| 摘要 |
<p>PURPOSE:To reduce the equipment capacity of a settling tank and to improve the quality of treated water by feeding a flocculating agent into sewage to accelerate the flocculatability of activated sludge in a biological treating stage of an activated sludge treating method for sewage or between the biological treating stage and the settling tank. CONSTITUTION:Sewage 1 is admitted together with return sludge 4 and the supernatant water 7 of a concentrating tank 6 into a biological treating stage 2, where the sewage is subjected to an activated sludge treatment; thereafter, the sewage is mixed with a polymer flocculating agent 11 which is fed in the rear part of the stage 2 and is then admitted into a settling tank 3. In the tank 3, the activated sludge in the inflow water forms large flocs which are settled and separated and are returned as return sludge 4 to the stage 2. Part of the sludge flows into the tank 6, and the supernantant water become the treated water 5 having low concn. of SS. The supernatant water 7 in the tank 6 is retuned and concd. sludge 8 is discharged into a sludge storage tank 9 to be treated in a sludge treating device 10.</p> |
