Environmental and Water Resources Engineering Division, Indian Institute of Technology Madras, Chennai, 600036, India.
Easwari Engineering College, Chennai, 600089, India.
J Environ Manage. 2020 Jul 15;266:110469. doi: 10.1016/j.jenvman.2020.110469. Epub 2020 Apr 17.
This study mainly focuses on the efficiency of anodic oxidation process (Ti/Sb-SnO/PbO as anode and stainless steel as the cathode) in treating two different streams of urban wastewater, one from the influent of sequence batch reactor (WW1) and other from the effluent of constructed wetland (WW2). The effect of different operational parameters such as current density, hydraulic retention time, exposed electrode surface area, phosphorous, ammonia-nitrogen, nitrates, and coliform bacteria was studied. For an optimized current density of 30 mA/cm and an electrode surface area of 30 cm, almost complete removal of COD and ammonia-nitrogen were achieved with both wastewaters (WW1 & WW2), while in case of phosphorous, 50% and 98% removal efficiencies were observed. Electrode deposition was analyzed using SEM-EDS and XRD, which confirms the presence of calcium and magnesium phosphates on the surface on the anode, which attributes to the phosphate removal. Electrochemical disinfection studies showed that complete inactivation of bacteria takes place within 30 min for WW1 and 60 min for WW2, and the cell morphological changes were studied using SEM analysis. Degradation of different micropollutants present in the wastewaters was evaluated with the aid of GC-MS. ICP - MS analysis confirmed that there was no leaching of lead from the anode surface, and the lead which is already present in the wastewater gets reduced to a permissible level, which further increases the treatment efficiency. Hence cleaner and comprehensive treatment of real urban wastewaters through anodic oxidation process was successfully demonstrated in this work.
本研究主要关注阳极氧化工艺（Ti/Sb-SnO/PbO 作为阳极，不锈钢作为阴极）处理两种不同城市污水的效率，一种来自序批式反应器的进水（WW1），另一种来自人工湿地的出水（WW2）。研究了不同操作参数（电流密度、水力停留时间、暴露电极表面积、磷、氨氮、硝酸盐和大肠菌群）的影响。在优化的电流密度为 30 mA/cm 和电极表面积为 30 cm 的条件下，两种废水（WW1 和 WW2）的 COD 和氨氮几乎都能完全去除，而磷的去除效率分别为 50%和 98%。通过扫描电子显微镜-能谱仪（SEM-EDS）和 X 射线衍射（XRD）分析电极沉积，证实了阳极表面存在钙和镁磷酸盐，这是导致磷去除的原因。电化学消毒研究表明，对于 WW1，细菌完全失活发生在 30 分钟内，对于 WW2，细菌完全失活发生在 60 分钟内，并通过 SEM 分析研究了细胞形态变化。借助 GC-MS 评估了废水中存在的不同微量污染物的降解情况。ICP-MS 分析证实，阳极表面没有铅浸出，废水中已有的铅被还原到允许的水平，从而进一步提高了处理效率。因此，本工作成功地证明了通过阳极氧化工艺对实际城市污水进行更清洁、更全面的处理。
