近年來，對環保意識抬頭之下，我們開始重視空氣品質，由於平均每人每日約有80～90%的時間待在室內環境，因此室內空氣品質尤其重要，現階段已開發許多控制及消毒生物氣膠的方法進而提升室內空氣品質，例如熱能、紫外線照射、光觸媒、空氣過濾器等，但有些方法需消耗大量能量，有些則對人體有害。本研究利用目前在水處理及生物消毒領域廣泛應用的綠色化合物──高鐵酸鉀做為消毒劑，並以水中常見細菌──大腸桿菌Escherichia coli為參考，空氣中採集的細菌──Micrococcus sp.、Staphylococcus kloosii及特定致病菌金黃色葡萄球菌Staphylococcus aureus做為失活目標，進而探討高鐵酸鉀對於不同菌種間的失活效果。本研究使用不同濃度的高鐵酸鉀溶液與菌液混和，並於每個取樣點將菌樣取出，以環保署公告之水中總菌落數檢測方法－塗抹法（NIEA E203.56B）進行菌落數計算，最後以每個取樣點菌落數與初始菌落數差及初始菌落數比值得到失活率。使用濃度為3 mg/L的高鐵酸鉀時，E.coli的失活率可在反應時間五分鐘達到100%，當提高濃度至5 mg/L時則可以在三分鐘達到相同效果。對於Micrococcus sp.及S. kloosii而言，高鐵酸鉀也可在五分鐘使其失活，但需要較高的濃度100 mg/L及200 mg/L。對於致病菌S. aureus，使用濃度為500 mg/L的高鐵酸鉀在五分鐘僅得到90.82%的失活率，將反應時間拉長至30分鐘才得以使其100%失活，研究結果也顯示，假使高鐵酸鉀濃度太低，縱使將反應時間拉長也達不到100%失活率。同時也將三種純度不同（15%、73%、90%）且濃度為5 mg/L的高鐵酸鉀進行對大腸桿菌失活效果的實驗比較其間差異，在前半分鐘純度90%的高鐵酸鉀僅達到51.28%失活率，而其他二者皆達到65%失活率，但在第2.5分鐘即達到100%失活率，而純度15%及73%也在第三分鐘達到100%失活率，結果顯示，純度高低並不會對高鐵酸鉀的失活效果造成太大的影響。高鐵酸鉀不僅可以使水中常見的大腸桿菌100%失活，也可使從空氣中採集之非致病性細菌及特定的致病性細菌失活，高鐵酸鉀亦可以在更高濃度及更長的反應時間下作用，達到100%失活效果。與其他常見控制及消毒生物氣膠的方法相比，使用高鐵酸鉀不會像使用熱處理一樣需要大量耗能，也與使用紫外線照射不同，副產物是無毒的，不需要添加其他產物即有良好的失活效果，為一良好的消毒劑。 The quality of indoor air has drawn increasingly more attention because of its impact on the well-being of people who are exposed to the indoor contaminants. The presence of airborne and surface-bound bacteria is one of the primary concerns of indoor air quality. Various methods such as ultraviolet irradiation and chlorination have been commonly applied to inactivate bacteria. These methods, however, may be harmful to the health of the people and the environment. This study examines the effectiveness of applying hexavalent ferrate, a powerful and environmentally benign oxidant, for the inactivation of several types of bacteria, including Escherichia coli, locally collected airborne bacteria identified as Micrococcus sp. and Staphylococcus kloosii, and a known pathogen in Staphylococcus aureus. All bacterial inactivation experiments were performed by mixing a pre-determined range of ferrate dosage with the bacteria inoculated in liquid Luria-Bertaini broths under room temperature. The reactants at the various dilution levels were then transferred to agar plates for inoculation to determine the growth of tested bacteria. The applied potassium ferrate had a purity of 15% experimentally determined. Statistically, E. coli was completely inactivated within 5 minutes when a ferrate dosage of 3 mg/L was applied, and within 3 minutes when 5 mg/L was applied. Applying ferrate with higher purity (73% and 90%) did not result in significantly different inactivated rate. In all cases, a reaction time of 3 minutes was needed to completely inactivate E. coli. The two airborne bacteria Micrococcus sp. and S. kloosii were completely inactivated in 5 minutes with a ferrate dosage of 100 mg/L and 200 mg/L, respectively. In comparison, a higher ferrate dosage (500 mg/L) and longer reaction time (30 min) were needed to completely inactivate S. aureus. No complete inactivation of S. aureus was observed when the applied ferrate dosage was less than 500 mg/L, demonstrating the higher resistance of S. aureus to ferrate.
