To explore the potential impacts of nanoscale zero-valent iron (nZVI) particles on nitrite accumulation performance of nitritation granular sludge (NGS), two types of NGS (NGS_A and NGS_H) with different spatial morphologies were employed to exposure under a wide dosage of nZVI in batch tests. The biosorption behavior of nZVI was also investigated by determining adsorption isotherm. Results showed that the ecotoxic effect of nZVI was ascribed to its fast adsorption to the granules. Although NGS_A and NGS_H shared a similar bacterial community structure dominated by genus Nitrosomonas based on high-throughput pyrosequencing, the compact and small granules of NGS_A showed a stronger tolerance for nZVI exposure than NGS_H with loose spatial structure. The 50% inhibition dosage of nZVI for ammonium-oxidizing bacteria activity in NGS_A and NGS_H was 88.5 and 21.3 mg g⁻¹ VSS, respectively. As a crucial self-protection mechanism of microbes, the secretion of extracellular polymeric substances was dramatically enhanced with nZVI exposure at a low dosage, and a simultaneous decrease in both extracellular polymeric substances contents and ammonium-oxidizing activity of NGS was observed with a high accumulation of total iron in sludge phase. Overall, the results suggested that ammonium-oxidizing bacteria in granules were susceptible to inhibition by nZVI exposure, and release of engineered nanoparticles into wastewater treatment system increased the risk of failure in autotrophic nitrogen removal process.

中文翻译：

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纳米零价铁对不同空间形态硝化颗粒污泥亚硝酸盐累积性能的影响及其生物吸附行为

为了探索纳米级零价铁（nZVI）颗粒对硝化颗粒污泥（NGS）亚硝酸盐积累性能的潜在影响，采用两种具有不同空间形态的NGS（NGS _A和NGS _H）进行大剂量暴露批处理测试中nZVI的数量。还通过确定吸附等温线研究了nZVI的生物吸附行为。结果表明，nZVI的生态毒性作用归因于其对颗粒的快速吸附。尽管NGS _A和NGS _H在高通量焦磷酸测序的基础上共享了以亚硝化单胞菌为主体的相似细菌群落结构，但NGS _A的紧凑小颗粒与具有松散空间结构的NGS _H相比，NZVI的耐受性更强。nZVI对NGS _A和NGS _H中的铵氧化细菌活性的50％抑制剂量为88.5和21.3 mg g ^-1 VSS。作为微生物的重要自我保护机制，低剂量的nZVI暴露可显着增强细胞外聚合物的分泌，同时高积累量可观察到细胞外聚合物含量和NGS的铵氧化活性同时降低污泥阶段的总铁含量。总体而言，结果表明颗粒中的铵氧化细菌易于受到nZVI暴露的抑制，工程化的纳米颗粒释放到废水处理系统中会增加自养氮去除过程失败的风险。