A biokinetic model which includes a flocforming and three common filamentous microorganisms (Sphaerotilus natans, Type 021N, Type 0961) is introduced. With this competition model which accords with a variety of experimental observations, different bulking phenomena are explained. It is demonstrated that not only the well known facts such as reactor configuration, readily biodegradable substrate and temperature exert a strong influence on bulking behaviour, but also the influent slowly biodegradable substrate as well as inoculating biomass. Therefore it can be concluded that the performance of primary settling tanks plays an important part in bulking.

Activated sludge process, Bulking, Population dynamics, Mathematical modelling, Flocforming organisms, Filamentous organisms, Sphaerotilus natans
This content is only available as a PDF.
© IWA Publishing 1992
You do not currently have access to this content.