2001 年 13 巻 3 号 p. 163-166
Incinerated ashes of sewage treatment sludge contain significant amount of phosphorus. Phosphorus is a very important material, and studies on phosphorus recovering technology are going under way. However, the phosphorus recovered from this sludge is mainly composed of aluminum phosphate. To promote the utilization of aluminum phosphate, zeolite formation process was studied. On the run 1, phosphorus recovered from incinerated ash of sewage treatment sludge by using H2SO4 and NaHCO3 was treated with NaOH, which dissolves aluminum phosphate and extracted aluminum phosphate reacted with aqueous sodium silicate solution to form zeolite. In this reaction, zeolite was recovered by freezing treatment followed by recovering of Na3PO4 by vaporization. On the run 2, phosphorus recovered by using of sulfuric acid and calcium carbonate was treated with NaOH in the same way as run 1. Aluminum phosphate reacted with calcium sulfate by alkalization formed calcium phosphate. Phosphorus free aluminum reacted with sodium silicate to form zeolite, and Na2SO4. Recovered zeolite showed the methylene blue adsorption capacity of 90mg (methylene blue)/g.