A symphony of whirring pumps and gurgling pipes. That’s the sound of Renseanlæg Damhusåen. This isn’t your typical Copenhagen attraction. But it’s a vital part of the city’s lifeblood. Renseanlæg Damhusåen is one of Copenhagen’s major wastewater treatment plants. It’s run by BIOFOS. BIOFOS is Denmark’s largest wastewater treatment company. They handle the wastewater for 1.2 million people. That’s a massive responsibility.
Think about it. Every flush every shower every drop of wastewater from a huge part of Copenhagen. It all ends up here at Renseanlæg Damhusåen. It’s cleaned and treated. Then it’s released back into the environment. The plant is undergoing a major expansion. This is to handle increasing amounts of wastewater. The expansion is necessary due to urban growth and increasing rainfall. The goal is to minimize pollution in the Øresund. The Øresund is the strait that separates Denmark and Sweden.
But this isn’t just about cleaning wastewater. Renseanlæg Damhusåen is also a source of green energy. The sludge from the wastewater treatment is used to generate biogas and electricity. This energy is fed into Copenhagen’s grid. It helps power the city. The plant even has solar panels. These panels help power the plant itself. In 2024 BIOFOS announced that its plants had become climate-positive. They produce more renewable energy than they consume.
However things don’t always go smoothly. In 2025 a significant incident occurred at Renseanlæg Damhusåen. There was a breakdown during an expansion project. This caused a bypass. Mechanically cleaned wastewater was temporarily released directly into the Øresund. This lasted for about three days. Around 4000 cubic meters of wastewater per hour bypassed the biological treatment. BIOFOS worked hard to fix the problem. They poured concrete around a faulty pipe connection. The good bacteria in the treatment tanks were also affected. They needed time to wake up and start working again. BIOFOS worked quickly. Normal operation resumed within a few days. A detailed report on the incident was submitted to environmental authorities.
Renseanlæg Damhusåen is more than just a wastewater plant. It’s a symbol of Copenhagen’s commitment to sustainability. It’s a vital piece of infrastructure. It’s also a reminder of the constant effort involved in balancing urban development and environmental protection. It’s a story of innovation and the challenge of handling the city’s growing needs. Next time you use the toilet in Copenhagen consider the silent hum of the machines at Renseanlæg Damhusåen working tirelessly. They keep the city clean and help contribute to a greener future.