Harvesting apparatus

A harvesting apparatus includes an inlet capable of engaging a body of water, a first separating stage and a control device. The control device is operable to control the flow rate of water over the inlet to the first separating stage. The control device operates by adjusting either the first separating stage or the inlet to control the flow of water to the first separating stage.

The present invention relates generally to a harvesting apparatus, and 
relates particularly to a harvester and separator for use in a water 
environment. Particularly, the harvesting apparatus of this invention is 
suitably used in conjunction with a water vessel. More particularly the 
harvesting apparatus is capable of collecting surface or near-surface 
water, and of separating therefrom matter contained therein. 
The matter to be separated may be any type of matter such as plankton, 
whether it be zooplankton or phytoplankton, dispersed oil from oil spills 
or the like, or even flotsam such as discarded rubbish or other solid 
pollutants. Further description of the invention will generally relate to 
the harvesting of zooplankton from a mass of water such as the waters of 
seas, rivers, ponds, and lakes or the like. 
Plankton are small animal and plant organisms having weak locomotive power, 
which float or drift in the water and which form an integral part in the 
aquatic food chain. Various aquacultural installations particularly those 
involved with the culture of marine species such as prawn farms, demand a 
reliable supply of live zooplankton. This in turn may demand the 
harvesting, separation, and concentration of plankton. To date, fixed 
harvesting and separating systems have been proposed but those have 
inherent disadvantages and limitations. 
Zooplankton naturally employ spacial and temporal variability as a defense 
against predators. They do not remain in one location, and may appear in 
or disappear from an area in the water mass at random thus ensuring 
survival. As such, known harvesting and separating systems cannot provide 
efficient harvesting as they either lack flexibility or volume. 
Specifically, a system having a large pumping facility is very difficult 
to relocate when required, while systems having the ability to be portable 
generally have pumping systems which are of low volume. 
Further, known harvesting devices extract water with entrained plankton 
from a pond or the like, and either recirculate the water back to the 
pond, or dump the water elsewhere. The latter method has obvious problems 
of having to continually re-fill the pond, and the former method requires 
extra piping and usually creates unwanted currents away from the inlet 
which disperse the accumulated plankton. Both options also cause the 
serious problem of dilution of the water, with respect to both the volume 
and location of the plankton. 
An object of the present invention is to obviate, or at least partially 
alleviate, the above disadvantages of known harvesting and separating 
systems. 
The present invention provides a harvesting apparatus including an inlet 
means capable of selectively engaging a body of water at or near the 
surface thereof; 
at least a first separating stage; 
said apparatus being operable to allow water to flow over the inlet means 
to the at least one first separating stage by relative movement between 
the inlet means and the body of water; 
a pivotal communication between said inlet means and said first separating 
stage capable of independent vertical movement; and 
control means able to be co-ordinated with the pivotal communication; and 
operable to control the flow rate of water over said inlet means to said 
first separating stage, and able to be co-ordinated so as to adjust the 
height, depth or angle of the first separating stage relative to the 
surface of the body of water. 
It is preferred that the inlet means and first separating stage are in 
pivotal communication with each other, and are capable of relative 
movement to each other. It is most preferred that the control means is 
operable to control this movement. The pivotal communication may be 
provided by a direct pivotal axis between the inlet means and first 
separating stage, however, it is most preferred this pivotal communication 
is provided by an interim platform placed between the inlet means and 
first separating stage with each of said inlet means and first separating 
stage capable of separate pivotal movement from the interim platform. The 
control means may be operable to raise or lower the interim platform. 
The inlet means may be of a variety of forms, but most preferably of a form 
capable of creating at least a wash over the first separating stage. For 
example, when incorporated into a water vessel the inlet means may be a 
free flowing inlet means having an opening directed forwardly of the 
vessel, which receives water due to the relative movement between the 
vessel and the body of water. Alternatively, the inlet means may be a 
pump-fed inlet means or the like. Another alternative is to provide a bar, 
such as a rounded bar that simply creates a wash when placed in or on the 
surface of the body of water. The creation of a wash should be sufficient 
to provide a flow of water over the first separating stage. Preferably, 
the inlet means is of the scoop type, and is a relatively wide scoop 
having a forwardly directed leading edge, and being capable of pivotal 
movement from an inoperative position, such as one out of the water, to an 
operative position in fluid communication with the water. 
According to a preferred aspect of the invention, the, or a first 
separating stage comprises a primary screen classifier having a 
substantially flat surface, an upstream end pivotably connected to the 
inlet means, and a downstream end having an associated collection trough. 
The primary screen classifier should be capable of separating water from 
substantially all matter of a size greater than a predetermined minimum 
size, and to retain the matter on the primary screen classifier. 
Water from the inlet means may pass over the primary screen classifier. The 
primary screen classifier may include a mesh having a predetermined 
aperture size that will allow water and undersized matter to pass through. 
The screen may alternatively be a filter screen to assist the separation 
of oil from water. The matter that is larger than the predetermined size 
will remain on the primary screen classifier. This matter may then be 
collected and stored, or alternatively may undergo further separation and 
classification. 
In a further preferred form, the primary screen classifier of the, or a 
first separating stage includes a primary collection trough located at the 
downstream end of the primary screen classifier, away from the upstream 
end where the water enters the primary screen classifier. By increasing 
the flow rate over the primary screen classifier, the matter separated 
from the water which remains on the primary screen classifier may be 
flushed therefrom into the collection trough. 
Preferably the flush water is an increased volume of water from the inlet 
means which is caused to wash over the primary screen classifier at a rate 
too fast to allow passage of the water through the screen, but fast enough 
to wash off the primary screen classifier substantially all of the matter 
collected thereon. The flush water serves to wash the matter so separated 
into the collection trough, where that matter together with the flush 
water may be transferred by pump or other means to further separating 
stages or to storage means such as holding tanks or the like. The 
apparatus may be connected to a water vessel having hulls, and 
conveniently, the holding tanks may be located in these hulls. The volume 
and frequency of the flush water is dependent upon both the concentration 
of matter in the water and the rate at which separation is being effected. 
The inlet means and primary screen classifier should be capable of pivotal 
movement between an operative position, where, in use a steady flow of 
water is maintained over the primary screen classifier, and a flush 
position where the pivotal movement of either or both of the inlet means 
and primary screen classifier will cause an increase in water flow over 
the primary screen classifier. 
The control means is operable to control the rate of water across the first 
separating stage, and hence the primary screen classifier. Generally, the 
control means may take the form of acting upon either or both of the inlet 
means and first separating stage, to pivot either and hence alter the flow 
rate. In a preferred form, the control means may work on and lower the 
downstream end of the first separating stage. In this way, the primary 
screen classifier may be pivoted to increase the slope thereof to cause a 
rush of water of increased flow rate, which subsequently washes the 
primary screen classifier and flushes matter into the collection trough. 
The primary screen classifier may be returned to its original position to 
resume normal operation in an operative position. Of course, the original 
position may be horizontal or may be at an angle, again depending on 
operating conditions. 
In a further preferred form, the inlet means may be combined with the first 
separating stage to allow for coordinated action between these two 
components. The inlet means is arranged upstream of the first separating 
stage, and in one form both are pivotally attached to an interim platform 
or the like, about which each is capable of separate pivotal movement. The 
interim platform should be able to be raised or lowered, which may provide 
control of the angle of the inlet means and first separating stage 
relative to each other. Of course the interim platform may be omitted and 
the scoop may be pivotally attached directly to the upstream end of the 
primary screen classifier, or to an interim construction of the first 
separating stage so that each is capable of separate pivotal movement 
about a common axis. The common axis itself is capable of being raised or 
lowered. 
The flowrate of water over the inlet means and thus over the primary screen 
classifier, and also the flowrate of the flush water, may then be 
controlled by the control means by pivoting the scoop to adjust the angle 
thereof (and thus the depth below the surface of the water), and also by 
pivoting the primary screen classifier to adjust its angle. Further 
control may be provided by raising or lowering the interim platform in a 
substantially vertical plane. Alternatively, and where the interim 
platform is omitted, the pivotal axis between the first separating stage 
and inlet means is capable of being raised or lowered. In use control of 
this pivotal connection between the first separating stage and inlet 
means, allows for control of the angle of each component and hence of the 
flow rate over the primary screen classifier. 
It is preferred in an operable position that the first separating stage is 
maintained substantially flat, on or just above the surface of the water 
as the action of the water acting on the screen of the primary screen 
classifier helps to keep it free of matter clogging the screen. 
The pivotal communication connecting the first separating stage and inlet 
means may be raised or lowered in response to changes in weight, or 
operating depth of the apparatus due to filling or emptying of the 
collection troughs. In use, as the collection troughs are either filled or 
emptied, the depth of the first separating stage may alter relative to the 
surface of the body of water, or indeed the relative angle of the first 
separating stage may be effected. By raising or lowering the pivotal 
communication between the first separating stage and inlet means, 
separately, or in conjunction with changes to the height at the downstream 
end of the first separating stage, this change in depth or angle may be 
compensated for and maintain the first separating stage substantially flat 
and at a level on or just above the surface of the body of water. 
Similarly, the downstream end of the inlet means may be adjusted in 
response to those same changes in weight and consequently depth, to 
maintain it at approximately the same level on, or just below the surface 
of the body of water. It will generally be a co-ordinated action between 
various control means to maintain the downstream end of the inlet means 
and the first separating stage relatively flat and at a level near the 
surface of the body of water. 
The control means that controls the pivotal movement of the scoop and the 
primary screen classifier, and also the vertical movement of the pivotal 
communication thereof, may comprise any known operable means. Preferably, 
the control means comprises separate hydraulic rams, secured to lines 
attached to the free ends of the scoop and the primary screen classifier 
respectively or at the pivotal communication, to raise and lower those 
free ends and cause the pivotal movement. A manual mechanism, such as a 
hand operated worm drive, may be used to provide the vertical movement. 
However, it will be understood that any mechanism, automatic or manual, 
hydraulic or electric, may be utilized to provide the required movement. 
The apparatus may be attached to a water vessel, preferably in the form of 
a catamaran, and may be of a size enabling it to be readily transportable 
over land such as by being towed on a suitable trailer behind a vehicle. 
In this form, the inlet means and first separating stage of the harvesting 
apparatus of the present invention may both be located between the twin 
hulls of the catamaran. Indeed, in a most preferred form, the apparatus is 
provided between the hulls, and is secured a short distance above the 
surface of the water, to allow the movement described above. The operating 
water may then be removed from the body of water, and immediately returned 
to the body of water after passing through the primary screen classifier, 
requiring little energy due to the small displacement of the water above 
the surface and the short path of travel through the system. 
It should also be understood that a third degree of control of the flowrate 
through the system is provided by the propulsion of the vessel through the 
water, which allows either an increase or decrease in flowrate depending 
on water conditions such as currents and the like. In a preferred form, 
the vessel derives its propulsion when in the water from an out-board 
motor or the like, located and secured in a normal manner. 
Preferably, when used as a zooplankton harvestor the matter collected in 
the primary collection trough is passed to a secondary separator to 
achieve further separation and classification. Accordingly, the present 
invention may include a second separating stage comprising; 
at least a first separator screen; 
and transfer means operable to transfer said slurry collected from the 
primary screen classifier to the first separator screen. 
The secondary separator preferably comprises three tiered separating 
screens, arranged so that successive classification occurs from the first 
to the second to the third, and so that classified matter may be collected 
from each one separately and subsequently be passed to storage or holding 
bays. 
The matter from the primary collection trough is preferably pumped 
therefrom to a an outlet located over the first of the tiered separating 
screens of the secondary separator. The outlet ejects the matter in slurry 
form over the first screen. Preferably, the screen is a mesh having an 
aperature, which is sized to collect matter of a predetermined size and to 
allow matter of a smaller size together with substantially all of the 
water of the slurry to pass therethrough. The smaller size matter and the 
slurry water may pass to a second screen where matter of a successively 
smaller size is collected. This operation continues to the third screen 
after which the slurry water and any remaining unwanted matter is allowed 
to return to the body of water. 
Preferably, each of the screens are inclined and at the lower end of each 
screen collection troughs are provided which receive the classified 
matter. In order to wash the classified matter from the screens into those 
troughs clean-water spray nozzles may be provided thereabove. The 
clean-water spray nozzles may be fed from the water which has passed 
through the primary screen classifier, a separate reservoir associated 
with the first separating stage or may be drawn from the body of water 
through a pipe with a filter, preferably a 63 micron filter cartridge. 
This water may be pumped by a separate pump from that which pumps the 
slurry to the outlet. A suitable location for the inlet for the pump is 
immediately below and at one end of the first separating stage. 
The primary screen classifier may include a belly-plate associated with the 
primary screen classifier having a number of apertures therethrough, one 
of which may be connected directly to a sump or the like for collection of 
water for the clean-water spray nozzles. 
In a further preferred form, the apertures of the belly-plate may be 
provided with venturi baffles projecting below the surface thereof. The 
primary screen classifier may then be operated at a level where the 
belly-plate contacts the surface of the mass of water causing a venturi 
effect through the primary screen to increase separation efficiency. 
All of the controls for the pumps and operating members of the vessel are 
preferably housed in a central control point so that a person may pilot 
the vessel and also control the harvesting and separating operation. 
Alternatively, some or all of the operations of the vessel may be done by 
remote control, such as by an operator located on shore.

Illustrated in FIG. 1 is a harvesting vessel (indicated generally as 10) 
according to the present invention having an inlet means 12, a first 
separating stage 14, a second separating stage 16, and a central control 
area 18. 
Inlet means 12 is a scoop 12a having a bottom wall 20, side walls 22, a 
leading edge 24, and a trailing edge 26 (better illustrated in FIG. 2). 
Baffles 28 are provided to assist flow of water thereover (baffles 28 are 
shown in FIG. 1 in outline only). FIG. 1 also shows the inlet means 12 in 
both a raised X position, and a lowered Y position. 
The trailing edge 26 is pivotally attached to guide means 30, which also 
allows vertical movement of trailing edge 26 along runners 32. The 
vertical movement may be controlled manually by a hand operated winding 
mechanism such as a worm-drive or the like (not shown). The leading edge 
24 of the inlet means 12 is secured by a line 34 via pulley 36 to a 
hydraulic ram 38. Ram 38 is controlled within control area 18 to either 
lower or raise the scoop 12a. 
The first separating stage 14 is illustrated in FIGS. 3, 4, and 5 and 
includes primary collection trough 52, and a primary screen classifier 40. 
The primary screen classifier is supported on side and end frame members 
42, and stringers 44. 
The primary collection trough 52 is located immediately adjacent the 
downstream end of the primary screen classifier 40. Piping 54 communicates 
with exit hole 58 so that a slurry may be pumped from collection trough 52 
via pump 56 to the secondary separating stage 16. 
The first separating stage 14 is also pivotally attached to guide means 30, 
and to the inlet means 12 at axis 58. Thus, the primary screen classifier 
40 may be pivotally raised and lowered about axis 58, by a line 60 secured 
at flange 62, and passing to hydraulic ram 64 via pulley 66. The position 
of the upstream end of the primary screen classifier 40 is also able to be 
vertically raised and lowered in conjunction with the trailing edge 26 of 
the scoop 12. It should be noted that the first separating stage 14 is 
preferably in one rigidly secured piece, and thus pivots as a whole. In 
order to allow this pivotal movement piping 68 from the primary collection 
trough 52 to pump 56 is flexibile. 
The apparatus of the invention may be located between twin hulls 70 of a 
vessel 10 (best shown in FIG. 2). In operation, the vessel 10 of the 
present invention is piloted across waters by normal steering controls 
such as a rudder or the like (not shown) and is propelled by an out-board 
motor or the like (also not shown) secured to the vessel at point 72. The 
vessel 10 may be directed to an area of water in a pond or lake or the 
like where plankton, such as zooplankton, are at or near the surface 
thereof. Once at that area of water, the scoop 12a may be lowered into the 
water to a depth at which the zooplankton are located, and which provides 
a required flowrate of water thereover and to the first separating stage 
14. The water has plankton encapsulated therein, and the required flowrate 
of water over the scoop 12a will be dependent on the concentration and 
depth of that plankton. However, the operator will generally be visually 
guided by observing the amount of plankton collecting on the primary 
screen classifier 40, and the speed with which the water is passing 
therethough. 
The water and encapsulated plankton pass over scoop 12, across the gap 
between scoop 12 and the primary screen classifier 40 (which gap is 
covered by a layer of mylar fairing 74 or the like--as shown in FIG. 5), 
and onto the primary screen classifier 40. Preferably, the primary screen 
classifier 40 is a stainless steel woven mesh having apertures therein 
comensurate with the size of matter to be separated. Thus, substantially 
all of the water passes through the mesh together with matter less than 
the size of the aperture. Matter larger than the size of the aperture is 
retained by the mesh. 
Periodically, the primary screen classifier 40 is flushed by water from the 
scoop 12 in order to wash accumulated plankton into primary collection 
trough 52. Pump 56 may operate periodically or continuously while scoop 
12a is lowered, and is capable of pumping collection trough 52 dry without 
incurring any damage. Therefore, once the primary screen classifier 40 is 
flushed and a slurry of plankton and water enter the collection trough 52, 
pump 56 passes that slurry through piping 54 and 58 to the second 
separating stage 16. 
The primary screen classifier 40 is flushed by activating ram 64 to lower 
the downstream end of, and thus pivot, the entire first separating stage 
14 to increase the slope thereof. The flowrate may by increased further at 
the same time by activating ram 38 to increase the depth of the leading 
edge 24 of scoop 12. In any event, the flowrate over primary screen 
classifier 40 is caused to increase such that substantially all of the 
accumulated plankton washes into primary collection trough 52. Further 
control of the flowrate may be provided by altering the vertical height of 
guide means 30. 
Illustrated in FIGS. 6 to 9 are various views of the second separating 
stage 16. The second separating stage 16 includes three tiered separating 
screens, namely first screen 80, second screen 82, and third screen 84, 
all supported in a framework generally indicated by the numeral 86. As 
illustrated by the top-view of FIG. 7, the three screens are each 
relatively wide, approximately to the half the width of the primary screen 
classifier 40, although they may be wider. 
The slurry from primary collection trough 52 is passed via piping 58 and 
pump 56 to an outlet 88 which extends across the width of first screen 80. 
Outlet 88 discharges the slurry onto screen 80, and depending on the size 
of screen selected (which in turn generally depends on the particular use 
of the vessel, and the size of plankton required), plankton larger than 
the screen aperture are retained, while smaller plankton passes through 
the screen to the second screen 82 via fixed tray direction plate 90. A 
similar operation occurs from second screen 82 to plate 92, and from third 
screen 84. However, anything passing through third screen 84 returns 
directly to the body of water between hulls 70 and downstream of the first 
separating stage 14. 
Once trapped on an appropriate screen, the different sized plankton is 
rinsed into respective collection troughs 94, 96, and 98 by respective 
clean-water spray nozzles 100, 102, and 104. The water for the clean-water 
spray nozzles may be provided by a separate smaller pump. The water is 
drawn from that water leaving the first separating stage 14, or from a 
reservoir which is connected to an intake pipe 118 or directly from water 
body through a filter cartridge. The clean water is preferred to prevent 
blockage of the relatively fine apertures of the nozzles 100, 102, and 
104. 
From collection sumps 94, 96, and 98 the plankton drains via outlets 106, 
108, and 110 to graded holding tanks which may be located in either or 
both of the hulls 70 of the vessel. From those holding tanks, the graded 
plankton may be passed directly to fish ponds or into vehicle mounted 
tanks for transportation. 
Thus it will be appreciated that the harvesting vessel 10 of the present 
invention has the advantage of being able to locate and follow plankton 
within one large water body or between different bodies of water so that 
continuous harvesting and separating can be effected. This can be achieved 
without dispersing the remaining plankton, and without being limited to 
plankton in only one location, providing adaptability for various types 
and locations of plankton. 
A further advantage lies in the preferred relationship between the inlet 
means and the first separating stage. The ability to raise or lower the 
leading edge of the scoop, to adjust the height of the hinge point between 
the scoop and the primary screen classifier, and to adjust the slope of 
the primary screen, all improve the efficiency of the vessel. The various 
combinations of angles which may be achieved have an effect on the depth 
from which plankton can be harvested, the volume of water passing over the 
scoop, the rate and efficiency of filtration over the primary screen 
classifier, and the rate and concentration of plankton into the primary 
collection trough. Various of these considerations are important for 
various harvesting conditions. 
The present invention gives flexible, high volume harvesting, by a portable 
and easily deployable machine. The machine has the ability to operate 
between widely dispersed areas either within a single large water mass or 
between different water masses. Further, large pumps and complex machinery 
are not required to filter large volumes of water. 
It will be appreciated that various modifications and alterations may be 
made to the above described harvesting vessel without departing from the 
ambit of the present invention.