| 摘要 |
PROBLEM TO BE SOLVED: To produce a specified quantity of iron ion-containing solution in a short time by mixing iron powder having a specified average particle size with a solution being not less than saturated concentration in a dissolved oxygen quantity, allowing the iron powders to react with the dissolved oxygen, and producing a solution containing the iron ions. SOLUTION: The iron ion-containing solution is added to waste water containing phosphorus to remove the phosphorus in the waste water. This iron ion-containing solution is produced by mixing the iron powder having 100-300μm average particle sizes with the solution being not less than saturated concentration in the concentration of the dissolved oxygen to allow the iron powder to react with the dissolved oxygen. A composition of the iron powder is preferred to be pure iron powder consisting of iron and inevitable impurities or alloy steel powder added with an alloy element. As preferred embodiment reduced iron powder obtained by reducing the mill scale with cokes and by pulverizing, atomized iron powder produced by a water atomizing method, electrolytic iron powder or pulverized cast iron, are listed.
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