|摘要: ||烏山頭淨水場原水取自於離槽式之烏山頭水庫，濁度經常偏低。最大出水量約240,000(CMD)，分為三期及四期淨水系統，主要淨水單元包括水躍池、膠凝池、沉澱池、快濾池、清水池及廢水處理系統。本研究以四期淨水系統為實場測試標的，此系統為單一進流口，分南、北兩沉澱池進水，經相同混凝沉澱操作條件，匯流後進入快濾池，再經清水渠進入配水管線供水。以南、北兩沉澱池同時分別加入硫酸鋁及氯化鐵不同混凝劑後所產生結果。原水的總鋁含量為0.137mg/L、清水為0.325mg/L。顯示鋁含量在添加混凝劑後的處理流程才顯現出來，可推測此鋁含量為混凝劑所貢獻。結果顯示，四期淨水系統之北沉澱池依然有較高鋁含量，沉澱後總鋁最高為0.601mg/L。相較於南池氯化鐵之添加後，沉澱後總鋁最高為0.223 mg/L，較北池減少約為2.7倍。然無論沉澱水、過濾水及清水，鋁含量皆有隨試驗時間逐漸下降之趨勢，達到降低鋁含量效益，故將混凝劑替換為氯化鐵是可行的。南、北池沉澱水在經過濾後之總鐵含量，皆降低至約0.1mg/L，遠低於飲用水水質標準之限值為0.3mg/L。另測試實場期間，調查分析西元2013年3月至6月期間各單元濁度去除率、pH、硫酸鋁混凝劑及氯氣消毒劑加藥量、鐵、錳、氨氮去除率之數據變化。結果顯示現場操作現況及水質，亦無明顯變化。藥劑單位成本方面，氯化鐵比硫酸鋁高出0.029元/M3，以出水量20萬CMD計算,增加5,800元/day。綜合上述結果並考慮法規標準及水質精緻化之前提，具有其應用之價值。|
The low-turbidity-plant raw water cleaned by Wusanto water purification is taken from the nest-type Wusanto Reservoir. The maximum water supply capacity of Wusanto water purification is 240,000 (CMD), and it consists of Three Water Purification Systems (TWPS) and Four Water Purification Systems (FWPS). The main water purification units are jump pool, gelling pond, sedimentation pond, filtration ponds, clean water pond and waste water treatment systems. In this study, FWPS is considered to be the real field test subject. FWPS has north and south sedimentation ponds, FWPS-N and FWPS-S, sharing a single inlet. After the raw water going through coagulation and sedimentation with the same operating conditions, it will be collected into the filtration ponds. Ultimately, the cleaned water is drained into distribution pipelines for water supply.For observing the Aluminum contents using different coagulants for gelling, the aluminum sulfate and the ferric chloride are added into FWPS-N and FWPS-S, respectively. The resulted Aluminum contents show that the total aluminum content of raw water is 0.137 mg/L and that of the finished gelled water is 0.325 mg /L, which means that the Aluminum content is contributed by adding coagulants. Moreover, after passing through precipitation, the highest total aluminum content measured in FWPS-N is 0.601 mg/L. With compared to the results of adding ferric chloride in FWPS-S, its highest total aluminum is 0.223 mg/L, which is lower than the highest aluminum content of FWPS-N in 2.7 times. Moreover, the experimented results show a trend that all the aluminum contents of precipitation water, filtered water and finished water are decreased gradually in time. Consequently, it is feasible to replace the general-used coagulant by ferric chloride.Additionally, the total iron contents of the filtered water in both FWPS-N and FWPS-S are lowered to about 0.1 mg/L, which is below the limited low bound of 0.3 mg/L of drinking water quality standard. Another real-field test shows that, during the period from March to June 2013, the estimates in turbidity removal rate, pH, aluminum sulfate coagulant, chlorine disinfectant dosage and the removal rates of iron, manganese and ammonia present insignificant differences in water qualities.As compared to the cost of using aluminum sulfate for water precipitation, it increases $ 0.029/M3 with using ferric chloride, i.e., it costs of $ 5,800/day under the water-supply condition of 200,000 CMD. In conclusion, by taking into account the clean effectiveness, water quality and the regulatory standards, it is valuable to utilize ferric chloride for precipitation in water clean process.