| 摘要 |
<p>The treatment takes place successively in aeration, reaction and settling tanks with recycling of sludge from the settling tank. Part of the recycled, conc. sludge from the settling tank, part of the incoming waste water and a mixt. of waste water and sludge from the aeration tank are brought together in the reaction tank. The oxygen content of this mixt. in the reaction tank is measured and, if necessary, brought up to a required min. level and thoroughly agitated. From the reaction tank, the mixt. is advanced to the aeration tank for intensive purificn. and then to settling tank. After concn. most settled sludge is returned to the reaction tank. A fraction of the sludge together with part of the incoming waste water is fed into the aeration tank. A vertical cylindrical reaction tank is pref. surrounded by a coaxial, annular, aeration tank. Aeration of the reaction tank pref. takes place automatically as soon as the oxygen content of the liq. drops 0-0.2 mg/l.</p> |
