Institute of Environmental Research at Greater Bay/ Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, 510006, China.
State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
Environ Pollut. 2023 Sep 1;332:121922. doi: 10.1016/j.envpol.2023.121922. Epub 2023 May 29.
Membrane bioreactors (MBRs) have been widely applied for the treatment of wastewater that contains high concentrations of both ammonium and antibiotics. Nonetheless, information about tetracycline (TC) removal in nitrification MBRs with high ammonium loading rates (ALRs) is still very limited. Herein, the fate of TC at four different concentrations of 1, 5, 20, and 50 mg/L in three parallel lab-scale nitrification MBRs with different ALRs (named AN50, AN500, and AN1000) were investigated in this study. Excellent nitrification performance and high TC removal efficiency (90.46%) were achieved in AN1000 at influent TC concentration of 50 mg/L. Higher ALRs promoted the removal of TC at lower influent TC concentration (≤5 mg/L), while no significant difference was observed in TC removal efficiencies among different ALRs MBRs at higher influent TC concentration (≥20 mg/L), implying that the heterotrophic degradation could be strengthened after long-term exposure to high concentration of TC. Batch tests demonstrated that adsorption and biodegradation were the primary TC removal routes by nitrification sludge, of which both autotrophic ammonia oxidizers and heterotrophic microorganisms played an important role in the biodegradation of TC. FT-IR spectroscopy confirmed that amide groups on the sludge biomass contributed to the adsorption of TC. Mass balance analyses indicated that biodegradation (63.4-88.6% for AN50, 74.5-88.4% for AN500 and 74.4-91.4% for AN1000) was the major mechanism responsible for the removal of TC in nitrification MBRs, and its contribution increased with influent TC concentration, while only 1.1%-15.0% of TC removal was due to biosorption. TC was progressively degraded to small molecules and the presence of TC had no notable effect on membrane permeability. These jointly confirmed TC could be effectively removed via initial adsorption and subsequent biodegradation, while biodegradation was the primary mechanism in this study.
膜生物反应器（MBRs）已广泛应用于处理含有高浓度氨和抗生素的废水。然而，关于高氨负荷率（ALR）硝化 MBR 中四环素（TC）去除的信息仍然非常有限。在此，研究了在三个不同 ALR（分别命名为 AN50、AN500 和 AN1000）的平行实验室规模硝化 MBR 中，TC 浓度分别为 1、5、20 和 50mg/L 时，TC 的归宿。在进水 TC 浓度为 50mg/L 的情况下，AN1000 中实现了优异的硝化性能和高 TC 去除效率（90.46%）。较高的 ALR 促进了较低进水 TC 浓度（≤5mg/L）下 TC 的去除，而在较高进水 TC 浓度（≥20mg/L）下，不同 ALR MBR 中 TC 去除效率没有显著差异，这表明长期暴露于高浓度 TC 后，异养降解能力可能增强。批处理实验表明，吸附和生物降解是硝化污泥去除 TC 的主要途径，其中自养氨氧化菌和异养微生物都对 TC 的生物降解发挥了重要作用。傅里叶变换红外光谱（FT-IR）分析证实了污泥生物量上的酰胺基团对 TC 的吸附作用。质量平衡分析表明，生物降解（AN50 为 63.4%-88.6%，AN500 为 74.5%-88.4%，AN1000 为 74.4%-91.4%）是硝化 MBR 中去除 TC 的主要机制，其贡献随着进水 TC 浓度的增加而增加，而只有 1.1%-15.0%的 TC 去除是由于生物吸附。TC 逐渐降解为小分子，而 TC 的存在对膜渗透性没有显著影响。这些结果共同证实，TC 可以通过初始吸附和随后的生物降解有效去除，而在本研究中，生物降解是主要机制。
