When constructed wetlands reach their performance limits, chemical oxygen demand (COD) rises above the permitted levels. But using a biochar/sand mix instead of a sand only filter can bring the COD back into compliance!

In collaboration with THREE C, a first prototype has been developed and successfully tested in the field by the Karlsruhe-based consulting engineers Roth & Partner.

Further tests will investigate whether an additional layer of biochar on an existing filter alone is sufficient to already improve the overall performance of the plant.

Either way, the use of biochar would be an excellent and cost-effective option for bringing overburdened constructed wetlands back into compliance.

For more information, please contact THREE C member Bernhard Schäfer: bschaefer@blinc-eu.org