A one-dimensional biofilm model was applied to illustrate the nitrogen conversion and removal within the heterogeneous biofilm attached on the gas-permeable membrane with different oxygen transfer coefficients: 7.5 m/d, 1.5 m/d and 0.3 m/d. Integrating the ammonia-oxidizing bacteria-mediating hydroxylamine oxidization pathway during the autotrophic nitrification and the four-step denitrification pathway during the heterotrophic denitrification, the effects of the intra-membrane aeration pressure and the influent COD/N ratio were further quantitatively evaluated on the systematic performance of nitrogen conversion. Dynamic profiles of key nitrogenous intermediates were investigated to further analyze the treatment efficacy of the targeted biofilm system. It is inapplicable for membrane with oxygen transfer coefficient of 0.3 m/d to sustain the biofilm due to the inferior treatment performance under higher influent organics and distinct nitrous oxide (N 2 O) production with elevated aeration pressures under lower influent organics. For the oxygen transfer coefficients of 7.5 m/d and 1.5 m/d, N 2 O production was detectable for the insufficient carbon source, indicating the significance of hydroxylamine oxidization. Short-cut nitrogen removal pathway could be feasible within the latter biofilm due to the nitrite accumulation, further reduced by supplementing the carbon source. Heterotrophic denitrification would contribute to the N 2 O production. Maintaining the biofilm thickness was conducive to short-cut nitrogen removal by regulating the substrate transfer and the biomass distribution along the biofilm. Besides the total nitrogen removal efficiency, the nitrite accumulation and N 2 O production were both decreased with the thickening biofilm. Inside the thinner biofilm, a short-cut pathway via nitrite might be the major pathway for nitrogen removal with distinguished N 2 O production, which could be mitigated through supplementing the carbon source.

中文翻译：

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异养膜曝气生物膜的脱氮和含氮中间体生产：数学建模研究

应用一维生物膜模型来说明附着在气体渗透膜上的异质生物膜内的氮转化和去除，具有不同的氧传递系数：7.5 m/d、1.5 m/d 和 0.3 m/d。将自养硝化过程中氨氧化菌介导的羟胺氧化途径与异养反硝化过程中的四步反硝化途径相结合，进一步定量评价了膜内曝气压力和进水COD/N比的影响。氮转化性能。研究了关键含氮中间体的动态特征，以进一步分析目标生物膜系统的处理效果。不适用于氧传递系数为0的膜。3 m/d 以维持生物膜，因为在较高的流入有机物下处理性能较差，并且在较低的流入有机物下曝气压力升高时产生明显的一氧化二氮 (N 2 O)。对于 7.5 m/d 和 1.5 m/d 的氧传递系数，可检测到碳源不足时产生 N 2 O，表明羟胺氧化的重要性。由于亚硝酸盐的积累，在后一种生物膜中的短程脱氮途径可能是可行的，通过补充碳源进一步减少。异养反硝化作用将有助于N 2 O 的产生。通过调节底物转移和生物膜沿生物膜的分布，保持生物膜厚度有利于快速脱氮。除了总脱氮效率，随着生物膜的增厚，亚硝酸盐的积累和N 2 O的产生均减少。在较薄的生物膜内，通过亚硝酸盐的捷径可能是去除氮的主要途径，具有显着的 N 2 O 生成，这可以通过补充碳源来缓解。