| 摘要: | 本研究以平鎮淨水場為案例場，藉濾池反洗廢水水量與水質調查，探討淨水場反洗廢水的產量及水質特性，作為後續回收處理及再利用之依據。另一方面，本研究藉由濾池操作資料的收集，提出場內改善濾池操作之建議，以減少反洗廢水產生。 調查結果顯示，96 年哈丁式及韋勒式快濾池之反洗廢水量的平均值，分別約為4,587 CMD和9,871 CMD，以韋勒式快濾池反洗廢水為主要來源。反洗廢水量的多寡與原水和沉澱水之濁度並無明顯相關，而與各濾池的操作濾程長短有關。水質分析結果顯示，反洗廢水中的主要污染物為懸浮固體物。在一般的低原水濁度時期，哈丁式與韋勒式快濾池反洗廢水的TSS平均濃度，分別為417 mg/L與184 mg/L，其平均顆粒粒徑分佈範圍為24~57 μm。然而，在高原水濁度季節，哈丁式快濾池反洗廢水的TSS 濃度，會顯著增加至801 mg/L。此外，反洗廢水通常僅含低濃度的有機物，平均DOC濃度約為4.0 mg/L。 以預沉澱結合UF程序處理反洗廢水的實驗結果顯示，廢水濁度顆粒均能被有效去除，經沉澱處理後去除率可達93%以上，而預沉澱及UF程序處理後之濁度分別為7.9 NTU及0 NTU，但對於溶解性有機物則無明顯的去除效果，DOC的去除率僅為7%及23%，顯示反洗廢水在回收處理上，仍有進一步改善的空間。在反洗廢水減量方面，本研究提出場內濾池的檢修、改善反洗時機的判定以及控制反洗時間的長短，及回收再利用適當處理後之反洗廢水等四種源頭減量之策略，以利場內未來達廢水零排放目標。 The objectives of this study were first to investigate the quantity and quality of filter backwash wastewater (FBW) in Ping-Jan Water Treatment Plant (WTP), and then further to evaluate the possibility for treating and reusing of FBW. In addition, the strategies of reducing the quantities of FBW in this plant were also explored based on the daily information of filter operations. The survey results showed that the year average quantities of FBW from Hardinge and Wheeler filters were 4,587 and 9,871 CMD, respectively in the year of 2007. Thus, the FBW from Wheeler filters was the primary source of wastewaters in Ping-Jan WTP. In addition, the production quantity of FBW was independent on the turbidity of raw water and settled water, whereas directly correlated to the time of filter run. The results of water quality analysis indicated that the major component of pollutants in FBW was the total suspended solid (TSS). At the season of raw water with low turbidity, the TSS concentration in FBW was 417 mg/L and 184 mg/L for Hardinge filters and Wheeler filters, respectively. Also, the average particle size of TSS was in the range of 24~57 μm. However, as raw water with high turbidity, the TSS concentration in FBW from Hardinge filters was increased significantly to 801 mg/L. It was also observed that the FBW generally contained low organic contents with average DOC concentration was about 4.0 mg/L. The experimental results revealed that the turbidity in FBW could be effectively removed by pre-sedimentation followed by UF membrane process. The turbidity removal efficiency was 93% after sedimentation, and the residue turbidity after pre-sedimentation and UF process were 7.9 NTU and 0 NTU, respectively. In contrast, the DOC removal efficiency for pre-sedimentation and UF process were only 7% and 23%, respectively. These results elucidated the need of further study on water quality improvement for FBW reuse. Finally, in order to meet the goals of FBW reduction and zero discharge in Ping-Jan WTP, four strategies, including on-schedule examination and maintenance of filters, setting the new guideline for start-up filter backwashing operation, shortening the time need for backwash, and reusing and recycling of FBW with proper treatment, were recommended. |
