Concentrated Phosphorus Recovery from Food Grade Animal Bones

Disrupted nutrient recycling is a significant problem for Europe, while phosphorus and nitrogen are wasted instead of being used for plant nutrition. Mineral phosphate is a critical raw material, which may contain environmentally hazardous elements such as cadmium and uranium. Therefore, phosphorus recovery from agricultural and food industrial by-product streams is a critically important key priority. Phosphorus recovery from food grade animal bone by-products have been researched since 2002 and a specific zero emission autothermal carbonization system, called 3R, has been developed in economical industrial scale, providing the animal bone char product (ABC) as output. Different animal bone by-products were tested under different conditions at 400 kg/h throughput capacity in the continuously operated 3R system. Different material core treatment temperatures (between >300 °C and <850 °C) were combined with different residence times under industrial productive processing conditions. It was demonstrated that material core treatment temperature <850 °C with 20 min residence time is necessary to achieve high quality ABC with useful agronomic value. The output ABC product has concentrated >30% phosphorus pentoxide (P2O5), making it a high quality innovative fertilizer.