| 摘要 |
PURPOSE:To reduce the output of excess sludge and to prevent bulking and rising by dissolving air in the liq. mixture in an aeration tank under pressure, depressurizing the liq. mixture to atmospheric pressure to generate air bubbles in the liq. mixture, and separating sludge and treated water. CONSTITUTION:The liq. mixture treated in a high-concn. aeration tank 2 and contg. 8,000-20,000ppm sludge is sent into a pressurization tank 4 by a booster pump 3, compressed air sent from a compressor 5 is dissolved, the mixture is sent to a forced separation tank 6 and depressurized to atmospheric pressure to generate air bubbles, sludge is floated up, and solid and liq. are separated. The treated water is sent to a low-concn. aeration tank 7, aerated, and then sent to a settling tank 8. A requisite amt. of the floated activated sludge is returned to the high-concn. aeration tank 2 through a return pump 9, and reused. By this method, the sludge is aerated at high concn., and the generation of excess sludge is reduced. In addition, since the second aeration tank 7 for enhancing the clarity of treated water is operated at low. concn., bulking and rising can be easily prevented.
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