以UF(Ultrafiltration)薄膜處理表面水時，薄膜阻塞是一大問題，自然有機物(NOM)是造成阻塞之原因。本研究探討以不同前處理對親、疏水性NOM去除，與其對後續UF阻塞情形之影響。
　　首先配製高錳酸鉀作為前氧化劑，氯化鐵(FeCl3)作為混凝劑，並以藻酸代表親水性有機物，腐植酸代表疏水性有機物，以模擬天然原水之NOM，另以氯化鈣(CaCl2)提供硬度，配製成不同人工原水。接著以人工原水進行混凝瓶杯試驗，探討不同條件對有機物與濁度去除之情形，並分析所生成膠羽之顆粒平均粒徑，了解其沉澱狀況，再取適量混凝後之上澄液，以醋酸纖維材質之UF薄膜進行端點式(Dead-end)過濾，研究不同前處理條件對UF阻塞之影響。
　　實驗結果顯示，混合原水中之疏水性有機物腐植酸，較易在混凝階段被去除，藻酸的存在會嚴重影響混凝效果，增加顆粒的穩定性而造成混凝效果變差，因而需要較高混凝劑量，藉由吸附在鐵鹽所形成之氫氧化鐵顆粒上而去除。
　　薄膜過濾部分，腐植酸與藻酸會進入薄膜造成阻塞，有鈣存在的情況下，易使腐植酸、鈣與藻酸形成鍵結，造成嚴重之阻塞。前處理可影響薄膜阻塞情形。混凝劑量不足時，殘餘混凝劑進入薄膜系統造成嚴重之阻塞。在混凝劑量充足時，混凝有效地去除原水之有機物，因此後續薄膜過濾可保持較高之通量，延長薄膜濾程。經高錳酸鉀前氧化之有機物，在有鈣的情形下才易藉由架橋被混凝去除，在沒有鈣的情況下，反倒使得混凝的效果變差，進入後續薄膜系統造成更嚴重之阻塞。

Membrane fouling caused by the deposition of natural organic matter (NOM) on or within the structure of the membrane is the major limitation when using ultrafiltration to treat surface water. In this study, the effect of various pretreatment processes on hydrophobic and hydrophilic NOM removal and its impact on the following UF membrane fouling are explored.
　　Synthetic raw water, containing alginic acid (AA), humic acid (HA), calcium chloride (CaCl2) and with appropriate background ionic strength, was prepared. AA and HA were to represent hydrophilic and hydrophobic NOM, respectively, while calcium from CaCl2was to simulate the hardness ion in natural water. First, the synthetic water was coagulated by ferric chloride (FeCl3) under various dosages using jar test apparatus, with or without KMnO4 preoxidation. The water quality of both the raw water and the supernatant after coagulation were analyzed for turbidity, NPDOC and UV254. The molecular weight distribution of the dissolved organic was analyzed by high-performance size exclusion chromatography (HPSEC) with UV-VIS and online-TOC detectors. The particle size distribution of the flocculated water right after slow mixing during the jartest and also the supernatant after settling were analyzed by particle counter. Next, the supernatants from various pretreatment were filtered through bench-scale hollow-fiber cellulose acetate UF membrane unit under constant pressure.

　　The results show that ferric chloride had higher coagulation removal efficiency on HA than that of AA, probably due to the high hydrophobicity of the former. The dosage of coagulants had great impact on organic coagulation removal, and on fouling of the following UF membrane filtration. With sufficient coagulant dosage, the flux decline rate of the UF membrane reduced significantly. However, insufficient coagulant dosage even caused severer fouling than that of no pretreatment. KMnO4 preoxidation did not enhance coagulation, and may have adverse effect on permeate flux on the following UF filtration. The existence of calcium ion in the raw water caused severer fouling in UF filtration than it absence, probably due to enhanced-adsorption onto membrane surface. However, it could promote floc formation in the KMnO4 preoxidation – coagulation system, probably served as bridge between negatively charged surface, and, therefore, significantly reduced fouling on UF membrane filtration.

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