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    Please use this identifier to cite or link to this item: http://ir.cnu.edu.tw/handle/310902800/28554


    標題: Effects of porosity on flow of free water surface constructed wetland in a physical model
    作者: Chyan, Jih-Ming
    Jacobe Tan, Fibor
    Chen, I-Ming
    Lin, Chien-Jung
    Bantillo Senoro, Delia
    Camino Luna, Mario Paul
    貢獻者: 環境資源管理系
    關鍵字: Constructed wetlands
    Free water surface (FWS) flow
    Porosity
    Mean residence time
    Hydraulic efficiency
    日期: 2014-01
    上傳時間: 2015-05-06 21:20:30 (UTC+8)
    出版者: Taylor & Francis Inc
    摘要: Despite the widespread use of constructed wetland, the parameters of its design and their operational related parameters have not yet been clearly defined. In free water surface (FWS) flow constructed wetland (CW), emergent vegetation is a primary component in pollutant removals that alters the porosity and flow pattern of water. Based on tracer experiments in a physical model, this study investigates how porosity affects hydraulic performance parameters. Experimental results indicate that, at a rather low hydraulic loading rate (HLR), the mean residence time (tau(m)) decreases with decreasing porosity (epsilon). When the static and dynamic effects are balanced, the relation between epsilon and tau(m) becomes neutral at a high HLR. However, the Reynolds number (N-R) can accurately predict tau(m). A rather high coefficient of multiple determination for the proposed model is 0.985. This study also investigates, how the number of tanks-in-series (N) under various porosities influences the flow pattern. When vegetation is lacking, N ranges from 1.27 to 1.94. With an increasing HLR, the flow pattern in CW changes from a completely stirred tank reactor to a plug flow reactor (PFR). However, when affected by porosity, the flow approaches PFR in a larger mode implying that porosity influences the flow pattern in FWS CW. The average hydraulic efficiencies without any porosity effect are approximately 0.2. In a poorly designed FWS CW, increasing HLR does not actively modify hydraulic efficiency. Moreover, reducing the porosity from 100 to 76% increases the mean hydraulic efficiency to 0.54. Two empirical equations for the relationships of tau(m) and the actual hydraulic efficiency with N-R and the stem Reynolds number (N-R*) give CW investigators or designers to have a deeper understanding of the mean residence time and the hydraulic efficiency by RTD, N-R, and N-R*.
    關聯: Desalination and Water Treatment, v.52 n.4-6, pp.1077-1085
    Appears in Collections:[環境資源管理系(所)] 期刊論文

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