Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/02—Aerobic processes
  • C02F3/06—Aerobic processes using submerged filters
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01K—ANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
  • A01K63/00—Receptacles for live fish, e.g. aquaria; Terraria
  • A01K63/04—Arrangements for treating water specially adapted to receptacles for live fish
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W10/00—Technologies for wastewater treatment
  • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

• the invention concerns a fish cultivation tank of the type described in Claim of Patent 1, for the production of smolt or fish for consumption.
• the cage systems currently used in fish farms also suffer from a number of drawbacks. Since a cage is an open system one is dependent on the natural variations in water temperature and water quality in general. Poor feed utilization results in sludge under the cages, which is detrimental to the environment for the fish. Fish have been destroyed by jellyfish, algae, microorganisms as well as low water temperatures. A closed unit with land-based tanks or sealed cages based on the present invention will reduce these problems connected with the environment and disease whilst increasing feed utilization and the growth of the fish.
• the main purpose of the invention is to create a unit which utilizes all the advantages associated with water recirculation.
• the unit is very simple, inexpensive to manufacture and requires minimal maintenance.
• the objective is to minimize labour costs, water consumption/discharge and the heating requirements, so that fish can be farmed at a lower cost than at present.
• the invention offers all the advantages of a closed plant for fish farming applications.
• Figs. 1-3 respectively show a vertical section (A) and a plane overhead perspective (B) of three means of designing a fish tank in accordance with the present invention.
• the design shows a fish tank 11 with a regular octagonal or circular horizontal section and a bottom 12 which inclines towards a sunken area 13.
• a cylindrically- shaped chamber 14 which has an equivalent octagonal or circular horizontal section, without a top or bottom.
• a biological filter or “biofilter” 15 is located in the chamber 14 to remove pollution from the water.
• the biofilter 15 consists of a thin-walled, plastic medium with a large specific surface which can be used to provide a surface for the cultivation of specified types of microorganisms.
• a fan or air pump 16 is connected to a pipe 17 which supplies air to the bottom of the biofilter, where it is spread by means of nozzles or diffusers 18.
• This air injection creates a rising column of water in the biofilter 15. This means that water is pumped from the lower area of the tank, through the biofilter and led from here back into the tank, thus the biofilter acts as an air lift pump and hereby provides internal cleansing and water recirculation.
• the water that flows through the biofilter at the top of the filter chamber 14 is led along a horizontal channel 19 and down a perforated distribution pipe 20.
• a disposable filter bag 21 can be located inside the distribution pipe 20. This filter could be made of textile and has the function of removing particles from the water before they flow out of the distribution pipe 20 into the tank.
• a cone 22 which has the function of creating eddies, in addition there is a horizontal outlet pipe 23 with a magnetic valve 24 controlled by a timer .
• This valve ensures that particles are removed from the sunken area 13, which forms a pocket where sludge can collect.
• the magnetic valve can be replaced by a suction pipe from a pump placed above the level of the water.
• a supply pipe 25 is used for water replenishment, this has a valve 26 which is controlled by a water- level sensor 27.
• Leading vertically downwards from the valve 26 is an inlet pipe 28. This pipe is perforated and located close to the wall of the tank.
• the filter chamber 14 is closed at the bottom by a grid 29 which allows the water through its mesh to the biofilter 15. The mesh prevents fish from entering this area.
• the filter chamber 14 ' has a double wall on two opposite sides, 31 and 32 respectively. This creates two overflow slits 33 and 34 which are connected by pipes 35 and 36 to two perforated vertical distribution pipes 37 and 38.
• a meshed grid 39 is located between the main part of the bottom 12' and the filter chamber 14', the mesh permits particles to pass through but hinders fish from entering the sludge pocket 13 '.
• Fresh water is supplied by two supply pipes 40 and 41 to below the vertical distribution pipes 37 and 38, these are controlled in a similar way to the example above.
• Fig. 3 presents a design which is intended for use in existing fish tanks.
• the reference numbers are once again the same as in Fig. 1.
• the main difference with this design is the construction of the central filter unit 42.
• Two guide plates 45 and 46 extend outwards as continuations of the respective walls. These will enable the recirculated water to flow into the fish tank from two sides of the filter chamber without requiring transfer pipes.
• the biological filter 15 will remove unwanted pollutants from the water such as primary organic matter and ammonia.
• the object of forcing the water outwards from the central filter element into the peripheral areas of the tank is to get the water in the tank into circular motion.
• the quantity of recirculated water can be altered by varying the air flow and the water level so as to regulate the water velocity in the tank at an optimal value for a specific type and size of fish.
• the biofilter is a lightweight, plastic medium with a large specific surface. If the design is correct, the biofilter will produce a culture of microorganisms which can break down organic matter and ammonia in the water.
• the ammonia is excreted by the fish and will exist in water in chemical equilibrium with unionized ammonia.
• Unionized ammonia is toxic for fish even in extremely low concentrations (25 ⁇ g/1).
• the oxygen that the fish and these microorganisms consume is balanced by the incoming airstream.
• the invention has devised a simple way to reuse the heated water, which is straightforward in terms of size and operation.
• Operational costs are primarily connected to the running cost of the air blower. If the degree of recirculation is very high and the incoming water has low alkalinity, it may be necessary to add a base to the water.
• the invention can theoretically restrict the spread of diseases to only the tank with the infected fish.
• a fan or air blower is the only piece of powered equipment required by the system. This makes it economically feasible to have a reserve power unit, thus making the system extremely reliable.
• Another matter is if there is a failure in the supply of water from the outside, with the present invention it will take a long time before any damage is caused. Similarly, periods with poor water quality in the incoming water will be cancelled out and counterbalanced in the tank.
• the practical design of the tank and the filter element in the example can be varied considerably.
• the system can also be used for fish farming in seawater, either using a tank on land or a closed cage where the biofilter is placed centrally in the cage as described above.

Applications Claiming Priority (2)

Publications (1)

Family

ID=19890017

Family Applications (1)

Country Status (2)

Cited By (12)

Citations (4)

• 1987
  • 1987-06-12 NO NO872452A patent/NO872452D0/no unknown
• 1988
  • 1988-06-07 WO PCT/NO1988/000050 patent/WO1988009615A1/en unknown

Patent Citations (4)

Non-Patent Citations (1)

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