Technical Field

[0001] The present invention relates to methods and apparatus for decomposing chemical species in a contaminated fluid and, in particular, to methods and apparatus for decomposing persistent chemical species such as persistent organic pollutants (POPs) or persistent, bioaccumulative and toxic substances (PBTs).

Background Art

[0002] Many chemical species will not degrade under typical environmental conditions because they are resistant to environmental degradation though chemical, biological and photolytic processes. To take but one example, the chemical species collectively referred to as polyfluoroalkyl substances (PFASs), which includes perfluorooctane sulfonate (PFOS), perfluoro-octanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS) were, for many years, used to make an aqueous foam used as a fire suppressant at airfields worldwide. These compounds are, however, persistent toxins, with some being carcinogens that appear to persist indefinitely in the environment. Many sites within Australia, and around the world, are now heavily contaminated with PFAS and, in some locations, this contamination has entered water supplies.

[0003] It is difficult to decompose such chemical species without subjecting them to extremely harsh conditions, which may not be practically obtainable due to factors such as the volume of the contaminated material requiring treatment. For example, while chemical species such as PFAS might be decomposed by heating to elevated temperatures, the massive amount of material (e.g. contaminated earth) that would need to be heated up to that temperature in order to decompose the PFAS makes such a technique completely impractical. Such techniques also become redundant once the contaminate enters the water table. Summary of Invention

[0004] In a first aspect, the present invention provides a method for decomposing chemical species in a contaminated fluid. The method comprises:

atomising a liquid stream and delivering atomised droplets into an upper portion of a reaction chamber having a pressurised atmosphere comprising a gaseous reactive species, the contaminated fluid being delivered into the reaction chamber with the liquid stream or with the gaseous reactive species;

causing a vortex within the reaction chamber, whereby the atomised droplets spiral downwardly, with larger sized atomised droplets tending to move towards sidewalls of the reaction chamber; and

collecting atomised droplets which land at a centre of a lower portion of the reaction chamber, the collected droplets providing a treated liquid comprising decomposed chemical species.

[0005] The inventor has discovered that even very persistent chemical species can be decomposed when exposed to a pressurised atmosphere containing gaseous reactive species. The inventor discovered that pressurised conditions favour the mass transfer of the gaseous reactive species into the atomised droplets, whereupon the reactive species can chemically interact with and decompose the chemical species. The vortex caused within the reaction chamber ensures that the atomised droplets are thoroughly mixed with the gaseous reactive species and remain entrained in the reactive species-rich atmosphere for longer than might otherwise be the case (i.e. in the absence of a vortex). As only the relatively smaller atomised droplets (which have a much higher surface area to volume ratio than the relatively larger atomised droplets and which are more likely to have spent a longer time suspended in the atmosphere) will tend to land at the centre of the lower portion of the chamber, the chemical species carried in these particles will be much more likely to have been more completely exposed to the reactive species and hence decomposed.

[0006] In some embodiments, the method may further comprise causing the gaseous reactive species to flow upwardly within the reaction chamber. Such an upwards flow of the gaseous reactive species would act to further delay the rate at which the atomised droplets fall within the chamber and hence even further increase the likelihood of interactions between the chemical species and reactive species.

[0007] In some embodiments, a continuous flow of the gaseous reactive species may be delivered to the lower portion of the reaction chamber. In such embodiments, the concentration of the reactive gaseous species, and hence the reactivity of the atmosphere within the reaction chamber would not tend to decrease over time, with reacted reactive species continually being replenished with fresh reactive gaseous species in order to ensure that substantially all of the chemical species delivered into the reaction chamber are ultimately decomposed.

[0008] In some embodiments, the contaminated fluid may be delivered into the reaction chamber either entrained with or as the gaseous reactive species (e.g. when the contaminated fluid is a gas). Alternatively, the contaminated fluid may be mixed into the liquid stream before the liquid stream is atomised (e.g. when the contaminated fluid is a liquid).

[0009] In some embodiments, atomised droplets which are not collected (i.e. as the treated liquid) may land in a reactive liquid reservoir at a lowermost portion of the reaction chamber. Advantageously, in such embodiments, the liquid stream for atomising may comprise reactive liquid drawn from the reservoir. Thus, a recycle loop can be provided to reintroduce un- decomposed (or partially decomposed) chemical species back into the reaction chamber in order for substantially all of the chemical species introduced into the reaction chamber to eventually be decomposed.

[0010] In some embodiments, temperature, volume, pH and ORP of the reactive liquid in the reservoir may be independently adjustable, both before and during operation of the method of the present invention. These parameters may be adjusted before any atomised droplets are delivered into the reaction chamber such that performance of the present invention does not substantially affect the temperature, volume, pH and ORP of the reservoir during operation. In some embodiments, the method may further comprise monitoring and maintaining the temperature, volume, pH and/or ORP of the reactive liquid in the reservoir during operation.

[0011] In embodiments of the method of the present invention including a reservoir, the gaseous reactive species may, for example, be delivered into the reaction chamber by diffusing into the reservoir (e.g. using one or more Venturis, if a smaller bubble size is desired).

[0012] The inventor has found that a pressure of between about 1 and about 2.5 atmospheres in the reaction chamber and atomised droplets having a size of between about 30μιη and 50μιη result in an acceptable operation of the method of the present invention.

[0013] In a second aspect, the present invention provides an apparatus for decomposing chemical species in a contaminated fluid. The apparatus comprises:

a pressurisable reaction chamber configured to contain an atmosphere comprising a gaseous reactive species, the reaction chamber comprising: one or more atomisers, located at an upper portion of the reaction chamber and configured to atomise a liquid stream for delivery into the chamber; and a treated liquid collector configured to collect atomised droplets which land at a centre of a lower portion of the reaction chamber,

wherein the contaminated fluid is deliverable into the reaction chamber with the liquid stream or with the gaseous reactive species, and

wherein the reaction chamber is configured to cause a vortex, whereby the atomised droplets spiral downwardly in the reaction chamber, with larger sized atomised droplets tending to move towards sidewalls of the reaction chamber.

[0014] In some embodiments, the apparatus may further comprise a gaseous reactive species inlet, located at the lower portion of the reaction chamber and configured to deliver the gaseous reactive species into the reaction chamber.

[0015] In some embodiments, the apparatus may further comprise a gaseous reactive species outlet, located at an uppermost portion of the reaction chamber and configured to receive a flow of the gaseous reactive species.

[0016] In some embodiments, the contaminated fluid may be delivered into the reaction chamber either entrained with or as the gaseous reactive species. Alternatively, the contaminated fluid may be mixed into the liquid stream before the liquid stream is atomised.

[0017] In some embodiments, a lowermost portion of the reaction chamber may define a reservoir for holding a reactive liquid, with atomised droplets that do not land at the centre of the lower portion of the reaction chamber landing instead in the reservoir. In such

embodiments, the apparatus may also comprise a conduit between the reservoir and the one or more atomisers, whereby reactive liquid drawn from the reservoir provides at least a portion of the liquid stream (i.e. in order to achieve the recycling described herein).

[0018] In embodiments in which the apparatus comprises a reservoir, the gaseous reactive species may, for example, be delivered into the reaction chamber via the reservoir (e.g. using one or more Venturis).

[0019] In some embodiments, the one or more atomisers may be arranged to laterally spray the atomised droplets into the reaction chamber, thereby contributing to the formation of the vortex in an uppermost portion of the reaction chamber. The one or more atomises may, for example, comprise four atomisers evenly spaced around the reaction chamber. The atomisers may, for example, be provided in the form of misters. [0020] In some embodiments, the treated liquid collector may comprise a dish onto which the atomised droplets can fall. The treated liquid collector may further comprise an outlet conduit which comprises a return loop that extends upwardly to substantially the same height as the reaction chamber, whereby a hydraulic head within the outlet conduit is provided that substantially matches the pressure within the reaction chamber.

[0021] In some embodiments, the reaction chamber may further comprise members positioned to promote (e.g. increase the strength of) the vortex. In some embodiments, the reaction chamber may be substantially cylindrical in shape (which would also help to maintain a vortex therein).

[0022] In some embodiments, the apparatus may further comprise a secondary chamber that is in fluid communication with the reservoir at the lowermost portion of the reaction chamber, the secondary chamber being configured to provide a hydrostatic head which pressurises the reaction chamber.

[0023] The secondary chamber may also provide additional functions. For example, in some embodiments, the apparatus may further comprise a gaseous reactive species conduit which delivers gaseous reactive species that have exited the reaction chamber into a lower portion of the secondary chamber. As will be described in further detail below, in some embodiments, the secondary chamber can also be configured to collect a foam fractionate which may form due to the bubbles of the gaseous reactive species flowing therethrough.

[0024] In some embodiments, the apparatus of the present invention may be used to perform the method of the present invention.

[0025] In a third aspect, the present invention provides the use of a product of the method or apparatus of the present invention in an upstream process or a downstream process.

[0026] Other aspects, features and advantages of the present invention will be described below.

Brief Description of the Drawings

[0027] The present invention will be described in further detail below with reference to the following figures, in which:

[0028] Figure 1 shows a schematic diagram of an apparatus in accordance with an embodiment of the present invention. Detailed Description of the Invention

[0029] As noted above, the present invention provides a method and an apparatus for decomposing chemical species in a contaminated fluid. The method comprises:

atomising a liquid stream and delivering atomised droplets into an upper portion of a reaction chamber having a pressurised atmosphere comprising a gaseous reactive species, the contaminated fluid being delivered into the reaction chamber with the liquid stream or with the gaseous reactive species;

causing a vortex within the reaction chamber, whereby the atomised droplets spiral downwardly, with larger sized atomised droplets tending to move towards sidewalls of the reaction chamber; and

collecting atomised droplets which land at a centre of a lower portion of the reaction chamber, the collected droplets providing a treated liquid comprising decomposed chemical species.

[0030] The apparatus comprises:

a pressurisable reaction chamber configured to contain an atmosphere comprising a gaseous reactive species, the reaction chamber comprising:

one or more atomisers, located at an upper portion of the reaction chamber and configured to atomise a liquid stream for delivery into the chamber; and a treated liquid collector configured to collect atomised droplets which land at a centre of a lower portion of the reaction chamber,

wherein the contaminated fluid is deliverable into the reaction chamber with the liquid stream or with the gaseous reactive species, and

wherein the reaction chamber is configured to cause a vortex, whereby the atomised droplets spiral downwardly in the reaction chamber, with larger sized atomised droplets tending to move towards sidewalls of the reaction chamber.

[0031] The present invention may be used to decompose any chemical species which is capable of being decomposed via a suitable reaction mechanism (described in more detail below). The invention is expected to find particular application in treating gases or liquids contaminated with such chemical species, but would also be capable of treating such species originally contained in solid materials by incorporating an appropriate pre-treatment step (e.g. by leeching the contaminate from a solid feed, for example). [0032] The present invention provides methods and apparatus for decomposing chemical species (and, in particular, persistent contaminants which are otherwise very resistant to being decomposed) in a contaminated fluid. In the context of the present invention, it is to be understood that the term "decomposing", or the like, means that the chemical species is broken down from the form in which it is delivered into the reaction chamber into a form that is subsequently processable, but not necessarily broken down into its constituent elements. It is possible that a decomposed chemical species produced in accordance with the present invention may be only partially broken-down, and especially when the partially broken-down species may provide a useful function in the present invention or in upstream/downstream processes. The conditions under which the present invention is performed can be controlled (as described herein) in order to produce such a desired outcome.

[0033] Although described herein mainly in the context of decomposing a chemical species in a contaminated fluid, it will be appreciated that the present invention could be used to

simultaneously decompose a number of chemical species in one or more contaminated fluids (noting that typical industrial fluid wastes would likely contain a number of contaminants).

[0034] The invention is expected to find particular application in decomposing persistent chemical species, which have previously not been able to be decomposed in a practical (and especially economically viable) manner. Specific examples of chemical species that could be decomposed in accordance with the present invention include the persistent PFAS class of substances described above. Other chemical species that could be decomposed in accordance with the present invention include PCBs (polychlorinated biphenyls), PAHs (polycyclic aromatic hydrocarbons), vinyl chlorides, VOCs, PFCs in general, pesticides such as DDT and DDE, as well as other emerging recalcitrant and persistent contaminants. It is within the ability of a person skilled in the art, based on the teachings herein and using only routine

experimentation, to determine whether any given chemical species could be decomposed using the present invention.

[0035] Any reaction mechanism via which such decomposition may be achieved is within the scope of the present invention, as described herein. By way of example only, suitable reaction mechanisms include mineralisation, oxidation, advanced oxidation, reduction or advanced reduction reaction mechanisms.

[0036] The reaction chamber in the present invention has a pressurised atmosphere comprising a gaseous reactive species. Any reactive species may be used in the present invention, provided that it is in gaseous form at the pressures contemplated by the present invention for the reaction chamber and capable of mass transfer into the atomised droplets. More highly reactive species would generally be preferred for decomposing more persistent chemical species, but any suitable reactive species may be used for more easily decomposable chemical species.

[0037] The gaseous reactive species may, for example, be a gaseous oxidant or a gaseous reductant, with corresponding oxidation or reduction reactions being responsible for decomposition of the chemical species. The gaseous reactive species may, in some

embodiments, be provided in an already active form or in a form which is capable of forming an oxidant or reductant upon contact with the atomised droplets.

[0038] In some embodiments, for example, the gaseous reactive species may be a gaseous species capable of forming oxidising or reducing radical species upon diffusion into the atomised droplets within the reaction chamber. For example, when the gaseous reactive species is ozone, diffusion of ozone into the atomised droplets can result in the formation of hydroxyl radicals (ΌΗ), which are very strong oxidants and which can react to decompose even the most persistent chemical species. As will be appreciated however, many other types of radicals can be formed under appropriate conditions, including: "C0 ₂ ^" , CO3 ^" , 0 ₃ , "N3, 'Nth, ^' NO2, NO3 ^" , O3 ^2" , P0 ₄ ^'2" , S0 ₂ ^'" , ^' SO3 ^" , SO4-, SO5-, Se0 ₃ ^'~ (SCN) ₂ ^'~ , Cl ₂ ^'~ , Br ₂ , h ^'~ , C10 ₂ \ Br0 ₂ \ Such radicals can be produced by reactions known in the art, for example, by irradiation with UV radiation, exposure to hydroxyl radicals or high/low pH, as well as other conditions that can be attained within the reaction chamber. A number of such conditions will be described in further detail below and, in light of the teachings contained herein, it is within the ability of a person skilled in the art to determine other conditions suitable for decomposing specific chemical species.

[0039] Without wishing to be bound by theory, the inventor believes that it is likely to be a combination of radicals that result in the highly effective decompositions of the present invention. For example, when the gaseous reactive species is ozone, diffusion of ozone into the atomised particles can result in the formation of hydroxyl radicals (ΌΗ), which can cause cascading reactions that result in the formation of other radical species, the combination of these radical species being effective to decompose the chemical species.

[0040] The gaseous reactive species may, for example, be a gaseous oxidant or a gaseous reductant. Suitable gaseous oxidants include, for example, ozone, oxygen, chlorine and nitrous oxide. Suitable gaseous reductants include ammonia, carbon dioxide and various flue gases.

[0041] The contaminated fluid is delivered into the reaction chamber either with the gaseous reactive species or with the liquid stream. Typically, a contaminated liquid would be delivered into the reaction chamber mixed with the liquid stream, and a contaminated gas would be delivered into the reaction chamber mixed with the gaseous reactive species, but this need not always be the case. Provided that the contaminated fluid is effectively delivered into the reaction chamber (i.e. in a form where it can react in accordance with the present invention), it is not essential for the contaminated fluid be in an intimate mixture with the liquid stream or gaseous reactive species. For example, co-delivery into the reaction chamber via separate conduits might be appropriate in some circumstances.

[0042] In some embodiments, contaminated fluids (the same or different) might be delivered into the reaction chamber both with the gaseous reactive species and the liquid stream.

[0043] In embodiments where the contaminated fluid is delivered into the reaction chamber with the gaseous reactive species, then the contaminated fluid may, for example, be delivered into the chamber entrained within the gaseous reactive species. That is, the contaminated fluid (e.g. gas) is mixed with the gaseous reactive species at some stage before its delivery into the reaction chamber. Typically, such mixing would occur relatively close to the chamber, and would be a turbulent mixing in order to ensure a relatively homogeneous dispersion of the gasses.

[0044] In some embodiments, the contaminated fluid may itself be the gaseous reactive species. For example, many flue gases contain significant amounts of carbon dioxide which, as described above, under appropriate conditions, can be used to produce the ^" CO2 ^" radical (a potent reductant). As flue gasses often contain contaminants which preclude them being emitted directly to the environment, however, they require treatment, with many of such treatment processes being expensive or ineffective due to the persistent nature of some of the

contaminants. One flue gas the inventor has found can be used in the present invention is that produced by smokehouses, which produce a carbon dioxide-containing gas containing significant contaminants including those typical of smoke house emissions such as

hydrocarbons, both aliphatic (e.g. methane, ethane, ethylene, acetylene, etc.) and aromatic (benzene and its derivatives, polycyclic aromatic hydrocarbons; e.g. benzo[a]pyrene, studied as a carcinogen or retene), as well as terpenes and heterocyclic compounds.

[0045] In such embodiments, once inside the pressurised reaction chamber, the flue gas would become entrained within the vortex and, via the process of mass transfer, diffuse into the atomised droplets. Under appropriate conditions, the presence of the carbon dioxide in the gas would result in the formation of (amongst other reactive species) the *C02 ^~ radical, which would react with, and subsequently decompose the other contaminants in the flue gas, ultimately resulting in a treated liquid.

[0046] In embodiments where the contaminated fluid is delivered into the reaction chamber with the liquid stream, then the contaminated fluid would typically be delivered into the chamber well mixed with the liquid stream. That is, the contaminated fluid (e.g. liquid) is mixed with the liquid stream at some stage before its delivery into the reaction chamber via the one or more atomisers. Typically, such mixing would occur relatively close to the chamber, and would be a turbulent mixing in order to ensure a relatively heterogeneous dispersion of the liquids.

[0047] The liquid stream delivered to the reaction chamber may be obtained from any source. In some embodiments, for example, a liquid stream comprising the contaminated fluid may simply be pumped from a storage location such as a tailings dam or aquifer (with a pre-filtering step, if necessary) and directly into the reaction chamber. Alternatively, a liquid stream comprising the contaminated fluid may come directly from the outlet of an industrial process which produces the chemical species for decomposition (e.g. a reverse osmosis reject stream). Alternatively, a liquid stream (that may or may not include the contaminated fluid) may be drawn from another source. As will be described below, the liquid stream may, in some embodiments, be recycled in the present invention in order to even further enhance its efficiency. It is within the ability of a person skilled in the art, based on the teachings herein and using only routine experimentation, to determine whether any given liquid stream would be appropriate for use in the present invention.

[0048] Given the relative volumes of contaminated fluid (typically a liquid) likely to be processable by the present invention, a pre-concentration step may be beneficial. In such a pre- concentration step, the contaminate would be concentrated into a smaller volume of fluid for delivery into the reaction chamber. Any suitable pre-concentration step may be used. For example, the specific embodiments of the present invention described in detail below are adapted to receive a contaminated fluid in the form of a foam fractionate obtained from the ozofractionation of a much larger volume of contaminated water.

[0049] The inventor of the invention the subject of the present application has previously discovered the ozofractionation process the subject of international patent application no.

PCT/AU2012/000924, the contents of which are incorporated herein. Ozofractionation has been found to be an extremely effective technique for removing contaminates from a liquid stream. For example, separation of PFOS from contaminated ground waters has been shown (see the Examples described below) to be above 99% using ozofractionation, with the PFOS being concentrated in the fractionated fluid stream (the concentration of PFOS in the foam fractionate reaching levels of approximately 120,00C^g/L from a source concentration of \ 0μg/L in the ground water).

[0050] Even though the contaminate has been removed from the groundwater, however, the conditions within the ozofractionation chamber are not necessarily severe enough to destroy the persistent PFOS molecules. The inventor therefore subsequently expended considerable resources in investigating methods which might be used to mineralise, oxidise, reduce or otherwise decompose persistent or recalcitrant pollutants that may be present in the foam fractionate and, in doing so, made the discovery underlying the present invention.

[0051] In embodiments where the contaminated fluid is delivered into the reaction chamber with the liquid stream, the proportion of the contaminated fluid in the liquid stream may vary, depending on factors such as how persistent to decomposition the chemical species is and the nature of the conditions inside the reaction chamber. In some circumstances (e.g. for relatively dilute liquid streams or liquid streams containing contaminants which are relatively easy to decompose), it might be appropriate to deliver the contaminated fluid into the reaction chamber undiluted. However, more typically, the contaminated fluid will be mixed with the liquid stream, with the proportion of contaminated fluid being mixed into the liquid stream typically being relatively small. For example, the proportion of contaminated fluid in the liquid stream may be less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less than 2% or less than 1% of the total volume of the liquid stream delivered to the chamber. In some embodiments, the proportion of contaminated fluid in the liquid stream may be about 30%, about 25%, about 20%, about 15%, about 10%, about 5%, about 2% or about 1% of the total volume of the liquid stream delivered to the chamber.

[0052] As described in further detail below, in some embodiments, the liquid stream may comprise or consist essentially of liquid drawn from a reservoir within the reaction chamber, with the contaminated fluid being mixed therewith shortly before its delivery into the reaction chamber.

[0053] In the present invention, only the atomised droplets which land at the centre of the lower portion of the reaction chamber are collected. As described above, only the relatively smaller atomised droplets tend to land at the centre of the lower portion of the chamber. As these droplets have a much higher surface area to volume ratio than the relatively larger atomised droplets, the chemical species carried in the collected droplets will be much more likely to have been exposed to the gaseous reactive species and hence decomposed (i.e. into their targeted chemical state). The relatively smaller atomised droplets are also more likely to have spent relatively longer entrained within the vortex than the relatively larger atomised droplets.

Atomised droplets which land elsewhere at the lower portion of the reaction chamber are not collected (but may be recycled, as described below).

[0054] The collected droplets provide a treated liquid, in which substantially all of the chemical species has been decomposed. Such a treated liquid may, in some embodiments, be

dischargeable to the environment. However, given the conditions likely to be present inside the reaction chamber (i.e. which can decompose even persistent chemical species), it is more likely that the treated liquid obtained from the reaction chamber will require further treatment before it is ready for final discharge.

[0055] In some embodiments, the treated liquid may have beneficial properties that make it useful in downstream (or upstream) processes in the overall treatment process. For example, the treated liquid may have a pH or ORP that would make it useful in preceding or subsequent process chambers for pre-treatment or subsequent treatment process. In such embodiments, the treated liquid may be useful for altering the pH or providing some chemical assistance to a preceding or subsequent treatment chamber's chemical mechanism.

[0056] In embodiments where a continual flow of gaseous reactive species flows through the reaction chamber, a gas discharge would typically also be required. Given the nature of many gaseous reactive species (e.g. ozone and chlorine), such a gas discharge would need to be carefully controlled and not simply discharged to the environment. In some embodiments, any gas discharged could be collected for appropriate destruction before venting to the atmosphere. In alternative embodiments, however, it may be beneficial to direct the gaseous emissions (which will likely contain at least some unreacted gaseous reactive species) towards preceding or subsequent processes in the overall treatment process incorporating the present invention. For example, ozone discharged from the present invention may be directed towards preceding or subsequent ozofractionation processes in a treatment process incorporating the reaction chamber of the present invention.

[0057] The present invention comprises a reaction chamber in which the reactions that cause the chemical species to be decomposed occur. The interior of the reaction chamber is configured to be pressurised and contain an atmosphere that includes a gaseous reactive species (e.g. a gaseous oxidant or reductant). The reaction chamber may have any suitable size and shape, provided that it is capable of achieving the functions described herein. Typically, the reaction chamber will be substantially cylindrically shaped (at least on the inside), in order to promote the formation of the vortex therein. Typically, the reaction chamber will be relatively tall (e.g. 10- 12m), in order to allow the atomised droplets to have an extended fall through the enriched atmosphere. In some embodiments, the reaction chamber may also include members positioned therein to increase the strength of the vortex (e.g. aerodynamic fins positioned within the chamber to assist in the creation and maintenance of the vortex).

[0058] The reaction chamber may be formed from any suitable material, bearing in mind its size and the potentially hazardous and corrosive nature of the materials that will be contained therein. In some embodiments, for example, the chamber may be formed of a plastic material such as UPVC, HDPE or isophthalic filament wound fiberglass. Alternatively, the chamber (or parts thereof) may be formed of a metallic material such as titanium. In some embodiments, the chamber may be provided in modular form, for subsequent assembly on-site.

[0059] Specific components of the reaction chamber will be described in further detail below. It will be appreciated that a number of other components (e.g. conduits, instruments for measuring conditions inside the chamber, safety features, etc.) in addition to those described below may be required in order for the reaction chamber to function. However, the necessity (or not) for such other components will be well understood by the person skilled in the art, and their

incorporation into the reaction chamber require only routine modifications or adaptations.

[0060] The reaction chamber includes one or more atomisers, located at an upper portion of the reaction chamber and configured to atomise a liquid stream (that may comprise the

contaminated fluid) for delivery into the chamber. The atomisers convert the liquid stream into atomised droplets which have a much higher (orders of magnitude higher) ratio of surface area to volume. As such, the gaseous reactive species present in the atmosphere of the reaction chamber is able to diffuse, via mass transfer, into the atomised droplets. Such diffusion into the atomised droplets is enhanced due to the elevated pressure within the reaction chamber.

[0061] Any atomisers may be used in the present invention, provided that they are capable of converting the liquid stream into very fine particles or droplets. Typically, the atomisers are provided in the form of misters, which convert the liquid stream into a fine mist. Suitable misters are, for example, commercially available under the brand P&A-BETE, sold by Spray Nozzle Engineering. The atomisers/misters may produce atomised droplets having any size, bearing in mind the rate of flow of the liquid stream into the reaction chamber. As would be appreciated, the smaller the droplet size, the higher the ratio of surface area to volume and hence the more efficient the mass transfer of the gaseous reactive species into the atomised droplet. Smaller droplets will also tend to remain suspended in the vortex for longer, thereby increasing their retention time within the reaction chamber. Droplets that are too large would fall through the reaction camber relatively quickly and not feel the effect of the vortex as much, thus reducing the likelihood of chemical species contained therein being exposed to the reactive species (both because of their relatively shorter retention time and lower surface area to volume ratio).

[0062] The inventor believes that droplets having a particle size of up to about 500μπι could be used in the present invention but that, in general, the smaller the droplet the better. In some embodiments, the atomisers may be adapted to deliver droplets having a maximum particle size of up to about 500μπι, about 400μπι, about 300μπι, about 200pm, about ΙΟΟμηι, about 80μπι, about 50μιη, about 40μιη, about 30 ιη, about 20μιη or about ΙΟμιη into the reaction chamber.

[0063] Typically, a given atomiser or mister will only be capable of delivering droplets having a relatively small range of particles sizes, for example, having an average particle size of about ΙΟμιη, about 20μιη, about 30μιη, about 40μιη or about 50μιη. In some embodiments, it may be advantageous to provide a number of different atomisers/misters in the reaction chamber, in order to deliver droplets having a wider range of particle sizes.

[0064] The inventor has found that atomised droplets having a particle size of between about 30μιη and 50μιη are of a size where enough of the gaseous reactive species can diffuse into the droplets to cause sufficient degradation of the chemical species contained therein, whilst maintaining an appropriate flow rate of the liquid stream into the reaction chamber.

[0065] Any number of atomisers may be used to deliver the liquid stream into the chamber, with the number tending to increase as the volume of liquid stream to be processed increases. In some embodiments, for example, the reaction chamber may comprise 1, 2, 3, 4, 5, 6, 7, or 8 atomisers. Typically, at least two atomisers would be used. Typically, the atomisers would be evenly spread throughout the reaction chamber. In some embodiments, for example, the atomised droplets are delivered into the upper portion of the chamber by four evenly spaced misters.

[0066] The one or more atomisers may be arranged to deliver the atomised droplets into the reaction chamber in any suitable manner. Typically, the atomisers (or misters) are arranged to laterally spray the atomised droplets into the chamber, which can help in the formation of the vortex in an uppermost portion of the chamber (i.e. by encouraging a circular motion of the falling droplets). [0067] In the present invention, the reaction chamber having an atmosphere comprising the gaseous reactive species is pressurised. As noted above, such pressurisation helps to promote the mass transfer of the gaseous reactive species into the atomised droplets. Any pressure above atmospheric pressure will help to promote such mass transfer although, as would be appreciated, increasing pressure by too large an amount would necessitate the use of more pressure resistant components and be more energy intensive to produce. In some embodiments, for example, pressures of between 1 and about 2.5 atmospheres (e.g. at a pressure of about 1.5, 2 or 2.5 atmospheres) in the reaction chamber are sufficient.

[0068] The reaction chamber may be pressurised using any suitable technique. In some embodiments, for example, a pump may be used to pressurise the reaction chamber. In alternative embodiments (some of which are described in further detail below), a head of water in a secondary chamber may be used to pressurise the reaction chamber.

[0069] In the present invention, a vortex is caused within the reaction chamber. The vortex causes the atomised droplets to spiral downwardly from the upper to the lower portions of the reaction chamber, with larger sized atomised droplets tending to move towards the sidewalls of the reaction chamber. Ideally, the vortex should be maintained throughout most of the height of the reaction chamber, although it may be sufficient in some embodiments for the vortex to be concentrated in the upper portion of the chamber. Indeed, causing too strong a vortex at the lower portion of the reaction chamber may hinder the collection of the fine droplets which tend to contain the decomposed chemical species.

[0070] Any method may be used to cause the vortex within the reaction chamber. For example, as noted above, the manner in which the atomised droplets are delivered into the reaction chamber can form the vortex at the upper portion of the chamber. Additional misters (e.g. spraying liquid drawn from the reservoir, in relevant embodiments) may be provided, if necessary, at lower portions of the chamber in order to maintain the vortex throughout the height of the chamber. As also noted above, in some embodiments, the shape of the reaction chamber may be conducive to the formation and maintenance of a vortex therein. The reaction chamber may also further comprise members such as aerodynamic fins positioned therein in order to assist in the creation of, maintenance of and/or to even increase the strength of the vortex.

[0071] The present invention also involves collecting the atomised droplets which land at the centre of the lower portion of the reaction chamber. As described above, the vortex within the reaction chamber causes the larger sized atomised droplets to tend to move towards the sidewalls of the reaction chamber as the atomised droplets spiral downwardly, with only the smaller sized atomised droplets tending to land at the centre of the lower portion of the reaction chamber.

[0072] As the smaller droplets have a higher surface area to volume ratio than the larger droplets, more of the gaseous reactive species would tend to have diffused into the smaller droplets and hence the chemical species therein be more likely to have reacted with the reactive species and hence been decomposed. Smaller droplets are also more likely to have spent longer suspended in the gaseous atmosphere than the larger droplets, even further increasing the likelihood of substantial degradation of the chemical species.

[0073] The larger sized droplets which contact the sidewalls of the reaction chamber tend to run down the sidewalls until they reach the bottom of the reaction chamber which may, in some embodiments and as described in further detail below, contain a reservoir. Even if the chamber does not contain a reservoir, however, the un-collected (i.e. containing the larger sized droplets) liquid at the bottom of the reaction chamber can be separately collected, either for further treatment elsewhere or for recycling back into the liquid stream. In some embodiments, the lower portion of the sidewalls of the reaction chamber may be washed down with a liquid in order to encourage the flow of the larger droplets down the sidewalls.

[0074] Any suitable technique may be used to collect the smaller droplets which land at the centre of the lower portion of the reaction chamber. In the apparatus of the present invention, the reaction chamber comprises a treated liquid collector configured to collect the atomised droplets which land at the centre of the lower portion of the reaction chamber. In one embodiment, for example, a dish onto which the smaller atomised droplets can fall may be provided at the centre of the lower portion of the chamber, with the so-collected droplets providing the treated liquid for removal from the reaction chamber using any suitable technique (some of which will be described below in the context of specific embodiments).

[0075] The present invention may be performed in a batch mode, where all of the gaseous reactive species necessary to decompose a specific amount of the relevant chemical species is provided within the reaction chamber (e.g. the reaction chamber is "pre-charged"). Typically, however, the present invention would be performed in a more continuous operation, requiring the delivery of additional gaseous reactive species to the reaction chamber during its performance. Typically, a continuous flow of the gaseous reactive species would be delivered to the lower portion of the chamber in order to charge the chamber with fresh (i.e. unreacted) reactive species. The rate of supply of the gaseous reactive species may, in some embodiments, be substantially matched to the rate of supply of the contaminated fluid (i.e. to use a minimum amount of the gaseous reactive species). In practice, however, given that such may be difficult to continuously measure and that the aim of the invention is to decompose substantially all of the contaminate, it may be preferable to ensure than an excess of gaseous reactive species is always present within the reaction chamber. Indeed, such an excess would ensure a more efficient mass transfer of the gaseous reactive species into the atomised droplets. Further, as described above, any gaseous reactive species which is vented from the reaction chamber can be beneficially recycled, either for reuse in the present invention or for use in related processes.

[0076] The method of the present invention typically further comprises causing the gaseous reactive species to flow upwardly within the reaction chamber. Such a flow of gaseous reactive species is counter to the downwards spiralling movement of the atomised droplets within the reaction chamber, and can thus help to increase the retention time of the droplets within the chamber. In such embodiments, the apparatus of the present invention may further comprise a gaseous reactive species inlet, located at the lower portion of the reaction chamber and configured to deliver the gaseous reactive species into the reaction chamber. Typically, in such embodiments, the apparatus would further comprise a gaseous reactive species outlet, located at an uppermost portion of the reaction chamber and configured to receive a flow of the gaseous reactive species, in order to provide a nett upward flow of gas through the reaction chamber.

[0077] As would be appreciated, in embodiments comprising a gaseous reactive species outlet, the flow of gas therethrough will need to be controlled in order to maintain the pressure inside the reaction chamber. In some embodiments, a secondary chamber (described below) may provide this function. In alternative embodiments, pressure relief valves may be used to enable the gaseous reactive species to flow upwardly through the reaction chamber and exit therefrom, but whilst maintaining a pressurised atmosphere.

[0078] In the apparatus of the present invention, a lowermost portion of the reaction chamber may define a reservoir for holding a reactive liquid, with atomised droplets that do not land at the centre of the lower portion of the reaction chamber landing in the reservoir. Thus, the reactive liquid in the reservoir is continually replenished by the flow of larger droplets down the sidewalls of the reaction chamber and by the atomised droplets which did not land at the centre of the lower portion of the reaction chamber.

[0079] The reactive liquid in the reservoir may be added to the reaction chamber before the process is started, or may be produced during the process. Typically, the reactive liquid in the reservoir is added before the process is started, with its reactive properties being determined based on factors such as the nature of the chemical species to be decomposed and the liquid stream. The primary properties of the reactive liquid which may be controlled in order to influence the reaction conditions inside the reaction chamber are its volume, temperature, pH and ORP (oxidation-reduction potential). As such, the temperature, volume and pH and ORP of the reactive liquid in the reservoir are typically independently adjustable (both before and during operation of the present invention).

[0080] The apparatus of the present invention may also include sensors for measuring the values of these parameters, as well as means for adjusting these properties during operation. For example, the apparatus of the present invention may further comprise a heat exchanger in contact with the reservoir for heating or cooling the reactive liquid in the reservoir as necessary. The apparatus may further comprise conduits via which acids or alkalis can be introduced into the reactive liquid, in order to decrease or increase its pH, respectively.

[0081] Typically, the reactive liquid would be heated in order to increase the rate at which chemical reactions occur within the chamber. In some embodiments, however, such reactions may be exothermic, and cooling be required in order to prevent the chamber from becoming overheated.

[0082] The pH of the reactive liquid may be (moderately or strongly) acidic or alkaline, depending on the nature of the chemical species to be decomposed, the liquid stream, gaseous reactive species, the reaction mechanism being targeted by the contaminate speciation, etc. The selected pH may be alkaline and in the range of from about 8 to 14, for example, about 9.5 - 14, or acidic and in the range of from about 1 - 6, for example, about 2 - 4.

[0083] The ORP of the reactive liquid may be adjusted to anywhere between about 50 to about 1500 mV (e.g. between about 100 to about 1300 mV between about 200 to about 1000 mV or between about 400 to about 900 mV), and may be maintained during operation of the present invention by techniques including diffusing the reactive gaseous species through the reservoir (as described herein), and irradiating the reactive liquid from the reservoir with UV light, etc. (e.g. during its recycling, as described herein).

[0084] The reservoir should ideally be relatively shallow and be a maximum of approximately 15% of the total volume of the reaction chamber in order to provide the greatest possible distance for the atomised particles to fall through the reactive atmosphere. The inventor has found that (using an appropriately prepared reactive liquid) such a volume is sufficient for the reservoir to provide effective pH buffering and oxidative/reductive potential during operation of the present invention. [0085] In embodiments in which the reaction chamber includes the reservoir, the treated liquid collector for collecting the atomised droplets which land at the centre of the reaction chamber (e.g. the dish described herein) must be positioned above the level of the reactive liquid in the reaction chamber in order to prevent the reactive liquid (which may comprise un-decomposed chemical species) from potentially contaminating the treated liquid.

[0086] The reservoir also provides a volume of liquid into which the gaseous reactive species can be delivered (e.g. by being drawn into by one or more venturi). Thus, in some

embodiments, the gaseous reactive species is delivered into the chamber by diffusing into the reservoir (e.g. using one or more Venturis). The relative shallowness of the reservoir would allow a rapid movement of the gaseous reactive species (e.g. ozone bubbles) through the reactive liquid, allowing the atmosphere above the reservoir in the reaction chamber to be enriched with the gaseous reactive species. Some of the gaseous reactive species may, however, diffuse into the reactive liquid, which, as noted above, may help to maintain its reactive properties (especially its ORP) over time.

[0087] In some embodiments of the present invention, the liquid stream (which may comprise the contaminated fluid) is delivered (in the form of atomised particles) into an upper portion of the reaction chamber. As described above, the liquid stream may be provided in any suitable form and may comprise or consist essentially of reactive liquid drawn from the reservoir. In such embodiments, a recycling of the reactive liquid, which includes the atomised droplets which did not land at the centre of the reaction chamber, back into the upper portion of the reaction chamber is achieved. In embodiments where the liquid stream consists essentially of reactive liquid drawn from the reservoir, an effectively closed loop can be provided, with the only additional fluid added to the reaction chamber being the contaminated fluid. In such embodiments, the treated liquid collected from the reaction chamber may substantially balance the additional volume of contaminated fluid delivered into the reaction chamber, such that there is substantially no nett increase in the volume of liquid within the chamber.

[0088] The contaminated fluid may, in embodiments where it is delivered into the reaction chamber with the liquid stream, be mixed into the reactive liquid drawn from the reservoir at any convenient time before the liquid stream is atomised. Typically, the contaminated fluid is mixed into the reactive liquid immediately before the liquid stream is atomised. Typically, the contaminated fluid is turbulently mixed into the reactive liquid, in order to ensure that adequate mixing occurs pre-atomisation. [0089] The apparatus of the present invention may be provided with appropriate components to achieve such recycling of the reactive liquid from the reservoir to the atomisers. The apparatus may, for example, comprise a conduit between the reservoir and the atomisers, whereby reactive liquid drawn from the reservoir is mixable with the contaminated fluid to provide the liquid stream.

[0090] As noted above, when delivered into the reaction chamber with the liquid stream, the contaminated fluid typically comprises only a small proportion of the liquid stream, with the volume of the contaminated fluid mixed into the liquid drawn from the reservoir preferably being approximately the same as a volume of the collected treated liquid.

[0091] The invention may also utilise the reactive liquid in the reservoir to wash down the lower portions of the sidewalls of the reaction chamber. Such a wash down would accelerate the return of the larger atomised droplets which the vortex has forced to the sidewalls of the reaction chamber back to the lower portion of the chamber (i.e. and into the reservoir). The reaction chamber may, for example, further comprise one or more conduits configured to draw the reactive liquid from the reservoir for spraying onto the sidewalls of the chamber at an upper portion thereof.

[0092] As described above, the apparatus of the present invention may further comprise a secondary chamber that is in fluid communication with the reservoir at the lowermost portion of the reaction chamber (typically the reservoir). The secondary chamber is configured to provide a hydrostatic head which can pressurise the reaction chamber, and may, in some embodiments, provide the additional functionality described below. Typically, the second chamber has a height greater than that of the reaction chamber so that it can impart a pressure greater than atmospheric pressure to the reaction chamber. It is envisaged that a secondary chamber up to about 2-3 times taller than the reaction chamber could be utilised to apply a hydrostatic head of up to about 2.5 atmospheres to the reaction chamber.

[0093] In operation of some embodiments of the present invention, the reaction and secondary chambers are initially in equilibrium and are joined via a conduit at a lower portion thereof. The conduit is located below the level of the reactive liquid in the reservoir, such that the reactive liquid is present (at the same level) in both (unpressurised) chambers. Once the gaseous reactive species is introduced into the reaction chamber, however, the pressure within that chamber starts to rise, which causes the liquid level of the reaction chamber to fall and the liquid level of the secondary chamber to rise. Typically, the diameter of the secondary chamber is smaller than that of the reaction chamber, meaning that an increase of pressure within the reaction chamber causes a relatively large displacement of the reactive liquid into the secondary chamber. The combination of the introduction of gaseous reactive species into the reaction chamber and the hydrostatic head provided by the column of reactive liquid within the secondary chamber acts to pressurise the atmosphere above the reservoir in the reactive chamber. The amount of pressure depends on factors such as the relative sizes of the reaction and secondary chambers, rate of flow of gaseous reactive species, etc., and can be adjusted to best suit any particular treatment system. A pressure of up to about 2.5 atmospheres (i.e. over double atmospheric pressure) may be readily achieved using such a configuration.

[0094] In some embodiments, the apparatus of the present invention may further comprise a gaseous reactive species conduit which delivers gaseous reactive species that have exited the reaction chamber (e.g. from ducting at the top of the reaction chamber, thus causing the nett gaseous flow upwards in the main reaction chamber described above) into a lower portion of the secondary chamber. Typically, the outlet of the gaseous reactive species conduit would be positioned such that it is at substantially the same height as the reservoir depth in the reaction chamber (as this will allow gas to build up pressure within the reaction chamber as the fluid level within the secondary chamber increases as the pressure builds within the reaction chamber).

[0095] In some embodiments, the secondary chamber may also be configured to perform a foam fractionation in order to remove at least some of the contaminants which may be present in the reactive liquid. In such embodiments, the outlet of the gaseous oxidant conduit may be arranged in the secondary column such that the escaping gas is diffused via small apertures such that bubbles having as small a size as practical are formed and assist in creating a stable bubble column in the secondary chamber. The secondary chamber may further comprise a foam fractionator located at an upper portion of the secondary chamber, the foam fractionator being configured to collect any foam fractionate which forms in the secondary chamber. Thus, the ascending bubbles in the secondary chamber may create fractions, with the fractionation head installed such that any formed fractionates can be collected and separated in the manner described previously by the present inventor in international (PCT) patent application no.

PCT/AU2012/000924. Fractionates thus obtained could be directed as appropriate, for example, to an appropriate preceding or subsequent treatment process. For example, the apparatus of the present invention may, in some embodiments, further comprise a conduit for directing the foam fractionate to a further treatment process.

[0096] In some embodiments, a nominal flow of liquid close to the top of the secondary chamber may be provided in order to create a cross current flow in the secondary chamber against which the ascending bubbles can flow and thereby extend their retention time within the secondary chamber and potentially improve the foam fractionate separation.

[0097] Gaseous emissions from the apparatus in such embodiments are via the top of the secondary chamber (e.g. via the fractionation head). Thus, in some embodiments, the second chamber may further comprise a gaseous reactive species vent located at an upper portion thereof. The gaseous reactive species vent may, for example, comprise a conduit that is configured to recycle the gaseous reactive species, preferably for beneficial use elsewhere in the plant.

[0098] As the reaction chamber is pressurised, appropriate components would be required in order to collect the atomised droplets which land at the centre of the lower portion of the reaction chamber (i.e. those likely to contain decomposed chemical species). In some embodiments, for example, the treated liquid collector may further comprise an outlet conduit which comprises a return loop which extends upwardly to substantially the same height as the reaction chamber. A hydraulic head within the outlet conduit is thereby provided which substantially matches the pressure within the reaction chamber. As would be appreciated, this outlet head will counter any tendency for the treated liquid within the pressurised reaction chamber to be forced out from the chamber under pressure, whilst still allowing a flow of the produced treated liquid to flow out from the reaction chamber.

[0099] The apparatus of the present invention may include additional components where necessary, some of which will be described below.

[0100] In some embodiments, a filter may be provided to filter the liquid stream before it reaches the atomiser(s). Such a filter would help to prevent blockages of the atomiser(s) in the event of precipitate formation or other particulate materials entering the liquid stream.

[0101] In some embodiments, a source of radiation may be used to irradiate the liquid stream before it reaches the atomiser(s). Such irradiation can further increase the reactivity of the liquid stream (e.g. by increasing its ORP) before its delivery into the reaction chamber.

[0102] In some embodiments, for example, a source of UV light may be used to irradiate the liquid stream before it reaches the atomiser(s). As described herein, the UV light can favour the formation of radical species and otherwise increase the ORP of the liquid stream, increasing its reactivity inside the reaction chamber. In some embodiments, another high energy source of radiation may be used (possibly in addition to the UV light) to irradiate the liquid stream before it reaches the atomiser(s). [0103] In a specific embodiment of the present invention, a contaminated liquid, saturated with ozone at low pH (e.g. a foam fractionate collected from an ozofractionation process), is turbulently mixed into a high pressure, high pH, ozone rich liquid stream, and is then misted into a tall reaction chamber as 30-50μηι droplets. The atmosphere within the reaction chamber is pressurised and rich in ozone, which facilitates the continual mass transfer of ozone into the droplets, whereupon hydroxyl radicals and other radical species are formed. These newly- formed radicals react with chemical species contained within the droplets and ultimately destroy the entrained contaminate.

[0104] The droplets are held up in suspension in the reaction chamber for an extended time by a vortex created by the position of the misting jets within the chamber, amongst other features. The droplets eventually fall into the reservoir containing a high pH liquid at the base of the chamber, with the portion of the droplets that fall towards the centre of the reaction chamber being collected. The liquid so-collected may be suitable for immediate discharge, but is more likely to require further treatment. For example, the liquid may be transferred back to the ozofractionation chamber for reprocessing (once decomposed, the persistent contaminant will not separate into the foam fractionate of the ozofractionation process again).

[0105] The inventor's initial experiments have demonstrated a mineralisation of between 40- 60% of the PFOS exposed to the method described herein, which clearly implies that this method might also be a potential means by which many other persistent contaminates may be mineralised or otherwise decomposed.

[0106] Specific embodiments of the present invention will now be described, by way of example only. Referring to Figure 1, a schematic drawing illustrating an apparatus 10 in accordance with an embodiment of the present invention is shown. Apparatus 10 includes a reaction chamber 12 and a secondary chamber 14 (which will be described in further detail below). The reaction chamber 12 is substantially cylindrically shaped and is sufficiently tall (e.g. 10 - 12m) that the mist droplets described below will have an extended fall through the enriched atmosphere within the chamber 12. The reaction chamber 12 has an ozone inlet, provided in the form of a venturi 16, and a contaminated fluid inlet 18. An upper portion of the chamber has a number of misters 20, which are configured to spray a fine mist (e.g. having 30- 50μηι droplets) into the reaction chamber 12, as will be described in further detail below. A lower portion of the reaction chamber 12 has a reservoir 22, which contains a reactive liquid having a temperature, volume, pH and ORP appropriate for decomposing chemical species contained in the contaminated fluid. The lower portion of the reaction chamber 12 also has a treated liquid collector in the form of a funnel 24 for catching fine particles of mist that land towards the centre of the bottom of the reaction chamber 12. The upper portion of funnel 24 has a diameter that is less than that of the diameter of the chamber 12, such that liquid which falls down the side walls of the chamber 12 does not enter the funnel 24, but instead flows into the reservoir 22.

[0107] Liquid that collects in the funnel 24 can be removed from the apparatus 10 via treated liquid outlet 26. In order for the pressure inside the reaction chamber 12 to not cause the treated liquid from the funnel 24 to flow uncontrollably out of the treated liquid outlet 26, the conduit 28 that joins funnel 24 to treated liquid outlet 26 extends upwardly to substantially the same height as the reaction chamber 12. As can be seen in Figure 1, the water level 30 in conduit 28 (i.e. during operation of the apparatus 10) is just higher than the return portion of conduit 28, thus enabling a continuous flow of the treated liquid from the funnel 24 to the treated liquid outlet 26. A gas vent conduit 32 is also provided proximal to the return portion of conduit 28, via which any gas present in the treated fluid but which diffuses out upon exposure to atmospheric pressure can be vented (i.e. in the manner described below).

[0108] The secondary chamber 14 is located adjacent to the reaction chamber 12, and joined thereto via a conduit 34 such that liquid in the reservoir 22 can flow between the chambers 12 and 14. In the pressurised state shown in Figure 1, pumping ozone gas into the reaction chamber via Venturis 16 has caused a displacement of the reactive liquid from the reaction chamber 12 into the secondary chamber 14, with the water level in the secondary chamber 14 being maintained at water level 36, just below a fractionator head 38 (which will be described in further detail below), with the water level in the reaction chamber 12 being maintained at water level 37, just below the lip (not numbered) of funnel 24. The weight of the liquid in secondary chamber 14 provides a hydrostatic head that pressurises the atmosphere above the reservoir 22 in the reaction chamber 12. The amount of pressure applied to the reaction chamber 12 by the secondary chamber 14 depends on the relative depths of the chambers and the height of the secondary chamber 14 and, in the embodiment shown (where the secondary chamber 14 has a height of about 10m), a pressure of about 2 atmospheres can be achieved in the reaction chamber 12.

[0109] The reaction chamber 12 and secondary chamber 14 are also joined via conduit 40, which leads between an ozone vent 41 located at an uppermost portion of the reaction chamber 12 and an ozone diffuser 42, located towards a lower portion of the secondary chamber 14. Ozone bubbles which exit the diffuser 42 bubble upwardly through the reactive liquid in the secondary chamber 14, where they can cause the formation of a foam fractionate via the ozofractionation process described above. Secondary chamber 14 also has a foam fractionate recovery conduit 44, from which any foam fractionate that forms and is separated from the reactive liquid by the fractionator head 38, can be collected. Ozone gas exits the second chamber 14 via the ozone outlet conduit 46, which joins with the vent 32 before reaching the apparatus gas vent 48. Ozone reaching apparatus gas vent 48 can be destroyed using conventional processes or, more preferably, be redirected to an upstream or downstream process which requires a source of ozone.

[0110] The size of the chambers 12, 14 (and associated components) and properties of the reactive liquid in the reservoir 22 will depend on the design considerations relevant to a particular site and contaminated fluid to be treated. The components of the apparatus 10 are therefore shown with relative dimensions in the drawings in order to provide an overall description of the apparatus of this embodiment of the invention. In specific apparatuses, the chamber 12 may have a height of about 10- 12m and contain a proportionally small reservoir 22, with properties of the reactive liquid contained therein being manipulable to achieve the desired pH, ORP and temperature optimal for decomposing the relevant chemical species. Typically the selected pH will be alkaline and in the range of pH from 9.5 - 14, but the selected pH may vary depending on the reaction mechanism being targeted by the contaminate speciation.

[0111] The reservoir 22 should be no more than approximately 15% of the total volume of the reaction chamber 12, sufficient for it to provide significant pH buffering and oxidative potential, even when mixed with the contaminated fluid, as described below. Additionally the reservoir 22 provides a volume of fluid that ozone can be drawn into by venturi 16. The reservoir 22 should be relatively shallow compared to the height of the overall reaction chamber 12. The shallowness of the reservoir 22 allows for rapid movement of the ozone bubbles therethrough post-injection, allowing the atmosphere above the reservoir 22 in the reaction chamber 12 to become enriched with ozone (i.e. the reservoir 22 should not be of sufficient depth to allow efficient mass transfer of ozone into the bath from the bubbles drawn by venturi 16).

[0112] The only gaseous outlet within the reaction chamber 12 is via the ozone vent 41 at the top of the chamber. This allows for a net gaseous flow upwards in the reaction chamber 12. The outlet 42 from the conduit 40 is in the secondary chamber 14 (which has the same height as the reaction chamber 12) and positioned such that it is at substantially the same height as the water level 37 of reservoir 22 in the reaction chamber 12. This will allow the flow of ozone into the reaction chamber 12 to build up the pressure within the chamber 12 and cause the reactive liquid level within the secondary chamber 14 to increase (i.e. to the level 36 shown in Figure 1) as the pressure builds within the reaction chamber 12. [0113] The outlet 42 into the secondary chamber 14 is arranged such that the ozone is diffused via small aperture holes in the outlet 42 with as small a bubble size as practical to assist in creating a stable bubble column within the secondary chamber 14. The fractionator head 38 can be used to collect any foam fractionate that may be formed under such conditions within the secondary column 14. The fractionation head fractionate drainage 44 should be automatic and not prone to clogging. The secondary column 14 may also be provided with a nominal flow of liquid injected proximal to the fractionator head 38 via circulation inlet 50 in order to create a cross current flow against which the ascending bubbles rise (i.e. in order to increase their retention time within the secondary column 14). Fractionates from the foam fractionate outlet 44 should be directed to an appropriate preceding or subsequent treatment process (not shown).

[0114] The majority of any gases which exit the apparatus 10 do so via the ozone outlet 46 and vent 48. Such gaseous emission may be directed towards a ventilation system that may have an ozone destruction system incorporated into the ventilation system. Alternatively, as noted above, the gaseous emissions may be directed towards preceding or subsequent ozone application methods in the process circuit that the apparatus 10 is included in.

[0115] Misting jets 20 are arranged at an upper portion of the reaction chamber 12 to provide a vortex within the chamber 12 and encourage circular motion of the falling droplets. Misting jets 20 are provided centrally within the chamber 12 in order to enhance the formation of the vortex. Although not shown, aerodynamic fins may also be positioned within the chamber 12 to assist in the creation and maintenance of the vortex, especially in its upper portions.

[0116] When the reaction chamber 12 reaches its appropriate pressure and the reactive liquid in the reservoir 22 is energised to target ORP and pH levels, the contaminate fluid may be introduced into the reaction chamber 12 via the contaminated fluid inlet 18 into a recycle conduit 52, which leads to the misting jets 20 at the top of the chamber 12. The entrained contaminate is thereby exposed suddenly to the reactive liquid before being misted into the chamber 12. A pump 54 is used to pump reactive fluid through the recycle conduit 52 from the reservoir 22, past the contaminated fluid inlet 18 and into the misters 20, thereby creating a recycle loop. A portion of the flow of liquid in the recycle conduit 52 may also be directed to the circulation inlet 50 towards the top of the secondary chamber 14 in order to provide the effect described above.

[0117] A UV energiser in the form of a UV lamp 56 may be incorporated into the apparatus 10 in order to provide a HV energy source that may even further energise the liquid in the recycle conduit 52 (including the recently-entrained contaminated fluid), which may advantageously modify the mechanism of decomposition (e.g. by favouring radical formation, as described above).

[0118] The centrally located funnel 24 is at the bottom of reaction chamber 12 and is arranged to catch the predominate proportion of falling very small mist droplets (not shown) which, due to their small size tend to move towards the centre of the vortex created within the reaction chamber 12. Larger droplets (not shown) will tend to spin out towards the sides of the chamber 12 and thus be transported to the reservoir 22 via the walls of the chamber. The very small droplets will typically be more receptive to mass transfer of the ozone in the chamber's 12 atmosphere into the droplet and hence have a higher reactivity due to their surface area to volume ratio. These droplets are thus collected in the centrally located funnel 24 which, as can be seen, has its rim just above the pressurised reactive liquid level 37 of the reservoir 22. The outlet of the funnel 24 communicates via conduit 28, which provides a hydraulic pressure head to match that within the reaction chamber 12, to treated fluid outlet 26. Treated fluids may be directed towards preceding or subsequent process chambers for retreatment or subsequent treatment processes. For example, treated fluids may be useful for altering the pH or providing some chemical assistance to a preceding or subsequent treatment chamber's chemical mechanism, and may be utilised in this manner.

[0119] In use, the apparatus 10 is first pressurised by diffusing ozone into the reservoir 22 via venturi 16. As the gas is introduced into the reaction chamber 12, it starts to become pressurised, and the height of the reactive liquid in the reservoir 22 in chamber 12 drops whilst the height of liquid in the secondary chamber 14 increases. Once the reactive liquid reaches the appropriate height in the second chamber 14 (i.e. level 36), the pressure within the reaction chamber 12 is appropriate for the process of the present invention and a steady state is reached, with further ozone added to the reaction chamber 12 flowing upwardly within the chamber 12, out of vent 41 and into the second chamber 14 via diffuser 42.

[0120] Pump 54 can then be operated to draw a flow of the reactive liquid (the volume, temperature, pH and ORP of which has been adjusted in order to decompose the relevant chemical species) from the reservoir 22 and direct the liquid along recycle conduit 52 and to the misters 20 at the top of the reaction chamber 12. Misters 20 atomise the reactive liquid into small droplets and spray them into the reaction chamber 12 in a manner whereby a vortex is formed in the chamber 12. The droplets then spin slowly downwardly within the chamber 12, against the upward flow of ozone gas, whereupon the reactions described herein occur and the chemical species are decomposed. Larger droplets tend to spin out and make contact with the side walls of the reaction chamber 12, along which they subsequently slide downwardly and directly into the reservoir 22. In some embodiments, water jets (not shown) may spray the sides of the reaction chamber 12 in order to wash them down and speed up the return of the larger droplets to the reservoir 22. Smaller droplets tend to remain substantially centrally within the reaction chamber 12 as they fall, and therefore land in the funnel 24. As the smaller droplets are more likely to have been exposed to higher quantities of ozone and for a longer period of time, then the chemical species contained therein are more likely to have been decomposed.

[0121] Once a steady state has been achieved within the reaction chamber 12, the contaminated fluid can be introduced via the contaminated fluid inlet 18 and the recycle conduit 52 (and optionally via the UV lamp 56). The contaminated fluid may, for example, be the foam fractionate obtained from an ozofractionation process of the kind described above, which may be a highly concentrated solution of a persistent chemical species (e.g. PFOS). Exposure to the reactive liquid and the conditions within the reaction chamber 12 (possibly with a number of recycling cycles occurring before collection) decomposes the chemical species.

Examples

[0122] The method and apparatus described above was used to treat contaminated surface water taken from a fire fighting training area. Chemical analysis showed that the contaminated surface water included a number of persistent PFAS chemical species such as PFOS, PFOA and PFHxS. The contaminated water was treated using ozofractionation in order to produce a foam fractionate in which these persistent contaminates were highly concentrated (the concentration of PFOS in the foam fractionate, for example, reached levels of approximately 120,000μ /1. from a source concentration of 1 ΙΟμ /Ι _^ in the contaminated surface water). The foam fractionate from the ozofractionate process was produced at a rate of about 4L/hour, had a pH of about 4 and was saturated with ozone. This foam fractionate was the contaminated fluid for treatment in accordance with the present invention.

[0123] A reaction chamber similar to that described above with respect to Figure 1 was prepared by adding an appropriate volume of water and adjusting the PH of that water to 10 using sodium hydroxide (i.e. to produce the reactive liquid reservoir, or at least its precursor). Ozone was delivered into the reaction chamber via Venturis immersed in the reactive liquid in the manner described above and at a rate of about 26g hour, the vast majority of which diffuses through the reactive liquid. Over the course of about 10 minutes, the pressure within the reaction chamber increased to about 1.4 atmospheres. Target potential for the reactive liquid was achieved after about 30 minutes. Once energised and pressurised, valves that allow the liquid from the fluid reservoir at the bottom of the reaction chamber to distribute to the misters at the top of the reaction chamber were turned on and the system allowed to equilibrate for about 5 minutes.

[0124] Once equilibrated, the foam fractionate was introduced into the flow of reactive liquid to be sprayed out of the misters, whereupon it was turbulently mixed into the high pH ozone- saturated reactive liquid before being sprayed as a mist into the top of the chamber. Once a steady state was reached, a flow of about 4L/hour (i.e. to match the volume of the foam fractionate introduced into the reaction chamber) was drawn out of the treated liquid collector at the bottom of the reaction vessel to provide the treated liquid.

[0125] This steady state operation was maintained for the entire day. Fractions of the foam fractionate (i.e. the contaminated fluid) before its delivery into the reaction chamber as well as the treated liquid collected from the reaction chamber were sampled and analysed 4, 8 and 12 hours after the foam fractionate first started to be introduced into the reaction chamber. The results of this analysis are set out below in Table 1.

Species concentration ( g/L) in Species concentration (ug/L) in Species concentration ^ /L) in fraction one (t = 4 hours) fraction two (t = 8 hours) fraction three (t = 12 hours)

Contaminated Contaminated Contaminated

Treated liquid Treated liquid Treated liquid nuid Huid nuid

PER-FLUOROALKYL SUBSTANCES (PFAS)

PERFLUOROALKYL SULFONIC ACIDS

Perfluorobutane

sulfonic acid 5.11 0.141 4.98 0.879 4.66 0.905 (PFBS)

Perfluoropentane

sulfonic acid 6.23 0.0025 6.68 0.0296 7.22 0.0478 (PFPeS)

Perfluorohexane

sulfonic acid 45.5 0.0015 51 0.0149 48.4 0.041 (PFHxS)

Perfluoroheptane

sulfonic acid 4.68 <0.0005 4.64 <0.0005 3.61 0.0011 (PFHpS)

Perfluorooctane

sulfonic acid 123 0.0062 109 0.0091 72.2 0.0898 (PFOS)

Perfluorodecane

sulfonic acid <0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 (PFDS) PERFLUOROALKYL CARBOXYLIC ACIDS

Perfluorobutanoic

<0.1 <0.002 <0.1 <0.002 <0.1 <0.002 acid (PFBA)

Perfluoropentanoic

3.67 0.336 3.31 1.21 3.58 1.35 acid (PFPeA)

Perfluorohexanoic

21.2 0.151 20 1.06 20.2 1.18 acid (PFHxA)

Perfluoroheptanoic

2.95 <0.0005 3.37 0.0036 3.46 0.0118 acid (PFHpA)

Perfluorooctanoic

3.9 <0.0005 4.01 0.0006 3.31 <0.0005 acid (PFOA)

Perfluorononanoic

0.18 <0.0005 0.17 <0.0005 0.13 <0.0005 acid (PFNA)

Perfluorodecanoic

0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 acid (PFDA)

Perfluoroundecanoi

<0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 c acid (PFUnDA)

Perfluorododecanoi

<0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 c acid (PFDoDA)

Perfluorotridecanoi

<0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 c acid (PFTrDA)

Perfluorotetradecan

<0.05 <0.0006 <0.05 <0.0005 <0.05 <0.0005 oic acid (PFTeDA)

PERFLUOROALKYL SULFONAMIDES

Perfluorooctane

sulfonamide 0.08 <0.0005 0.07 <0.0005 0.05 <0.0005

(FOSA)

N-Methyl

perfluorooctane

<0.05 <0.001 <0.05 <0.001 <0.05 <0.001 sulfonamide

(MeFOSA)

N-Ethyl

perfluorooctane

<0.05 <0.001 <0.05 <0.001 <0.05 <0.001 sulfonamide

(EtFOSA)

N-Methyl

perfluorooctane

<0.05 <0.001 <0.05 <0.001 <0.05 <0.001 sulfonamidoethanol

(MeFOSE) N-Ethyl

perfluorooctane

<0.05 <0.001 <0.05 <0.001 <0.05 <0.001 sulfonamidoethanol

(EtFOSE)

N-Methyl

perfluorooctane

<0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 sulfonamidoacetic

acid (MeFOSAA)

N-Ethyl

perfluorooctane

<0.02 <0.0005 <0.02 <0.0005 <0.02 <0.0005 sulfonamidoacetic

acid (EtFOSAA)

(N:2) FLUOROTELOMER SULFONIC ACIDS

4:2 Fluorotelomer

sulfonic acid (4:2 0.05 <0.001 <0.05 <0.001 <0.05 <0.001 FTS)

6:2 Fluorotelomer

sulfonic acid (6:2 2.88 <0.001 3.33 <0.001 2.39 <0.001 FTS)

8:2 Fluorotelomer

sulfonic acid (8:2 0.38 <0.001 0.34 <0.001 0.2 <0.001 FTS)

10:2 Fluorotelomer

sulfonic acid (10:2 0.05 <0.001 <0.05 <0.001 <0.05 <0.001 FTS)

PFAS SUMS

Sum of PFAS 220 0.638 211 3.21 169 3.63

Sum of PFHxS and

168 0.0077 160 0.024 121 0.131 PFOS

Table 1 - Concentration of species in the contaminated fluid and treated liquid

[0126] As can be seen from the results shown above, the quantities of the various persistent chemical species in the treated liquid (where these are measurable) are up to three orders of magnitude less than that in the contaminated fluid (i.e. the foam fractionate) delivered into the reaction chamber.

[0127] As described above, the inventor has found that the method and apparatus of the present invention can be used to decompose even persistent chemical species such as PFOS. The inventor expects that the specific embodiments of the method and apparatus of the present invention described herein will be able to be adapted, based on the teachings contained herein and no more than routine trial and experimentation, in order to decompose other persistent chemical species. [0128] It will be understood to persons skilled in the art of the invention that many

modifications may be made without departing from the spirit and scope of the invention. All such modifications are intended to fall within the scope of the following claims.

[0129] It will be also understood that while the preceding description refers to specific sequences of process steps, pieces of apparatus and equipment and their configuration to perform such processes in relation to particular gas compositions, operating pressures and temperatures, and so forth, such detail is provided for illustrative purposes only and is not intended to limit the scope of the present invention in any way.

[0130] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.