The influent water in this study was simulated by tap water to
which the agents MnSO4H2O, (NH4)SO4, and NaNO2 had been
added. No microelements were added to the influent water since
they were already present in the tap water. The water solution
was prepared every other day. The water temperature, pH, and
the dissolved oxygen (DO) were not controlled during the operational
period of the biofilter. The tap water characteristics are
shown in Table 1.