At present, the effects on anammox granular sludge (AnGS) of long-term exposure to low-concentration polystyrene nanoplastics (PS-NPs) and the associated mechanisms are still unclear. In this paper, the effects of continuous PS-NP exposure (1–2 mg/L, 225 d) on the nitrogen removal performance, activity and granule stability of an AnGS reactor were studied. In the first 100 d, the nitrogen removal performance of the reactor was stable, and the specific anammox activity (SAA) gradually increased. After 225 d, the nitrogen removal performance of the reactor decreased, and the AnGS SAA_NH4⁺_-N and SAA_NO2^-_-N decreased by 44.5% and 57.6%, respectively, compared with those at 100 d. Long-term PS-NP exposure increased the oxidative stress level of cells and led to membrane damage. Decreases in the content of extracellular polymeric substances (EPS) and extracellular protein (PN) hydrophobicity led to a decrease in the aggregation performance of AnGS. PS-NPs adhered to EPS to form a dense structure, blocking AnGS mass transfer channels and reducing AnGS strength, and some granular sludge was cracked. Candidatus Kuenenia and Candidatus Jettenia were inhibited, and their abundance decreased. The effects of PS-NP exposure on AnGS depended on the accumulation of PS-NPs, and significant inhibitory effects were observed at 118 mg PS-NPs/g VSS. This work helps to assess the potential risk of long-term AnGS exposure to low-concentration PS-NPs and is of great significance to maintain the high nitrogen removal performance and stability of AnGS.

目前，长期暴露于低浓度聚苯乙烯纳米塑料（PS-NPs）对厌氧氨氧化颗粒污泥（AnGS）的影响及相关机制尚不清楚。在本文中，研究了连续暴露 PS-NP（1-2 mg/L，225 d）对 AnGS 反应器的脱氮性能、活性和颗粒稳定性的影响。前100 d反应器脱氮性能稳定，厌氧氨氧化比活性（SAA）逐渐升高。225 d后，反应器脱氮性能下降，AnGS SAA _NH4 ⁺ _-N和SAA _NO2 ^- _-N与 100 d 相比，分别下降 44.5% 和 57.6%。长期暴露于 PS-NP 会增加细胞的氧化应激水平并导致细胞膜损伤。细胞外聚合物（EPS）含量和细胞外蛋白（PN）疏水性的降低导致 AnGS 的聚集性能下降。PS-NPs 粘附在 EPS 上形成致密结构，阻塞 AnGS 传质通道，降低 AnGS 强度，部分颗粒污泥破裂。Candidatus Kuenenia和Candidatus Jettenia受到抑制，它们的丰度下降。PS-NP 暴露对 AnGS 的影响取决于 PS-NPs 的积累，在 118 mg PS-NPs/g VSS 时观察到显着的抑制作用。这项工作有助于评估 AnGS 长期暴露于低浓度 PS-NPs 的潜在风险，对保持 AnGS 的高脱氮性能和稳定性具有重要意义。