不同材質反應槽對高級氧化廢水處理效能之研究

Abstract

水在我們的日常生活和經濟發展中扮演著至關重要的角色。隨著極端天氣事件越來越頻繁，人們對水資源的重要性有了更深的認識，並開始意識到廢水回收再利用的潛力。因此，確保廢水處理過程中的水質符合再利用要求成為水資源管理的一個主要問題。消毒劑與水中的天然有機物反應會產生消毒副產物，而這些消毒副產物被懷疑對健康有潛在的不良影響。高級氧化處理可以有效去除水中各種形式的雜質，利用羥基自由基降解水中的各種污染物。雖然紫外發光二極體比傳統的鹵素紫外線燈更環保，但發光二極體的能量轉換效率仍然較低。然而相比於鹵素燈，發光二極體在紫外線反應槽中可以實現更均勻的紫外線劑量分佈。 本研究使用台灣污水廠加氯前的放流水作為水樣，選用波長275奈米的紫外發光二極體進行研究，目的是探討最合適的反應槽材質，以最大限度地利用紫外線能量來降解前驅物質和消毒副產物。殺菌實驗結果顯示，石英材質達到99.9%的殺菌效果最快(k值為-0.4918)，其次是不銹鋼(-0.1696)和玻璃(-0.0991)。水中餘氯的消耗和氧化效率也表明石英材質最佳(k值為-1.7948和-1.4547)，其次是內部包覆鋁箔紙的玻璃反應槽(分別為亮面-1.0142、-0.8329及霧面-1.0275、-0.7566)、不銹鋼(-0.8724、-0.8638)和玻璃(-0.4246、-0.4993)。在數分鐘內的反應試驗中，石英顯示出最出色的表現。而長達1小時的高級氧化處理實驗中添加氯的紫外發光二極體顯示，不銹鋼和包覆鋁箔紙的玻璃反應槽在降解前驅物質和消毒副產物方面效果良好，整體效果優於其他材質的反應槽。從螢光激發/發散陣列圖觀察到，包覆霧面鋁箔紙的玻璃反應槽的降解效果明顯優於包覆亮面鋁箔紙的反應槽。綜合以上結果，本研究建議選擇不銹鋼作為反應槽的材質。儘管不銹鋼在殺菌實驗中並非表現最佳，但在3分鐘內即可達到滅菌效果，且在前驅物質和消毒副產物的降解處理方面具有顯著效果。此外，考慮到台灣多數污水處理廠使用不銹鋼槽體材質，因此在未來的實際應用中，選擇不銹鋼是較為合適的選擇。

Water is an essential resource that plays a crucial role in our daily lives and economic growth. With the increasing frequency of extreme weather events, there is a growing recognition of the importance of water resources and the potential for recycling and reusing wastewater. Consequently, ensuring that the water quality in the wastewater treatment process meets the standards for safe reuse has become a significant concern in water resource management. One challenge in water treatment arises from the reactions between disinfectants and natural organic matter in water, which can generate disinfection by-products (DBPs). These by-products are suspected of having adverse health effects. However, advanced oxidation processes (AOPs) have been proven effective in eliminating various types of impurities. By utilizing hydroxyl radicals, AOPs can degrade a wide range of contaminants present in water. While traditional halogen UV lamps have been commonly used in water treatment, ultraviolet light-emitting diode (UV LED) offer a more environmentally friendly alternative. Although UV LEDs have lower energy conversion efficiency compared to halogen lamps, they provide a more uniform distribution of UV energy in the reactor. In this study, water samples collected from a sewage treatment plant in Taipei, Taiwan before chlorination was used to assess suitable of using UV LED as UV source in UV/chlorine process. A UV LED with a wavelength of 275 nm was selected to investigate the most suitable material for reactors. The objective of this study was to maximize the utilization of UV energy for degrading DBP precursors and DBPs. The results of the sterilization experiment demonstrated that quartz material (k=-0.4918) exhibited the fastest sterilization effect to achieve a 99.9% reduction in microorganisms. Stainless steel (k=-0.1696) and glass (k=-0.0991) followed quartz in terms of sterilization efficiency. Additionally, the consumption and oxidation efficiencies of residual chlorine in water indicated that quartz material (k=-1.7948, -1.4547) performed the best, followed by a glass reactor cladded with aluminum foil (k in glossy=-1.0142, -0.8329 and in matte=-1.0275, -0.7566), stainless steel (k=-0.8724, -0.8638), and glass (k=-0.4246, -0.4993). In experiments conducted within minutes, quartz demonstrated the best performance. When chlorine-added UV LEDs were used in an hour of UV/chlorine treatment, stainless steel and glass reactor cladded with aluminum foil proved their effectiveness in degrading precursor substances and DBPs, outperforming other reactors. Furthermore, the fluorescence excitation−emission matrix (FEEM) spectrum revealed that the glass reactor cladded with matte aluminum foil exhibited a significantly better degradation effect than the reactor cladded with glossy aluminum foil. Based on the overall results, the study suggests that stainless steel should be chosen as the material for the reactor for UV photolysis. Although stainless steel did not exhibit the highest sterilization efficiency, it achieved the desired sterilization effect within 3 minutes of reaction time and significantly contributed to the degradation of precursor substances and DBPs. Additionally, stainless steel is recommended for future practical AOP applications and is a sensible choice.