| 摘要 |
<p>1406839 Biological purification process CELLULOSE ATTISHOLZ AG 8 Sept 1972 [23 Nov 1971] 41687/72 Heading C1C In an activated sludge process in a plant comprising, as a first stage, an aeration tank 1 and a settling tank 3 and, as a second stage, an aeration tank 6 and a settling tank 7, and in which nitrified liquid is recycled from the settling tank 7 to the first stage, the liquid fed to the first stage by supply line 12 and recycling line 17 is subjected to ammonification and denitrification, and the liquid fed to the second stage by line 5 and which is free of oxygen, is subjected to nitrification. The recycled liquid may be returned to tank 1 or 2, or conduit 2. Settled sludge is returned from tanks 3, 7 to tanks 1, 6 respectively by respective lines 13, 14. Floating sludge may be returned by line 19 from tank 3 to tank 1. The sludge discharged from tank 3 may be degassed and concentrated (e.g. by flotation). Aluminium and iron salts may be added through line 20 to remove phosphates. Flocculants such as bentonite and cellulose may be added to the second stage to aid settling.</p> |
