利用生物性混凝劑對水庫區域高濁度原水處理案例研究

Turbidity Reduction Using Bio-Based Polymer

黃三益(San-Yi Huang) ； 廖偉宏(Wei-Hong Liao) ； 鄭蔚辰(Wei-Chen Chen) ； 郭玉樹(Yu-Shu Kuo)

《中華防災學刊》 6卷1期 (2014/02) Pp. 65-74

摘要

台灣地區因特殊的地理特性、集水區上游水土保持不佳及地震後地表土質鬆動等因素影響，每當夏季暴雨或颱風來臨時，洪水夾帶大量泥砂進入河川，造成水庫蓄水濁度遽升，有時甚至高達數萬濁度單位，超過自來水淨水場混凝沉澱程序處理極限，必須採取減量供水甚至停止供水的措施。因此，如何使自來水事業單位於高濁度原水期間，快速的降低原水濁度，且滿足飲用水安全標準，是目前水資源處理最重要的課題之一。飲用水事業單位為了快速解決高濁度原水的問題需進行混凝程序，目前公告可使用的混凝劑主要包括無機鹽類混凝劑及高分子凝聚劑兩類；其中，無機鹽類混凝劑處理高濁度原水效果並不理想，而高分子凝聚劑超量使用則可能影響人體健康。因此，現有之混凝劑均無法有效且快速解決高濁度原水之問題。本研究利用無毒性幾丁聚醣搭配少量無機鹽類的生物性混凝劑對澄清湖水庫現地土樣、高嶺土與渥太華標準砂所配製的高濁度原水進行杯瓶試驗，以瞭解生物性混凝劑之添加藥量對降低原水濁度之效果。試驗結果顯示，生物性混凝劑有良好的濁度去除效果；當原水濁度為52000NTU（接近莫拉克颱風後最高濁度）時，只需添加生物性混凝劑0.2 ml/L，即可使原水濁度快速降至25NTU，符合飲用水之水質標準（30NTU）；顯示生物性混凝劑應可提高淨水場混凝程序操作效率，使淨水場能在高濁度原水期間持續供水。

關鍵字

幾丁聚醣 ； 混凝劑 ； 高濁度原水 ； 濁度

並列摘要

Due to fragile geology and steep topography, extremely high turbidity, 10,000NTU or higher, water is frequently observed during a storm event. This extremely high turbidity water could lower the efficiency of water treating process in a water treatment plant or even shut down the water supply. To reduce the turbidity, two types of coagulants can be legally used in a water treating process: (1) inorganic coagulants, and (2) polymer coagulants. The former shows lower efficiency for treating high turbidity water. The latter may introduce healthy risk. Therefore, this study focuses on a bio-based polymer, or called chitosan, which is well known as non-toxic material to human beings. Three kinds of samples are used for jar tests: (1) Ottawa standard sand, (2) Kaolin soil (or Kaolinite clay), and (3) the sediment of Chengcing Lake Reservoir. The result shows that the dosage of 0.2 mg/L of the bio-based polymer can reduce the turbidity from 52,000NTU to 25NTU, which meets the drinking water standard of 30NTU during high turbidity periods. This result indicates the capability of bio-based polymer to increase the water treating efficiency for extremely high turbidity water.

並列關鍵字

chitosan ； coaglulant ； high turbidity raw water ； turbidity