The initial COD and phenol concentrations obviously
influenced the COD removal. From the tests with the
increasing of COD, there were excessive substrate for the AS
culture resulting in decreasing in the COD treatment
efficiencies. During the tests with phenol, COD treatment
performance obviously decreased compared to one without
phenol. This is because phenol inhibited COD removal. This
situation also found in phenol-contaminated wastewater
treatment reported in prior works [2], [3].
2) Phenol removal
The phenol removal from the tests with the initial phenol
of 10 and 100 mg/L was shown in Fig. 3. From all tests,
phenol continuously decreased. At the end of the test, phenol
decreased for 21.94-97.50 and 0.28-14.19% from the tests
with the phenol concentrations of 10 and 100 mg/L,
respectively (Table II).