With a nitrogen stripper it is possible to reduce nitrogen emissions. With this method, nitrogen is stripped from digestate and stored as ammonium sulfate or nitrate. A nitrogen stripper is a technical installation that extracts the nitrogen from animal manure and fixes it in a raw material for fertilizer. This means that the nitrogen from the animal manure can no longer escape into the air from storage or when it is applied to the land. The N-stripper has therefore been developed for farmers with a large manure surplus. 

The nitrogen problem is the harmful consequence for ecosystems of an excess of emissions of reactive nitrogen compounds in the nitrogen cycle due to human actions. With an N-recovery unit it is possible to reduce nitrogen emissions at company level. On many farms, manure is removed because the placement space does not allow this amount to be spread on their own land. In many cases nitrogen is the limiting factor. In many cases chemical fertilizers are purchased after the manure has been removed.

One possibility to spread more animal manure on own land is to oxidize the nitrogen through a “biological treatment”. However, this costs a lot of energy and the valuable nitrogen is lost from the farm.