ABSTRACT
This chapter explores a microbial selection-based strategy for improving the stability of aerobic granules. Under hydrodynamic conditions, the growth of aerobic granules after the initial cell-to-cell attachment is the net result of interaction between bacterial growth and detachment, while the balance between growth and detachment processes in turn leads to an equilibrium or stable granule size. The nitrifying population grows much more slowly than heterotrophs, while the physical structure of nitrifying biofilms is much stronger than heterotrophic biofilms. Aerobic granulation is known as a microbial self-immobilization process that should be similar to the growth of biofilm. Heterotrophic bacteria growing on the slowly biodegradable storage polymers, such as poly-ß-hydroxybutyrate or glycogen, may have smaller growth rates as compared to those growing on easily biodegradable organic substrates. The selection and enrichment of slow-growing organisms, such as nitrifying bacteria, P-accumulation and glycogen-accumulating organisms, appears to be the most feasible engineering strategy.
