C/N对单级脱氮系统N_2O排放量及其途径的影响

Effect of C/N ratio on amount and origins of N_2O emission in one-stage nitrogen removal systems

采用4组0.5 L的批式反应器,调节进水初始NH_4^+-N为100 mg·L^(-1),控制温度为30℃,DO为(2.00±0.20)mg·L^(-1),以葡萄糖为有机碳源,采用化学抑制法研究进水C/N分别为0、0.5、1.0和1.5时,单级脱氮系统的氮转化情况、N_2O排放量及N_2O排放途径。结果表明,反应器进水C/N从0升高至1.5,在6 h时系统TN去除率由14.5%增至23.5%,而系统N_2O排放量由180μg减至10μg,N_2O转化率由2.5%降至0.1%。随着进水C/N的升高,氨氧化菌(AOB)反硝化产生的N_2O排放量在3.6~11.7μg之间波动,而同步硝化-反硝化产生的N_2O排放量降幅明显,由176.8μg降至5.3μg。当C/N为较低的0和0.5时,同步硝化-反硝化对N_2O排放贡献率均达到85%以上,系统N_2O排放途径主要为同步硝化-反硝化;当C/N为较高的1.0和1.5时,AOB反硝化对N_2O排放贡献率为45.9%和26.5%,系统N_2O排放途径主要为同步硝化-反硝化和AOB反硝化作用。

Chemical inhibitors were used to study the impact of COD / TN（ C / N） ratios on ammonium transformation,amount of N_2O emission and origins of N_2O emission in one-stage nitrogen removal systems. Four batch reactors with an effective volume of 0. 5 L per reactor were utilized. Four C / N ratios（ 0,0. 5,1. 0,and 1. 5） were achieved by adding different amounts of glucose,while the initial NH_4＋-N concentration was kept constant at 100mg·L-1. In addition,temperature was controlled at 30 ℃,and dissolved oxygen concentration was（ 2. 00 ±0. 20） mg·L^（-1）. Results showed that when the C / N ratios increased from 0 to 1. 5,TN removal efficiency increased from 14. 5% to 23. 5%,while the amount of N_2O emission and the conversion efficiency of N_2O decreased from 180 to 10 μg and 2. 5% to 0. 1%,respectively. With the increase of the C / N ratio,the amount of N_2O emission during denitrification by ammonia oxidizing bacteria（ AOB） ranged from 3. 6 to 11. 7 μg,while the amount of N_2O emission during simultaneous nitrification-denitrification decreased from 176. 8 to 5. 3 μg. Simultaneous nitrification-denitrification was the main source of N_2O emission at low C / N ratios（ 0 and 0. 5）,and contributed to over 85% of N_2O emission. However,at high C / N ratios（ 1. 0 and 1. 5）,both simultaneous nitrification-denitrification and AOB denitrification contributed to N_2O emission,with the contribution of AOB denitrification being 45. 9% and 26. 5%,respectively.