Area-efficient stormwater treatment - Where? When? How? (2016-2023)

The overall aim with this project is to contribute with knowledge about different treatment components for stormwater and how these can be designed and integrated in densely built areas. The intention is to develop recommendations for municipalities concerning which aspects to be considered in planning and implementation of stormwater treatment facilities. The project will also contribute to knowledge about how stormwater ponds can be built in natural water bodies where surface is limited and how the treatment efficiency can be improved.

Today, most of the stormwater is still discharged directly out to the water bodies without any treatment, although it can be quite polluted. The most common stormwater treatment system implemented in Sweden is pond systems. However, there is a need for more surface efficient treatment systems and also a need for systems that separate dissolved and colloid pollutants from the water.

The project is divided into five sub-projects.

Coagulation and flocculation: I the first sub-project, coagulation and flocculation is evaluated as stormwater treatment with respect to how particles, colloids and dissolved pollutants are separated from the water phase. Different coagulants and polymers are tested, both in lab and pilot scale.

Shielded wet detention pond: I the second sub-project a pond system is built with flexible “walls” in a natural water body in Östersund. Lately, such pond systems have increased in popularity in areas where space is limited. Both the treatment function of the shielded detention pond as well as improvements such as aeration, floating wetlands and bottom grid structures will be evaluated.

Membrane filtration: In the third sub-project, membrane filtration will be evaluated for treatment of polluted stormwater in laboratory.

Reactive filters for stormwater treatment: In the fourth sub-project, reactive filter materials which can adsorb e.g. metals will be evaluated. These materials can be used in gully pot filters, in compact treatment facilities for roof or facade run-off or as additives in stormwater biofilter systems. As a first step, batch and column tests will be performed in laboratory and after that a zeolite filter system for run-off from the copper roof of the National Museum in Stockholm will be evaluated.

Strategies for implementation of stormwater treatment: In the last sub-project, a strategy will be developed to see how the evaluated treatment technologies could be integrated in existing treatment systems and also how these can be integrated in existing, densely built urban areas.

The project is led by the Urban Water engineering research group at Luleå University of Technology and is carried out in cooperation with Swedish municipalities such as Östersund and Stockholm, the Swedish National Property Board and with the companies Purac, Kemira, Järven Ecotech and VegTech. The municipality partners within the research center of excellence Stormwater&Sewers will contribute with input through workshops in the fifth sub-project.

The project runs during the period 2016-2020 and is funded by Formas in the amount of approx. 10 million SEK.

Researchers

• Annelie Hedström
• Inga Herrmann
• Fredrik Nyström
• Ivan Milovanovic