Improving bone-based phosphate fertilizer by pyrolysis.

Phosphorus is a macronutrient for all organisms, and its projected future scarcity generates a need for more efficient P recycling technologies. Because animal bones are rich in P, they could be employed to recycle part of P fertilizer inputs in agriculture, while diminishing environmental issues and health risks associated with cadmium in phosphate rock-based fertilizers. Moreover, pyrolysis is an alternative treatment to calcination that could both eliminate disease sources from bones and generate an efficient fertilizer ("bone char"). Our aim was to evaluate the physical and chemical characteristics of P in pyrolized pig bones as affected by temperature (400, 550 and 800 °C) and atmospheric conditions (sealed chamber, purging with N2, or steam activation)