Shi Shuohui, He Xuejie, He Lei, Fan Xing, Shu Bin, Zhou Jian, He Qiang
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
Water Res. 2023 Feb 15;230:119493. doi: 10.1016/j.watres.2022.119493. Epub 2022 Dec 15.
The anaerobic/aerobic/anoxic (A/O/A) process is a promising biotechnology to intensify denitrification in low carbon/nitrogen (C/N) wastewater treatment, but the neglected typical rate-limiting step-nitrification-would hinder its wider application. Heterotrophic nitrification driven by intracellular carbon (PHAs) could enhance nitrification and achieve endogenous simultaneous nitrification and denitrification (ESND) in the A/O/A process, but its feasibility remains unexamined. Here we established four A/O/A-SBRs at different C/N ratios (3, 7.5, 12, and 16.5) to address the above-mentioned knowledge gaps. The results showed that organic supplementation promoted both nitrification and denitrification (performance and relevant enzymatic activities) until organic overdose (C/N = 16.5) exacerbated niche competitions from other non-functional heterotrophs. qPCR and batch tests indicated that high C/N ratios inhibited autotrophic nitrifiers, and heterotrophic nitrifiers (HNB) dominated in the enhanced nitrification. Given the high HNB contribution (43.7%) and low COD variation (< 10 mg L) in the SND (76.4%) of CN12, we proposed a potential SND pathway based on heterotrophic nitrification and denitrification driven by PHAs and verified it with batch tests. Microbial and functional analyses suggested that CN12 favored the intracellular carbon transformation and harbored the minimum autotrophic nitrifiers, supporting the dominance of ESND in the enhanced SND. Our findings expand the understanding of the relationships between intracellular carbon transformation and SND and provide a novel nitrogen removal pathway for the practical application of the A/O/A process.
厌氧/好氧/缺氧（A/O/A）工艺是一种很有前景的生物技术，可强化低碳/氮（C/N）废水处理中的反硝化作用，但被忽视的典型限速步骤——硝化作用——会阻碍其更广泛的应用。由细胞内碳（聚羟基脂肪酸酯，PHA）驱动的异养硝化作用可增强硝化作用，并在A/O/A工艺中实现内源性同步硝化反硝化（ESND），但其可行性仍未得到检验。在此，我们建立了四个不同C/N比（3、7.5、12和16.5）的A/O/A-SBR，以填补上述知识空白。结果表明，有机添加物促进了硝化和反硝化作用（性能及相关酶活性），直到有机过量（C/N = 16.5）加剧了来自其他非功能性异养菌的生态位竞争。定量聚合酶链反应（qPCR）和批次试验表明，高C/N比抑制了自养硝化菌，而异养硝化菌（HNB）在增强的硝化作用中占主导地位。鉴于在CN12的同步硝化反硝化（SND，76.4%）中HNB贡献高（43.7%）且化学需氧量（COD）变化低（< 10 mg/L），我们提出了一种基于PHA驱动的异养硝化和反硝化作用的潜在SND途径，并通过批次试验进行了验证。微生物和功能分析表明，CN12有利于细胞内碳转化，且自养硝化菌最少，支持了ESND在增强的SND中的主导地位。我们的研究结果扩展了对细胞内碳转化与SND之间关系的理解，并为A/O/A工艺的实际应用提供了一条新的脱氮途径。
