AU2009295248A2

AU2009295248A2 - Buoyant panel

Info

Publication number: AU2009295248A2
Application number: AU2009295248A
Authority: AU
Inventors: Alfred Johannes Biden; Bernard Kent Masters; Kevin Michael O'Donnell
Original assignee: Floating Islands Australasia Pty Ltd
Current assignee: Floating Islands Australasia Pty Ltd
Priority date: 2008-09-19
Filing date: 2009-09-01
Publication date: 2011-04-14
Also published as: WO2010031106A1; AU2009295248A1

Description

WO 2010/031106 PCT/AU2009/001131 BUOYANT PANEL Field of the Invention The present invention relates to a buoyant panel for use on bodies of water. In particular, 5 the panel of the present invention finds application in a number of areas including: (i) as an artificial island hosting plants, wherein the plants are useful in water treatment; (ii) as an artificial island hosting plants, wherein the plants are useful in providing bird nesting habitats and/or protective shelter for fish and crustaceans; (iii) as an artificial island hosting plants, wherein the plants are used for beautification of the environment; (iv) for 10 evaporation control; and (v) for wave damage control. Background of the Invention Floating platforms are known to exist in a number of forms and for a number of purposes. Typically, each of these platforms is intended to be used for a specific purpose. 15 Floating platforms have previously been used as planters or as artificial islands. A number of known floating planters are covered by materials that prevent or restrict plant growth. For example, some include a floatation layer that is manufactured from conventional buoyant foam, such as a foamed plastic. However, this material is not 20 suitable for plant growth and regions of the foam layer must be cut out so that plants roots can grow through the planter and spread. into the water therebeneath. Other background art planters use hollow buoyant pipes as a frame formed around the perimeter of the structure to provide buoyancy. For example, scaled PVC or polyethylene tubes placed around the perimeter of a floating planter are sometimes used to provide 25 buoyancy thereto. This method of providing buoyancy tends to be fragile, in that it is subject to failure by impact from boats and pressure from environmental conditions and furthermore, has limited manufacturing capability. Planters can also be constructed from interwoven or spun-bonded structures that contain buoyant components in appropriate positions to provide a degree of stability. 30 WO 2010/031106 PCT/AU2009/001131 2 Various man-made floating structures are known that do support flora. These structures generally have scaled hollow pipe-framed perimeters and an internal membrane constructed from synthetic or naturally occurring materials stretched therebetween, which support water-tolerant plants or plant containers placed therein or thcreon. However, the 5 buoyancy of such a structure is vulnerable in that simple rupturing of the plastic pipe can allow ingress of fluid resulting in the entire structure sinking. Research has shown that particular water-plants and land-plants can be effective in the purification of contaminated waters. The high surface area of the root system of such 10 plants facilitates the formation of a 'biofilm' at an appropriate position with respect to the waterline, which can dramatically improve the aquatic environment in which the biosphere is situated. This research has also shown that the efficiency of such plants is reliant on a series of factors, including the provision of a cost-effective and stable buoyant structure; an appropriate root support medium; and a containment system. By 15 their form and design, such planted floating planters provide benefits such as water purification, visual beautification and the provision of habitats for birds and protection to fish life. Some floating platforms have also been used to cover bodies of water in order to prevent 20 excessive water evaporation. When water evaporation occurs, this affects not only the loss of a valuable resource, but also provides a method by which water impurities and water-soluble agents become concentrated in that body of water. Water bodies in warmer climates are subject to heating up under direct exposure to sunlight, thereby promoting the growth of blue-green algae in nutrient rich waters and prohibiting the development of 25 a natural biosphere, where this might otherwise be desirable. In many instances, it is most desirable to achieve both the suppression of water evaporation in combination with the purification of contaminated water. Water evaporation suppression systems are commercially available. The technology of 30 these systems ranges from the provision of a surface layer of surfactant with and without repelling powders and foamed pellets, through to foils and discs of self-supporting WO 2010/031106 PCT/AU2009/001131 designs being laid onto the water bodies; and shade cloths stretched by elaborate frameworks over the water surface. However, some surface films/powders/pellets and surface foil applications suffer from instability. This feature contributes to safety issues of such covering systems, particularly the foil cover, when applied directly onto the water 5 surface. Most systems incur high costs and present difficulties with respect to installation and maintenance. Fully impermeable foil systems are also susceptible to wind lift and sinking under heavy rainfall and/or deposition of sand/dust from dust storms. Wave action can cause erosion of natural or artificial boundaries of such water bodies. 10 Wave erosion is generally mitigated by the construction on the shore-line of fixed structures, quch as rocky batters/slopes or liners. However, such structures are expensive to install and maintain, and may be prone to damage. The present invention seeks to provide an improved buoyant panel. More particularly, the 15 present invention provides a buoyant panel, which seeks to minimize or ameliorate the disadvantages of the prior art. Summary of the Invetition According to the present invention, there is provided a buoyant panel for use on a body.

20 of Water, the panel comprising a buoyant perimeter frame and a perforatable membrane substantially located tber6within and substantially supported thereby, the frame being constructed of a close -cell foamed polymeric material having a substantially solid or hollow centre or a combination thereof. 25 The buoyant perimeter frame of the buoyant panel substantially provides structural stability and buoyancy for the buoyant panel, as well as support for the perforatable membrane. The major advantage provided by the present invention is that the buoyant perimeter frame- is made to be inherently buoyant through use of the closed-cell foamed polymeric material frorn vhich the frame is constructed due to the air trapped within the 30 material during the manufacturing process. While fluid could still enter the material, the material will remain substantially afloat and the perimeter frame is still able to WO 2010/031106 PCT/AU2009/001131 4 substantially support additional weight, such as the perforatable membrane and any load applied thereto. The buoyaut perimeter frame is preferably composed of one or more frame members, 5 used in combination, wherein the frame member comprises a continuously extruded polymer of closed-cell or closed-cell walled hollow tube or a combination thereof. Joining together of the frame members to make the buoyant perimeter frame of the buoyant panel may be achieved by any method known in the art, for example, but not limited to, heat-welding, screwing, riveting and/or stapling together. 10 One preferred embodiment of the frame member is a rod formed from foamed polyethylene, having a density of from approximately 0.45 g/cm 3 to approximately 0.75 g/cm3. More preferably, the density of the rod is from approximately. 0.5 g/cm 3 to approximately 0.6 g/cm 3 . The source of polyethylene is most preferably impure recycled 15 plastic, such that it includes other scrap plastics. During manufacture, this material is preferably mixed with a blowing agent, for example, azodicarbonamide, and the closed cell foan rod is produced therefrom Using standard extrusion techniques. The effective diameter of the frame member is preferably determined by the amount of 20 buoyancy required for a particular application. A preferred frame member diameter is in the order of between about 30 mm to about 100 mm, while a most preferred diameter is about 50mm. The buoyant panel may be of any shape, including but not limited to triangular, 25 quadrilateral, pentagonal, hexagonal and octagonal. Generally, the shape of the buoyant panel wilt have substantially straight sides, since substantially straight rods of the foamed polymeric profile are more readily prepared than curves, Furthermore, straight edged shapes are more readily assembled and used as modular components for being tethered together as described above to form a buoyant structure. 30 WO 2010/031106 PCT/AU2009/001131 5 In order to provide additional structural stability to the buoyant panel or structure, some embodiments of the present invention further comprise opposite sides of the buoyant perimeter frame being spaced apart by one or more cross-members placed therebetween. These cross-members are typically constructed from the same material as the buoyant 5 frame members. As discussed in detail below, the perforatable membrane may include additional sleeves or pockets to accommodate the one or more cross-member/s. Artificial islands or, as also referred to herein, Floating Biospheres, can preferably be used for groWing vegetation to assist in bioremediation of waterways; to provide habitats 10 for various organisms, including birds; or for beautifying waterways. When used for the bioremediation of waterways, careful selection of plants can result in the formation of bio-films on the roots of such plants, which can dramatically improve the aquatic environment in which the artificial island is situated. The filler medium combinations of the buoyant panel also contribute, due to their large surface area, to the rapid growth of 15 the root system of the plants and also, at the submersed portion, to the formation of bio film and at the non-submersed portion, to aeration of water from natural circulation. The. modular construction of such a buoyant structure allows a large area of-the body of water to be covered. 20 The present invention also preferably provides at least one buoyant panel, whose buoyancy is variable depending on the composition of the frame and the filler medium in combination with the perforatable membrane used therein. Preferably, a number of buoyant panels may be used in combination as modular units. There are two main types of buoyant panels according to the present invention, namely, Floating Biospheres that 25 are used for growing plants and Floating Covers that are used in evaporation and wave suppression applications. The modular nature of the buoyant panels allows for easy construction of a variety of sizes of Floating Biospheres or Floating Covers, depending on the requirements of the body of water. 30 In a first preferred aspect, the buoyant panel of the present invention functions as a Floating Biosphere and in particular, provides an artificial island which supports water WO 2010/031106 PCT/AU2009/001131 6 tolerant plants. In this aspect of the invention, the perforatable membrane is preferably one which is able to be permanently immersed in water without long-term deterioration. The nature and construction of the perforatable membrane may vary depending on the intended use of the buoyant panel- of the present invention. Typically, the membrane is 5 preferably constructed from a fabric having an open weave to permit plant root penetration. Furthermore, the fabric selected most preferably has the capability of being sewn or welded together by appropriate joining techniques. In this first aspect, the perforatable membrane is substantially fillable with a filler 10 medium. The filler medium consists substantially of water-resistant materials composed of natural and/or synthetic open cell foam, short fibres or shredded fabrics, plastics pellets/granules or purpose specific polymeric or inorganic particulates and closed cell plastics particulates. The tiller medium composed of the different composition materials is selected from being uncoated or coated or a combination thereof. Where the filler 15 medium is coated, polymeric adhesives randomly mixed into -a fluffy, pervious but coherent consistency arc preferably used. The filler medium of the present invention is more preferably provided by one or by a. combination of more than one of three types of material, each of which serves a specific 20 function. The three types of material are: a) chips of closed cell foam of polymeric nature of rigid or flexible foam origin; b) chips of open cell foam of polymeric nature of rigid or flexible foam origin; and c) short fibres or shredded fabric of natural fibre or synthetic fibre origin or combination thereof, 25 Where the filler medium includes chips of closed cell foam of polymeric nature of rigid or flexible foam origin, the material can contain water-insoluble impurities. The closed cell foam provides additional buoyancy to the buoyancy provided by the- buoyant perimeter frame member, by water displacement at the immersed filler medium portion of the buoyant panel. This material is most preferably, but not limited, to expanded 30 polystyrene.

WO 2010/031106 PCT/AU2009/001131 7 Where the filler medium material includes chips of open cell foam of polymeric nature of rigid or flexible foam origin, the material can further contain water-insoluble impurities. This material predominantly provides structural stability to the filler medium, but also allows for water penetration for the formation of a biofilm on the roots of flora planted on 5 the panel, which as described above, can dramatically improve the aquatic environment in which the biosphere is situated. Where the filler medium material includes shredded materials consisting predominantly of short fibres or shredded fabrics of spun-, woven- or pressed fibres of polymeric nature, 10 the material can also contain water-insoluble impurities, solid plastics granules, particulates or flakes of plastics originating from film, foil or felt. This material allows for water migration and formation of bio-film due to its high aspect ratio of surface area to material volume. A non-limiting example of this material is shredded carpet. Such a filler medium material also preferably provides additional buoyancy to the buoyant panel. 15 The three types of materials described above can be varied in composition ratio in accordance with design functions and requirements of the buoyant panel, whereby each material provides a specific function within the filler medium. The combination preferably enables regulation of the buoyancy, the overall carrying capacity and stability 20 of the buoyant panel, as well as the position of the waterline within the panel with respect to the planted flora. The filler medium of the above composition enables the possibility for it to be mixed with plant seeds and/or plant cuttings. The filler medium material most preferably consists of a mixture of the three types of 25 material as described above, in a ratio of approximately 1:1:1. In this case, the filler medium has a material density of approximately 0.04 kg/l to approximately 0.07 kg/I, preferably approximately 0.045kg/, and an open cell void factor (solid volume/void volume) of approximately 0.10 to approximately 0.25, preferably approximately 0.135. 30 The separation of the individual functions of components of the filler medium allows great flexibility with respect to adapting :various embodiments for particular functions.

WO 2010/031106 PCT/AU2009/001131 8 Further, buoyancy of the panel is provided by air trapped throughout the frame and the perforatable membrane; by the density of the material from which the perimeter frame is constructed; and by the closed cell foam component of the filler medium; and from material used for membrane and membrane filler medium with a density below 1.0 5 g/cm3. The filler medium is further preferably predetermined to a volume of twice the frame cavity volume in this embodiment of the invention. When the filler medium is inserted into the perforatablc membrane, the membrane forms a substantially flat configuration 10 being, on average, approximately twice the thickness of the diameter of the buoyant frame profile, i.e. 100 mm when the buoyant frame profile has a diameter of 50 mm. In this preferred embodiment, the perforatable membrane which substantially ensures the containment of the filler medium is perforated, whereby dust, water or rain can pass 15 therethrough to prevent the pooling thereof on the surface of the buoyant panel. More - preferably, when the membrane is constructed of a perforated mesh, the pores thereof being of a sufficiently small pore size to substantially inhibit or prevent the filler medium passing through the membrane. 20 Where the membrane is composed of a polymeric woven fabric, the fabric is preferably selected from open mesh, closed mesh or spun-bonded construction, as appropriate for the particular embodiment. One selected fabric construction may be used for the entire membrane or.alternatively can be used in combination with others, whereby the sun exposed part of the membrane is adequately UV-stabilised and all component parts are 25 suitable for long-term water immersion. A more preferred membrane material is commercially available shadecloth. Shadecloth, having a 50% shading rating, is most preferred, as it is lightweight and consists of a single weave, and provides a suitable level of porosity to allow water and dust to be washed therethrough, while still retaining the filler medium therein. 30 WO 2010/031106 PCT/AU2009/001131 9 Since the membrane is exposed to the environment, it is most preferably robust and resistant to degradation. Accordingly, at least the upper surface of the membrane is substantially resistant to environmental degradation, such as UTV-degradation and preferably includes stabilizers and absorbers such as, but not limited to, hindered amine 5 light stabilizers and UV absorbers. Commonly used products include various compounds sold by Ciba, such as the Chimassorb* and Tinuvin* ranges of compounds. Non-limiting examples of hindered amine light stabilizers include Tinuvin 770 (Bis(2,2, 6

,

6

,

tetramethyl-4-piperidyl) sebacate) and Tinuvin* 783 (Poly{[6-[(1,1,3,3 tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl) 10 imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino] Butanedioic acid, dimethylester, polymer with 4-hydroxy-2,2,6,6-tetramethyl-l-piperidine ethanol). Non-limiting examples of UV absorbers include Tinuvin* 571 (2-(2H-benzotriazol-2-yl) 6-dodecyl-4-mcthylphenol) and Tinuvin* 360 (2,2'-methylene-bis[6-(2H-benzotriazol-2 yl)-4-(1,1,3,3-tetramethylbutyl) pbenol]). 15 In a second aspect, the buoyant panel of the present invention functions as a Floating Cover, which can be applied to the water surface for minimising water evaporation or to function as a wave suppressor to reduce wave damage to the land at the edges of a body of water. 20 Preferably, placing Floating Covers of the present invention on a body of water substantially prevents the water from direct sun exposure and thereby reduces both airflow across the water surface and water temperature, resulting in a significant reduction in water evaporation. The modular nature of such buoyant structures allows a 25 large area of the -body of water to be covered. Preferably further, placement. of Floating Covers adjacent to and anchored to, the shore of a clay-lined dam 'or a reservoir substantially reduces wave damage, which would otherwise cause the clay lining thereof to be washed away. Such buoyant structures are 30 able to cascade down the slope of a water dam, reservoir or channel with the change in WO 2010/031106 PCT/AU2009/001131 10 water level, thus further protecting the shore line and prevent the clay-lined dam from cracking. The perforatable membrane used for Floating Covers is typically of a flat-mat 5 construction, which construction is preferably in the form of a laminate. In the laminate embodiment, the membrane is the upper surface layer thereof. To the underside of the laminate, there is preferably provided a lower. surface layer, which layer is adhered or welded to the upper surface layer.. The lower surface layer is more preferably comprised of filler medium, as described above. 10 In certain preferred embodiments, the choice of material from which the membrane is constructed regulates the degree of suppression of water evaporation. The membrane is preferably able to be permanently immersed in water without long-term deterioration. The membrane material used for the evaporation suppression application is preferably a 15 fabric having bonded-fibre configuration, a plastics or aluminium foil having perforations therein on the upper surface of the laminate to control water and dust permeation and a fabric having open-weave or bonded-fibre configuration forming the lowest surface layer. The material chosen most preferably has the capability of being sewn or welded together by appropriate joining techniques. 20 Since the upper surface layer of the laminate is exposed to the environment, it is most preferably robust and resistant to degradation. Accordingly, at least the upper surface layer is substantially resistant to environmental degradation, such as UV-degradation. Accordingly, the laminate may include stabilizers and absorbers such as, but not limited 25 to, hindered amine light stabilizers and UV-absorbers. Commonly used products include various compounds sold by Ciba, such as the Chimassorb@ and Tinuvin@ ranges of compounds. In this embodiment of the present invention, the lower surface layer can be made of a 30 variety of materials, such as chips of open cell foam of polymeric nature of rigid or flexible foam origin, which are randomly bonded by a polymeric bonding compound or WO 2010/031106 PCT/AU2009/001131 composition to retain a coherent water pervious structure. The most preferred material, which acts as a "water weight" for the panel and helps prevent the buoyant panel from being lifted off the water surface by wind movement, is polyurethane flexible foam. 5 The lower surface layer of the laminate of the Floating Cover, which preferably has the same composition ratio and open cell void factor as for the Floating Biosphere, is preferably pre-manufactured as a flat sheet, which can be randomly bonded or welded to the upper surface layer. Suitable adhesives, which ensure the integrity of the laminate, can be those as known in the art of adhesives. The adhesive is preferably an adhesive 10 mastic. In some preferred embodiments of the present invention, the adhesive is an ethylene-vinyl acetate adhesive. The thickness of the laminate is preferably approximately half the thickness of the diameter of the frame profile, Attachment of the perforatable membrane' or in. its laminate form to the buoyant 15 perimeter frame is achieved by any method known to the skilled addressee. In exemplary embodiments of the present invention, attachment is achieved by the use of sleeves or pockets around the periphery of the membrane/laminate resulting in the frame being substantially encased therewithin. In further embodiments, the membrane/laminate is fixed directly to the buoyant perimeter frame. The closed-cell nature of the frame 20 member allows a fastening means to be inserted into the buoyant perimeter frame without compromising or reducing its buoyancy. In some alternative embodiments, the fastening means, for example, a cable tie, may wrap around the outside of the frame. In some particular embodiments of the Floating Cover, the membrane/laminate is 25 prepared with the membrane extending over the top of the perimeter frame. This extended region may be used to link the membrane/laminate to the frame, for example, by fasteners inserted directly into the perimeter frame, by welding, or by usual methods known to those in the art. The flat-mat membrane/laminates can preferably further include an underlayer, wherein the underlayer may also extend beyond the edge of the 30 membrane/laminates and also be used in the attachment of the membrane/laminates to the perimeter frame.

WO 2010/031106 PCT/AU2009/001131 12 The buoyant panel according to the present invention consists of only a limited number of components and. this type of construction permits individual components to be produced separately and then assembled to form a complete panel. This assembly may be 5 performed in a factory or even on site immediately prior to installation on the intended body of water. The profiles of the buoyant perimeter frame members can be manufactured continuously to selected dimensions and cut to size in accordance with the respective design. The 10 buoyant frame structure can be preassenbled or assembled into construction sleeves or pockets within the membrane/laminate. The membrane structure may be pre-prepared according to the respective design and the laminate prepared prior to final assembly as a buoyant panel. Several examples of various possible design options are possible and these will be discussed firther below. The simplicity of the design concept allows for 15 many other geometries should they be required. As discussed above, panels of any shape can be constructed including, but not limited to, triangular, quadrilateral, pentagonal, hexagonal and octagonal. In preferred embodiments of the present invention, a plurality of buoyant perimeter frame 20 members are joined together to form the buoyant perimeter frame which is substantially leak-proof and inherently buoyant. The buoyant perimeter frame members are preferably produced from a virgin polyolefin, polyolefin composites or recycled polyolefin/composite composition. The buoyancy of unfilled polyolefin is more preferably enhanced by the incorporation of a closed-cell processing technique 25 commonly known in the art. As noted above, the density of the frame members is most preferably in the range of 0.45 g/cn 3 to 0.75 g/cm 3 , which density provides the required strength of the frame structure. The buoyant frame perimeter members of the present invention can be joined using any known process, including, but not limited to, heat welding, screwing, riveting or stapling together, without any such process affecting the 30 degree of buoyancy for the construction of a frame structure and any fastening of WO 2010/031106 PCT/AU2009/001131 13 component to the frame for specific applications, e.g. construction of an installation of panels for the creation of an island or attachment of bird-netting fixtures (see below). When interconnected, in a modular manner, the buoyant panels can form large Floating 5 Biospheres or Floating Coyers, wherein the Floating Biospheres are intended to support various flora, and the Floating Covers are intended to act as evaporation or wave suppression covers. The specific buoyancy capacity and panel stability, being varied by the individual panel designs, further enables the design to be varied by the combination of the construction of the membrane/laminate, whereby individual buoyant panels are 10 configured in specific patterns and functions. Accordingly, it is envisaged that combinations of all of the above discussed applications can be constructed depending on the choice of each of the buoyant panels. It is envisaged that different types of panels could be joined together to provide a multifunctional floating cover. 15 It is envisaged that the modular panels may be linked using, for example, 5mm diameter ski-rope passed through a hole drilled in the frame and joined to a loop as practiced in the trade of joining ski-ropes. In yet further embodiments of the present invention, it is desirable to have the buoyant panels fixed in position on the water or to the bank, in the case of a wave suppression application; As noted previously, due to the nature of the 20 buoyant frame members, it is possible to securely attach ropes, chains or the like to the buoyant panels, which chains or ropes etc. may be used to tie the panel to the bank or to an anchor, to position the panel on the water. In certain Floating Biosphere embodiments of the present invention, it is desirable to be 25 able to protect the plants planted thereon from predators, such as birds. To achieve this, the buoyant panel further comprises a support structure formed over the buoyant panel by, for example, placing arches formed of a suitable lightweight material from one side of the buoyant panel to another. The arches are preferably constructed from any suitable lightweight material, for example, plastic piping. One suitable type of plastic piping is 30 garden irrigation pipe, having a diameter of approximately 12mm. Fixing this type of piping to the buoyant frame may be achieved using any suitable means including, but not WO 2010/031106 PCT/AU2009/001131 14 limited to, barbed connectors, such as those typically used in garden irrigation systems, inserted into holes drilled into the buoyant frame. As noted above, it is possible to form holes in the buoyant frame without compromising its buoyancy. Bird netting or the like can then be installed over the support structure to protect the plants during the initial 5 growing phase on the buoyant panel. The bird netting is removed after the plants have established sufficient root mass that is deemed sufficient to prevent the plants from being pulled out or being substantially damaged by grazing bird populations. Preferably, the buoyant structure of the present invention is easy to install, plant with 10 flora and maintain. The materials from which the buoyant structure is made are preferably eco-friendly (i.e. to water, flora and fauna), long-lasting and potentially recoverable, when the structure is no- longer required or when it reaches the end of its useful life. [5 Description of the Drawings. Other features and advantages of one or more preferred embodiments of the present invention will be readily apparent to one of ordinary skill in the art from the following written description with reference to, and used in conjunction with, the accompanying drawings. 20 Figure 1 shows cross-sections of various embodiments of the buoyant perimeter frame member of the present invention. Figure 2 shows a cross-section of a flat-mat membrane/laminate embodiment of the 25 present invention. Figure 3 illustrates exemplary embodiments used as components of the perforatable membrane/laminate of the present invention: A. woven, open mesh fabric; B. spun bonded (fused fibre) short fibre fabric; and C. perforated plastic- or Aluminium (Al)-foil. 30 WO 2010/031106 PCT/AU2009/001131 15 Figure 4 illustrates an exemplary -embodiment of the buoyant panel according to Example 1, end-on view (A) and plan view (B). Figure 5 illustrates exemplary embodiments of the buoyant panel according to Example 5 2-a Floating Biosphere embodiment is shown in end-on view (A) and in plan view (B); and a Floating Cover embodiment is shown in plan view (C) and in cross-section through D-D' (D) as identified in (C). Figure 6 illustrates an exemplary embodiment of the buoyant panel according to 10 Example 3, end-on (A), plan (B) and side-on (C) views. Figure 7 illustrates an. exemplary embodiment of the buoyant panel according to Example 4, end-on (A), plan (B) and side-on (C) views. 15 Figure 8 illustrates an exemplary embodiment of the buoyant panel according to Example 5, end-on (A), plan (B) and side-on (C) views. Figure 9 illustrates an exemplary embodiment of a disassembled buoyant panel according to Example 6, the buoyant frame is shown in plan view (A) and end-on view 20 (B), and the perforatable membrane is shown in plan view (C) and end-on vicw (D) Figure 10 illustrates an exemplary embodiment of an assembled buoyant panel according to Example 6, plan view (A) and end-on view (B). 25 Figure 11 illustrates an exemplary embodiment of a disassembled buoyant panel according to Example 9, the perforatable membrane is shown in plan view, (A), and the buoyant frame is shown in plan view (B). Detailed Description of the Invention 30 Referring to all the drawings wherein like reference numerals designate like or corresponding parts throughout the several views. The following description refers to the WO 2010/031106 PCT/AU2009/001131 16 specific, illustrated embodiments of the present invention and is in no way intended to limit the scope of the present invention to those specific, illustrated embodiments. An assembled view of an embodiment of the buoyant panel 1 is shown in Figure 5. The 5. buoyant panel 1 for-use on a body of water comprises a buoyant perimeter frame 10 and a perforatable membrane 20 substantially located therewithin and substantially supported thereby, the frame 10 being constructed of a closed-cell foamed polymeric material having a substantially solid or hallow centre or a combination thereof. 10 Referring to Figure 1, the cross-section of a number of different possible profiles for the buoyant perimeter frame 10 is shown, which may be solid (A, B, C) or hollow with foamed walls (D, E, F). In certain embodiments of the present invention, the membrane/laminate 20 may 15 comprise an integrally bonded flat mat. Figure 2 shows an exemplary flat mat laminate 20 comprising a lower surface layer of bonded filler medium 100 and an upper surface layer 200 consisting of a UV-stabilised foil having perforations 205 of adequate strength to retain and support the bonded filler medium 100. 20 Figure 3 schematically illustrates three non-limiting examples of the types of materials that may be used for the membrane: A. woven open mesh fabric; B. spun-bonded (fused fibre) short fibre fabric; and C. perforated plastic- or Al-foil. In the case of the embodiment of the invention illustrated in Figure 2, the membrane is an 25 integral component. Several examples of various possible design options are shown in Figures 4 to 10 and these will be discussed further below. The simplicity of the design concept allows for many other geometrics should they be required. In particular, the invention is not to be limited to the ,quadrilateral-shaped panels illustrated herein. Buoyant panels of any shape can be constructed including, but not limited to, triangular, 30 pentagonal, hexagonal and octagonal.

WO 2010/031106 PCT/AU2009/001131 17 Specific embodiments and applications of the present invention will now be discussed in detail by reference to the accompanying example. This discussion is in no way intended to limit the scope of the invention. 5 Examples Example 1 - illustrated in Figure 4 The buoyant perimeter frame 10 is assembled from a selected profile, as illustrated in Figure 4, of strong and rigid configuration. The perimeter frame JO is stabilised with a cross-member 12 midway along the frame length. The membrane 20 is selected from 10 suitable material as shown in Figure 3 and wrapped around the length of the frame 10 and then jointed to form a tubc. The membrane is then stretched and separated from the upper side of the structure and.a profile bar 14 is inserted midway along the width of the perimeter frame 10 to form a slight apex to the membrane,- as shown in Figure 4A. The filler medium is inserted to a predetermined fill volume from the top end of the structure 15 and the membrane is then sewn up to form a complete enclosure, Example 2 - illustrated in Figure 5 Version 1 (Figure 5A and 5B) The buoyant frame 10 is assembled from a selected profile, as illustrated in Figure 1, of 20 strong and rigid configuration of approximately equal length to width ratio. The membrane 20 is selected from suitable material as shown in Figure 3 and which is sewn up to form a fillable pillow. The upper surface and the lower surfaces of the membrane may be made from different material types. The filler medium is inserted to the predetermined fill volume at the opening of the pillow and the pillow is then sown up to 25 form a complete membrane 20, The membrane 20 is stretched and fastened by cable ties 30 or plastic hooks to the buoyant perimeter frame 10 with as small a gap between the membrane 20 and frame 10 as possible. The fastening is positioned to achieve a uniform and stable structure. 30 WO 2010/031106 PCT/AU2009/001131 Version 2 In this non-illustrated version, the buoyant perimeter frame is enlarged by extending its length to two or three times its width. The panel extension is accomplished by producing two or three membranes of equal size. The profiles of the buoyant frame are extended to 5 an appropriate length. Cross-members are affixed at the end of each section to the frame structure. Version 2 has the advantage of providing greater stability due to the fact that it provides a larger area per panel and can be installed as interlocking patterns. Version 3 (Figure SC and 5D) 10 The buoyant frame 10 is assembled from a selected profile, as illustrated in Figure 1, of strong and rigid configuration of approximately equal length to width ratio. A flat panel is prepared as illustrated in Figure 2, wherein the membrane/laminate 100 is prepared with the membrane 200 extending past the edge of the laminate as shown in the cross sectional view of Figure 5D. This extended region 202 is positioned over the top of the 15 perimeter frame 10 and is used to link the membrane/laminate 100 to the frame 10 by welding. Example 3 - illustrated in Figure 6 Two plans of membrane of selected material, as shown in Figure 3, are sewn up as per 20 structure design as a pillow with sleeves for the insertion of the transverse perimeter frame members 1OT and cross-members 12 from a pre-cut selected profile as shown in Figure 1. The membrane 20 has initial side opening slots. The membrane material may be of different material type for the two sides of the pillow. The cross-members 12 and transverse frame members LOT are inserted into the sleeves of the membrane 20. The 25 filler medium is inserted to a predetermined fill volume at the opening of the pillow and the pillow is then sewn up to form a complete membrane 20. The longitudinal perimeter frame members lOT are then fastened to the transverse frame members 1OL and cross-members 12 to form the buoyant panel 1. 30 Example 4 illustrated in Figure 7 WO 2010/031106 PCT/AU2009/001131 19 The membrane of selected material, as shown in Figure 3,.is sewn up to form a pillow. The membrane material may be of different material type for the two sides of the pillow. The buoyant perimeter frame 10 is assembled from a pro-cut selected profile as shown in .Figure 1 of strong and rigid configuration. -The frame 10 is then inserted into the 5 membrane pillow. The filler medium is inserted to a predetermined fill volume at the opening of the pillow and the pillow is then sewn up to form a complete buoyant panel I with the perimeter frame 10 within the membrane 20. The fill fadtor can be chosen to produce a flat structure or a bulged structure. Cable ties 30 can be used to control the bulge of the structure. 10 Example 5 - illustrated in Figure 8 Two planes of membrane of selected material as shown in Figure 3 are sewn up as per structure design to form a longitudinal pillow with an opening at the long end of the pillow. The upper and lower surfaces of the membrane may be of different material 15 types. The filler medium is inserted to a predetermined fill volume at the opening of the pillow and the pillow is then sewn up to form a complete membrane 20. This process can be a continuous operation and then cut to unit length. The longitudinal perimeter frame members lOL from pre-cut selected profile, as shown in Figure 1, are fastened along the length of the pillow with cable ties 30 or plastics hooks. Transverse perimeter frame 20 members 10T and cross-members 12 are then fastened at determined spacings to the longitudinal perimeter frame members 1 OL to form the complete buoyant panel 1. Example 6 - illustrated in Figures 9 and 10 Version 1: 25 The buoyant perimeter frame 10 is assembled of selected profile, as shown in Figure 1, of strong and rigid configuration. The perimeter frame 10 is stabilised with.a cross-member 12 midway along the frame length. A further stabilising rod 14 is welded in the middle of the frame 10 in length direction. The membrane 20 is a bonded flat mat, such as shown in Figure 2 and is prepared to the size of the frame with overlap and recesses at the frame 30 junctions (Figure 9C). The flat mat, positioned with the membrane to the upper side, is then stretched and wrapped with overlap round the perimeter frame 10 and fastened by WO 2010/031106 PCT/AU2009/001131 20 appropriate fastening techniques, such as cable ties 30, adhesive or thermal welding. The flat-mat design may also consist of foam sheet being bonded to a woven or spun-bonded fabric. In this instance the design provides less evaporation suppression, but the ability to be planted with appropriate flora, 5 Version 2: The buoyant perimeter frame is assembled of selected profile, as shown in Figure 1, of strong and rigid configuration. The perimeter frame is identical to the frame of Figure 11 B. The membrane 20 is a bonded flat mat, such as shown in Figure 2 is prepared to the 10 size of the perimeter frame 10, or the sections of the frame, with overlap and recesses at the frame junctions. The flat mat positioned with membrane to the upper side, is then laid into the frame section with foil overlap fastened by appropriate fastening techniques such as cable ties 30, adhesive or thermal welding. 15 Example 7 - illustrated in Figure 6 The buoyant perimeter frame 10 in this instance is constructed of a circular closed-cell extruded profile as Figure IA, with a diameter size of 50mm. The core consists, in this instance, of LLDPE recyclates originating from 'agricultural foil', "silage wrap' or 'industrial shrink wrap'. The. profile is produced continuously by extrusion, whilst mixed 20 with a blowing agent. common to the art of producing closed cell extruded products of LLDPE type polymers. The preferred blowing of the profile in this instance is to produce a profile with a density of 0.45 kg/L. The buoyant perimeter frame members 10, and cross-members 12, are cut to lengths of 2 x 5.4 n and 4 x 1.8 m and recessed at their ends to facilitate maximum contact jointing. The members 10 are joined by thermal 25 fusion, to form a substantially rectangular frame, after being inserted into sleeves within the membrane 20. The membrane 20 in this instance consists of a woven fabric as shown in Figure 3A, close weave shade cloth of commercial grade with a density of approximately 220 g/m 2 , 30 preferably light coloured and UV stabilised to provide long-term water exposure and permeation, stability and sun exposure. The membrane 20 is cut to size to fit the inside WO 2010/031106 PCT/AU2009/001131 21 dimension of the buoyant perimeter frame 10, i.e. 2.0 m x 5.6 m providing allowance for sleeve stitching. The membrane fabric is stitched to form a pillow as described in Example 3 for retaining (i) the filler medium inside the pillow-like membrane; and (ii) the cross-members 12 inside the sleeves. The membrane 20 has cut-outs to coincide with 5 the junctions of the perimeter frame 10 (Figure 1 IA). After assembly, the pillow is stitched to form the membrane 20. The filler medium consists in this instance. of a mixture of the three types of material as described above in a ratio of 1:1:1. The filler medium has a material density of 0.075 10 kg/L and an open cell void factor (solid volume/void volume) of 0.25. The filler medium is predetermined to a volume of twice the perimeter frame 10 cavity volume. When the filler medium is inserted into the membrane pillow and distributed the resultant membrane 20 forms a flat configuration being in average approximately twice the thickness of the diameter of the frame profile, i.e. 100 mm. 15 The filled and completely sealed membrane 20 is secured to the buoyant perimeter frame 10 by insertion of the transverse perimeter frame members I OT in the outer slots of the membrane 20 prior to welding the longitudinal perimeter frame members 1OL and cross-members 12. 20 This buoyant panel I is suitable to be applied to the body of water. The panel 1 is suitable to be planted with plants either by incorporating the secds into the filler medium, sowing the seed evenly on top of the membrane or inserting plant cuttings or established plants through the shade mesh into the filler medium. 25 The buoyant panel 1 constructed according to this Example has the following dimensions and properties: Area of complete single panel: 9.720 M 2 30 Mass of complete single panel: 71,091 kg Length of frame profile: 18.000 m WO 2010/031106 PCT/AU2009/001131 22 Area of membrane fabric: 22.400 M 2 Volume of filler medium: 860 L. The buoyant panel 1 of this Example has a buoyancy to produce the following 5 characteristics: Total carry capacity per single panel: 229.0 kg Specific carry capacity: 23.6 kg/m2 % Immersion without payload: 23.7%. 10 Up-lift resistance (unplanted): 25.0 kg/n 2 . Example 8 - illustrated in Figures 9 and 10 The buoyant perimeter frame 10 in this instance is constructed of a circular closed-cell extruded profile as Figure 1A, with a diameter size of 50 mm. The core consists, in this 15 instance, of LLDPE recyclates originating from 'agricultural foil', 'silage wrap' or 'industrial shrink wrap'. The profile is produced continuously by extrusion whilst mixed with a blowing agent common to the art of producing closed-cell extruded products of LLDPE type polymers. The preferred blowing of the profile in this instance is to produce a profile with a density of 0.45 kg/L. The members of the buoyant perimeter frame 10, 20. profile bar 14 and cross-member 12, are cut to a lengths of 3 x 5.4 m and 3 x 1.8 m and recessed at their ends to facilitate, best contact jointing. The members are joined by thermal fusion to form a substantially rectangular frame 10. The membrane 20 in this instance consists of a polyethylene foil, 100 microns thick, 25 preferably light coloured and UV-stabilised to provide long-term water exposure, stability and sun exposure. The membrane is perforated with 10mm' diameter circular air vents at a rate of 25m-. A foam sheet of 20mm thickness consisting of granules of polyurethane foam, polystyrene granules in the ratio of 3 to 1 bonded together with a polymeric binder heat bonded to the polyethylene film membrane to form the membrane 30 20. The membrane 20 is cut to size to fit the design of the buoyant perimeter frame 10 (i.c. 5.6 m x 2.0 m). The membrane 20 is recessed on the comers and at the fastening WO 2010/031106 PCT/AU2009/001131 23 points of the frame member 10 as shown in Figure 9C to facilitate the overlapping of the membrane 20 around the buoyant perimeter frame 10. The membrane 20 is positioned on top of the assembled frame 10, with the membrane 20 being on the opposite side of the frame 10, and secured to the frame 10 by lapping the outside flaps of the membrane 20 5 around the perimeter frame members 10. The securing of the membrane 20 in this instance is by fastening the flaps (not shown) to the membrane 20 with commercially available UV-stabilised plastic cable ties 30 in spacing's gap to ensure permanent fixture of the membrane 20 to the perimeter frame 10 as shown in Figure 1 OA. 10 The buoyant panel 1 constructed according to this Example has the following dimensions and properties: Area of complete single panel: 9.7 m 2 Mass of complete single panel: 29.0 kg 15 Length of frame profile: 18.0 m Area of membrane fabric: 19.5 in 2 Volume of filler medium: 200 L. The buoyant panel 1 of this Example has a buoyancy to produce the following 20 characteristics: Total carry capacity per single panel: 18.0 kg Specific carry capacity: 1.8 kg/r 2 Up-lift resistance (unplanted): 22.0 kg/m 2 25 Example 9 - Typical method of preparing a buoyant panel (See Figure 11). Bnoyant Frame A semi-rigid buoyant perimeter frame 10 isproduced from rods of recycled polyethylene and other Isuitable polyolefin scrap plastics by conventional extrusion techniques and 30 formed into a 50mm diameter circular cross-section using a sizing die former. A blowing WO 2010/031106 PCT/AU2009/001131 24 agent (azodicarbamide). is incorporated into the extrusion of the plastic mixture to produce a closed-cell foamed rod. The bulk density of the rod is 0.65 g/cxn, Rods are cut to the desired lengths of 2.7m for the longitudinal perimeter frame members 5 10L of the panel and 0.8m for the transverse perimeter frame members lOT and cross-members 12. During assembly, the rods are heat welded together using a conventional plastics butt-welding technique, A clamping frame is used to maintain pressure on the welded joints until they cool. 10 Membrane A filler-retaining membrane 20 comprised of lightweight commercial shadecloth (50% shade factor) is separately fabricated. A 2.7m length of I.8m wide shadecloth is folded over itself with an overlap of 100mm. The overlap is formed on the top of the membrane. The material is then sewn into a pattern to produce two sleeves or pockets on the long 15 side of the panel and four sleeves across the panel to produce three sections of equal size. Each section has an opening formed by the overlapping shadecloth. Sections of the sleeves are cut away to form open sections to allow heat welding of the frame as shown in Figure I lA. 20 Filler Medium A mixture of three components is used for the filler medium: 50% by volume of chips of expanded polystyrene. 25% by volume of chips of polyurethane (PU) flexible foam. 25% by volume of shredded carpet. 25 The three components are mixed, together to form a homogeneous blend prior to inserting into the inner membrane bag consisting of biodegradable plastics foil. The bag is beat sealed after insertion of filler. 30 Assembly of Buoyant Panel WO 2010/031106 PCT/AU2009/001131 25 Assembly consists of inserting the pre-cut rods into the sleeves of the shade cloth membrane 20 in the configuration shown in Figure 11B. While being held in a clamping frame, the transverse perimeter frame members 10T and cross-members 12 are heat welded to the inside of the longitudinal perimeter frame members 1OL. Clamps are used 5 to provide pressure on the heat welded joints until the weld has cooled and set. An 8 mm hole 16 is drilled vertically through the centre of the longitudinal perimeter frame members I OL opposite each heat weld. The purpose of the holes- 16 is to permit tethering of the panels at the time of installation. 10 A filler bag is placed in each section of the panel by inserting through the opening of the shadecloth pillow sleeve. Filler is then manipulated to achieve approximately equal thickness across the whole panel section. Plastic canoe clips, or the like, are pushed through the two overlapping pieces of shadecloth (pillow sleeve) to effect closure. The filling operation may take place at the time of assembly or subsequently at the site of the 15 installation. The filler bag must be perforated after the pillow membrane 20 is closed, to allow ingress of water, the perforating process preferably taking place during the installation of the panels. The earlier disadvantages detailed in relation to previously known buoyant panels can be 20 minimized or at least substantially ameliorated by the present invention. Accordingly, in various'embodiments, the panel of the present invention finds application in a number of areas including: (i) as artificial islands hosting plants, wherein the plants are useful in water treatment; (ii) as artificial islands hosting plants, wherein the plants 25 are useful in providing bird nesting habitats and/or protective shelter for fish and crustaceans; (iii) as artificial islands hosting plants, wherein the plants are used for beautification of the environment; (iv) for evaporation control; and (v) for wave damage control. 30 Where the terms "comprise", "comprises", comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, WO 2010/031106 PCT/AU2009/001131 26 integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component br group thereof. Whenever a range is given in the specification, for example, a composition or 5 concentration range, all. intermediate ranges and sub-ranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. One of ordinary skill in the art will appreciate that materials and methods, other than those specifically exemplified can be employed in the practice of the invention without 10 resort to undue expcrimehtation. All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it 15 is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by examples, preferred embodiments and optional features, modification and variation of the concepts lierein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within 20 the scope of this invention as defined by the appended claims.

Claims

1. A buoyant panel for use on a body of water, the panel comprising a buoyant perimeter frame and a perforatable membrane substantially located therewithin and 5 supported thereby, the frame being constructed of a closed-cell foamed polymeric material having a substantially solid or hollow centre or a combination thereof.

2. The buoyant panel of claim 1, wherein the membrane is a pillow-like structure and comprises filler medium within the membrane.

3. The buoyant panel of claim 1 or 2, wherein the buoyant perimeter frame member is 10 constructed from foamed polyethylene or composites of polyethylene.

4. The buoyant panel of claim 3, wherein the buoyant perimeter frame member has density of approximately 0.45 to approximately 0.75 g/cm

5. The buoyant panel of any one of claims 1 to 4, wherein the membrane comprises a porous and/or woven material or perforated plastic- or Aluminium foil. 15

6. The buoyant panel of claim 5, wherein the membrane is selected from woven open mesh fabric or spun-bonded short fibre fabric.

7. The buoyant panel of claim 6, wherein the membrane is shadecloth.

8. The buoyant panel of claim 5, wherein the membrane comprises perforated Aluminium foil. 20

9. The buoyant panel of claim 1, wherein the panel is a flat-mat and comprises filler medium adhered to the membrane.

10. The buoyant panel of claim 9, wherein the membrane comprises perforated Aluminium foil.

11. The buoyant panel of any one of claims 1 to 10, wherein the buoyant perimeter 25 frame member is constructed from foamed polyethylene or composites of polyethylene.

12. The buoyant panel of claim 11, wherein the buoyant perimeter frame member has density of approximately 0.45 to approximately 0.75 g/cm 3 . 27

13. The buoyant panel of any one of claims 1 to 12, wherein the filler medium is selected from any one or more of the following: (i) bonded or non-bonded closed-cell foam chip; (ii) bonded or non-bonded open-cell foam chip; and 5 (iii) shredded fabric/carpet and/or plastics granules/flakes.

14. The buoyant panel of any one of claims 1 to 13, wherein the filler medium is further bonded by an adhesive to retain a coherent water pervious structure.

15. The buoyant panel of any one of claims 1 to 14, when used in the formation of a floating biosphere comprising a plurality of buoyant panels. 10

16. The buoyant panel of any one of claims 1 to 15, substantially as hereinbefore described with reference to any one of the accompanying Figures or Examples.