Effect of aeration modes on nitrogen removal and N 2 O emission in the partial nitrification and denitrification process for landfill leachate treatment.

The anoxic/multi-aerobic process is widely applied for treating landfill leachate with low carbon to nitrogen ratio. In this study, the effect of two aeration modes in the aerobic phase, i.e. decreasing dissolved oxygen (DO) and increasing DO, on nitrogen removal and N ₂ O emission in the process were systematically compared. The results demonstrate that the aerobic phase with increasing DO mode has a positive effect on improved total nitrogen removal (78 %) under the COD/N ratio as low as 3.45 and minimized N ₂ O emission. DO concentration higher than 1.5 mg/L in the aerobic phase reduced nitrogen removal and led to a significant high N ₂ O emission in the process. Complete nitrite denitrification in the anoxic phase correlated with minimized N ₂ O emission. Under efficient nitrogen removal stage, N ₂ O emission factor was 2.4 ± 1.0 % of the total incoming nitrogen. Microbial analysis revealed that increasing DO mode increased the abundance of ammonia oxidizing bacteria and denitrifiers.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2022 Elsevier B.V. All rights reserved.)