外加碳源對生物薄膜反應器處理低碳氮比高科技業廢水之影響

Abstract

隨著科技的進步，人們生活越來越便捷，然而在隱藏在絢麗的高科技產品背後，是資源的枯竭與龐大的廢棄物，其中，與人們生活息息相關的水資源，正是所有高科技業製程中不可或缺的一環。高科技產業不僅對水資源有龐大的需求，其製程中所產生的廢水更是一項重要議題。近年來台灣環保意識日漸高漲，對於高科技產業的廢水排放標準也越趨嚴峻，環保署更計畫將來將氨氮納入管制。 本研究乃探討外加碳源對薄膜生物反應器 (MBR) 處理高科技業廢水之影響。MBR 模型廠在不同 C/N (BODL/NH4+-N) 比下進行 346 天的操作，其碳氮比分別是：第 1-20 天，0.9；第 21-42 天，1.6；第 43-82 天，2.9；第 83-141 天，3.6；第 165-233 天，4.9；第 240-302 天，9.6。實驗結果顯示不論 C/N 如何變化，SS 及 BOD5 之去除效率皆達 95% 以上，而 COD 可達 80% 以上。另外，在全部實驗階段裡皆可達到完全硝化，但脫硝作用及總氮去除效率則明顯受到 C/N 比之影響。脫硝比率與總氮去除效率隨 C/N 增加而上升，在 C/N 為 9.4 時達到完全脫硝，總氮之去除效率則在 C/N 為 8.1 時達到最大值 98%。而雖然硝化作用表現良好，但實驗中發現在較低之 C/N 比時有較高之硝化速率。由即時聚合酶鏈鎖反應的結果顯示，氨氧化菌 (Ammonia oxidizing bacteria, AOB) 佔活性污泥微生物的比例在低C/N 比 (0.9) 時為高 C/N 比 (9.6) 之 10 倍，推測較高的 C/N 比因對異營菌較有利，進而影響了硝化菌在污泥中所佔的比例。脫硝菌在不同 C/N 比下則無明顯變化。另外發現污泥中之硝化菌 (Nitrite oxidizing bacteria, NOB) 以 Nitrospira 為主要菌種。

Along with the technical progress, the people live are getting more and more convenient, however, behind the gorgeous high tech product there is depletion of resources and huge waste. The water resource, which people are closely linked, is indispensable for the producing processes of high-technology industry. The high-technology industry not only has the huge requirement to the water resources, the wastewater produced from producing processes is an important topic. In recent years, with the environmental consciousness upward in Taiwan, the wastewater emission standard of high-technology industry is sterner, and the ammonia nitrogen in the wastewater will be limited in the future. The effect of supplementary carbon addition for the treatment of high-technology industrial wastewater in a membrane bioreactor (MBR) was investigated. The MBR was operated for 346 days under different C/N (BODL/ NH4- -N) ratios, i.e. 0.9, ~ 1 to 20 days; 1.6, ~ 21 to 42 days; 2.8, ~ 43 to 82 days; 3.6, ~ 83 to 141 days; 4.9, ~ 165 to 233 days and 9.6, ~ 240 to 346 days. Irrespective of the C/N ratios investigated, SS and BOD5 removal efficiencies were above 95%. Also, above 80% COD removal efficiency was observed in the entire C/N ratio investigated. In addition, complete nitrification was observed throughout the investigation. However, denitrification and total nitrogen removal efficiencies reached their maximum values at the highest C/N ratio i.e. 9.6 investigated. Real-time PCR analysis revealed 10 times higher ammonia oxidizing bacteria to total bacteria ratio under the highest C/N ratio condition (9.6) compared to the low C/N ratio condition (0.9). In addition, Nitrospira is the main nitrite oxidizing bacteria (NOB).