Waste water treating apparatus

A waste water treating apparatus for treating waste water including an organic material, comprising:

• a downward flow chamber (2) disposed to extend in the depth direction for allowing a downward flow of a mixed liquor comprising said waste water to be treated and an activated sludge, an upward flow chamber (4) disposed in the depth direction outside and adjacent to said downward flow chamber for allowing an upward flow of said mixed liquor to be supplied through said downward flow chamber, circulation means (8) for circulating said mixed liquor through said upward flow chamber and through said downward flow chamber by raising said mixed liquor from said upward flow chamber to said downward flow chamber, gas supply means (16) for supplying an oxygen containing gas into said downward flow chamber, organic loading representing information providing means (28) operatively coupled to at least one of said upward flow chamber and said downward flow chamber for providing information associated with an organic loading of said waste water, first controlling means (16a, 100) responsive to said information from said organic loading representing information providing means (28) for controlling said oxygen containing gas supply means (16) so that a controlled quantity of supplied oxygen containing gas is the quantity necessary for treating said organic loading of the waste water in accordance with said organic loading associated information, and second controlling means (8a, 100) responsive to said controlled quantity of supplied oxygen containing gas for controlling said mixed liquor circulation means (8) so that the circulation flow rate of said mixed liquor is suitable for treatment by said controlled quantity of supplied oxygen containing gas.