Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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I¦ Field of the Invention
il This invention relates to aquaculture systems and more par-
ticularly to a method and apparatus for flushing an aquaculture
¦tank so as to effect settled waste removal with the least loss of
5 llculture water and without the necessity of removing the animals 5
from the tank.
~ackground of the Invention
~ Aquatic animals and more particularly, crustaceans such as
¦lobsters, have been raised in habitats which, in general, are
¦arranged so as to keep the animals separated. The animals must
lO Ibe separated because of their carniverous nature which can result ¦10
in death or, at the very least, injury through which bacterial
infection can enter the body.
Studies of raising such animals in separate compartments or
cages within a habitat show that, while physical separation indeed
increases the yield, a more common cause of the untimely demise of 15
an animal is disease. In order to control disease, it has been
found that a constant flow of filtered and aerated water reduces
disease significantly. However, it has been found that bacteria
which thrive on the waste due to uneaten food and excreta,and
ammonia and other byproducts of the decay thercof,are as detri- l20
mental to animal health as any other known factor. It is there-
¦ fore important in an aquaculture system to clean the habitats aswell as filter the aerated water supply to the habitats.
~1 Under ordinary circumstances, when, for instance, the habitatls
251 are in the form of cages immersed in a tank of water, it is commonii 25
to remove the cages, scrub the tank and then replace the cages
¦ and fill the tank with water again. This, of course, subjects the
animals to the trauma of being removed from their aquatic medium
and is an extremely time-consuming process.
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On the other hand, it has been found that the tanks can be
exceptionally well cleaned without the removal of the animals and
without lowering the water level of the tanks to a point at which
any animal is not immersed in water. The subject system involves
5 Ithe utilization of a tapered bottom member for the tank, which 5
in a preferred embodiment, is funnel-shaped. The discharge port
of the funnel is provided with a fast-closing valve which is
double pulsed or actuated so as to first dislodge the waste which
l;has accumulated at the sides and bottom of the funnel and concen-
10 l,trated it into a small region immediately above the valve. On thell0
second pulse or actuation the valve is again opened so as to dis-
charge the concentrated waste slurry. In one embodiment to be dis-
cussed hereinafter, it has been found that only two quarts of
l water are utilized in the flushing process, out of 45 gallons in
the tank. In the configuration described, the entire flushing 15
process involves only a one-inch water drop and make up water is
easily provided.
The double pulse actuation of the valve, at least on the first
~ valve opening and closing, produces a small but effective turbulent
wave front which dislodges the wastc material which has settled to 20
the funnel-shaped bottom of the tank. This turbulence is entirely'
within the funnel and below the animals. In one embodiment, the
fast-closing valve utilized is a poppet type valve, which when the
valve-is deactuated, snaps back into the valve seat very quickly
due to the rather large column of water above the valve. ~'hen 25
~ opening the valve, it is not particularly important that it be
,lopened quickly, but when the valve is closed, it is necessary that
l! it close rapidly so as to produce the turbulent pulse for di~lodging
the waste material. The tapered configuration of the bottom of
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the tank contributes to the concentration of the waste material in
a small area adjacent to the valve, such that when the valve is
lopened for the second time this waste material is discharged quickly
jland with a minimum of water loss.
5 ~ It will be appreciated that the tapered construction of the 5
bottom of the tank may take on a variety of forms such as truncated
pyramids, funnel-shaped devices, or even hemispherical bottom shapes.
As such, the subject invention is not limited to any particular
~Itype of tapered bottom member.
10 ll It will be appreciated that with the double pulsed flushing 10
l¦method and apparatus, the animals are never deprived of their aqua-,
¦Itic medium and are not subjected to the trauma of being removed
from the tank. Moreover, it has been found, that an exceptionally,
efficient cleaning of the tank is accomplished with a minimum of
water loss which adds to the efficiency of the aquaculture system.ll5
It is also a finding of this invention that this type of cleaning ¦
is all that is necessary with respect to the solid waste material
which is heavy enough to drop to the bottom of the tank. This is
because, at least in the case of lobsters, the animals clean theirl
20l cages themselves. Of course, if the water provided is pumped from¦Z0
the base of the tank to the top of the tank where it overflows,
some of the waste material which is more buoyant in nature or has I
been carried upward by the air-lift pump action of the aerator can¦
be skimmed off from the top of the tank. Thus, the system des-
cribed herein relates primarily to waste material which is heavy l25enough to settle to the bottom of the tank despite water and air
~ flow in an upward direction in configurations so equipped. It will
¦~be appreciated that if this waste material is allowed to collect
l¦at the bottom of the tank where the water is introduced, bacteria
30¦~from the waste may be carried upward and infect the animals causing30
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severe health problems. Thus, it is a feature of the
subject invention that tanks may be regularly cleaned as
many times a day as necessary without a large expenditure of
time or loss of water which results in energy savings in
view of the fact that water in the tanks is usually heated.
It is, therefore, an object of this invention
to provide an improved flushing system for an aquaculture
rearing tank;
It is another object of this invention to provide
a double pulsed flushing system in which the quick closing
of a dump valve produces a turbulent pulse in the base of
a tank sufficient to break up accumulated wastes without
danger to the animals;
It is another object of this invention to provide
a cleaning method for an aquatic animal rearing tank in
which exceptionally efficient cleaning is achieved with
a minimum of water removal,
It is a still further object of this invention to
provide a method and apparatus for the cleaning of an aqua-
culture tank in which the animals within the tank need not
be removed in order to effectuate cleaning.
In one aspect of the invehtion there is provided
a method of maintaining animal health in an aquaculture
habitat in which the habitat includes a tank for water,
comprising the steps of: providing a tapered base for the
tank, the base having a discharge port at the tapered end
and a dump valve at the discharge port; opening said valve
and closing it quickly so as to produce a local turbulent
pulse to dislodge waste within said tank base; and reopening
said valve for a short additional period sufficient to
permit discharge of the dislodged waste, whereby animal
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health is maintained by efficient habitat cleaning with a
minimum of water removal and trauma to the animals.
In a further aspect of the invention there is
provided a method of minimizing water loss in the flushing
and cleaning of an aquaculture habitat which includes a
tank for water, comprising the steps of: providing the tank
with a tapered base having a discharge port at the tapered
end; providing a valve at the discharge port; and double
pulsing said valve so as to open it twice, the first opening
and closing to provide a local turbulent pulse for dis-
lodging waste material in the tank and for consolidating
it at the discharge port; and the second pulse reopening
said valve for a time sufficient to remove the consolidated
waste at the discharge port, whereby a minimum of water is
lost in the process and whereby the water level in the tank
need not drop sufficiently to expose any animal within
the tank.
In another aspect of the invention there is provided
an apparatus for maintaining animal health in an aqua-
culture habitat which includes a tank, comprising: atapered base for said tank, said tapered base having a
discharge port at the tapered end; and means for compacting
waste material at the base of the tank in a region immediately
above said discharge port and for discharging the compacted
waste, said means including a valve, and means for opening
said valve and closing said valve quickly and then reopening
said valve for a sufficient time to effect removal of the
compacted waste.
In still another aspect of the invention there is
provided an apparatus for minimizing water loss in the flush,
ing and cleaning of an aquaculture habitat which includes
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a tank for water and a number of animal rearing compartments
therein comprising: a tapered base for said tank, said
base having a discharge port at its tapered end and a
valve at said discharge port for selectively sealing said
discharge port; and means for double pulsing said valve
so as to open it twice, the first opening and closing to
provide a local turbulent pulse for dislodging waste material
in the tank base and for consolidating it at said discharge
port, said second pulse reopening said valve for a time
sufficient to remove the consolidated waste at said dis-
charge port.
These and other objects of this invention will
be better understood in connection with the following
description taken in conjunction with the drawings wherein:
Brief Description of the Drawings
Figure 1 is a plan and sectional view of an
aquaculture tank for the rearing of crustaceans or other
aquatic animals, showing a tapered bottom member, and a
valve at the discharge port which can be actuated in a
double pulsed manner;
Figure 2A is a diagrammatic illustration of the
waste in the bottom member of the tank of Figure 1 prior
to the first flush pulse;
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Figure 2B is a diagrammatic illustration of the concentration
of the waste after the first flush pulse and just prior to the
second flush pulse; and
¦I Figure 3 illustrates a simple poppet valve which may be uti-
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5 lized as the dump valve illustrated in Figure 1. 5
jl Detailed Description
Referring now to Figure 1, an aquaculture tank 10 may include
a cylindrical member 12 fitted into a tapered base or bottom mem-
lber 14 which, as illustrated, is in the form of a funnel having a
lO l'frusto conical portion 16 and a cylindrical discharge conduit 18. 10
A dump valve 20 is interposed in conduit 18 or, alternatively~
~¦may be placed at the smaller end of the frusto conical cone section
(not shown). The dump valve is, in general, a quick-acting valve
~land more particularly, has a characteristic of quickly closing so
15 !as to generate a turbulent pulse localized in the base which is 15
utilized in breaking up waste material which has settled and con-
gealed over the bottom of the tank.
Dump valve 12 is actuated by conventional actuator 22 which
llis controlled by a conventional control unit 2~ which may include
20 11 a conventional timer or programmer. 20
The tapered bottom member is disposed above a runoff channel
26 such that when the dump valve is opened, water and waste from
the tank are discharged as il]ustrated by arrow 28.
Il In the configuration shown, water is introduced into the tank
25l~via tubing and fitting 30 disposed in tapered bottom member 14. 25
Air is introduced ~lia an aerator 32 in the for~ of a perforated
or porous rod which is also disposed in tapered bottom member 14.
The tank, in a preferred embodiment, is provided with a num-
ber of basket type animal rearing compartments 40 which are stacked
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as shown and attached to a strong back member 42 which also houses
a removable feed rod 44 having cavities 46 which carry food to
compartments 40 by presenting it through an aperture 48 in one of
the walls of a compartment.
5 j It will be appreciated that feed rod 44 may be removed from 5
the strong back member as illustrated by arrow 50 J or the entire
stacked basket arrangement may be removed by pulling up the strong
back member as illustrated by arrow 52.
The tank, in the illustrated embodiment, is provided with a
10l skimmer 56 which fits over the top lip 58 of the tank such that 10
water pumped in from the bottom via line 30 overflows top lip 60
~of the skimmer and into a channel 62 from which the overflow water
llexits at outlet 64.
¦i In operation, water and air bubbles travel upwardly in the
lSj tank and carry with it a certain amount of light waste material 15
¦ which is then skimmed from the top of the tank via skimmer 56. In
~¦this embodiment, the tank is protected from unwanted bacteria from
¦¦the surrounding air by virtue of the fact that the skimmer surrounls
l¦the complete top of the tank such that any bacteria OT other con- I
20~ taminants from the atmosphere are flushed away before they can 20
enter the region of the tank where the animals are being reared.
Waste in the form of uneaten food and excreta from the animals
which is too heavy to be removed in this manner, in general, is
pushed out of each of the compartments by the animals in the com-
partments and falls to the bottom of the tank where it is allowed ~25to collect. Over a period of a couple of hours, this mass of mat-
erial on the bottom of the tank congeals into a layer which is not
easily removed.
I It has been found that by actuating dump valve 20 such that
301 when it closes, it closes rapidly, the resulting loud, turbulent 30
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pulse dislodges and breaks up the conglomerated waste material in
the bottom of the tank. Due to the directing nature of the bottom
,of the tank, this slurry is concentrated above the valve.
, The situation prior to the first flush pulse is illustrated
S lin Figure 2A, and after the first flush pulse in Figure 2B. Note,' 5
~that in Figure 2B, the waste material is compacted into a small
I portion of the bottom member immediately above valve 20 as illus-
trated by reference character 70. Because of this compaction, it
may be removed quickly and with very little loss of water. I
10 1 In one operative embodiment of the subject invention, when thelO
tank capacity is 45 gallons, it is possible to completely clean
the bottom of the tank of Figure 1 without special auxiliary equip~,
ment or procedures and with a water loss of only 2 quarts. This
results in a tank water level drop of only 1 inch as illustrated
by arrow 72. It will be appreciated that a water drop of this l15
amount leaves enough water in the tank to cover all of the animals
within the tank and thus does not subject them to trauma. In an
optimum configuration the first pulse opens dump valve 20 within
l five seconds and then shuts the valve off. This is followed by
another five second pulse, s~hich completely discharges all of the l20
~waste material. I'
¦ ' Referring now to Figure 3, dump valve 20 may be in the form of
a poppet valve 80 which rests on an integrally formed valve seat
shown at 82. The valve in general may have a conical portion 84 I,
251 and a valve stem 86 which may be pushed upwardly as illustrated by'2S
arrow 88 to open the valve. Merely ~uickly removing the upward
force on the valve stem results in the poppet valve snapping back ,
! into place as illustrated, and its rapid movement is, in general,
l caused by the large volume of water located above the valve. The ,
301 poppet valve is extremely inexpensive and effective in producing l30
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the aforementioned turbulent pulse, although any type quick-acting
valve may be utilized.
What has therefore been provided is an extremely efficient
Imethod and apparatus for cleaning the bottom of aquaculture habitats
5 l,while utilizing a minimum amount of water and which has an excep- 1 5
lltionally good cleaning characteristic due to the double flush pulse
!Itype actuation of the dump valve used in connection with a tapered
~bottom member for the tank. It will be appreciated that the more I
severe the taper, the more compact will be the waste material after
10 llthe first flush pulse is delivered to the valve. The more compactllO
~the waste, the less water it takes to remove it and thus, in
¦general, the area above the valve is kept small so that the waste
¦may be removed promptly.
Although preferred embodiments of the invention have been
described in considerable detail for illustrative purposes, many lS
modifications will occur to those skilled in the art. It is there-
fore desired that the protection afforded by Letters Patent be
. 1 mited only by the true scope of tbe appended claims.
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