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Case Study #2
1 Project name

Growing Typha as Renewable Resource, Donaumoos, Germany
   
2 Keywords Typha, water purification, constructed wetlands, renewable raw material, mire conservation, landuse, Germany
3 Start of project 1998
4 End of project In operation
5 Address of contact person
Photo Bjoern Guterstam Dr. Ulrich Wild
Technische Universitaet Muenchen
Department of Ecology
Chair of Vegetation Ecology
D-85350 Freising
Germany
Tel. +49 8161 713715
Fax +49 8161 714143
Website: http://www.weihenstephan.de/vegoek/
Email: wild@weihenstephan.de
6 Short project description / project function The intensive agricultural use of groundwater fed mires (especially as arable land) leads to the loss of the peat soil. This involves the pollution of ground- and surface water with surplus nutrients as well as the atmosphere with climatic relevant gases (carbon dioxide, nitrous oxide). By means of the cultivation of Typha in constructed wetlands we intend
  1. to reduce the named pollutants to a great extent,
  2. to set peat growing processes going instead and therefore to reactivate the function of groundwater fed mires as matter sinks in the landscape,
  3. to make a contribution concerning the purification of flowing waters,
  4. to provide retention areas for surplus water and therefore to reduce the risk of flooding in the lower reaches of rivers and
  5. to provide a feasible alternative to the common landuse in lowland landscapes with a renewable raw material (suitable for the fabrication of insulating materials for building trade).
7 Summary of experiences Experimental design of the plant:
  • three constructed wetlands, total size 62'000m2
  • emergent macrophyte-based system with surface flow
  • source of water are two drainage canals, draining two agricultural watersheds
  • water pollution is effected by non-point sources
  • planting of 110'000 plantlets of Typha latifolia and T. angustifolia in May 1998

The Typha stands developed rapidly. In the second growing season (1999) shoot density increased and an average density of 70 shoots per m2 was reached for T. angustifolia and 45 shoots per m2 for T. latifolia.

Nutrient removal in the wetlands was high for NO3-N and PO4-P and low for organic N. In degraded peatlands (compared to wastewater), organic N seems to be bound in a more persistent form.

Weekly measurements of trace gas fluxes (nitrous oxide, methane) in the constructed wetlands and on a drained grassland (reference plot) were carried out. Cumulated nitrous oxide fluxes of the reference plot were significantly higher compared to the wetlands. For methane the situation was the other way around. Global warming potential (GWP) of one wetland was more favourable compared to the drained grassland, whereas a second wetland showed the highest GWP.
8 Project benefits Combination of use and restoration of an ecosystem. Establishment of a platform for the promotion of the ideas of Ecological Engineering in Germany. Proclamation of the concept to use wastewater as a resource and its disposal in the landscape.
9 Project level Pilot project
10 Financial scale Construction cost 210'000 USD (450'000DM), yearly management cost 14'000 USD (30'000 DM)
Financial support by: Deutsche Bundesstiftung Umwelt, Osnabrück
11 Environmental conditions Cold temperate climate, 48° Northern Latitude
12 Altitude 380 m above sea level
13 Description of special local conditions Located in the Donaumoos, Southern Germany, approximately 80 km north of Munich in the valley of the river Danube.
  Updated May 10, 2000