Takashi SAKAMAKI
Development of technology to produce calcium phosphate fertilizer out of sewage sludge incineration ash to realize the construction of phosphorus circulation system
Shuji HIMENO , Toshiya KOMATSU
Recently, there has been a concern about the depletion of the phosphorus ore on the world scale.
In this research, we focused on the alkali extraction + Ca method to produce the calcium phosphate fertilizer out of the sewage sludge incineration ash.
Compared to other technologies, this method requires less medicinal substances and energy to obtain the phosphoric acid calcium.
In this research, we studied the requirements of producing the calcium phosphate fertilizer and carried out a cultural test on farm products to confirm its effectiveness as the phosphorus fertilizer.
The result showed that the content rate of C-P2O5 in the calcium phosphate became as low as 21.2wt% when that of T-P2O5 in the sewage sludge incineration ash was low.
Moreover, it has been understood that the calcium phosphate can be substituted for the phosphorus ore to produce the calcium superphosphate.
However, it has to be noted that the additive rate needs to be lowered so that the unreacted Ca(OH)2 does not remain in the calcium phosphate and the standards for the calcium superphosphate fertilizer will be surely met.
In addition, the technology will be required from now on to lower the content rate of Al which is the obstructive element.
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