Experimental Study Of Non-Thermal Plasma Sterilization

The non-thermal plasma antiseptic technology is a new environmental protection technology which has developed in recent 20 years. Research shows that plasma sterilization technology can overcome limitation and deficiency of the traditional method. It has the potential to offer normal temperature generating sterilize, will not burn out the treated goods, will not produce the by-product and toxic residue. It has the advantage of high efficiency and no pollution, so it becomes a research hot focus in the world. In general, the plasma research for gas sterilization is relatively more, but the disinfection of water seriously lacks research. This paper gets to the experimental study of this new technology bactericidal properties.There is a variety of discharging forms and many methods of generating non-thermal plasma,the temperature of corona discharge plasma is low, and the corona discharge plasma could be produced at normal temperature and atmospheric pressure. Therefore, this subject designs and sets up a set of equipment of corona discharge plasma, uses the high voltage DC power supply electric to strike through gases, generates non-thermal plasma to kill germs in the water.This thesis researches for the characters of corona discharge plasma, including the theories of corona discharge, the condition of corona discharge production,the process of corona discharge, and the mechanisms of corona discharge. The subject chooses Escherichia coli 285 as experimental bacterial, researches for the results of sterilization by non-thermal plasma under the static experimental condition, and inspects the sterilization effect of different factors, such as voltage, conductance, electrodes distance, water level, electrode forms and different air medium to the sterilization with non-thermal plasma. Meanwhile, it sets up experimental system, conducts the dynamic experiment to compare the different results of the static and dynamic experiment and probe into the mechanism of sterilization.Results shows that under the static experiment condition, the non-thermal plasma has the effect of sterilization for the E.coli. The effect of the sterilization increases with the increases of the voltage and treatment time, while it decreases with the increases of the electrodes distance and the water level. Changes in the conductance of the water have nothing to with the effect of sterilization. In addition, the paper researches the effects of different air medium on the sterilization, and the results shows that the sterilization effect of argon plasma is better than nitrogen plasma better than air plasma.Moreover in the dynamic experiment, this thesis studies the effect of the sterilization on the E. coli of the non-thermal plasma in the flow regime which are treated by two circulating methods include: going once through the processor and circulating the processor in the whole system. The result shows the capability of the non-thermal plasma is direct ratio with the voltage and the treatment time. The sterilization effect is very obvious, and the effect of the sterilization increases with the increases of the flow of water.