| 摘要 |
PROBLEM TO BE SOLVED: To provide a sewage treating device capable of suppressing the lowering of the removal of a phosphorus compound even when it is used for a long period. SOLUTION: In a sewage treating device, iron ion is generated by electrolysis to coagulate the phosphorus compound in the sewage. It is considered that the flocculation reaction is performed in 1:1 molar ratio of iron ion to phosphorus element in the phosphorus compound. Usually being controlled to 1.5 times of that of phosphorus element in the phosphorus compound, the molar ratio of iron ion is controlled to 3.0 times of that of phosphorus element in the phosphorus compound when the concentration of nitrate ion exceeds 100 mg/l and a coating film is started to be formed on an electrode.
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