METHOD FOR RECOVERING PHOSPHORUS AND USING SAME AS FERTILIZER

摘要

[Problem] To recover phosphorus accumulated in a sewage-treatment plant or the like at a low cost in such a manner as to facilitate the utilization of the thus recovered phosphorus. To efficiently utilize the recovered phosphorus as a fertilizer. [Solution] Phosphorus in discharged water, which is a phosphorus source, is adsorbed by a phosphorus recovery material formed of an amorphous calcium silicate-based material and thus recovered. After adding the phosphorus recovery material to the discharged water that is a phosphorus source, it is preferred to adjust the pH value of the discharged water to 7.0 or higher. Also, it is preferred that the discharged water that is a phosphorus source is decarboxylated by reducing the pH value thereof to 6.0 or lower and then the phosphorus recovery material is added. As the phosphorus recovery material, an aggregate consisting of amorphous calcium silicate hydrate and Ca(OH)2 and having a Ca/Si molar ratio of 0.8-20 inclusive is preferred. The aggregate may be obtained by solid-liquid separation and drying. Alternatively, a slurry or paste containing the aggregate may be used. The recovered phosphorus recovery material can be used as a fertilizer.