HoSt Realises: Biomethane and Organic Fertilizer from Manure in Sint-Oedenrode, Netherlands
In Sint-Oedenrode, province of North Brabant in the Netherlands, 1 million Nm3 (cubic meter) of biomethane per year will soon be produced for supply to the gas network, sufficient for approximately 750 households. For this purpose, 40,000 tons of cattle manure is anaerobic digested from several dairy farms in a HoSt biogas installation. In addition, the digested manure is processed into an organic fertiliser.
The fresh manure originates from both Van Genugten dairy farm in Sint-Oedenrode and several nearby dairy farms. “This project is a great example of regional cooperation resulting in energy production, emission reduction and a closed manure loop,” says Sjaak Klein Gunnewiek, sales manager of biogas projects at HoSt. In addition to sustainable energy production, in this project – GroeneWoudGas – manure is processed into tailor-made products for fertilising the forage crops. Above all, CO2, methane and nitrogen emissions are maximally reduced at company level thanks to 100% manure digestion.
Manure valorisation to organic fertilizer
The recovery of fertiliser concentrate from the digested manure starts with the hygienisation of the digestate, the fertilising product that results from the digestion process. Thanks to hygienisation, any germs are slain and the digestate is made export worthy. This makes it possible to fulfill the duty of manure processing. A centrifuge separates the digestate into a thick fraction and a thin fraction (liquid manure), after which a nitrogen stripper extracts nitrogen from the thin fraction. The thin fraction with valuable potash fertilizers can then be used by the livestock farmers for organic fertilisation.
The remaining product from the stripper is nitrogen-rich ammonium sulfate, which is usable in liquid form or can be crystallised. This product is expected to be recognized by the European Union as a fertiliser substitute from 2021 onwards, but can already be used within the pilot mineral concentrate in which the project is participating. “To close the regional loop, we will use this product on the grassland of our customers, among other things. Knowledge partners supervise use in practice and conduct field trials, “says initiator Van Genugten.