In this study, non-powered hydraulic mixing with three layers of baffles and holes was evaluated as an alternative to vertical shaft impellers in a rapid mixing process through both computational fluid dynamics (CFD) modeling and field applications. From the CFD modeling, the turbulence (i.e., vortex rings) caused by excess kinetic energy between the inlet and second-layer baffle ensures rapid mixing of the coagulants throughout the total water flow and overcomes the damping effect of the components in a mixing basin. Although optimal inlet velocity needs to be investigated for sufficient mixing between coagulants and pollutants in raw water with relatively low energy consumption and maintenance costs, non-powered hydraulic mixing developed in this study was proved to create strong turbulence and can be applied in any water treatment plants that involves coagulation-flocculation processes. Based on the comparison of the water quality between two water treatment plants using identical raw water and coagulant operated from 2014 to 2016, no difference in water quality of treated water indicated that non-powered hydraulic mixing can be replaced with vertical shaft impellers, hence, both energy consumption and maintenance costs can be reduced. Further study is warranted to optimize non-powered hydraulic mixing for the tradeoff between mixing efficiency and energy consumption in the water treatment plants.

中文翻译：

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水处理厂无动力水力搅拌的计算流体动力学建模和现场应用

在这项研究中，通过计算流体动力学 (CFD) 建模和现场应用，评估了具有三层挡板和孔的无动力液压混合作为快速混合过程中垂直轴叶轮的替代方案。从 CFD 建模来看，由入口和第二层挡板之间的过量动能引起的湍流（即涡环）确保了整个水流中的混凝剂快速混合，并克服了混合池中组分的阻尼效应。尽管需要研究最佳入口速度以在相对较低的能耗和维护成本下使原水中的混凝剂和污染物充分混合，本研究中开发的无动力液压混合被证明会产生强烈的湍流，可应用于任何涉及混凝-絮凝过程的水处理厂。根据 2014 年至 2016 年运行的使用相同原水和混凝剂的两个水处理厂的水质比较，处理后的水水质没有差异表明无动力水力搅拌可以用立轴叶轮代替，因此，能源消耗和维护成本都可以降低。需要进一步研究以优化无动力液压混合，以在水处理厂中实现混合效率和能耗之间的权衡。根据 2014 年至 2016 年运行的使用相同原水和混凝剂的两个水处理厂的水质比较，处理后的水水质没有差异表明无动力水力搅拌可以用立轴叶轮代替，因此，能源消耗和维护成本都可以降低。需要进一步研究以优化无动力液压混合，以在水处理厂中实现混合效率和能耗之间的权衡。根据 2014 年至 2016 年运行的使用相同原水和混凝剂的两个水处理厂的水质比较，处理后的水水质没有差异表明无动力水力搅拌可以用立轴叶轮代替，因此，能源消耗和维护成本都可以降低。需要进一步研究以优化无动力液压混合，以在水处理厂中实现混合效率和能耗之间的权衡。