Effect of dissolved oxygen on heterotrophic denitrification using poly(butylene succinate) as the carbon source and biofilm carrier

The effect of dissolved oxygen (DO) on heterotrophic denitrification using poly(butylene succinate) as the carbon source and biofilm carrier was evaluated in a lab-scale experiment. Aerated, low-oxygen, and anoxic treatment groups were set up, which had average DO concentrations of 5.2 ± 1.0, 1.4 ± 1.2, and 0.5 ± 0.3 mg L−1, respectively. The NO3−-N and total nitrogen (TN) removal rates in the aerated group (37.44 ± 0.24 and 36.24 ± 0.48 g m−3 d−1, respectively) were higher than those in the other two groups. There was no significant difference between the low-oxygen and anoxic groups for the NO3−-N or TN removal rate. Accumulation of NO2−-N reached 5.0 mg L−1 in the aerated group; no nitrite accumulation was found in the other two treatment groups. Bacterial communities of the low-oxygen and anoxic groups showed high similarity and were significantly different from those of the aerated group.