Evaluation of denitrification performance and bacterial community of a sequencing batch reactor under intermittent aeration

Abstract

Effects of operational parameters (initial nitrite concentration, initial nitrate concentration, carbon source, and COD/N ratio) on denitrification performance was evaluated using a sequencing batch reactor (SBR) under intermittent aeration. Complete denitrification was observed without N₂O accumulation when the initial nitrite concentration was 100–500 mg-N·L⁻¹. When the initial nitrate concentration was 75–300 mg-N·L⁻¹, 95–96% of NO₃⁻-N was completely reduced to N₂ gas. Acetate was the most effective sole carbon source for the complete denitrification of the SBR under intermittent aeration, and 99% of NO₃⁻-N was reduced to N₂ gas. The optimum COD/N ratio was 8–12 for the complete denitrification, while NO₂⁻ accumulation was observed at low COD/N ratios of 1 and 2. In this study, N₂O accumulation was not observed during the denitrification process regardless of operational condition. Paracoccus (15–68%), a representative aerobic denitrifying bacterium, was dominant in the SBR during the denitrification process, and the intermittent aeration condition could affect the abundance of Paracoccus in this study.

Keywords:

• Heterotrophic denitrification
• intermittent aeration
• nitrogen removal
• denitrifying bacteria
• sequencing batch reactor

Additional information

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2016R1A2B4015007).