錳砂活化條件對抗菌能力之影響

Abstract

一般淨水場之過濾程序中常使用石英砂作為濾料，其表面組成以不具活性的SiO2為主，經長時間過濾操作後，石英砂濾床容易聚集微生物並形成生物膜於濾砂表面，進而導致濾床堵塞影響過濾效率。因此，為了延遲微生物於濾床上之生長，需進一步開發適合應用於大型淨水場之濾料，已知含有MnO2之錳砂目前已廣泛應用於去除水中之鐵錳，但其抗菌能力仍需進一步探討。 本研究目的為利用不同pH及高錳酸鉀濃度作為條件活化錳砂以探討其抗菌效能之差異。抗菌性研究以E.coli菌液及LB(Luria-Bertani)培養液作為試驗水樣，在24小時、37℃、及150 rpm恆溫震盪培養，以SYTO 9/PI搭配流式細胞儀分析每一個採樣時間點懸浮液中總菌數及細胞活性比例；並利用掃描式電子顯微鏡搭配能量散射光譜儀(SEM/EDS)及X射線電子能譜儀(XPS)分析活化錳砂表面錳含量及錳氧化物形成比例。 研究結果顯示，提高pH對錳砂之抗菌效能明顯增加，且經pH 11.5活化處理之錳砂抗菌能力最佳；當KMnO4濃度越高時，活化錳砂之抗菌能力越顯著，而以MnO2為主之錳氧化物含量為主要影響抗菌能力之原因。 關鍵字：錳砂、抗菌能力、過濾、錳氧化物

Quartz sand with silicate oxide is commonly used as filtration media in filtration processes in water treatment plant (WTPs). After long time operation, quartz sand is easily attached by microorganism during filtration, and the severe filter clogging by a large amount of biofilms forms quickly. In water treatment, manganese sand with MnO2 media has been widely adapted as a filter media to remove heavy metal from water, but its antibacterial ability still needs to be examined. In this study, the different pH and concentrations of potassium permanganate was carried out to activate manganese sand for the comparison of the antibacterial ability. The lab-prepared water containing E.coli by Luria-Bertain (LB) medium was used for batch cultivation. For cultivation test, the total E.coli cells and membrane-damage cells in the suspension were determined by Flow cytometry (FCM) coupled with SYTO 9/PI staining method after 24 h of cultivation at 37℃ and 150 rpm. Activated manganese was analyzed by scanning electron microscope (SEM/EDS) and X-ray photoelectron spectroscope (XPS) to measure the manganese content and the manganese oxide proportion on the surface of manganese sands. The results have showed that the antibacterial ability of manganese sands increased significantly with the raise of pH and thereafter reached the optimum performance at the pH 11.5. Furthermore, the higher concentration of KMnO4 to activate manganese sands resulted in the stronger antibacterial ability of the activated sands. This is as a result of the predominance of MnO2 on the surface of activated manganese sand. Keyword: manganese sand, antibacterial ability, filtration, manganese oxide