Nitrite Accumulation during the Denitrification Process in SBR for the Treatment of Pre-treated Landfill Leachate

The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.

在 denitrification 过程的亚硝酸根累积与定序对待预先对待的垃圾堆的批反应堆(SBR ) 被调查沥滤吃在缺氧 / 厌氧的起来流动厌氧的污泥床(UASB ) 。亚硝酸根在不同起始的硝酸盐集中显然积累(64.9,54.8,49.3 和 29.5 mg·； L −1) 和低温度，和氧化减小潜力(ORP ) 上的点介绍的二个裂缝显示硝酸盐和亚硝酸根减小的结束。通常，硝酸盐减小率被用作唯一的参数描绘 denitrification 率，和亚硝酸根甚至没被测量。为精确性，全部的氧化的氮(硝酸盐 + 亚硝酸根) 被用作一项措施，尽管描绘这个过程的细节可以被俯看。另外，批测试被进行在 denitrification 期间在亚硝酸根累积上调查 C/N 比率的效果和碳来源的类型。碳来源为到亚硝酸根的硝酸盐的减小是足够的，这被观察，要不是到氮气体的亚硝酸根的进一步的减小，当 C/N 基于 denitrification 的 stoichiometry 在 3.75 的理论批评水平下面时，是缺乏的。除了葡萄糖，在这个工作使用的五碳来源可以引起亚硝酸根累积。从试验性的结果和引用文学， Alcaligene 种类可以在 SBR 激活污泥的系统被包含，这被结束。