4-nonylphenol (4-NP) is one of the most relevant endocrine-disrupting compounds that can be found in wastewaters. In this work, the effect of dosing 1 mg·L⁻¹ of 4-NP to simulated wastewater on the activated sludge process was assessed. For it, two laboratory sequencing batch reactors (SBR) were operated for 94 days, adding 1 mg·L⁻¹ of 4-NP to the wastewater entering one of them (SBR-NP), while the other one (SBR-B) worked as a control reactor. Holistic study of 4-NP influence on activated sludge treatment was carried out, which included both the evolution of the biomass characteristics and the effect of this substance on reactor performance. Although the COD removal efficiency in SBR-NP was lower than in the reactor without 4-NP addition (SBR-B), COD removal efficiency of SBR-NP was always higher than 90%. From day 50, nitrification bacteria were inhibited in SBR-NP and cellular viability decreased from 85.7 ± 11.0% in the first 50 days to 63.0 ± 10.2% in the last 44 days. Concerning the microbial community analysis, both Nitrosomonas and Nitrospira abundances decreased in SBR-NP (from 0.62% to 0.45%, and from 2.39% to 1.01%, respectively). Proteobacteria abundance was considerably higher in SBR-NP at the end of the experiment (44.28% in SBR-NP and 25.88% in SBR-B), which was due to increase of Aquabacterium genus (13.00% and 0.00% in SBR-NP and SBR-B, respectively), playing an important role in 4-NP degradation. Thus, 4-NP presence, in the concentrations studied, affected heterotrophic and autotrophic bacteria differently, having a negative effect in the second group.

4-壬基酚 (4-NP) 是废水中最相关的内分泌干扰化合物之一。在这项工作中，评估了在模拟废水中加入 1 mg·L ^-1的 4-NP 对活性污泥工艺的影响。为此，两台实验室序批式反应器 (SBR) 运行 94 天，添加 1 mg·L ^-14-NP 对进入其中之一的废水（SBR-NP），而另一个（SBR-B）用作控制反应器。对 4-NP 对活性污泥处理的影响进行了整体研究，包括生物质特性的演变和该物质对反应器性能的影响。虽然 SBR-NP 的 COD 去除率低于未添加 4-NP 的反应器 (SBR-B)，但 SBR-NP 的 COD 去除率始终高于 90%。从第 50 天开始，SBR-NP 中的硝化细菌受到抑制，细胞活力从前 50 天的 85.7 ± 11.0% 下降到最后 44 天的 63.0 ± 10.2%。关于微生物群落分析，Nitrosomonas和NitrospiraSBR-NP 的丰度下降（分别从 0.62% 下降到 0.45%，从 2.39% 下降到 1.01%）。实验结束时 SBR-NP 中的变形菌丰度显着升高（SBR-NP 中为 44.28%，SBR-B 中为 25.88%），这是由于水生细菌属的增加（ SBR-NP 中分别为 13.00% 和 0.00% 和SBR-B，分别），在 4-NP 降解中起重要作用。因此，在所研究的浓度下，4-NP 的存在对异养和自养细菌的影响不同，对第二组有负面影响。