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 door separating our old and our new facility you feel the huge difference between the new and the classic pool system. It really stresses the need for public pools to bring down the level of clearly harmful chlorine by-products
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
water parks vary widely on a global scale, most
a week, or even less. This filtration is typically
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.
Improved water treatment
energy consumption. However, this is not good
PER KERSMARK CEO FILBORNA ARENA, SWEDEN
The mechanisms controlling the formation of
for the health of those using these pools.
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 greenfield 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-productsto detection limits, pro tecting people from an intense chlorine odour, itching of the eyes and skin, and respiratory ailments. In addition, the use of water, energy and chemicals 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)
has been the preferred disinfectant for making 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
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
needed to keep the water safe, and lowering
are also removed at the surface of the pool by
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
odour and itchy eyes and skin.
to keep the air over the water surface still, in order to cut down evaporation and thus reduce
harm ful chlorinated disinfection by-products 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
coun tries 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.
WHITE PAPER - RECREATIONAL WATER | 4 Photo: Kontraframe/City of Copenhagen
white paper THE RETHINK WATER NETWORK | WASTEWATER | SEPTEMBER 2013
In control of wastewater to protect people and ecosystems Efficient solutions for treatment of wastewater
Harbour pool in central Copenhagen, Denmark In natural water environments as rivers, lakes and the sea, the quantitiesand flow of water are normally huge, and bacteria that are part of a natural balance break down contaminantsresultingfrom people bathing. As a rather unique story, the harbour of Copenhagen has been transformedfrom 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 Copenhagenwas 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 integratedbathing water quality forecasting system measures sewer overflows, and hydrodynamic and bacterial models simulate the water quality in the harbour. This system provides real-time information about whether or not the water quality complies with the EU Bathing Water Directive. Download the white paper on wastewater treatment, 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 my life in the facility, it is amazing to see this dramatic change in water and indoor air quality. Changing our Olympic-size pool to a family swimming centre with more pools was a complex project, since all the new equipment had to fit into the existing basement, but we were able to double the water treatmentcapacity and still keep water and energy consumption the same
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.
JAN ASBJERG Technical Manager GREVE SWIM CENTRE, DENMARK
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 considerablyimproved 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)
water environments featuring pools, water 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
swimming pools for local citizens to major
in the much healthier pool environments. Yet,
waterparks as tourism destinations. Even if the
the pool environment will probably not be a
practical and legal requirements for operat-
big sellingpoint for most investors even if the
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
used in these facilities have hardly changed in
competitors that will be out there. The market
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
used for are sand filtration, activated carbon
concepts requires solid documentation for their
and chlorination, adapted from the purification
economic validity. Attention from politicians
of drinking water.
and public authorities should then help push the pool market towards healthier and greener
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
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
sector like swimming pool operations. Reduced
already caught the attention of politicians as
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
towards larger and more advanced recreational
pool owners towards reducing both pH and free
water environments with more visitors, higher
chlorine. It also requires automated measure-
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.
WHITE PAPER - RECREATIONAL WATER | 2
2. Balancing safe water with a healthy pool environment Lowering a pool’s chlorine concentration is a three-step concept. First, the water flow is optimised to remove organic contaminants in a mechanical instead of a chemical process. Secondly, the pH is lowered to make the chlorine more active and thirdly the ventilation flow is designed to remove chlorine by-productsfrom the water surface GERT HOLM KRISTENSEN Head of Innovation DHI
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
scented air is often part of the experience. For
are therefore now advised to refrain from
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 allergiesoften occur in their family. Another
unhealthy bacteria and – due to the lack of
important sign of problems with chlorine is the
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,
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
bacteria, and lowering the chlorine content
as often. So even if all elite athletes have an
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 swimmers have a 50 per cent greater risk of
Chlorine has negative health impacts
asthma than tennis players, for instance.
When chlorine reacts with organic and inorganic matter like sweat, saliva, urine and skin resi-
Harmful by-products hanging in the air
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
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
the by-products formed when the chlorine
materials. Trichloramine has a damaging effect
breaks down the impurities. Unfortunately,
on the lungs, and Scandinavian researchers
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
measuredlevels 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 substancesup 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 systemsthat 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 scientists 10 years ago to rethink water treatment and ventilation of public swimming pools. Three years later, our first full working pool was in place reducing the use of chlorine by up to 80 per cent. New facilities, like the new Hyllie water park in Sweden, are the final result of optimising design and construction in over 50 projects. This will be the ultimate experience, with the lowest possible utility costs
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,
and a research institute has resulted in the
the chlorine compounds in the air above the
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.
OLE GRØNBORG CEO INBLUE
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 illustrated is from the design of the pool with the Little Mermaid in section one. (Courtesy: inBlue)
optimised into a standardised concept. This 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.
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
public pools in Denmark, Sweden, Australia and
order to remove the impurities as swiftly as pos-
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-
advantage of implementing the full concept.
products are constantly generated when warm chlorinated water dissolves the impurities
Radical thinking
captured by the filter over a period of a week
The optimised water treatment and ventilation
or two. With the new filter system, a drum filter
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
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,
financial gains are certainly there as the use of
the drum filtration is normally combined with
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
as sand or DE-filter based systems. When start-
with an air stripper, UV technology and other
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
ing the origins of the contaminants. Avoiding
volatile chlorinated compounds at the water
these contaminants is impossible, but would
surface of the pool.
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
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 building. 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 equipmenthad 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 school, and many of our elite swimmers had respiratory problems. We therefore chose to be part of a threeyear research project and are now very proud to be able to tell new students that we offer them the most healthy pool in Denmark
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
increasingthe energy efficiency should be
flows by gravity rather than by pumping. In a
a priority. In many countries, the incentives
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
metre (3 feet) through the entire system,
energy rates in the world, the need to reduce
from pool surface through equipment in the
energy consumption has fuelled architects
basement and back through the treated water
and engineersto come up with a variety of
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,
times more. Dramaticreductions in energy use
efficient heat recovery from ventilation systems
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.
ability of swimming pools and water parks.
Energy consumption for lighting system can be
Energy-efficient buildings
A design with a more natural ventilation during
RENÉ THOMSEN Vice-Principal BERNSTORFFSMINDE CONTINUATION SCHOOL, DENMARK
Besides an energy-efficient design of technical
the summer months saves heat and electricity
installations for ventilation and water treat-
for ventilation systems. Also heat recovery
ment, it is important to have energy-efficient
through heat exchangers for transfer of heat
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.
greatly reduced by using the latest LED fixtures.
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 treatment 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)
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4. Upgrading of existing facilities to cut costs and improve water/air There are physical limits for how efficient you can be when renovating a very resource-intensive facility like a swimming pool, but the opportunity to bring down the consumption of water, chemicals and energy is certainly there HENNING HAMMERICH Senior Consultant RAMBØLL
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-
with higher temperatures and more resource-
signing water treatment systems typically give
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
a risk that operating costs go through the roof
instance achieved by reusing the regenerated
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-
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
environments and at the same time reduce the
a solution might save more than 50 per cent in
use of resources certainly also exists for existing
water consumption.
pools. The best time to look into this is when 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
current facilities is rarely a limitation, because
to energy savings. Typically 20-30 percent
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
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 renovation 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 reduction of energy consumption by 20 per cent and water consumption by 55 per cent. (Courtesy: Rambøll)
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.
WHITE PAPER - RECREATIONAL WATER | 10 Photo courtesy:: Danish Arthritis Society
Online monitoring reveals potential for system optimisation Detailed online monitoringof water quality has helped the public swimming centre in Gladsaxe, Denmark reduce its electricityconsumption for pumping by 40 per cent, because the water flow is now automaticallyadjusted according to the numbers of pool users. In addition, the online monitoring has been used to test and comprehensively document four different UV-based technologiesfor 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 possiblewhen combined with on-line monitoring of combined chlorine, as they can be operatedin energy-saving mode. (Courtesy: DHI)
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5. Documenting performance of new water treatment technology To push technology change, the performance testing and documentation of new water treatment technology should include solid data for the response of the entire pool system. We have documented huge temporal variations in water quality using advanced online monitoring techniques MORTEN MØLLER KLAUSEN Senior Process Research Engineer DHI
Positive health effects and an increased
technology, combined with comprehensive
need for resource efficiency in recreational
performance
facilities can push the pool and water park
not only help to fine-tune the technology. It
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
treatment concepts is indeed a challenge
treatmentsystems in swimming pools.
and
documentation,
because in most places the pool market is both highly conservativeand very competitive. Solid
Testing response of the entire system
documentationfor the performance of new
Temporal variations in water quality parameters
water treatment technology is therefore crucial
make the testing and documentation of tech for a market breakthrough, since investors nology performance difficult. This is due to are normally positive with regard to using the complex interaction between bather load, technologysuppliers as a source of information.
chlorine reaction chemistry, circulation and treatment of water, which together govern
Supporting market breakthroughs
the water quality in recirculated pool systems.
Pool facilities are often operated in accordance
This complexity makes it insufficient to test
with relevant national legislation, and this is
new
the market situation that technology suppliers
the efficiency of the addition or removal of
have to address. The day-to-day checking of
specific components. The testing must include
water quality is a low-frequent grab sampling
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 technicalstaff do not normally have any
then means the testingand documenting of
extensiveknowledge 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
know ledge 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)
testing
technologies
just
by
characterising
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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 dynamicsof the water quality with the
techniques has shown that the concentrations
coupling between the circulation of pool water
variationsin treatment plant and system
of disinfectionby-products and related water
for chlorine distribution and the treatment operationas well as bather load is needed,
qualityparameters are highly variable both
for maintaining the pool water qualityis
and can be accomplished with comprehensive
within a single hour and from day to day.
inappropriate.
about
monitoring. This monitoringshould include
Observed by-products are trihalomethanes
the actual processes taking place in the pool
using online monitoringand 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 optimisedtechnology/system design with
thus establishing the data required for system
parametersdissolved 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
Improved
knowledge
and prioritised based on their cost and ease
operation – as well as the interpretation of 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
documentedby
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)
a
follow-up
monitoring
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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 opportunityto 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)
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6. Design of water environments with no use of chemicals For recreational water facilities designed without
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
development, in urban planning and in land-
health at risk.
chlorine disinfection, it is essential to always carry
scaping. The inhabitants in urban areas often value water highly and in many different ways
Designing safe solutions
because it influences – for instance – local
Ensuring and checking the water quality should
out a proper quantitative microbial risk analysis. This ensures that the water is kept safe and pathogens do not spread to an unacceptable extent, which would make many people sick
climate, humidity, air pollution and health.
therefore always be a core element in recreational
In addition, the sound and view of water are
water designs. The required water quality always
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
risk of extreme weather events and heavy
aquarium is higher (poorer water quality) than
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
deal with the water and provide citizens with
may ingest the water. In the design of water
recreational value at the same time.
environments , an assessment of health risks
HANS-JØRGEN ALBRECHTSEN Professor, Department of Environmental Engineering TECHNICAL UNIVERSITY OF DENMARK
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, depending on the levels of evaporation and other kinds of water loss. Dimensioned for the needs of 2,500 visitors a day, the water is circulatedand 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 contentof hard lime sand. The rootzone is covered with reeds – Phragmetis Australis – and is part of the natural wetland. (Courtesy: Transform Danish Rootzone Technology)
should therefore always be conducted to define an Ensuring safe water always important
acceptable level of safety and a correspondingly
Builders, architects, landscapers, engineers
acceptable level of water quality. An acceptable
and artists are thus integrating water
risk could be equal to the risk accepted in the
as a key feature in urban environments.
European Bathing Water Directive. Such a risk
Recreationalwater extends from fountains,
assessment comprises a hazard identification
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.
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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 consultingcompany 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)
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If your goal is water efficiency, Denmark is ready as a partner
Danish water companies have shown their courage and drive by working with their competitors in order to create the Rethink Water platform. They are showing the world that Denmark is ready to take responsibility and contribute to finding solutions to the major water challenges the world faces KIRSTEN BROSBØL Minister for the Environment DENMARK
Denmark is surrounded by water, yet freshwater
For mutual benefit
is still a scarce resource for us. For 30 years,
As a country, we see great opportunity for
we have been rethinking water and building
mutual benefit in the transfer of knowledge
expertise within water efficiency. Today, our tap
and the growth in both partners’ business.
water is as pure as the finest spring water and
Our expertise is in assisting customers and
the water in the harbour of Copenhagen, our
stakeholders reach safe and effective water
capital, is so clean that people swim in it.
solutions, while developing their ability to profit from that knowledge. In our work we maintain
Denmark knows water
a healthy respect for different perspectives and
The knowledge we have about water resources,
agendas, as well as for the environment.
water security and water efficiency is no coincidence. Successive governments have
Rethinking water together
addressed our country’s limited natural resourc-
Rethink Water is a global network specialising in
es, concentrating on using them efficiently, and
water efficiency. So far, we are over 60 consult-
as a nation we strive to provide a safe, pleasant
ing companies, technology providers, utilities,
and healthy environment for people to live in.
research institutes and governmental bodies. The network brings together an unusually
Knowledge transfer
diverse and valuable mix of clients, consultants,
Denmark is not physically powerful, but know-
researchers, technology experts and govern-
ledge is power. Long ago we as Vikings spread
mental bodies. We have joined forces to share
fear across the seas. Today, we want to spread
knowledge and create even better water
something entirely different: knowledge 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 efficiency. 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
Customers and their stakeholders worldwide
Solutions for water efficiency
Research organisations
Export credit agency Consulting companies
Government and Public authorities
Organisations Water utilities
WHITE PAPER - URBAN WATER | 1 WHITE PAPER - RECREATIONAL WATER | 18
Find more white papers, learn more about the Rethink Water network and get in touch with us at:
Consulting companies Alectia alectia.com Bonnerup Consult bonnerup.net COWI cowi.com EnviDan envidan.com Gromtmij grontmij.dk Moe & Brødsgaard moe.dk Orbicon orbicon.com NIRAS niras.com Rambøll ramboll.com TREDJE NATUR tredjenatur.dk Øllgaard ollgaard.dk
www.rethinkwater.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
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Governmental bodies & other sponsors City of Copenhagen kk.dk Capital Region of Denmark regionh.dk Danish Trade Council um.dk Danish Ministry of the Environment mim.dk Danish Nature Agency naturstyrelsen.dk The Branding Denmark Fund mfonden.dk