| 摘要: | 南化淨水場(以下簡稱南化場)水源取自南化水庫，其位於臺南市南化區曾文溪支流後堀溪上，其水源除本身集水區外，另由高屏溪支流旗山溪設甲仙堰於豐水期越域引水，以輸水隧道將旗山溪豐水期多餘之水量引入南化水庫運用，提高南化水庫之供水量。
南化水庫原水進入場內調節池進行水量調整及沉澱降低濁度後，於分水井進行前加氯(次氯酸鈉)去除(氧化)氨氮、鐵及錳等物質，接著進入快混池於原水中加入混凝劑(108年第4季前為半場聚氯化鋁，半場氯化鐵，之後改全場添加氯化鐵)，藉由水躍達成快速混合作用。快混後之原水進入膠羽沉澱池，產生膠羽顆粒，藉由膠羽機緩慢攪拌，經膠凝作用使小膠羽逐漸結合較大且重之膠羽，形成膠羽之原水，在足夠滯留時間下藉由重力之沉降作用、分離原水中較大之膠羽顆粒及懸浮固體。沉澱後原水進入快濾池將細小懸浮物質及微生物等藉由濾料之截留、沉澱、吸附及化學反應等作用加以去除，並藉反沖洗機制維持濾料之清潔。快濾後之清水經後加次氯酸鈉消毒進入清水池，主要功能係維持淨水場穩定出水量之調節能力及確保消毒接觸時間及增加消毒效果。近年來南化水庫於4~6月期間，其原水中還原性物質如鐵、錳與氨氮經檢測後常有升高之趨勢(原水中鐵0.2~0.6 mg/L，錳0.1~1.0 mg/L，氨氮0.2~1.2 mg/L)，導致南化場處理水質不佳。為因應此情形，南化場於調節池消能井添加預氯，增加氧化反應接觸時間，雖能符合飲用水水質標準，惟仍無法有效降低清水中鐵、錳與氨氮，致原水水質不佳時，仍偶有用戶抱怨之情形。為維護飲用水安全及符合飲用水水質標準，於特殊時期針對淨水操作做綜合性診斷及最適操作建置，以使淨水場清水水質符合規定，並達到最佳化操作之目的，爰辦理本計畫。
When the abnormal raw water with high iron/manganese and ammonia nitrogen occurs in the Nanhua water purification plant, a large amount of pre-chlorination will be carried out in the rapid mixing tank. Even, pre-chlorination treatment will be added in front of the adjustment tank or water diversion well. The chemical used is NaOCl, which is used to oxidize the high concentration of manganese and ammonia nitrogen in the abnormal raw water. But if there is a high TOC concentration in the raw water, the addition of high doses of sodium hypochlorite in the water may cause the risk of disinfection by-products. The purpose of this research project is to improve the treatment effect of abnormal raw water containing high manganese and high ammonia nitrogen and to avoid the formation of disinfection by-products under the condition of high TOC raw water. The raw water used in the study was taken from Nanhua Reservoir. Since no special water quality occurred during the experiment, ammonium chloride and manganous chloride were added to the raw water of Nanhua to simulate the abnormal raw water quality conditions of high manganese and high ammonia nitrogen. The experimental results show that the removal effect of ammonia nitrogen is best with NaOCl, while KMnO4 has the best removal effect for total manganese. In this project, KMnO4 is combined with NaOCl to treat raw water containing high manganese and high ammonia nitrogen, and it is found that KMnO4 combined with NaOCl can play their respective functions and remove most of the total manganese and ammonia nitrogen in the raw water at the same time. The results of laboratory bottle-cup test evaluation and module test evaluation also show that manganese sand has a very good effect on the removal of manganese in water, especially the water purification performance of regenerated manganese sand is quite good, but the effect of using new manganese sand is quite good. But it should be noted that regenerated manganese sand must be fully washed before use to achieve the best treatment performance. According to the analysis results of TOC and EEFM, if the water contains organic matter, the use of KMnO4 combined with NaOCl can remove organic matter better than NaOCl alone. However, for the removal of organic matter, the operating efficiency of coagulation and sedimentation is still the main factor. When the residual amount of organic matter in the filtered water is higher, the subsequent generation potential of DBPs will also be higher. From the analysis of the removal effect of organic matter in the mold factory test, the results also show that the use of KMnO4 combined with NaOCl can remove organic matter better than NaOCl alone. For filtration, the use of manganese sand filter material will be better than the use of pure silica sand. Therefore, this plan suggests that the process of oxidation to KMnO4 combined with NaOCl followed by manganese sand filtration can not only effectively remove manganese and ammonia nitrogen in water, but also reduce the content of organic matter in water and reduce the formation of disinfection by-products. |
