- 學位論文
大漢溪人工溼地污染物削減功能評估
Evaluation performance of pollutants reduction by constructed wetlands in Da-Han Creek
摘要
新北市政府於大漢溪設置8處人工溼地，前處理入流河川污染物，功能設計參數為BOD與氨氮(NH3-N)去除率。本研究人工溼地18個月計150筆水質、水量監測資料，評估人工溼地淨化水質功能，研究目的：(1)探討調查人工溼地水質、(2) 評估人工溼地削減污染物功能、及(3)檢討污染物入流負荷與去除速率之相關性。此外，水質項目為BOD、總磷(TP)、NH3-N、總氮(TN)、大腸桿菌群(TC)，以出流機率法(effluent probability method, EPM)、盒鬚圖中位數與污染物負荷量法等評估污染物削減功能。結果顯示人工溼地平均入流水量為3,712 CMD、水力停留時間為15.7 天。進流水BOD及NH3-N範圍(平均值)分別為1.4-54.5 mg/L(21.3 mg/L)及0.6-26.4 mg/L(13.6 mg/L)；出流水BOD及NH3-N範圍(平均值)則分別為0.5-21.6 mg/L(8.0 mg/L)及0.005-20.6 mg/L(13.6 mg/L)。以EPM累積50%值評估BOD與營養鹽NH3-N、TN、TP之去除率分別為60.5%、與88.1%、69.1%、79.4%， TC去除率亦高達99%以上。以盒鬚圖中位數法評估時，其去除率亦相近。人工溼地污染物去除速率(每日單位面積污染物去除量)與入流污染物負荷量呈良好線性關係，以BOD計算時其相關係數 R2= 0.93；相對地，TN、TP相關係數為R2 = 0.43-0.52；NH3-N之相關性很差(R2= 0.05)，推測其原因乃人工溼地氮循環無法計算及單元植栽無定時清除之影響所致。污染物入流負荷與去除速率相關性可作為人工溼地設計參數。綜合上述，人工溼地去除BOD及營養鹽分別達約60%與70%-80%，為削減入流河川污染負荷之有效的前處理方法。
並列摘要
The results show that the average inflow rate and hydraulic retention time were 3,712 CMD and 15.7 days, respectively. The influent (average) BOD and NH3-N ranged 1.4-54.5 mg/L (21.3 mg/L) and0.6-26.4 mg/L (13.6 mg/L), respectively. The effluent (average) BOD and NH3-N ranged 0.5-21.6 mg/L (8.0 mg/L) and 0.005-20.6 mg/L (13.6 mg/L). The removal rates of BOD, NH3-N, TN, TP and TC calculated by EPM were 60.5%, 88.1%, 69.1%, 79.4% and 99%, respectively. The removal rates calculated by the Box and whisker plot median were almost the same with that by EPM. Results indicated CWs could effectively remove BOD and nutrients nearly 60% and 70%-80%. Moreover, pollutant removal rate had a good linear relationship between inflow pollutant loading and correlation coefficient (R2) of BOD was 0.93. In contrast, correlation coefficient of TN and TP were lower as 0.43 and 0.52, respectively. And, the relationship for NH3-N was very poor with R2 value of 0.05. This might be due to the effects of nitrogen cycle and irregular harvest of the plants in CWs system. In summary, CWs could effectively remove BOD and nutrient（NH3-N, TN, TP）about 60% and 70%-80%, respectively. Therefore, CWs is an effective pretreatment of wastewater for reducing pollutants discharging into rivers.