The membrane pore sizes at the treatment plant will be 40 nm (0.04 micrometres). The system will be made up of modules, and the total area of the membranes at the Henriksdal plant will cover an area of 1.6 million sq m.

The membranes will replace the final stage in the traditional sedimentation method.

The membranes are kept clean by blowing air over them, which removes sludge and particles that have got stuck.

• More efficient nitrogen treatment. Nitrogen emissions are expected to fall by 40 per cent, from 10 mg to 6 mg per litre. This will result in healthier water in Lake Mälaren and the Baltic Sea. More water can be treated within a smaller volume thanks to the membranes' efficient separation of sludge.
• The membranes do not allow particles and particle-bound contaminants to pass through. This will make it possible in future to aftertreat and treat wastewater further to remove bacteria, viruses, microplastics and drug residues.