曝氣作用對表面流動式人工濕地水力特性之影響

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標題:	曝氣作用對表面流動式人工濕地水力特性之影響 Effect of Artificial Aeration on Hydraulic Characteristics of Surface Flow Constructed Wetlands
作者:	曾郁帆
貢獻者:	環境資源管理系錢紀銘
關鍵字:	This research is mainly to explore the effects of aeration and rectification on hydraulic characteristics of free water surface (FWS) constructed wetlands (CW). The experiment included three stages in this study and the theoretical hydraulic retention time (HRT) was 2.2 d, 1.0 d, 0.5 d, respectively. The aeration rates were 0. 0 L/min, 6.66 L/min, 16.0 L/min, and 32.0 L/min. In addition, the study also discussed the effect of the rectifier on the hydraulic characteristics of FWS CW with artificial aeration. To evaluate the changes of hydraulic characteristics of FWS CW with aeration and rectification, the hydraulic parameters are mainly hydraulic efficiency, extent of short-circuiting, variance, and Residence time distribution (RTD). From the results of the study, a low flow rate (HRT = 2.2 d) and a high aeration rate (= 32.0 L / min) would reduce the actual hydraulic retention time from 2.4 d without aeration to 1.2 d. However, n no significant differences were observed in the experimental conditions of short HRT with different aeration rate. A higher variance of RTD in FWS CW indicated a weaker vortex existed in FWS CW, implying a less influence of vortex on the hydraulics of FWS CW. Based the experimental results, when the flow rate was 90 L/min, a greater variations implied a weaker vortex affecting the hydraulics of FWS CW. When the flow rate increased to 197 L / min and 394 L / min, lower variances demonstrated stronger vortex affecting FWS CW. As for the extent of short-circuiting, it variates between 0 and 1and a smaller one implied a severe short-circuiting flow. When HRT was 2.2 d, the short-circuiting was above 0.6 for different aeration rate, implying that a low flow was not easy to induced worse short-flow conditions. The study also found that when the HRT was 1.0 d, the aeration was 6.7 L / min, the actual hydraulic retention time decreased from 1.0 d to 0.5 d while HRT = 0.5 d and aeration = 6.7 L / min, the actual hydraulic retention time decreased from 0.5 d to 0.2 d. It indicated that the aeration effect will affect the actual hydraulic retention time. As a matter of factor, the actual hydraulic retention time would affect the time of highest tracer concentration. Based on the above discussion, it concluded that the aeration affected the hydraulic characteristics of FWS CW. In the stage C, the extent of short-circuiting distributed between 0.48 and 0.68 while, in the stage D, the range was 0.46-0.53. A lower extent of short-circuiting of stage D indicated that it induced a stronger in short-flow situation without rectification. At high influent flow rates, HRT without a rectifier is compared to those in a rectified FWS CW. The reason is that when there is no rectification, it would induced a serious disturbance in the water, thus prolonging the HRT. It concluded that the honeycomb rectifier has a certain effect on the aeration generated by the system aeration. 表面流動式人工濕地曝氣模式水力特性水力效率 Free water surface flow constructed wetland Aeration mode、Hydraulic characteristics Hydraulic efficiency
日期:	2019
上傳時間:	2020-12-09 14:47:43 (UTC+8)
摘要:	本研究主要為探討曝氣整流作用對表面流動式 (Free water surface；FWS) 人工濕地 (Constructed wetland；CW) 水力特性之影響，在本研究中設計四種試程，其A試程為理論水力停留時間 Hydraulic retention time HRT) 分別為 2.2 d 、 B 試程為 HRT= 1.0 d 、試程為 HRT= 0.5 d 、 D 試程為無放置整流裝置，其 HRT=0.5 d 而曝氣量以 0 .0 L/min 、 6.66 L/min 、 16 .0 L/min 以及 32 .0 L/min 在各試程中進行研究探討。另外，本研究亦探討整流器對曝氣效應作用下 FWS CW 水力特性的影響。本研究的水力參數主要藉由水力效率 Hydraulic efficiency 、短流度 Extent of short-circuiting 、變異數、濃度歷時分布函數 (Residence time distribution，RTD)等參數來評估曝氣整流作用對 FWS CW 水力特性的影響。從研究結果可知低流量 (HRT=2.2 d) 高曝氣量 32 .0 L/min 時，曝氣整流作用將使實際水力停留時間由無曝氣的 2.4 d 降為 1.2 d 而曝氣整流作用對短 HRT 的影響較無明顯差異。而從變異數可知，變異數越大表示受到的內渦流特性的影響較不明顯，當流量為 90 L/min 時越高的曝氣量，變異數的差異就越大，而當流量為 197 L/min 及 394 L/min 時，不論曝氣量的大小，變異數與低流量 (HRT=2.2 d) 相比較小，由此可知，當低流量會比高流量更容易出現內渦流特性。短流度方面，短流度一般會 ii 介於介於00與與11之間，其值越小則代表短流情形越嚴之間，其值越小則代表短流情形越嚴重，當低流量重，當低流量 (HRT=2.2 d) (HRT=2.2 d) 時，不同曝氣量之短流度皆在時，不同曝氣量之短流度皆在0.60.6以上，從中得知低流以上，從中得知低流量時曝氣量較不易產生短流情形。研究中還量時曝氣量較不易產生短流情形。研究中還發現發現當當HRTHRT為為11.0 .0 dd曝氣曝氣量為量為6.6.77 L/minL/min時，實際水力停留時間時，實際水力停留時間從從1.0 d1.0 d縮短至縮短至0.5 d0.5 d，而當，而當HRTHRT為為0.5 d0.5 d曝氣量為曝氣量為6.7 L/min6.7 L/min時，實際水力停留時間從時，實際水力停留時間從0.5 d0.5 d縮點至縮點至0.2 0.2 dd，，由此可知由此可知曝氣曝氣作用作用會影響實際水力停留時間，而實際水力停留時會影響實際水力停留時間，而實際水力停留時間會影響到間會影響到濃度歷時分布污染物最高濃度的發生時間 (ttpp))。。綜合前述，曝氣作用會對表面流動式人工濕地的水力特性產生影響。在試程C中短流度介於0.48-0.68之間，而在試程D中，短流度介於0.46-0.53之間，D試程的S與試程C相比較低，由此可知在高流量下，無整流作用的短流情形會更嚴重。而在高流量下，無在高流量下，無放置放置整整流管流管的的HRTHRT與有整流作用的與有整流作用的HRTHRT相比，從相比，從0.23 d0.23 d延長至延長至0.26 d0.26 d，由，由此可知，整流作用會對此可知，整流作用會對HRTHRT產生影響，其原因為無整流時會造成水產生影響，其原因為無整流時會造成水中較嚴重的擾流情形中較嚴重的擾流情形所以延長了所以延長了HRTHRT。。綜合上述蜂巢式整流管在系統中曝氣產生的擾流有一定的緩解作用。
關聯:	電子全文公開日期：2021-07-31 學年度：107，65頁
顯示於類別:	[環境資源管理系(所)] 博碩士論文

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