中压紫外/甲酸盐还原体系对硝酸盐的去除效能及机制  

Removal efficiency and mechanism of nitrate in the medium pressure ultraviolet/formate system

作　　者：任鹏飞 周建华 张锐 陈贻龙 张欣然 REN Pengfei;ZHOU Jianhua;ZHANG Rui;CHEN Yilong;ZHANG Xinran(Guangzhou Municipal Engineering Design&Research Institute,Guangzhou 510060,China;School of Environmental Science and Engineering,Sun Yat-sen University,Guangzhou 510060,China)

机构地区：[1]广州市市政工程设计研究总院有限公司,广州510006 [2]中山大学环境科学与工程学院,广州510006

出　　处：《环境工程学报》2024年第9期2409-2417,共9页Chinese Journal of Environmental Engineering

基　　金：国家自然科学基金面上项目(22376230);广州市市政工程设计研究总院有限公司科技开发项目(KY-2021-020)。

摘　　要：研究了中压紫外/甲酸盐(MPUV/HCOO^(−))还原体系对硝酸盐(NO_(3)^(−))的去除效能和机制。结果表明,MPUV/HCOO^(−)体系的NO_(3)^(−)去除效果显著高于单独MPUV光解。当NO_(3)^(−)初始浓度为0.1 mmol·L^(−1),HCOO^(−)投加量为1 mmol·L^(−1)时,MPUV/HCOO^(−)体系中NO_(3)^(−)的伪一级动力学降解速率(5.7×10^(−3)min^(−1))是单独MPUV(1.0×10^(−3)min^(−1))光解的5.7倍,且HCOO^(−)的投加使得120 min后NO_(3)^(−)还原率由13.7%提升至44.1%。增大紫外光强和弱碱性pH环境均有利于NO_(3)^(−)降解。该研究认为,中压紫外直接光解NO_(3)^(−)以及由HCOO^(−)转化生成的二氧化碳阴离子自由基(CO_(2)^(·−))介导的还原过程被认为共同促进了NO_(3)^(−)的还原效率。利用激光闪光光解技术,首次定量了CO_(2)^(·−)与NO_(3)^(−)和NO_(2)^(−)的二级反应速率常数分别为1.57×106 L·(mol·s)−1和9.12×10^(7)L·(mol·s)^(−1)。MPUV/HCOO^(−)体系将硝酸盐转化为亚硝酸盐,补充投加过氧化氢促进CO_(2)^(·−)的生成,CO_(2)^(·−)与亚硝酸盐反应进一步生成气态氮(氮气、氧化亚氮等)从水中脱除。在污水处理中,借助中压紫外消毒和生物处理系统中剩余碳源甲酸盐构建中压紫外/甲酸盐体系,有望强化污水深度脱氮,具有良好的应用前景。In this study,the nitrate removal efficiency and mechanism in the combination of medium pressure ultraviolet and formate(MPUV/HCOO^(−))system was investigated.The results showed that the nitrate removal efficiency in the MPUV/HCOO^(−)system was significantly higher than that of MPUV photolysis alone.When the initial NO_(3)^(−)concentration was 0.1 mmol·L^(−1)and the HCOO^(−)dosage was 1 mmol·L^(−1),the pseudo-first-order degradation rate of NO_(3)^(−)in the MPUV/HCOO^(−)system(5.7×10^(−3)min^(−1))was 5.7 times higher than that of MPUV photolysis alone(1.0×10^(−3)min^(−1)).The addition of HCOO^(−)increased the NO_(3)^(−)reduction efficiency from 13.7%to 44.1%after 120 minutes.Increasing MPUV intensity and weakly alkaline pH condition were conducive to nitrate degradation.This study indicated that the reduction efficiency of NO_(3)^(−)was collectively enhanced by the direct photolysis of NO_(3)^(−)by MPUV and the reduction process mediated by carbon dioxide radical anion(CO_(2)^(·−))generated from HCOO^(−).Using the laser flash photolysis technology,the second order rate constants of the reaction between CO_(2)^(·−)and nitrate or CO_(2)^(·−)and nitrite were first quantified as 1.57×106 L·(mol·s)−1 or 9.12×10^(7)L·(mol·s)^(−1),respectively.The MPUV/HCOO^(−)system could lead to the transformation from NO_(3)^(−)to NO_(2)^(−),supplemental hydrogen peroxide promoted the formation of CO_(2)^(·−),which could react with NO_(2)^(−)and produce gaseous nitrogen(such as nitrogen gas and nitrous oxide)discharged from water.In wastewater treatment,the MPUV/HCOO^(−)system could be constructed with the medium pressure ultraviolet disinfection and the residual formate as the carbon source of biological treatment,which is expected to strengthen the deep denitrification of sewage and has a good application prospect.

关 键 词：硝酸盐 深度脱氮 中压紫外 甲酸盐 二氧化碳阴离子自由基(CO_(2)·) 

分 类 号：X703[环境科学与工程—环境工程]