|摘要: ||由於生活型態改變，國人處於室內環境中之時間比率高達80~90%，經由室內空氣接觸生物性危害之機會也隨之增加。本研究之目的為使用非熱介電質放電(Dielectric Barrier Discharge, DBD)系統產生之高濃度臭氧及結合觸媒分解臭氧尾氣來淨化室內生物氣膠，以瞭解不同操作條件對臭氧殺菌效力之影響、觸媒分解臭氧效力、釐清DBD電漿中臭氧殺菌之貢獻及評估臭氧殺菌結合觸媒系統應用於淨化室內空氣中生物性危害之可行性。
Most people spend eighty to ninety percent of their time in indoor envi-ronment due to lifestyle changes in Taiwan. The probabilities to expose to bio-hazards threat through indoor air are increasing. The objective of this study was to disinfect indoor bioaerosols by using the hybrid system of high concentration ozone generated by non-thermal dielectric barrier discharge (DBD) system, and ozone decomposition by catalyst. There were many research results had been explored in this study including the influence of various experimental conditions on germicidal effects of ozone, the decomposed abilities of ozone by catalysts, the contributions of ozone toward disinfection in DBD plasma system, and the feasibility of purified indoor biohazards by the hybrid system of ozone and cat-alyst.
The first part of experiment was the bioaerosol disinfection in laboratory chamber. Four kinds of bioaerosols (E. coli, B. subtilis, C. famata and P. citri-num) with concentrations of 106CFU/m3 were generated by Collison three-jet nebulizer. The germicidal effects to bioaerosols of ozone were measured at ozone concentration of 0~175ppm, relative humidity of 30~70%, and exposed time of 1~10sec. The decomposed efficiency of ozone in tail gas after disinfec-tion, MnO2/AuO and MnO2/AC as catalysts, was detected by ozone monitor. The second part of experiment related to evaluating the controlled efficiency of total bacterial and fungal bioaerosols which were applied practically in small of-fice. Then, the research also focus on evaluating the germicidal efficacy of ozone to bioaerosols at two different air change rates (air changes per hour, ACH=0.45/hr and 3.89/hr).
The results indicated that the needed concentrations of ozone to reach dis-infection efficacy of 90% (at relative humidity of 70% and expose time of 10sec) for Escherichia coli, Candida famata var. flareri and Penicillium citrinum spore bioaerosols were 50, 100 and 150ppm respectively. However, it was ineffective to Bacillus subtilis endospore bioaerosols even at high concentration of 175ppm ozone under the same relative humidity and exposure time. As MnO2/AuO and MnO2/AC catalysts, and at gas hourly space velocity (GHSV) of 1.03�104h-1, the concentration of 175ppm ozone in tail gas was decomposed to under detect-able range.
The orders of germicidal efficacy of ozone to bioaersols were Escherichia coli > Candida famata var. flareri > Penicillium citrinum spore > Bacillus sub-tilis endospore. Increasing of relative humidity and exposure time could enhance the germicidal efficacy of ozone to the three bioaerosols but no efficacy to Ba-
cillus subtilis endospore bioaerosols. Compared the results with literature in this study, ozone has higher contribution to disinfect the vegetative cell type of bio-aerosols but lower contribution to hard spore type of bioaerosols within the dis-infection mechanisms in DBD plasma system. The concentrations of indoor bioaerosols (total bacteria and fungi) and ozone in tail gas were reduced to be-low 50 CFU/m3 after 2 hours lasting treatment of using the hybrid system of ozone and catalyst in small office. The ventilation rate had no significant effect on germicidal efficacy in indoor environment. The annual cost was economical by using the hybrid system of ozone disinfection and catalyst to purify indoor air.
Summary, the germicidal efficacies of ozone to three types of bioaerosols (two vegetative cells and one spore) were above 90%. Ozone also had good dis-infection efficiency after hours treatment applied in small office. In addition, catalyst could completely decompose residual ozone in tail gas. Therefore, the hybrid system of ozone disinfection and catalyst not only had high germicidal efficacy and low cost but also can protect people indoor from exposing to ozone directly. Preliminary assessment of this study had showed that ozone combined with catalyst was a feasible method to control indoor biohazards and improve indoor air quality.