floating natural filtration 

This floating natural filter is made up of a metal basket that is hung within a construction of floating, hollow, recycled concrete bodies. The metal basket is first lined with a coconut fibre mat and then filled with a substrate, like pebbles or expanded clay, which is subsequently covered with mainly reeds and other suitable hydrophytes. Within the filter, a biofilm naturally develops on the entire surface of the substrate as well as on the plants’ roots. The main filtration capacity is carried out by the biofilm, whereas the plants only filter a small amount of the nutrients. 

 Instead they are mainly responsible for forming air channels throughout the substrate with their roots. The filter absorbs nutrients, such as nitrogen and phosphorus, as well as organic carbon compounds, heavy metals and trace substances. These plant nutrients and ammonium are responsible for oxygen depletion in the waters and thus can cause a mass death of fish after an instance of heavy rainfall. Simultaneously, the submerged plants work as a floating wetland, cooling the environment through evapotranspiration and promoting biodiversity. The complete process of the combined elements follows the geometric shape of quarter circles, inspired by the idea of reimbursing the canal with its original, gently undulating shape. This shape supports the rejuvenation of the natural characteristics of the currently almost stock-still canal. The continuous filtration process is driven solely by gravity, as the water level in the filter is around 30cm above the waterbody. In dry seasons, the filter can be fed with river or canal water to achieve an even cleaner and healthier ecosystem.

Paulina Grebenstein 2019 

grebenstein@urbanedenlab.com 

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