| 摘要 |
In a biological waste water purificn. process with at least one nitrifying zone, the waste water is reacted with recycle sludge contg. nitrifying microorganisms, with the supply of O2, to convert the Ncpds. in the waste water to nitrates. The sludge is sepd. in a subsequent zone, connected to the nitrifying zone, and recycled, at least partly, as recycle sludge, to the nitrifying zone. The novelty comprises retaining the sepd. recycle sludge in a separate ageing zone before recycling to the nitrifying zone, for a sufficiently long time to allow the growth of the nitrifying microorganisms. (a) The vol. of the ageing zone is proportioned for the prepn. of a total sludge age of at least 4-, esp. at least 7 days. (b) The sludge concn. in the ageing zone is at least 5 kg/cu.m., opt. reaching 20 kg/cu.m, and is higher than the sludge concn. in the nitrifying zone. (c) The amt. of O2 supplied to the sludge in the ageing zone is limited to that required for basic breathing.
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