| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a biological waste water treating device which is equipped with a carrier outflow preventive device for separating carriers without using a screen and is capable of drastically lessening maintenance and inspection and improving treatment efficiency. SOLUTION: The suspending activated sludge and carriers 24 which are entrained in a nitrifying liquid and flowing out into an accepting vessel 48 from a nitrifying vessel 26 are lowered by a descending flow passage 54 and is admitted into a separating chamber 56. The carriers 24 are settled and separated from the suspending activated sludge by utilizing the difference in the sp. gr. between the suspending activated sludge and the carriers 24 in the separating chamber 24. The carriers 24 settling on the bottom of the separating chamber 56 returns to the nitrifying vessel 26 by riding the flow of a water feed pipe 58 which takes-in the lower liquid in the separating chamber 56 and feeding the water to the nitrifying vessel 26. At this time, the flow of the water feed pipe 58 is formed by an air lift and, therefore, the destruction of the carriers 24 does not arise. Besides, the suspending activated sludge is returned to a denitrifying vessel by a nitrifying liquid circulating path 16 for circulating the upper layer liquid of the separating chamber 56 to the denitrifying vessel and is sent to a sludge settling vessel via a trough 70 for allowing the overflow of the treated water.</p> |
