| 摘要 |
PURPOSE:To prevent the thickening of the materials treated by a membrane so as to stabilize the treatment and to improve the quality of treated water by providing flocculating and dehydrating means, biological treating means, membrane separating means, flocculation treatment means and excess sludge returning means, etc. CONSTITUTION:Night soil sanitary sewage is flocculated and dehydrated by a flocculating tank 1 and dehydrating means A and the separated water from the means A is biologically treated by the means 5 consisting of a nitrifying and denitrifying tank, etc. The treated liquid subjected to the biological treatment is subjected to a membrane sepn. by an ultrafilter membrane separating means 7. The excess sludge in the system is further flocculated by an inorg. flocculating agent (e.g., alum) from the means 21 and the flocculated excess sludge is returned by the means 20 to the flocculating tank 1. As a result, the thickening of the materials removed by the membrane is prevented, by which the treatment is stabilized and the quality of the treated water is improved. |
