Superior fertiliser products

Currently, the biogas and manure processing sector in Flanders faces some major challenges: tightened environmental legislation, increasing fertiliser pressure, etc. The Flemish fertiliser surplus must be processed in a judicious and sustainable way.

By recovering nutrients (plant nutrients) from animal waste and biomass (residual) streams instead of destroying them, we can close cycles and create a more circular economy. Although this is a spearhead objective for Flanders, the sector has so far come up against obstacles in the areas of technology, legislation, profitability, etc.

With the NPirriK project, the manure processing company Arbio BVBA is working on a technologically innovative solution.

Every year, we ferment 90,000 tonnes of manure with organic material. This process results in biogases and a raw residual product, separated into a thick and a thin fraction. The thin, watery fraction does not contain as much organic matter and is rich in nitrogen (N) and salts. The thicker, drier fraction still contains a lot of organic matter and phosphorus (P), and is pressed into new fertiliser granules.

The NPirriK project involves a new processing technique for this thin fraction. It is separated into a concentrate rich in nitrogen and salts on the one hand, and a low-salt permeate (filtered water) on the other. The concentrate is added to the thick fraction, with which we can make richer fertiliser pellets. The filtered permeate, now low in salts and nitrogen, can be used as irrigation water on surrounding agricultural plots.

NPirriK is thus fully part of that more circular vision: with manure and biomass waste flows from local agriculture, we can optimally recycle valuable raw materials and water and use them again locally. In this way, we also contribute to the replacement of scarce raw materials.

Moreover, with this innovative project, unique in Europe, we are putting Flanders even more strongly on the map as a trendsetter in the field of fertiliser processing and nutrient recovery, which will also translate into economic terms.

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Arbio BVBA

Partners Turbin, Agri-fert, Bodemkundige Dienst van België, Dorset GM





  1. We have found a solution to reprocess the (not so coveted) concentrate of nitrogen and salts from the aqueous fraction and add it to the dry fraction. It even costs us less energy to recover that nitrogen than to destroy it by the traditional method.
  2. Thanks to the new processing technique, we get dried fertiliser pellets with a higher nitrogen to phosphorus ratio. These pellets ensure better plant growth and better meet the needs of gardeners and farmers. Moreover, they can be used more widely in the increasingly strict framework of fertilisation standards.
  3. The water released by the new technique is low in nitrogen and salts and can serve as irrigation water for local agricultural crops. This is interesting, especially in times of persistent dryness in Flanders, because it can limit the use of expensive surface water and groundwater reserves.
  4. The number of transport movements required from the processing plant is drastically reduced. By an extra pressing we obtain a less watery fraction, with a lower weight and volume and thus better manageability.


  1. Good cooperation between different partners is crucial for innovation. The partnership between producers, technology suppliers and researchers has certainly led to better end results in the different work packages within this project.
  2. We should not underestimate the importance of dissemination. Articles in the trade press, websites, various Facebook pages, innovation competitions, presentations at international conferences, etc. have all helped to make our project more widely known.
  3. It takes a lot of time to fully develop such an innovative project. The duration of the Flanders Circular project (15 months) was too short for us to make agreements with the technology suppliers, install the new technologies and fully automate the entire process. Also, adjusting the new manure pellets to the wishes of the buying parties will still take time.
  4. The good cooperation between the various sectors and stakeholders in this project means great added value in terms of innovation. The use of labour care and social economy also provides room for creative designs and working methods that would not be possible in a traditional way.
2 to 3X more nitrogen and phosphorus in manure pellets
2X higher sales value for fertiliser pellets
700.000 tonnes tackling nitrogen loss in Flanders


We can conclude that our project is successful. In the classic processing of manure and biomass (residual) flows in Flanders, too much energy is still spent on removing the nitrogen instead of reusing it. This amounts to an annual loss of 700,000 tonnes of nitrogen, and that while Flanders still imports mineral nitrogen from outside the EU. By reusing as much of that nitrogen as possible, we also have to import much less. Moreover, in time, our concept would be equally applicable to other types of fertiliser processing. Recovering and locally reusing nutrients instead of eliminating them is truly the circular future.

The aspect of irrigation water also certainly deserves further follow-up, since agriculture in Flanders is increasingly having to deal with longer periods of dryness.

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