Stable foams and sludge bulking: The largest remaining problems (abridged)- Discussion

The separation of activated sludge in secondary settling tanks is the cruci al step in biological wastewater treatment from the point of view of both f inal effluent quality and operation of the aeration plant. The sludge-separ ation problems of bulking and foaming are connected with an excessive growt h of filamentous micro-organisms in the biocenosis of activated sludge. This paper (a) describes the methods which are used for the quantification of activated-sludge separation problems, and (b) summarizes the design reco mmendations for bulking and foaming control.