AU595542B2

AU595542B2 - Holding tanks

Info

Publication number: AU595542B2
Application number: AU62828/86A
Authority: AU
Inventors: Michael Graeme Hanrahan
Original assignee: Austmarine Pty Ltd
Current assignee: Austmarine Pty Ltd
Priority date: 1985-08-20
Filing date: 1986-08-20
Publication date: 1990-04-05
Anticipated expiration: 2006-08-20
Also published as: WO1987001010A1; JPS63501472A; JPH0728629B2; AU6282886A

Description

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AU-AI 6 2 8 2 8 86 WORLD INTELLECTUAL PROPERTY ORGANIZATIO INTERATI L A ATInternationaDl aN QE4TI

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INTERNATIONAL APPLICATION PUBLISHED UND I A T PEATIFREATY (PCT) r (51) International Patent Classification 4 (11) International Publication Number: WO 87/ 01010 A01K 63/00, 63/02, 63/04 Al (43) International Publication Date: 26 February 1987 (26.02.87) A01K 63/06 (21) International Application Number: PCT/AU86/00242 Published With international search report.

(22) International Filing Date: 20 August 1986 (20.08.86) (31) Priority Application Number: PH 2043 -r.

(32) Priority Date: 20 August 1985 (20.08.85) (33) Priority Country: AU 3 (71)(72 SECTION 34(4)(a) DIRECTION SEE FOLIO l NAME DIRECTED AAS I- Pl 1 (74) Ag

AUSTRALIAN

(81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (European 10 MAI 1987 patent), FR (European patent), GB (European patent), IT (European patent), JP, LU (European pa- PATENT' OFFICE tent), NL (European patent), SE (European patent),

US.

TiB' documant (axtalsa ie a a~denets made ular (54) Title: HOLDING TANKS 208 209 an to W" 1w VeW s.

1, 203---i 207- 216 (57) Abstract Apparatus for use in maintainin, aquatic animals in a gsate of hibernation. The apparatus is of the type comprising a holding tank (200) to contain the water environment, a horizontal, perforate partition (507) above the floor of the tank, a particulate filter bed (508), (509) supported on the partition and extending to the walls, the filter bed bearing a culture of denitrifying bacteria, and a water conditioning circuit. The water conditioning circuit has two sections, a first circuit having a circulation pump (206), a water cooling device (213), an activated carbon filter (214) and a water-returning spray assembly (208) and a second circuit incorporating a skimmer assembly (211). The first circuit is to draw water to be conditioned from beneath the partition and to turn the conditioned water to the tank. The skimmer is a vertical tube, open at its upper end, the upper end being near the surface of water contained in the tank, the lower end being, in communication with the first circuit upstream of the pump and the carbon filter via a conduit, the skimmer assembly being isolatable from the first circuit by a valve located on the conduit.

1A "HOLDING TANKS" This inv-ntion relates to a receptacle or holding tank for live fish, crustacea and other aquatic organisms, and also, to a method of using this receptacle for storing, maintaining, revitalising, hibernating and/or breeding these aquatic organisms.

Numerous receptacles have been proposed for use with live aquatic organisms, but they have all suffered from various problems which have limited their usefulness, particularly in relation to keeping commercial quantities of live aquatic organisms, such as in restaurants.

Several portable receptacles have been proposed for use primarily in transporting live crustacea. One such receptacle is provided by United States Patent no. 2286146 which describes a sealable insulated box adapted to contain an aquatic medium for holding the crustacea. The aquatic medium includes a substantial quantity of water which is refrigerated by using an ice receptacle, and the water is circulated through a simple cartridge-type filter. This receptacle has several problems in that the box must be opened to view the crustacea, and it is not possible to accurately control the temperature of the water. Also, the filter does not adequately remove various toxins such as nitrates, which are created by the decomposition of the crustacea's faeces. Hence, this type of receptacle can only be used for very short term storage of the aquatic organisms.

a1 TE .1 2 An improved version of the receptacle described above is provided by U.S. patent no. 4089298. In this receptacle, the crustacea are carried separately in a multiplicity of individual containers which are supported within a sealable insulated box.

This receptacle contains a minimum quantity of water which is sprayed over the individual containers and allowed to percolate downwards through holes in the containers. The water is refrigerated by a conventional refrigeration unit that is contained within the receptacle, and toxins, etc are removed from the water by a chemical process. The main problems with this receptacle are that the box must be opened to view the crustacea, and that the chemicals for treating the toxins must be continually topped up if the receptacle is to be used for any reasonable period of time.

Several other receptacles have been proposed which include a tank having one or more transparent walls so that the receptacle can be used to display the aquatic organisms in restaurants, or other places. All of these receptacles include a refrigeration circuit for cooling the aquatic medium to a suitable temperature somewhere in the range of 27°C, depending on the type of organism being kept.

One such receptacle is described in U.S. Patent no.

2594474 which provides a receptacle having a water filtration circuit to remove all solid impurities from the water. This 3 filtering is performed by a plurality of fine filters comprising sponge-rubber material and/or very fine particulate material. The water is also Limically treated to remove toxins, etc, and is aerated using venturi device.

The main problems with this receptacle are that the fine filters are easily clogged by the fine sediments, etc which are present on crustacea when first caught, and the water quality must be continually monitored to ensure that the toxins are being removed. Furthermore, the venturi does not aerate the water sufficiently to allow the receptacle to support a large population of crustacea. These problems all increase the operating costs for this receptacle.

A similar receptacle is provided by U.S. Patent No.

4202291 which also uses chemical treatment of the water to remove toxins. Also, the water refrigeration circuit cools the water to such a low temperature, that the aquatic organisms are barely alive and are effectively immobilised.

While this amount of cooling reduces the organism's metabolic rate to an absolute minimum to sustain life, and hence reduces the output of faeces, it alrl makes the organisms appear "dead", and so they may not appeal to the patrons of the restaurant for example. Furthermore, the cost of cooling the water becomes a significant part of the operating costs of the receptacle, and may make the operation of the receptacle uneconomic.

Australian Patent Application no. 36788/68 and i~rmmmJ1 -~v similar U.S. Patent no. 3387587 provide a receptacle which includes a bio-chemical filter to treat the water. The biochemical filter comprises coarse grains of coral, for example, which have a grain size of 2mm 5mm and which house a culture of denitrifying bacteria. The bacteria process the nitrates generated by faeces, etc, while the coral grains react chemically to maintain a predetermined alkalinity in the system. In this way, the quality of the water is maintained within suitable limits by circulating the entire quantity of water through the filter four times an hour.

This receptacle has several problems in that the biochemical filter can not always treat the water properly since the grain size is too big to allow an adequate culture of bacteria to grow, and the water can not be circulated through the filter at a high enough rate to allow the bacteria culture to fully process the nitrates without destroying the culture. Also, the filter utilises a foam pre-filter which is easily clogged. Hence, this type of receptacle requires a lot of maintenance to clean the pre-filter, and the water also requires chemical treatment to compensate for the inadequacies of the bio-chemical filter. These deficiencies increase the operating costs of the receptacle, and also reduce its carrying capacity with respect to the aquatic organisms.

United Kingdom Patent no. GB1495764 provides a receptacle which uses a biological filter to treat the water.

LL 3 r I-i i- This biological filter comprises a layer of particulate material, such as sand or crushed coral, which supports a culture of denitrifying bacteria. GB1495764 further provides a plankton culture which survives in the water and assists the bacteria culture in processing the water. Also, the filter of GB1495764 is of variable thickness since it is supported by a corrugated porous panel. These features of GB1495764 mean that the water must be circulated very slowly through the filter, otherwise the plankcton and/or the bacteria will be destroyed. This slow rate of water circulation means that the carrying capacity of the receptacle is severely limited for a given size of receptacle.

Lastly, U.S. Patent no. 3855970 provides a receptacle having biological filter of substantially constant thickness. However, this receptacle does not include any means for aerating the water apart from the absorption of oxygen from the atmosphere. This comparative lack of oxygen in the water severely restricts the effectiveness of the bacteria culture in breaking down waste products, and thus, reduces the carrying capacity of the receptacle.

A further problem common to each of the above receptacles which contain an aquatic environment is that they do not have provision for removing floating solid materials or scum. This scum is normally formed from organic material such as food particles, faeces, etc, and contributes to the .e 6 formation of ammonia within the aquatic environment as each of the above receptacles have the water removed from the bottom of the receptacle for filtering, etc, this scum is usually removed manually.

It is an object of the invention to provide a receptacle for sustaining live aquatic organisms which substantially alleviates at least some of the problems of the prior art receptacles discussed above.

According to one aspect of the invention there is provided a receptacle for sustaining live aquatic organisms in an aquatic environment, said receptacle including: S fIlter means for processing waste products produced by said organisms, said filter means being adapted to fit within said receptacle; water conditioning means for circulating water contained in said aquatic environment through said filter means and regulating the temperature of said water, said conditioning means comprising a pumping means, a cooling means, and a spray means, whereby said pumping means draws water from said receptacle through said filter means and returns said water to said receptacle via said cooling means and said spray means; and a skimmer means for removing floating scum material from said aquatic environment, said skimmer means being said water conditioning means and including an inlet located at or just below the operative level of water I~ 7 within said receptacle whereby water entrained with said vrpA Vr xqt Yr- 4 pC fiteedfkod andfloating scum material may be filtered and thereafter returned to the aquatic environment by the action of said pumping means via said spray means; wherein in use, sai& water spray means breaks up said floating scum material into small pieces which may be collected by said skimmer means and thereby removed from said aquatic environment.

The filter means may comprise a layer of particulate material supporting a culture of denitrifying bacteria, wherein said filter means covers at least part of a floor portion of said receptacle. Suitably the layer of particulate material is of constant thickness and maybe supported in a spaced relationship above the floor portion by a porous support means. Preferably the support means substantially covers the floor portion of the receptacle.

Advantageously the porous support means comprises an inverted perforated tray.

Suitably, the layer of particulate material comprises a plurality of sublayers located one atop the other. Preferably each sublayer comprises particulate material having a generally similar particle size, with different particle sizes for each sublayer. Advantageously, the sublayers are arranged in increasing particle size with the finest particle size adjacent the tray and the coarsest particle size remote from the tray. Desirably the particulate material comprises shellgrit material, having a particle size of between 0.5mm and Suitably, the water conditioning means circulates the entire volume of water contained within the receptacle through the biological filter means between 4.0 and 7.5 times per hour.

The cooling means may comprise a refrigeration means. Suitably the refrigeration means includes an evaporator contained within a housing assembly. Preferably the evaporator comprises a length of tubing coiled in a serpentine manner. Advantageously the water to be cooled passes through the housing assembly and over the coiled tubing, whereby the water is cooled. Desirably the cooling temperature may be regulated by a thermostat.

Suitably the spray means is located above the operative level of water contained within the receptacle.

Preferably the spray means comprises one or more tubular manifolds having at least one hole therein for spraying water. Advantageously each manifold includes a plurality of holes therein for spraying water.

The skimmer means may be connectable to the water conditioning means by a valve means. Suitably, the valve means may comprise a normally shut valve means. Preferably the valve means is a ball valve. Advantageously the skimmer means comprises skimmer assembly and a filter assembly. It is preferred that the skimmer assembly be adjustable to suit 0 1Anf I 9 different operative levels of water within the receptacle.

Desirably the skimmer assembly comprises a telescoping tube assembly. It is also preferred that the filter assembly include an activated carbon filter. Suitably, the activated carbon filter is in the from of a replaceable cartridge.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings wherein: Fig. 1 depicts a cross-sectional view of a receptacle according to the present invention; Fig. 2 depicts an enlarged detail view of the skimmer assembly of Fig. 1; Fig. 3 depicts an enlarged detail view of the manner of construction of the receptacle of Fig. 1; Fig. 4 depicts a schematic view of the cooling means of the receptacle of Fig. 1; Figs. 5(A) and 5(B) depict details of the refrigeration means of the cooling means of Fig. 4; Fig. 6 depicts a part cross-sectional view of the filter assembly of the skimmer means of Fig. 1; and Fig. 7 depicts an alternative filter assembly to that depicted in Fig. 6.

SReferring to Fig. 1, there is depicted a receptacle or tank 200 holding an aquatic environment comprising a body of water 201 and a layer of particulate material or shellgrit 202 to act as a biological filter means. Shellgrit 202 is v -0

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supported by a support means or inverted perforated tray 217 so as to provide a water chamber 203 between the layer of shellgrit 202 and the floor portion of tank 200. Shellgrit 202 also carries a culture of denitrifying bacteria which processes the wastes, e.g. faeces, produced by the aquatic organisms (not shown) living in water 201.

The water conditioning means associated with tank 200 comprises pump 206 which draws water 201 from tank 200 through shellgrit 202 and into chamber 203. From chamber 203, water 201 passes through pipe 204 into cooling means or refrigeration unit 213, then through pump 206 and into spray means or water spray manifold 208. Manifold 208 returns water 201 to the tank 200 in the form of a water spray 209, located approximately 25mm above water 201 and which breaks the surface of the water as shown at 210, so as to thereby aerate the water. Water spray 209 also breaks up any floating scum material (not shown) into small pieces which may be removed by skimmer 211. A pair of valves 215 are provided to control the flow of water through the water conditioning means. Valve 216 can be used as a drain cock if required.

Pump 206 is capable of circulating the entire body of water through the water conditioning means between 4.0 and times per hour. This flow of water together with the vigorous aerating of the water provided by manifold 208 enables shellgrit 202 to carry a dense culture of v- I 11-~.~1-~~1'-'-1111~1111 denitrifying bacteria which is much denser than the bacterial colonies or cultures provided by the prior art rGceptacles discussed previously. Hence the carrying capacity of tank 200 is much larger than for similar sized prior art tanks.

Also provided in Fig. 1 is a skimmer means 211 which removes scum (not shown) from the surface of water 201, as described above. Skimmer 211 is connected to a filter assembly 214 by pipe 212 and is connectable to the water conditioning means through valve 215 and T-joint 205 which connects into the water circuit upstream of pump 206. A further valve 215 is provided in pipe 212 to control the flow of water through skimmer means 211, so as to control the rate of removal of the floating scum material.

Skimmer means 211 is described in detail in Fig. 2.

In Fig. 2, there is shown tank 300 which has a vertical pipe 301 passiLg through the base thereof and sealed at 302 by a suitable seal. A second pipe 303 of smaller diameter than pipe 301 is telescopically slidable within pipe 301, with the annular space between pipes 301 and 303 sealed by an O-ring seal 304. This construction allows the skimmer to be height adjustable and so suit different operative levels of water 305 contained within tank 300.

The typical construction of tank 200 is depicted in Fig. 3. Double glazed panelling is employed with outer and inner panels 501 and 502 respectively, sealed to a base sheet 500. Panels 501, 502 are also sealed at 503 by a glass bar i 12 so as to provide an enclosed volume of air 504, and a quantity of desiccant such as silica gel 506 is used to dry the air and prevent condensation occurring on panels 501, 502 which may be caused by cooled body of water 505. An inverted perforated tray 507 made from a P. V. C. material rests on base 500 and supports a multilayered shellgrit bed formed from fine particles 508, and coarse particles 509. The tank may be illuminated by an overhead light 510 located in a reflective shield 511, also typically constructed from P. V.

C. material.

Referring to Fig. 4, there is schematically depicted a cooling means for use with the tank of Fig. 1.

This cooling means is found to be appropriate for tanks of typically 400 litre (90 gallon) capacity which are suited for use in a restaurant. The cooling means utilises a refrigeration system employing a capillary expansion system.

In Fig. 4, the output of compressor 100 feeds refrigerant by pipe 101 to a condenser 102, and from there, the refrigerant is carried by pipes 103 and 105 through drier 104 to a capillary expansion unit 106. From expahsion unit 106, the refrigerant enters evaporator 107 and returns to compressor 100 via pipe 108.

Evaporator 107 is described in more detail in Figs.

and Fig. 5(A) is an end view of the front of the evaporator, while Fig. 5(B) is a side view. The evaporator is housed in a housing assembly constructed from a length of

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1 1. 1 1-1 11- 1.1 1 11.1. 11-11 l Z+ I cylindrical pipe 700 sealed at each end by end plates 701 and 702. Typically, pipe 700 is formed from a 250mm or 320mm length of P. V. C. tube, and the end plates 701 and 702 are hot air welded to pipe 700. End plate 701 is provided with an inlet 708 and outlet 709 for an evaporator coil 712 which is located within the housing assembly. Coil 712 is typically formed from a length of copper tubing which has been coated with a suitable epoxy re-in such as Dulux Powderkote Epoxy Resin. This epoxy coating restricts corrosion of coil 712 when used in a saline environment. Housing assembly is also provided with an inlet 711 and outlet 710 through which the water to be cooled is circulated.

A thermostat probe 706 is also provided to regulate the cooling temperature of the water. Probe 706 is inserted through end plate 701 and is connected via a capillary line 705 to a thermostat control 704. A mounting plate 703 may also be provided to enable the housing assembly to be mounted in any convenient position.

In Fig. 6 is shown the components employed in setting up a filter assembly or protein filter cartridge used in conjunction with the skimmer assembly. A housing 601 is provided with an inlet 602 and outlet 603. The inlet 602 leads water into housing 601 and on into a compartment 605 filled with activated carbon. Compartment 605 is divided off from a central passageway leading to outlet 603 by a perforated wall such as may be formed by a perforated PVC Ti 1_ 14 pipe. The perforations serve to allow water to flow therethrough whilst retaining the activated carbon in compartment 605. The cartridge is conveniently constructed with a screwed lid at 606 so that the cartridge may be opened, emptied, and recharged whenever the activated carbon is required to be changed. In order to enable this, the inlet and outlets are preferably connected to the inlet and outlet lines by disconnectable junctions with valves which may be closed to cut off the lines prior to disconnection.

As with other components employed with the holding tank, the filter cartridge is constructed from non-corrodible materials. The presently set out filter structure is suited to the smaller, restaurant type tanks. In larger holding tanks, larger activated carbon filters may be required so as to handle larger volumes of waste.

Fig. 7 shows the layout of a protein filter which can be used for large holding tanks. A box 900 is split into two compartments 901 and 902 by a baffle 903 which reaches almost to the bottom of the box to retain a charge of activated carbon 904 in compartment 901. Water to be cleaned is fed in at inlet 905 to compartment 901, to diffuse downwardly through the activated carbon bed 904 beneath baffle 903 to compartment 902 and out via outlet 906.

While the above has been given by way of example, many modifications and variations may be made to the invention by persons skilled in the art. Large tanks, for I L l I I example, may be provided by joining together several smaller tanks which effectively create a partitioned body of water, with each smaller tank being similar to the tank described above.

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Claims

1. A receptacle for sustaining live aquatic organisms in an aquatic environment, said receptacle including: biological filter means for processing waste products produced by said organisms, said filter means being adapted to fit within said receptacle; water conditioning means for circulating water contained in said aquatic environment through said filter means and regulating the temperature of said water, said conditioning means comprising a pumping means, a cooling S* means, and a spray means, whereby said pumping means draws water from said receptacle through said filter means and returns said water to said receptacle via said cooling means and said spray means; and skimmer means for removing floating scum material from said aquatic environment, said skimmer means being isolatable from said water conditioning means and including an inlet located at or just below the operative level of water vithin said receptacle whereby water entrained with said floating scum material may be removed from said receptacle and filtered and thereafter returned to the aquatio environment by the action of the pumping means via said spray means; wherein in use, said spray means breaks up said floating scum material into small pieces which may be collected by said skimmer means and thereby removed from said aquatic environment. rAPn v c 17

2. A receptacle as claimed in claim 1 wherein the filter means comprises a layer of particulate material supported in a spaced relationship above a floor portion by a porous support means.

3. A receptacle as claimed in claim 2 wherein said support means substantially covers said floor of said receptacle.

4. A receptacle as claimed in claim 2 or claim 3 wherein said support means comprises an inverted perforated tray.

A receptacle as claimed in any one of claims 1 to 4 wherein said filter means comprises a layer of particulate material supporting a culture of denitrifying bacteria, wherein said filter means covers at least part of a floor portion of said receptacle.

6. A receptacle as claimed in claim 5 wherein said layer of particulate material comprises a plurality of sublayers of particulate material located one atop the other.

7. A receptacle as claimed in claim 6 wherein said sublayers are arranged according to particle size with the sublayer having the finest particle size located adjacent said support means and the sublayer having the coarsest particle size located remote from said support means.

8. A receptacle as claimed in any one of claims 1-7 wherein said water conditioning means circulates the entire 18 volume of water contained within said receptacle through said filter means between 4.0 and 7.5 times per hour.

9. A receptacle as claimed in any one of claims 1-8 wherein said cooling means comprises a refrigeration means.

10. A receptacle as claimed in claim 9 wherein said refrigeration means includes a thermostat for regulating the refrigeration temperature.

11. A receptacle as claimed in any preceding claim wherein said spray means is located above the operative level of water contained within said receptacle.

12. A receptacle as claimed in claim 11 wherein said water spray means comprises one or more tubular manifolds having at least one hole therein for spraying water.

13. A receptacle as claimed in any one of claims 1-12 wherein said skimmer means is connected to said water conditioning means by a normally shut valve means.

14. A receptacle as claimed in claim 13 wherein said skimmer means comprises a skimmer assembly and a filter assembly.

15. A receptacle as claimned in claim 14 wherein said skimmer assembly comprises i telescoping tube assembly adjustable to suit different op, 'ative levels of water within said receptacle.

16. A receptacle as claimed in claim 14 wherein said filter assembly includes a replaceable activated carbon filter cartridge. TEA (7. I

17. A receptacle for sustaining live aquatic organisms in an aquatic environment substantially as hereinbefore described with reference to the accompanying drawings. DATED this twenty-fourth day of November 1989 MICHAEL GRAEME HANRAHAN By his Patent Attorneys G. R. CULLEN CO. SO J rr- L.