Control of Activated Sludge Filamentous Bulking – IV. Effect of Sludge Regeneration

Abstract

In addition to the previously published growth theory based on the relation of μ^ to ks , the paper deals with an accumulation-regeneration theory of microorganisms selection. The accumulation-regeneration phenomenon can play a role in population dynamics only in the systems where the accumulated substrate can be subsequently oxidized and thus the accumulation capacity restored in one feeding cycle. This condition can be realized in properly designed systems with the substrate concentration gradient along the reactor. As a criterion of accumulation capacity restoration it is suggested to use the oxidized proportion of the substrate removed in one feeding cycle. Extensive laboratory experiments have shown a significant relation between the SVI and the percentage of the substrate oxidized. Practical consequences of these findings for the control of filamentous activated sludge bulking are also discussed in the present paper.