Air and Water Sterilization using Non-Thermal Plasma (original) (raw)
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Plasma for air and water sterilization
2008
This chapter describes the research efforts of Drexel Plasma Institute (DPl) in the area of plasma-based air and water sterilization. Motivation of this research is presented as well as the methods for selection of parameters for the experimental systems. Experimentally obtained results for air sterilization demonstrate that the direct influence of plasma charged particles on airborne bacteria in combination with active chemical substances generated by plasma is the probable reason for high sterilization efficiency of the Dielectric Barrier Grating Discharge (DBGD). Energy input on the level of 13 kJ/m3 is enough to reach a 5-log reduction of viable E. coli bacteria. Experimentally reached D-value (the dosage required for a 90Yo reduction of the number of viable microorganisms) for E. coli bacteria deactivation in water using spark discharge is very low, about 125 kJlm3, and UV-radiation is the most plausible sterilization factor in this case. A new seminumerical model is proposed for initial phase of electrical breakdown in water.
Water sterilization using plasma corona discharge
INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019
Plasma corona discharge is used for water sterilization. In this study, plasma corona discharge was generated through a pair of stainless steel electrodes connected to an AC high voltage of 6.52 kV. The distance between electrodes is ± 1.5 cm. Variations in treatment time were 0, 60 and 90 minutes. Total Plate Count (TPC) using the pour plate method is used to calculate the qualitative results of the number of microorganisms. The results show that the longer the treatment time, the fewer microorganisms contained in water. At 0 minute treatment containing microorganisms 2.5 x 10 7 TPC / ml, 60 minutes containing microorganisms 3.0 x 10 7 TPC / ml and at 90 minutes 1.2 x 10 7 TPC / ml.
Evaluation of treatment and disinfection of water using cold atmospheric plasma
Journal of Water and Health, 2016
In this paper, the disinfection of water is investigated using plasma spark treatment and the results are compared with conventional techniques. Inactivation of the Enterococcus faecalis and Escherichia coli bacteria is considered in the treatment process of water by the plasma spark. For this purpose, many physical and chemical parameters of water are measured and the obtained results demonstrate a reduction of 8-log in colony forming units of E. coli and E. faecalis at 15 minutes and 12 minutes, respectively. The results of this research show that no ozone is produced during the plasma spark treatment. Moreover, inactivation of a large number of bacteria without any change of pH shows that pH is not the cause of the bacterial inactivation. It is concluded that the main causes of the inactivation of bacteria in the treated water are H2O2 molecules and the electrical fields generated by plasma.
Atmospheric-pressure, nonthermal plasma sterilization of microorganisms in liquids and on surfaces
Pure and Applied Chemistry, 2008
Gas discharge plasma inactivation of microorganisms at low (close to ambient) temperature is a promising area of investigation that is attracting widespread interest. This paper describes atmospheric-pressure, nonthermal plasma (NTP) methods for cold sterilization of liquids and thermal sensitive surfaces. These methods are based on the use of direct current (DC) gas discharge plasma sources fed with steady-state high voltage. Parameters characterizing the plasma sources used (plasma-forming gas, gas flow rate, electric power consumed, etc.) are given. The results for plasma sterilization of different microorganisms (vegetative cells, spores, fungi, biofilms) are presented. An empirical mathematical approach is developed for describing NTP inactivation of microorganisms. This approach takes into account not only the destruction of different components of the cells, but their reparation as well.
Inactivation of Escherichia coli by atmospheric pressure plasma jet in water
Journal of Water and Health
The main aim of this work is inactivation of Escherichia coli in water using a laboratory-scale radio-frequency atmospheric pressure Argon plasma jet. This bacterium is widely present in the environment, especially in drinking water, and its pathogenic effects are very harmful. For this purpose, an Argon flow rate of 3.5 slm, maximum plasma power of 200 W, and discharge frequency of 13.56 MHz was conducted to generate a uniform plasma plume for water treatment. 150 ml of drinking water contaminated by E. coli was exposed to the radiation of plasma placed about 3 cm within the water, the treatment time varied from 2 to 6 minutes at 100, 150, and 200 W of plasma input power. The temperature of the plume, discharge current and voltage, and electron density were all measured to characterize the plasma. Active species such as excited molecules, ions, and radicals produced in the plasma in water were detected using the optical emission spectroscopy method. The decreasing behavior of live ...
Applied Sciences
Various reactive oxygen and nitrogen species are accompanied by electrons, ultra-violet (UV) radiation, ions, photons, and electric fields in non-thermal atmospheric pressure plasma. Plasma technology is already used in diverse fields, such as biomedicine, dentistry, agriculture, ozone generation, chemical synthesis, surface treatment, and coating. Non-thermal atmospheric pressure plasma is also considered a promising technology in environmental pollution control. The degradation of organic and inorganic pollutants will be massively advanced by plasma-generated reactive species. Various investigations on the use of non-thermal atmospheric pressure plasma technology for organic wastewater purification have already been performed, and advancements are continuing to be made in this area. This work provides a critical review of the ongoing improvements related to the use of non-thermal plasma in wastewater control and outlines the operational principle, standards, parameters, and bounda...
Studying the non-thermal plasma jet characteristics and application on bacterial decontamination
Springer Berlin Heidelberg, 2018
Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontamination of bacteria. In this paper, we want to improve and characterize a non-thermal plasma jet to employ it in processes of sterilization. The electrical characteristics was studied to describe the discharge of the plasma jet and the development of plasma plume has been characterized as a function of helium flow rate. Optical emission spectroscopy was employed to detect the active species inside the plasma plume. The inactivation efficiency of non-thermal plasma jet was evaluated against Staphylococcus aureus bacteria by measuring the diameter of inhibition zone and the number of surviving cells. The results presented that the plasma plume temperature was lower than 34 C at a flow rate of 4 slm, which will not cause damage to living tissues. The diameter of inhibition zone is directly extended with increased exposure time. We confirmed that the inactivation mechanism was unaffected by UV irradiation. In addition, we concluded that the major reasons for the inactivation process of bacteria is because of the action of the reactive oxygen and nitrogen species which formed from ambient air, while the charged particles played a minor role in the inactivation process.
Effect of Dielectric and Liquid on Plasma Sterilization Using Dielectric Barrier Discharge Plasma
PLoS ONE, 2013
Plasma sterilization offers a faster, less toxic and versatile alternative to conventional sterilization methods. Using a relatively small, low temperature, atmospheric, dielectric barrier discharge surface plasma generator, we achieved ≥6 log reduction in concentration of vegetative bacterial and yeast cells within 4 minutes and ≥6 log reduction of Geobacillus stearothermophilus spores within 20 minutes. Plasma sterilization is influenced by a wide variety of factors. Two factors studied in this particular paper are the effect of using different dielectric substrates and the significance of the amount of liquid on the dielectric surface. Of the two dielectric substrates tested (FR4 and semi-ceramic (SC)), it is noted that the FR4 is more efficient in terms of time taken for complete inactivation. FR4 is more efficient at generating plasma as shown by the intensity of spectral peaks, amount of ozone generated, the power used and the speed of killing vegetative cells. The surface tem...
Atmospheric pressure plasma jet effects on sterilization of e. coli and s. aureus
2011 Abstracts IEEE International Conference on Plasma Science, 2011
ABSTRACT form only given. In the recent days, since the epidemic spread of diseases, sterilization has become very important. Atmospheric pressure plasma jets which are used locally and effective results for sterilization procedures are popular. In this study, we produced atmospheric pressure plasma jet with helium flow and used for sterilization of Escherichia coli and Staphylococcus aureus. In the experiments, hundred-fold diluted 250 μlt McFarland bacteria were used in eppendorf tubes for plasma treatment. The effects of plasma treatment time (1, 2, 3 second), applied voltage frequency (5-10 kHz) and amplitude (Vpp 15-16 kV) on sterilization were investigated. Plasma current-voltage characteristics and optical emission results were given.
Low pressure plasma discharges for the sterilization and decontamination of surfaces
New Journal of Physics, 2009
The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O 2 mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their deactivation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.