| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method and a device for treating organic sewage, in which generated amount of excess sludge is remarkably reduced and stable removal of phosphorus is enabled at a high degree. SOLUTION: When activated sludge is returned to an aeration tank 3 after performing solid-liquid separation, a part of return sludge 20 is oxidized by ozone, solubilized and thereafter returned to the aeration tank 3. On one side, the other part of the return sludge 20 is retained in an anaerobic tank 5 and phosphate ions are discharged from sludge. Metallic ions 8 causing reaction for forming precipitate of phosphate ions are added to produce a phosphate compound. sludge in which the produced phosphate compound is removed is supplied to the aeration tank 3.</p> |
