Abstract:
Phosphorus is an important element not only for use in fertilizers, but also for the manufacture of industrial products. However, depletion of this resource is a problem. Japan relies on imports for the entire amount of phosphorus it consumes. For this reason, there is an urgent need to secure a stable supply of phosphorus. On the ohter hand, there is waste containg a considerable amount of phosphorus. On of them is sewage sludg ash, but it also contains many heavy metals, extraction of only phosphorus is difficult.