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Enhanced simultaneous nitrification and denitrification in treating low carbon-to-nitrogen ratio wastewater: Treatment performance and nitrogen removal pathway
- Chai, Hongxiang, Xiang, Yu, Chen, Rong, Shao, Zhiyu, Gu, Li, Li, Li, He, Qiang
- Bioresource technology 2019 v.280 pp. 51-58
- ammonia, ammonium, biofilm, carbon nitrogen ratio, chlorates, denitrification, denitrifying microorganisms, energy conservation, nitrate reductase, nitrates, nitrification, nitrites, nitrogen, nitrous oxide, nitrous oxide production, wastewater, wastewater treatment
- Simultaneous nitrification and denitrification (SND) is an energy-saving wastewater treatment process, however, the nitrogen removal pathways are not clear. An enhanced SND sequencing batch biofilm reactor with a SND ratio above 97.3% was built to treat low carbon to nitrogen ratio wastewater. When traditional nitrification was inhibited, ammonia removal efficiency still reached 45% in 8 h while the NO₃⁻ and NO₂⁻ concentration was less than 3 mg/L and 0.01 mg/L during the complete process, respectively. The pathways that could not be suppressed by the inhibitors (ATU and ClO₃⁻) were stimulated by heterotrophic nitrifiers and aerobic denitrifiers with periplasmic nitrate reductase and contributed 55% of the total removed NH₄⁺ and produced 51% of the emitted N₂O. The contributions of different nitrogen removal pathways indicate that the unconventional pathways are important in wastewater treatment system and inhibitors should be carefully used in nitrogen removal pathway assays.