A third digester in the Käppala wastewater treatment plant, Sweden

The Käppala plant in Lidingö receives wastewater from 1.5 million people in eleven municipalities to the north and east of Stockholm.

The plant is to be equipped with a third digester in order to create redundancy in the process and enable planned maintenance, as well as cope with increasing quantities of sludge. The new digester will be 9000 m³ in size, and will occupy a space that was blasted out of the rock.

Once everything is complete, nothing will be visible above ground apart from a small shelter for technical equipment.

The plant will also gain a new high-flow purge system, which will be installed to safeguard treatment capacity during abnormally high water flows.

This process equipment will also be placed within the rock and will increase the plant’s capacity from 5 to 8 m³/s.