JP2005515843A6 - Sterilization and decontamination system using plasma discharge and filter - Google Patents

Abstract

  A sterilization / decontamination system in which a non-thermal plasma discharge device is placed upstream of a suspension medium (filter, electrostatic precipitator, carbon bed, etc.). The plasma discharge device generates plasma, and the plasma is emitted through an aperture (capillary, slit, etc.) of the first dielectric. Plasma-generated sterilizing active species can inactivate or reduce such substances contained in contaminated fluid streams and / or on objects when exposed to contaminants and undesirable particulate matter. Thus, undesirable contaminants in the fluid to be treated are first reduced while being exposed to plasma-generated sterilizing active species in the plasma region of the discharge device. In addition, the plasma-generated sterilizing active species is carried to the downstream suspension medium and deactivates contaminants collected on the suspension medium itself when in contact with the medium. The suspension medium can advantageously be cleaned in situ. In order to further increase the sterilization efficiency, additive gas / free gas / carrier gas (alcohol, water, dry air, etc.) may be injected into the aperture provided in the first dielectric. These additives reduce byproduct undesired ozone pollutants that are produced and increase the concentration of the plasma-generated disinfectant activator. Downstream of the filter, the fluid stream can be further processed by exposing it to a catalyst medium or additional suspension medium to further reduce the amount of undesirable particulate matter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application, (a) a continuation-in-part application of U.S. patent application Ser. No. 09 / 738,923 of December 15, 2000 filed, of the U.S. patent application December 15, 1999 filed No. 60 / 171,198 and US Patent Application No. 60 / 171,324 filed on Dec. 21, 1999. This application also claims to benefit from (b) US provisional application 60 / 336,866 filed on November 2, 2001 and 60 / 336,868 filed November 2, 2001. To do. All of these applications are hereby incorporated by reference as part of the present specification.

TECHNICAL FIELD The present invention relates to methods and systems for air flow sterilization and object / surface decontamination, and more particularly to such methods and systems using non-thermal plasma discharge devices and non-thermal plasma generators.

  Suspension media (filters, carbon beds, electrostatic precipitators, etc.) used in ventilation air treatment devices collect various contaminants in the air. Examples of such substances include, but are not limited to, spores, viruses, biological substances, particulate substances, and bacteria. Over a period of use of the suspension medium, undesired contaminants are captured and collected, reducing the performance of the medium and condensing biological hazards, and providing a source of biological hazards to the ventilation system. turn into. Until now, there are two types of conventional methods that have been used to remove contaminants from suspension media. That is, a method of replacing the suspension medium and a method of periodically removing contaminants from the suspension medium in situ. In any of these conventional methods for disposing of pollutants, it is likely that some of the captured spores, pathogens and other undesirable particulate matter will be released into the atmosphere. Also, if a suspension medium containing undesirable particulate matter is replaced, the contaminated suspension medium must be disposed of properly. This is especially important in hazardous locations such as hospitals, laboratories and operating rooms that are exposed to very dangerous pathogens (tuberculosis, smallpox, anthrax, etc.) and other contaminants. In such places, if pathogens etc. are released from the ventilation system, even very low concentrations can have very detrimental effects on health.

  It would be desirable to develop an apparatus and method for decontaminating suspension media in situ that can eliminate or substantially reduce the release of contaminants to the ventilation system.

  The process and system for sterilization and decontamination according to the present invention has biological activity but is compared as a by-product generated during non-thermal plasma generation (preferably in the presence of organic matter and oxygen). By using a sterilized species having a short life span, the sterilization efficiency is improved while reducing dangerous substances on health or environment.

  In particular, the present invention relates to a method for decontamination of objects such as suspension media, food, ventilation ducts, medical devices, and fluid sterilization. As a byproduct of the non-thermal plasma-chemical reaction, active, relatively short-lived (eg, milliseconds or seconds) bactericidal active species are produced. Since the lifetime of this sterilizing active species is relatively short, its sterilizing ability is highest when it is in the vicinity of the non-thermal plasma discharge device. At the same time, due to the short lifetime, this bactericidal active species quickly degrades into harmless benign by-products. This degradation characteristic is particularly useful in situations where sterilization must be achieved with minimal health or environmental hazards. To further increase sterilization efficiency, additive fluids / carrier fluids / free fluids such as various organic compounds (usually air) can be injected into the plasma discharge device through the electrodes (or directly). Introducing additive fluid / carrier fluid / free liquid into the plasma discharge device increases the production of bactericidal active species carried with the fluid stream. In this way, the sterilizing active species can be sent to specific areas or areas of objects to be sterilized or decontaminated as desired.

  For example, when processing air, an air filter is arrange | positioned downstream of a non-thermal plasma discharge apparatus. The contaminated air to be treated first passes through the non-thermal plasma discharge device and then passes through the filter. Some of the spores and bacteria have already been deactivated upstream of the filter by directly interacting with the bactericidal active species generated by the non-thermal plasma discharge device, but some of them are trapped on the filter. is there. In order to inactivate a significant, if not complete, pathogen captured on the downstream filter, the filter can be exposed continuously or periodically to the upstream bactericidal active species. At the same time, the germicidal active species decompose in the filter or downstream of the filter so that the air that is exhausted from the filter, i.e. passes through the filter and enters the room, contains no or even a small amount of germicide. Additional filtration media or catalyst media (such as an ozone catalyst) may be added downstream to further remove residual traces of undesirable contaminants and / or by-products from the air stream.

  Circulating the carrier gas (usually air) is advantageous because it can efficiently transport the bactericidal active species to the desired contaminated area or portion of the suspension medium to be treated. As soon as the supply of power to the plasma discharge device is stopped, the production of germicidal active species stops and the object must be removed from the chamber immediately without delay.

  In a preferred embodiment, the plasma generation system is a dielectric capillary type or a dielectric slit type, and a non-thermal plasma gas discharge to ambient air or other gas by applying a high RF, DC or AC voltage to the electrode. Can be performed. Plasma-chemical reaction by-products (ozone, nitrogen oxides, organic acids, aldehydes, etc.) that are always present in trace amounts in the afterglow of the discharge are typically used to remove these by-products from the air Captured in an off-gas treatment system utilizing catalysts, other methods.

By using ethanol / air or other organic vapor / air mixtures as additive fluid / carrier fluid / free fluid sent through electrodes to the discharge zone, alkyl groups of hydrogen atoms in bacterial DNA (C _n H _The substitution by _{2n + 1} ) is promoted and more bactericidal active species that inactivate pathogens can be generated. Alkylation is thought to be one of the mechanisms by which ethylene oxide (a well-known fungicide) inactivates pathogens. Perhaps alkylation is the main mechanism of sterilization in oxygen / organic plasma afterglow.

  One embodiment of the present invention relates to a sterilization and decontamination system including a plasma discharge device, preferably a non-thermal plasma discharge device, the device having a first dielectric, the first dielectric being a plasma. Having at least one aperture through which the discharge passes. The system further includes a suspension medium disposed downstream of the plasma discharge device. The present invention also relates to a sterilization / decontamination method using the above-described system. By applying a voltage difference between the first electrode and the receiving electrode and radiating a plasma discharge through at least one aperture, a bactericidal active species generated by the plasma is generated. Thereafter, the contaminated fluid to be treated is exposed to the generated sterilizing active species. Particulate matter is collected in the suspension medium from the treated fluid after exposure. Thereafter, the produced bactericidal active species are exposed to a filter and sprayed or bombarded to remove some or all of the collected particulate matter from the filter.

  The methods described herein use organic compound vapors (eg, alcohols) in non-thermal plasma discharges to accelerate and enhance the overall sterilization rate on the surface and in the air stream. This can be applied to various thermal plasma reactors and non-thermal plasma reactors. These reactors can be operated by supplying power continuously or periodically using DC power, AC power, or RF power.

  A capillary discharge type non-thermal plasma reactor using segmented electrodes according to the present invention is a solid or fluid to be treated containing an undesirable chemical agent (for example, element or compound) (for example, liquid, vapor, gas, or a combination thereof) ) Is designed to be exposed to a relatively high density plasma. In such plasma, various chemical reactions can be efficiently performed by various processes (oxidation, reduction, ion-induced synthesis and / or electron-induced synthesis, etc.). Because the energy density can be changed, it is possible to produce a tailored chemical reaction with enough energy to effectively initiate or promote the desired chemical reaction without heating the entire gas. it can. By way of example, the present invention will be described for use in purifying or sterilizing contaminated objects and contaminated fluid streams using a plasma reactor. However, it is within the intended scope of the invention to use the method and associated apparatus for other applications.

  The dimensions of the reaction chamber are such that the time for the contaminants to stay in the plasma region is sufficient to ensure that the contaminants are destroyed to the desired level (eg, to inactivate the contaminants to the molecular level). Can be selected as desired. In addition, when carrier fluid / additive fluid / free fluid is injected into the plasma discharge device, the injection speed and injection position of the additive fluid can be changed as desired, and the additive fluid can be changed through the plasma source region (for example, capillary or slit). The additive fluid may be transferred through an auxiliary supply port that intersects the aperture that emits the plasma discharge. The reaction vessel should be sized so that it can be inactivated without destroying pollutants and biological pollutants, and the residence time is such that the surface, medium and fluid to be treated can be effectively sterilized. Can do. Furthermore, the desired chemical reaction can be achieved by using additive fluid / free fluid / carrier fluid, and the radicals formed can cross the plasma region for a duration sufficient to perform a sterilization or oxidation process. Can exist.

FIG. 1 is an exemplary schematic flow diagram of a plasma sterilization and decontamination system according to the present invention.
The source of contaminated fluid (eg, liquid and / or gas) 155 to be treated may include pathogens (eg, viruses and spores) and / or undesirable chemical compounds (eg, benzene and toluene). Contaminated fluid 155 passes through a decontamination / sterilization device 165 that includes a non-thermal plasma discharge device 105 and a suspension medium 115. The non-thermal plasma discharge apparatus 105 can be one kind of apparatuses having various configurations. For example, corona discharge, barrier discharge, discharge using a capillary dielectric (US Patent Application No. 09 / 738,923, filing date December 15, 2000), discharge using a slit dielectric (November 2, 2001) US patent application claiming priority to US Provisional Application No. 60 / 336,866, dated “Non-Thermal Plasma Slit Discharge Apparatus”, filing date 2002 November 4 (Attorney Docket No. 2790 / 1J670-US1. Non-thermal plasma discharge device is preferable, but thermal plasma discharge device can also be used. However, sterilization in this case Energy is supplied from a high voltage power source to the non-thermal plasma discharge device 105. Depending on the type of plasma discharge desired, the non-thermal plasma discharge device 105 may be For example, a DC power supply, an AC power supply, a high frequency power supply, a radio frequency power supply, a microwave power supply, a pulse power supply can be used. The bactericidal active species are organic radicals and / or ion clusters that are formed as by-products during the generation of the plasma, etc. By exposing the contaminated fluid to the bactericidal active species generated by the plasma, Is substantially inactivated and undesired chemicals are reduced in concentration to become benign compounds.

Four types of reaction mechanisms contribute to the chemical reaction promoted by plasma, which causes the formation of sterilizing active species, which will be described next. What is common to all four types of reaction mechanisms is that they form reactive radicals by dissociation or ionization by electron collision. The four types of reaction mechanisms are listed below.
(1) Oxidation: For example, conversion of CH ₄ to CO ₂ and H ₂ O e ⁻ + O ₂ → e ⁻ + O (3P) + O (1D)
O (3P) + CH ₄ → CH ₃ + OH
CH ₃ + OH → CH ₂ + H ₂ O
CH ₂ + O ₂ → H ₂ O + CO
CO + O → CO ₂
(2) Reduction: For example, reduction from NO to N ₂ + O e ⁻ + N ₂ → e ⁻ + N + N
N + NO → N ₂ + O
(3) Electron-induced decomposition: for example, electron addition to CCl ₄ e ⁻ + CCl ₄ → CCl ₃ + Cl ⁻
CCl ₃ + OH → CO + Cl ₂ + HCl
(4) Ion-induced decomposition: for example, decomposition of methanol e ⁻ + N ₂ → 2e ⁻ + N ₂ ⁺
N ₂ ⁺ + CH ₃ OH → CH ₃ ⁺ + OH + N ₂
CH ₃ ⁺ + OH → CH ₂ ⁺ + H ₂ O
CH ₂ ⁺ + O ₂ → H ₂ O + CO ⁺

  In a preferred embodiment, additive fluid / free fluid / carrier fluid 145 (eg, alcohol such as ethanol or methanol) may be injected into non-thermal plasma discharge device 105 to improve the bactericidal effect and overall plasma chemical reaction. Good. Specifically, the additive fluid / free fluid / carrier fluid increases the concentration of plasma-generated sterilizing active species and reduces the generation of undesirable by-products (eg, ozone pollutants). Thus, the additive / free / carrier fluid can be advantageously used to tailor the chemical reaction of the plasma-generated sterilizing active species for the purpose.

  When an organic / air mixture is used as additive gas / feed gas / carrier gas, further sterilization active species are generated by the chain of subsequent chemical reactions. Each chemical reaction chain will be described with examples.

1) Formation of ions and ion clusters:
e + N ₂ → N ₂ ⁺ + 2e e + O ₂ → O ₂ ⁺ + 2e
N ₂ ⁺ + N ₂ → N ₄ ⁺ O ₂ ⁺ + O ₂ → O ₄ ⁺
N ₄ ⁺ , N ₂ ⁺ + O ₂ → O ₂ ⁺ + Product O ₂ ⁺ , O _n ⁺ + H ₂ O → O ₂ ⁺ (H ₂ O)
O ₂ ⁺ (H ₂ O) + H ₂ O → O ₂ ⁺ (H ₂ O) ₂ → H ₃ O ⁺ (OH) + O ₂
H ₃ O ⁺ (OH) + H ₂ O → H ₃ O ⁺ (H ₂ O) + OH
H ₃ O ⁺ (H ₂ O) + nH ₂ O → H ₃ O ⁺ (H ₂ O) ₂ + (n−1) H ₂ O →
H ₃ O ⁺ (H ₂ O) _h + (n−h) H ₂ O

If hydronium ion clusters are present in the feed gas, ethyl alcohol can be protonated as shown in the following example:
H ₃ O ⁺ (H ₂ O) _h + EtOH → EtOH ₂ ⁺ (H ₂ O) _b + (h + 1−b) H ₂ O

Since ion clusters such as EtOH ₂ ⁺ (H ₂ O) _b have a reasonably long lifetime, the sterilization efficiency is improved. Thus, the ion cluster can withstand transport to the target object to be sterilized and provide an Et group to replace a hydrogen atom in the bacterial DNA. This substitution inactivates the target microorganism. When additive fluid / free fluid / carrier fluid is used, organic ions such as C ₂ H ₄ OH ⁺ , C ₂ H ₃ OH ⁺ , CH ₂ OH ⁺ , CHOH ⁺ , CH ₃ OH ⁺ and C ₂ H ₅ ⁺ It is formed and the bactericidal action is improved according to their lifetime and chemical activity.

2) Free radical formation:
e ⁻ + O ₂ → e ⁻ + O + O (1D)
_{^{e - + O 2 → e -}} + O 2 *
e ⁻ + N ₂ → e ⁻ + N + N, N + O ₂ → NO + O
e ⁻ + N ₂ → N ₂ ^* + e ⁻ , N ₂ ^* + O ₂ → N ₂ + O + O
O + O ₂ + M → O ₃ + M, O ₂ ^* + O ₂ → O ₃ + O

O (1D) + H ₂ O → 2OH

Many other chemical reactions that lead to the formation of NO ₂ , HO _2, and other active species (such as H ₂ O ₂ ) can also be performed.

In the presence of organic matter, organic radicals are formed:
RH + OH → R + H ₂ O, R + O ₂ + M → RO ₂ + M,
RO ₂ + NO → RO + NO ₂ , RO + NO ₂ + M → RONO ₂ + M,
RO + O ₂ → RCHO + HO ₂ ,

Due to the presence of organic substances and oxygen in the plasma, other organic radicals (peroxy RO ₂ , alkoxy RO, acyl peroxyacyl RC (O) OO, etc.) and by-products (hydroperoxide (ROOH), peroxynitrate ( RO ₂ NO ₂ ), organic nitrate (RONO ₂ ), peroxy acid (RC (O) OOH), carboxylic acid (RC (O) OH), peroxyacyl nitrate RC (O) O ₂ NO ₂ etc.) Promoted.

Referring again to FIG. 1, the contaminated fluid 155 after being exposed to the generated plasma is a suspension medium 115 (e.g., a filter, electrostatic precipitator, carbon bed, or fluid) disposed downstream of the plasma discharge device 105. Through any other conventional device used to remove particulate matter from the stream. The pathogen remaining in the plasma discharge apparatus without being completely neutralized or inactivated even after being exposed to the plasma discharge is collected in the suspension medium 115. When these collected contaminants come into contact with the suspension medium 115, they are processed by radicals and ions created as part of the fluid flow by the generated plasma. The compound such as the carbon bed and the microorganisms collected in the suspension medium 115 have a preferable effect of reacting with the plasma-generated sterilization active species that have come into contact with the suspension medium. Specifically, organic by-products and radicals interact with microbial DNA and other constituent blocks deposited on the suspension medium device 115 together with other active species. For example, exposure to plasma-generated bactericidal active species replaces hydrogen atoms in bacterial DNA with alkyl groups C _n H _{2n + 1} , thereby inactivating the microorganism. Alkylation is only one example of a mechanism that provides a bactericidal effect in the described method, and it is believed that other mechanisms and bactericidal active species may exist.

  Optionally, the plasma treated fluid is exposed to a catalyst medium 125 (eg, an ozone catalyst) disposed downstream of the suspension medium 115 or additional suspension medium to remove unwanted residual compounds such as ozone and / or pathogens. The concentration can be further reduced.

  2a is a longitudinal cross-sectional view of a first exemplary embodiment of the sterilization and decontamination unit 165 of FIG. This unit is described in non-thermal plasma capillary dielectric segmented electrode discharge arrangement 235 (US patent application Ser. No. 09 / 738,923 filed Dec. 15, 2000, which is hereby incorporated by reference in its entirety. And a filter 245, which is incorporated herein as a part thereof. This device combined with plasma and filter simultaneously captures and destroys biological particulate matter such as spores and bacteria. The contaminated fluid to be processed is received from the inlet 255 of the sterilization / decontamination unit 165. Capillary dielectric segment electrode 235 includes a first dielectric and a segmented electrode. The first dielectric is provided with at least one capillary, the segmented electrode has a plurality of electrode segments, the electrode segments are arranged in the vicinity of each capillary and are in fluid communication with each capillary . FIG. 2b is a partial cross-sectional view of an exemplary configuration of one of the segmented electrodes of the capillary dielectric segmented electrode 235 shown in FIG. 2a and the capillary associated therewith. The electrode segment is in the shape of a pin 270 with no sharp end, and this pin is disposed in the vicinity of the capillary 275 provided in the first dielectric 280 and is partially inserted into this capillary. Yes. The additive fluid / carrier fluid / free fluid 285 is injected through the electrode into the capillary when the segmented pin electrode 270 is hollow (as shown in FIG. 2b), and when the electrode is solid, the first It is also possible to inject through an auxiliary passage that is provided in the dielectric and intersects the capillary 275. There are many other possible configurations for the segmented electrode, such as a ring or washer placed near the capillary as described in US patent application Ser. No. 09 / 738,923.

  Referring again to FIG. 2 a, the contaminated fluid to be processed passes through a plasma region or passage 225 disposed between the capillary dielectric segmented electrode 235 and the receiving electrode 205. The receiving electrode has a plurality of holes or apertures through which the plasma discharge passes. The filter 245 is disposed between the receiving electrode 205 and the perforated support plate 225.

  During operation, plasma is generated in the plasma region 215 when a voltage difference is applied between the capillary dielectric segmented electrode 235 and the receiving electrode 205. The contaminated fluid to be treated containing undesirable particulate matter enters the plasma region 215 and is exposed to plasma sterilizing active species generated in the region. After the contaminated fluid is exposed to the generated plasma, it passes through the filter 245 where a significant amount of undesirable particulate matter is collected. Filter 245 is continuously or periodically subjected to bombardment, spraying, or exposure of the plasma discharge from capillary dielectric segmented electrode 235. When the plasma-generated sterilizing active species contact the filter 245, the collected unwanted particulate matter is further deactivated, and the treated fluid passes through the holes in the support plate 205 and is sterilized and decontaminated. It is discharged outside from the outlet 265. In this capillary dielectric segmented electrode configuration 235, the spore residence time is relatively long on the surface of the filter, and a relatively high decontamination efficiency can be reliably achieved without reducing the air flow rate.

  Preferably, filter 245 is a HEPA filter with a collection efficiency of about 99.97% for particle size down to about 0.3 microns. Anthrax spores are approximately 3 microns in diameter. Weaponized anthrax particles are only on the order of 1 to 3 microns. Therefore, both types of Bacillus anthracis spores can be collected by the HEPA filter and removed by the organic vapor plasma chemical reaction according to the present invention. To further improve sterilization efficiency according to the present invention, contaminated filters and other suspension media are exposed to bombardment with plasma-generated sterilization active species in the presence of additive gas / carrier gas / free gas such as organic vapor and water vapor. Or attach.

  FIG. 2 shows capillary dielectric type non-thermal plasma sterilization and decontamination. FIG. 3a shows another exemplary plasma sterilization and decontamination system of the slit dielectric discharge type, which is disclosed in US Provisional Patent Application No. 60 / 336,866 filed on Nov. 2, 2001. US Patent Application No .--- filed Nov. 4, 2002, claiming priority, name “Non-Thermal Plasma Slit Discharge Apparatus” (Attorney Docket No. 2790 / 1J670-US1), which is incorporated herein by reference in its entirety as a part of this specification. An additive that improves the chemical reaction of the plasma (in this case, organic vapor) is introduced or injected from the slit dielectric discharge electrode 305, resulting in formation between the slit dielectric discharge electrode 305 and the ground or receiving electrode 315. A plasma chemical reaction occurs in the generated plasma region. For example, the slit discharge electrode is assumed to have 13 dielectric rods 605 as shown in FIG. 3b. However, other electrode configurations can be used if desired. Adjacent dielectric rods 605 are disposed around the inner central cylinder 610 (formed of a conductive or dielectric material) and are spaced apart from one another to form slits 600 that are open at the ends between the rods. To do. Preferably, the inner central cylinder 610 is hollow and has perforations 625 (eg, holes and / or slots) on its periphery. The additive fluid / carrier fluid / free fluid 630 can be injected through the central hollow portion of the cylinder 610 and pass through the perforation 625 at its periphery. The additive 630 then forms between adjacent rods 605 when a voltage difference is applied between the inner central cylinder 610 and the receiving electrode 615 (stored in the second dielectric sleeve 620). The plasma generated in the slit 600 is mixed.

  Referring again to FIG. 3a, the plasma-generated bactericidal active species contains radicals. This radical is carried forward and chemically reacts with the biological material collected in the suspension medium 325 downstream of the plasma discharge device. In order to further reduce any residual ozone-producing sterilizing active species that remain, preferably ozone or other catalyst media 335 is used. A carbon filter 345 may be used to further remove odors and odors that remain without being removed in the plasma region. Additional filters 355, 365 may be added as desired to further remove particulate matter from the fluid to be treated.

  FIG. 4 shows still another embodiment of the in situ plasma sterilization / decontamination system according to the present invention. The system according to this embodiment is somewhat similar to a conventional paper roller or belt conveyor system. A supply drum 405 around which a suspension medium 425 to be processed is wound is disposed at one end, and a receiving drum 410 is disposed at the other end. The suspension medium 425 moves in the direction indicated by the arrow, and is wound around the receiving drum 410 after being treated, bombarded or exposed by the plasma 415 generated by the non-thermal plasma sterilization / decontamination unit 105. The plasma sterilization / contamination removal unit 105 can be of any type of configuration such as corona discharge, barrier discharge, capillary discharge, slit discharge and the like.

  Another embodiment of a non-thermal plasma sterilization and decontamination system according to the present invention is shown in FIGS. 5a and 5b. In this alternative form of sterilization / decontamination system, the in situ sterilization / decontamination unit 505 is movable or displaceable in at least one direction along the rack. For example, the non-thermal plasma sterilization / contamination removal unit 505 shown in FIGS. However, it is conceivable to use a corona discharge type, barrier discharge type or capillary dielectric discharge type plasma sterilization / decontamination unit 505, which is also within the intended scope of the present invention. Further, the non-thermal plasma sterilization / decontamination unit 505 can be displaced in any desired direction or in two or more directions. Instead, while the non-thermal plasma sterilization / decontamination unit 505 is stationary, the row of suspension media 515 to be treated is similarly displaced so that the entire surface is radiated from the non-thermal plasma sterilization / decontamination unit 505. Displacement may also be performed until exposed to or processed by the plasma 510. Although a single non-thermal plasma sterilization and decontamination unit 505 is shown in FIGS. 5a and 5b, any number of units greater than or equal to one can be used to process the filter rows if desired.

Bactericidal active species based on O, H, and N atoms (NO ₂ , H ₂ O ₂ , O ₃ and corresponding radicals such as HO ₂ , OH, etc.) as used in conventional methods and devices Is a disinfectant that is extremely ineffective compared to the by-products, radicals and ions of organic / air plasma in the present invention. Adding additive fluids / free fluids / carrier fluids such as organic compounds to the plasma does not significantly change the properties of the plasma-generated bactericidal active species, but significantly increases the concentration and relative amount of these species. Please pay attention to. One characteristic of the sterilization method of the present invention which is significantly different from the method using the conventional apparatus is that both organic substances and oxygen (air) are present in the gas-discharge plasma. Until now, in the conventional sterilization method, O / H / N type seeds were used, or the direct action of electric field, plasma, and radiation was used. -Utilizing organic active species formed in the discharge plasma.

  Experiments to demonstrate the effectiveness of the method and apparatus of the present invention were performed using standard biological spore strips of Bacillus Subtillis obtained from Raven Laboratories. The test consists of a dielectric capillary segmented electrode having a plurality of wire-like first electrodes inserted into each capillary (inner diameter 0.53 mm) provided in a quartz dielectric, and a quartz tube (outer diameter 3 mm, inner diameter 1.8 mm). This was carried out using a copper wire receiving electrode placed in (). The tip of the first electrode is adjusted to the height of the axis of the receiving electrode. The strip of Bacillus subtilis was placed in contact with the filter media to resemble the state of accumulation and deposition of biological material on the surface of the suspension media. An initial sterilization test on the filter was performed by injecting ambient air (considered as dry air) as the additive fluid. Subsequent tests were performed using various water vapors and alcohol additives, and the results of sterilization of the filter media with and without alcohol in the carrier fluid were compared. Specifically, air was blown into water or methyl alcohol and passed through the capillary of a plasma reactor that sprayed plasma-generated bactericidal active species onto the spore-containing strip.

  In experiments where ambient (considered dry) air was injected as an additive, the effect of non-thermal plasma treatment on spore inactivation became noticeable after a treatment time of about 5 minutes (90% inactivation) Spore growth was found to occur after 12-15 hours. Untreated control spores started to grow within the first 12 hours. Other experiments using water or alcohol additives have confirmed that the addition of methyl alcohol significantly increases the deactivation rate and suppresses the concentration of undesirable ozone pollutants.

  In the capillary discharge segmented electrode type apparatus according to the present invention, various additives (for example, methanol, ethanol) were added to a carrier gas (ambient air) at a constant discharge output (frequency 50 kHz) and incorporated into dry filter paper. The results of the bactericidal efficiency when the spores of Bacillus subtilis are inactivated are shown in the table below.

  From the results in the above table, it is clear that the plasma reactor placed upstream of the filter produces enough radicals to sterilize the air filter surface. The sterilization rate in this process was found to depend on several variables. One such variable is the introduction of dry air and / or other selected additives (alcohol, water, etc.) as additive gas / free gas / carrier gas into the first dielectric. It is to select a chemical reaction. The use of additive fluid / free fluid / carrier fluid increases the sterilization rate, but inactivation of low concentrations of particulate matter can be accomplished without the use of additives. Another variable that affects the sterilization rate is power consumption. That is, the greater the power used for non-thermal plasma generation, the faster the sterilization rate. The separation distance between the place where the plasma is discharged from the plasma discharge device and the suspension medium to be processed is another variable that affects the sterilization rate of the particulate matter.

  Experimental results have shown that spore deactivation has no direct correlation with the concentration of ozone (which is itself a powerful disinfectant) in the plasma-generated discharge offgas. Thereby, it is presumed that the plasma-chemical reaction involves some bactericidal active species generated from the organic substance injected into the plasma zone through the electrode.

  Further experiments were performed using the slit dielectric rod type (R13) discharge electrode design with and without injection of the ethyl alcohol / air mixture through the central tube. The concentrations of ozone and nitrogen oxides were measured without natural air convection between the electrodes. The results of these experiments are shown in the table below. The inactivation efficiency in the 60 Hz system was high and the sterilization rate was significantly faster when an ethanol / air mixture was injected as an additive.

When organic compounds in an air carrier gas (or other oxygen-containing gas) pass through the plasma discharge device, they are compared to the lifetimes of various free radicals and other relatively long-lived (electronic and electronically excited species). And bactericidal active species are produced. Examples of these reaction products include hydroperoxide (ROOH), peroxynitrate (RO ₂ NO ₂ ), organic nitrate (RONO ₂ ), peroxy acid (RC (O) OOH), carboxylic acid (RC (O) OH) , Organic radicals (peroxy RO ₂ , alkoxy RO, acyl peroxyacyl RC (O) OO, etc.) and other bactericidal active species. Some of the oxygen-containing organics (eg ethylene oxide) are known to be powerful fungicides. Placing the filter downstream of the plasma discharge device serves two purposes. That is, the filter is activated by deactivating the contaminated fluid as it passes through the plasma discharge region, and by deactivating collected particulate matter when the plasma-generated sterilizing active species contacts the filter. It is to purify the medium. This is a difference from the prior art. The prior art sterilizes the filter by placing the filter medium between the positive and negative electrodes, which is described in US Pat. Nos. 6,245,132 and 6,245,126. ing. Another advantageous feature of the arrangement of the present invention is that the plasma discharge device can be operated continuously or intermittently.

  The plasma-generated sterilizing active species in the present invention is a conventional sterilizing species generated based on oxygen, hydrogen, or nitrogen (nitrogen dioxide, ozone, hydrogen peroxide, radicals corresponding thereto, and other by-products (hydroxy radicals). It contains a stronger disinfectant than At the same time, the plasma-generated sterilizing active species have a relatively short life and therefore decompose in the sterilization chamber or immediately after the particulate matter is deactivated on the filter. Therefore, there is less harm to the environment or health than conventional chemical disinfectants.

  Thus, while the novel basic features of the present invention have been illustrated, described, and pointed out in the context of a preferred embodiment, those skilled in the art will not be able to illustrate them without departing from the spirit and scope of the present invention. It will be understood that various omissions, substitutions and changes may be made to the shape and details of the apparatus and its operation. For example, all combinations of elements and / or steps that perform substantially the same function in substantially the same way to achieve the same result are specifically intended to be within the scope of the present invention. All replacements of elements in one described embodiment with another embodiment are contemplated and contemplated. It should also be understood that the drawings are not necessarily drawn to scale, but are merely conceptual in nature. Accordingly, it is intended that the invention be limited only as indicated by the claims appended hereto.

  All references, publications, and patents mentioned in this specification are hereby incorporated by reference in their entirety.

FIG. 1 is a schematic view of a non-thermal plasma sterilization / decontamination system according to the present invention. FIG. 2a is a longitudinal cross-sectional view of an exemplary non-thermal plasma sterilization and decontamination system having a capillary dielectric discharge configuration according to the present invention. FIG. 2b exemplarily shows a pin segmented electrode and one of the capillaries combined therewith in the plasma discharge device of the capillary dielectric configuration of FIG. 2a. FIG. 3a is an exemplary cross-sectional view of a non-thermal plasma sterilization and decontamination system having a non-thermal plasma slit dielectric discharge configuration according to the present invention. FIG. 3b is an exemplary slit dielectric R13 rod configuration for the plasma discharge device of FIG. 3a. In FIG. 4, the suspension medium is wound, and after being moved along the path and exposed to non-thermal plasma generated by a non-thermal plasma discharge device, the treated suspension medium is wound on the receiving roller. Show system details. FIG. 5a is a bottom view of an exemplary non-thermal plasma sterilization and decontamination system according to the present invention that is displaceable in at least one direction. FIG. 5b is a side view of the sterilization and decontamination system of FIG. 5a.

Claims (25)

A sterilization and decontamination system,
A plasma discharge device having a first dielectric provided with at least one aperture for passing the plasma discharge;
A sterilization / decontamination system comprising a suspension medium disposed downstream of a plasma discharge device.   The sterilization and decontamination system according to claim 1, further comprising injecting an additive fluid into the first dielectric aperture.   The sterilization / decontamination system according to claim 1, wherein the plasma discharge device is of a capillary dielectric type and at least one aperture is a capillary.   The sterilization / decontamination system according to claim 1, wherein the plasma discharge device is of a slit dielectric type and at least one aperture is a slit.   The sterilization and decontamination system according to claim 1, wherein the additive fluid is alcohol.   The sterilization / decontamination system according to claim 5, wherein the alcohol is ethanol or methanol.   The sterilization / decontamination system according to claim 1, wherein the additive fluid is water vapor.   The sterilization / decontamination system according to claim 1, wherein the additive fluid is dry air.   The sterilization / decontamination system according to claim 1, wherein a catalyst medium is further arranged downstream of the suspension medium.   The sterilization / decontamination system according to claim 1, wherein the plasma discharge is a non-thermal plasma discharge.   The sterilization / decontamination system according to claim 1, wherein the plasma discharge is a corona discharge type.   The sterilization / decontamination system according to claim 1, wherein the plasma discharge is a barrier discharge type. A method of sterilizing and decontaminating a fluid to be processed using a plasma discharge device, the device being disposed in the vicinity of a first dielectric provided with at least one aperture, the at least one aperture and A first electrode in fluid communication with the aperture; a receiving electrode disposed in the vicinity of the first dielectric; and a suspension medium disposed downstream of the plasma discharge device, the method comprising:
Generating a plasma-generating sterilizing active species by applying a voltage difference between the first electrode and the receiving electrode and emitting a plasma discharge through the at least one aperture;
Exposing the treatment target fluid to the generated sterilizing active species;
Collecting particulate matter from the fluid to be treated after exposure to a filter;
A method of sterilizing and decontaminating a fluid to be treated, comprising: removing the collected particulate matter from the suspension medium by spraying the generated sterilizing active species onto the suspension medium.   14. The method of claim 13, wherein the generating step further comprises injecting an additive fluid into the first dielectric aperture.   The method of claim 14, wherein the additive fluid is at least one of air, alcohol, and water.   14. The method of claim 13, further comprising subjecting the fluid to be treated after passing through the suspension medium to the catalyst medium.   The method of claim 13, wherein the plasma discharge device is of a capillary dielectric type.   The method according to claim 13, wherein the plasma discharge device is of a slit dielectric type.   The method according to claim 13, wherein the plasma discharge device is of a barrier discharge type.   The method according to claim 13, wherein the plasma discharge device is a corona discharge type.   The method of claim 13, wherein the plasma discharge device is a non-thermal plasma discharge device.   The method of claim 14, wherein the additive fluid is an alcohol.   24. The method of claim 22, wherein the alcohol is ethanol or methanol.   The method of claim 14, wherein the additive fluid is water vapor.   The method of claim 14, wherein the additive fluid is dry air.

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