APPARATUS FOR SEPARATING EXCREMENT AND FEED REMAINS IN A PISCICULTURE CISTERN

Abstract: Apparatus for separating excrement and feed remains from water continuously supplied and recirculated to a pisciculture cistern (1) includes a container (12) in which a first pipe (11), through which contaminated water is discharged into the container, projects such that the opening of said pipe is below the water surface in the cistern and suitably at a distance from the central axis of the cistern. A second vertical pipe (13) with a greater cross section than the first pipe and with an upper end which is closed or opens out above the water surface in the cistern, and which has a lower end opening out between the bottom of the container and said opening on the first pipe, is fixed inside the container in an eccentric position relative thereto. A third vertical pipe (14) thrusts up into the container and has an upper opening constituting an overflow for the water in said container. The openings of the first and third pipes (11 and 14) are separated from each other by a vertical wall on the second pipe (13) so that after separation from the contaminants subsequently deposited on the bottom of the container the water flowing out of the opening of the first pipe (11) is forced to pass under said wall and thereafter upwards before it is passed into the third pipe (14).

Description: Title Apparatus for separating excrement and feed remains in a pisciculture cistern. Technical field The present invention relates to an apparatus for separat¬ ing excrement and eed remains in a pisciculture cistern, which is preferably continuously supplied with water. Background art When breeding fish in large cisterns it is a desire that excrement and feed remains are removed so that the quality of the water will not deteriorate. If excrement and feed remains are allowed to remain in the cistern for some time, they are leached and dissolved, resulting in that the water is given a higher ammonia and nutrient salt content. Ammonia is poisonous at higher pH values, and the nutrient salts stimulate the growth of algae. Different methods have been proposed for rapidly remov- ing the excrement and waste feed. One such method consists in oxygenated, purified and recirculated water or fresh water being preferably continuously supplied to the cistern and the same amount of contaminated or exhausted water tapped off at the lower portion of the cistern, excrement and waste feed lying on the bottom of the cistern thus also accompanying the discharged water. The contaminated or exhausted water can be guided in given paths in the cistern,, e.g. through strainers or concentric tubes, to prevent the fish in the cistern accompanying the discharged flow of water. The primary disadvantage with this method is that a very large amount of water is discharged together with the excrement and waste feed. To cater for this contaminated water and to clean it, it must be taken to special settling tanks, which will be very large if the volume of the cistern is large and/or the number of cisterns is large. The discharge of a large amount of water has other disadvantages too, such as heat losses and the exaggerated dimensioning of oxygenating and filtering apparatus. Disclosure of the invention The object of the present invention is to provide an apparatus for separating excrement and waste feed in a pisciculture cistern, by means of which the above-mentioned disadvantages of previously known apparatus are circumvented. This object is achieved by the invention being given the distinguishing features disclosed in the patent claims. The advantages with the invention is that the excrement and waste feed are rapidly removed from contact with the water in the cistern, whereby poisoning the fish and increased growth of algae is avoided, that a comparatively small amount of pirified, recirculated and/or fresh water needs to be added to provide the rapid removal of excrement and waste feed, and that the excrement and waste feed are separated from the water in the cistern already, whereby the discharged water is given a high degree of purity, and can even be used for refluxing to the cistern without subsequent filtration and the excrement and waste feed are catered for at a place not in immediate contact with the water in the cistern, where these can sediment and be discharged when suitable, e.g. directly to the sewage network without any great amount of water being discharged thereby. Further advantages are that the apparatus lacks moving parts, has a simple construction and is easy to erect, dismantle and look after. Brief description of the drawings Figure 1 is a cross-sectional view of a part of a pisciculture cistern including a device in accordance with a first embodiment of the invention. Figure 2 is a cross-sectional view of a part of a pisciculture cistern and apparatus situated outside it, in accordance with a second embodiment of the invention, and Figure 3 is a cross-sectional view of a part of a pisciculture cistern and apparatus situated outside it in accordance with a third embodiment of the invention. Preferred embodiments The pisciculture cistern 1 illustrated in Figure 1 is provided with a bottom 1a, sloping in a direction towards its OMPI vertical central axis. Via a conduit 2 there is preferably continuously supplied to the cistern 1 water which is fresh, or purified by filtering and possibly oxygenated, which recirculates in a plant consisting of one or more cisterns. The conduit 2 is directed, and the flow rate of the water fed in are selected such that the water is given a slight circulatory movement in the cistern round its vertical central axis, whereby excrement and waste feed (contaminants) which have fallen to the bottom 1a glide towards the centre of the cistern, due to the slope of the bottom. In the centre of the bottom 1a, there is a hole in which there is sealingly attached a vertical pipe 3 * The pipe 3 is open upwards and the opening is covered by a strainer 4 * The opening functions as an overflow, signifying that the level of the water in the cistern is somewhat higher than this opening. A tube 5 forming a container surrounds the pipe 3» which is of considerably less diameter than the tube, so that an annular space with relatively large cross-sectional area is formed between tube and pipe. The tube 5 extends upwards past the water surface in the cistern and is possibly closed off at its upper end. The tube 5 is provided with a bottom having a central portion 5a resting on the bottom 1a of the cistern 1 , there being a hole 5b in the centre of the central portion 5a, in which there is attached & sleeve 5d, sealingly surrounding the tube 3. The 'bottom of the tube 5 also comprises an annular outer portion 5c, connecting the cylindrical surface of the tube 5 to the central portion 5a and which is situated at a distance from the bottom 1a so that a gap is formed between the bottom 1a -and the portion 5c. In the outer portion 5c there is a hole, at the edges of which a vertical pipe or conduit 6 is welded such that it thrusts up into the space between the pipe 3 and the tube 5. The gap between the bottom la and the portion 5c and the diameter of the conduit β are so small that fish in the cistern 1 are prevented from coming into the space between the conduit 3 and the tube 5, but the gap is sufficiently large for the contaminants to pass out through the gap and conduit 6. A third pipe 7 is attached to the inner cylindrical surface of the outer tube 5, so that the pipe 7 is situated excentrically in relation to the pipe 3 and tube 5. The lower open end of the pipe 7 is situated somewhat below the upper end of the conduit 6, and its upper open end is situated at the same height as the upper end of the tube 5. The lower portion of the tube 5 functions as a collection container for the contami ants. Since the tube 5> the pipe 7 and the conduit 6 form one unit, which is not attached to the cistern 1, this unit can easily be removed from the cistern when a large amount of contaminants has collected, by lifting it vertically upwards, the inner surface of the sleeve 5d gliding along the outer cylindrical surface of the pipe 3. The contam nants remain in the removed unit together with a small amount of water. The contents can be emptied directly into a sewer, whereafter the unit can once again be fitted into the cistern. By water being continuously supplied to the cistern 1, and the upper opening of the pipe 3 functioning as an overflow, the contaminants gliding down towards the centre of the cistern on the bottom .1a will be sucked via the gap between the bottom 1a and the portion 5e, into the conduit 6 together with a quantity of water corresponding to the quantity supplied. As a result of the minor cross section of the gap and the conduit 6 in relation to the distance between the pipe 3 and tube 5, the speed of the water and the contaminants in the conduit 6 will be relatively greater than their speed after exiting from the conduit. After exiting from the conduit 6, the water and contaminants slowly rise in the space between the tube 5 and pipe 7, but because of the relatively large distance between the tube and the pipe, the contaminants that are heavier than water will fall downwards into the space between the tube 5 and the pipe 7 after a comparatively short movement upwards, while the contaminants that are lighter than water will collect at the water surface in the space between the tube 5 and the pipe 7. A part of the lighter contaminants will become heavier after some time and fall down towards the bottom of the tube 5. The O PI contaminants which remain on the water surface are removed in conjunction with removing the unit, consisting of the tube 5 and the pipe 7 and conduit 6, from the cistern 1 and emptying the unit of its contents. Since the water is given a quiet flow after exciting from the conduit 6, especially when it slowly sinks in the lower part of the space between the tube 5 and the pipe 7, and slowly rises in the space between the conduit 3 and tube 5, the contaminants settled on the bottom of the tube 5 are not whirled upwards, and the water will thus be relatively clean when it reaches the upper part of the space between the tube 5 and the pipe 7. When the water has arrived at the upper edge of the pipe 3 it is thus substantially free from contaminants. The contaminants which possibly accompany the water to said edge are prevented from coming into the pipe 3 by the strainer 4« The optimum relationship of the distance between the members 3, 5, 6 and 7 cannot be expressed exactly, since a plurality of more or less unknown factors have influence. Of these can be mentioned the quantity of water supplied through the conduit 2, the size and shape of the cistern 1, the size and weight of the contaminants, and the length and cross section of members 3, 5 and 7. The relationship will have to be large enough for the rising rate of the water flow to be less than the falling rate of the contaminants. The contaminants are thus collected in the container defined by the lower portion of the tube 5, where they settle. The water which is comparatively free from contaminants flows downwards through the pipe 3 and is suitably fed through a filter for further cleaning, whereafter, after possible heating and/or oxygenating it is once again supplied to the cistern 1 via the conduit 2. A second embodiment of the apparatus in accordance with the invention is illustrated in Figure 2, in this embodiment a portion of the apparatus is situated immediately outside the cistern 1. A vertical pipe or tube 10 is adapted in the centre of the cistern 1, with its bottom portion situated a short distance from the bottom 1a of the cistern 1, said distance substantially corresponding to the distance between the bottom 1a and the portion 5c in Figure 1. The upper end of the tube 10 is situated higher than the water level in the cistern 1 • One end portion of a pipe or conduit 11, inserted in the tube 10, has an upper, open portion functioning as an overflow. The other end portion of the conduit 11 is inserted through the bottom of a container 12, having a circular cross section, such that the conduit projects upwards in said container at a distance from the central axis thereof and approximately to half the height of the container. A vertical pipe or tube 13 surrounds a part of the conduit 11 inserted in the container 12, and is attached to the conta er eccentrically relative thereto. The tube 13 has a lower portion situated under the outlet of the conduit 11 in the container, and an upper end situated above the water level in the container. An overflow pipe or conduit 14 thrusts up through the bottom of the container 12, extends vertically upwards at the side of the tube 13 and has an upper open end functioning as an overflow in the container. In the apparatus illustrated in Figure 2, water together with contaminants is sucked in through the gap between the lower end of the tube 10 and the bottom 1a of the cistern 1, further upwards into the space between the tube 10 and the conduit 11, and thereafter through the conduit 11 to the container 12, where heavier contaminants precipitate and are collected at the bottom of the container, while lighter contaminants remain at the water surface in the tube 13 * Since the water will be given a quiet flow course through the members due to the plaeing and dimensioning of the tube 13» container 12 and conduits 11 and 14, relatively clean water will be discharged through the conduit 14 for further passage back to the cistern 1 , in a similar way as has been described above in conjunction with Figure 1. The contaminants settled on the bottom of the container 12 can be discharged at selected occasions by a valve 15 at the eonieally ιaped bottom of the container being opened. The pisculture cistern 1 illustrated in Figure 3 corresponds to the one illustrated in Figure 2. Fresh water is taken, preferably continuously, into the cistern 1 via a OMPI conduit 22. Water refluxed in the plant, and obtained in a mode described below, is passed preferably continuously into the cistern 1 via a conduit 23. The quantity of fresh water can be kept as low as about 7 of the recirculating quantity of water, depending on the ef ectiveness of the apparatus in accordance with the invention. The conduits 22 and 23 are directed, and the flow speed of the water fed in is selected such that the water is given a weak circulatory movement in the vessel round its vertical central axis, whereby the contaminants that have fallen down to the bottom 1a glide towards the centre of the cistern due to the slope of the bottom. In the centre of the cistern 1 there is arranged a vertical tube 10 and a conduit 11 similar to what has been ' described above in conjunction with Figure 2. The end portion of the conduit 11 projecting from the cistern is taken through the bottom 12a of a separation container 12 situated outside the cistern. This container 12 corresponds to the one illustrated in Figure 2 and contains the vertical tube 13 an a water discharge pipe or conduit 24 thrusting through the bottom 12a of the container 12, extending vertically upwards to one side of the tube 13 and having an upper open end at the same level as the upper end of the conduit 11 in the container 12. The eonduit 24 is connected to the conduit 23 via a filter 25, a circulation pump (not shown) and possibly also osygenating and U.V. light irradiation apparatus (not shown). The container 12 is provided with a conical bottom 12a, the apex of which is downwardly directed and provided with a hole 26. A conduit stump 27 is connected to the portion of the bottom 12a surrounding the hole 26 and depends downwards there- from. A conduit 28, the cross section of which is rather larger than the cross section of the conduit stump 27 is displaceably adapted along the vertical central axis in the container 12. In the position illustrated in Figure 3> the conduit 28 assumes its lower position in which its lower opening rests and seals against the bottom 12a immediately above the hole 26, and its upper opening is at the desired water level in the container for forming an overflow. The conduit 28 is retained in the position O PI _ sealing against the container bottom 12a illustrated in Figure 3 with the aid of means (not shown) on the container 12 or on the tube 13> and can be lifted vertically upwards a short distance from this position so that a gap is formed between the lower portion of the conduit 28 and the bottom 12a. When the conduit 28 is lifted, its. upper portion ceases to function as an overflow and the contaminants collected at the bottom 12a are discharged through said gap and down through the conduit stump 27 together with a small amount of water. In the apparatus illustrated in Figure 3> water and contaminants are sucked in through the gap between the lower portion of the tube 10 and the bottom 1a of the cistern 1, further upwards into the space between the tube 10 and conduit 11, thereafter through the conduit 11 to the container 12, where heavier contaminants precipitate and are collected at the bottom 12a of the container, while lighter contaminants float up to the water surface in the tube 13 * The floating contaminants are continuously discharged together with a certain amount of water through the upper portion of the conduit 28, serving as an overflow. The amount of water discharged corresponds to the quantity of fresh water supplied to the cistern 1 via the conduit 22, and constitutes about 7 of the amount of cleaned water recirculated through the apparatus. The heavier contaminants settled on the bottom 12a of the container 12 can be discharged from the container at selected occasions by lifting the conduit 28 in the way described above. The time during which the conduit is in a lifted positions and the time between lifts is determined by several factors, such as the shape and size of the cistern 1 and container 12, but is kept as short and as long, respectively, as possible to prevent a too great amount of water from being discharged simultaneously with the contaminants. Some decrease of the total amount of discharged water is obtained with the conduit lifted since no water is then discharged through the overflow at the upper end of the conduit. The embodiments of the invention described above and illustrated on the drawings can naturally be modified within the scope of the disclosures in the patent claims. The invention is thus only limited to what is set forth in the patent claims. '

Claims: CLAIMS 1. Apparatus for separating excrement and waste feed in a pisciculture cistern which is preferably continuously supplied with water recirculated through the cistern and apparatus, the apparatus including a container (5j 12) in which a first pipe 5 (6j 11 ) projects, so that the opening of -the pipe is under the - water level in the container and suitably at a distance from the central axis of the container, contaminated water being discharged into the container through said pipe, characterized in that a second substantially vertical pipe (7} 13) is arranged 10 inside the container and has a) a larger cross section than the first pipe, b) an upper end which is closed or opens out above the water surface in the conta er and c) a lower end which opens out between the. bottom of the container and said opening on the first pipe, in that a third discharge pipe (3$ 1 * 4J 24) 15 thrusts into the container and has a water discharging opening and that the openings of the first and third pipes (βj 11 and 3 14? 24) are separated from each other by a substantially vertical wall on the second pipe (7j 13) so that the water flow¬ ing out of the opening of the first pipe (6j 11 ) is forced to • 20 pass under said wall after separating from the contaminants settled on the bottom of the container and subsequently upwards before it is taken into the third pipe (3j 14j 24). 2. Apparatus as claimed in claim 1, characterized in that the container (5) is adapted inside the pisciculture cistern 25 and that the container and the first and second pipes (6, 7) form a unit removable from the cistern. 3. Apparatus as claimed in claim 2, characterized in that the third pipe (3) projects through the bottom of the cistern and through the bottom of the container (5) preferably centrally 30 therein. 4. Apparatus as claimed in claim 2 or 3> characterized in that the container (5) bottom rests on the bottom (1a) of the cistern (l), and that a narrow gap is defined between said bottoms, this gap giving connection to the lower end of the 35 first pipe (6). OMPI 5. Apparatus as claimed in any of the preceding claims, characterized in that the second pipe (7} 13) is attached in an eccentric position inside the container (5j 12) and that a portion of the cylindrical surface of the second pipe is attached to the inner surface of the container. 6. Apparatus as claimed in claim 1, characterized in that the container (12) is arranged outside the cistern (l) and that a vertical " tube (10) is arranged in the cistern, conta¬ minated water being passed through the lower end of said tube, the upper end of which is closed or situated above the water surface in the cistern (l), in that one end of a conduit (11) opens out in the tube (lθ) at a level under that of the water level in the cistern, the other end of the conduit (11), extend¬ ing into the container (12) and merging into said first pipe (11) the opening of which projects into the second pipe (13)« 7. Apparatus as claimed in claim 1 , characterized in that a substantially vertical conduit (28) mounted in the container (12) is displaceable from a first position in which its lower portion seals against a hole (26) in the bottom (12a) of the container and its upper part forms an overflow for water in the container, to a second position in which said hole is at least partially uncovered for discharging contaminants settled at the bottom of the container. 8. Apparatus as claimed in claim 7, characterized in that a part of the bottom (12a) of the container (12) surrounding said hole (26) is disposed lowest in -fche container and that the bottom of the container is preferably conical with the hole made at the vertex of the cone. 9. Apparatus as claimed in claim 7 or 8, characterized in that the lower part of the conduit (28) and/or the part of the bottom (12a) surrounding the hole (26) are provided with means for retaining and/or sealing the conduit relative to the portion of the container bottom surrounding the hole.

Inventors: STERNER K
Applicants: STERNER K
Application year: 1980
Main classification: B01D21
IPC codes: A01K63