Phosphorus Recycling of Mixed Substances PROMISE
| Reference number | |
| Coordinator | Statens veterinärmedicinska anstalt |
| Funding from Vinnova | SEK 1 339 500 |
| Project duration | March 2014 - June 2017 |
| Status | Completed |
Important results from the project
A sustainable use of phosphor (P) must be based on recycling of P from organic waste to agriculture. The aim of the project was to evaluate the suitability of using digested residue in agriculture regarding the content of contaminants (heavy metals, medical residues and pathogens) and to evaluate treatment methods for safe recycling of P. The results may serve as a base for continued research and has been made available for decision makers and can be used for a more efficient P recycling and a reduced eutrophication in the Baltic Sea.
Expected long term effects
Treatment temperature is the most important factor for pathogen reduction during digestion, but other factors may also influence. Thermophilic digestion and pasteurization reduce pathogens in contrast to mesophilic digestion. Heavy metals and antibiotics remain nearly unaffected independent of digester temperature. Most contaminants can be eliminated through a thermo-chemical treatment. The results and a sample bank are available for further research and for decisions makers to promote better quality of recycled fertilizers and to enhance the use of valuable P-resources.
Approach and implementation
Samples were collected from 29 plants for digestion of mainly sewage sludge and manure in Finland, Germany and Sweden. The presence of contaminants was analysed and how treatment affected their presence. SVA were responsible for the microbiological analysis. Also, performed within the project was a laboratory study on reduction and regrowth of microorganisms comparing the influence from pasteurization before or after digestion and also a toxicological study with antibiotics.