| 摘要 |
<p>PURPOSE:To previously remove suspended solids which are difficult to be decomposed by introducing raw sewage into a bioflocculating tank in which the oxidation/reduction potential is maintained at a specific value, allowing the sewage to stagnate therein for the specific period of time to flocculate and adsorb the suspended solids on sludge and sending the supernatant water to a regular treatment of the ensuing stage. CONSTITUTION:The raw sewage is received in a raw water tank 3 and is adjusted in water quality in this tank; thereafter, the sewage is supplied continuously by a raw water pump to the bioflocculating tank 1. Air is then blown into the tank by an air blowing nozzle 4 until the oxidation/reduction potential in the tank attains -50 to +100mV. The raw sewage is so supplied that the stagnation in the tank exceeds 45 minutes and is below 70 minutes. The thickened sludge is withdrawn by a returning pump 9 and is returned to the bioflocculating tank 1 when the suspended solids passing through the bottom of the bioflocculating tank 1 are increasingly thickened by thickening device 6 of a settling tank 2. The sludge is so returned that the sludge concn. of the bioflocculating tank attains 1.0 to 2.5g/l. The sludge is withdrawn by an excess sludge pump 8 and is discharged to the outside of the system by leaving a specified amt. when the excess sludge deposits in the setting tank 2.</p> |
