| 摘要 |
A process for biological purification of waste water by the activated sludge method wherein the waste water is continuously passed through one or more treatment zones and a clarification zone, wherein the waste water treated in the last treatment zone at the outlet from the zone under suitable control of aeration and stirring is continuously divided into a predominantly aqueous fraction and a sludge-containing fraction, and wherein a portion of the sludge fraction is recirculated and mixed with non-treated waste water, of which the former is subjected to clarification, and the latter is recirculated to the same or a preceding treatment zone.
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