| 摘要 |
<p>A sewage treatment plant has a settling tank 2 and a spherical holding tank 4. In the tank 2 sewage is allowed to settle, a clear aqueous layer 8 forming above a layer 10 of aqueous bacterial sludge. A stream of sludge is withdrawn from the layer 16 through the pipe 16 by a pump 14 and is mixed with a stream of incoming sewage for treatment supplied through pipe 6 and a stream of oxygenated sludge withdrawn from the holding tank 4 through a pipe 18. A major portion of the liquid leaving the pump 14 is introduced into an oxygenator 26 which includes a vertical pipe 34 in which downflowing sewage is contacted with bubbles of oxygen and which supplies oxygenated sewage to the holding tank 4. A minor portion of the liquid leaving the pump 4 is returned to the tank 2 via a pipe 22. <IMAGE></p> |
