The relative abundance of the dominant genera identified in the system is shown in Table 3. The predominant genera in MHA, anoxic and oxic tanks were Anaerolineaceae and Sulfuritalea, Lactococcus and Blastocatella, and Saprospiraceae uncultured and Nitrosomonadaceae uncultured, respectively. Bacteria belonging to Xanthomonadales and Defluviicoccus were highly enriched in the total system. The bacterial composition of the sludge depends on the influent characteristics and operation conditions.