Development of Sterilization Strategy for Thermoduric Bacterial Spores in Photoreaction System with Solar Source

在采用半导体光催化剂的光催化杀菌体系中，发现TiO_2颗粒可以有效地杀菌微生物。在本研究中，使用了不同类型的微生物，即酿酒杆菌（细胞）、大肠杆菌（细胞）和嗜脂热杆菌（孢子）。在TiO_2悬浮或固定化体系中对这些微生物进行了灭菌，得到了以下结果：在高压汞灯（波长范围：365-579nm）照射下，为了获得孢子/细胞的有效失活率，TiO_2颗粒和溶解氧的存在是必要的。随着反应器内平均光强的增加，孢子的失活率提高。此外，溶解氧被认为提供了氧化自由基的形成，氧化自由基随后攻击孢子/细胞。孢子/细胞的失活动力学可以用ap…More适用于TiO_2粒子光激发产生的细胞浓度和氧化自由基的二阶反应速率方程来描述。此外，光照强度对孢子/细胞失活率的影响基于单命中多目标模型或系列事件模型进行了定量表达。为实现连续杀菌，将TiO_2颗粒固定在玻璃板表面，进行了大肠杆菌光催化杀菌实验。结果表明，TiO_2固定化体系的灭菌效率是相同的，并且基于序列事件模型的动力学分析得到的参数值在TiO_2悬浮体系和固定化体系中是相同的。在TiO_2悬浮体系和固定化体系中，表观失活速率常数与光强呈线性关系。表观失活速率常数与TiO_2浓度或固定化量有关，均存在最大值。综上所述，采用半导体光催化剂进行光化学灭菌对多种微生物均有较好的效果。对TiO_2固定化体系中微生物的连续灭菌操作有了基本的认识。少

In the photocatalytic sterilization system using the semiconductive photocatalysts, it was found that the effective sterilization of microbes could be obtained with TiO_2 particles. In this study, different types of microbes namely, S.cerevisiae (cells) , E.coli (cells) and B.stearothermophilus (spores) were used. The sterilization of these microbes were performed in either the TiO_2 suspended or immobilized system and the following findings were obtained :1.The presence of TiO_2 particles and dissolved oxygen was necessary in order to obtain the effective deactivation rate of spores/cells in a system illuminated with a high pressure Hg lamp (wavelengthrange : 365-579nm) .2.Spore deactivation rates were promoted with the increase in the average light intensities inside the photoreactor. In addition, the dissolved oxygen was presumed to provide the formation of oxidative radicals which subsequently attacked the spores/cells.3.The spore/cell deactivation kinetics could be described by ap … More plying the second-order reaction rate equation with respect to the concentrations of cells and oxidative radicals generated by light excitation of TiO_2 particles. Further, the effect of light intensity on spore/cell deactivation rates was expressed quantitatively based on a single-hit multitarget model or a series-event model.4.To achieve the continuous sterilization, TiO_2 particles were immobilized on a glass plate surface and the photocatalytic sterilization experiment of E.coli was performed. It was then found that the effective rate of sterilization was obtained even with the TiO_2 immobilized system, and that the values of parameteres obtained from the kinetic analyzes based on a series-event model were identical in both the TiO_2 suspended and immobilized systems.5.A linear relation was obtained between the apparent deactivation rate constant and light intensity in both the TiO_2 suspended and immobilized systems. It was also found that there existed a maximum value for the apparent deactivation rate constant with respect to TiO_2 concentration or its amount immobilized.In conclusion, photochemical sterilization with semiconductive photocatalysts was effective for various types of microbes. A basic knowledge on the continuous operation of microbe sterilization could be obtained in the TiO_2 immobilized system. Less