ABSTRACT

Colloidal particles removal from water is a challenge in surface water treatment. Previously, we suggested an original technique for colloidal particles separation from water based on physical flow manipulation by an oscillating device. Laboratory experiments and 2D numerical simulation indicated that this technology enhances colloidal particles grouping and enables their rapid, simultaneous aggregation and sedimentation. The 2D model used in that study was unable to fully elucidate the grouping mechanism, settling pattern, or particle trajectories. Here, we extended the numerical simulation from 2D to 3D and examined the system’s distinctive flow field. The flow field was solved with computational fluid dynamics (CFD) simulations in the commercial ANSYS Fluent code and validated by dye injection experiments. The sedimentation patterns could nicely be explained by the computational results. This explanation was strengthened by two-dimensional population balance model simulations, which showed that particles aggregated in two zones trailing the paddle edges. Additionally, the results indicate significantly higher TKE values and faster upward vertical velocities at the higher oscillating frequency, which explains the different sedimentation patterns and removal efficiencies generated by the different oscillation frequencies. The use of 3D numerical simulations will help to better understand and further optimize this novel technology.

摘要

从水中去除胶体颗粒是地表水处理中的一个挑战。以前，我们提出了一种基于振荡设备进行物理流控制的从水中分离胶体颗粒的原始技术。实验室实验和2D数值模拟表明，该技术可增强胶体颗粒的分组，并使其快速，同时聚集和沉降。该研究中使用的2D模型无法完全阐明分组机制，沉降模式或粒子轨迹。在这里，我们将数值模拟从2D扩展到3D，并检查了系统独特的流场。通过商业ANSYS Fluent代码中的计算流体动力学（CFD）模拟解决了流场问题，并通过染料注入实验对其进行了验证。计算结果可以很好地解释沉积模式。二维人口平衡模型模拟进一步加强了这种解释，该模拟表明颗粒聚集在桨边缘后面的两个区域中。此外，结果表明，在较高的振荡频率下，TKE值明显较高，垂直速度更快，这解释了不同的沉积模式和不同的振荡频率产生的去除效率。3D数值模拟的使用将有助于更好地理解和进一步优化这一新技术。此外，结果表明，在较高的振荡频率下，TKE值明显较高，垂直速度更快，这说明了不同的沉积模式和由不同的振荡频率产生的去除效率。3D数值模拟的使用将有助于更好地理解和进一步优化这一新技术。此外，结果表明，在较高的振荡频率下，TKE值明显较高，垂直速度更快，这解释了不同的沉积模式和不同的振荡频率产生的去除效率。3D数值模拟的使用将有助于更好地理解和进一步优化这一新技术。