Nitrification of digestate

Transforming Biogas Digestate into Nitrate-Rich Fertilizer: A CuttingEdge Sustainable Solution to Significantly both Reduce Agricultural GHG Emissions and Increase Crop Yields.

PROJECT INFO:

DURATION
2025-2027
 
FUNDING:
Innovation Fund Denmark
 
TOTAL BUDGET: 5.564.032,00 DKK
 

PARTNERS:
Advanced Substrate Technologies
Aarhus University (BCE)
Rybjerg Biogas P/S,
Dangrow Agro A/S
A/S Knud Jepsen
Ny Vraa ApS

 

CHALLENGE

Ammonia loss emissions

TECHNOLOGY

Automated nitrification process

POTENTIAL

Higher yield potential

Goal

  • Agriculture: Cut GHG, Boost Yield via nitrification of Biogas Digestate
  • Demonstrate nitrification of digestate converts ammonium to a nitrate fertilizer
  • Validate elimination of ammonia evaporation and indirect N₂O emissions from nitrate fertilizer
  • Prove 20% increased crop yields through more efficient plant uptake of nitrogen and sulfate
  • Quantify scalability and sector climate impact for agriculture by 2030
     

Plan

  • Run continuous, automated nitrification on digestate at Rybjerg Biogas to confirm stable ammonium → nitrate conversion at two 10 m³ tanks.
  • Optimize oxygen dissolution, foam control, pH regulation, and dry-matter removal using improved MBBR tank design and efficient O₂ dissolving methods.
  • Produce 3 nitrate fertilizer products (NO₃, PKNO₃, +50 NO₃-N) for agronomic tests.
  • Measure nutrient/carbon mass balances, quantify GHG impact, validate economics, and present results to agriculture and biogas stakeholders to prove scalability and 2030 climate potential.
     

Expected results

  • 200 L/h throughput with >95% NH₄→NO₃ conversion over continuous automated operation
  • Prove near-zero ammonia evaporation and reduced indirect N₂O from the nitrate fertilizer
  • 25% higher grass yields and nitrogen-use efficiency from nitrate fertilizer vs untreated digestate
  • Verified climate impact, if the technology is used at biogas digestate in agriculture by 2030
PARTNERS:
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The project is part of the Mission Partnership, and the funding is provided by Innovation Fund Denmark.

We continuously open new calls and programmes that support innovation within food and bioresources.

Mette Kallestrup Spring

Mette Kallestrup Spring

Program Manager (mission partnership)

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