| 摘要 |
<p>PURPOSE:To facilitate the disposal of sewage with high efficiency even at a lowered air feed, in a sluge disposal process including steps of reaerating and returning sludge, by mixing the sewage with the returned sludge, subjecting the mixture to an anaerobic treatment, and then aerating the treated mixture. CONSTITUTION:Raw water 5 is introduced with returned sludge 6 into an anaerobic vessel 1, where the mixture is agitated gently and anaerobically treated for 15- 120min or so. In this case, the atmosphere may be maintained under a completely anaerobic condition, though it is not essential. the atmophere may be kept under a condition such that oxygen is not supplied positively. Consequently, the vessel 1 may be left open. A liquid in the vessel 1 is gradually introduced into an aeration vessel 2, where the liquid is aerated for 20-60min or so. The liquid in the vessel 2 is gradually introduced into a sedimentation vessel 3, where the liquid is separated into purified water 7 and active sludge 8 by solid-liquid separation. A part of the sludge 8 is fed to a reaeration vessel 4, where the sludge 8 is reaerated for 15- 120min or so, and returned as retured sludge 6. The remainder is discharged as excess sludge 9 outside the system.</p> |
