State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, Ghent 9000, Belgium.
Sci Rep. 2016 Jun 29;6:28880. doi: 10.1038/srep28880.
For the application of biofilm processes, a better understanding of nitrous oxide (N2O) formation within the biofilm is essential for design and operation of biofilm reactors with minimized N2O emissions. In this work, a previously established N2O model incorporating both ammonia oxidizing bacteria (AOB) denitrification and hydroxylamine (NH2OH) oxidation pathways is applied in two structurally different biofilm systems to assess the effects of co- and counter-diffusion on N2O production. It is demonstrated that the diffusion of NH2OH and oxygen within both types of biofilms would form an anoxic layer with the presence of NH2OH and nitrite ( ), which would result in a high N2O production via AOB denitrification pathway. As a result, AOB denitrification pathway is dominant over NH2OH oxidation pathway within the co- and counter-diffusion biofilms. In comparison, the co-diffusion biofilm may generate substantially higher N2O than the counter-diffusion biofilm due to the higher accumulation of NH2OH in co-diffusion biofilm, especially under the condition of high-strength ammonium influent (500 mg N/L), thick biofilm depth (300 μm) and moderate oxygen loading (1-4 m(3)/d). The effect of co- and counter-diffusion on N2O production from the AOB biofilm is minimal when treating low-strength nitrogenous wastewater.
对于生物膜工艺的应用，更好地了解生物膜内一氧化二氮（N2O）的形成对于设计和运行具有最小 N2O 排放的生物膜反应器至关重要。在这项工作中，应用了先前建立的包含氨氧化细菌（AOB）反硝化和羟胺（NH2OH）氧化途径的 N2O 模型，在两种结构不同的生物膜系统中进行评估，以评估共扩散和反扩散对 N2O 生成的影响。结果表明，两种生物膜中 NH2OH 和氧气的扩散都会在存在 NH2OH 和亚硝酸盐（ ）的情况下形成缺氧层，这将导致通过 AOB 反硝化途径产生大量 N2O。因此，在共扩散和反扩散生物膜中，AOB 反硝化途径占主导地位，而不是 NH2OH 氧化途径。相比之下，由于共扩散生物膜中 NH2OH 的积累更高，尤其是在高强度氨氮进水（500 mg N/L）、厚生物膜深度（300 μm）和适度的氧气负荷（1-4 m3/d）条件下，共扩散生物膜可能会产生比反扩散生物膜更高的 N2O。当处理低强度含氮废水时，共扩散和反扩散对 AOB 生物膜中 N2O 生成的影响最小。
