ABSTRACT
This chapter offers information about the internal structure of aerobic granules in terms of the distributions of the microbial cells, polysaccharides, and cell surface hydrophobicity. An aerobic granule cultivated in an acetate-fed sequencing batch reactor was sliced and its internal structure was visualized by imagine analysis technique. Porosity of biofilm or anaerobic granules can facilitate nutrient transfer. The heterogeneous structure of aerobic granules indicates an uneven distribution of biomass. Cell surface hydrophobicity has been regarded as a trigger of aerobic granulation. After the formation of the aerobic granule, the primary trigger function of cell surface hydrophobicity may become secondarily important, but cell surface hydrophobicity may continue to play a part in the stability of the aerobic granule structure. The structure of an aerobic granule is related to its size, that is, a small granule has a relatively homogeneous structure, whereas a heterogeneous structure was observed in large aerobic granules.
