Evaluation of nitrogen removal and N2O emission in a novel anammox coupled with sulfite-driven autotrophic denitrification system: Influence of pH

• Published in: Journal of cleaner production Vol. 321; p. 128984
• Main Authors: Cao, Xiwei, Zhou, Xin, Xue, Mi, Chen, Jiabo, Li, Shuhan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25.10.2021
• Subjects: Anammox; Microbial community; N2O emission; Nitrogen removal; Sulfite-driven autotrophic denitrification; Sulfite-driven autotrophic denitrification; Nitrogen removal; pH; Anammox; N2O emission; Microbial community
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2021.128984

A combination of anaerobic ammonium oxidation (anammox) with sulfur-autotrophic denitrification is a promising alternative for complete nitrogen removal. Herein, a novel anammox coupled with sulfite-driven autotrophic denitrification (ASDAD) is firstly proposed. The influence of pH (8.5–6.5) on nitrogen removal and N2O emission is investigated in an anaerobic sequencing batch biofilm reactor fed with low-nitrogen wastewater containing sulfite. Long-term operation demonstrates that a maximum nitrogen removal of 94.5% occurred at a pH of 7.5 and that the contribution of autotrophic denitrification to nitrogen removal increased as the pH declined. Cyclic and batch experiments verify that anammox and sulfite-autotrophic denitrification simultaneously participates in nitrogen removal, and the stoichiometry for sulfite-driven autotrophic denitrification is firstly proposed. Furthermore, N2O accumulation is also highly correlated with the pH. The N2O emission peaks at a pH of 6.5 due to the inactivated anammox and incomplete autotrophic denitrification of nitrite at such a low pH. High-throughput sequencing reveals the coexistence of anammox (Candidatus Brocadia and Candidatus Kuenenia) and sulfur-oxidizing species (Thiobacillus). Finally, the schema for nitrogen conversion and N2O formation of ASDAD is elucidated based on metagenomic metabolism. This study offers a cost-effective and environment-friendly completely autotrophic nitrogen removal process for municipal wastewater with a low carbon-to-nitrogen ratio in practice. [Display omitted] •A novel anammox-sulfite autotrophic denitrification (ASDAD) process was developed.•Optimal pH for maximum nitrogen removal of ASDAD was 7.5•N2O emission factor was the highest as 0.71% at a pH of 6.5•Co-existence of C. Brocadia, C. Kuenenia and Thiobacillus promoted ASDAD.•Schema for nitrogen conversion and N2O formation was elucidated.