A substance capture apparatus for use with a liquid reservoir

Abstract

The apparatus may be implemented upon liquid reservoirs exhibiting a risk of the release of an undesirable substance, for example PFAS. The apparatus includes at least one sheet material 2 sized to substantially cover the surface 3 of the liquid reservoir 4. This prevents / minimises the amount of untreated substance that escapes into the atmosphere. A spacer arrangement is disposed at or above the surface 3 of the liquid reservoir 4 to retain the sheet material 2 above the surface, maintaining an interstitial space therebetween. The undesirable substance is captured within the interstitial space by the sheet material 2 until it is subsequently evacuated. The evacuation is done through conduits 7 having a plurality of inlets 8 disposed thereupon that are in fluid communication with the interstitial space.

Description

[0001] A SUBSTANCE CAPTURE APPARATUS FOR USE WITH A EIQUID RESERVOIR

[0002] TECHNICAE FIELD

[0003] The present invention relates to devices / apparatus and associated methods for the control and capture of waste and / or toxic substances which rise to the surface of agitated / aerated water to form a bubbly -liquid, froth, foam and / or aerosolised compounds, including vapours. Embodiments of the present invention find application, though not exclusively, in water and wastewater treatment plants that make use of liquid reservoirs such as ponds, lagoons, lakes, dams, large open-top storage tanks, etc. This may include facilities such as sewerage treatments plants, wastewater resource recovery facilities, landfill sites, and the like. Non-limiting examples of such water and wastewater treatment plants include batch reactors such as Sequencing Batch Reactors (SBR), Membrane Batch Reactors (MBR) and Moving Bed Bio-film Reactors (MBBR).

[0004] BACKGROUND ART

[0005] Any discussion of documents, acts, materials, devices, articles or the like which has been included in this specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of this application.

[0006] It has been appreciated by the inventors that there is a risk of the release into the atmosphere and surrounding environment of undesirable substances from liquid reservoirs following a confidential Australian laboratory bench-scale test in May 2023 and a confidential USA field scale SAFF pilot test that proved the hypothesis that aerosolised PFAS could be captured by vacuum extraction. These experiments illustrated that more than 90% of select PFAS compounds may be removed from a water body through targeted aerosolisation. For example, sewerage treatment plants often feature open-topped ponds that are aerated to treat raw sewerage where activated sludge is biologically treated using aeration and a biological floc composed of bacteria and protozoa. Aeration using air (or oxygen) and microorganisms biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material (excluding highly persistent, PFAS chemistry). Another example is the use of aeration in open-top tanks and leachate ponds at landfill sites for leachate collection, to convert ammonia to nitrite and then nitrate (nitrification via a sequential batch reactor process) prior to disposal to sewer network connection. In each of these cases, the feedwater may initially have relatively low or even undetectable levels of undesirable substances (e.g. long- chain PFAS compounds, such as PFOS, PFOA, PFHxS and / or short-chain PFAS compounds such as PFPeA, PFBS, PFBA). However, the bubbles of the aeration process may collect and concentrate the undesirable substances in various forms including foams, froths and stratified liquid at and around the surface of the reservoir to unacceptable concentrations. These concentrated undesirable substances, when exposed to high energy induced and / or natural aeration sources are then susceptible to becoming air-borne as aerosols and / or vapours and being blown by the wind and thereby creating a secondary source of contamination through deposition on downwind surfaces including water surfaces overtime. Such contamination could then result in inhalation and / or dermal absorption by humans and terrestrial and / or aquatic wildlife, uptake by plants and migration to groundwater sources. The literature with respect to the fate and transport of PFAS and other amphiphilic chemistries has traditionally struggled to close out the mass balance equation for these sites. A theory is emerging that aerosolisation of these compounds may be resulting in wide scale environmental contamination issues due to uncontained contamination emanating via these sources. Given the proven and well documented clinical health impacts of these substances, it would be advantageous to avoid their release into the environment.

[0007] SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to overcome, or substantially ameliorate, one or more of the disadvantages of the prior art, or to provide a useful alternative.

[0009] According to the present invention there is provided a substance capture apparatus for use with a liquid reservoir defining a surface, the apparatus including: at least one sheet material sized to substantially cover the surface of the liquid reservoir; a spacer arrangement configured for disposition at or above the surface so as, in use, to retain the sheet material above the surface and thereby maintain an interstitial space intermediate the surface and the at least one sheet material; and a conduit having a plurality of inlets disposed thereupon such that, in use, the plurality of inlets are in fluid communication with the interstitial space.

[0010] Preferably, a downstream end of the conduit is connectable to vacuum suction equipment, whereby, in use, a vacuum generated by the vacuum suction equipment is communicated along the conduit to the plurality of inlets so as to draw the substance into an upstream end of the conduit and displace the substance along the conduit for depositing into an on-shore holding and processing system disposed at a downstream end of the conduit.

[0011] The features and advantages of the present invention will become further apparent from the following detailed description of preferred embodiments, provided by way of example only, together with the accompanying drawings.

[0012] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0013] Figure 1 is a plan view of a waste treatment plant at which an embodiment of the invention is being implemented;

[0014] Figure 2 is an isometric view of the embodiment;

[0015] Figure 3 is an isometric view of the embodiment depicting floatation elements supporting conduit;

[0016] Figure 4 is another isometric view of the embodiment depicting floatation elements supporting conduit;

[0017] Figure 5 is an isometric view of a free floating fluid recovery system;

[0018] Figure 6 is a plan view depicting the surface of a liquid reservoir partially covered by pieces of sheet material;

[0019] Figure 7 is an isometric view depicting the surface of the liquid reservoir partially covered by pieces of sheet material;

[0020] Figure 8 is an isometric view of the surface of the liquid reservoir partially covered by pieces of sheet material, with an on-shore holding and processing system depicted in the background;

[0021] Figure 9 is an isometric view of a condenser tank with a side removed to reveal internal detail and also depicting vacuum suction equipment;

[0022] Figure 10 is an isometric view of the on-shore holding and processing system with a pair of temporary holding tanks being depicted in the foreground;

[0023] Figure 11 is an overhead isometric view of an apparatus for separation of the substance from water;

[0024] Figure 12 is an isometric view depicting the partially covered liquid reservoir in the foreground and the on-shore holding and processing system in the background;

[0025] Figure 13 is a side isometric view depicting a portion of the waste treatment plant;

[0026] Figure 14 is an upper isometric view depicting a portion of the waste treatment plant;

[0027] Figure 15 is another isometric view depicting a portion of the waste treatment plant;

[0028] Figure 16 is an overhead isometric view of the partially covered liquid reservoir;

[0029] Figure 17 is an isometric view of the waste treatment plant; and

[0030] Figure 18 is a schematic cross sectional view of a conduit with inlets and having sheet material draped above.

[0031] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0032] Embodiments of the invention may be implemented upon various types of liquid reservoirs from which there is a risk of the release of an undesirable substance, such as dams, ponds, lagoons, landfdl leachate lakes, large open-top storage tanks, etc. Some embodiments are particularly advantageous for use with bodies of liquid undergoing aeration and / or agitation that creates bubbly-liquid, frothing, foaming, and aerosol / vapour emissions. This is because aeration / agitation may cause concentration and deposition of the undesirable substances upon the surface of the reservoir, which may ultimately lead to the undesirable substances being released into the surrounding environment and in particular the atmosphere. For the sake of providing a detailed example, the illustrated embodiment is depicted as being implemented within a sewerage treatment plant 1. Embodiments of the invention may be retrofitted onto pre-existing facilities or may be incorporated into the design of new facilities. Embodiments of the invention may be engineered to capture a wide range of substances. For example, the substance may be: an organic substance; a surfactant; an amphiphilic substance; floating matter such as microplastics; materials deposited at the upper layer of the water body via an air lift mechanism; a perfluoroalkyl or a poly-fluoroalkyl substance (PFAS); a bubbly-liquid; a froth; a foam; an aerosol; and / or a vapour. The illustrated embodiment is mainly focussed on the capture of per and polyfluoroalkyl substance (PFAS), which may include one or more of the groups comprising: perfluoro-octane sulfonate (PFOS); perfluoro-octanoic acid (PFOA); perfluoro-n-hexane sulfonic acid (PFHxS); perfluorononanoic acid (PFNA); perfluoro-decanoic acid (PFDA / Ndfda); 6:2-fluorotelomer sulphonate compounds (6:2 FTS); 8:2-fluorotelomer sulphonate compounds (8:2 FTS); perfluoro-octanoic acid (PFHpA); poly fluorinated carboxylic acids, alkyl sulfonates and alkyl sulfonamide compounds; fluorotelemeric compounds, each having differing carbon chain lengths; and including precursors of these.

[0033] The substance capture apparatus includes at least one sheet material 2 sized to substantially cover the surface 3 of the liquid reservoir 4. The goal is to prevent / minimise the amount of untreated substance that escapes into the atmosphere and also remove the substance from the wastewater so it does not flow to the final treated water effluent discharge point, thus allowing the wastewater treatment facility to then further concentrate the removed contaminate (eg. PFAS) using the SAFF® process or alternative concentration technology to process along with optional pairing to PFAS destruction cell technology, which requires concentrated waste volumes to become economically viable. Consistent with this goal, it is preferable for the sheet material 2 to cover as much as practicable of the surface 3. The drawings show the surface being partially covered by the sheet material 2. However, this is only for illustrative purposes. Once the embodiment is fully implemented, substantially the entire surface 3 of the liquid reservoir 4 would be covered.

[0034] If available, a large single piece of sheet material 2 may be used to cover substantially the entirety of the surface 3. This forms a gas-tight seal, or a substantially gastight seal, to seal gasses emerging from the surface of the liquid reservoir 4 from the ambient atmosphere. However, more commonly, a number of separate pieces of sheet material 2 are joined together using one or more joining techniques. In one such joining technique, the sheet material 2 is a type of fabric and the edges of adjacent sheet material pieces 2 are sealed to each other in-situ to form a gas-tight seal, or a substantially gas-tight seal, with the use of fabric welding techniques. Another example of such a joining technique is to provide interleavable pockets along the edges of the pieces of sheet material 2 and to run an elongate member, such as a piece of rope or a rod, through the interleaved pockets.

[0035] In other embodiments, the liquid reservoir 4 may already be covered, for example by a metal or hard plastics sheet material. If such pre-existing covering is sufficiently gas-tight, there may be no requirement to retrofit any additional sheet material to cover the surface 3.

[0036] In one embodiment the at least one sheet material 2 is gas impermeable, or substantially gas impermeable, for example a largely impermeable fabric or PVC alloy. Other desirable properties for the sheet material 2 include being PFAS-free, UV and puncture resistant, and having a relatively high tensile strength. The sheet material 2 may be, or include, a high-density polyethylene (HDPE) plastics material, a linear low density polyethylene (LLDPE) plastics material, a PVC alloy; and / or a woven synthetic polyester fabric. In one embodiment the sheet material 2 is formed from tightly woven fibres fixed with resin, tempered and sealed with a coating. Some implementations, particularly in cold climates, may benefit from the use of a thermally insulative material.

[0037] In some embodiments the sheet material 2 is forms a gas-tight seal, or a substantially gas-tight seal, with the periphery of the surface 3 of the liquid reservoir 4. In other embodiments, it forms the seal at a position that is close to the periphery. The peripheral sealing may be achieved in various ways. One embodiment makes use of a hard seal, such as a c-channel rail that extends around the reservoir periphery. A rope encapsulated edge on the sheet material 2 allows the sheet material to be mechanically sealed to the periphery. Another embodiment makes use of tensioning straps or an attachment option such as hook and loop fasteners to retain the sheet material 2 against the periphery. Yet another embodiment makes use of a floating peripheral seal that is shaped to fit within and generally correspond to the shape of the periphery. The floating peripheral seal may be formed from a solid material (e.g. polystyrene) or it may be inflatable. The lower side of the floating peripheral seal floats on surface and inhibits gasses passing underneath or through the floating peripheral seal. The sheet material 2 is attached to the upper side of the floating peripheral seal.

[0038] There is a potential risk associated with the use of a floating peripheral seal because it is only the weight of the arrangement that keeps it down on the surface 3. Hence, wind gusts could potentially get under the floating peripheral seal and lift it off the surface 3. For this reason, some embodiments make use of one or more tethers to tether the floating peripheral seal to the periphery. Indeed, some embodiments making use of the floating peripheral seal include some latitude for the system to accommodate exceptionally high wind conditions. Such embodiments are configured to allow a limited portion of the floating peripheral seal to be lifted by high winds and for excessive wind pressure underneath the sheet material 2 to be relieved at predefined points along the floating peripheral seal.

[0039] A spacer arrangement is disposed at or above the surface 3 of the liquid reservoir 4 so as, in use, to retain the sheet material 2 above the surface and thereby maintain an interstitial space intermediate the surface 3 and the at least one sheet material 2.

[0040] In one embodiment the spacer arrangement is configured to support the sheet material 2 at a minimum vertical distance of about 25 cm above the surface 3 of the liquid reservoir 4. This minimum is aimed at minimising the risk of the sheet material 2 being allowed to drape down into the liquid. In an embodiment, the spacer arrangement supports the sheet material 2 at a maximum vertical distance above the surface 3 of the liquid reservoir 4 of about 100 cm. This maximum is aimed at minimising the risk of the sheet material 2 being caught by a wind gust and lifted upwards or inflated like a balloon. The risk of being lifted upwards is applicable to some embodiments in which it is merely the weight of the arrangement that keeps it on the surface 3 of the liquid 4, such as embodiments that make use of a floating peripheral seal, as described above. This may be contrasted with embodiments that mechanically seal the sheet material 2 at the periphery, for which there is typically substantially less risk of lifting.

[0041] It is within the interstitial space that the undesirable substance is captured by the sheet material 2 until it is subsequently evacuated. The evacuation is done through at least one length of conduit 7 having a plurality of inlets 8 disposed thereupon. The inlets 8 are in fluid communication with the interstitial space. More particularly, as best shown in figures 3 and 4, the lengths of conduit 7 are generally circular in cross section (although it will be appreciated that other cross sectional shapes may be utilised in other embodiments) and the inlets 8 are disposed on the lower halves of the conduits 7. This provides the inlets 8 with clearance from the sheet material 2 that is draped across the upper halves of the conduits 7. A lower line of inlets 8 is maintained at a height that is slightly above the level of the surface 3 of the liquid reservoir 4. As best shown in figure 18, at least some of the lower inlets 8a are preferably disposed upon the conduit 7 such that, in use, they are positioned at or just above the surface 3 of the liquid reservoir 4. This allows those inlets 8a to be positioned to draw in substance in the form of froth, foam and / or bubbly liquid (illustrated as the larger dots in figure 18) that is floating on the surface 3, whilst avoiding bulk in-take of liquid. An upper line of inlets 8b is disposed just below the centre lines of the conduits 7. The inlets 8b can draw in the undesirable substance in the form of foam, froth, bubbly liquid, aerosols and / or vapour (illustrated as the smaller dots in figure 18). Ideally, this is performed with a minimum of liquid from the liquid reservoir 4 being drawn into the inlets 8. Many water treatment plants conduct de-nitrification processes that are adversely effected by the accumulation of froth and foam at the water’s surface. Hence, in such implementations, the removal of froth and foam from the water’s surface by suction through at least some of the lower inlets 8a offers the dual benefits of removing the problematic contaminants entrained within the froth and foam, along with improving the effectiveness of the de-nitrification processes.

[0042] In many implementations the sheet material 2 must be supported above the surface 3 of the liquid reservoir 4 across a fairly expansive area. For such embodiments it is advantageous for the spacer arrangement to be in the form of an array that provides adequate support across the surface 3. The array itself must be supported above the surface of the liquid reservoir and this may be achieved in various ways. In one embodiment the array is formed of a plurality of rigid elongate members, such as metal bars that are anchored at, or adjacent to, a periphery of the liquid reservoir 4. These metal bars extend upward from the periphery to reach a desired height above the surface. They then bend and extend horizontally across the surface 3, before bending downwards for anchorage at the far end of the periphery. In this embodiment, the sheet material 2 is draped over the metal bars. In another embodiment, the array is formed of a plurality of elongate flexible elements, for example metal cables, which are anchored at the desired height at positions around the periphery of the surface 3. The metal cables are held under tension, which allows them to extend across the surface at the desired height until they reach an anchorage point at the opposite end of the periphery. In this embodiment, the sheet material 2 is draped over the metal cables.

[0043] In the illustrated embodiment, as best shown in figures 2, 3 and 4, the spacer arrangement 5 includes a plurality of solid or inflatable floatation elements 9. Each of the floatation elements 9 has a generally triangular base shape defining a lower side configured for immersion within the liquid reservoir 4. The upper half of each of the floatation elements 9 defines an opposite side having semi-circular cut-out that is shaped to abuttingly receive and support the array of conduits 7. In this illustrated embodiment, the conduits 7 perform a dual role. The external surface of the conduits 7 function (together with the floatation elements 9) as the array of the spacer arrangement 5. The internal surface of the conduits 7 function to evacuate the undesirable substance.

[0044] As shown for example in figure 2, the array of conduits 7 includes a plurality of lengths of conduit 7 that extend across the surface 3 from a proximal end of the periphery of the surface 3 to a distal end of the periphery. Each of these lengths of conduit 7 manifold into a collector line of conduit 7 that extends along the proximal edge of the periphery. The downstream end of this collector line of conduit 7 feeds to the condenser tank 16 that is a part of the on-shore holding and processing system 15.

[0045] A formation is provided immediately downstream of each of the inlets 8 of the conduits 7. The formation is shaped so as to capture condensate formed as fluid enters the inlet 8. This stops, or at least inhibits, condensate from leaking out of the inlet 8 and falling back into the liquid reservoir 4. In some embodiments, the formation is in the form of an elbow.

[0046] For some embodiments in which a substantial amount of the undesirable substance is likely to accumulate on the surface 3 in the form of foam, froth and / or bubbly liquid, it is beneficial to deploy at least one free floating fluid recovery system 11 as illustrated in figure 5 into the liquid reservoir 4. In some markets these systems 11 are known as ‘delta skimmers’ and they are marketed by Vikoma International Ltd. These systems 11 may be considered as a type of floating weir. The free floating fluid recovery system 11 has a head 12 at a distal end of a pipe 13. The head 12 is configured to float at the surface 3 of the liquid reservoir 4. This positions at least one inlet 14 on the head 12 at or just above the surface 3. This positioning is suitable for drawing the foam, froth and / or bubbly liquid into the free floating fluid recovery system 11. The pipe 13 manifolds into the conduits 7 and hence the substance as collected by the system 11 is evacuated to the on-shore holding and processing system 15 in a similar manner to the way in which the substance drawn in through the inlets 8 of the conduits 7 is evacuated. The downstream end of the collector line of conduit 7 is connected to vacuum suction equipment 17, in the form of a vacuum blower. In some implementations, the vacuum suction equipment 17 is installed along with the other components of the preferred embodiment and is therefore unrelated to any existing on-site infrastructure. However, in other embodiments the vacuum suction equipment 17 utilises the air intake point of on-site aeration equipment that may have been preexisting within the water treatment plant. This utilisation of existing infrastructure may improve efficiencies and reduce the costs associated with retrofitting the preferred embodiment into an existing water treatment plant.

[0047] A vacuum generated by the vacuum suction equipment 17 is communicated along the conduits 7 to the plurality of inlets 8 so as to draw the substance into inlets 8 and displace the substance along the conduits 7 for depositing into the on-shore holding and processing system 15 disposed at a downstream end of the conduits 7.

[0048] In some embodiments the discharge air of the vacuum suction equipment 17 is released into the atmosphere. However, there is a possibility that the discharge air may include some of the undesirable substance, particularly in vapour or aerosol form. Hence, the discharge air is preferably filtered through a granular activated carbon filter condensate trap or similar air filtration canister to remove any of the undesirable substance before it is released into the atmosphere. In other embodiments making use of a closed loop air supply system in which the air intake for the aeration equipment is used to generate the vacuum required to recover the foam / aerosols, the discharge air from the vacuum suction equipment 17 is recirculated into the aeration system that aerates the liquid reservoir 4. For this embodiment, it is not necessary to filter the discharge air because the undesirable substance will simply be returned into the liquid reservoir 4 and therefore be subject to another round of capture and processing.

[0049] As best shown in figure 9, the condenser tank 16 has two or more upwardly extending baffles that are interleaved with two or more downwardly extending baffles. This is configured to intercept passage of the substance as it is displaced between the condenser tank inlet and the condenser tank outlet. A liquid, for example water, is housed within the condenser tank 16. The height of the liquid, combined with the heights of the baffles, are configured to ensure that the substance must pass through the liquid as it is displaced between the condenser tank inlet and the condenser tank outlet. A controller is used to maintain the water level at the desired level.

[0050] After passing through the condenser tank 16, the substance is displaced to temporary holding tanks 18 to accumulate to a volume suitable for further processing. Once this has accumulated, the substance is displaced from the temporary holding tanks 18 to an apparatus for separation of the substance from water 19. This apparatus 19 is as disclosed in PCT / IB2018 / 059830 (published as WO2019 / 111238), the full contents of which are hereby incorporated by way of reference. This apparatus is referred to commercially by the applicant as Surface Active Foam Fractionation, or SAFF®. This further concentrates the substance.

[0051] After being concentrated by the SAFF® process, the substance is displaced from the apparatus 19 to a substance destruction apparatus 23. This destroys the concentrated waste by use of a containerized third-party PFAS destruction cell technology. It will be appreciated by those skilled in the art that the processing provided by the preferred embodiment, when combined with the further processing that occurs in the clarifier ponds 20 and in the fractionation pits 22, is an example of general approach commonly referred to as a treatment train approach.

[0052] For those embodiments in which the liquid reservoir 4 is being aerated, the aeration process results in the passage of air up through the liquid reservoir 4 to emerge into the interstitial space. For embodiments in which the sheet material 2 forms a gas-tight seal with the periphery of the surface 3 of the liquid reservoir 4, this can potentially result in a build up of gas pressure within the interstitial space. This build up of gas pressure must be balanced against the reduction of gas pressure caused by the evacuation of gasses from the interstitial space resulting from operation of the vacuum suction equipment 17. One option to control this balance is to dispose a gas pressure sensor within the interstitial space. The gas pressure sensor is configured to provide a digital output that is indicative of a measured gas pressure value within the interstitial space. This output is provided to a controller unit that is configured to process the gas pressure value and, responsive thereto, to output a control signal to control the operative level of the vacuum suction equipment 17. If the pressure value is above an upper threshold, there may be a risk of over inflation, which could rupture the sheet material 2. Hence, the controller issues a control signal requesting the vacuum suction equipment 17 to operate at a higher level. This causes a stronger vacuum to be applied to the foam / aerosol extraction system, resulting in more rapid evacuation of material from the interstitial space, which lowers the pressure within the interstitial space. If the pressure value is below a lower threshold, there may be a risk of the sheet material 2 making contact with the water surface. Hence, the controller issues a control signal requesting the vacuum suction equipment 17 to operate at a lower level, which results in material being evacuated from the interstitial space at a slower rate, to thereby raise the pressure within the interstitial space. In a typical embodiment, the controller unit is configured to maintain the gas pressure within the interstitial space at slightly higher than ambient air pressure. This may be done by setting the value of the lower threshold to be slightly higher than ambient air pressure and the value of the upper threshold to be slightly higher than the lower threshold.

[0053] Another embodiment makes use of a pressure relief valve configured to vent gasses from the interstitial space to the ambient atmosphere if pressure within the interstitial space exceeds a threshold. This can be used in addition, or as an alternative, to the arrangement discussed in the preceding paragraph. If used in addition, it provides a failsafe option that may be beneficial if the arrangement discussed in the preceding paragraph fails, for example due to a failure of the vacuum suction equipment 17, the controller or the gas pressure sensor. If such a failure causes the pressure within the interstitial space to increase substantially above the upper threshold enforced by the control system, the pressure relief valve provides a safety back-up.

[0054] It will be appreciated that the above-described apparatus and process results in capture of at least a proportion of the undesirable substance from the liquid reservoir 4 and its evacuation to the on-shore holding and processing system 15. Once aerated, the water in the liquid reservoir 4, which is likely to still contain some of the undesirable substance, moves through to the clarifier ponds 20, which typically removes more of the undesirable substance in the form of sludge. The water then proceeds onto multiple in-situ flow-through fractionation columns 21 submerged in dedicated pits / ponds 22 that are designed to remove additional amounts of the undesirable substance. The illustrated embodiment depicts a sewerage treatment plant 1 having two fractionation pits 22, however other embodiments may have less or more, with some particularly advantageous embodiments featuring three fractionation pits. The combination of the benefits provided by the covered surface 3 of the preferred embodiment, along with the other various treatments in the clarifier ponds 20 and the fractionation pits 22, allows for a very high-volume flow-through treatment. It also allows for a more efficient utilisation of the SAFF® apparatus.

[0055] In addition to the environmental and process benefits of the preferred embodiment, the coverage of the surface 3 by the sheet material 2 provides other benefits. This includes improved safety for the facility workers by limiting or eradicating their exposure to the undesirable substance, especially when in the aerosol & vapour form. This limits or eradicates the potential for pathogen inhalation. An additional safety measure is minimising or eradicating the risk of drowning in the aerated waters of the reservoir 4.

[0056] While a number of preferred embodiments have been described, it will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the invention without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A substance capture apparatus for use with a liquid reservoir defining a surface, the apparatus including: at least one sheet material sized to substantially cover the surface of the liquid reservoir; a spacer arrangement configured for disposition at or above the surface so as, in use, to retain the sheet material above the surface and thereby maintain an interstitial space intermediate the surface and the at least one sheet material; and a conduit having a plurality of inlets disposed thereupon such that, in use, the plurality of inlets are in fluid communication with the interstitial space.

2. A substance capture apparatus according to claim 1 wherein the at least one sheet material is sized to cover a substantial entirety of the surface of the liquid reservoir so as, in use to form a gas-tight seal, or a substantially gas-tight seal, to seal gasses within the interstitial space from the ambient atmosphere.

3. A substance capture apparatus according to claim 1 or 2 wherein the at least one sheet material is formed from, or includes, at least one of: a high-density polyethylene (HDPE) plastics material; a linear low density polyethylene (LLDPE) plastics material; a PVC alloy; or a woven synthetic polyester fabric.

4. A substance capture apparatus according to any one of claims 1 to 3 wherein the spacer arrangement includes an array configured to be supported above the surface of the liquid reservoir.

5. A substance capture apparatus according to claim 4 wherein the array is formed of a plurality of rigid elongate members, the array being configured for anchorage at, or adjacent to, a periphery of the liquid reservoir or wherein the array is formed of a plurality of elongate flexible elements held under tension, the array being configured for anchorage at, or adjacent to, the periphery.

6. A substance capture apparatus according to claim 4 wherein the spacer arrangement includes a plurality of solid or inflatable floatation elements, each of the floatation elements defining a lower side configured for immersion within the liquid reservoir and an opposite side configured to abut and support the array.

7. A substance capture apparatus according to claim 4 or 6 wherein the array of the spacer arrangement is formed by the conduit.

8. A substance capture apparatus according to any one of the preceding claims wherein a formation is provided immediately downstream of each of the inlets of the conduit, the formation being shaped so as to capture condensate formed as fluid enters the inlet and thereby stop or inhibit condensate from leaking back into the liquid reservoir.

9. A substance capture apparatus according to any one of the preceding claims wherein the liquid reservoir is at least one of: a dam; a landfill leachate lake; a sewerage treatment pond; or a body of liquid undergoing aeration.

10. A substance capture apparatus according to any one of the preceding claims wherein the spacer arrangement is configured to support the sheet material at a minimum vertical distance above the surface of the liquid reservoir of about 25 cm and at a maximum vertical distance above the surface of the liquid reservoir of about 100 cm.

11. A substance capture apparatus according to any one of the preceding claims including at least one free floating fluid recovery system configured to float at the surface of the liquid reservoir so as to position at least one inlet at or just above the surface for drawing of the substance into the free floating fluid recovery system.

12. A substance capture apparatus according to claim 2 including a gas-tight seal, or a substantially gas-tight seal disposed around a periphery of the surface of the liquid reservoir so as to seal the at least one sheet material to the periphery.

13. A substance capture apparatus according to claim 2 or 12 wherein the sheet material is formed from a plurality of sheet material pieces, with edges of adjacent sheet material piecesbeing sealed to each other to form a gas-tight seal, or a substantially gas-tight seal, with the use of a joining process.

14. A substance capture apparatus according to any one of the preceding claims, wherein the substance is at least one of: an organic substance; a surfactant; an amphiphilic substance; floating matter; material deposited at an upper layer of the water body; a perfluoroalkyl or a polyfluoroalkyl substance (PFAS); a bubbly-liquid; a froth; a foam; an aerosol; and / or a vapour.

15. A substance capture apparatus according to claim 14 wherein the perfluoroalkyl or polyfluoroalkyl substance (PFAS) includes one or more of the groups comprising: perfluorooctane sulfonate (PFOS); perfluoro-octanoic acid (PFOA); perfluoro-n-hexane sulfonic acid (PFHxS); perfluorononanoic acid (PFNA); perfluoro-decanoic acid (PFDA / Ndfda); 6:2- fluorotelomer sulphonate compounds (6:2 FTS); 8:2-fluorotelomer sulphonate compounds (8:2 FTS); perfluoro-octanoic acid (PFHpA); poly fluorinated carboxylic acids, alkyl sulfonates and alkyl sulfonamide compounds; fluorotelemeric compounds, each having differing carbon chain lengths; and including precursors of these.

16. A substance capture apparatus according to any one of the preceding claims wherein a downstream end of the conduit is connectable to vacuum suction equipment, whereby, in use, a vacuum generated by the vacuum suction equipment is communicated along the conduit to the plurality of inlets so as to draw the substance into an upstream end of the conduit and displace the substance along the conduit for depositing into an on-shore holding and processing system disposed at a downstream end of the conduit.

17. A substance capture apparatus according to claim 16 wherein the on-shore holding and processing system includes a condenser tank having at least one baffle configured to intercept passage of the substance as it is displaced between a condenser tank inlet and a condenser tank outlet.

18. A substance capture apparatus according to claim 17 wherein a liquid is housed within the condenser tank and wherein the at least one baffle is configured to ensure that thesubstance passes through the liquid as it is displaced between the condenser tank inlet and the condenser tank outlet.

19. A substance capture apparatus according to claim 17 or 18 wherein the substance is displacable from the condenser tank to a temporary holding tank to accumulate to a volume suitable for further processing.

20. A substance capture apparatus according to claim 19 wherein the substance is displacable from the temporary holding tank to an apparatus for separation of the substance from water.

21. A substance capture apparatus according to claim 20 wherein the substance is displaced from the apparatus for separation of the substance from water to a substance destruction apparatus.

22. A substance capture apparatus according to any one of claims 16 to 21 including a gas pressure sensor disposed within the interstitial space, the pressure sensor being configured to provide a gas pressure value to a controller unit, the controller unit being configured to process the gas pressure value and, responsive thereto, to output a control signal to the vacuum suction equipment, the control signal being indicative of a desired operative level of the vacuum suction equipment.

23. A substance capture apparatus according to claim 22 wherein the controller unit is configured to maintain gas pressure within the interstitial space at slightly higher than an ambient air pressure.

24. A substance capture apparatus according to any one of claims 16 to 23 wherein the vacuum suction equipment is provided at least in part by preexisting on-site aeration equipment.

25. A substance capture apparatus according to any one of the preceding claims including a pressure relief valve configured to vent gasses from the interstitial space to the ambient atmosphere if pressure within the interstitial space exceeds a threshold.

26. A substance capture apparatus according to any one of the preceding claims wherein at least some of the inlets disposed upon the conduit are, in use, positioned at or just above the surface of the liquid reservoir such that said at least some of the inlets are positioned to draw in substance in the form of froth, foam and / or bubbly liquid that is floating on the surface whilst avoiding bulk in-take of liquid.

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