School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China.
School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China; National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology, Shanghai, 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
Chemosphere. 2021 Feb;265:129125. doi: 10.1016/j.chemosphere.2020.129125. Epub 2020 Nov 27.
Sulfamonomethoxine (SMM), as one of the most predominant antibiotics in animal wastewater, is pending for effective control to minimize its environmental risks. Transformation kinetics and pathways of SMM by UV/HO in swine wastewater were systematically investigated in this study. Direct UV photolysis (as a dominant role) and ∙OH oxidation contributed to SMM degradation in UV/HO system. The less effective reaction rate of SMM in real wastewater than synthetic wastewater (0.1-0.17 vs. ∼0.2-1.5 min, despite higher HO dosage and extended reaction time) resulted mainly from the abundant presence of conventional contaminants (indicated by COD, a notable competitor of SMM) in real wastewater. SMM degradation benefited from higher HO dosage and neutral and weak alkaline conditions. However, the effect of initial SMM concentration on SMM degradation in synthetic and real wastewater showed opposite trends, owning to the different probability of SMM molecules to interact with UV and HO in different matrices. Carbonate had an inhibitory effect on SMM degradation by scavenging ∙OH and pH-variation induced effect, while nitrate promoted SMM degradation by generating more ∙OH. The removal efficiency of SMM in real wastewater reached 91% under the reaction conditions of HO of 10 mM, reaction time of 60 min, and pH 6.7-6.9. SMM degradation pathway was proposed as hydroxylation of benzene and pyrimidine rings, and secondary amine, and the subsequent cleavage of S-N bond.
磺胺甲噁唑（SMM）作为动物废水中最主要的抗生素之一，正待有效控制以尽量减少其环境风险。本研究系统研究了 UV/HO 工艺在猪废水中对 SMM 的转化动力学和途径。直接 UV 光解（作为主要作用）和 ∙OH 氧化对 UV/HO 体系中 SMM 的降解起作用。尽管实际废水中的 HO 剂量更高，反应时间更长，但实际废水的 SMM 转化动力学比合成废水慢（0.1-0.17 与 ∼0.2-1.5 min 相比），主要是因为实际废水中存在丰富的常规污染物（以 COD 表示，SMM 的一个显著竞争物）。SMM 降解受益于更高的 HO 剂量和中性至弱碱性条件。然而，初始 SMM 浓度对合成和实际废水中 SMM 降解的影响呈现相反的趋势，这是由于 SMM 分子在不同基质中与 UV 和 HO 相互作用的概率不同所致。碳酸根通过清除 ∙OH 和 pH 变化引起的效应抑制 SMM 降解，而硝酸盐通过生成更多的 ∙OH 促进 SMM 降解。在 HO 为 10 mM、反应时间为 60 min、pH 为 6.7-6.9 的反应条件下，实际废水中 SMM 的去除效率达到 91%。提出了 SMM 的降解途径为苯环和嘧啶环的羟化，以及仲胺的生成，随后 S-N 键的断裂。
