UCD Dooge Centre for Water Resources Research, School of Civil Engineering, University College Dublin, Belfield, Newstead Building, Dublin 4, Ireland.
J Environ Manage. 2024 Feb;351:119776. doi: 10.1016/j.jenvman.2023.119776. Epub 2023 Dec 12.
Baffled constructed wetlands (CWs) offer a promising solution to address low hydraulic efficiency in traditional CWs. However, there is a research gap in the field regarding the optimal length and quantity of baffles, and their comprehensive effects on hydraulic efficiency. This study is the first CFD-based assessment to comprehensively investigate the combined influence of baffle length and the number of baffles on the hydraulic efficiency of CWs. Using OpenFOAM simulations at a laboratory scale, various baffle configurations were examined with lengths ranging from 0.4 m to 0.58 m and baffle numbers varying from 0 to 11. Experimental tracer tests were conducted to validate the simulations. The high correlation coefficient (R) between the tracer test results and simulations (ranging between 0.84 and 0.93) further underscores the reliability of the findings. Residence time distributions (RTDs) were derived from the temporal evolution of the outlet concentration of a tracer. The results indicate that augmenting the number of baffles under a fixed baffle length has a greater impact on the RTD curves, causing a backward displacement of the peak time. However, when the number of baffles is three or fewer, extending the baffle length does not significantly affect the RTD. When the baffle length is held constant at 0.58 m, there is a 58% enhancement in hydraulic efficiency as the number of baffles increases from 0 to 5. However, when maintaining a constant number of 11 baffles, increasing the baffle length from 0.4 to 0.5 m results in only a 5.5% improvement in hydraulic efficiency. Moreover, a generalized predictive equation for hydraulic efficiency was derived based on the CFD results and dimensional analysis. The study enhances the optimization of constructed wetland design by providing greater understanding of hydrodynamic behavior, leading to improved performance and applicability in practical environmental engineering.
困惑的人工湿地 (CWs) 为解决传统 CWs 水力效率低的问题提供了一个很有前途的解决方案。然而，在 baffled CWs 的水力效率方面，该领域存在一个研究空白，即最佳的挡板长度和数量，以及它们对水力效率的综合影响。本研究是首次基于 CFD 对挡板长度和挡板数量对 CWs 水力效率的综合影响进行全面评估。在实验室规模下使用 OpenFOAM 模拟，研究了长度从 0.4 m 到 0.58 m 不等的各种挡板配置和数量从 0 到 11 的挡板数量。进行了实验示踪剂测试来验证模拟。示踪剂测试结果与模拟的高相关系数（R）（范围在 0.84 到 0.93 之间）进一步强调了结果的可靠性。停留时间分布（RTD）是从示踪剂出口浓度的时间演变中得出的。结果表明，在固定挡板长度下增加挡板数量对 RTD 曲线的影响更大，导致峰值时间向后移动。然而，当挡板数量为 3 个或更少时，延长挡板长度不会显著影响 RTD。当挡板长度固定在 0.58 m 时，随着挡板数量从 0 增加到 5，水力效率提高了 58%。然而，当保持 11 个挡板的数量不变时，将挡板长度从 0.4 增加到 0.5 m 只会使水力效率提高 5.5%。此外，根据 CFD 结果和量纲分析，推导出了水力效率的通用预测方程。本研究通过提供对水动力行为的更深入理解，增强了人工湿地设计的优化，从而提高了实际环境工程中的性能和适用性。
