Feasibility of Adjusting the S₂O₃²⁻/NO₃⁻ Ratio to Adapt to Dynamic Influents in Coupled Anammox and Denitrification Systems

• Main Authors: Yuqian Hou, Shaoju Cheng, Mengliang Wang, Chenyong Zhang, Bo Liu
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: anammox; coupled denitrification; s/n ratio regulation strategy; total nitrogen removal; competition and cooperation
• Online Access: https://www.mdpi.com/1660-4601/17/7/2200

In this study, anammox, sulfur-based autotrophic denitrification, and heterotrophic denitrification (A/SAD/HD) were coupled in an expanded granular sludge bed (EGSB) reactor to explore the feasibility of enhancing denitrification performance by adjusting the S₂O₃^2&#8722;/NO₃^&#8722; (S/N) ratio to accommodate dynamic influents. The results indicated that the optimal influent conditions occurred when the conversion efficiency of ammonium (CEA) was 55%, the S/N ratio was 1.24, and the chemical oxygen demand (COD) was 50 mg/L, which resulted in a total nitrogen removal efficiency (NRE) of 95.0% &#177; 0.5%. The S/N ratio regulation strategy was feasible when the influent COD concentration was less than 100 mg/L and the CEA was between 57% and 63%. Characterization by 16S rRNA sequencing showed that <i>Candidatus Jettenia</i> might have contributed the most to anammox, while <i>Thiobacillus</i> and <i>Denitratisoma</i> were the dominant taxa related to denitrification. The findings of this study provide insights into the effects of CEA and COD on the performance of the A/SAD/HD system and the feasibility of the S/N ratio regulation strategy.