Electrochemical denitrification of highly contaminated actual nitrate wastewater by Ti/RuO2 anode and iron cathode
Electrochemical denitrification of highly contaminated actual nitrate wastewater by Ti/RuO2 anode and iron cathode
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DOI：
10.1016/j.cej.2019.122065
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发表时间：
2020-04-15
影响因子：
15.1
通讯作者：
Srivastava, Vimal Chandra
中科院分区：
文献类型：
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作者：
Chauhan, Rohit;Srivastava, Vimal Chandra
反硝化过程的主要目的是通过还原NO3-沿着同时氧化副产物如NH 4+和NO2-来获得作为最终产物的N-2。以Ti/RuO 2为阳极，Fe为阴极，对实际高浓度硝酸根废水进行处理。研究了电流密度（J = 142.86-428.57 A/m2）、废水pH值（4-12）和时间（t = 15-180 min）对含硝酸盐（NO3-）、铵离子（NH 4+）和氯离子的真实的工业废水的电化学还原和氧化的主要操作参数。应用法拉第定律计算了该过程中的比能耗（SEC）。当J = 214.29 A/m（2）时，反应180 min后NO3-还原效率最高，接近46%，SEC = 149.7 kWh/kg。在pH = 12、J = 285.71 A/m（2）、SEC = 220.7 kWh/kg NO3-还原时，总氮（TN）去除率最高，接近51%。建立了EC同时还原NO3-和氧化NH 4+、NO2-的反应机理和途径。采用场发射扫描电子显微镜（FE-SEM）结合能量色散X射线（EDX）、原子力显微镜（AFM）和X射线衍射（XRD）对废水处理前后的电极进行了表征。采用气相色谱-质谱联用（GC/MS）对反应中间体进行了鉴定。在实验室规模反应器的基础上对该废水进行了运行成本分析，并与以前报道的其他工业废水进行了比较。有趣的是，在处理过程中没有产生污泥和/或浮渣。这项研究提供了更好地了解NO3-的还原以及副产物的进一步氧化。
The main objective of denitrification process is to obtain N-2 as the final product by reduction of NO3- along with simultaneous oxidation of by-products like NH4+ and NO2-. In this study, Ti/RuO2 and Fe were used as anode and cathode, respectively, for the treatment of actual wastewater containing high concentration of nitrate ion. The current density (J = 142.86-428.57 A/m(2)), wastewater pH (4-12) and time (t = 15-180 min) were the main studied operating parameters for the electrochemical (EC) reduction and oxidation of real industrial wastewater containing nitrate (NO3-), ammonium ion (NH4+) and chloride. Faraday law was applied for the calculation of specific energy consumption (SEC) during the process. The maximum NO3- reduction efficiency of approximate to 46% was obtained at J = 214.29 A/m(2) after 180 min with SEC = 149.7 kWh/kg NO3- reduced. Maximum total nitrogen (TN) removal efficiency of approximate to 51% was obtained at pH = 12 and J = 285.71 A/m(2) with SEC = 220.7 kWh/kg NO3- reduced. The reaction mechanism and pathway was established for the EC reduction of NO3- and oxidation of NH4+ and NO2- simultaneously. Field emission scanning electron microscope (FE-SEM) coupled with energy dispersed X-ray (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD) were used for the characterization of electrodes before and after wastewater treatment. Reaction intermediates were identified by using gas chromatograph coupled with mass spectroscopy (GC/MS). Operational cost analysis for this wastewater has been done on the basis of lab scale reactor and compared with previously reported for other industrial wastewater. Interestingly no sludge and/or scum was produced during the treatment. This study provides better understanding of the reduction of NO3- as well as further oxidation of by-products.