Large-scale investment in the Baltic Sea

The Käppala wastewater treatment plant on the island of Lidingö, off the coast of Stockholm, currently treats the wastewater of over half a million people. Now, a large-scale investment to increase the plant’s capacity and create a cleaner Baltic Sea is made.

Over the next seven years, the Käppala Association will modify and upgrade the current wastewater treatment process in order to meet higher requirements and increase capacity so as to be able to treat the wastewater of greater numbers of residents. Hydria Water has been selected as a supplier, and will deliver chain scrapers and scum pipes for the Käppala plant’s clarifying tanks.

– We delivered chain scrapers to the Käppala plant eight years ago. The client was very satisfied with the installation and the systems that were delivered then, and we have had close contact and a good working relationship ever since. When all of the new chain scrapers have been delivered in 2023, we will have provided a total of 32 chain scrapers, which we are very proud of, Johan Fritz, Sales Engineer at Hydria Water, says.

The Käppala Association’s facilities are situated below ground in large rock shelters in the Käppala district, on the eastern part of Lidingö. The wastewater of roughly 500,000 people is carried to the plant via a 60 km-long tunnel system. At the plant, the wastewater of households, schools, industries, offices, and hospitals is treated. Sludge, phosphorus, and nitrogen are removed from the wastewater through mechanical, biological, and chemical treatments. The process takes place in several steps, and it takes one to two days for the treated water to be released into the Baltic Sea.

Between 2021 and 2027 the plant’s entire wastewater treatment process will be upgraded, and complemented with new technology in a new configuration. This will facilitate the removal of even more nitrogen, phosphorus, and organic pollutants – while at the same time increasing capacity.

– It is one of our largest ever projects, Johan says.

The project will be carried out in stages in order to allow the plant to remain operational; at present the first stage of the installation work is being undertaken by Hydria Water.

Photograph: Rikkard Häggbom