Waste water purificn. by activated sludge process - comprises operating a pretreatment tank as redox tank and controlling oxygen supply

摘要

Activated sludge process waste water purificn. plant comprises (i) a pre-treatment tank, (2), behind a settling tank with final automatic purificn., (1), (ii) an oxidn. tank, (3) contg. >=1 aeration device, (4), in which sludge flakes are kept in flotation, (iii) final clarifying tank and (iv) sludge recycle from final clarifying tank to oxidn. tank. The pretreatment tank also contains an aeration device in which the water to be purified undergoes a partial degradation of the BOD5-value. The oxidn. tank is also laid out as a sludge consumption tank. Novelty consists in designing the pre-treatment tank (2) as a redox tank for a sludge content of 0.05-0.8 (0.08-0.15) dry solids/m3, for a space load of 0.1-1.5 (0.15-0.35) kg BOD5/m3. day and adjusting an O2 load of 0.02-0.2 (0.05-0.1) kg O2/kg BOD5 in redox tank (2). Total degradation can reach 96-98%.