Decentralized processing of liquid manure

Research project with the Münster University of Applied Sciences

Decentralized processing of liquid manure

In this research project, the influence of slurry aging and separation efficiencies on dense central processing was investigated. Fresh pig slurry, cattle slurry and NaWaRo digestate were separated at the company Bioenergie Beerlage GmbH & Co.KG in Billerbeck and separated in two different settings with the Klass spiral filter. A nutrient analysis (N, P, K, MgO, CaO) was carried out and the biogas yields (according to VDI 4630 in a batch experiment) and a sum parameter (pH, conductivity, redox potentials) were investigated.

Results

pig manure

  • the biogas yield from raw manure halved after only 7 days of storage
  • The biogas yield of separated solids from pig slurry is independent of the age of the slurry
  • Phosphorus separation increases with slurry age and almost reaches the separation efficiency of a centrifuge with small size and power consumption (2.5 kWh/t raw slurry)

cattle manure

  • The biogas yield from raw manure is halved after only 7 days of storage
  • The biogas yield of the separated solids decreases with cattle slurry even with the age of slurry
  • Cattle manure should be separated as freshly as possible
  • Separation of nutrients is more difficult to achieve with cattle manure

digestates

  • The separation of digestate is primarily used for dewatering
  • Different degrees of humidity produce different types of infestation (beetles or fungi)
  • It is possible that the degree of degradation of the organic mass will increase (test results are still pending)

Products used