School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University), Guangzhou, 510275, China.
Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, USA.
Water Res. 2017 Aug 1;119:12-20. doi: 10.1016/j.watres.2017.04.040. Epub 2017 Apr 17.
Sulfamethoxazole (SMX) is one of the most commonly used antibiotics. SMX degradation in sulfate-reducing bacteria (SRB) sludge systems has not been reported so far. This research investigated the SMX degradation using SRB sludge in a sulfate-reducing up-flow sludge bed reactor. Moreover, the mechanisms and kinetics of SMX removal were also investigated using SRB sludge via a series of batch experiments. The results showed that SMX removal was characterized by a rapid sorption onto SRB sludge, and desorption from SRB sludge to aqueous phase until achieving equilibrium, and then followed by slow biodegradation. Biodegradation was the dominant route for SMX removal. The sorption process conformed well to a pseudo-second-order kinetic model, meaning that the sorption occurred primarily via a chemical sorption process. The removal of SMX followed the pseudo-zero-order kinetic model with a specific removal rate of 13.2 ± 0.1 μg/L/d at initial SMX concentration 100 μg/L in batch tests. Based on the analysis of metabolites, most of the SMX biotransformation products' structures altered in the isoxazole ring, which were significantly different from that produced by aerobic and anaerobic sludge systems. Thus, SRB sludge system could play an important role in SMX biodegradation, especially in Sulfate-reduction Autotrophic denitrification and Nitrification Integrated (SANI) process for sewage treatment.
磺胺甲恶唑（SMX）是最常用的抗生素之一。迄今为止，尚未有关于硫酸盐还原菌（SRB）污泥系统中 SMX 降解的报道。本研究在硫酸盐还原上流污泥床反应器中使用 SRB 污泥研究了 SMX 的降解。此外，还通过一系列批处理实验，利用 SRB 污泥研究了 SMX 去除的机制和动力学。结果表明，SMX 的去除主要通过快速吸附到 SRB 污泥上，然后从 SRB 污泥解吸到水相直到达到平衡，然后再进行缓慢的生物降解。生物降解是 SMX 去除的主要途径。吸附过程符合伪二级动力学模型，这意味着吸附主要通过化学吸附过程发生。在初始 SMX 浓度为 100μg/L 的批处理试验中，SMX 的去除遵循拟零级动力学模型，特定去除率为 13.2±0.1μg/L/d。基于代谢物的分析，大多数 SMX 生物转化产物的结构在异恶唑环中发生了改变，这与好氧和厌氧污泥系统产生的产物明显不同。因此，SRB 污泥系统在 SMX 的生物降解中可能发挥重要作用，特别是在用于污水处理的硫酸盐还原自养反硝化和硝化一体化（SANI）工艺中。
