Shortcut nitrogen removal holds significant economic appeal for mainstream wastewater treatment. Nevertheless, it is too difficult to achieve the stable suppression of nitrite-oxidizing bacteria (NOB), and simultaneously maintain the activity of ammonia-oxidizing bacteria (AOB). This study proposes to overcome this challenge by employing the novel acid-tolerant AOB, namely “ Nitrosoglobus”, in a membrane-aerated biofilm reactor (MABR) Superior partial nitritation was demonstrated in low-strength wastewater from two aspects. First, the long-term operation (256 days) under the acidic pH range of 5.0 to 5.2 showed the successful NOB washout by the free nitrous acid (FNA) of approximately 1 mg N/L. This was evidenced by the stable nitrite accumulation ratio (NAR) close to 100 % and the disappearance of NOB shown by 16S rRNA gene amplicon sequencing and fluorescence hybridization. Second, oxygen was sufficiently supplied in the MABR, leading to an unprecedentedly high ammonia oxidation rate (AOR) at 2.4 ± 0.1 kg N/(m d) at a short hydraulic retention time (HRT) of a mere 30 min. Due to the counter diffusion of substrates, the present acidic MABR displayed a significantly higher apparent oxygen affinity (0.36 ± 0.03 mg O/L), a marginally lower apparent ammonia affinity (14.9 ± 1.9 mg N/L), and a heightened sensitivity to FNA and pH variations, compared with counterparts determined by flocculant acid-tolerant AOB. Beyond supporting the potential application of shortcut nitrogen removal in mainstream wastewater, this study also offers the attractive prospect of intensifying wastewater treatment by markedly reducing the HRT of the aerobic unit.

中文翻译：

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在酸性膜曝气生物膜反应器中实现卓越的主流部分亚硝化


捷径脱氮对于主流废水处理具有巨大的经济吸引力。然而，要实现对亚硝酸盐氧化菌（NOB）的稳定抑制，同时保持氨氧化菌（AOB）的活性，难度较大。本研究提出通过在膜曝气生物膜反应器（MABR）中采用新型耐酸AOB（即“Nitrosoglobus”）来克服这一挑战，从两个方面证明了在低浓度废水中具有优异的部分亚硝化作用。首先，在 5.0 至 5.2 的酸性 pH 范围下的长期运行（256 天）表明，约 1 mg N/L 的游离亚硝酸 (FNA) 成功冲洗了 NOB。稳定的亚硝酸盐累积率（NAR）接近100%以及16S rRNA基因扩增子测序和荧光杂交显示NOB消失证明了这一点。其次，MABR 中氧气供应充足，导致氨氧化速率 (AOR) 达到 2.4 ± 0.1 kg N/(m·d)，水力停留时间 (HRT) 仅为 30 分钟，达到前所未有的高水平。由于底物的反扩散，本发明的酸性 MABR 显示出显着更高的表观氧亲和力 (0.36 ± 0.03 mg O/L)、略低的表观氨亲和力 (14.9 ± 1.9 mg N/L) 以及对FNA 和 pH 变化，与通过絮凝剂耐酸 AOB 测定的对应值进行比较。除了支持捷径脱氮在主流废水中的潜在应用之外，这项研究还提供了通过显着降低好氧单元的水力停留时间强化废水处理的诱人前景。