Effect of the proportion of nitrite on denitrification and N2O release
FU Kunming,, JIN Yiran, LIU Fanqi, QIU Fuguo, CAO Xiuqin Key Laboratory of Urban Storm Water System and Water Environment, Ministry of Education, School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
Abstract:Aiming at the problem of large amount of N2O release during sewage treatment, the effects of different ${\rm{NO}}_2^ - $-N ratios on the denitrification process and N2O release were studied. At the total nitrogen concentration of 100 mg·L?1, the change of ${\rm{NO}}_2^ - $-N proportion was performed to conduct batch experiment. The reactor denitrification rate and nitrogen index variations were studied. The results show that the denitrification efficiency increased with the increase of the initial ${\rm{NO}}_2^ - $-N ratio, in which the ${\rm{NO}}_2^ - $-N concentration basically increased first and then decreased. The higher the initial ${\rm{NO}}_2^ - $-N ratio, the faster the degradation rate of ${\rm{NO}}_3^ - $-N and the more ${\rm{NO}}_2^ - $-N accumulation. With the increase of the initial ${\rm{NO}}_2^ - $-N ratio, the accumulation rate, maximum accumulation value and conversion rate of N2O both gradually increased. The highest values were 18.828 mg·(g·h)?1, 22.123 mg·L?1 and 24.05%, respectively. As the initial ${\rm{NO}}_2^ - $-N ratio increased, the concentration of free nitrous acid (FNA) increased, resulting in more N2O accumulation. FNA concentration may be the cause of the large N2O accumulation. Key words:nitrite/ denitrification/ free nitrous acid(FNA)/ N2O.
图1不同初始${\bf{NO}}_2^ -$-N占比下反应器内氮素的变化 Figure1.Variations of nitrogen in the bioreactors at different initial ${\rm{NO}}_2^ - $-N concentrations
图2不同初始${\bf{NO}}_2^ - $-N占比下反应器内${\bf{NO}}_3^ - $-N的变化 Figure2.Variations of ${\rm{NO}}_3^ - $-N in the bioreactors at different initial ${\rm{NO}}_2^ - $-N concentrations
图3不同初始${\bf{NO}}_2^ - $-N占比下反应器内${\bf{NO}}_2^ - $-N的变化 Figure3.Variations of ${\rm{NO}}_2^ - $-N in the bioreactors at different initial ${\rm{NO}}_2^ - $-N concentrations
图5不同初始${\bf{NO}}_2^ - $-N占比下各反硝化酶的电子消耗速率和电子分布率 Figure5.Electron consumption rate and distribution rate of denitrification enzymes at different initial ${\rm{NO}}_2^ - $-N concentrations
表1不同初始${\rm{NO}}_2^ - $-N浓度时实验的运行条件 Table1.Operational conditions at different initial ${\rm{NO}}_2^ - $-N concentrations mg·L?1
${\rm{NO}}_x^ - $-N
${\rm{NO}}_2^ - $-N
${\rm{NO}}_3^ - $-N
FNA
100
0
100
0
100
5
95
0.003 9
100
10
90
0.007 7
100
20
80
0.015 4
100
40
60
0.030 8
100
100
0
0.076 9
${\rm{NO}}_x^ - $-N
${\rm{NO}}_2^ - $-N
${\rm{NO}}_3^ - $-N
FNA
100
0
100
0
100
5
95
0.003 9
100
10
90
0.007 7
100
20
80
0.015 4
100
40
60
0.030 8
100
100
0
0.076 9
下载: 导出CSV 表2不同初始${\bf{NO}}_2^ - $-N占比下反应器内N2O动力分析 Table2.Kinetic analysis of bioreactors at different initial ${\rm{NO}}_2^ -\text{-}{\rm{N}}$ concentrations
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Key Laboratory of Urban Storm Water System and Water Environment, Ministry of Education, School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China Received Date: 2020-06-09 Accepted Date: 2020-09-16 Available Online: 2021-03-24 Keywords:nitrite/ denitrification/ free nitrous acid(FNA)/ N2O Abstract:Aiming at the problem of large amount of N2O release during sewage treatment, the effects of different ${\rm{NO}}_2^ - $-N ratios on the denitrification process and N2O release were studied. At the total nitrogen concentration of 100 mg·L?1, the change of ${\rm{NO}}_2^ - $-N proportion was performed to conduct batch experiment. The reactor denitrification rate and nitrogen index variations were studied. The results show that the denitrification efficiency increased with the increase of the initial ${\rm{NO}}_2^ - $-N ratio, in which the ${\rm{NO}}_2^ - $-N concentration basically increased first and then decreased. The higher the initial ${\rm{NO}}_2^ - $-N ratio, the faster the degradation rate of ${\rm{NO}}_3^ - $-N and the more ${\rm{NO}}_2^ - $-N accumulation. With the increase of the initial ${\rm{NO}}_2^ - $-N ratio, the accumulation rate, maximum accumulation value and conversion rate of N2O both gradually increased. The highest values were 18.828 mg·(g·h)?1, 22.123 mg·L?1 and 24.05%, respectively. As the initial ${\rm{NO}}_2^ - $-N ratio increased, the concentration of free nitrous acid (FNA) increased, resulting in more N2O accumulation. FNA concentration may be the cause of the large N2O accumulation.
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