| 摘要: | 颱風期間雖然有大量雨水進入庫區，但因強風與豪雨沖刷，使上游集水區挾帶大量泥砂進入水庫，導致濁度飆高，造成淨水場操作上的困難，進而影響出水量。為解決因暴雨而產生高濁度原水問題，石門水庫改採上層分層取水工以上層取水，藉此減輕給水場進水濁度負荷。經多次切換後，於平鎮給水場淨水處理單元發現，於慢混池與濾床反沖洗時於表面出現浮泡，並有濾程縮短的現象。 本研究利用石門分層取水工(庫區)與分層取水工(水場)進場原水，使用PACl、氯化鐵與硫酸鋁進行未前加氯與前加氯瓶杯試驗試驗，探討混凝後水中有機物如TOC、DOC與SUVA等變化，藉此除試圖了解泡沫生成原因外，並探討水庫不同深度原水之前加氯及其混凝成效。 研究結果顯示，泡沫元素中以Al、O及Si比例佔總元素較多，推論其為由PACl經混凝後與水中顆粒結合產生，經實驗發現於低混凝劑量與低DOC殘餘濃度下，也有類似水場泡沫的現象出現。分層取水工(庫區)於未前加氯瓶杯下，PACl與氯化鐵對濁度去除有良好效果，硫酸鋁則較差；經前加氯後三者對於濁度移除均有提升，其中硫酸鋁能有效降低水中DOC比例，顯示硫酸鋁與DOM形成複合物，使殘餘濁度較高，此外以PACl進行混凝時，會有膠羽捕捉氣泡的現象出現。分層取水(水場)於未前加氯情況下，只有PACl能有效降低水中濁度，硫酸鋁與氯化鐵均有增加濁度的現象，推測原因應與水中溶解性物質與COC有關，前加氯後雖有提升PACl與硫酸鋁對濁度的移除，但對氯化鐵其濁度去除與膠羽沉降性反而更差的現象。Due to extreme high turbidity during typhoons or heavy rains, which resulted in difficulties in potable water treatment, the water intake well to draw water from upper levels of the reservoir was built in the Shihmen reservoir. After drawing water from the intake well, it was found that there were bubbles or foams on the surface in slow mixing tank and filter during backwash in Pingjan water treatment plant. Moreoever, the run time of filtration was significantly reduced and the filter was severely clogged. In this research, two source waters were taken from Shihmen reservoir: one was the surface water at the water intake well, the other was from Pinghan water treatment plant while switched to intake water from the mid-point of the intake well, which locates at water level 228 m. Removal of turbidity, TOC, and DOC by pre-chlorination and coagulation were investigated. The effects of types of coagulants were also examined by using PACl, ferric chloride, and aluminum sulfate. Forwater taking from the reservoir, it was found that pre-chlorination promoted the removal of turbidity. Also, aluminum sulfate can effectively reduce the ratio of DOC, which suggests that Al-DOC complex were formed, and therefore, the residual turbidity was the highest. When the water was taking from the intake well (from Pingjan water treatment plant), it was found that only PACl was effective in the removal of turbidity. After pre-chlorination, the settling of ferric flocs became worse. |
