| 摘要 |
PURPOSE:To improve the settling and enriching properties of activated sludge by stopping feeding of liquid to aerobic and anaerobic treating tanks when the water level in the anaerobic treating attains to a prescribed level and restarting the feeding after sepn. of the activated sludge in the aerobic treating tank. CONSTITUTION:The liquid in the treating tank A in which an anaerobic atmosphere is maintained is fed to the treating tank B in which the aerobic atmosphere is maintained to aerate said liquid; at the same time the liquid is returned from the tank B to the tank A in the stage of treating the waste water in the tank A and the tank B. The feeding of the liquid to the tank B, the aeration in the tank B and the return of the liquid to the tank A are stopped when the water level in the tank A attains to the prescribed level. The activated sludge in the tank B is then separated and the separated water and a part of the separated sludge are discharged to the outside of the system. The feeding of the liquid to the tank B, the aeration and the return of the liquid to the tank A are thereafter restarted. Nitrogen and phosphorus in addition to BOD are removed in the above-mentioned way, by which the settling and enriching properties of the activated sludge are improved as well.
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