation rate increases with higher concen trations of chlorine. By removing solid organic contaminants from the pool water before they dissolve and are broken down by chlorine, the the water quality and indoor air will be considerably improved and less chlorine is needed. The photo shows a sample of particles, mainly skin cells, collected by a drum filter up to 200 times per day. Imagine how these, if not passed to the sewer as waste, will react inside a sand filter. With hot chlorinated water stressing these particles for 7 days or more the skin cells will be dissolved and then return to the pool creating lots of unnecessary chlorine by-products that swimmers and bathing guests then will inhale. (Courtesy: inBlue) WHITE PAPER - RECREATIONAL WATER | 2
2. Balancing safe water with a healthy pool environment
Lowering a pool’s chlorine Spending time in water is fun and gives numer- the steep rise in childhood asthma observed ous health benefits, but the moist, chlorine- over the past decades. In Germany, parents concentration is a three-step scented air is often part of the experience. For are therefore now advised to refrain from concept. First, the water over a century, chlorine has been the preferred baby swimming with children aged 0–2 years disinfectant to ensure the water is free of if allergies often occur in their family. Another flow is optimised to remove unhealthy bacteria and – due to the lack of important sign of problems with chlorine is the organic contaminants in alternatives – the continued use of chlorine is health of elite swimmers. Even though they still the most realistic future scenario. However, live a more healthy life than ordinary people, a mechanical instead of a large quantities of chlorine are not always research shows that they are diagnosed with needed to keep the water safe and free of asthma or asthma-like symptoms nearly twice chemical process. Secondly, bacteria, and lowering the chlorine content as often. So even if all elite athletes have an the pH is lowered to make protects people from the intense chlorine odour increased risk of asthma, regardless of the type and itching of the eyes and skin. of exercise taken, research has shown that elite the chlorine more active swimmers have a 50 per cent greater risk of and thirdly the ventilation Chlorine has negative health impacts asthma than tennis players, for instance. When chlorine reacts with organic and inorganic flow is designed to remove matter like sweat, saliva, urine and skin resi- Harmful by-products hanging in the air chlorine by-products from dues released from people, it forms disinfection The air in swimming pools may be the cause, by-products (DBP) that either remain in the as swimmers are often exposed to high levels the water surface water or evaporate into the air. The chlorine of trichloramines, which are by-products itself does not smell – the smell stems from formed when chlorine breaks down organic GERT HOLM KRISTENSEN the by-products formed when the chlorine materials. Trichloramine has a damaging effect Head of Innovation breaks down the impurities. Unfortunately, on the lungs, and Scandinavian researchers DHI a great deal of studies support that these suggest that this may be one of the causes of chlorinated by-products – especially chloroform the increased incidence of asthma for elite and chloramines – are more harmful than swimmers — The World Health Organization previously believed. The hypothesis laid down WHO set a trichloramine limit of 500 micro- by some researchers is even that the chlorine grams per cubic metre, as any higher level gives compounds contaminating the air of indoor the risk of acute injuries, but the researchers swimming pools are at least a partial cause of measured levels that are 8–10 times this figure.
Saline pools, Denmark Saltwater treatment is known to relieve certain types of skin diseases and is also known to have a natural disinfecting effect. These features are used in a very unique wellness centre on the island of Læsø, which is a former church converted into this modern wellness centre, supported by architects and engineers. In this part of Denmark, the highly saline groundwater concentrations have been mined since the Middle Ages and are a landmark of the island. This water is now used for the highly saline pools with concentrations of 30 per cent salt. However, the use of dissolved salt as an alternative to chlorine is not allowed by the current Danish legislation, but the facility has been able to get dispensation to operate the pools at a lower chlorine concentration than required by this legislation. (Courtesy: COWI) WHITE PAPER - RECREATIONAL WATER | 3
Heated indoor pool in hospital, Australia Recreational use of water can deliver important benefits to health and wellbeing. Yet, there may also be adverse health effects associated with recreational use if the levels of chlorine by-products in the water and air is too high. This is why the Hyrondelle private hospital in Sydney in Australia decided to opt for a new technology concept in its heated indoor pool. The pool is part of the hospital’s hydrotherapy facilities, which are used for graduated exercising and treatment and allow physiotherapists to target specific muscle groups effectively, because warm water and buoyancy assist movement and encourage pain relief. (Courtesy: inBlue and Aquazure)
Changing air ventilation streams Changing water treatment systems Higher disinfection effect with lower pH Most ventilation systems in swimming pools are Another way to improve pool environments Another issue is to lower the pH of the pool designed to keep the air over the water surface is by redesigning water treatment systems. A water, which countries such as Germany and still, in order to cut down evaporation and thus new technology concept has proved it possible Austria have practised for years. Chlorine occurs reduce energy consumption. As a result, one to improve the water quality and at the same in a much more active form at a lower pH, which way to improve the indoor environment is time reduce the use of chlorine. The key is to means that the same disinfection effect can to redesign the air flow for faster removal of remove solid impurities to avoid the chemical be achieved with a lower chlorine content. chlorine by-products. Scientific studies of the breakdown by chlorine. An optimised water Lowering the pH to the recommended level of three-dimensional air flows in swimming pools flow removes the organic matter as fast as 6.5–7.0 makes it necessary to add a little more have led to the development of a new design possible, with drum filters removing 90–95 per of the hydrochloric acid that is normally added. of the ventilation systems that draw away the cent of solid organic substances up to 200 times Further improvement of the water environ- air just above the water surface. This reduces a day (test by NSF, the Public Health and Safety ment might be possible, either through direct not only the swimmers’ exposure to potentially Organization in USA). This is much better than removal of chlorine by-products from the water harmful chlorine by-products, but also signifi- traditional systems that only remove pollution or by removal of the so-called precursors for cantly improves the indoor air environment of a few times a week or even less. This rapid by-product formation – for instance by avoiding the entire pool facility, which benefits the staff. removal will maintain a lower chlorine concen- accumulation of particulate organic matters in However, changing existing ventilation systems tration because the chlorine no longer has to the filters of the water system. into the new design is often difficult. degrade the organic materials. WHITE PAPER - RECREATIONAL WATER | 4
State-of-the-art aquapark, Sweden Around fifty swimming pools have so far embraced the new standardised concept and the new Hyllie Waterpark currently under construction in Malmö in Sweden is one of them. When opening in 2015, the facility will be among the largest water parks in Scandinavia, with seven water treatment systems based on the new concept operating in the basement. This state-of-the-art facility will feature an indoor environment that is free of chlorine by-products and probably the most energy and water-efficient water park in the world. If compared to conventional systems in Sweden, the consumption of water and energy is reduced to just half. The facility is just 25 kilometres from Copenhagen, making it an attractive excursion destination for Danes. too. (Courtesy: inBlue) WHITE PAPER - RECREATIONAL WATER | 5
3. The full opportunities with an optimised design build from scratch
We started working with A collaboration involving scientists, owners of such as skin cells, urine, sweat, cosmetics and public swimming pools, a technology provider other impurities. If they are efficiently removed, scientists 10 years ago to and a research institute has resulted in the the chlorine compounds in the air above the rethink water treatment entire water treatment and ventilation concept basins are almost eliminated, and, in addition, of public swimming pools being rethought and much less chlorine is needed for disinfection. and ventilation of public optimised into a standardised concept. This swimming pools. Three rethinking extends from the way in which the The new concept contaminated water circulates in the pool over The new concept is divided into three steps. years later, our first full the many water filtration steps to the design Firstly, 3D computer modelling is used to of the air ventilation set-up. More than 50 improve the circulation of water in the pool in working pool was in place public pools in Denmark, Sweden, Australia and order to remove the impurities as swiftly as pos- reducing the use of chlorine Germany have implemented the concept so far sible. Secondly, the filter system is completely – many as greenfield projects, which gives the altered. In the usual sand filters, chlorinated by- by up to 80 per cent. New advantage of implementing the full concept. products are constantly generated when warm facilities, like the new Hyllie chlorinated water dissolves the impurities Radical thinking captured by the filter over a period of a week water park in Sweden, are The optimised water treatment and ventilation or two. With the new filter system, a drum filter the final result of optimising set-up is a radical new concept, and there is equipped with a filter screen makes sure 90–95 almost none of the traditional equipment in the per cent of the impurities released from the design and construction in technical spaces. The investment is the same as bathers are washed to the sewer within hours. for a conventional high-quality system and the To remove the last 5–10 per cent of particles, over 50 projects. This will financial gains are certainly there as the use of the drum filtration is normally combined with be the ultimate experience, water and energy are halved compared to the part-flow flocculant-enhanced sand filtration. most ideal design using classic technology such Many of the chlorine by-products are removed with the lowest possible as sand or DE-filter based systems. When start- with an air stripper, UV technology and other utility costs ing out in the development phase, the scientists equipment. Thirdly, new innovatie ventilation adopted a big-picture perspective by consider- principles are used to deal with any remaining OLE GRØNBORG ing the origins of the contaminants. Avoiding volatile chlorinated compounds at the water CEO these contaminants is impossible, but would surface of the pool. INBLUE it be possible to avoid the harmful substances resulting from chlorine breaking down such Using gravity instead of pumping contaminants? This led to the basic idea that The ideal way to achieve the lowest pos- chlorine is only used to ensure that people do sible operating costs, and the safest and not infect each other, not to break down waste most healthy environment, is when the water
Flow modelling The circulation of water must be optimised to remove the impurities as swiftly as possible. Flow modelling has three advantages over using standard construction design with standard fittings. 1. Particles are quickly transported to the cleaning system before dissolving 2. Treated water returns can be designed with a 90 per cent reduced head loss compared to standard returns, contributing to the overall reduced energy consumption. 3. Chlorine distribution is aligned perfectly with each unique pool design. The CFD model illus- trated is from the design of the pool with the Little Mermaid in section one. (Courtesy: inBlue) WHITE PAPER - RECREATIONAL WATER | 6
Reducing energy consumption by 25 percent, Denmark The ideal way to ensure the best possible environment and lowest possible consumption of energy, water and chemicals is to design the system on a green-field basis, fully integrated with the overall design of the build- ing. This was the opportunity open to the Valby Water Culture Centre, owned by the City of Copenhagen, which was built from greenfield. The building challenges the visitor’s senses with its irregular angles and inclined walls. From a water playground, the visitor enters a water world with entertaining water staircases, water tunnels, counter-current canals, caves, a large wellness area with hot water basins, etc. Working together, the technical consultant and architects were able to create a pool facility that uses 25 per cent less energy compared to other Danish public swimming pools using classic technology. (Courtesy: Rambøll) WHITE PAPER - RECREATIONAL WATER | 7
Upgrading of existing facilities, Denmark When Greve Swim Centre was renovated, the new water treatment concept was implemented to provide a more healthy indoor environment. The renovation project has turned this classic facility with an Olympic-size pool into a family centre with several pools instead. The project was a complex project because all new equipment had to fit into the existing basement, but it has paid off as the post-renovation water and energy consumption is on the same level as the old system, while the capacity of the water treatment system for the new – higher loaded – pools has been doubled, in accordance with the Danish national regulations. (Courtesy: inBlue)
All our students swim at treatment system is an integrated part of the of energy is consumed by the pool sector, so building’s design and as much water as possible increasing the energy efficiency should be school, and many of our elite flows by gravity rather than by pumping. In a a priority. In many countries, the incentives swimmers had respiratory building designed for best effect, it is possible to reduce energy consumption are big, and to achieve a total headloss, of less than one in Denmark, which has some of the highest problems. We therefore metre (3 feet) through the entire system, energy rates in the world, the need to reduce chose to be part of a three- from pool surface through equipment in the energy consumption has fuelled architects basement and back through the treated water and engineers to come up with a variety of year research project and return. A traditional sand or DE-filter system innovative many interesting projects. Besides needs at least 10 metres (30 feet) of head, or 10 minimising the evaporation from the pools, are now very proud to be times more. Dramatic reductions in energy use efficient heat recovery from ventilation systems able to tell new students will be needed to meet forthcoming demands is important as is optimising the buildings for for reduced environmental impacts and sustain- the use of both active and passive solar heating. that we offer them the most ability of swimming pools and water parks. Energy consumption for lighting system can be healthy pool in Denmark greatly reduced by using the latest LED fixtures. Energy-efficient buildings A design with a more natural ventilation during RENÉ THOMSEN Besides an energy-efficient design of technical the summer months saves heat and electricity Vice-Principal installations for ventilation and water treat- for ventilation systems. Also heat recovery BERNSTORFFSMINDE ment, it is important to have energy-efficient through heat exchangers for transfer of heat CONTINUATION SCHOOL, DENMARK swimming pool buildings. Designing everything from used shower water to heating the new from scratch is an interesting challenge and shower water is a common feature in public important opportunity for innovation. A lot pools and water parks.
Elite swimmers dropping asthma medicine The first development stage of the concept of improved water treatment and air ventilation was carried out at the Bernstorffsminde Private Continuation School in Denmark. The school serves young people as well as young elite swimmers. When the development project was kicked off, six of the 20 swimmers attending the school had asthma, but shortly after the new concept was implemented all of them stopped using asthma medication. This was also the case at other public pools with elite swimmers, which have also reported swimmers being able to dispense with their asthma medication. The photo shows Sabine Devantier Christensen explaining in Danish national news how her asthma problems disappeared when training for competitions in the Bernstorffsminde pool. WHITE PAPER - RECREATIONAL WATER | 8
Solving challenges expanding outdoor facilities, Denmark The tropical holiday and activity centre Lalandia located in the southern part of Denmark faced a set of challenges when expanding its outdoor facilities, as the load is extremely heavy in warm and sunny holiday seasons. The extension included a new children’s pool, a large spa pool and a new water slide able to handle 2,600 people per hour, corresponding to 20 times the capacity of the traditional water slide. Water treat- ment must always be dimensioned to a pool’s maximum bathing load and installing a drum filter before conventional sand filters proved to be a solution able to handle this intense load. In addition, 3,000 tons of water (800,000 US gallons) were saved as the backwash water of both membrane filters and sand filters is regenerated and reused for the basins as well as for backwash of the sand filters. (Courtesy: Rambøll) WHITE PAPER - RECREATIONAL WATER | 9
4. Upgrading of existing facilities to cut costs and improve water/air
There are physical limits The market for swimming pools and water parks in water consumption might play a bigger role is trending towards larger, more advanced pools then as they are much more significant. Rede- for how efficient you can with higher temperatures and more resource- signing water treatment systems typically give be when renovating a very intensive features, leading to an increased use 50-60 per cent savings in water consumption of water, energy and chemicals. This involves compared to traditional systems. These are for resource-intensive facility a risk that operating costs go through the roof instance achieved by reusing the regenerated like a swimming pool, but when energy and water prices are not stable. backwash water from the sand filters. A differ- However, investing in increased capacity goes ent and more radical step in the renovation pro- the opportunity to bring hand in hand with a more resource-efficient cess would be to swap most of the sand filters system design. The potential to improve pool for water- and energy-saving drum filters. Such down the consumption of environments and at the same time reduce the a solution might save more than 50 per cent in water, chemicals and energy use of resources certainly also exists for existing water consumption. pools. The best time to look into this is when is certainly there an overall renovation is coming up. The limited Significant savings in energy consumption space available for technical installations in Upgrading water treatment systems also leads HENNING HAMMERICH current facilities is rarely a limitation, because to energy savings. Typically 20-30 percent Senior Consultant RAMBØLL modular and highly engineered designs make it savings in electricity consumption and 15-20 easy to fit new technology elements into space- percent savings in heat consumption can be constrained facilities. achieved. Savings might also be found by replacing old recirculation pumps with mordern Reduced use of chlorine and water energy-efficient pumps. This can be combined Besides ensuring much fewer harmful chlorine with redesign and replacement of the piping, by-products, a shift to new technology provides aiming towards reduced headloss for the large up to 30 per cent savings in chlorine. This may recirculation flows and with new intelligent not make a great difference in the overall cost control of the recirculation flow adapting to the picture, but for most operators it is still a benefit actual number of pool users, and operating with to reduce chlorine consumption. The savings a reduced flow during the night.
Upgrading public swimming pool, Denmark When the public swim centre in Køge was renovated and upgraded to a new capacity of 300,000 visitors per year, it involved renova- tion of the roof, steel structures, ventilation, plumbing, electrical systems and a new water treatment system. The water flow within the existing technical areas was increased by almost 60 per cent, thereby improving the water quality in the pools, baby pool and hot tub. This technical solution includes drum filters, which remove larger particles, and polymer membrane filters for removing the fine particles that make up 10–15 per cent of the organic mass. Regenerated water is reused for priming and backwashing the membrane system. The total savings achieved are a reduc- tion of energy consumption by 20 per cent and water consumption by 55 per cent. (Courtesy: Rambøll) WHITE PAPER - RECREATIONAL WATER | 10 Photo courtesy:: Danish Arthritis Society
Online monitoring reveals potential for system optimisation Detailed online monitoring of water quality has helped the public swimming centre in Gladsaxe, Denmark reduce its electricity consumption for pumping by 40 per cent, because the water flow is now automatically adjusted according to the numbers of pool users. In addition, the online monitoring has been used to test and comprehensively document four different UV-based technologies for reducing the level of combined chlorine. The efficiency of the technologies as well as the financial picture involved in installation and operation were then evaluated on the basis of these results. The test proved that using these technologies to their full potential is possible when combined with on-line monitoring of combined chlorine, as they can be operated in energy-saving mode. (Courtesy: DHI) WHITE PAPER - RECREATIONAL WATER | 11
5. Documenting performance of new water treatment technology
To push technology change, Positive health effects and an increased technology, combined with comprehensive need for resource efficiency in recreational performance testing and documentation, the performance testing facilities can push the pool and water park not only help to fine-tune the technology. It and documentation of new markets towards new water quality standards. also provides an important support in setting However, any radically change of basic water new standards for water quality and water water treatment technology treatment concepts is indeed a challenge treatment systems in swimming pools. should include solid data because in most places the pool market is both highly conservative and very competitive. Solid Testing response of the entire system for the response of the documentation for the performance of new Temporal variations in water quality parameters water treatment technology is therefore crucial make the testing and documentation of tech entire pool system. We have for a market breakthrough, since investors nology performance difficult. This is due to documented huge temporal are normally positive with regard to using the complex interaction between bather load, technology suppliers as a source of information. chlorine reaction chemistry, circulation and variations in water quality treatment of water, which together govern using advanced online Supporting market breakthroughs the water quality in recirculated pool systems. Pool facilities are often operated in accordance This complexity makes it insufficient to test monitoring techniques with relevant national legislation, and this is new technologies just by characterising the market situation that technology suppliers the efficiency of the addition or removal of MORTEN MØLLER KLAUSEN have to address. The day-to-day checking of specific components. The testing must include Senior Process Research Engineer water quality is a low-frequent grab sampling DHI a monitoring of the response of the entire and analysis, and online data from the plant pool system, which is further complicated control system is not used to check and optimise because the water quality parameters are low the pool system. This means pool owners in concentration and difficult to measure. This and technical staff do not normally have any then means the testing and documenting of extensive knowledge and understanding about new water treatment technology requires that the workings of their systems. They often comprehensive in-depth monitoring of water only rely on documentation from technology quality is conducted using both frequent off- suppliers. As a result, a supplier’s in-depth line measurements as well as online monitoring knowledge of the underlying fundamental of the most relevant parameters. physico-chemical mode of action of a particular
New filter technology saving water For the new public swim centre in Randers in Denmark, investment in new filter technology was good business. The centre’s hot water pools and a 50-metre Olympic pool will be kept clean with a new filter technology called ceramic membrane filtration in the six water treatment systems. This technology replaces the classic sand filters. For this facility, flushing these sand filters would have required up to 100 cubic metres of water per week. Instead, the ceramic filters fitted with a membrane made of silicium carbide are automatically cleaned with air and just a small amount of fresh water. This reduces the water consumption by as much as 90 per cent, which for a large Danish facility like this amounts to annual savings of 30,000 euros. (Courtesy: Provital Solutions and Liqtech) WHITE PAPER - RECREATIONAL WATER | 12 WHITE PAPER - RECREATIONAL WATER | 13
THM reduced when chlorine is reduced Trihalomethanes (THM) are unwanted volatile components formed in pool water as a result of the reactions between the chlorine and the pollution caused by the bathers. The figure shows the impact on THM formation at two different chlorine concentrations in a warm pool. At the low chlorine level of 0.4 mg/litre, the THM in the pool water is around 20 µl/litre while at the higher chlorine level of 1.5 mg/litre the THM level is 40–50 µl/litre. This leads to the conclusions that pools should be operated at the very lowest level of chlorine possible, just ensuring the hygienic quality of the pool water. (Courtesy: DHI)
Huge variations in water quality over time water quality. In addition, a better insight into the pool water quality and operations. A Research in pool water chemistry over the the parameters of importance to the pool water better understanding of the link between last decade using advanced online monitoring quality has shown that the traditional direct the dynamics of the water quality with the techniques has shown that the concentrations coupling between the circulation of pool water variations in treatment plant and system of disinfection by-products and related water for chlorine distribution and the treatment operation as well as bather load is needed, quality parameters are highly variable both for maintaining the pool water quality is and can be accomplished with comprehensive within a single hour and from day to day. inappropriate. Improved knowledge about monitoring. This monitoring should include Observed by-products are trihalomethanes the actual processes taking place in the pool using online monitoring and frequent off-line (THM) and combined chlorine, which are water will therefore open up new possibilities measurements and registrations of bather load, both regulated normally, and water quality for optimised technology/system design with thus establishing the data required for system parameters dissolved organic carbon (DOC). reduced energy consumption combined with analysis and documentation. Based on such Observations have clearly shown that plant improved water quality. data, improvement options can be identified operation – as well as the interpretation of and prioritised based on their cost and ease experimental results – may be misleading Potential improvements in pool operations of implementation. The effect is normally and unable to show correlations between the Many facilities therefore have unexploited documented by a follow-up monitoring performance of processes/technologies and potential with regard to significantly improving programme.
Huge variations in pool water quality Many pool facilities have unexploited potential for significantly improving both the water quality and pool treatment operations through a better understanding of how the dynamics of the water quality interact with variations in treatment plant concept, system operation and bathing load. The figure illustrates the daily and day-to-day monitoring in trihalomethane concentrations in a warm water pool measured during technology assessments using advanced online monitoring technology. (Courtesy: DHI) WHITE PAPER - RECREATIONAL WATER | 14
Water playground used in all seasons, Denmark Water is often used to enhance the urban environment and this is also the overall idea for a new water-activity playground in one of the parks in central Copenhagen, the capital of Denmark. In this playground the universal story of water is paired with the story of the city for children and youngsters to get a playful and natural understanding of water and how it plays a key role in day-to-day life, both in history and in the present day. They get a unique opportunity to combine play and exercise, and also cool off in the hot summer months. It is built as a city and shows the water flowing from clouds via the city’s rivers and sewers and into the ocean. While some activities run automatically, other activities require physical activity to work. The playground works both with and without water, and will therefore also be used as an ordinary playground outside the summer season. The water used is – for health reasons – clean drinking water delivered by the city’s water supply and the plant is emptied every day after use. (Courtesy: Force4 Architects) WHITE PAPER - RECREATIONAL WATER | 15
6. Design of water environments with no use of chemicals
For recreational water In many cities, recreational water is an it is still important to ensure the water is of a increasingly important element of the city’s sufficient quality and safe, not placing people’s facilities designed without development, in urban planning and in land- health at risk. chlorine disinfection, it is scaping. The inhabitants in urban areas often value water highly and in many different ways Designing safe solutions essential to always carry because it influences – for instance – local Ensuring and checking the water quality should climate, humidity, air pollution and health. therefore always be a core element in recreational out a proper quantitative In addition, the sound and view of water are water designs. The required water quality always microbial risk analysis. always a pleasure for people – both adults and depends on what it is to be used for. For instance, children alike. Along with this, the increasing an acceptable level of microbial organisms in an This ensures that the water risk of extreme weather events and heavy aquarium is higher (poorer water quality) than is kept safe and pathogens rainfall causing damage in urban areas can be the acceptable level of microbial organisms in an tackled with integrated solutions that both outdoor city swimming facility, where bathers do not spread to an unaccep- deal with the water and provide citizens with may ingest the water. In the design of water table extent, which would recreational value at the same time. environments, an assessment of health risks should therefore always be conducted to define an make many people sick Ensuring safe water always important acceptable level of safety and a correspondingly Builders, architects, landscapers, engineers acceptable level of water quality. An acceptable HANS-JØRGEN ALBRECHTSEN and artists are thus integrating water risk could be equal to the risk accepted in the Professor, Department of as a key feature in urban environments. European Bathing Water Directive. Such a risk Environmental Engineering Recreational water extends from fountains, assessment comprises a hazard identification TECHNICAL UNIVERSITY OF DENMARK water sculptures, aquariums and park lakes (what are the relevant pathogens), evaluation of over swimming pools and wellness centres exposure (pathogen dose) and calculation of the to outdoor city baths and beaches. Many try risk of infection. Any requirements for treatment to avoid the use of chemicals because of their efficiency to the applied treatment systems are many negative aspects, but in all recreational thus determined by comparing the acceptable situations where people are exposed to water quality with the quality of the available water.
Rootzone treatment, Netherlands The open-air swimming pool in Amersfoort in the Netherlands uses local groundwater and each day 3–15 cubic metres (800-4,000 US gallons) of fresh water is pumped into the pool, depend- ing on the levels of evaporation and other kinds of water loss. Dimensioned for the needs of 2,500 visitors a day, the water is circulated and treated in a constant flow around a 300-square metres rootzone island. The volume of the pool is 5,000 cubic metres (1.3 million US gallons) and each day 150–600 cubic metres of water (40,000-160,000 US gallons) is filtered and treated by the rootzone filter constructed with a high content of hard lime sand. The rootzone is covered with reeds – Phragmetis Australis – and is part of the natural wetland. (Courtesy: Transform Danish Rootzone Technology) WHITE PAPER - RECREATIONAL WATER | 16
Independent advisor ensuring best technical solution, Denmark In some cases it is of great value to not just rely on technology providers, but to hire an independent advisor to help decide on the best technical solution. The Blue Planet in Copenhagen, which is currently northern Europe’s largest and most modern aquarium, used an independent consulting company when designing what is today the most advanced – but also most cost-effective – water treatment system for aquariums. The many advanced recirculation solutions and different types of water to be treated fill the basement of the aquarium with 4,500 square metres (nearly 50,000 square feet) of advanced technology. The tender documents and the associated technical requirements were prepared by a Danish consulting company with the main goal of minimising the energy and water consumption. Each of the 12 recycled water treatment plants was thus systematically described and the potential resource savings were defined. For instance, to save energy, emphasis was placed on placing each water treatment plant at the same height as the actual aquariums, and on using pipework with a low pressure drop. The contractor was also asked to establish drives for pumps and use energy-saving pumps. To save water, for instance, the salt water aquariums take in water from the sea at a depth of 10 metres and 1,600 metres in the sea when the salinity is high enough, the water for plants in the Amazon and freshwater aquariums are collected rainwater. The backwash water from all the filtration steps is passed to a shared tank where it is cleaned and then reused. (Courtesy: COWI) WHITE PAPER - RECREATIONAL WATER | 17
If your goal is water effi ciency, Denmark is ready as a partner
Danish water companies Denmark is surrounded by water, yet freshwater For mutual benefi t is still a scarce resource for us. For 30 years, As a country, we see great opportunity for have shown their courage we have been rethinking water and building mutual benefi t in the transfer of knowledge and drive by working with expertise within water effi ciency. Today, our tap and the growth in both partners’ business. water is as pure as the fi nest spring water and Our expertise is in assisting customers and their competitors in order the water in the harbour of Copenhagen, our stakeholders reach safe and eff ective water to create the Rethink Water capital, is so clean that people swim in it. solutions, while developing their ability to profi t from that knowledge. In our work we maintain platform. They are showing Denmark knows water a healthy respect for diff erent perspectives and the world that Denmark is The knowledge we have about water resources , agendas, as well as for the environment. water security and water effi ciency is no ready to take responsibility coincidence. Successive governments have Rethinking water together and contribute to fi nding addressed our country’s limited natural resourc- Rethink Water is a global network specialising in es, concentrating on using them effi ciently, and water effi ciency. So far, we are over 60 consult- solutions to the major water as a nation we strive to provide a safe, pleasant ing companies, technology providers, utilities, challenges the world faces and healthy environment for people to live in. research institutes and governmental bodies. The network brings together an unusually KIRSTEN BROSBØL Knowledge transfer diverse and valuable mix of clients, consultants, Minister for the Denmark is not physically powerful, but know- researchers, technology experts and govern- Environment ledge is power. Long ago we as Vikings spread mental bodies. We have joined forces to share DENMARK fear across the seas. Today, we want to spread knowledge and create even better water something entirely diff erent: know ledge and solutions, in Denmark and around the world. collaboration on how to globally protect water We invite you in to collaborate on solving your resources and improve water effi ciency. Water water challenges and to explore our expertise is an increasingly scarce resource in most parts at www.rethinkwater.dk/whitepapers of the world. We need to rethink how we use it.
Technology companies Research Export Customers Solutions for organisations credit agency and their water effi ciency Consulting stakeholders companies Government and worldwide Public authorities Organisations
Water utilities WHITE PAPER - URBAN WATER | 1 WHITE PAPER - RECREATIONAL WATER | 18
Consulting companies Find more white papers, learn more Alectia alectia.com Bonnerup Consult bonnerup.net about the Rethink Water network COWI cowi.com EnviDan envidan.com and get in touch with us at: Gromtmij grontmij.dk Moe & Brødsgaard moe.dk Orbicon orbicon.com NIRAS niras.com www.rethinkwater.dk Rambøll ramboll.com TREDJE NATUR tredjenatur.dk Øllgaard ollgaard.dk
Technology companies Adept Water Technology adeptwatertech.com AKVA group Denmark akvagroup.com Aquaporin aquaporin.dk AVK avkvalves.com Billund Aquaculture billund-aqua.dk Biokube biokube.com Blue Control bluecontrol.dk Danfoss danfoss.com Danish Rootzone Technology rootzone.dk EcoBeta ecobeta.com Envotherm envotherm.com Freewater freewater.dk Grundfos grundfos.com HOH BWT hoh.com I -GIS i-gis.dk Kamstrup kamstrup.com LiqTech International liqtech.com MJK Automation mjk.com Mycometer mycometer.com NOV Flexibles nov.com/fps Novozymes novozymes.com OxyGuard International oxyguard.com PROAGRIA Environment proagria.dk RK Plast rkbioelements.dk Scandinavian No-Dig Centre no-dig.dk Siemens siemens.com/energy/aeration Silhorko-Eurowater eurowater.com SkyTEM Surveys skytem.com Sorbisense sorbisense.com Stjernholm stjernholm.dk UltraAqua ultraaqua.com Wavin wavin.com Aarhus Geophysics aarhusgeo.com Per Aarsleff aarsleff .com
Research institutes & demonstration projects Danish Technological Institute teknologisk.dk DHI dhigroup.com Geological Surveys of Denmark and Greenland geus.dk Kalundborg Industrial Water Demonstration Site symbiosis.dk
Water utilities Greater Copenhagen Utility hofor.dk VCS Denmark vcsdenmark.com North Water nordvand.dk Aarhus Water aarhusvand.dk
Organisations related to water Association of Waterworks in Denmark fvd.dk AquaCircle aquacircle .org Copenhagen Cleantech Cluster cphcleantech.com Confederation of Danish Industry di.dk Danish Water Technology Group dk-water.com Danish Water and Wastewater Association danva.dk Danish Water Forum danishwaterforum.dk Danish Water Services danishwater.dk State of Green Consortium stateofgreen.com Water In Urban Areas Network waterinurbanareas.dk
Governmental bodies & other sponsors City of Copenhagen kk.dk Capital Region of Denmark regionh.dk Danish Trade Council um.dk BW Negative Logo / State of Green Danish Ministry of the Environment mim.dk
Grey Danish Nature Agency naturstyrelsen.dk C - M 0 - Y - K 10 The Branding Denmark Fund mfonden.dk Dark C 0 - M 0 - Y 0 - K 0