Optimization of the intermittent aeration to improve the stability and flexibility of a mainstream hybrid partial nitrification-anammox system

• Published in: Chemosphere (Oxford) Vol. 261; p. 127670
• Main Authors: Xu, Zaizhou, Zhang, Liang, Gao, Xinjie, Peng, Yongzhen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2020
• Subjects: Hybrid system; Intermittent aeration; Mainstream anammox; NOB suppress; Partial nitrification; Partial nitrification; Intermittent aeration; NOB suppress; Mainstream anammox; Hybrid system
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127670

Intermittent aeration is favorable for maintaining a long-term sewage partial nitrification-anammox (PN/A) process but the underlying mechanism is not yet fully understood. In this study, mainstream PN/A was established in an integrated fixed film activated sludge (IFAS) PN/A reactor and nitrite oxidization bacteria (NOB) activity was continuously suppressed. The suppression of NOB was significantly affected by the dissolved oxygen (DO) concentration during the aeration period as well as the duration of anoxic period. NOB was more suppressed in the hybrid system under a low DO level (0.5 mg/L) than under a high DO level (1.5–1.8 mg/L). Meanwhile, shortening the anoxic time from 40 to 20 min and keeping low DO during the intermittent aeration cycle could still suppress NOB activity, increasing the nitrogen removal rate by 40%. Biomass segregation was also enhanced by low DO, which favors the NOB inhibition in IFAS PN/A system. Overall, under an optimized intermittent aeration, a stable and high nitrogen removal efficiency (80–89%) with a nitrogen removal rate of 0.101 kg-N/(m3·d). This study is useful to supports the application of PN/A in sewage treatment. [Display omitted] •High TIN removal efficiency of 85 ± 4% was achieved mainstream PN/A system.•DO was more important than anoxic time for NOB inhibition by intermittent aeration.•Nitrogen removal rate was increased 40% by optimizing intermittent aeration model.•Biomass segregation contributed to the stability of hybrid PN/A system.