NP-balans
Project overview
More related research
Short summary
The project increases the expertise to refine and use the digestate that arises in connection with biogas production. By adapting the nutrient content of the digestate for its intended use as fertilizer, its value can be increased.
Plant adapted fertilizers from biogas plants
The nutrient content in the digestate has been optimized by different techniques like co-digestion, recovery of phosphorous from reject water and digestate or by addition of nitrogen. The plant nutrient utilisation of optimized digestate was studied in field experiments and greenhouse experiments. We analysed plant biomass and nutrient content at harvest and compared with plants from unfertilized and mineral fertilized treatments.
Can we improve the nutrient balance in digestate before or after anaerobic digestion? We investigated:
- pre-treatment of organic substrates before digestion
- methane potential from co-digestion of different substrates
- phosphorous recycling by struvite precipitation from reject water and digestate
- optimize the nutrient balance by addition of struvite/ nitrogen rich substances to digestate
In forestry
Which are the long term effects of digestate in forest? In six 10-15 year old experiments, we investigated:
- Risk of leaching of nutrients and heavy metals
- Tree growth
In agriculture
What is the best form for digestate? Liquid or solid? How important is soil incorporation? What season is best for spreading? We investigated:
- uptake of nutrients and heavy metals in plants
- growth and harvest
- risk of leaching of nutrients
- risk of surface runoff of nutrients and heavy metals
The results will provide a basis for advice on how to use digestate to maximize the benefits and minimize the risks, with the goal to contribute to lowering of eutrophication in rivers, lakes and coastal areas.
This project is completed. It was a collaboration between Novia University of Applied Sciences (Vasa, Finland) and the former Department of Agricultural Research for Northern Sweden at the Swedish University of Agricultural Sciences (Umeå, Sweden).