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Wetlands implemented for treatment of stormwater on Utö

The Baltic Sea is surrounded by a huge drainage area, due to the many rivers flowing into the Baltic Sea. Nutrients and toxic pollutants originating from human activities end up in the marine environment. Stormwater management is an increasingly important issue in society due to urbanisation and increasing volumes of rainfall due to climate change. These challenges force the Baltic regions to develop stormwater treatment solutions that can clean stormwater effectively and ensure standard water quality and management in real time.

The first constructed wetland at Utö, with the two pools and the bay clearly visible.

Our group at KTH, together with our Baltic partners in the CleanStormWater project in Riga, Viimsi and Turku, are designing and testing new treatment systems, assess stormwater management solutions, develop e-monitoring systems for real time water quality management as well as establish centralised and decentralised stormwater solutions. Different stormwater treatment solutions and also e-monitoring systems will be developed, tested and/or implemented. Compared to manually collected samples, e-monitoring gives continuous information of physical parameters such as flow rate, turbidity, electrical conductivity and suspended solids. This not only helps municipalities to better monitor their stormwater quality and intervene rapidly when necessary, but also helps to identify the best technical solutions in the development stage. Since different geological, utilisation and/or urban situations will require different solutions, the project will use different sites around the Baltic Sea and evaluate different technological solutions including sedimentation, ponds, separators and bioretention systems.

KTH will collaborate with Initiative Utö on their study sites on the island of Utö. In Utö, two wetlands designed for stormwater treatment have recently been constructed (see figure 1), while a third one will be constructed to clean the stormwater from the Utö military-firing range in the near future. The wetland has an inflow from two ditches which combine in a sedimentation pond which has a circulation time of 48 hours during normal operations, the sedimentation pond is also the home of a number of crayfish. From there the stormwater is led to the wetland area, where plants treat the water. Then the water enters a pool where more substances can sediment. In this pool young peach and pike live and can grow so they will not be eaten by the three-spined stickleback which dominates the Baltic Sea. Lastly, the water is released to the Baltic Sea in a bay called Södra Fladen. The wetland is designed to decrease the amount of nutrients and heavy metals flowing into the Södra Fladen and by extension the Baltic Sea. By releasing more fully grown peach and pike to the Södra Fladen, the diversity of predatory fishes in the Baltic Sea have the ability to be restored.

Understanding the efficiency of the constructed wetland system for stormwater treatment needs careful evaluation of the water quality over a longer period of time. At these sites samples are taken from the inlet water, the process and the outlet water to evaluate the treatment efficiency. More specifically nutrients, heavy metals, PAH:s and oil are analysed in the samples. The CleanStormWater project is currently ongoing. Results from this project will give more insight to wetlands’ ability to treat stormwater and other properties such as habitat for wildlife, which can be implemented in other wetlands around the Baltic Sea. In addition, a better understanding of the implementation of e-monitoring in stormwater treatments, can promote the usage of similar systems in other treatment sites around the Baltic Sea.

Tobias Karlsson
Research Engineer, KTH


KTH Baltic Tech Initiative project (in Swedish)

Interreg CB project Cleanstormwater

How You Can Support Innovation by Spreading Inspiration

How many people do you think live in water-scarce areas? A wild chatter erupts in the classroom as the elementary-school students start debating my question. A hundred thousand! says a student. More, I say. A million? More! Two billion? Yes! A proud smile emerges on the face of the student who got the right answer. Then, a heavy atmosphere rapidly descends on the group as they intuitively begin to realize what it means. That day, the students gained deeper fundamental insights into the importance of water. That day, I visited as part of an event called ForskarFredag (Researchers’ Night).

Photo by Ben Libberton

Before visiting the class, I asked a talented coworker how I could inspire the students. He confidently exclaimed: Talk about something they are interested in! And so I started interacting with the students to find what made them engaged. The answer surprised me. One time I said: Talk to the person next to you, how do you think we can make drinkable water from seawater? Again, wild chatter ensued. Whenever I let the students discuss amongst themselves, the floodgates to inspiration would open. Filtering? Heat the water? Use local resources? And when I let them ask freely about our research, the questions went on and on in a steady stream. After 20 minutes of being flooded with questions, I had to stop answering because we were running out of time. The experience taught me that lots of young people share a deep common interest. An interest in science.

Another day, I happily visited a group of older students from all over the world. They were young people who had not yet started working as researchers, and they had joined in a competition for the best innovations in water technology (Stockholm Junior Water Prize). There, a young man from India told me: Where I grew up you cannot drink tap water because of all the contaminations. Actually, many of us work with water to change this. Looking at his friend, he continued: We have worked for a year on developing a technique called capacitive deionization to help with cleaning water. As I looked around the crowded room, I suddenly began to realize how much hard work people put in. They had insights about water, they were deeply interested science, and they passionately drove innovations.

A while back, researchers at KTH started a company based on the same capacitive-deionization technology. While small at first, their hard work rapidly expanded the company and lots of people can now enjoy the purified water that they are producing. Recently, the company made the list of top 41 startups in Sweden focusing on environmental technology. Their example clearly showed me how much we can achieve through hard work in water technologies. Now is the time when years of valuable fundamental research are finding their way to the larger society.

The end ties back to the beginning. Looking at these successes, I saw the company’s progress would not have been possible unless someone had first noticed how important water is and used their passion for science. And so, it starts with you and me. We could attend big events like ForskarFredag and the water competition. Or, you could simply start a conversation about water with a young person you know. Whenever we spread the knowledge and tap into young people’s interest in science, we are all building the solid foundations of a better tomorrow.

Johan Nordstrand
Doctoral Student at KTH


The ForskarFredag event will be held again in 2022 and researchers are encouraged to join. I would also like to extend my gratitude to all the teachers who invited researchers to their classes and got the students engaged. The event would not have been possible without you and I hope even more teachers are joining the event next year. More information:

Information about the competition (Organized by SIWI, hosted visit to KTH by WaterCentre@KTH):

The company:

More information about me:

Sustainable energy efficient water supply systems within the society

Climate change has contributed to Sweden experiencing water shortages in many provinces in recent years, and continued challenges with rampant climate change are likely to further accelerate this problem. In many other countries, the problem of water scarcity is much more pronounced. The UN report “World Water Development Report 2020, Water and Climate Change” describes a gloomy picture of the water situation in the world, e.g. As many as 2.2 billion people do not have access to drinking water. The UN warns that climate change will exacerbate this situation if measures are not taken in this area. Access to clean water and sanitation for all is one of the UN’s global goals (SDG6). Achieving these goals requires a restructuring of society’s infrastructure. The increasing water shortage will lead to more advanced treatment methods having to be used to produce our drinking water with an increased energy need for water treatment in society.

In the built environment, large amounts of drinking water are used for various purposes, such as hot water for shower, bath, and sink, but also for other functions such as toilet flushing and lawn watering. Significant amounts of energy, chemicals, water, and financial resources are required to maintain this system. As an example, around 11 TWh is used annually for heating domestic hot water in villas, apartment buildings and premises in Sweden, corresponding to an estimated cost of SEK 10 billion annually (Energy Situation 2020, STEM). Of these 11 TWh, the entire 3.5 TWh loads the electricity grid. In addition to this massive energy demand, domestic hot water heating drives up the power demand in society’s infrastructure for energy supply, which entails major challenges for both energy producers and grid owners.

It is interesting that only a small part of the water used in society today is used for functions that require the relatively high quality of drinking water. The remaining amount of water is used for other purposes such as toilet flushing, shower, dishes, laundry.

By recycling and managing most of this cycle locally at building or area level, the water system would be more resource efficient, partly from an energy and power perspective, partly from a water supply and use perspective. Thus, to increase resource efficiency in this area, water can be used better and in a more sustainable way if water can be recycled and heat recovery is introduced on a broad front.

How this can be done in the best way is not clear, today there are a number of different system solutions with different technical maturity levels. For these types of systems solutions to succeed in the society, interdisciplinary research is required.

Pressure from property owners, planners and construction companies regarding sustainable water systems already exists today, driven partly by energy requirements and partly by the environment and environmental certification requirements. Even though innovative system solutions are in demand, there are no complete solutions available due to that knowledge of opportunities is lacking.

This new project, to be executed by doctorial student Viktor La Torre Rapp and supervised by Dr Jörgen Wallin (KTH) and Dr Jesper Knutsson (CTH), aim to identify which solutions, recycling solutions or recycling solutions with associated system structures provide the best conditions for meeting the challenges identified regarding water supply in society.

The goal is to present which possible system solutions and methods are conceivable for implementation at different levels in the built environment from a life cycle perspective and which are not based on a list of criteria that cover aspects in regulation, acceptance, economy, environment, and health. This presentation should include an account of the identified solutions, how the overall financial picture is compared to current technology with maintenance costs included. A reference group consisting of property owners, planners and construction companies as well as water suppliers and producers will join in order to optimize the use of the outcome and enhance the implementation of possible solutions.
During the project one or more selected promising solutions will be implemented and validated in test beds, HSB Living Lab In Gothenburg and KTH Live in Lab in Stockholm.

The project is funded by E2B2 and will take place during 2021-2024.

Viktor La Torre Rapp, Doctoral Student, Dept. of Energy Technology, KTH School of Industrial Engineering and Management

On pikes and potatoes

On the island Utö in Stockholm’s southern archipelago they grow pikes and potatoes next to each other. You don’t believe me? Go see for yourself!

In the beginning of September I returned to this wonderful spot, along with some 50 academics, entrepreneurs, investors and environmentalists. The occasion that brought us here was the first Baltic Sea WaterTalks; a meeting of diverse professionals in search of practical solutions for challenges in the Baltic Sea.

KTH researchers visiting Utö’s famous windmill

People on the island of Utö have always depended on what nature gives, in one way or the other. While this might be said for all of humanity, it is never more obvious than on an island at sea. Already from the 12th century, it was the iron ore on the island that brought prosperity. After the mining was abandoned in the 19th century, all the trees were cut down to supply timber to the growing city of Stockholm. But fish was plenty and by the early 1900s, there were some 70 fishing boats stationed on Utö. Now there is only one part-time fisherman left. Instead, the island has become a popular tourism destination thanks to its unique nature, its heritage and birdlife. Yet again, nature provides the basis for local livelihood. But how do we make life in the archipelago sustainable after centuries of predatory resource extraction?

This is where the pikes and the potatoes come in. Initiativ Utö, a local NGO and also the host of the WaterTalks, has started to build “pike factories”. In these constructed wetlands and estuaries they aim to both restore the fishing stock and reduce nutrient loads. Nutrients in the run-off and sediments are collected through mechanical and biological methods and the estuaries are breeding places for pike. The pikes restore some balance in the local marine ecosystems and attracts sports fishers. The recovered nutrient is used in local small-scale farming, and seems to be particularly good for potatoes.

Restoration work in the estuary

Currently, two research groups from KTH are actively doing research on the pike factory wetlands. A team led by Guna Rajarao Kuttuva looks into monitoring techniques and optimisation of the wetland. Another team led by Zeynep Cetecioglu Gurol is investigating the potential of phosporous “mining” from the estuary sediments, where valuable phosphorous could be extracted as a commercial product. Research and innovation like theirs moves us towards “closing the loop” for food production on a whole new scale. Could the polluted seas become a source for valuable and scarce nutrients? Can we move towards a balance with nature and stop exhausting nature’s resources one after the other?

Thomas Hjelm of Initiativ Utö talking to Zeynep Cetecioglu Gurol in the wetlands

And most importantly, what to do with the potatoes? For my part, I prefer the Swedish traditional dish “raggmunk”, a type of potato pancake. I can tell you that the Utö potatoes grown on sludge from the pike factory, are particularly well suited for raggmunk. Bon appétit!

Oooh those raggmunks!


10 Utö potatoes

3 eggs

2 dl flour

4 dl milk

1 teaspoon salt


Grate potatoes coarsely

Mix egg, flour, salt and milk and add grated potatoes

Form small “beefs” into saucepan and fry on medium-high, rich with butter

Serve with lingonberries



Le chef at work – grating away in the kitchen

Why Water Matters for Nuclear Power

Ringhals power plant. Photo: Vattenfall

We tend to associate nuclear power plants with many different things: smoking cooling towers, Homer Simpson-like operators, or dramatic TV series like HBO’s Chernobyl. But something people generally do not associate nuclear power plants with are massive amounts of water. Still, water is at the centre of nuclear power’s historical development, contemporary challenges, and further future.

The connection between water and generating nuclear power goes back to the Industrial Revolution, when steam technologies such as boilers and steam generators were used to heat up water, turn that water into steam, and use the energy of that steam to generate power. However, this led to many steam explosions with deadly casualties. Countries like the U.S., France and Sweden enforced safety rules, which stipulated how the boilers had to be designed and what the allowed pressures and temperatures were.

In the 1950s, more and more countries saw the potential of using nuclear technologies to generate power. With its Atoms for Peace-program, the U.S. took the lead and promoted the reactor type they developed: the light water reactor. This reactor type uses normal water as a coolant and had its origins in both naval propulsion and fossil fuel power generation. This continuity thus made water-cooled reactors a relatively simple way of rolling out nuclear power fast.

The safety in nuclear power plants was therefore determined by the control of water and the understanding of thermal-hydraulic phenomena, such as transients and steam explosions. The pressure vessels, steam generators, valves, pipes, tubes, and pumps of nuclear power plants suddenly became subjected to the steam regulations of the Industrial age. This created new risks since these codes and regulations did not consider radiation. One of the codes that underwent revision was the Boiler and Pressure Vessel Code of the American Society of Mechanical Engineers (ASME). The Code started travelling and was, for instance, almost directly implemented in all Swedish nuclear power plants. Gradually but surely, nuclear safety regulations in the West became more ‘nuclear’ as the intersection between water, steam, steel, and radiation became better understood and nuclear accidents, such as Three Mile Island, pushed governments for more safety legislation.

For the USSR water was equally crucial along all steps of the nuclear lifespan, such as mining, fuel element production, exploitation, and the storage of spent nuclear fuel and radioactive waste. In general, all nuclear power plants were placed next to either a river, a lake or the coast – the latter being an exception. The most common source of coolant was river water. Interestingly, those rivers usually had to be previously ameliorated and often artificial water reservoirs were created.

A specific setup was used for so-called energy complexes, a special form of nuclear-hydrotechnical combine. They embodied the combination of nuclear and hydro power, agricultural irrigation, and fish cultivation in one location. Furthermore, constructing them meant to manipulate water bodies with newly created dams. In this way an energy complex was created to procure valuable synergies through the multiple usage and partial recycling of water.

Finding the right location was crucial for an envisioned energy complex. It needed to be a location with sufficient water supply, with suitable ground conditions, without earthquake or flood dangers. In addition, the complex needed to be within reasonable distance towards a (potential) industrial settlement to provide this population centre with electricity. Safe and ample water supply had to be considered during site selection and was one of the essential criteria for their construction. If there was not enough water, the complex could not be built.

A leading institute for the creation of energy complexes was Gidroproekt (Hydroproject). As the name suggests, Gidroproekt was a Soviet hydraulic research, design and construction agency. By joining its hydraulic expertise with newly introduced nuclear engineering, this institute was the very place where knowledge transfer between these two prestigious engineering communities took place. Here, the water-focused perspective prevailed and embedded nuclear technology into hydro-ameliorated aquatic systems. It promised prestige as well as quick results – and Gidroproekt readily delivered.

In sum, both in the East and the West, water played a crucial role in the development of nuclear power. In the West, knowledge about water was essential for developing nuclear safety practices. In the East, water was seen as a crucial resource, for powering energy complexes in the struggle for building a Communist state. Nuclear’s reliance on water meant that nuclear power plants and energy complexes were meeting places of different long-standing traditions and communities. Given the large number of water-cooled reactors in the world today, and including those under construction, it is fair to say that this crucial connection is there to stay.

Achim Klüppelberg & Siegfried Evens
Doctoral students at division for History of Science, Technology and the Environment, within the ERC-funded project Nuclear Waters