Substrate Composition

Aerobic granules can grow on a wide variety of organic substrates in sequencing batch reactor (SBR), including glucose, acetate, ethanol, phenol, particulate organic matter-rich wastewater, soybean-processing waste-water, and both simulated and real municipal wastewater (Morgenroth et al., 1997; Beun et al., 1999; Peng et al., 1999; Jiang et al., 2002; Tay et al., 2002a; Liu et al., 2003; Pan, 2003; Arrojo et al., 2004; Schwarzenbeck et al., 2004; Su and Yu, 2005), while nitrifying and phosphorus-accumulating granules have also been developed

Aqua Aerobic Granule

Microbial aggregates formed after 1-week operation of the reactor

Granular sludge formed after 2-week operation of the reactor

Microbial aggregates formed after 1-week operation of the reactor

Granular sludge formed after 2-week operation of the reactor

Mature granules appeared after 3-week operation of the reactor

Fig. 5.1. Aerobic granulation in the course of operation. Bar: 2 mm (Tay et al., 2001a).

Fig. 5.2. Microstructures of glucose-fed (a) and acetate-fed (b) aerobic granules (Tay et al., 2001a).

(Tay et al., 2002b; Lin et al., 2003; Tsuneda et al., 2004). Figure 5.2 shows that glucose-fed aerobic granules exhibited a filamentous structure, while acetate-fed aerobic granules had a non-filamentous and very compact bacterial structure in which a rod-like species predominated.

These seem to indicate that the formation of aerobic granules is a process independent of or insensitive to the characteristics of the feed wastewater, while evidence shows that the microbial structure and diversity of mature aerobic granules are closely related to the type of substrates used (Tay et al., 2001a, 2002b; Liu et al., 2003).

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