| 摘要 |
PURPOSE:To prevent deterioration of activated sludge during suspension of operation for a long period by feeding back supernatant liquid in a settling tank to an adjusting tank and charging a carbon source material for cultivating bacteria in the activated sludge to at least one of the adjusting tank or an aeration tank. CONSTITUTION:When water level of an adjusting tank 1 is descended because of suspension of flowing out of filthy water from a filthy water pipe 2 by the reason of holiday, etc. a signal concerning the information is outputted by a level sensor 13; controllers 19, 20 operate basing on the signal to close a solenoid valve 15 of a waste water pipe 14 and to open a solenoid valve 18 of a nutrient liquid tank 17. Thus, the level of each tank is held at an almost constant level, and carbonaceous components such as methanol, ethanol, and nitrogenous components such as urea, ammonium sulfate, are replenished always from the nutrient liq. tank 17. Therefore, the same ambient condition as in the stage of feeding the filthy water is maintained for bacteria in the activated sludge.
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