The wastewater treatment of the future — AFRY and Stockholm Vatten och Avfall ensure cleaner water in the Baltic Sea

In Stockholm, a historic step is now being taken: the overloaded Bromma wastewater treatment plant is being decommissioned, and the treatment of the future is being gathered in a state-of-the-art system at Henriksdal. The project is part of a transition where technology, environmental responsibility and collaboration go hand in hand to ensure clean water in our lakes and seas for future generations.

As a key player in one of the city's most comprehensive environmental initiatives, Stockholm's Future Wastewater Treatment (SFA), AFRY works together with Stockholm Vatten och Avfall (Stockholm Water and Waste) to ensure sustainable wastewater treatment for over one million citizens. AFRY contributes with an advanced automation solution based on the Siemens PCS7 platform that ensures efficient control and monitoring of the modernised treatment plant.

Slow down eutrophication for clean water

To limit eutrophication in the Baltic Sea, Sweden has committed to reducing emissions of phosphorus and nitrogen according to the Baltic Sea Action Plan and the EU's Water Framework Directive. After many years of serving the city, Bromma wastewater treatment plant is now overloaded and can no longer meet Stockholm's growing needs. We also need to protect the water in Lake Mälaren, where we swim and collect our drinking water. In the event of heavy rainfall, the capacity reaches its limit, which means that diluted untreated wastewater may have to be discharged into Lake Mälaren and the Baltic Sea. The older technology also does not meet the stricter environmental requirements or the increased amount of wastewater.

To meet these challenges and secure the wastewater treatment of the future, SFA is a crucial investment – a project that paves the way for a cleaner and more sustainable Stockholm. The Bromma wastewater treatment plant will shut down, and future wastewater will be led in a tunnel towards the Sickla plant at Hammarbybacken and the Henriksdal wastewater treatment plant that is being expanded.

With an increasing population and stricter requirements for environmental considerations, Stockholm Vatten och Avfall is renewing and modernising the city's wastewater treatment. AFRY plays a key role by delivering an automation solution that controls and optimises the treatment process.

The membrane technology, one of the world's most advanced solutions, is distinguished by both increasing purification capacity and ensuring cleaner water. It is based on the use of semi-permeable membranes to separate unwanted substances from water. It is a physical filtration method that works much like a very fine-meshed sieve where only certain molecules are allowed to pass.

The technology helps to remove microplastics and bacteria from wastewater, which means that the Baltic Sea can enjoy a greatly improved water quality. Emissions of nitrogen and phosphorus are reduced by 40 and 35 percent respectively, which is crucial in the fight against eutrophication.

Milestones on the road to the future of water treatment

Since the start of the project in 2017, AFRY has worked in close collaboration with Stockholm Vatten och Avfall.

"A major challenge is that the treatment plant must be fully operational at all times, so that the surroundings are not affected during the project. This has been made possible through competent project employees, good collaboration with the client and flexible resource management," Jerker adds.

The project, which is one of the largest investments in wastewater treatment in Stockholm, has already achieved several important milestones. With project completion scheduled for 2031, AFRY continues to move forward, decisively and purposefully, to deliver a state-of-the-art and future-proof automation system.

"The SFA project is large and complex with many challenges and ongoing changes. It is crucial for us at Stockholm Vatten och Avfall to have help from flexible consultants with a high level of expertise where we can handle changes together at short notice. This works well with AFRY", says Magnus Biderheim, responsible project manager at SFA.

The new treatment plant inside Hammarbybacken will be completed and preparations for the technical installations are in full swing with new applications for all functional areas with associated process systems, plumbing, electric power and lighting. AFRY's detailed design will start in 2025.

"Through our work in the SFA project, we take responsibility for future generations and show the way towards a sustainable future. I am confident that we will continue to execute the project well and solve any problems, so that the automation solution not only solves today's challenges, but also acts as inspiration for similar projects around the world," concludes Jerker.