Test ponds in KWR garden come to life – Solids Rotterdam
Test ponds in KWR garden come to life
KWR Water Research Institute

Test ponds in KWR garden come to life

Experiment with water treatment using wetland plants



The plants in the test ponds (“mesocosms”) in the KWR garden flourished in the first year. This gives use a good picture of water treatment, evapotranspiration from plants and biomass production at different flow rates.

In the second year of the VIP-NL research project “Wetland Plants on Water-Rich Peat”, we are investigating water quality and water balance in the cultivation of bullrush and reeds. That involves not only conducting field trials, but also using test ponds, because conditions can be controlled better in the latter. This approach makes the results more dependable.

Less algae growth
In early March, reed and bulrush rhizomes were planted in the test ponds. Some of them had already grown two metres tall after three months. Now, as the summer comes to an end, the test ponds are full of plants. As a result, there is less and less algae growth as the plants use the nutrients present and cast shade over the water. The evapotranspiration we measure varies considerably depending on the different plants.

Measuring the effects of flow rate
We pump simulated ditch water into the test ponds. That water consists of drinking water containing the nutrients nitrogen, phosphorus and potassium. We use three different flow rates for pumping. Those differences in flow rate affect both plant growth and the water treatment effect. When the dataset is complete, we will be able to draw further conclusions. The plants will be harvested in late September to determine differences in biomass. And anything we don’t need for further analysis can be reused beneficially as construction and insulation material!

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