不同碳源驯化聚糖菌反硝化及N2O释放特性

为了确定反硝化聚糖菌(DGAOs)的脱氮性能及N₂O释放特性,采用序批式生物反应器,分别以乙酸钠和葡萄糖为碳源(反应器分别记作SBRAc和SBRGl),考察其脱氮过程中的碳源变化以及N₂O释放特性。结果表明,SBRAc和SBRGl的总氮去除率分别为(80.2±2.8)%和(63.4±3.5)%,N₂O产率分别为(7.16±1.43)%和(13.35±2.46)%。以乙酸钠为碳源时,聚糖菌厌氧阶段吸收的有机物主要以胞内聚-β-羟基烷酸(PHA)形式储存;以葡萄糖为碳源时,部分有机物用于胞内糖原(Gly)的积累,PHA合成量减少。聚糖菌内源反硝化过程中,依次利用胞内PHA和Gly作为内碳源,且PHA提供电子的速率远大于Gly,导致SBRGl内NO₂^-大量积累、N₂O释放量增加。NO₂^-对氧化亚氮还原酶活性的抑制效应是导致聚糖菌内源反硝化过程释放N₂O的主要因素。与葡萄糖相比,乙酸钠更易被反硝化聚糖菌吸收为易利用的内碳源PHA,并降低反硝化过程中N₂O的释放量。

Characteristics of Denitrification and N2O Emission of Acclimated Glycogen Accumulating Organisms under Different Carbon Sources

In order to investigate the denitrification efficiency and N₂O emission characteristic of denitrifying glycogen accumulating organisms(DGAOs),variation of the endogenous polymer and N₂O emission characteristic during endogenous denitrification process were explored in two separated sequencing batch reactors(SBRAc and SBRGl)using sodium acetate and glucose as carbon sources respectively.The total nitrogen removal efficiencies of SBRAc and SBRGl were(80.2±2.8)%and(63.4±3.5)%,and the N₂O yields were(7.16±1.43)%and(13.35±2.46)%,respectively.When sodium acetate was used as carbon source,organics absorbed by DGAOs in anaerobic stage was stored in the form of endogenous polyhydroxyalkanoate(PHA).When glucose was used as carbon source,part of the organics was used for intracellular glycogen(Gly)accumulation,and PHA synthesis decreased.In the endogenous denitrification process of DGAOs,PHA and Gly were successively used as endogenous carbon sources,and the rate of electron supply by PHA was much higher than that of Gly,leading to accumulation of a large amount of NO₂^-and increase of N₂O emission in SBRGl.The inhibitory effect of NO₂^-on activity of nitrous oxide reductase was the main factor leading to N₂O emission during the endogenous denitrification of DGAOs.Compared with glucose,sodium acetate was more easily absorbed by DGAOs as an easily used endogenous carbon source PHA,and the emission of N₂O during denitrification was reduced.