Despite the fact that the microplastics has received increased attention in recent years, there is still a lack of knowledge both about its occurrence in stormwater and about the function of stormwater treatment facilities for microplastics removal. A major knowledge gap is the lack of measured data both from stormwater itself and from treatment facilities. This applies to Sweden, but also internationally. Existing knowledge about the presence of microplastics in stormwater is incomplete and/or partly based on results from modeling; measured data are largely missing.
The presence of microplastics in the form of tire and road particles in urban snow from plow dikes has proven to be high. In some cities, removed snow is dumped directly into surface water bodies, while in other places it is dumped on landfills. From previous studies, it is known that (sediment) particles in snow largely stay on the ground after snow melt while only a fraction follows the melt water. Thus, there is potential to reduce release of microplastics by choosing snow management strategies.
The treatment performance of biofilters concerning microplastics has not been studied so far. Since biofilters are implemented to a large extent both in Sweden and other countries, data is urgently needed. The same applies to sedimentation plants.
The project will provide new knowledge about:
- Microplastics deposits and concentrations in stormwater (both road runoff and snowmelt)
- Spreading of microplastics when dumping snow in water bodies versus storage on land
- Treatment efficiency of stormwater sediment facilities and stormwater biofilters.
In summary, this project will have large potential to contribute with new and relevant knowledge for the scientific community, industry, municipalities, authorities, and consulting engineers.
The project is funded by the Swedish Environmental Protection Agency. Evaluation of the biofilter is carried out in Sundsvall in collaboration with MSVA and within the cluster Stormwater&Sewers. A previous sampling of snowmelt and stormwater to biofilter has already been carried out within the GreenNano project in collaboration with IVL.