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Updated: Sep 13, 2025

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors
Published on: December 6, 2018
Differentiating biosynthesis from heterotrophic nitrification/aerobic denitrification for total-nitrogen removal
Fei Liu1, Danyang Zhu1, Yaxin Chen1
1Department of Environmental Engineering, School of Environmental and Geographical Science, Shanghai Normal University, Shanghai, 200234, PR China.
Abstract:
Although classical nitrification/denitrification is the common process for total-nitrogen removal in wastewater treatment, novel nitrogen-removal processes are being evaluated. Among them, nitrogen (N) removal in one aerobic stage has been promoted as heterotrophic nitrification and aerobic denitrification (HNAD). An alternate strategy for total-N removal in one aerobic stage is nitrogen assimilation for biomass synthesis. In this work, we isolated a fungus, Apiotrichum loubieri, that cannot perform nitrification or denitrification, and we employed it for ammonium-N and total-N removal in an aerobic condition. Total-N removal by biosynthesis alone was achieved as long as the influent COD:N ratio was large enough: 24 g COD/gN for A. loubieri, which has a molecular formula of C5H7.9O2N. Adding A. loubieri to biomass that was deficient in heterotrophic activity and could not achieve total-N removal led to complete N removal by biosynthesis with a COD:N ratio of ∼28 g COD/g N. The results provide a good strategy how using mass balances on N and COD make it possible to differentiate N removal by biosynthesis versus HNAD.
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