| 摘要 |
PURPOSE:To considerably decrease diluting water, eliminate the need for final settling basins and sludge return and obviate the occurrence of bulking by the removal of PO4 through addition of Mg compound and the mechanical dehydration through addition of a cationic high polymer flocculant. CONSTITUTION:Raw liquid 1 contg. BOD, NH3-N, PO4 such as crude night soil is flowed into an aerating tank 4 without being diluted or if it is to be diluted unavoidably for the purpose of defoaming or the like, after it is diluted to less than about 6 times without being diluted to more than this. In this aerating tank 4, an air lift pipe 3 or the like is provided and granular solids 2 such as sand are suspending and flowing in the tank. At this time, a magnesium compound 14 such as magnesium oxide or both of this and phosphoric acid or phosphoric acid compound are added to the raw liquid 1 or the liquid in the aerating tank 4, whereby the liquid is treated. The effluent 6 having been removed of BOD and NH3-N, PO4 by biological and chemical reaction is separated of granular microbe attached solids in a sedimentation separating part 5, after which it is flowed into a storage tank 7, thence it is added with a cationic high polymer flocculant 17 in a mixing tank 11, whereby it is flocculated. The treated liquid is subjected to solid-liquid separation by a centrifugal dehydrator 8. |
