| 摘要 |
<p>PURPOSE:To overcome a difficulty in separating a liq. mixture of raw water and activated sludge into activated sludge and treated liq. in a settling tank after aeration by judging whether the sludge in the liq. mixture is easily floated or not in the settling tank and preventing the floating of the sludge. CONSTITUTION:Raw water is introduced into an aeration tank 1 and mixed with activated sludge, and the mixture is aerated by a blower 2 through an air diffuser pipe 3. The aerated raw water is separated by settling into activated sludge 7 and supernatant water (treated water) in the final settling basin 6, a part of the activated sludge 7 is returned to the aeration tank 1 by a pump 8, and the remainder is discharged outside the device as excess sludge by a pump 9. In this case, whether sludge in the liq. mixture is easily floated or not in the settling basin 6 is judged based on the oxygen utilization rate due to a denitrification reaction in the liq. mixture and the value obtained by subtracting the oxygen utilization rate from the total oxygen utilization rate in the liq. mixture, the activated sludge in the settling basin 6 is returned when 'YES', and the flotation of the sludge is prevented.</p> |
