Nutrient reduction in constructed wetlands

We have developed a three-step model to calculate retention of the nutrients (nitrogen and phosphorus) in the constructed wetlands.

In the first step, hydraulic loading to an actual or potential wetland is calculated, based on inflowing water volumes and the surface area of the wetland. The calculation is based on high-resolution elevation data and measured or modeled runoff. In the second step, using export coefficients, the nutrient load to each wetland is calculated based on the catchment's land use and soil type distribution. Finally, nitrogen and phosphorus retention is calculated based on the calculated loads in step 2.

The model results can be used to quickly find out the potential nutrient retention in a proposed wetland, as well as to get an estimation of the wetland size needed to enable optimal nutrient retention.

In 2025, we calculated the wetlands' potential effects on nutrient reductions for all of Sweden and presented them as a StoryMap. 

Additional results from the calculations are listed on the page Rätt åtgärd på rätt plats.

References

Djodjic, F., Geranmayeh, P. & Markensten, H. 2020. Optimizing placement of constructed wetlands at landscape scale in order to reduce phosphorus losses. Ambio 49, 1797–1807. 

Djodjic, F., P. Geranmayeh, D. Collentine, H. Markensten, M. Futter. 2022. Cost effectiveness of nutrient retention in constructed wetlands at a landscape level. Journal of Environmental Management, Volume 324, 2022, 116325.