Air Treatment and Disinfection Systems

Abstract

Disclosed is a system for treating air drawn from within a room or enclosed space for discharge back into a room or other enclosed space or elsewhere, wherein the air is passed through a plurality of

Description

It is now well-established that the airborne transmission of pathogens (viruses including SARS-COV-2, influenza and rhinovirus, as well as bacteria including tuberculosis, and fungal spores) commonly occurs in closed, confined or poorly ventilated spaces. The rates of such airborne transmission can be increased by the mixing of recirculated air by installed heating, ventilation and air conditioning (HVAC) systems and exhaled, improperly filtered, recirculated air will serve to spread viruses and other pathogens through the working areas, as has been observed with the levels of infection. The problem of the recirculation of viruses and other pathogens by existing air conditioning system installations is well documented, and can include: 1) Gram-positive bacteria: Bacillus sp., Enterococcus sp., Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus sp. 2) Gram-negative bacteria: Acinetobacter sp., Corynebacterium sp., Enterobacter sp., Escherichia coli, Klebsiella sp., Pseudomonas sp., Serratia sp., Stenotrophomonas sp. 3) Fungi: Alternaria sp., Aspergillus sp., (A. niger), Candida sp., Chaetomium sp., Cladosporium sp., Cryptococcus sp., Penicillium sp., Rhodotorula sp. This airborne transmission of pathogens can be significantly reduced by cleaning the air that is being recirculated through these systems to remove airborne virus particles, bacteria spores, particulates and exhaled liquid droplets (>5|jm) and aerosols (droplets <5pm). Aerosols consist of very small droplets and droplet nuclei that remain suspended in the air for much longer than large droplets. There are a number of solutions and products marketed to remove airborne particulates or to kill pathogens within buildings and other enclosed spaces, which offer varying degrees of efficiency, power consumption and maintenance requirements. Filters tend to decrease in efficiency in increase in power consumption over time as they become clogged. SARS-CoV-2 transmission is particularly prevalent inside crowded, confined indoor spaces such as workplaces (offices, factories) and other indoor settings, such as restaurants, parties, shopping centres, worker dormitories, dance classes, cruise ships, vehicles and aircraft, where coughing, speaking, shouting or singing produce a mixture of both droplets and aerosols in a range of sizes. High levels of SARS-COV-2 infections have been reported in meat processing plants in a number of countries due to the close proximity of workers who spend all day in air conditioned, chilled environments, where the lower temperatures facilitate the relative longevity of the virus. Meat processing plant are supposed to maintain a minimum number of air exchanges per hour, however often their air conditioning / ventilation systems have not been designed to be able to achieve increased volumes of air exchange throughout working areas whilst allowing for improvements in filtration efficiency. Airborne transmission through larger water droplets (> 5pm) that are expelled by coughing and sneezing fall to surfaces no further than 1-2 metres from an infected person. . Smaller droplets (< 5pm) and particles generated through coughing, sneezing or talking may stay airborne for hours and be transported much longer distances. Small particles such as droplet nuclei or solid residues are formed from droplets as they evaporate and desiccate. The coronavirus particles are 0.08-0.16pm in size and remain active in common indoor air conditions for up to three hours and for two to three days after settling on room surfaces. These small particles can stay airborne and be transported long distances by airflows in rooms or via air ducts of ventilation and air conditioning systems. The exposure time for aerosol droplets of sizes <5pm is up to 3 hours (10,800 seconds), whilst the exposure time for aerosol droplets of sizes >10pm is approximately 6 seconds. Dilution reduces the concentration of infectious agents in a space by increasing the amount of outside air brought into that space. Dilution does not destroy the bacteria, but rather reduces the probability of transmission by spreading the bacteria throughout a larger volume of air. Recirculation air in offices and other buildings, with air being introduced at high level and extracted near floor level also serves to aid the concentration / distribution of pathogens at lower levels. Filtration is able to reduce the concentration of infectious agents in a space by passing the air through a high-efficiency particulate air (HERA) filter that captures 99.97% of aerosols with particle size >0.3pm bacteria and viruses (and other particles), thereby removing them from circulation. HEPA filtration imposes additional operating costs due to the increased fan power required to push air through HEPA the filter, which further increases overtime as the filter media becomes fouled, and the cost of periodic replacement and disposal of the filter media. Ultralow particulate air (ULPA) filters can capture 99.99% of aerosols with particle sizes >0.12pm, but require even higher fan powers than HEPA filters and even more frequent replacement and disposal of the filter media. The use of local air purifiers can help minimize the risks of infection caused the spread of airborne infectious agents. These issues may be substantially mitigated by the retrofitting of high-performance air purification systems into existing HVAC installations or the installation of standalone air purification systems into buildings and other enclosed spaces to remove and destroy airborne infectious agents. Present Invention The present invention implements the application an innovative sequence of at least four technologies within a single air purification system to disinfect and remove particulates from the air in closed, confined or poorly ventilated spaces or from the air being circulated / recirculated through heating, ventilation and air conditioning systems. Such air purification systems may either be installed within airflow of a heating, ventilation or air conditioning system or contained within enclosed cabinets and include internal / extemal electrically operated fans to draw air in through the air purification system (s) before releasing it back into the local environment, room or other enclosed space. The innovative sequence of technologies ensures that not only is the air disinfected, but also almost all of the particulates, liquid droplets and pathogens are removed and deactivated / destroyed. The selected technologies utilised in the sequence offer a number of important benefits when compared with high efficiency particulate air (HERA) filters or ultra-low particulate air (ULPA) filters, which impact airflow and therefore result increased energy consumption due the increased resistance to airflow within the HVAC systems. The selected sequence of technologies has been selected to minimise any risk of irritation, allergic reaction or other effect upon eyes, mucous membranes or skin of the occupants of a room or other enclosed space, as might be experienced if ozone, cold plasma or fogging is used alone to disinfect air volume within such room or other enclosed space. The principal technologies integrated into the present invention are: 1. The introduction of an oxidising agent and / or other biocide in gaseous form or as a liquid atomised, preferably using electrospray or other liquid atomising technology into the airflow within a heating, ventilation, air conditioning or air recirculation system from ultraviolet lamps being installed within the system. Such ultraviolet lamps emitting light having a specific wavelength or wavelengths in the range of 180nm to 270nm, which will simultaneously deactivate / destroy a majority of the viruses, bacteria and fungi carried within the airflow through the system. The oxidising agent, whether introduced in gaseous or aerosol form acts to deactivate / destroy viruses, bacteria and fungi that may remain after the ultraviolet treatment. Ideally, the airflow with the oxidising agent and / or biocide is then guided through a chamber and / or pipework to create turbulence / mixing effect within the airflow. 2. Following the previous treatment, the airflow is directed through two or more stages of electrostatic precipitator to remove airborne particulates, including virus particles, bacteria, fungi, spores and liquid droplets, which may be carrying viruses and / or bacteria. The electrodes in the electrostatic precipitators are designed so that they are self-cleaning to minimise system maintenance interventions. Technologies utilised within innovative sequence: 1. Two or more separate stages of ultraviolet light, at least one prior to, and at least one 105 subsequent to particulate and droplet removal using electrostatic precipitation, where both stages may utilise the same or different wavelengths of ultraviolet light. 2. Addition of an oxidising agent, in gaseous form and / or atomisation of oxidising agent and / or biocide in liquid form and / or atomisation of water, using fine bore nozzles, or an ultrasonic or electrospray assembly. 110 3. At least two single or multiple-stage electrostatic precipitator (sub)systems installed in series. To construct effective air treatment systems that ensure the effective destruction / removal of viruses and other pathogens, as well as removing airborne particulates including dust and pollen, it is necessary to integrate combinations of different technologies that are capable of 115 biocidal and particulate / droplet removal. It is of paramount importance, that not only does a selected combination of technologies ensure the required destruction / removal of the viruses, pathogens and airborne particulates / droplets, but it is cost effective in terms of capital, installation, operation and maintenance, as well as being energy efficient. 1. A first stage of treatment using either ultraviolet light irradiation to kill viruses and other 120 pathogens at a particular wavelength, e.g,187nm that also creates a small amount of ozone in the air stream, or alternatively ultraviolet light irradiation at a particular wavelength, e.g. 254nm, in combination with separate ozone generation that introduces a low concentration of typically 3-4ppm into the airstream to act as biocide and kill viruses and other pathogens. 125 2. As a second stage, water, or a solution of an oxidising agent or biocide, is atomised / sprayed into the air stream prior to its passage through a series of two or more electrostatic precipitators designed to remove the majority of airborne particulates and droplets (>0.1 pm), the first electrostatic precipitator (or set thereof) removes dust, airborne particles of fats, oils and greases, liquid droplets, etc., including some of the virus particles, 130 bacterial and fungal spores with a lower power consumption than HEPA filters (>0.3pm) and does not experience any significant decrease in performance / degradation due to fouling. The second electrostatic precipitator (or set thereof) ensures removal of most of the dust, airborne particles of fats, oils and greases, liquid droplets, etc., virus particles, bacterial and fungal spores remaining after the first electrostatic precipitator (or set 135 thereof). The electrodes have pneumatically / electrically driven vibrators attached, which are operated periodically to shake adhering particles into a collection hopper / chamber. Alternative designs of electrostatic precipitator to further increase rates of virus and pathogen removal, especially for the first stage may utilise: i) Porous collection electrodes, which are wetted with a disinfectant solution of hydrogen peroxide and / or ozone in water (the ozone be produced using a small ozone generator) or hypochlorous acid, etc., and the disinfectant solution is filtered using suitable ceramic or other filter elements and recirculated; or ii) Vertical collection electrodes, which are wetted with a disinfectant solution of hydrogen peroxide and / or ozone in water (the ozone be produced using a small ozone generator) or hypochlorous acid, etc., and the disinfectant solution is filtered using suitable ceramic or other filter elements and recirculated; or iii) Vertical, cooled collection electrodes, with a disinfectant solution of hydrogen peroxide, sodium or potassium persulphate and / or ozone in water or hypochlorous acid, etc., being atomised into the influent air stream beneath the cooled electrodes, upon which the atomised disinfectant solution condenses, and the solution is filtered using suitable ceramic or other filter elements and recirculated. Alternative variations of the present invention that are fitted with wetted / chilled collection electrodes may utilise of disinfectant solutions produced by electrolysing solutions of sodium or potassium sulphate in water using boron doped diamond or mixed metal electrodes to form peroxygen compounds: hydrogen peroxide, sodium or potassium persulphate, etc., which have biocidal properties and are injected / atomised into the air flow ahead of the electrostatic precipitators and also into the collection hoppers / chambers where particulates and droplets removed by the electrostatic precipitators are collected to ensure the destruction of virus particles, bacterial and fungal spores. Baffle plates or similar are installed after the injection / atomising injection points to ensure effective mixing / distribution of the ozone throughout the air volume. Alternatively, or additionally, the second electrostatic precipitator (or set thereof) may include electrode structures + power supplies that are designed specifically to generate ozone at the electrodes to ensure localised destruction of virus particles, bacterial and fungal spores; and / or include an arrangement of a series of UV-C lamps (either quartz or LED with quartz windows) installed after the electrostatic precipitators. These UV-C lamps have two functions: i) To irradiate and destroy almost all virus particles (>99.99%), bacterial and fungal spores that might remain in the air flow after electrostatic precipitation; and ii) To remove a potential work place hazard by the removal of the majority ozone remaining in the air flow through its transformation into oxygen gas - specific wavelengths of electromagnetic radiation present in UV-C light to break open the unstable bonds in the oxygen atom triplets that comprise the ozone molecules, which then reform to normal oxygen gas comprising of molecules, each containing two oxygen atoms. Other variations of the present invention may include a sensor or sensors to control and activate and / or deactivate one, or more, or all of the stages in the sequence of technologies implemented within the current invention, and / or increase / decrease periods of activation, treatment intensity and / or other operating parameters of one, or more, or all stages in the sequence of technologies implemented within the current invention. Where such sensors may amongst other measured parameters detect changes in carbon dioxide concentrations and / or temperature and or humidity within the air flow and / or room, building or facility, movement and / or numbers of individuals entering or leaving such room building or facility. Further variations to present invention may include capabilities for the collection, storage and processing of data, including the implementation of statistical analysis of Machine Learning / Artificial Intelligence techniques, collected by sensors to facilitate the monitoring, prediction, display locally and / or remotely, automation and optimisation of the treatment within the airflow and / or room building or facility. Three examples illustrating how the present invention may be put to use are set out below, and these should be read with reference to the corresponding accompanying drawings, showing diagrammatically the systems for carrying out the method of the respective example. In the Drawings: Figure 1 is a process flow diagram for an implementation of the present invention for the treatment of recirculated airflow using two stages of ultraviolet treatment with wavelengths concentrated within particular narrow ranges of the electromagnetic wave spectrum and two stages of electrostatic precipitation with dry electrodes described in Example 1; Figure 2 is a process flow diagram for an implementation of the present invention for the treatment of recirculated airflow using ozone gas, one stage a of ultraviolet treatment with wavelengths concentrated within particular narrow range of the electromagnetic wave spectrum and two stages of electrostatic precipitation with dry electrodes as described in Example 2; and Figure 3 is a process flow diagram for an implementation of the present invention for the treatment of recirculated airflow using two stages of ultraviolet treatment with wavelengths concentrated within particular narrow ranges of the electromagnetic wave spectrum and two stages of electrostatic precipitation with porous collection electrodes that are wetted with an aqueous solution of a biocide, which is continuously filtered and recirculated as described in Example 3; and EXAMPLE 1 101 Airflow for treatment 102 Arrangement of lamps emitting ultraviolet light with wavelengths concentrated between 170nm and 200nm 103 Baffle plate arrangement 104A Ionisation electrodes for first electrostatic precipitator 104B Collection electrodes for first electrostatic precipitator 105A Ionisation electrodes for second electrostatic precipitator 105B Collection electrodes for second electrostatic precipitator 106 Arrangement of lamps emitting ultraviolet light with wavelengths concentrated between 200nm and 270nm 107 Treated airflow The airflow for treatment is transported in the into the treatment system, which consists of the sequence of treatment processes listed above, by fans or other transport mechanism, where it passes across an arrangement of lamps, which emit high intensity ultraviolet light with wavelengths concentrated between 170nm and 200nm. The ultraviolet at these particular wavelengths is both directly biocidal to virus particles, bacteria and fungi, and also causes ionisation of molecules of oxygen gas causing them to dissociate into electrically charged oxygen ions that are biocidal, and some of these ions reform as molecules of ozone gas, which is an oxidising agent and is biocidal / virucidal. The airflow emerges from the arrangement of lamps and passes through a baffle plate arrangement, which creates turbulence and ensures effective mixing of airflow to maximise the probabilities of collisions / interactions between the electrically charged oxygen ions and ozone gas molecules with the remaining active virus particles, bacteria and fungi to increase the rates of destruction of these in the airflow. After the baffle plates, the airflow passes through first one stage of electrostatic precipitation, which removes a majority of particulates, droplets and dead / inactive / active virus particles, bacteria and fungi. Next the airflow passes through a second stage of electrostatic precipitation, which removes the majority of any remaining particulates, droplets and dead / inactive / active virus particles, bacteria and fungi. Finally, the airflow passes across an arrangement of lamps, which emit high intensity ultraviolet light with wavelengths concentrated between 200nm and 270nm. Ultraviolet light at these particular wavelengths is both directly highly biocidal to virus particles, bacteria and fungi, and also destroys ozone molecules, causing them to dissociate and breakdown into oxygen molecules, thereby removing hazardous ozone gas that might remain after previous treatment stages. EXAMPLE 2 201 Airflow for treatment 202 Introduction of ozone gas from generator 203 Baffle plate arrangement 204 Atomising nozzles introducing atomised water droplets into airflow 205A Ionisation electrodes for first electrostatic precipitator 205B Collection electrodes for first electrostatic precipitator 206A Ionisation electrodes for second electrostatic precipitator 206B Collection electrodes for second electrostatic precipitator 207 Arrangement of lamps emitting ultraviolet light with wavelengths concentrated between 200nm and 270nm 208 Treated airflow The airflow for treatment is transported in the into the treatment system, which consists of the sequence of treatment processes listed above, by fans or other transport mechanism, where ozone gas, which is biocidal to virus particles, bacteria and fungi, is introduced from an ozone generator and mixed into the air flow. Next the airflow is passes through a baffle plate arrangement, which creates turbulence and ensures effective mixing of airflow to maximise the probabilities of collisions / interactions between ozone gas molecules and active virus particles, bacteria and fungi to increase the rates of destruction of these in the airflow. After the baffle plates, the airflow passes through firstly one stage of electrostatic precipitation, which removes a majority of particulates, droplets and dead / inactive / active virus particles bacteria and fungi. Next the airflow passes through a second stage of electrostatic 45 precipitation, which removes the majority of any remaining particulates, droplets and dead / inactive / active virus particles, bacteria and fungi. Finally, the airflow passes across an arrangement of lamps, which emit high intensity ultraviolet light with wavelengths concentrated between 200nm and 270nm. Ultraviolet light at these particular wavelengths is both directly highly biocidal to virus particles, bacteria and fungi, and 50 also destroys ozone molecules, causing them to dissociate and breakdown into oxygen molecules, thereby removing hazardous ozone gas that might remain after previous treatment stages. EXAMPLE 3 301 Airflow for treatment 302 Arrangement of lamps emitting ultraviolet light with wavelengths concentrated between 170nm and 200nm 303 Baffle plate arrangement 304 Pump to supply biocide solution to porous electrostatic collection electrodes 305A Ionisation electrodes for first electrostatic precipitator 305B Porous collection electrodes for first electrostatic precipitator 306A Ionisation electrodes for second electrostatic precipitator 306B Porous collection electrodes for second electrostatic precipitator 307 Biocide solution recycle pump 308 Biocide solution filtration subsystem 309 Biocide solution reservoir tank 310 Biocide solution make-up subsystem 311 Arrangement of lamps emitting ultraviolet light with wavelengths concentrated between 200nm and 270nm 312 Treated airflow 55 The airflow for treatment is transported in the into the treatment system, which consists of the sequence of treatment processes listed above, by fans or other transport mechanism, where it passes across an arrangement of lamps, which emit high intensity ultraviolet light with wavelengths concentrated between 170nm and 200nm. Ultraviolet light at these particular wavelengths is both directly biocidal to virus particles, bacteria and fungi, and also causes ionisation of molecules of oxygen gas causing them to dissociate into electrically charged oxygen ions that are also biocidal / virucidal, and some of these ions reform as molecules of ozone gas, which is an oxidising agent and is biocidal / virucidal. Next the airflow is passes through a baffle plate arrangement, which creates turbulence and ensures effective mixing of airflow to maximise the probabilities of collisions / interactions between ozone gas molecules and electrically charged oxygen ions with the active virus particles, bacteria and fungi to increase the rates of destruction of these in the airflow. After the baffle plates, the airflow passes through two stages of electrostatic precipitation with porous electrodes, which are continuously wetted with a pumped flow of a solution of biocide in water, e.g. sodium hypochlorite solution, chlorine dioxide or quaternary ammonium compounds, etc., to remove the majority of particulates, droplets and dead / inactive / active virus particles bacteria and fungi. The biocide solution is pumped away from the electrodes and through a filtration subsystem before being returned to a biocide solution reservoir tank. Next the airflow passes through a second stage of electrostatic precipitation, which removes the majority of any remaining particulates, droplets and dead / inactive / active virus particles, bacteria and fungi. Finally, the airflow passes across an arrangement of lamps, which emit high intensity ultraviolet light with wavelengths concentrated between 200nm and 270nm. Ultraviolet light at these particular wavelengths is both directly highly biocidal to virus particles, bacteria and fungi, and also destroys ozone molecules, causing them to dissociate and breakdown into oxygen molecules, thereby removing hazardous ozone gas that might remain after the previous treatment stages. Further Embodiments are set out in the following clauses: Clause 1. The present invention is for a system to treat air drawn from within a room or other enclosed space for discharge back into the room or other enclosed space or elsewhere, or for air drawn from outside or other exterior environment and discharged into a room or other enclosed space or elsewhere, whereby several treatments, including the application of ultraviolet light, ozone and / or other oxidising chemicals and electrostatic precipitation are applied to the flow air in sequence after it has been drawn from the room or other enclosed space such that the majority of pathogens, including viruses, bacteria and fungi are destroyed, and these, together with airborne particulates, including dust and pollen, are removed from the airflow. Clause 2. A system according to Clause 1 where the sequence of treatment processes includes an initial application of ultraviolet light in the wavelength range of 180nm to 190nm from sources installed within the path of airflow prior to electrostatic precipitation, such that not only are pathogens in the airflow are irradiated with this ultraviolet light and many are destroyed / inactivated, but ozone is also generated by these sources of ultraviolet light at a low concentration, which also exhibits additional biocidal activity against the pathogens. Such ultraviolet lamps emitting light having a specific wavelength or wavelengths in the range of 180nm to 270nm, which will simultaneously deactivate / destroy a majority of the viruses, bacteria and fungi carried within the airflow through the system. Clause 3. A system according to Clause 1 and optionally Clause 2 where the treatment process includes an initial application of ozone with air or gas containing separately generated ozone, which is injected into the airflow prior to electrostatic precipitation to aid the inactivation / destruction of the pathogens. Clause 4. A system according to Clause 3 where baffle plates are installed after the injection points ozone for ozone, or air or gas containing separately generated ozone, to ensure effective mixing / distribution of the ozone throughout the airflow and hence, improve the inactivation / destruction of airborne pathogens in the sequence of treatment processes. Clause 5. A system according to Clauses 1, 2 or 3 and 4 where water is atomised into the airflow prior to electrostatic precipitation to improve the performance of the electrostatic precipitation process for the removal of airborne pathogens and particulates from the airflow. Clause 6. A system according to Clauses 1, 2 or 3 and 4 where an aqueous solution of an oxidising agent, including, but not limited to, solutions of ozone, hydrogen peroxide, sodium or potassium persulphate, hypochlorous acid, sodium hypochlorite, or other biocidal chemical is sprayed or preferably atomised into the airflow using electrospray, ultrasonic nozzles or other atomising technology prior to electrostatic precipitation to improve the inactivation / destruction of airborne pathogens including those pathogens that may remain after treatment with ultraviolet light, and also to improve the performance of the electrostatic precipitation process for the removal of airborne pathogens and particulates from the airflow. Clause 7. A system according to any of Clauses 1, 2 or 3, 4 and 5 or 6 where the electrostatic precipitator contains two or more stages of electrostatic precipitation. Clause 8. A system according to Clause 7 where the particulate collection electrodes in the electrostatic precipitator have pneumatically / electrically driven vibrators attached, which are operated periodically to shake adhering particulates into a collection hopper / chamber. Clause 9. A system according to Clause 7 where the particulate collection electrodes in one or more stages of the electrostatic precipitator have nozzles installed vertically above them in a suitable arrangement, such that when water or aqueous solution of an oxidising agent and / or biocide is introduced above the electrodes to remove collected / adhering pathogens and particulates, either periodically or continuously wetting the collection electrodes, this is then collected beneath the electrodes, filtered using ceramic media or other treatment technologies to remove dead pathogens and particulates and then recirculated through the nozzles. Clause 10. A system according to Clause 7 where the particulate collection electrodes in one or more stages of the electrostatic precipitator are cooled to aid the condensation and coalescence of the atomised water, or aqueous solution of oxidising agent or other biocidal chemical, which is then collected beneath the electrodes, filtered using ceramic media or other treatment technologies to remove dead pathogens and particulates and then recirculated through the atomiser. Clause 11. A system according to Clause 7 where the particulate collection electrodes in one or more stages of the electrostatic precipitator are porous, such that water or a solution of an oxidising agent and / or biocide in water is introduced inside the electrodes and exits through their porous surfaces and flows downwards carrying collected pathogens and particulates, this is then collected beneath the electrodes, filtered using ceramic media or other treatment technologies to remove dead pathogens and particulates and then recirculated through the porous electrodes. Clause 12. A system according to Clause 7 where the particulate collection electrodes in one or more stages of the electrostatic precipitator are designed such there is a continuous downward flow of a thin film of water or a solution of an oxidising agent and / or biocide in water carrying collected pathogens and particulates, this is then collected beneath the electrodes, filtered using ceramic media or other treatment technologies to remove dead pathogens and particulates and then recirculated over the electrodes. Clause 13. A system according to any of Clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, and 12 where the treatment process includes an application of one or more stages ultraviolet light in the wavelength range of 250nm to 290nm to the airflow after it exits electrostatic precipitation, such that not only are pathogens remaining in the airflow after electrostatic precipitation destroyed, but removal of ozone remaining in the airflow through its transformation into oxygen gas - specific wavelengths of electromagnetic radiation present in UV-C light break open the unstable bonds in the oxygen atom triplets that comprise the ozone molecules so that they break down to oxygen are irradiated with this ultraviolet light, but ozone as might be present in the airflow exiting the electrostatic precipitation is destroyed by these particular wavelengths of ultraviolet light. Clause 14. A system according to any of Clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, and 12 where the treatment process includes an application of one or more stages ultraviolet or other light in conjunction with one or more photocatalysts to the airflow after it exits electrostatic precipitation to breakdown and remove the ozone molecules as might be present in the airflow exiting electrostatic precipitation or other treatment stage. Clause 15. A system according to any of Clauses 1,2, 3, 4, 5, 6, 7, 8, 9, 11, and 12 that includes a sensor or sensors to control and activate and / or deactivate one, or more, or all of the stages in the sequence of technologies implemented within the current invention, and / or increase / decrease periods of activation, treatment intensity and / or other operating parameters of one, or more, or all stages in the sequence of technologies implemented within the current invention. Where such sensors may amongst other measured parameters detect changes in carbon dioxide concentrations and / or temperature and or humidity within the air flow and / or room, building or facility, movement and / or numbers of individuals entering or leaving such room building or facility.

Claims

1. An air treatment system for removal of pathogens and airborne particulates, wherein the air treatment system comprises a plurality of treatment stages,wherein the air treatment system is configured to receive air for treatment drawn from within a room or other enclosed space for discharge back into the room or other enclosed space or elsewhere, or configured to receive air drawn from outside or other exterior environment and discharged into a room or other enclosed space or elsewhere,wherein the air treatment system is configured to pass the received air as an airflow through the plurality of treatment stages; and;wherein the plurality of treatment stages comprises:at least one first ultraviolet treatment stage configured to apply ultraviolet light to the airflow, at least one injection stage after the at least one first ultraviolet treatment stage, the at least one injection stage configured to introduce one or more of water, an oxidising agent and / or biocide into the airflow;at least one electrostatic precipitation stage provided after the at least one first ultraviolet treatment stage and configured to perform electrostatic precipitation on the airflow, wherein each electrostatic precipitation stage comprises particulate collection electrodes; andat least one second ultraviolet treatment stage configured to apply ultraviolet light to the airflow.

2. The air treatment system of Claim 1, wherein the at least one ultraviolet treatment stages comprises:wherein the ultraviolet light applied by the at least one first ultraviolet treatment stage has a wavelength range of 170nm to 200nm or a wavelength range of 180nm to 270nm; and / orwherein the ultraviolet light applied by the at least one second ultraviolet treatment stage has a wavelength or wavelengths in the range of 180nm to 270nm.

3. The air treatment system of claim 1 or claim 2, wherein the at least one injection stage is configured to atomise the water introduced into the airflow.

4. The air treatment system according to claim 1, wherein the air treatment system is configured to electrolyse solutions of sodium or potassium sulphate in water using boron-doped diamond or mixed metal electrodes to form a solution of peroxygen compounds selected from: hydrogen peroxide, sodium or potassium persulphate, the solution of peroxygen compounds being the oxidising agent and the biocide.

5. The air treatment system according to claim 3 or claim 4, wherein the at least one injection stage is configured to perform atomisation using electrospray or ultrasonic nozzles.

6. The air treatment system of any preceding claim, wherein the oxidising agent includes one or more of ozone, hydrogen peroxide, sodium or potassium persulphate, hypochlorous acid, sodium hypochlorite.

7. The air treatment system according to any preceding Claim, further comprising baffle platesare installed after the at least one injection stage.

8. The air treatment system according to any preceding claim, wherein the at least one electrostatic precipitation stage comprises at least two electrostatic precipitation stages.

9. The air treatment system according to any preceding Claim where the particulate collection electrodes in each electrostatic precipitation stage comprises pneumatically / electrically driven vibrators attached to the particulate collection electrodes, the vibrators configured to be operated periodically to shake adhering particulates into a collection hopper / chamber.

10. The air treatment system according to any one of Claims 1 - 8, where one or more of the at least one electrostatic precipitator stage each further comprise nozzles installed above the particulate collection electrodes of the electrostatic precipitation stage, the nozzles configured to inject water, an aqueous solution of an oxidising agent, and / or biocide in water to periodically or continuously wet the particulate collection electrodes,wherein the one or more electrostatic precipitator stage of the at least one electrostatic precipitator stage is configured to collect beneath the particulate collection electrodes the water, aqueous solution of an oxidising agent, and / or biocide in water injected by the nozzles, and to recirculate the collected water, aqueous solution of an oxidising agent, and / or biocide in water through the nozzles, wherein the electrostatic precipitator further comprises filtering elements configured to filter the collected water, aqueous solution of an oxidising agent, and / or biocide in water.

11. The air treatment system according to Claim 1, where the particulate collection electrodes in one or more of the at least one electrostatic precipitator stage are configured to be cooled such that water, oxidising agent and / or biocide passing over the particulate collection electrode condenses,wherein the one or more electrostatic precipitator stage of the at least one electrostatic precipitator stage is configured to collect beneath the electrodes the water, the oxidising agent, and / or biocide condensed on the particulate collection electrodes, and recirculate the collected water, oxidising agent, and / or biocide through the at least one injection stage, wherein the electrostatic precipitator further comprises filtering elements configured to filter the collected water, oxidising agent, and / or biocide.

12. The air treatment system according to any one of Claims 1 - 8, where the particulate collection electrodes in the one or more stages of the at least one electrostatic precipitator stage are porous collection electrodes,wherein the one or more stages of the at least one electrostatic precipitator stage is configured to:introduce water, an aqueous solution of an oxidising agent and / or biocide in water inside the electrodes such that the water, aqueous solution of an oxidising agent and / or biocide in water exits through the porous surfaces of the porous collection electrodes and flows downwards carrying collected pathogens and particulates,collect the water, aqueous solution of an oxidising agent and / or biocide in water introduced inside the electrodes beneath the electrodes, andrecirculate the collected water, aqueous solution of an oxidising agent and / or biocide in water through the porous electrodes, wherein the electrostatic precipitator further comprises filtering elements configured to filter, prior to recirculation, the collected water, aqueous solution of an oxidising agent and / or biocide in water.

13. A system according to any one of Claim 10 to 12, where the one or more of the least one electrostatic precipitator stage are configured to introduce the water, aqueous solution of an oxidising agent and / or biocide in water such that the there is a continuous downward flow of a thin film of water, aqueous solution of an oxidising agent and / or biocide in water.

14. The air treatment system according to any preceding claim, where the air treatment system is configured to introduce one or more photocatalysts into the airflow after the airflow exits the at least one electrostatic precipitation stage.

15. The air treatment system according to any preceding claim, the air treatment system further comprising a sensor or sensors configured to:measure parameters comprising changes in carbon dioxide concentrations, changes in temperature and / or changes in humidity within the airflow, and / ormeasure movement of or numbers of individuals entering or leaving the enclosed environment;wherein the sensor or sensors are further configured to control and / or activate / deactivate at least one of the plurality of treatment stages.

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