"Storm water from a residential street is led to the facility where it percolates through a plant-covered filter bed in which water is purified by means of a combination of biological and geochemical processes. This type of facility is very common in among others the USA and Australia", says Godecke-Tobias Blecken, researcher in Urban Water Engineering at Luleå University of Technology.
The preliminary results indicate that the purification performance of the biofilter is still good. The metal levels in the purified water were significantly lower than in the storm water. The results also show that the choice of filter material is of great importance for the purification capacity. If the focus is on treatment, it is important to choose a material with a low percentage of fine-grained sediments, low organic matter content and high adsorption capacity.
The study has been going on in Tyresö since July sampling some rainfall events. The plan is to sample more rain events during the winter and spring to evaluate seasonal variations. The results will be evaluated in Sara Eklund's master thesis.
The work is done in collaboration with Thomas Alarm (StormTac AB) and Tyresö municipality. The project is part of GreenNano and Dag&Nät at Luleå University of Technology.