Patent ID: 6207054
Filing Date: 2001-03-27
Classification: C02F,Y02A,Y02W

Abstract:
A method of biologically cleaning polluted water by employing active sludge and at least three zones, of which at least one operates as a permanent biological treatment zone and at least two zones variably operate as a biological treatment zone and a clarifying zone, characterised in that (a) the variable zones are connected to the permanent biological treatment zone by means of a one way gate designated in such a way that flow created by the aerators in the variable zones can pass to the permanent biological treatment zone, whereas flow created by the aerators in the permanent biological treatment zone cannot pass to the variable zones; (b) the polluted water is constantly fed to a zone operating as a permanent biological treatment zone; (c) the aerators in this zone run continuously, and (d) during a period a back-mixing is carried out between said zone operating as a permanent biological treatment zone and a variable zone operating as a biological treatment zone, the latter zone operating as a clarifying zone during a previous period.