Fig. 3 shows the improvement in TP and NH3-N removal in four
compartments. After augmentation with PDB, the removal of TP
was significantly improved in the compartment 1 and 2, with effi-
ciencies from 30.4% to 41.2% and 21.6% to 27%, respectively. Meanwhile,
NH3-N removal in compartment 3 and 4 increased from 1.3%
to 12.8% and 2.2% to 2.8%, respectively, implying gradual accumulation
of ammonia oxidation bacteria (AOB). In previous reports,
the ammonia nitrogen process was extremely sensitive to phenolic
compounds (Amor et al., 2005). With TP removed ahead, the followed-up
compartments were loaded with harmless inlet, which
is favorable for ammonia nitrogen removal.