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North Europe’s largest biofilter test facility inaugurated

A large constructed wetland with biofilters was inaugurated at Gyldenholm Manor on the island of Zealand.

[Translate to English:] Deltagerne i indvielsen af det nye filtermatrice-anlæg hos Gyldenholm Gods var interesseret i at se, hvor vandet løb ind og ud, de forskellige måleenheder og selve bassinerne med flis. Foto: Janne Hansen


North Europe’s largest constructed wetland with biofilter was inaugurated at Gyldenholm Manor on the island of Zealand on June 14, 2018 by Torben Hansen, vice-chairman in the Danish Agriculture and Food Council. The inauguration took place in the presence of approximately 90 participants, including people from the authorities, advisory sector, commercial companies, agricultural organisations, agricultural schools and the research world. 

It was yet another dry and windy day in the weeks-long drought, but despite this, the participants were satisfied, because now even more knowledge in this important area will be forthcoming. The facility will be used for both research and testing with the aim of improving the efficiency of nitrogen reduction and phosphorous retention so that fewer nutrients from drain water end up in the aquatic environment. Researchers will also use the facility to investigate how any potential negative side effects can be minimised. 

Aarhus University, at the request of the Ministry of Food and the Environment, is responsible for the studies in a project, to which the ministry has granted an extra 15 million DKK. All told, the university is using 31 million DKK on studies regarding mini-wetlands with biofilters, of which 12 million DKK are funded by the Department of Agroecology and 4 million DKK are funded by research projects such as Future Cropping, BufferTech and iDræn. 

The constructed mini-wetland with biofilter project is led by Senior Researcher Finn Plauborg at the Department of Agroecology, Aarhus University, and is a collaboration between the Department of Agroecology and the Department of Bioscience.         

The test facility at Gyldenholm Manor has three basins with wood chips that contribute to removing nutrients from drain water from the 120 ha catchment area. Photo: Janne Hansen

Collective measures must be tested thoroughly

In order to reduce nutrient emissions from agriculture to the aquatic environment, it is necessary to use a range of measures. Some of these, for example catch crops, are used in the cultivated fields, but there is also a need for collective measures outside the cultivated land. However, more knowledge is necessary about potential collective measures outside the cultivated fields. Mini-wetlands with biofilters are one of the possibilities.   

The new test facility will help researchers and agriculture to shed light on whether it is an efficient and economical way to remove unwanted nutrients from field drain water. 

- Mini-wetlands without biofilters are now approved as a measure to which you can apply for subsidies, but they require more land to remove the nutrients from drain water than constructed wetlands with biofilters. The latter only needs to take up one quarter of a hectare to remove nutrients from drain water from 100 hectares, said Finn Plauborg at the inauguration. He added:    

- Before we researchers can permit ourselves to recommend the ministry that a mini-wetland with biofilter can be considered a viable collective measure on a national scale, we need more research-based figures that demonstrate the efficiency, costs and durability of the facility under various geographical, hydraulic and weather conditions. 

More research facilities underway

The facility at Gyldenholm Manor is the first in the project. There are three basins with wood chips to help remove nutrients from drain water from 120 hectares – although not from all the drain water because that would require five basins and for financial reasons the project has only established three. 

Water flow is measured on a continual basis and data are sent electronically directly from the field to the researchers. Water samples are taken regularly, and they are analysed for a series of substances, including nitrogen and phosphorous. The preliminary figures indicate that the facility removes about 80 percent of the nitrogen from the drain water from the 120 hectares catchment area. 


The representative for Danish agriculture was quite satisfied.


- We need to get drain measures on board, and I am pleased that visible results are forthcoming. We need many more tools and smart solutions to meet the challenges outside the cultivated fields. We cannot live with more restrictions in our cultivated fields, said the Danish Agriculture and Food Council vice-chairman, Torben Hansen, just before he cut the green ribbon and inaugurated the new, large constructed mini-wetland with biofilter test facility. 

Vice-chairman in the Danish Agriculture and Food Council, Torben Hansen, cut the ribbon to the new facility. He was pleased that concrete figures concerning yet another potential environmental measure will soon be forthcoming. Photo: Janne Hansen


Facilities will also be established in Spjald, Vindum, Haderslev, at Hofmansgave on North Funen, and in Ringe, so the researchers can carry out studies under various physical conditions. In addition, a semi-field test facility will be established at AU Foulum, where the efficiency of various kinds of wood chips and the possibility of including microorganisms to improve nitrogen reduction during the winter months will be investigated.

You can also read the article Development of mini-wetlands with biofilters enters new phase.



For more information please contact

Senior researcher Finn Plauborg, Department of Agroecology

Email: finn.plauborg@agro.au.dk

Telephone: +45 8715 7714

Mobile: 2218 1809