Apparatus for inactivation of airborne pathogens and pathogens on the surface of an object

Abstract

An apparatus for the inactivation of airborne pathogens and pathogens on the surface of an object. The apparatus including a housing with an intake region and an exhaust region and an airflow path disposed between the intake and exhaust regions. The apparatus also includes a space within the housing for placement of the object as well as an intake fan and an oxidant generator proximate the intake fan. The apparatus includes an air filter disposed in the airflow path for removing particulates and pathogens and passes the intake air through either or both of an activated carbon filter and a catalyst to convert the oxidant into oxygen.

Claims

1. An apparatus for inactivation of airborne pathogens as well as pathogens resident on an object, the apparatus comprising: a housing with an area for intake of air and an area for exhausting air and an airflow path disposed between the intake and exhaust areas; a space within the housing for placement of the object, the space disposed between the intake and exhaust areas; an intake fan; an oxidant generator with a first end and a second end, the first end proximate the intake fan, the oxidant generator producing the oxidant to inactivate the airborne pathogens that are exposed to the oxidant; a spiral shaped air channel baffle system proximate the first end of the oxidant generator, the baffle system for facilitating turbulent air flow to increase mixing of the generated oxidant and air; at least one air filter disposed in the airflow path; and at least one of an activated carbon filter, and a catalyst to convert oxidant into oxygen, wherein the air and inactivated pathogens are discharged at the area for exhausting air.

2. An apparatus for inactivation of airborne pathogens and pathogens on the surface of an object, the apparatus comprising: a housing with a cavity for intake of air and an area for exhausting air and an airflow path disposed between the intake and exhaust areas; an area within the housing cavity for placement of the object, the area disposed between the intake area and the exhaust area; an air compression apparatus for compressing intake air and increasing the air pressure within the cavity; a receptacle with a bottom wall and at least one side wall, the receptacle containing an aqueous oxidant solution into which the compressed intake air is injected through at least one of the bottom wall, and the at least one side wall; an air filter disposed in the airflow path; at least one of an activated carbon filter, and a catalyst to convert oxidant into oxygen, wherein a portion of the air and inactivated pathogens are discharged at the area for exhausting air; and an enclosed airflow return loop configured to route a non-discharged portion of the air to an area proximate the first end of the oxidant generator.

3. The apparatus of claim 2, wherein a throttle valve is operable to prevent air from escaping through the activated carbon filter, the catalyst, and out through the exhaust area while the housing cavity is pressurized.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Illustrative embodiments of the apparatus disclosed herein are described in detail below with reference to the attached figures, which are incorporated by reference herein and wherein:

(2) FIG. 1 illustrates an elevation view of an embodiment of the exterior of a housing for the apparatus for inactivation of airborne pathogens;

(3) FIG. 2 illustrates a perspective view of an embodiment of the outside housing for the apparatus for inactivation of airborne pathogens;

(4) FIG. 3 illustrates a front view of an embodiment of the internal components for the apparatus for inactivation of airborne pathogens;

(5) FIG. 4 illustrates a perspective view of an embodiment of the internal components for the apparatus for inactivation of airborne pathogens;

(6) FIG. 5 illustrates a detailed perspective view of an embodiment of the lower section internal components for the apparatus for inactivation of airborne pathogens;

(7) FIG. 6 illustrates a detailed perspective view of an embodiment of the middle section internal components for the apparatus for inactivation of airborne pathogens;

(8) FIG. 7 illustrates a detailed perspective view of an embodiment of the top section internal components for the apparatus for inactivation of airborne pathogens;

(9) FIG. 8 illustrates a perspective view of an embodiment with side-by-side chambers for ozone creation and catalyst housing;

(10) FIG. 9 illustrates a detailed perspective view of an embodiment with side-by-side chambers for ozone creation and catalyst housing with the ozone chamber including a heating element for elevating the temperature and a water tank for adding humidity to the ozone rich inlet air stream;

(11) FIG. 10 illustrates a detailed perspective view of an embodiment for use with shipping containers;

(12) FIG. 11 illustrates a detailed perspective view of an embodiment for use with trailers; and

(13) FIG. 12 illustrates a side view of an embodiment for use with trailers showing the apparatus in operation.

DETAILED DESCRIPTION

(14) The apparatus and system disclosed herein is directed to the inactivation or attenuation of pathogens that are present in air and on the surfaces and within the sub-surfaces of objects and materials. The apparatus as disclosed herein operates in two phases, a pathogen inactivation phase and a reactive oxygen species (ROS) decomposition phase.

(15) As seen in FIGS. 1 and 2, the apparatus 10 as disclosed herein consists of a housing 12 with three main sections, a bottom 14, a middle 16, and a top 18. The top section contains three exhaust vents 20 that release the highly filtered air into the environment upon completion of the pathogen inactivation process. The middle section 16 contains a handle 22 on a hinged door 24 that is used at the start of the pathogen inactivation phase to open the middle section 16 and allow for objects or materials to be placed upon a shelf. Once the objects or materials are placed on the shelf, the door 24 to the middle section 16 is closed using the handle 22, in preparation for pressurizing the housing 12.

(16) In the embodiment of the apparatus for inactivation of airborne pathogens shown in FIG. 3, the apparatus contained five corona discharge ozone generators each capable of producing 10 grams of ozone/hour under standard conditions of 1 atm pressure and a temperature of 298 K (25 C). When the apparatus was operated within an enclosure having a volume of 16,000 liters, the ozone generators operating at a flow rate of 160 cubic feet per minute produced 50,000 mg of ozone per hour or 833 mg ozone per minute which is equivalent to a total ozone concentration of 3,125 mg/m.sup.3 or 1,460 ppm within the enclosed space during 1 hour of operation.

(17) When the apparatus is operated at 2 atm pressure with two times the initial concentration of oxygen and with supplemental oxidant production from Ultraviolet radiation in contact with a photochemical catalyst, the production of oxidant will increase proportionately according to the rate equation shown herein. The resulting oxidant concentration attained within the housing charged with oxygen at 2 atm pressure under these conditions will be significantly greater than 20 times the concentration shown by studies to be effective at inactivating pathogens in air and is more than adequate to inactivate pathogens in biofilms and subsurface pores.

(18) When the air containing the excess oxidant was discharged to the environment by passing into contact with the HEPA filter, the activated carbon filter and the fixture containing the ozone destruction catalyst within the apparatus, the ozone concentration in the exhaust gas stream was reduced to less than 13 ppb and thus complied with the threshold standard of 50 ppb ozone in air.

(19) Once the desired pressure is reached, the compressor 40 is switched off and a heater 42 is switched on. The heater is used to heat the air to a temperature less than 100 C., but typically less than 50 C. A fan 44 is turned on at the same time as the heater 42 to circulate the air and facilitate contact of the heated airstream with objects and materials that are contaminated with pathogens. When contacted with the heated airstream, biofluids that may be contained within the sub-surfaces of the objects or materials will be induced to move out of the sub-surfaces and to the surfaces of the objects or materials. At this point, water will vaporize out of the biofluids on the surfaces.

(20) Once the housing cavity is heated to the desired temperature, the heater 42 is switched off, and the fan 44 continues to run. The housing cavity has now been pressurized and heated that any ROS produced will be in an environment most conducive to inactivating pathogens. At this point, the corona discharge generator 46 is switched on, producing predominantly ozone, with a small amount of another ROS.

(21) As the corona discharge generator 46 is switched on, the ultraviolet light source emitting 185 nm wavelength light 48 is also switched on. As the ultraviolet light of 185 nm wavelength is created, the light travels throughout the housing cavity, reaching an area coated with a photocatalyst 50. As light contacts the photocatalyst 50, a mixture of ozone, superoxide, and hydroxyl radicals is released. To ensure a continuously desirable volume of ROS is produced by the photocatalyst, a set of nozzles 52 releases water vapor into the housing cavity to ensure that the air is at the proper humidity to maximize the production of ROS. The fan 44 continues to run, ensuring the airstream within the housing cavity is constantly mixing with the ROS that are produced by the corona discharge generator 46 and the ultraviolet light source emitting 185 nm wavelength light 48 in contact with the photocatalyst 50.

(22) This pressurized air and ROS mixture encounter the pathogens on the surfaces and sub-surfaces of the objects or materials placed on the shelf, inactivating those pathogens. The longer the pressurized air and ROS mixture is circulated throughout the housing cavity, and the longer the ROS generators operate, the greater the pathogen inactivation rate. The time for contacting the contents within the housing 12 with the pressurized air and ROS mixture is specifically selected for the materials and objects to be treated by the apparatus.

(23) Once the desired period has elapsed, the pathogen inactivation phase has ended, and the ROS decomposition phase begins. During this phase, the fan 44 continues to circulate the airstream and the heater 42 is switched on at a temperature between 50 C. and 100 C. Although ozone is more stable than related other ROS, its rate of decomposition will gradually increase with an increase in temperature between 20 C. and 100 C. At around 100 C. the rate of decomposition of ozone begins to rise at an accelerating rate with an increase in temperature, and at around 120 C., ozone rapidly decomposes to oxygen. Because some studies have shown that ozone can undergo explosive decomposition at around 105 C. at concentrations higher than 13%, heating of the airstream in the apparatus to facilitate decomposition of ozone is typically carried out at temperatures below 100 C.

(24) During this heating phase, it is only necessary to heat the airstream to the selected temperatures because all the excess ROS is present in the airstream, and not on or in the objects and materials contained within the housing. A second ultraviolet light emitting source 54 having wavelengths between 240-315 nm and preferably at 254 nm is also switched on to facilitate further decomposition of ozone. The second ultraviolet light emitting source 54 also provides an additional benefit in that such wavelengths emitted are within the UVC spectrum and have a strong germicidal effect even in environments free of ROS.

(25) The provision for the use of a second ultraviolet light emitting source 54 thus provides two functions; to decompose excess ROS remaining and continue to inactivate pathogens that may have survived the previous phase. As the airstream is exposed to the combination of heat at a temperature above 50 C. and the selected wavelengths of ultraviolet light, the ozone in the airstream begins to rapidly decompose into oxygen and water vapor.

(26) After a period optimized for the decomposition of ozone, the heater 42 and the ultraviolet light emitting source 54 are switched off and the throttle valve 32 is engaged. The airstream is then propelled through a HEPA filter 58 as the pressures within the housing and the ambient environment begin to equalize. The HEPA filter 58 removes particles typically 0.3 microns and larger from the airstream. Because these larger airborne particulates are oftentimes colonized by much smaller pathogens, such as viruses, capturing the particulate matter in the HEPA filter 58 prevents the return of some of the inactivated pathogens or their residual components to the ambient air. At this point a high percentage of the pathogens in the airstream have been inactivated by the apparatus.

(27) After passing through the HEPA filter 58, the airstream passes through the open throttle valve 32 and enters the activated carbon filter 34 where it reacts with ozone to produce oxygen, carbon dioxide and water vapor. The airstream continues to pass through activated carbon filter into the ozone destruction catalyst 36 which completes the removal of ozone to meet the ALARA (as low as reasonably achievable) threshold of less than 50 ppb ozone in the treated air that is emitted from the apparatus. With the fan 44 still engaged, the compressor 40 is started to draw fresh air from the environment to sweep through the housing and flow through the HEPA filter 58, the fully open throttle valve 32, and the ozone destruction catalyst 36 for a set period. The fan 44 is then switched off and the housing opened so that the disinfected objects and materials can be removed.

(28) It is critical that the pathogens be exposed to the ROS for sufficient time and at a concentration that is high enough to allow the ROS to adequately inactivate the pathogens. As describe herein, the rate and effectiveness of a process to inactivate pathogens in biofilms and subsurface pores of materials and objects is increased by increasing the concentration of the ROS in contact with the pathogens. Similarly, the choice between the various ROS to be used in a pathogen inactivation device is dependent upon both the oxidation potential and stability of each individual ROS.

(29) Radical ROS typically have higher oxidation potentials and higher reactivity but also much shorter half-lives compared to non-radical ROS. For example, at room temperature and in a clean vessel, the half-life of ozone may range from 20 to 100 hours in dry air. Comparatively, studies have shown that the half-life of a hydroxyl radical is around 1 nanosecond and the half-life of superoxide is around 5 seconds. While ozone is much more stable than a hydroxyl radical, it has a lower oxidation potential (2.07 v) than a hydroxyl radical (2.80 v). Rather than selecting one individual ROS based on stability or oxidation potential, the apparatus uses a mixture of highly reactive, short-lived ROS with less reactive but more stable ROS to inactive pathogens on the surfaces and in the sub-surface pores of objects and materials contaminated with biofilms.

(30) As seen in the perspective view of FIG. 4, the housing 12 is pressurized by turning on the compressor 40 to pull air through the air inlet 28 and into the housing cavity 30. The compressor 40 will typically be of a lower pressure, tankless variety capable of reaching pressure up to 4 atm in a small footprint. Next, throttle valve 32, as shown in FIG. 3, is closed to prevent air from escaping through the activated carbon filter 34, the ozone destruction catalyst 36, and the exhaust vent 20 while pressurizing the housing. The compressor 40 continues to run until the desired pressure is reached, between 1 to 4 atm but typically around 1.5 atm. As the pressure increases, the air within the housing cavity is forced deeper into the sub-surfaces of the materials and objects to be disinfected.

(31) FIG. 5 shows an enhanced drawing of the bottom section of the apparatus. The fan 44 shown in the figure is a commercial fan typical of those used to move air throughout enclosed spaces and through conduits. The heater 42 consists of a heating element coil that converts electricity into radiant heat. This heater may be of any type of radiant heater that utilizes electricity to produce heat. The corona discharge generator 46 utilized may be any device capable of producing ozone and other ROS via the use of corona discharge. The corona discharge generator 46 can be a single device, or may be multiple corona discharge producing devices operating simultaneously. This will be dependent upon the size of the housing cavity, as a larger cavity can accommodate a larger corona discharge device or a larger number of corona discharge devices. Typically, the housing cavity is sized based on the size of the objects or materials that will need to be placed on the shelf within the cavity.

(32) FIG. 6 shows an enhanced drawing of the middle section of the apparatus. The ultraviolet light emitting sources 48 and 54 will typically consist of a set LED lights emitting light at the desired wavelength. The photocatalyst 50 may be any photocatalyst capable of producing a mixture of ROS, but will typically be titanium dioxide. The number of ultraviolet sources, as well as the photocatalyst area 50, can be varied depending on the size of the housing cavity. This is like the corona discharge generator 46 as described above.

(33) FIG. 7 shows an enhanced drawing of the top section of the apparatus. The top section of the apparatus contains two major componentsan activated carbon filter 34 and a fixture containing catalyst 36 that catalyzes the conversion of ROS into oxygen. The activated carbon filter 34 can be any manner of filter known to those skilled in the art including, an activated carbon block, activated carbon granules in a canister or activated carbon impregnated onto a substrate. The volume of the filter is sized in proportion to the airstream flow rate and space velocity. The ozone destruction catalyst 36 is designed to convert all ROS into oxygen and water vapor and which consists primarily of metal oxides impregnated upon various substrate supports. The construction and the composition of the ROS destruction catalyst and substrate are well known to those skilled in the art and are not described in detail herein.

(34) FIG. 8 details a perspective view of an embodiment of the apparatus 10 for inactivation of airborne pathogens and pathogens on the surface of an object. In this embodiment there are side-by-side chambers for ozone creation and catalyst housing. Operationally, air is pulled into the housing 12 by the air inlet fan 28 and traverses over the corona discharge generator 46. After pathogen inactivation, the airstream passes through the open throttle valve 32 and enters the ozone destruction catalyst 36 where it reacts to produce oxygen, carbon dioxide and water vapor to meet the ALARA (as low as reasonably achievable) threshold of less than 50 ppb ozone in the treated air that is emitted from the apparatus at the exhaust fan 20.

(35) FIG. 9 illustrates an additional embodiment of the apparatus 10 for inactivation of airborne pathogens and pathogens on the surface of an object. This perspective view details the side-by-side chambers for ozone creation and catalyst housing with the ozone chamber including a heating element 42 for elevating the temperature and a water tank 51 with a set of spray nozzles 52 for adding humidity to the ozone rich inlet air stream.

(36) FIG. 10 illustrates an additional embodiment of the apparatus 10 for use with shipping containers. The shipping container walls serving as the housing 12. FIG. 10 reveals that one of the longitudinally disposed ends of the shipping container housing 12 includes an air inlet vent 28 and an exhaust vent 20. An interior portion of the shipping container housing 12 is dedicated to the generation of ozone for use in inactivating the pathogens. A separate compartment, as detailed above, is utilized to convert the ROS to oxygen before being expelled to the ambient atmosphere at the exhaust vent 20.

(37) FIG. 11 illustrates a detailed perspective view of an embodiment for use with trailers from a tractor-trailer combination. With an appearance much like a reefer trailer, the apparatus 10 for inactivation of airborne pathogens and pathogens on the surface of an object is disposed on the vertical wall of the trailer most closely spaced from the tractor in the position where a refrigeration unit is normally located. As seen in FIG. 11, the trailer mounted apparatus 10 includes a housing 12 as well as an ambient air inlet 28 and an exhaust vent/fan 20.

(38) FIG. 12 depicts the interior space of a trailer loaded with boxes/packages that require inactivation of pathogens on the surface and possibly in the interior portions of the boxes/packages. The inactivation apparatus 10 as with the previously referenced embodiments utilizes a housing 12 providing an air inlet 28, a throttling valve 32, a corona discharge generator 46, and an ozone destruction catalyst 36.

(39) Another embodiment (not shown) of the apparatus 10 for inactivation of airborne pathogens utilizes an aqueous oxidant instead of gaseous oxidant. An aqueous oxidant, such as hydrogen peroxide, is a strong oxidizer and is very effective in achieving pathogen inactivation. Studies have demonstrated that with aqueous oxidant significant pathogen inactivation can be achieved in short periods, ranging from 20 seconds to five minutes with an oxidant concentration of 0.1 mg/L to 4.68 mg/L. Disclosed herein is an embodiment of the apparatus for inactivation of airborne pathogens wherein the air stream is bathed in a reservoir of aqueous oxidant.

(40) Any off-gassing of oxidant from the aqueous solution is removed through a reaction using a metallic catalyst, such as manganese dioxide as with the case for the use of the other ROS. Prior to the airflow passing through the manganese dioxide catalyst the air and airborne pathogens encounter a HEPA filter that captures particulates and pathogens colonized on the particulate matter that are larger than 0.3 microns. As previously indicated, those particles that are captured within the HEPA filter are continuously bathed in the oxidant and very likely inactivated so that upon removal and discarding of the HEPA filters there is a greatly diminished prospect of exposure to active pathogens.

(41) In still another embodiment, the housing contains a rotating drum equipped with baffles into which the objects and materials to be disinfected are placed prior to being treated by the apparatus. The rotating drum maximizes contact between the pressurized mixture of air and oxidants and the enclosed materials and objects to be decontaminated while they are tumbled about during the inactivation stage of the process, and serves to fully expose the surfaces of such materials to the oxidants in the airstream and the ultraviolet radiation generated within the housing. This mode of operation with the rotating drum is especially suited for the treatment of soft materials consisting of clothing, bedding, masks, gowns, towels and the like.

(42) In a final embodiment of the apparatus as disclosed herein, a reservoir containing water is used to contain water that is mechanically pumped into the airway path proximately the intake fan or air compressor to increase the relative humidity of the air. An appropriately sized spray nozzle or nozzles would be required to achieve the appropriate water droplet particle size. Studies have revealed that maximum anti-viral efficacy requires a short period of high humidity (>90% relative humidity) after the attainment of peak oxidant gas concentration (20-25 ppm). In the studies note above, all twelve viruses tested, on different hard and porous surfaces, and in the presence of biological fluids, could be inactivated by at least 3 log 10, in the laboratory and in simulated field trials. As has been extensively detailed above, the oxidant is subsequently decomposed to oxygen by a metallic catalyst prior to ejection at the exit area of the apparatus.

(43) Any different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of the disclosed technology. Embodiments of the disclosed technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from its scope. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from the scope of the disclosed technology.

(44) It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.