Fraunhofer Institute for Interfacial Engineering and Biotechnology IGBLiquid manure treatment and phosphorus recovery
In the EU-funded BioEcoSIM project, a concept was developed and verified in which a fertilizer containing phosphorus and potassium is recovered from manure by means of precipitation, which demonstrably enhances the properties of plants. The technology that the scientists developed was realized in a semi-technical installation. As part of the "PhosKa-Demo" project funded by the German Federal Ministry for Education and Research (BMBF), the process has now been further scaled up and tested in continuous operation.
A mobile, fully automated plant with a throughput of 1 m3/h raw liquid manure has been designed, constructed and installed. The core of the newly developed plant is a crystallization reactor which promotes the growth of the crystalline fertilizer for improved separation or formulation. The plant consists of a conditioning stage, a two-stage solid/liquid separation and downstream crystallization or precipitation. After commissioning, the system was tested and further optimized in continuous operation on the premises of a potential user, an agricultural farm with livestock farming.
With this process, more than 90 percent of the phosphorus contained in the liquid manure can be recovered as fertilizer salt. In addition, the combination with low-energy and robust solid-liquid separation produces an organic fraction low in nutrients that can be used as a soil conditioner.
In this project, the quality and effectiveness of fertilization by the recovered fertilizer salts – compared to mineral phosphorous fertilizers with similar phosphorus content – was also confirmed by greenhouse and field trials.
In another project, the plant will be followed by a stage for nitrogen recovery as ammonium sulfate. This makes the process suitable for the complete and efficient treatment of liquid manure.
