UV/H_(2)O_(2)对海水养殖废水中磺胺甲恶唑去除条件优化与降解机制分析

Optimization of Removal Conditions and Degradation Mechanism of Sulfamethoxazole in Mariculture Wastewater by UV/H_(2)O_(2)

磺胺甲恶唑(Sulfamethoxazole,SMX)是海水养殖过程中常用的抗生素,其在养殖废水中频繁检出,因此废水排放前需要进行有效处理。本研究应用紫外/过氧化氢(UV/H_(2)O_(2))高级氧化工艺,以含SMX的海水养殖废水为处理对象,系统探究工艺处理SMX过程中的影响因素、降解动力学,分析SMX降解规律和途径。结果表明,在SMX初始浓度为10 mg·L^(-1)时,UV强度为1.1 mW·cm、H_(2)O_(2)浓度为2 mmol·L^(-1)、pH为5时,20 min后SMX去除率可达99%以上。UV光解和·OH氧化在降解SMX过程占主导作用,降解过程遵循准一级动力学模型(R^(2)≥0.99)。氯离子和碳酸根离子能够竞争·OH并导致pH变化,进而抑制SMX去除效率,硝酸根离子在UV照射下形成内滤膜,减弱光照从而抑制SMX去除速率。SMX降解过程中产生的中间产物使得处理体系生物毒性上升,随着处理时间的延长,生物毒性下降;工艺中的·OH可有效提高SMX的矿化度。SMX降解途径主要包含磺酰胺键断裂、羟基取代和氨基的氧化作用。可见,UV/H_(2)O_(2)工艺可有效去除和矿化海水养殖废水中的磺胺甲恶唑,降低扩散风险,在养殖污染控制中具有很好的应用潜力。

Sulfamethoxazole(SMX)is a commonly used antibiotic in mariculture and is frequently detected in aquaculture wastewater.Thus,wastewater required to be effectively treated before discharge.In this study,the advanced oxidation process of ultraviolet/hydrogen peroxide(UV/H_(2)O_(2))was applied to treat the mariculture wastewater containing SMX.The influencing factors and degradation kinetics in the process of SMX treatment were systematically explored,and the degradation patterns and pathways of SMX were analyzed.The results showed that the removal rate of SMX could reach 99%after 20 min when the initial concentration of SMX was 10 mg·L^(-1),UV intensity was 1.1 mW·cm,H_(2)O_(2)concentration was 2 mmol·L^(-1)and pH was 5.UV photolysis and·OH oxidation played a dominant role in the degradation of SMX,and the degradation process followed a quasi-first-order kinetic model(R^(2)≥0.99).The presence of chloride ion and carbonate ion can compete with OH and cause pH changes,thus inhibiting the removal efficiency of SMX.Nitrate ion forms an internal filtration membrane under UV irradiation and weakens light,thus inhibiting the removal rate of SMX.The intermediates produced during the degradation of SMX increased the biotoxicity of the treatment system,and decreased with the extension of treatment time.·OH in the process can effectively improve the mineralization of SMX.SMX degradation pathway mainly includes sulfamide bond breaking,hydroxyl substitution and amino oxidation.Therefore,UV/H_(2)O_(2)process can effectively remove and mineralize antibiotics in mariculture wastewater,reduce the risk of diffusion,and has a good application potential in aquaculture pollution control.