A/O-SBR中羟胺氧化酶活性变化与N_2O的产生

Nitrous Oxide Emission and Hydroxylamine Oxidase Activity in Anoxic /Aerobic Sequencing Batch Reactor

在以A/O方式运行的SBR中,研究了三种不同曝气量下硝化与反硝化过程中N2O的释放及污泥羟胺氧化酶(HAO)活性的变化。结果表明,在曝气量为0.6 L/min下,N2O总释放量为2.747 mg;好氧段的HAO活性同N2O释放浓度的变化趋势相反。在曝气量为0.8、1.0 L/min下,N2O的总释放量分别为1.032、1.006 mg,相差不大。在曝气量为0.8 L/min下,好氧阶段的HAO活性与N2O释放浓度的变化呈正相关,N2O的释放浓度随HAO活性的增减而相应变化。在曝气量为1.0 L/min下,好氧段的HAO活性同N2O释放浓度变化呈相反趋势,HAO活性出现极大值时,N2O释放量出现极小值;反之,亦然。在三种不同曝气方式下,曝气量为0.6 L/min时,缺氧段N2O的释放与HAO作用有关,其他条件下N2O的释放则与HAO无关。因此,硝化阶段N2O的释放与HAO活性密切相关,HAO是影响N2O释放途径的关键酶;反硝化阶段释放的N2O主要是反硝化作用的结果,仅当硝化反应进行得不彻底时,反硝化释放的N2O才与HAO相关。

Laboratory scale anoxic/aerobic sequencing batch reactor （A/O SBR） was used to investigate the emission of nitrous oxide （ N2 O） and activity of hydroxylamine oxidase （HAO） during nitrification and denitrifieation at three aeration rates. When the aeration rate was 0.6 L/min, N2O emission amount was 2. 747 rag, and hydroxylamine oxidase activity was negatively correlated to N2O emission in the aerobic zone. When the aeration rate was 0.8 L/min, N2O emission amount decreased to 1. 032 rag, and hydroxylamine oxidase activity was positively correlated to N2O emission in the aerobic zone. When the aeration rate was 1.0 L/min, N2O emission amount was 1. 006 rag, and hydroxylamine oxidase activity was negatively correlated to N2O emission in the aerobic zone. In the anoxie zone, N2O emission was correlated to hydroxylamine oxidase activity only at the aeration rate of 0.6 L/min. N2O emission was closely correlated to hydroxylamine oxidase activity during nitrification, and HAO was the key enzyme restricting N2O emission. N2O emitted during denitrification was the result of denitrification, and N2O emission was correlated to hydroxylamine oxidase activity only during incomplete nitrification.