Micro-Analysis of Nitrous Oxide Accumulation in Denitrification Under Acidic Conditions : The Role of Ph and Free Nitrous Acid
N 2 O, as an energy gas, is of increasing interest for its recovery from wastewater treatment. Acidic pH is one of the important factors affecting N 2 O accumulation during denitrification, but the mechanism still needs further clarification. In this study, the production efficiency of N 2 O increased from 1.0 to 65.0% with pH decreasing from 6.5 to 4.5 from nitrate-based denitrification using batch tests, accompanied by an increase in the nitrite accumulation. To further explore the mechanism, the net volumetric reaction rates of N 2 O within denitrified sludge aggregates were quantified by application of a microelectrode. When using N 2 O as source of nitrogen, the N 2 O consumption rates decreased with decreasing pH regardless of the presence of free nitrous acid (FNA), indicating that both the FNA and the hydrogen ion concentrations inhibit nitrous oxide reductase (NOS) activity, and hydrogen ion concentration is the true inhibitor. When using NO as source of nitrogen, the net volumetric production rates of N 2 O increased with decreasing pH, and they were higher in the presence of FNA compared to those in the absence of FNA, revealing that the increase in nitrite substrate promotes N 2 O production. In summary, the inhibition of NOS by hydrogen ions and FNA and the increase of substrate from nitrite accumulation are the main reasons for N 2 O enrichment under a low-pH condition
Year of publication: |
[2022]
|
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Authors: | Lv, Yongtao ; Zhang, Xuyang ; Zhu, Chuanshou ; Lin, Li ; Sun, Ting ; Wang, Xudong ; Wang, Lei |
Publisher: |
[S.l.] : SSRN |
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