錳砂表面錳氧化物之存在對抗菌能力之影響

Abstract

石英砂為一般淨水場過濾程序中經常使用之濾料，但因表面以不具活性之SiO2為主要氧化物，因此當經過長期過濾操作之後，石英砂濾床表面容易被微生物所附著，進而生成生物膜蓬勃發展造成濾床嚴重堵塞。在水處理中，表面披覆著MnO2之錳砂已被廣泛應用於去除地下水之鐵、錳離子，然而，其抗菌能力仍待後續研究。 本研究之目的為比較經過不同高錳酸鉀(KMnO4)活化程序之錳砂與未經活化之錳砂及石英砂抗菌能力之差異。抗菌性試驗以E. coli菌液及含有LB(Luria-Bertani)實驗用水作為實驗材料。在48小時之37℃恆溫震盪培養試驗中，以SYTO 9/PI搭配流式細胞儀(FCM)分析每一個採樣時間懸浮液之總菌數及細菌活性比例，搭配螢光顯微鏡(EFM)得出細胞膜受損細菌之影像，最後以掃描式電子顯微鏡(SEM)觀察菌體表面形貌。實驗室規模之管柱過濾試驗則是比較石英砂及活化錳砂管柱去除細菌之能力及出流水之細菌剩餘活性。 結果指出，錳砂之抗菌能力優於石英砂，且經過活化程序可提升其抗菌能力。其中，經鹼性活化程序可使錳砂表面具有較高含量之活性MnO2，因此經過pH10活化程序之錳砂其抗菌能力優於經過pH7活化程序之錳砂；管柱過濾試驗中兩種活化錳砂之除菌效能均優於石英砂，且活化錳砂過濾對菌體之破壞程度較石英砂過濾高，因此其過濾出流水細菌之活性遠低於石英砂過濾出流水細菌之活性。

Quartz sand with silicate oxides is commonly used as filtration media in filtration process in WTP. It is easily attached by microorganism during filtration and the severe filter clogging induced 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 the Fe and Mn ions from water for groundwater treatment plant, but its antibacterial ability is under investigation. The goal of this study is to investigate the antibacterial ability of commercial manganese sand with KMnO4 activation in different pH compare with the antibacterial ability of manganese sand and quartz sand. The lab-prepared E. coli–containing water with nutrition source (Luria-Bertani, LB) was used as a culture media. For cultivation test, the count of E. coli in the suspension during 48 hr cultivation at 37℃ were counted by Flow cytometry (FCM) at various cultivation time, and epifluoresence microscopy (EFM) coupled with SYTO9/PI staining method was used to image membrane-damaged cells of each sample. Finally, the morphology of E. coli was observed by Scanning electron microscope (SEM). The lab-scale column filtration test with quartz sand and activated Mn sand was conducted simultaneously to evaluate the efficiency of E. coli removal and the viability of residual E. coli in the filtrate. The results have showed that the antibacterial ability of manganese sand is superior to that of quartz sand. It would enhance the antibacterial ability as manganese sand undergoes KMnO4 activation. The ability to inhibit bacterial growth for manganese sand with KMnO4 activation at pH10 are superior to manganese sand KMnO4 activation at pH7 due to the increased active MnO2 particles. For column filtration test, the efficiency of E. coli removal of manganese sand with pH7 and pH10 activation is superior to that quartz sand. The breakage of E. coli through the filtration of activated Mn sand is higher than that through filtration of Quartz sand. Thus, the viability of E. coli in the effluent from the column of manganese sand with pH7 and pH10 activation is less than that from quartz sand column.