Nuruzzaman Md, Anwar A H M Faisal, Sarukkalige Ranjan
School of Civil and Mechanical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
School of Civil and Mechanical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
J Environ Manage. 2023 Jul 1;337:117746. doi: 10.1016/j.jenvman.2023.117746. Epub 2023 Mar 21.
Floating Treatment Wetland (FTW) is a cost-effective and easy-to-retrofit device for stormwater treatment. Its treatment efficiency largely depends on the fraction of inflow entering FTW and the residence time within it. Thus hydrodynamics play a crucial role, which is affected by the design configurations of FTW and stormwater pond. Despite a spike in research on FTWs, very little is known about how various design configurations affect treatment efficiency by an FTW. Our study hypothesizes that relative positions of FTW geometry, FTW position and pond inlet-outlet have impact on the hydrodynamics and as a consequence, treatment efficiency. To explore these design features, we employed computational fluid dynamics (CFD) modeling conducted in ANSYS Fluent, validated by experimental data to examine the impact of the aforementioned design features. The results revealed that circular FTW geometry positioned near inlet coupled with center inlet-side outlet configuration achieved the highest removal (94.8%) for a non-dimensional removal rate of kt = 20 (k is the first order removal rate in per day, t is the nominal hydraulic residence time of the pond in days). Far side inlet-side outlet configuration performed the worst due to profound promotion of short-circuiting. FTW positioned near inlet performed better (61.8% mass removal on an average) than center (42.7%) and near outlet positions (54.1%) for kt = 20. Sensitivity analysis revealed that the treatment efficiency is most sensitive to inlet-outlet configurations. The design implications of this study will help practitioners achieving better water quality and ecological improvement goals.
浮动处理湿地（FTW）是一种用于雨水处理的经济高效且易于改造的装置。其处理效率在很大程度上取决于进入FTW的入流比例及其在其中的停留时间。因此，水动力起着至关重要的作用，而这又受到FTW和雨水池塘设计配置的影响。尽管对FTW的研究激增，但对于各种设计配置如何影响FTW的处理效率却知之甚少。我们的研究假设FTW几何形状的相对位置、FTW位置和池塘进出口对水动力有影响，进而影响处理效率。为了探究这些设计特征，我们采用了在ANSYS Fluent中进行的计算流体动力学（CFD）建模，并通过实验数据进行验证，以检验上述设计特征的影响。结果表明，对于无量纲去除率kt = 20（k是每天的一级去除率，t是池塘的名义水力停留时间，单位为天），靠近进水口设置的圆形FTW几何形状与中心进水 - 侧边出水配置实现了最高去除率（94.8%）。远侧边进水 - 侧边出水配置由于极大地促进了短路，表现最差。对于kt = 20，靠近进水口设置的FTW表现优于中心位置（平均质量去除率为42.7%）和靠近出水口位置（54.1%），平均去除率为61.8%。敏感性分析表明，处理效率对进出口配置最为敏感。本研究的设计启示将有助于从业者实现更好的水质和生态改善目标。
