The present invention relates to equipment for the collection, transport and destruction of organic material from aquaculture facilities, in particular fish eggs, fish fry, srnolt and small fish from hatcheries.

Mortality of fish in aquaculture production facilities can occur any time such as soon after stocking as a result of handling, stress or at any time during culture as a result of disease or water quality deterioration. The amount of mortality is variable among facilities ranging from a few !o large numbers of fish, but high mortality is the exception, Dead fish may sink to the bottom and not be seen, but they also float to the surface and accumulate around the edges of the pond, basin or floating cage where the fish is kept.

There are commonly known different types of equipment or means for manual or auto- mafic removal of dead fish from aquaculture facilities. One known system uses a flexible hose which is provided with an outwardly protruding funnel shaped opening attached to the bottom of the floating aquaculture cage whom the fish is kept. A compressor supplies compressed air through an air nozzle at the funnel by the Inlet end of the hose. The air hubbies generated by the compressed air creates a water current (pumping effect) in the hose leading the water with any dead fish to a fish destruction site where the deed fish Is removed from the wafer, then ground end finally chemically destrucfed. This known system Is running on a continuous basis, 24 hours a day. Another known solution is based on the same principle of using a pipe stretching down to the bottom of the fish cage, with the same type of destruction means and also being provided with a funnel shaped opening to suck in dead fish. But instead of using compressed air to obtain pumping of water through the pipeline or hose, an ordinary fish pump is used on a continuous basis.

A disadvantage with these known, ocean-based systems for extracting dead fish is that they are energy consuming since they are run on a continuous basis and large amounts 5 of wafer Is continuously pumped through the systems. Another major disadvantage is the fact that these systems are mostly fixed to the bottom and thus do not extract dead fish that are floating in the fish cage or pond. Besides, this type of dead fish collecting systems cannot be used In land-based hatcheries such as for salmon and trout winch are most common In Norway. In such hatcheries, the salmon and front are grown from when they H) are hatched appearing as fish fry and until they become s oif and smaller fish in the tanks where the small is kept, the water circulates with a large number of smoit/flsh and if Is difficult to extract the dead from the living fish. The above mentioned automatic systems for removal of dead Ash can therefore not be used.

IS T e present invention is based on the use of liquid ring screw pumps, preferably with a maoerator that can handle liquid containing particles that may he ground to smaller pieces. Pumps of this kind are commonly used in vacuum sewage systems on hoard ships and on offshore Installations. However, such systems are also increasingly being used on land due to reduced water requirement and easy handling and treatment of waste water, as 20 well as Its flexibility as regards installation of piping and layout given by such systems.

With the present Invention Is provided an equipment for collection, transport and destruction of dead fish, In particular from land-based hatcheries for salmon and trout, where the fish Is removed hyglenlcaiiy and effectively. The equipment is cheap to install and Is op- 5 erated with low energy consumption. The equipment is characterized by the features as defined in the attached claim 1 and sub-ordinate claims 2 - 6

The Invention will be described in more detail in the following with reference to the attached figure. Referring to the figure, the system or esiuipment according to the invention includes a vacuum tank 1 designed to hold a quantity of dead fish eggs, fish fry, smelt and small fish, hereinafter organic material, and wafer. Vacuum in the tank 1 is, as stated above, preferably obtained by means of one or more liquid ring screw pumps 2 provided on a vacuum generating unit 3 A vacuum pipe 4 Is connected with the tank through a strainer § provided within the tank 1 and stretches to the suction aide of the pump 2. Water from the pump 2 is transported via an outlet pipelS to a suitable drainage 18 in the floor. The strainer may be in the form of an upright, cylindrical element or perforated pipe element as is Indicated in the figure. Further, the strainer is easily releasable for cleaning (net further shown). The tank 1 Is further at the bottom end, via a pipe stub 6 provided with a motorized valve ? connected to a silage tank 8, preferably arranged directly below the vacuum tank 1 , for further processing and destruction of the collected organic material. Within the tank 1 is also provided a level control 14 to defect the organic mate lal/water level in the tank, the function of which will be further described below. A suction pipe 9 connected to the top of the tank 1 stretches to a suitable place, or via branches of such pipe to different pieces within the hatchery where the organic material can be deposited or collected. The organic material may be removed from the hatchery tanks (net shown) In at least two ways; 1} either by using a suction head provided on a flexible hose (not shown In the figure) connected to the suction pipe 9 that can be manuall operated by a person, sucking the dead fish directly from the smelt tank or; 2) by using a collection tray or receptacle 10 as shown in the figure. Referring to the latter alternative 2), a discharge valve 11 1s provided on the suction line 9 prior to the receptacle 10 which can be controlled by a release button (switch) 13. The receptacle is connected to a water supply source 12 which is required for the fish transport.

The working principle of the invention as shown In the figure, alternative 2) is as follows; The vacuum pump 2 Is Initially started to bulk! up required vacuum In the in the tank 1 The organic material Is collected from the aquaculture tank by an operator using a net or other suitable fool for catching dead fish. The organic material is then placed In the col· lection receptacle 10 and water is added In the receptacle from the water lap 12, When the organic material and water reach a desired level in the receptacle 10, the operator triggers the release button 13 to o en the discharge valve 11, The organic material and wafer are then socked Into the suction pipe 9 and are transported towards the vacuum tank 5 Gradually; by conveying successive charges of organic material and water, the vacuum tank 1 will be filled with such material, while the water togethe with air Is sucked out of the lank 1 through the strainer 5 by the vacuum pump 2 It should be stressed that the organic material ma be discharged from the receptacle 10 without the addition of water. However, addition of water is recommended to Improve transport In the pipe 9 as well as for cleaning of the pipe and obtaining proper working of the vacuum pump(s) 2. Whan the organic material reaches a desired level, the level centre! 14 triggers an emp- lying operation of the vacuum tank 1 Initially the vacuum pump 2 is stopped and then, by opening the valve 7 between the vacuum tank and ensilage tank 8, air is air admitted to the vacuum tank 1 via the ensilage tank 8 and the pressure in the vacuum tank reaches atmospheric pressure. The organic materia! will now fall Into the ensilage tank 8, Through the connecting pipe 6, Afte emptying of the vacuum tank 1 , the valve 7 is closed and the vacuum pump is started resuming the vacuum In the tank 1 Thus, the equipment according to the Invention represents a semi continuous solution where the vacuum pump normally maintains a vacuum level In the tank 1 , until the pump is intermittently stepped when It is necessary to empty the tank. The equipment Is automatically operated by means of a programmable logic control, PIC, which will not be further described,

As an alternative, as mentioned above under Item 1), the organic material may be sucked directly from the hatchery tanks by a suction head provided on a flexible hose (not shown) connected to the suction line 9 Such hose is manually operated and is provided with a suitable valve (not shown) to initiate suction by the operator. Since the liquid screw ring pump 2 requires both air and water to be effectively operated, an air nozzle Is provided In conjunction with the operator vale to admit some air to the suction line 9.