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Updated: Jun 14, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Advanced nitrogen removal system coupling partial nitritation, anammox, denitrification and oxygen-permeable
Xifang Tang1, Bao-Shan Xing2, Yong-Ning Feng1
1School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, China.
Abstract:
The application of one-stage partial nitritation (PN)/anammox systems is constrained by precise dissolved oxygen (DO) regulation and suppression of nitrite-oxidizing bacteria (NOB). In this study, an expanded granular sludge bed (EGSB) reactor integrated with oxygen-permeable hollow-fibre membranes was developed, in which the membranes served solely as a controllable oxygen supply. Over 200 days of operation, dead-end aeration enabled stable PN/anammox coupling, achieving a high total nitrogen removal efficiency of 93.5 ± 3.9%, compared with 33.7 ± 22.4% under cross-flow aeration. Dead-end aeration maintained ultra-low DO (0.02-0.10 mg/L), effectively inhibiting NOB while avoiding excessive FA accumulation. Enhanced sludge granulation and a high proportion of tightly bound EPS (89%) supported microbial stratification, with ammonia-oxidizing bacteria (AOB) enriched in the outer layer and anammox bacteria in the core. Functional gene analysis confirmed coordinated enhancement of nitrification, anammox, and denitrification pathways. This study provides a new process configuration for robust one-stage PN/anammox by decoupling oxygen delivery from biomass retention.
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