Patent Publication Number: US-2021161108-A1

Title: Land-based fish rearing plant

Description:
FIELD OF THE INVENTION 
     The present invention relates to the technical field of land-based fish rearing plants. More specifically, in a broad sense, the invention comprises two large units (B, C) comprising oval main flow tanks (B, C) for grow-out fish, each with their own dedicated water treatment plants ( 4 B,  4 C) generally entirely arranged within the perimeter of the inner wall of the flow tanks, and a purge plant ( 12 ) arranged in between the oval flow tanks (B, C). Even more specifically, the invention comprises a postsmolt tank (A) also having its water treatment plant ( 4 A) generally entirely arranged within the perimeter of the inner wall of the flow tank ( 1 A) and arranged for feeding postsmolt large enough for transfer to the grow-out tanks. 
     BACKGROUND ART 
     WO 2014/183765 depicts a fish farming plant comprising a central tank and one or more surrounding tanks wherein the central tank is used for water treatment, and the one or more surrounding tanks are used for farming of fish, further comprising flow applicators, whereby the flow rate of the water in the surrounding tanks are individually independent of the water exchange rate, wherein the fish farming plant comprises several movable permeable section walls in each of the surrounding tanks dividing said tanks in tanks sections, each surrounding tank is equipped with one or two outlets and one or two inlets a, and a substantially horizontal/laminar flow structure of the water in each one of said one or more surrounding tanks is provided. 
     SHORT SUMMARY OF THE INVENTION 
     The current invention is a land-based fish rearing plant comprising: 
     A land-based fish rearing plant comprising:
         a postsmolt unit (A) comprising:
           an oval postsmolt flow tank ( 1 A) subdivided by a number (n) of transverse separation grids ( 2 A 1  to  2 An) into the number of (n) tank sections ( 3 A 1  to  3 An) for postsmolt cohorts of successively increasing sizes,   one or more main flow generators ( 9 A) for providing a main flow (ΦAmain) along a main flow path in said oval postsmolt flow tank ( 1 A),   one or more water outlets ( 7 A) for a partial flow from said oval postsmolt flow tank ( 1 A) to a first water treatment flow (ΦA RAS ) in a first water treatment plant ( 4 A) comprising piping arrangement ( 5 A) and pumps ( 6 A) and one or more direct water return inlets ( 8 A) to said postsmolt flow tank ( 1 A),   wherein said water treatment plant ( 4 A) is arranged within a perimeter of an inner wall ( 10 Ai) of said postsmolt flow tank ( 1 A),   
           at least two grow-out units (B, C) for growing salmon in the stages after said postsmolt stages, each grow-out unit (B, C) comprising:
           an oval grow-out flow tank ( 1 B,  1 C) for said growing salmon, subdivided by a number (m) of transverse separation grids ( 2 B 1  to  2 Bm,  2 C 1  to  2 Cm) into the number of (m) tank sections ( 3 B 1  to  3 Bm,  3 C 1  to  3 Cm) for growing salmon cohorts of successively increasing sizes,   one or more main flow generators ( 9 B,  9 C) for providing a main flow (ΦBmain, ΦCmain) along a main flow path in said oval grow-out flow tanks ( 1 B,  1 C), respectively   
           one or more water outlets ( 7 B,  7 C) for a partial flow from said oval grow-out flow tanks ( 1 B,  1 C) to second and third water treatment flows (ΦB RAS , ΦC RAS ) in second and third water treatment plants ( 4 B,  4 C) each comprising piping arrangements ( 5 B,  5 C) and pumps ( 6 B,  6 C) and one or more water return inlets ( 8 B,  8 C) to said grow-out flow tanks ( 1 B,  1 C), respectively, and
           wherein said second and third water treatment plants ( 4 B,  4 C) are arranged within a perimeter of an inner wall ( 10 Bi,  10 Ci) of said grow-out flow tanks ( 1 B,  1 C), respectively   
           a purge-unit ( 12 ) arranged between said grow-out units (B, C), wherein the last sections (m) in said grow-out units (B, C) are connected via lock-gates ( 14 B,  14 C) to an inlet channel ( 15 ) to two or more purge chambers ( 13   a ,  13   b , . . .  13   z ) for temporary holding and purging of the salmon prior to its slaughtering, wherein said purge-unit ( 12 ) comprises a fourth water treatment plant ( 16 ) and an export line ( 171 ) to a fish slaughterhouse ( 17 ).       

     In an embodiment of the invention is also a method for fish farming in a fish rearing plant: 
     A method for fish farming in a land-based fish rearing plant comprising:
         providing an oval postsmolt flow tank ( 1 A) and two grow-out flow tanks ( 1 B,  1 C);   running flow generators ( 9 A,  9 B,  9 C) to set up main flows in said flow tanks ( 1 A,  1 B,  1 C) respectively,   running and maintaining a cleaning water and pumps ( 6 A,  6 B,  6 C) in central water treatment plants ( 4 A,  4 B,  4 C) arranged within inner perimeters of said flow tanks ( 1 A,  1 B,  1 C);   having said sections ( 3 A 1 - 3 An) of said postsmolt tank ( 1 A) occupied with postsmolt and said sections ( 3 B 1 - 3 Bm) and ( 3 C 1 - 3 Cm) of said grow-out tanks ( 1 B,  1 C) occupied with grow-out salmon,   at given time intervals:   transferring a largest cohort of grow-out salmon alternately from one section ( 3 Bm,  3 Cm) of one of said grow-out tanks ( 1 B,  1 C) to an inlet channel ( 15 ) of one of said purge chambers ( 13   a ,  13   b , . . .  13   z ) for temporary holding and purging of the salmon,   for each tank section prior to said alternately grow-out salmon emptied tank section ( 3 Bm,  3 Cm) all the way down to said first section ( 3 B 1 ,  3 C 1 ), moving each said grow-out salmon cohort to a subsequent tank section,   moving/transferring a largest cohort of postsmolt over from a last section ( 3 An) of said postsmolt tank ( 1 A) over to at least one of said first sections ( 3 B 1 ,  3 C 1 ) in said grow-out flow tanks ( 3 B,  3 C),   for each tank section prior to section ( 3 An) of said postsmolt tank ( 1 A) all the way down to said first section ( 3 A 1 ), moving each postsmolt cohort to a subsequent tank section,   supplying a new postsmolt cohort to said first tank section ( 3 A 1 ) of said postsmolt tank ( 1 A).       

    
    
     
       FIGURE CAPTIONS 
       The attached figures illustrate some embodiments of the claimed invention. 
         FIG. 1  illustrates the invention comprising a postsmolt unit (A), two grow-out units (B and C) and a purge unit ( 12 ). The flow directions in the postsmolt tank and the grow-out tanks ( 1 A,  1 B,  1 C) are the same. Final sections ( 3 B 5 ,  3 C 5 ) “end up” at an exit line ( 16 ) to purge unit ( 12 ). Postsmolt is pumped from a final section ( 3 A 9 ) of the postsmolt flow tank ( 1 A) to first sections ( 3 B 1 ,  3 C 1 ) of the grow-out flow tanks ( 1 B,  1 C). 
         FIG. 2  illustrates an embodiment of the invention and is a perspective view of one of the postsmolt units A or the grow-out units B, C with a main flow postsmolt and grow-out flow tanks ( 1 A,  1 B,  1 C), respectively, and a water first, second and third water treatment plant ( 4 A,  4 B,  4 C) arranged entirely within the perimeter of the inner wall of the main flow tanks, respectively. 
         FIG. 3  illustrates an embodiment of the invention and is a plane view of one of the postsmolt unit (A) or the grow-out units (B or C), with the main flow postsmolt and grow-out flow tanks ( 1 A,  1 B,  1 C) and each water treatment plant ( 4 A,  4 B,  4 C) arranged within the perimeter of the inner wall of the main flow postsmolt and grow-out flow tanks ( 1 A,  1 B,  1 C), and shows major features such as the filter units ( 41 A), biofilm reactors ( 42 A), degassing units ( 43 A), main flow generators ( 9 A,  9 B,  9 C) arranged in the main postsmolt and grow-out flow tanks ( 1 A,  1 B,  1 C), respectively, and water outlets ( 7 A,  7 B,  7 C) arranged in transverse rows across the main flow at the bottom of the main flow tanks. The return inlets ( 8 A,  8 B,  8 C) from the water treatment plants are not detailed here. 
         FIG. 4  illustrates an embodiment of the invention and is a cross sectional view of one of the postsmolt unit (A) or the grow-out tanks (B or C), with the main flow postsmolt or grow-out flow tank ( 1 A,  1 B,  1 C) and the water treatment plant ( 4 A,  4 B,  4 C) within the perimeter of the inner wall of the main flow tank, respectively, and shows major features such as the filter units ( 41 A ( 41 B,  41 C)), biofilm reactors ( 42 A ( 42 B,  42 C)), degassing units with CO2 removal ( 43 A ( 43 B,  43 C)), water treatment flow pumps ( 6 A ( 6 B,  6 C)), outlets ( 7 A ( 7 B,  7 C)) from the flow tank, with transversal channels ( 71 A ( 71 B,  71 C)) and return inlets ( 8 A ( 8 B,  8 C)) to the flow tank, with transversal channels ( 81 A ( 81 B,  81 C)). The different water levels are depicted in the cross-sectional view showing successively the tank water level, drum filter water level, biofilm reactor water level and degassing unit water level with CO2 removal. 
         FIG. 5  illustrates an embodiment of the invention similar to  FIG. 3  but where the main flow generators ( 9 A,  9 B,  9 C) are placed outside their respective postsmolt and grow-out flow tanks ( 1 A,  1 B,  1 C) and having continuously, incrementally moving grids and sections ( 3 A 1 - 3 A 9 ,  3 B 1 - 3 B 5 , and  3 C 1 - 3 C 5 ) while moving each cohort with each section. In an embodiment of the invention there are arranged motors ( 18 A 1 ,  18 B 1 ,  18 C 1 ) connected to vertical shafts ( 19 ) on grids ( 2 A 1 - 2 An,  2 B 1 ,  2 BM,  2 C 1 ,  2 Cm) to pinion ( 20 ) to mesh with rack ( 21 A,  21 B,  21 C). The grids may be moved with different speeds in order to adjust section volume with cohort weight. 
         FIG. 6  illustrates the same embodiment as in  FIG. 4  with motors ( 18 A 1 ,  18 B 1 ,  18 C 1 ) connected to vertical shafts ( 19 ) on grids ( 2 A 1 - 2 Cm) to pinion ( 20 ) to mesh with rack ( 21 B,  21 B,  21 C). 
         FIG. 7  illustrates the purge tank ( 12 ) with its system to service two grow-out tanks ( 1 B and  1 C). Fish that are ready to be slaughtered are transferred from the main grow-out tanks ( 1 B,  1 C) into purge chambers ( 13   a ,  13   b , . . . ) through transfer gates between the tanks. Joint walls with the tanks (B and C) gives construction savings. 
         FIG. 8  illustrates an embodiment of the invention with external flow generators ( 9 A,  9 B,  9 C) located within a flow channel ( 92 A,  92 B,  92 C) with a grid ( 97 A,  97 B,  97 C), main flow outlets ( 91 Ao,  91 Bo,  91 Co) and return inlets ( 91 Ai,  91 Bi,  91 Ci). 
         FIG. 9  illustrates the method of transfer (shown as a matrix) within the postsmolt flow tank ( 1 A) sections ( 3 A 1  to  3 A 9 ) and the transferal of the largest cohort of postsmolt over from a last section ( 3 An) in postsmolt tank ( 1 A) over to at least one of the first sections ( 3 B 1 ,  3 C 1 ) in the grow-out flow tanks ( 3 B,  3 C), and further on to the purge tank ( 12 ). 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     The invention will in the following be described and embodiments of the invention will be explained with reference to the accompanying drawings. 
     The invention is a land-based fish rearing plant. The invention comprises two or more grow-out units (B, C) for rearing of the fish cohort&#39;s stages after the postsmolt stage, and a purge unit ( 12 ) arranged common to the grow-out units (B, C). Grown-out fish at about 4.2 kg is exported from the purge unit ( 12 ). The postsmolt is imported from a separate producer of smolt, or smolt is reared locally. The grow-out units (B, C) may be arranged transversely in a series of two, with the purge unit ( 12 ) placed between the grow-out units (B) and (C). The materially largest component of each unit is an oval grow-out flow tank ( 1 B,  1 C). Please see  FIG. 1  for the general overview. For forming an overview, the illustrated embodiment&#39;s grow-out flow tanks ( 1 B,  1 C) each have a longside length of 45 metres, an overall length of 80.4 metres, a total width of 35.4 metres, and a height of 6.5 metres and a water depth of 6 metres. The width of each “raceway”, the main flow channel in the grow-out tank ( 1 B,  1 C) is 8.2 metres. Thus, the contained water volume in each raceway, the grow-out tank ( 1 B) or ( 1 C) alone is about 9200 m3. Additionally, the centrally arranged water treatment plant ( 4 B,  4 C) of each unit (B, C) holds considerable amounts of water. Specific measures are given in the table below. Please notice that the embodiments described here are dimensioned for salmon post-smolt and grow-out cohorts, but with minor modifications could be adapted to other species such as trout, yellowtail kingfish, mahi mahi, grouper fish and others. 
     In an embodiment of the invention there is arranged a postsmolt unit (A) for rearing of the postsmolt fish cohorts. The postsmolt unit (A) comprises:
         Firstly, it has an oval postsmolt flow tank ( 1 A) for postsmolt, subdivided by a number (n) of transverse separation grids ( 2 A 1  to  2 An) and thus subdivided into the number (n) tank sections ( 3 A 1  to  3 An) for postsmolt cohorts of successively increasing sizes. In the illustrated embodiment there are nine tank sections. If inserted once a month, each cohort of postsmolt will reside nine months in the oval postsmolt flow tank ( 1 A) while growing. Please observe that if the below mentioned flow generators ( 9 A) are placed in the main flow, additional grids ( 2 Ap) must be arranged in order to prevent fish from being damaged or turbulence-affected by the flow generators, while if the flow generators is placed outside the postsmolt flow tank, please see  FIG. 5  and  FIG. 8 , there is no need for such an additional grid ( 1 Ap). The same relates to the grow-out tanks ( 1 B,  1 C).   Secondly, it has one or more main flow generators ( 9 A) for providing a main flow (ΦAmain) along a main flow path in the oval grow-out flow tank ( 1 A).   Thirdly, it has one or more water outlets ( 7 A) for a partial flow from the oval grow-out flow tank ( 1 A) to a first water treatment flow (ΦA RAS ) through a first water treatment plant ( 4 A) comprising piping arrangement ( 5 A) and pumps ( 6 A) and having one or more water return inlets ( 8 A) to said postsmolt flow tank ( 1 A).   Fourthly, the first water treatment plant ( 4 A) is arranged within the perimeter of an inner wall ( 10 Ai) of said postsmolt flow tank ( 1 A). Having generally the entire first water treatment plant ( 4 A) in the middle oval within the perimeter of the inner wall of the postsmolt flow tank ( 1 A) is highly advantageous due to the fact that piping and channels between the oval postsmolt flow tank ( 1 A) and the first water treatment plant ( 4 A) becomes short, thus requiring significantly less pumping energy and construction and material costs, surface cleaning, disinfection and maintenance costs compared to external water treatment plants. Prior art tanks having a water treatment plant subdivided into a internal and an external part relative to the raceway, such as having a particle filter and biofilter plant internal and a degassing plant external, would require much transport of water back and forth through passages below or above across the flow tank.   In the postsmolt unit (A) postsmolt flow tank ( 1 A) we will insert smolt cohorts, e.g. at intervals of one month, initially at the size of about 100 g, and rear in in the sections ( 3 A 1  to  3 An) up to a weight of about 1900 g.       

     In an embodiment of the invention, the largest cohort of the postsmolt tank ( 1 A) will be split into two (preferably) fractions and each fraction of the cohort will be moved over to the two grow-out flow tanks ( 1 B,  1 C). There may be further grow-out units (B, C) than two, but we have come to the conclusion that having two such grow-out units per one postsmolt unit is advantageous because the rather large purge unit ( 12 ) which shall serve both, is placed immediately between the grow-out units (B, C), please see  FIGS. 1, 5, 5, and 7 . 
     Each of the two grow-out units (B, C) for growing salmon in the stages after the postsmolt stages comprises:
         Firstly, an oval grow-out flow tank ( 1 B,  1 C) for said growing salmon. Each oval flow tank ( 1 B,  1 C) is subdivided by a number (m) of transverse separation grids ( 2 B 1  to  2 Bm,  2 C 1  to  2 Cm) and thus subdivided into the number (m) tank sections ( 3 B 1  to  3 Bm,  3 C 1  to  3 Cm) for growing salmon cohorts of successively increasing sizes.   Secondly, each grow-out unit (B, C) has one or more main flow generators ( 9 B,  9 C) for providing a main flow (ΦBmain, ΦCmain) along a main flow path in said oval grow-out flow tank ( 1 B,  1 C),   Thirdly, each grow-out flow tank ( 1 B,  1 C) has one or more water outlets ( 7 B,  7 C) for a partial flow from the oval grow-out flow tank ( 1 B,  1 C) to form water treatment flows (ΦB RAS ) (ΦC RAS ) a in the second and third water treatment plants ( 4 B,  4 C). The water treatment plants comprise piping arrangement ( 5 B,  5 C) and pumps ( 6 B,  6 C) and at least one water return inlet ( 8 B,  8 C) to the grow-out flow tanks ( 1 B,  1 C), please see  FIG. 4 .   Fourthly, the second and third water treatment plants ( 4 B,  4 C) is arranged within the perimeter of an inner wall ( 10 Bi,  10 Ci) of said grow-out flow tanks ( 1 B,  1 C), respectively, just as for the first water treatment plant ( 4 A) in the postsmolt unit (A). Having generally the entire water treatment plant ( 4 A,  4 B) in the middle oval within the perimeter of the inner wall of the grow-out flow tank ( 1 B,  1 C) is highly advantageous just as mentioned for the post-smolt unit ( 1 A) above.       

     A purge-unit ( 12 ) is arranged between said grow-out units (B, C), wherein the last sections (m) in said grow-out flow tanks ( 1 B,  1 C) of grow-out units (B, C), respectively are connected via lock-gates ( 14 B,  14 C) to an inlet channel ( 15 ) to two or more purge chambers ( 13   a ,  13   b , . . .  13   z ) for temporary holding and purging of the grown-out salmon cohorts prior to its slaughtering, wherein the purge-unit ( 12 ) comprises at least a fourth water treatment plant ( 16 ) and an export line to a fish slaughterhouse ( 17 ). In a preferred embodiment of the invention the number of purge chambers is 8, please see  FIG. 5 ,  FIG. 6 , and  FIG. 7 . 
     The invention is a land-based fish rearing plant. The more narrowly defined invention comprises a postsmolt unit (A) for rearing of the postsmolt fish cohorts, two or more grow-out units (B, C) for rearing of the fish cohort&#39;s stages after the postsmolt stages, and a purge unit ( 12 ) arranged common to the grow-out units (B, C). Grown-out fish at about 4.2 kg is exported from the purge unit ( 12 ). The postsmolt is imported from a separate producer of smolt, or smolt is reared locally. The units (A, B, C) may be arranged transversely in a series of three, with the purge unit ( 12 ) placed between units (B) and (C). The materially largest component of each unit is an oval flow tank ( 1 A,  1 B,  1 C) which are a postsmolt flow tank ( 1 A), and two grow-out flow tanks ( 1 B,  1 C). Please see  FIG. 1  for the general overview. For forming an overview, the illustrated embodiment&#39;s flow tanks ( 1 A,  1 B,  1 C) each have a longside length of 45 metres, an overall length of 80.4 metres, a total width of 35.4 metres, and a height of 6.5 metres and a water depth of 6 metres. The width of each “raceway” is 8.2 metres. Thus, the contained water volume in the raceway alone is about 9200 m3. Additionally, the centrally arranged first, second and third water treatment plant ( 4 A,  4 B,  4 C) of each unit (A, B, C), respectively, holds considerable amounts of water. Specific measures are given in the table below. Please notice that the embodiments described here are dimensioned for salmon post-smolt and grow-out cohorts, but with minor modifications could be adapted to other species such as trout, yellowtail kingfish, mahi mahi, grouper fish and others. 
     
       
         
           
               
               
               
             
               
                   
               
             
            
               
                 Length of longside 
                 45 
                 m 
               
               
                 Raceway width of postsmolt flow tank and 
                 8.2 
                 m 
               
               
                 grow-out flow tank 
               
               
                 Height of wall 
                 6.5 
                 m 
               
               
                 Wall thickness 
                 0.5 
                 m 
               
               
                 Water depth in raceway 
                 6 
                 m 
               
               
                 Inner diameter of raceway, i.e. wet surface 
                 18 
                 m 
               
               
                 of inner wall (10Ai) 
               
               
                 Overall raceway length of postsmolt and 
                 80.4 
                 m 
               
               
                 grow-out flow tank (1A, 1B, 1C) 
               
               
                 Overall width of flow tank 
                 35.4 
                 m 
               
               
                 Total flow tank volume 
                 9184 
                 m 3   
               
               
                 Floor tank bottom (10Ab, 10Bb, 10Cb) area 
                 1413 
                 m 2   
               
               
                 Wall area in flow tank (1A, 1B, 1C) 
                 2240 
                 m 2   
               
               
                 Total surface area of tank 
                 3653 
                 m 2   
               
               
                 Contained water volume in flow tank 
                 8478 
                 m 3   
               
               
                 Production volume (eks.propeller) if flow 
                 7500 
                 m 3   
               
               
                 generators present in main flow 
               
               
                 Hydraulic retention time in the flow tank 
                 30 
                 min 
               
               
                 Water volume reserved for propeller section, 
                 978 
                 m 3   
               
               
                 (if the main flow generator (9A, 9B, 9C) 
               
               
                 propeller are placed in the main flow tank 
               
               
                 (1A, 1B, 1C), respectively 
               
               
                 Length of tank sections for flow generators 
                 19.9 
                 m 
               
               
                 combined, if a number of two propellers/main 
               
               
                 flow generators 
               
               
                 Length of tank sections (3Ap, 3Bp, 3Cp) per 
                 9.9 
                 m 
               
               
                 propeller 
               
               
                   
               
            
           
         
       
     
     In an embodiment of the invention the number of tank sections ( 3 A 1 - 3 An) of the postsmolt flow tank ( 1 A) are between 6 and 10. As noted above, the number of separation grids ( 2 A 1 - 2 An) purely for separating the sections is the same number. If flow generators ( 9 A) are arranged in the main flow, one additional grid ( 2 Ap) is required for each flow generator in order to prevent damage to the fish. In an embodiment of the invention, please see  FIG. 1 , the number of tank sections ( 3 A 1 - 3 An) in the postsmolt flow tank is 9. 
     In the embodiment shown in  FIG. 1  the final tank sections ( 3 B 5 ,  3 C 5 ) of the grow-out flow tanks ( 1 B,  1 C) are facing the purge unit ( 12 ) in order for being adjacent to the channel ( 15 ) so as for making the transfer of fish feasible. In this embodiment one may say that grow-out flow tank ( 1 C) is a copy of grow-out flow tank ( 1 B) but rotated 180 degrees in the horizontal plane. Please also notice that in the illustrated embodiment shown in  FIG. 1  the overall shape and design of grow-out tanks B and C is the same as the overall shape of postsmolt tank A. 
     All water outlets ( 7 A,  7 B,  7 C) from the main flow of the flow tanks ( 1 A,  1 B,  1 C) to the first, second and third water treatment plants ( 4 A,  4 B,  4 C), respectively, must be provided with grids ( 77 A,  77 B,  77 C) in order to prevent fish from entering the water treatment plants. 
     In an embodiment the insert postsmolt cohort is 100 grams, and each cohort is fed until it has grown to about 1900 grams in section  3 An, i.e. section  3 A 9  after about 9 months. 
     In an embodiment of the invention, Oxygen supply ( 45 A) to the water may be installed in the water first water treatment plant ( 4 A). In another embodiment of the invention, the oxygen supply ( 45 A) may be installed directly in the postsmolt flow tank ( 1 A) because it advantageously could be operated by manual valves during undesired intermittent absence of electrical power. The same goes for Oxygen supply ( 45 B,  45 C) to the grow-out flow tanks ( 1 B,  1 C). 
     In an embodiment of the invention the first water treatment plant ( 4 A) comprises a number of filter units ( 41 A), a biofilm reactor ( 42 A), a degassing unit with CO2 treatment ( 43 A), and an Ozone treatment unit ( 44 A). In this way, the entire water treatment flow (ΦA RAS ) may occur within the perimeter of the inner, oval wall of the postsmolt flow tank ( 1 A), which advantageously thus may have a short flow path. Similar considerations are valid for the second and third water treatment plants with regard to the grow-out flow tanks ( 1 B,  1 C). 
     In an embodiment of the invention, there is a number of separation grids ( 2 Bm and  3 Bm) and sections ( 2 Cm and  3 Cm) in said grow-out unit&#39;s (B, C) oval flow tank ( 1 B,  1 C) between 3 and 7. In a further embodiment the number is 5. This makes the retention time for each cohort in the grow-out units to be five months if the interval between the insert cohorts is one month as above described. The cohort from the post-smolt stage is split into one half distributed to each first grow-out tank ( 1 B,  1 C) first section ( 3 B 1 ,  3 C 1 ) when moved. At this stage each half of the cohort are of the same size and weight unless sorted. One may sort them, but in an embodiment of the invention the temperatures in the grow-out tanks are kept different in order for the two parallel cohorts to grow differently so as for the two initially parallelly introduced cohorts to be harvested with the half interval, i.e. transferred with two weeks interval to the purge unit ( 12 ). 
     In an embodiment of the invention the grow-out unit&#39;s (B, C) grow-out flow tank ( 1 B,  1 C) is arranged for holding grow-out salmon in the size range 1900-4300 g. 
     In an embodiment of the invention the grow-out unit&#39;s (B, C) water treatment plant ( 4 B and  4 C) comprise filter units ( 41 B,  41 C), a biofilm reactor ( 42 B,  42 C), a degassing unit with CO2-removal ( 43 B,  43 C), and an Ozone treatment unit ( 44 B,  44 C), respectively. 
     In an embodiment of the invention the postsmolt flow tank&#39;s ( 1 A) flow generator ( 9 A) providing the main flow (ΦAm) is arranged in the main flow path of the oval postsmolt tank ( 1 A). In this embodiment it may have the form of a propeller axially aligned with the main flow path along the oval tank, please see  FIGS. 1, 3, and 6 . 
     In another embodiment of the invention the postsmolt tank&#39;s ( 1 A) flow generator ( 9 A) providing said main flow (ΦAm) is arranged outside the flow tank ( 1 A) as such, i.e. inside the perimeter of the inner wall ( 10 Ai), outside the perimeter of an outer wall ( 10 Ao), please see  FIG. 5 , or below the bottom ( 10 Ab) in relation to the main flow path in said oval flowtank ( 1 A). Please see  FIG. 8  for the embodiment of the flow generator ( 9 A) arranged outside the oval flowtank ( 1 A). Similar arrangements may be made for each the grow-out flow tanks ( 1 B,  1 C), please see  FIG. 5 . In this case the water may be taken out through main flow outlets ( 91 Ao ( 91 Bo,  91 Co)) to a flow generator ( 9 A ( 9 B,  9 C)) such as a propeller or impeller arranged in a tunnel ( 92 A ( 92 B,  92 C)) and a return inlet ( 91 Ai ( 91 Bi,  91 Ci)) back to the main flow path in the flow tank ( 1 A ( 1 B,  1 C)). In such embodiments the main flow outlets ( 91 Ao ( 91 Bo,  91 Co)) must be provided with a grid ( 97 A ( 97 B,  97 C)) in order to prevent fish from entering the tunnel ( 92 A ( 92 B,  92 C)) to avoid being killed in the flow generator ( 9 A ( 9 B,  9 C)). The number of flow generators and flow tunnels needs to be adapted and calculated for each specific application. 
     Advantageously said outlets and inlets ( 91 Ao,  91 Ai) are designed with low-angled inlet and outlet passages in order to minimize energy loss, please see  FIG. 8  for illustration. In an embodiment of the invention the flow generators ( 9 A) shall maintain an overall water flow velocity of 0.4 m/s for the main flow (ΦAm) for the postsmolt cohorts. We consider the embodiment as shown in  FIG. 8  and explained above in this paragraph, with a flow tank ( 1 A,  1 B,  1 C) with the described and illustrated flow generator ( 9 A,  9 B,  9 C) arranged outside the flow tank, as an independent invention in itself. 
     In an embodiment of the invention, the flow generators ( 9 B,  9 C) of the oval grow-out flow tanks which provide the main flow (ΦBmain, ΦC main) are arranged in the main flow path of the oval flow tanks ( 1 B,  1 C). 
     By placing the flow generators ( 9 B,  9 C) in the main flow path of the oval flow tanks ( 1 B,  1 C) one can provide and optimize the flow path which in turn ensures reduced pumping and pressure loss in the system, thus reducing the total power consumption. In this embodiment it may have the form of a propeller axially aligned with the main flow path along the oval tank. 
     In an embodiment of the invention, the flow generators ( 9 B,  9 C) which provide the main flow (ΦBmain, ΦC main) in the grow-out flow tanks are arranged within the circumference of the inner wall ( 10 Bi,  10 Ci), or outside the circumference of the outer wall ( 10 Bo,  10 Co), please see  FIG. 5 , or below the bottom ( 10 Bb,  10 Cb) in relation to the main flow path of the oval flow tank ( 1 B,  1 C). Having the flow generators placed outside of and external to the oval flow tanks ( 1 B,  1 C) will reduce the potential of fish getting damaged or killed by the flow generator propellers. Also, by placing the flow generators outside of the oval flow tanks ( 1 B,  1 C) it is much simpler to produce a laminar main flow geometrically through piping and/or ducting. A laminar and uniform flow is beneficial for the fish&#39;s wellbeing and growth. In such case the water may be taken out through main flow outlets ( 91 Bo,  91 Co) to a flow generator ( 9 B,  9 C) such as a propeller or impeller arranged in at least one tunnel ( 92 B,  92 C) and at least one return inlet ( 91 Bi,  92 Ci) back to the main flow path in the grow-out flow tank ( 1 B,  1 C). 
     The number of flow generators and flow tunnels needs to be adapted and calculated for each specific application. In such embodiments the main flow outlets ( 91 Bo,  91 Co) must be provided with a grid ( 97 B,  97 C) in order to prevent fish from entering the tunnel ( 92 B,  92 C) to avoid being killed in the flow generator ( 9 B,  9 C). 
     In an embodiment of the invention, the number of the purge chambers ( 13   a ,  13   b , . . .  13   z ) is between four and ten. 
     In another embodiment of the invention, the number of the purge chambers ( 13   a ,  13   b , . . .  13   z ) is eight. 
     A preferred configuration will be to use six of the eight purge chambers and have two as spare, whereas the spare chambers will function as a buffer reservoir. This buffer can be beneficial if e.g. there is a price drop in the market that requires the fish farming plant to hold back a certain amount of grow-out salmon for awaiting the spot market price to rise. Another benefit to having spare capacity in the purge chamber is if there are intermittent problems or technical issues with the delivery to the fish slaughtering plant. The additional chambers will in this instance act as a buffer until the fault has been rectified with respect to the fish slaughtering plant. 
     In an embodiment of the invention, the water level in said postsmolt unit (A) decreases successively from the oval postsmolt flow tank ( 1 A) to said filter unit ( 41 A), to said biofilm reactor ( 42 A) and further to said degassing unit with CO2 treatment ( 43 A), please see  FIG. 4 . 
     In another embodiment of the invention, the water level in each of the oval grow-out units (B, C) decreases successively from the oval flow grow-out flow tanks ( 1 B,  1 C) to said filter units ( 41 B,  41 C), to said biofilm reactor ( 42 B,  42 C) and further to said degassing unit with CO2 treatment ( 43 B,  43 C). By utilizing a gravity flow in the water treatment section, i.e. the height differences between the oval flow tanks, the filter units, the biofilm reactor and degassing unit with CO2 treatment there is only a need for one step to pump the last portion of the treated water from the degassing unit with CO2 treatment back to the oval flow tank ( 1   b ,  1 C). Thus, reducing the power consumption in the pump(s). 
     In an embodiment of the invention, wherein a water outlet ( 7 A) for the water treatment flow (ΦA RAS ) to the first water treatment plant ( 4 A) is arranged in the bottom ( 10 Ab) of the oval postsmolt flow tank ( 1 A). 
     Having the water outlet ( 7 A) (an outlet as seen from the grow-out tank) for the water treatment flow arranged in the bottom of the oval flow tank ( 1 A) is advantageous since it will be more efficient to extract debris, feces, from the main flow into the water treatment flow as these elements tend to accumulate at the bottom of the tank. 
     In an embodiment of the invention, the water treatment flow (ΦA RAS ) from the water treatment plant ( 4 A) is pumped back to the oval flow tank ( 1 A) via a water return inlet ( 8 A) that is arranged through at least one or more of the inner walls ( 10 Ai), the outer wall ( 10 Ao) or the bottom ( 10 Ab) of the oval flow tank ( 1 A). 
     By having the option of different configurations for the water return ( 8 A) one can tune and adjust the return flow in such a manner to reduce the back pressure and power consumption of the pump ( 6 A). 
     In an embodiment of the invention, the water outlet ( 7 A) of the water treatment flow (ΦA RAS ) is co-current with the main flow (ΦAmain). By having the water outlet ( 7 A) co-current with the main flow one is able to reduce the pressure loss in the water treatment flow. 
     In an embodiment of the invention, the water outlet ( 7 A) forms an angle of 30 degrees with the bottom ( 10 Ab). 
     In an embodiment of the invention, wherein the number of water outlets ( 7 A) is two, three or more and the water outlets ( 7 A) are generally arranged in transversal rows. Reference is made to  FIG. 3  and  FIG. 4 . 
     In an embodiment of the invention, the water outlet ( 7 A) is connected to a transversal channel ( 71 A) where the transversal channel ( 71 A) extends from below the bottom ( 10 Ab) and to within the perimeter of the inner wall ( 10 Ai) and to the filter units ( 41 A). 
     In an embodiment of the invention, the water return inlet ( 8 A) of the water treatment flow (ΦA RAS ) is co-current with the main flow (ΦAmain). 
     In an embodiment of the invention, the water return inlet ( 8 A) forms an angle of 30 degrees with the bottom ( 10 Ab). 
     In an embodiment of the invention, the number of water return inlets ( 8 A) is two, three or more, and the water return inlets ( 8 A) are generally arranged in a transversal row. 
     In an embodiment of the invention, a transversal channel ( 81 A) extends from the pump ( 6 A) and outwards from the bottom ( 10 Ab) to outwards of the inner wall ( 10 Ai) to the water return inlet ( 8 A). Reference is made to  FIG. 4 . 
     An advantage of this embodiment is that the transversal channel ( 81 A) may have a low profile which requires less ground and civil work during the construction of the tank unit (A). 
     In an embodiment of the invention, the water outlet ( 7 B,  7 C) for the water treatment flow (ΦB RAS , ΦC RAS ) for the water treatment plant ( 4 B,  4 C) is arranged in the bottom ( 10 Bb,  10 Cb) of the oval flow tank ( 1 B,  1 C). The advantage of having the water outlet ( 7 B,  7 C) arranged at the bottom ( 10 Bb,  10 Cb) of the oval grow-out flow tank ( 1 B,  1 C) is that it will drain out the water comprising the precipitated particles flowing along the bottom layers of the water. 
     In an embodiment of the invention, the water outlet ( 7 B,  7 C) of the water treatment flow (ΦB RAS ) (ΦC RAS ) is co-current with the main flow (ΦBm, ΦCm). 
     In an embodiment of the invention, the water outlet ( 7 B,  7 C) forms an angle of 30 degrees with the bottom ( 10 Bb,  10 Cb). The advantage of the above embodiment is that the flow energy loss at the outlet is reduced, which may otherwise result in a reduced turbulence in and around the water outlet ( 7 B,  7 C). 
     In an embodiment of the invention, the water outlet ( 7 B,  7 C) leads to a transversal channel ( 71 B,  71 C) where the transversal channel ( 71 A) extends from below the bottom ( 10 Bb,  10 Cb) and to within the perimeter of the inner wall ( 10 Bi,  10 Ci) and to the filter units ( 41 B,  41 C), please see  FIG. 4 . In an embodiment of the invention, the filter units ( 41 B,  41 C) are rotating drum filters with continuous flushing and removal of filtered-out particles which are subject to further treatment and drying. 
     In an embodiment of the invention, the number of water outlets ( 7 B,  7 C) is two, three or more, and the water outlets ( 7 B,  7 C) are generally arranged in a transversal row across the entire width of the grow-out flow tanks ( 1 B,  1 C), reference is made to  FIG. 2 ,  FIG. 3  and  FIG. 4 . 
     In the embodiment shown in  FIG. 3  there are seven water outlets ( 7 A,  7 B,  7 C) in the transversal row extending across the entire width of both the postsmolt and the grow-out flow tanks ( 1 A,  1 B,  1 C). 
     In an embodiment of the invention, the water treatment flow (ΦB RAS ) (ΦC RAS ) from the second and third water treatment plants ( 4 B,  4 C) are pumped back to the oval grow-out flow tanks ( 1 B,  1 C), respectively via water return inlets ( 8 B,  8 C) arranged through at least one or more of the inner walls ( 10 Bi,  10 Ci) or the bottom ( 10 Bb,  10 Cb) (see  FIG. 4 ) of the oval grow-out flow tanks ( 1 B,  1 C), reference is made to  FIG. 2 ,  FIG. 3  and  FIG. 4 . In an embodiment of the invention, the water return inlet ( 8 B,  8 C) forms an angle of 30 degrees with the bottom ( 10 Ab). 
     In an embodiment of the invention, the number of the water return inlets ( 8 B,  8 C) is two, three or more, and the water inlets ( 7 B,  7 C) are generally arranged in transverse rows. An advantage of the above water return inlets ( 8 B,  8 C) is that they effectively contribute to maintaining the main grow-out water flow (ΦBmain, ΦCmain). 
     In an embodiment of the invention, a transversal channel ( 81 B,  81 C) extends from the pump ( 6 B,  6 C) and out below the bottom ( 106   b ,  10 Cb) and to outside the perimeter of the inner wall ( 10 Bi.  10 Ci) and to one or more of the water return inlets ( 8 B,  8 C). An advantage of this arrangement is that the transversal channel ( 81 B,  81 C) may have a low profile which requires less ground work during the construction of the tank units (B, C). 
     In an embodiment of the invention, the fourth water treatment plant ( 16 ) for the purge unit ( 12 ) comprises a fresh water intake line ( 161 ) and a discharge line ( 168 ) to the second and third water treatment plants ( 4 B,  4 C). 
     In a further embodiment of the invention, the fourth water treatment plant ( 16 ) includes a freshwater intake line ( 161 ) and a discharge line ( 169 ) to the water treatment plant ( 4 A) of the grow-out tank (A). The freshwater intake line ( 161 ) may be from a river, a lake, a well, a municipal water utility line, or the sea, or a combination of the above. The main advantage of having a separate freshwater intake line is that all of the incoming water supply to the entire plant may be controlled, filtered and UV-treated in order to prevent contamination from the environment. 
     In an embodiment of the invention, the water treatment plant ( 16 ) comprises filter units ( 162 ), a degassing unit with CO2 treatment ( 163 ) and ozone treatment unit ( 164 ). In an embodiment of the invention, there may be an Oxygen supply ( 165 ) to the circuit of the water treatment plant ( 16 ) which is automatically controlled, or the Oxygen supply ( 165 ) may be directly connected to the purge chambers ( 13   a ,  13   b , . . .  13   z ) and also manually controlled in order to enable operation also during an electrical black out. 
     In an embodiment of the invention, the water level in the purge units ( 12 ), the fourth water treatment plant ( 16 ) is successively decreasing from the purge chambers ( 13   a ,  13   b , . . .  13   z ) to the filter unit ( 162 ), to the degassing unit with CO2 treatment ( 163 ), further to the UV-treatment unit ( 166 ) and to the pumps ( 167 ) wherein the pumps ( 167 ) pump water back up to a level corresponding to the water level in the purge chambers ( 13   a ,  13   b , . . .  13   z ). 
     In an embodiment of the invention, the water level in the purge chambers ( 13   a ,  13   b , . . .  13   z ) is kept at a higher level than in the water flow tanks ( 1 B,  1 C). Keeping the water level in the purge chambers at a higher level than in the water flow tanks has two advantages. One advantage is that it is easier to let the fish swim against the current from the last grow-out section ( 3 Bm,  3 Cm) via the inlet channel ( 15 ) to the purge chambers ( 13 ). The second advantage is that we can hinder/prevent contamination from the flow tanks ( 3 B,  3 C) to the purge unit ( 12 ) in case an outbreak of disease occurs in the considerably larger flow tanks ( 3 B,  3 C). 
     In an embodiment of the invention, transfer lines ( 11 B,  11 C) from the postsmolt tank (A), please see  FIG. 1 , comprise a fish pump ( 110 ), a flexible hose ( 1116 ,  111 C) to a separation grid ( 112 B,  112 C) which further leads the fish to the first section ( 361 ,  3 C 1 ) in each of the grow-out flow tanks ( 3 B,  3 C). The separation grid ( 112 B,  112 C) will act as a dry spacer and as a barrier between the mentioned tanks. It will be flanged between the last portion of the flexible hose and the inlet of the first section. Using a separation grid ( 112 B,  112 C) between the flexible hose and the first section ( 361 ,  3 C 1 ) may reduce the potential of transferring diseases with the water from the postsmolt tank (A) to the grow-out flow tanks ( 3 B,  3 C) as there is little fluid transfer between the tanks, just fish. The drained water from the separation grid ( 112 B,  112 C) may be returned to the postsmolt tank (A) or made subject to water treatment and then returned to the postsmolt tank (A) or released to the environment. 
     In an embodiment of the invention, a fish counting device ( 113 ) is provided in the transfer lines ( 11 B,  11 C). The fish counting device will ensure that only the planned amount of fish will be transferred from the postsmolt tank (A) to each of the first sections ( 361 ,  3 C 1 ) in each of the grow-out flow tanks ( 1 B,  1 C). If the fish cohort shall only be distributed evenly between the two first sections ( 361 ,  3 C 1 ), the fish counting device ( 113 ) may be used to check the number of fish transferred to each section. The fish counting device ( 113 ) can either be placed upstream or downstream said fish pump ( 110 ) all depending upon location and required ease of maintenance for the fish counting device ( 113 ) and/or fish pump ( 110 ). 
     In an embodiment of the invention, the transverse separation grids ( 2 A 1 - 2 An,  2 B 1 - 2 Bm,  2 C 1 - 2 Cm) are motorized and movable along their associated flow tanks ( 1 A,  1 B,  1 C). 
     In another embodiment of the invention, the separation grids ( 2 A 1 - 2 An,  2 B 1 - 2 Bm,  2 C 1 - 2 Cm) are movable via a motor ( 18 A 1 ,  1861 ,  18 C 1 ) connected to a vertical shaft ( 19 A 1 ,  1961 ,  19 C 1 ) down to a pinion or gear ( 20 A 1 ,  2061 ,  20 C 1 ) that is in mesh with a rack ( 21 A 1 ,  21131 ,  21 C 1 ) that extends along the bottom ( 10 Ab,  106   b ,  10 Cb) of the oval flow tank ( 1 A,  1 B,  1 C). 
     By individually regulating the position of the transverse separation grids ( 2 A 1 - 2 An,  2 B 1 - 2 Bm,  2 C 1 - 2 Cm) one can control the segment length, i.e. segment volume of each tank, thereby establishing the necessary volume for the actual amount and size range of the fish cohort in question. 
     In an embodiment of the invention, at least one of the separation grids ( 2 A 1 - 2 An,  2 B 1 - 2 Bm,  2 C 1 - 2 Cm) comprises a gate ( 21 A 1 ,  21 B 1 ,  21 C 1 ), where said gate ( 21 A 1 ,  21 B 1 ,  21 C 1 ) is movable for forced displacement of fish from one section to the other sections ( 3 A 1  to  3 Am or  3 B 1  to  36   m  or  3 C 1  to  3 Cm). 
     In an embodiment of the invention, the flow generator ( 9 A,  9 B,  9 C) that provides the main flow (ΦAm, ΦBm, ΦC m) is arranged within the perimeter of the inner wall ( 10 Ai,  10 Bi,  10 Ci), or outside the perimeter of the outer wall ( 10 Ao,  10 Bo,  10 Co), or below the bottom ( 10 Ab,  10 Bb,  10 Cb) in relation to the main flow path in the oval flowtank ( 1 A,  1 B,  1 C) wherein the grids ( 2 A 1 - 2 An), ( 2 B 1 - 2 Bm), ( 2 C 1 - 2 Cm) are movable to any position within the flow tank ( 1 A,  1 B,  1 C) so as for moving each cohort gradually towards the outlet for fish from the tank instead of moving the fish across a grid. 
     The advantage with this configuration is that sections ( 3 A 1  to  3 An or  3 B 1  to  3 Bm or  3 C 1  to  3 Cm) successively change roles, in such a manner that  3 A 1  takes the role of  3 A 2 ,  3 A 2  takes the role of  3 A 3  etc. until when  3 A 9  is emptied (or discharged) with its dedicated grown cohort,  3 A 9  continues onward and becomes  3 A 1 , is filled up with a new smolt cohort and repeats the above mentioned sequence. In this way each cohort will stay in a dedicated section and grow from 100 grams to 1900 grams during the rotational sequence in each tank (A, B, C). During this growth sequence each grid ( 2 A 1 - 2 An), ( 2 B 1 - 2 Bm), ( 2 C 1 - 2 Cm) are movable to any position within the flow tank ( 1 A,  1 B,  1 C) to allow for the cohort growth rate. 
     
       
         
           
               
            
               
                   
               
               
                 Component List 
               
            
           
           
               
               
            
               
                 Component 
                 Description 
               
               
                   
               
               
                 A, B, C 
                 Postsmolt unit, Grow-out units 
               
               
                 ΦAMAIN, ΦBMAIN, 
                 Main flow A, B, C in oval flow tanks, postsmolt 
               
               
                 Φ CMAIN 
                 and grow-out tanks 
               
               
                 ΦARAS, ΦBRAS, 
                 Flow through water treatment plant 4A, 4B, 4C 
               
               
                 Φ CRAS 
                 first, second, third 
               
               
                 1A, 1B, 1C 
                 Oval flow tanks, 1A postsmolt flow tank, 1B, 
               
               
                   
                 1C grow-out flow tanks 
               
               
                 2A1-2An 
                 Transverse separation grids no. 1 to n 
               
               
                 3A1-3An 
                 Tank sections of postsmolt unit 
               
               
                 2B1-2Bm 
                 Transverse separation grids no. 1 to m 
               
               
                 3B1-3Bm 
                 Tank sections of grow-out unit 
               
               
                 2C1-2Cm 
                 Transverse separation grids no. 1 to m 
               
               
                 3C1-3Cm 
                 Tank sections of grow-out unit 
               
               
                 4A, 4B, 4C 
                 Water treatment plants first, second and third 
               
               
                 5 
                 SPARE 
               
               
                 6A, 6B, 6C 
                 Pumps in water treatment plants 
               
               
                 7A, 7B, 7C 
                 Water outlets from oval flow tanks to first, 
               
               
                   
                 second and third water treatment plants, resp. 
               
               
                 8A, 8B, 8C 
                 Water return inlets from water treatment plants 
               
               
                   
                 to oval flow tanks 
               
               
                 9A, 9B, 9C 
                 Main flow generators for flow tanks, postsmolt 
               
               
                   
                 flow tank and grow-out flow tanks 
               
               
                 10Ai, 10Bi, 10Ci 
                 Inner walls of flow tanks 
               
               
                 10Ab, 10Bb, 10Cb 
                 Bottom of flow tanks 
               
               
                 10Ao, 10Bo, 10Co 
                 Outer walls of flow tanks 
               
               
                 11B, 11C 
                 Transfer line from postsmolt chamber 3An to 
               
               
                   
                 grow-out chamber 3B1, 3C1 
               
               
                 12 
                 Purge unit after grow-out chamber 3Bm and 
               
               
                   
                 3Cm 
               
               
                 13 
                 Purge chamber 1 to 8 in purge unit 
               
               
                 14B, 14C 
                 Lock gates from grow-out chamber 3Bm and 
               
               
                   
                 3Cm to inlet channel 15 
               
               
                 15 
                 Inlet channel to purge unit 
               
               
                 16 
                 Fourth water treatment plant for purge unit 
               
               
                   
                 and for fresh intake water line 161 
               
               
                 17 
                 Slaughter house 
               
               
                 18A1, 18B1, 18C1 
                 Motor 
               
               
                 19A1, 19B1, 19C1 
                 Vertical shaft 
               
               
                 20A1, 20B1, 20C1 
                 Pinion 
               
               
                 21A, 21B, 21C 
                 Rack 
               
               
                 22A1, 22B1, 22C1 
                 Gate 
               
               
                 41A, 41B, 41C 
                 Filter unit, drum filter 
               
               
                 42A, 42B, 42C 
                 Biofilm reactor 
               
               
                 43A, 43B, 43C 
                 Degassing unit with CO2 treatment 
               
               
                 44A, 44B, 44C 
                 Ozone treatment unit 
               
               
                 45A, 45B, 45C 
                 Oxygen supply 
               
               
                 71A, 71B, 71C 
                 Transversal channel 
               
               
                 81A, 81B, 81C 
                 Transversal channel 
               
               
                 91Ao, 91Bo, 91Co 
                 Main flow outlet to external flow generators 
               
               
                 91Ai, 91Bi, 91Ci 
                 Return inlet 
               
               
                 92A, 92C, 92C 
                 Main flow generator tunnel 
               
               
                 97A, 97B, 97C 
                 Grid for main flow generator tunnel 
               
               
                 110 
                 Fish pump 
               
               
                 111B, 111C 
                 Flexible hose 
               
               
                 112B, 112C 
                 Separation grid 
               
               
                 113 
                 Fish counting device 
               
               
                 161 
                 Fresh water intake line 
               
               
                 162 
                 Filter units 
               
               
                 163 
                 Degassing unit with CO2 treatment 
               
               
                 164 
                 Ozon water treatment unit 
               
               
                 165 
                 Oxygen supply 
               
               
                 168 
                 Discharge line to water treatment plant 
               
               
                 169 
                 Discharge line to water treatment plant 
               
               
                 171 
                 Export line