Anaerobic ammonia oxidation (anammox) is a cost-effective technology but its performance can be seriously inhibited by high load stress. This study has created an innovative iron-rich encrustation layer (IEL) on the surface of anammox granules (AnGS) through the addition of a certain amount of nano zero-valent iron. The IEL was formed through the aggregation of a gel network and the binding of iron species with extracellular polymeric substances (EPS), resulting in a significant increase in settling ability, EPS secretion, and heme content. Metagenomic analysis indicated a notable rise in the functional genes associated with nitrogen andiron metabolism in IEL AnGS. Under high load stress, the ammonia removal performance of AnGS without IEL severely declined. In contrast, IEL AnGS exhibited excellent ammonia removal efficiency of over 90%. The IEL served as a protective barrier for AnGS, effectively mitigating the strong shear forces, thereby enhancing their resistance to high load stress.

中文翻译：

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在厌氧氨氧化颗粒上形成富铁结壳层以抵抗高负荷应力：性能、优点和机制


厌氧氨氧化 (anammox) 是一种经济高效的技术，但其性能会受到高负荷应力的严重抑制。该研究通过添加一定量的纳米零价铁，在厌氧氨氧化颗粒（AnGS）表面创建了创新的富铁结壳层（IEL）。 IEL 是通过凝胶网络的聚集以及铁物质与细胞外聚合物 (EPS) 的结合而形成的，导致沉降能力、EPS 分泌和血红素含量显着增加。宏基因组分析表明，IEL AnGS 中与氮和铁代谢相关的功能基因显着增加。在高负荷应力下，没有 IEL 的 AnGS 的氨去除性能严重下降。相比之下，IEL AnGS 表现出优异的氨去除效率，超过 90%。 IEL 充当 AnGS 的保护屏障，有效减轻强剪切力，从而增强其对高负载应力的抵抗力。