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Anodic oxidation is a viable technology for the degradation of contaminants such as Ni-ethylenediaminetetraacetic acid (Ni-EDTA) complexes which are commonly found in wastewaters from the electroless plating industry. In an anodic oxidation process, the convective transport of the contaminant to the anode, which is affected by the hydrodynamic characteristics of the reactor and geometry of the electrodes, is crucial to the overall contaminant removal efficiency. In this work, a three-dimensional computational fluid dynamics (CFD) model was successfully developed to investigate flow behavior and its impact on the concentration profiles of Ni-EDTA complexes in a flow-through reactor during anodic oxidation of a synthetic wastewater containing these complexes. The CFD model was used to investigate the effect of electrode aperture size and shape on Ni-EDTA degradation with both simulation and experimental results indicating that, for the investigated system, the reduction of electrode aperture size enhanced the Ni-EDTA degradation rate by up to 1.4 times due to the increased rate of Ni-EDTA mass transfer to the electrode surface. A woven electrode exhibited the highest rate of Ni-EDTA degradation of the different anodes examined with the good performance in this case attributed particularly to the much more uniform Ni-EDTA concentration distribution and surface shear stress on the electrode surface. The CFD model developed in this study provided insights into the effect of electrode aperture geometry on mass transfer and subsequent contaminant removal efficiency and can be used more broadly for the optimization of anode design and reactor operation in electrochemical advanced oxidation processes.

This paper applied the fuzzy comprehensive evaluation (FCE) technique and analytic hierarchy process (AHP) procedure to evaluate the wastewater treatment for enterprises. Based on the characteristics of wastewater treatment for enterprises in Taihu basin, an evaluating index system was established for enterprise and analysis hierarchy process method was applied to determine index weight. Then the AHP and FCE methods were combined to validate the wastewater treatment level of 3 representative enterprises. The results show that the evaluation grade of enterprise 1, enterprise 2 and enterprise 3 was middle, good and excellent, respectively. Finally, the scores of 3 enterprises were calculated according to the hundred-mark system, and enterprise 3 has the highest wastewater treatment level, followed by enterprise 2 and enterprises 1. The application of this work can make the evaluation results more scientific and accurate. It is expected that this work may serve as an assistance tool for managers of enterprise in improving the wastewater treatment level.