一般淨水場會在混沉程序前添加次氯酸鈉等前氧化劑，來減弱藻類活性或改變藻體表面性質，以提高後續混沉效果。加氯對藻類的去除率和產生溶解性有機物有高相關性，加氯同時會產生三鹵甲烷等有害健康物質。此外，因台灣地小人稠，近年來因大多的掩埋場已飽和且處理污泥之費用年年增高，大量的廢棄淨水污泥採用掩埋方式並不是良好之處置方法，若能有效利用此類廢棄污泥，必定能節省下大筆的清運以及處理費用。本研究係利用對淨水污泥轉製之鐵錳氧化磁體，做為除藻之添加劑，既能將淨水廠所需多支付之處理污泥之費用降低，也能達到將廢棄物有效回收再利用之目的。本研究以特定藻類數量水樣，進行前氧化搭配混凝程序實驗，另以不同混凝劑(聚氯化鋁，氯化鐵)搭配淨水污泥再利用之鐵錳氧化磁性顆粒，比較其混沉除濁及除藻的效能。結果顯示，以聚氯化鋁(PACl)搭配鐵錳磁性顆粒除藻效率可達97.4%最佳；聚氯化鋁(PACl)搭配NaOCl除藻效率91.0%次之，但有藻體被破壞，胞外物釋出的情形發生；單獨使用磁性顆粒除藻效果效果僅68.4%最差。回收再生的鐵錳磁性顆粒混沉除藻效率，反而比原來尚未進行除藻的新鮮鐵錳磁性顆粒除藻效果佳。鐵錳磁性顆粒的回收率，無論有無混凝劑(PACl)的搭配使用，均有95%以上穩定的回收率表現。 In Taiwan, the water treatment plant (WTP) will add pre-oxidizing chemical (such as NaOCl) before coagulation/sedimentation to alter the activity or surface properties of algae to improve the algae removal efficiency. However, addition of chlorine type disinfectant will produce harmful byproducts, e.g trihalomethanes (THMs).On the other hand, most of the landfills in Taiwan are saturated and the treatment cost of WTP sludge is getting higher in recent years. Hence the recycle of large amount of WTP sludge will save a lot of clearance cost. In this study, considering best of both worlds, the WTP sludge was converted to “Iron and Manganese Oxide Magnets (IMOM)” and used as adsorbent for the algae removal. Not only the sludge treatment cost will largely decrease but also the goal of waste recycle can be achieved.In this work, synthetic water sample with specific amount of algae was prepared befor implementing the oxidation and coagulation experiments. Then PACl or FeCl3 was added respectively with IMOM to evaluate the turbidity and algae removal efficacy. The results show that removal rate of algae treated with PACl and IMOM is 97.4%, whilst that of PACl and NaOCl is 91.0%. Using IMOM instead of NaOCl improve the algae removal. Moreover, addition of NaOCl will disintegrate algae and release extracellular material. As for removing algae by adding IMOM alone, the rate is just 68.4%. Recovery of spent IMOM was also evaluated. The recovery rates of spent IMOM are both higher than 95% for adding IMOM and PACl simultaneously and adding IMOM alone. Furthermore, the spent IMOM shows higher algae removal rate than the fresh IMOM.
