To provide a method for recovering phosphorus from incineration ash of sewage sludge, in which the amount of an alkali source to be added to an aluminum-dissolved alkaline reaction solution is controlled adequately to prevent unnecessary expenses due to too much addition of the alkali source and defective extraction of phosphorus due to too little addition.
The method for recovering phosphorus from incineration ash of sewage sludge comprises the steps of: mixing incineration ash of sewage sludge with the alkaline reaction solution in a reaction tank to extract the phosphorus contained in incineration ash of sewage sludge in a liquid; separating the phosphorus-extracted liquid from the treated ash by solid-liquid separation: adding a calcium component to the separated phosphorus-extracted liquid; and withdrawing a calcium phosphate crystal from the calcium component-added phosphorus-extracted liquid. When aluminum is dissolved, the pH can not be controlled. But in this recovering method, the P alkalinity of the alkaline reaction solution to be supplied when a batch operation is performed or that of the liquid in the reaction tank when a continuous operation is performed is measured and phosphorus is extracted while controlling the amount of the alkali source to be added so that the measured P alkalinity is kept within a predetermined range.
COPYRIGHT: (C)2009,JPO&INPIT
Zenichi Kakefu
Norihisa Inoue
Torii Tetsuya
Tetsuya Yanase
Hirokazu Tsuboi
Hirokazu Ikeda
Gifu City
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Fumio Yamamoto