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Updated: Feb 14, 2026

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Model-Based Evaluation of N2O Production Pathways in the Anammox-Enriched Granular Sludge Cultivated in a Sequencing
Xi Lu1,2, Tiago D S Pereira3, Hussein E Al-Hazmi2
1Institute of Environmental Science and Engineering , Tongji University , 1239 Siping Road , Shanghai , 200092 , China.
Abstract:
A mechanistic model was developed as an extension of the Activated Sludge Model No. 1 to describe three nitrous oxide (N2O) production pathways in a laboratory-scale anammox-enriched granular sequencing batch reactor. Heterotrophic denitrification and two processes mediated by ammonia oxidizing bacteria (AOB), that is, ammonia (NH4+) oxidation via hydroxylamine (NH2OH) and autotrophic denitrification, were considered. A systematic model calibration and validation protocol was developed to obtain a unique set of kinetic parameters in the extended model. The dynamic nitrate (NO3-), nitrite (NO2-), NH4+ and N2O behaviors were accurately predicted (R2 ≥ 0.81) under five different nitrogen loading conditions. The predicted N2O production factor ranged from 1.7 to 2.9%. The model-based analysis also revealed the dominant N2O production mechanisms in terms of the actual process conditions, that is, NH4+ oxidation via NH2OH when only NH4+ was supplied, heterotrophic denitrification when only NO2- was supplied, and a shift of the dominant mechanism when a mixture of NH4+ and NO2- was supplied.
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