IE83848B1 - Aquaculture - Google Patents
Aquaculture Download PDFInfo
- Publication number
- IE83848B1 IE83848B1 IE2000/0821A IE20000821A IE83848B1 IE 83848 B1 IE83848 B1 IE 83848B1 IE 2000/0821 A IE2000/0821 A IE 2000/0821A IE 20000821 A IE20000821 A IE 20000821A IE 83848 B1 IE83848 B1 IE 83848B1
- Authority
- IE
- Ireland
- Prior art keywords
- module
- zooplankton
- fish
- water
- aquaculture system
- Prior art date
Links
- 238000009360 aquaculture Methods 0.000 title claims description 37
- 244000144974 aquaculture Species 0.000 title claims description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 68
- 241000251468 Actinopterygii Species 0.000 claims description 65
- 241000195493 Cryptophyta Species 0.000 claims description 35
- 238000004519 manufacturing process Methods 0.000 claims description 23
- 230000000384 rearing Effects 0.000 claims description 23
- 235000013305 food Nutrition 0.000 claims description 22
- 239000002028 Biomass Substances 0.000 claims description 16
- 239000002699 waste material Substances 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 10
- 235000019749 Dry matter Nutrition 0.000 claims description 8
- 239000008213 purified water Substances 0.000 claims description 5
- 239000006227 byproduct Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 description 19
- 241000196324 Embryophyta Species 0.000 description 16
- 229910052760 oxygen Inorganic materials 0.000 description 14
- 239000001301 oxygen Substances 0.000 description 14
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 14
- 235000021317 phosphate Nutrition 0.000 description 10
- 239000004033 plastic Substances 0.000 description 9
- 229920003023 plastic Polymers 0.000 description 9
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 241001532704 Azolla Species 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 150000002823 nitrates Chemical class 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 238000007540 photo-reduction reaction Methods 0.000 description 6
- 238000009372 pisciculture Methods 0.000 description 6
- 239000010865 sewage Substances 0.000 description 6
- 241001302187 Moina Species 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- -1 hydrogen ions Chemical class 0.000 description 4
- 230000029553 photosynthesis Effects 0.000 description 4
- 238000010672 photosynthesis Methods 0.000 description 4
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 4
- 241000238578 Daphnia Species 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000001717 pathogenic Effects 0.000 description 3
- 244000052769 pathogens Species 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 241000894006 Bacteria Species 0.000 description 2
- 241001494246 Daphnia magna Species 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K [O-]P([O-])([O-])=O Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 235000005911 diet Nutrition 0.000 description 2
- 230000037213 diet Effects 0.000 description 2
- 238000003306 harvesting Methods 0.000 description 2
- 230000001965 increased Effects 0.000 description 2
- 230000002503 metabolic Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 235000015097 nutrients Nutrition 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000003134 recirculating Effects 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 241000238426 Anostraca Species 0.000 description 1
- 241000271566 Aves Species 0.000 description 1
- 210000000481 Breast Anatomy 0.000 description 1
- 241000195649 Chlorella <Chlorellales> Species 0.000 description 1
- 241000252233 Cyprinus carpio Species 0.000 description 1
- 241000238557 Decapoda Species 0.000 description 1
- 240000003826 Eichhornia crassipes Species 0.000 description 1
- 241001417103 Gyrinocheilidae Species 0.000 description 1
- 240000008415 Lactuca sativa Species 0.000 description 1
- 235000003228 Lactuca sativa Nutrition 0.000 description 1
- 241000595940 Notostraca Species 0.000 description 1
- 229940082615 Organic nitrates used in cardiac disease Drugs 0.000 description 1
- 240000004808 Saccharomyces cerevisiae Species 0.000 description 1
- 241000195663 Scenedesmus Species 0.000 description 1
- 241001291279 Solanum galapagense Species 0.000 description 1
- 241001520689 Tanichthys albonubes Species 0.000 description 1
- 241000306033 Thamnocephalus platyurus Species 0.000 description 1
- 241000276707 Tilapia Species 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H Tricalcium phosphate Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000031018 biological processes and functions Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 235000011010 calcium phosphates Nutrition 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 230000004059 degradation Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 235000015872 dietary supplement Nutrition 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000009348 integrated aquaculture Methods 0.000 description 1
- 230000001665 lethal Effects 0.000 description 1
- 231100000518 lethal Toxicity 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 150000002826 nitrites Chemical class 0.000 description 1
- 235000020912 omnivore Nutrition 0.000 description 1
- 244000054334 omnivore Species 0.000 description 1
- 239000010815 organic waste Substances 0.000 description 1
- 238000006213 oxygenation reaction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 244000062645 predators Species 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 230000001850 reproductive Effects 0.000 description 1
- 230000000717 retained Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 235000015170 shellfish Nutrition 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing Effects 0.000 description 1
- 230000002588 toxic Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 241001148471 unidentified anaerobic bacterium Species 0.000 description 1
Description
Introduction
The invention relates to fish farming systems and effluent, waste or water treatment
systems which are generically referred to as aquaculture systems in this specification.
Conventional fish farm production systems are of two main types, namely a pond
based system or a cage/raceway production system.
In pond production fish are stocked in growing ponds. Three regimes exist:
(a) Fish are left to survive on the plant and animal life of the pond (typical
yield 200kg/hectare)
(b) The ponds are fertilised (typical yield l-2 ton/hectare)
(c) Ponds are fertilised and the fish are also fed high grade food (yield 3-10 ton
/hectare)
This type of fish farming is a batch process. Eventually the pond water becomes
unsuitable for fish production and has to be replaced, either naturally (rain, etc) or by
mechanical means. Generally the best yields achievable are 1 kg of fish per ton of
water.
In cage fish farming, fish are held in cages floating in a large body of water (lake or
sea) and the fish are fed complete diets. Fish waste drops through the meshes of the
cages. This technique relies on the large body of water to dilute the water in the cages
and so maintain suitable growing conditions. Yields based on cage area can be quite
large, 100 tons per hectare. However, based on total water requirements yields are
only of the order of one ton per hectare.
In raceway systems fish are housed in raceways and are fed complete diets. Fresh
water is continuously passed through the raceway to remove waste and to maintain
suitable growing conditions. Yields based on the area of raceway, can be up to 400
tons per hectare, however, based on water requirements (60 cubic meters of water per
hour, per ton of fish) yields are of the order of 1 ton of fish per 0.5 million cubic
meters of water.
In some raceway systems, wastewater is treated and recirculated. Treatment involves
passing the water through aerobic digesters (sometimes called “active filters”) and
reoxygenation. This treatment is sufficient to reduce ammonia and nitrites to less
toxic nitrates, but eventually the water becomes unsuitable for fish growing and has to
be replaced. Biomass also builds up in the aerobic digesters. In the last few years
there has been an increasing interest in using plants as a means of water treatment (the
new fields of aquaponics). In this technique, the plants, e.g. tomatoes, lettuce, etc are
grown hydroponically with wastewater from the fish being used as the hydroponic
solution. The treated water from the hydroponic bed is then recycled to the fish
containers. Some of the hydroponic plants are also used as a food supplement for the
fish. Aquaponics is still an infant science and is not widely applied.
This invention is directed towards providing an aquaculture system which will
overcome at least some of the problems with conventional systems.
Statements of Invention
According to the invention there is provided an aquaculture system comprising:
an aerobic digester for digesting waste and producing biomass;
a primary algae treatment section for treating the biomass from the aerobic
digester;
a zooplankton module for consuming the algae treated biomass and generating
zooplankton and water;
an algae module for treating the water from the zooplankton module; and
a dry matter content consuming section for consuming at least some of the
zooplankton harvested from the zooplankton module.
Preferably the aerobic digester and primary algae treatment section are provided in the
same module.
In one embodiment the dry matter content consuming section is a fish rearing module.
In this case preferably waste generated in the fish rearing module is digested in the
aerobic digester.
In another aspect the invention provides an aquaculture system comprising:—
a fish rearing module;
a digester module for treating by-products from the fish rearing module;
a zooplankton module for consuming biomass produced by the digester, the
zooplankton module producing zooplankton and water; and
an algae production module.
The zooplankton module may produce carnivorous zooplankton.
Preferably the aquaculture system includes:-
a herbivorous zooplankton module for consuming algae produced in the algae
production unit; and
a higher order plant module for consuming waste produced by the herbivorous
zooplankton module.
Carnivorous zooplankton from the carnivorous zooplankton module preferably
provide food which is fed to the fish in the fish rearing module.
Herbivorous zooplankton from the herbivorous zooplankton module preferably
provide food which is fed to fish in the fish rearing module.
Higher order plants produced in the higher order plant module preferably provide food
which is fed to fish in the fish rearing module.
Purified water produced in the higher order plant module preferably provides a water
supply to the fish rearing module.
In a particularly preferred embodiment at least some of the modules are defined by an
elongate tube of flexible translucent material, the tube extending longitudinally along
a tube site and having a lower section defining a water course.
Brief Description ofthe Drawings
The invention will be more clearly understood form the following description thereof
given by way of example only with reference to the accompanying drawings, in
which: -
Fig. 1 is a diagrammatic perspective view of an aquaculture apparatus
according to the invention;
Fig. 2 is a transverse cross sectional view of the aquaculture apparatus of Fig.
Fig. 3 is a longitudinal cross sectional view of the aquaculture apparatus of
Fig. 1;
Fig. 4 is a perspective view of the aquaculture apparatus being assembled;
Fig. 5 is a diagrammatic end view of another aquaculture apparatus according
to the invention;
Fig. 6 is a longitudinal cross sectional View of part of the apparatus of Fig. 5;
Fig. 7 is a plan view of one end of the apparatus of Fig. 6;
Fig. 8 is a diagrammatic perspective View of an aquaculture apparatus
according to another embodiment of the invention;
Fig. 9 is a transverse cross sectional view of the apparatus of Fig. 8;
Fig. 10 is a transverse cross sectional view of the apparatus of Fig. 8 on an
enlarged scale;
Fig. 11 is a perspective view of the apparatus of Figs. 8 to 10 being assembled;
Fig. 12 is a transverse cross sectional view of a further aquaculture apparatus
of the invention;
Fig. 13 is a cross sectional view of an enlarged scale of part of the apparatus of
Fig. 12;
Fig. 14 is a cross sectional view of part of yet another aquaculture apparatus of
the invention;
Fig. 15 is a block diagram of an aquaculture system according to the invention;
Fig. l5(b) is a diagram illustrating the jointing of a module interconnecting
pipe to a plastics tube module;
Fig. 16 is a graph of typical oxygen concentration through each module of the
system of Fig. 15;
Fig. 17 is a block diagram of another aquaculture system according to the
invention with negative feedback loops;
Fig. 18 is a block diagram of another aquaculture system of the invention; and
Fig. 19 is a block diagram ofa further aquaculture system of the invention.
Detailed Description
Referring to the drawings there is illustrated an aquaculture apparatus comprising an
elongate collapsible tube 2 of flexible translucent plastics material. The tube 2 is
inflatable to be air supported in the expanded in use configuration illustrated for
example in Figs. 1 to 3.
The tube is formed from a plastics material such as that available from Autobar
Plastics of France under the trade name ldalene Ceva 4S. The diameter of the
expanded tube 2 is at least 600mm and may be up to 6m or greater. The tubes 2 are
mounted on a reel and may be cut to any desired length, typically 100 metres or
longer.
The tube 2 may be inflated either by a suitable fan and/or by using a wind directing
system in the form of a venturi at one end of the tube 2. The other end of the tube 2 is
closed off to prevent air escape. A fan may be used to maintain air support, especially
where an access way is provided.
In use, water is pumped into each tube, typically to a level L corresponding to a
desired depth of about 300 to 1000 mm.
Referring in particular to Figs. 1 to 4 in this case there are two tubes 2 which are
arranged to extend longitudinally side by side along a suitable site with level ground
as illustrated in Fig. 4. Each tube 2 is then inflated and is maintained supported by air.
The adjacent tubes 2 are covered by an outer layer of translucent insulating film
material. The outer layer 17 may be of the same material as that of the tubes 2. The
outer layer 17 provides an air gap 19 which insulates the inner tube 2 to restrict heat
loss. In addition, the outer layer 17 assists in protecting the tubes from ingress by
predators such as birds.
The cover 17 may be translucent, or in particularly hot climates may be of opaque
material for shading. It may be pulled relatively tight over the tubes, or preferably
may itself be at least partially air supported.
Air may be delivered by a fan through an inlet at one closed end of one tube 2 and led
from one tube 2 to an adjacent tube. In the case of an air supported cover, at an end of
the second tube some air may be bled into the space between the tubes 2 and the cover
to support the cover.
Retaining means in the form of mounds 18 of clay are applied over the side edges of
the outer layer 17. The outer layer 17 is closed as both ends and mounds 18 are also
applied at the end edges of the outer layer 17. The mounds 18 not only assist in
retaining the layer 17 in position but also act as a wall to retain water, if necessary, for
example on deflation of the tubes.
Referring to Figs. 5 to 7 the arrangement is similar to that of Figs. 1 to 4 except that in
this case the apparatus includes an accessway. The accessway comprises two spaced-
apart doors 40, 41 which form an air lock 42 therebetween. The doors 40, 41 are
mounted in frames which are sealed to the tubes 2 and/or the cover 17. In this case a
cover is omitted in Fig. 6.
In the arrangement illustrated in Figs. 8 to 11 the tubes 2 are arranged to extend
longitudinally side by side to form at least some modules of an integrated aquaculture
system. In this case a track 5 is dug in the ground on a suitable, typically flat, site. A
mound 10 is built up on one side of the elongate track 5 and a first tube 2 is laid down.
The tubes are then inflated and are air supported. The exposed longitudinal edge of
the first tube 2 may be supported by a smaller elongate mound ll. Adjacent tubes 2
are arranged in a similar way until the last tube 2 in the system is laid and supported
by a second main mound 11. Between the main mounds 10, II the tubes effectively
support one another.
Additional retaining mounds 15 may be provided between
adjacent tubes 2.
A water system may be provided for directing water from one tube 2 to another. A
suitable weir, lock system and/or pumping may be used for this purpose.
Referring to Fig. 12 there is illustrated another aquaculture apparatus 16 which is
similar to that described above with reference to Figs. 1 to 4 and like parts are
assigned the same reference numerals. In this case the additional retaining mounds 15
are larger so that each tube 2 is separately supported. In this case and as illustrated in
Fig. 13 some or all of the tubes 2 may be covered by an outer layer 17 of translucent
insulating film material which is retained on either side of the tube 2 by retaining
mounds 18. The outer layer 17 provides an air gap 19 which insulates the inner tube 2
to restrict heat loss.
Referring to Fig. 14 there is illustrated a single tube of another aquaculture apparatus
of the invention. In this case an intermediate support mound 50 is provided which
divides the lower part of the tube 2 into a pair of tube parts which are separated by an
elongate section 51 which may be used to provide an access walkway above the level
L of the water in the tube parts.
Referring to Fig. 15 there is illustrated an aquaculture system which may be used for
rearing fish or for effluent/waste treatment. A first module A is a dry matter content
consuming module which may, for example, be a fish rearing module. A second
module B is an aerobic digester for digesting waste which may be delivered directly
into the module B and/or may be waste generated in the fish rearing module A. The
module B also includes a primary algae treatment section for treating the biomass
generated by the aerobic digester. The aerobic digester and primary algae treatment
are preferably provided in a single module B for ease of construction and control in
use. A third module C is a zooplankton module for consuming the algae treated
biomass. Zooplankton generated in module C is fed to the dry matter consuming
module A. Waste from the zooplankton module is delivered into an algae treatment
module D in which the water is purified by a tertiary treatment using algae. The
purified water generated in the algae treatment module D is either used as a water
supply for module A when it is a fish rearing module and/or the water may be drawn
off for re-use or discharge. The flow of water through the system and the direction of
feedback control loops are indicated in Fig. 15 by arrows X and Y respectively.
Fig. l5(a) illustrates the jointing of a module interconnecting pipe 70 to a plastics tube
2 forming one of the modules. The pipe 70 is inserted into a hole in the tube 2 and the
hole is sealed by a jointing means 71 in the form, for example of a deformable rubber
seal and a jubilee clip to grip the tube to the seal.
The four module unit is the minimum configuration in the sense that is necessary to
separate physically the different process that takes place. This could in principle be
carried out in one long tube but the process would be difficult since it involves using
the water from each module at different rates.
Figure 16 shows how oxygen levels change through each module. Similar changes
also occur in the pH, ammonia, nitrate, sulphate and phosphate levels. In this case
each of the modules is 30 m long and the graph shows how the oxygen level oscillates
through the modules. The pH level in general tracks the oxygen level and this
oscillation has the effect of killing off most pathogens. By adjustment of various
parameters the system can be tuned using feedback control.
These cycles in the oxygen levels, pH, etc, are important to the operation of the
system. If the pH of the water entering the algae module D is greater than 7.5 then on
a sunny day > 2.5kwh/day m then the pH can rise above 10 which is lethal to fish. It
is therefore necessary to keep the pH below 7.5 in fish production (but not in sewage
treatment) by passing water of 7.5 pH through a module containing higher order plants
(e.g. azolla or water hyacinth), the pH is reduced to 6.5.
Referring to Figure 17 there is illustrated a schematic diagram of a four module
system similar to Fig. 15 in which water flow is indicated by arrows X and negative
feedback loops are indicated by arrows Y. The system has the following negative
feedback loops.
(i) module D to module C
(ii) module C to module B
(iii) module D to module B
(iv) module C to module A
The key to how the system works is to balance the two biological processes described
by the following two equations.
) biomass + oxygen = carbon dioxide + water + nitrates + phosphates + sulfates +
hydrogen ions.
This is the oxidization process.
) carbon dioxide + water + nitrates + phosphates + sulfates + hydrogen ions +
sunlight = biomass + oxygen
This is the photo reduction process.
In most sewage and water recirculating systems attention is mostly given to the
oxidation process. Water is biologically oxidised in aerobic digesters (anaerobic
conditions are not discussed here). Oxygen is supplied to the system and the nitrates,
phosphates, sulfates and hydrogen ions are then treated separately.
_11_
In this system the oxidation and photo reduction processes are given equal
consideration.
If the photo reduction process is allowed to dominate then the pH of the system will
increase and the system will crash. If the oxidation process is allowed to dominate the
system will become anaerobic, the pH will drop and the system will crash.
In order to prevent either of these situations arising and to keep into account the
variations in sunlight and temperature (the main random variables in this system), the
system is fitted with the four negative feedback loops labelled (i) to (iv) in the
schematic diagram.
The relative sizes of the different modules is designed to suit the local conditions and
the production levels. Unlike the existing recirculating processes based mainly on the
oxidation process there is a minimum level of consumers (fish, zooplankton, etc.) that
must be produced to counteract the photo reduction process. Photosynthesis rates of
% of incident light have been archived with this system but 3% is more typical.
Feedback loop (i) is used to decrease the photo reduction process and increase
zooplankton levels.
Feedback loop (ii) is used to alter the oxidation process with minimum effect on photo
reduction.
Feedback loop (iii) is used to increase oxygen levels in module 2 to prevent it
becoming anaerobic.
Loop (iv) is used to lower the zooplankton level and increase the fish biomass.
In sewage treatment allowing the algae in module D to increase in density allows the
pH to rise to 10.5. Above pH 8.4 the phosphates precipitate out. Each one unit
increase in pH gives a tenfold increase in the amount of precipitation of phosphates.
Thus, purified water which is high in oxygen but low in phosphates can be discharged.
Sewage treatment involves taking used water with a high organic component and
biological oxygen demand (BOD) and treating it to reduce the suspended organic load
and BOD to 30 and 20 p.p.m. respectively.
Organic waste + treatment + oxygen = 1) Synthesis i.e. increased sludge which is
removed.
2) Degradation and hydrolysis which gives
nitrates phosphates sulphates carbon dioxide
water and hydrogen ions.
There are three main treatments:
(a) anaerobic
(b) aerobic
(c) photo—autotrophs
It is possible to use gas supported plastic tubes in all three treatment processes.
The use of air supported plastic tubing in sewage treatment depends on the climate.
In temperature climates the higher temperatures that are attained in the tubes allow the
rate of photosynthesis to increase. Photosynthesis increases the rate of oxygenation of
the system and thus destroys anaerobic bacteria.
Photosynthesis also increases the pH. It is not unusual to have the pH rise from pH to
7.5 to pH of 9 or 10. Above a pH of 8.1 up to 80% of phosphates are precipitated as
calcium phosphate. For every unit increase in pH, the amount of phosphate in the
final effluent is deceased by a factor of 10. Also as the pH within the tubing increases
most algae and other organisms are killed and precipitate out.
In Very warm climates the temperature of the water in the air supported polytubes can
easily rise above 50°C and pasteurise the water. At high temperatures thermophilic
organisms also break down organic nitrates. So depending on the climate, the air
supported polytubes can be used for water purification.
In situations where the BOD requirements of effluent is high the oxygen in the air
supported polytubing can be used up and the tubing can become anaerobic. This
situation is equivalent to the grease build up in anaerobic ponds, however the sealing
nature of the plastic stops the spread of odours which is the main problem with this
system of system. Also the plastic can be used to trap the methane and other
combustible gases which are released in anaerobic process and these gases are then
available for use.
Referring to Fig. 18 an aquaculture system of the invention comprises a number of
production modules as follows:
(a) Fish production in a main pond 20
(b) Algae production in a second pond 21
(c) Aerobic digesters in a third pond 22
(d) Carnivorous zooplankton (e.g. moina) for fish food in a fourth pond 23
(e) Algae (as food for herbivorous zooplankton)
(f) Herbivorous and omnivorous zooplankton e.g. daphnia, fair shrimp in a
fifth pond 26.
(g) Higher order aquatic plants for fish food (e.g. azolla) in a sixth pond 25
The important features of the process are that the product in each module is harvested
on a continuous basis, the level of production in each module is adjusted to suit its
interconnecting modules, and the water is monitored and adjusted to suit each
production module.
With appropriate nutrients, the overall limit on production is the level of sunlight
received by the algae and plants. The overall production fixes between 1.6 to 2.3% of
the sunlight obtained by the algae and plants and is approximately 1 kg of fish per
square metre, per year.
The efficiency of the system is therefore dependent on the temperature and growing
conditions provided by the flexible tubing 2. The production capacity of each module
should be matched to its interconnecting module(s).
(l) The digester 22 denatures the metabolic by-products from fish production and
various fish pathogens.
(2) The biomass (bacteria, yeasts, etc) produced by the digester 22 is consumed by
the carnivorous zooplankton (e.g. moina) 23 which are in turn fed to the fish
.
(3) The water from the moina is used in algae production 21.
(4) The build-up of minerals such as Ca, P and K and nitrates etc in the fishpond
is prevented by passing the water from the fishpond to the algae module 21.
(5) The algae 21 is then used as food for the herbivorous zooplankton 26 such as
daphnia, fairy shrimp, shellfish, etc. which can also be used as fish food.
(6) The waste products from the herbivorous zooplankton are used by the higher
order aquatic plants 25 and the purified water is returned to the fish rearing
module 20. The azolla and other plants are also used as fish food.
The following is a list of the main fish food crops produced within the system:
(1) Algae such as Chlorella, Scenedesmus, etc.
(2) Daphnia magna, an algae eater. The reproductive cycle of Daphnia magna at
elevated temperatures is less than 10 days and this allows for 10% harvest per
day.
(3) Moina dubia lives on bacteria produced in the aerobic digester.
(4) Tanymastic stagnalis used in spring and autumn when temperatures are less
than 20C, is an omnivore and grows to l.5cm in size.
(5) Thamnocephalus platyurus only grows when temperature >20C, grows to 2
ems.
(6) Azolla: a high protein plant for herbivorous fish. Our experiments show that
approximately 1/3 of the dry matter content is converted into fish biomass.
Under favourable conditions we have found that azolla can double its weight in
to 10 days allowing for a 10% harvest per day.
Actively feeding Daphnia and Moina are a good food source for fish up to 5 grrns in
weight. For larger fish the effort involved in catching these small organisms reduces
the over all conversion rate. For larger fish the fairy shrimps are the best source of
food. White cloud mountain minnow are also a good food source for larger
carnivorous fish.
Referring to Figure l9 there is illustrated an example of a six module system similar to
Fig. 18. In this case the modules comprise a fish raceway 50, an aerobic digester and
algae pond 51, a zooplankton module 52, a higher order plants (azolla etc.) module 53,
an algae module 54 and a heat exchanger 55. The arrows indicate the direction of
water flow. Modules 50, 51, 52 and 54 are equivalent to modules A to D respectively
described above with reference to Fig. 15. The heat exchanger module 55 is used to
stabilise the water temperature, especially when the water is to be used in the fish
rearing module.
The outer box around the module pairs 51, 54 and 52, 53 indicates an optional cover
over two tubes ~ similar to the arrangement of Figs. 1 to 4.
The aquaculture system of the invention has several advantages over conventional
systems. These include the following.
(1) Because they are closed systems they have no polluting discharges.
(2) They can be filled with rainwater and as such are not limited to being located
near rivers or the sea.
(3) The elevated temperatures allow for the rapid production of food organisms
within the system. This is a major economic advantage of polytunnels.
(4) The range of products is much greater.
Higher food conversion ratios are achieved. In normal intensive fish farming 1.5-
l.6kg of food (dry weight) is needed to produce 1 kg of fish (wet weight). This means
that up to 80% of the dry matter is wasted and discharged from the system. These
excess nutrients cause eutrophication of the local water systems with uncontrolled
algae blooms. Within the aquaculture system of the invention algae growth is
controlled and is fed to zooplankton which are in turn fed back to the fish. Thus 1 kg
(dry weight) of food will give a much higher food conversion rate than conventional
processes.
There is no pollution of local water systems. Most recycled water systems are based
on biological filter beds that have to be back flushed and have discharges to either a
sewage system or directly to the environment. This is wasteful of resources and puts a
strain on the enviromnent. Sunlight has a direct effect on reduction of pathogens.
Most “recycled” systems have a build up of metabolics over time. Because of this
they are not complete recycled systems.
Specialisation of sites is not necessary. Present fish farming is restricted to particular
locations, i.e. rivers, lakes, fjords or areas with high water tables / low permeable soils.
This system allows fish farming to be carried out anywhere where there is sufficient
level ground. Once the tubes are filled with water evaporational losses are very low.
(In experimental systems, evaporation of water has been less than 50 per annum). The
system is suitable for both fresh water and sea water use.
Production cycles are significantly shorter. The higher temperature in the tunnels
allows for shorter production cycles ( for carp and tilapia, typically 150 days)
It will be appreciated that the apparatus ofthe invention may be utilised as elements in
an integrated system for rearing fish, aquatic materials effluent treatment, waste
treatment, water treatment and the like. The apparatus may also be used as an
individual element to enhance the performance of existing non—integrated systems.
_17-
A gas other than air may be used to support the tube. For example, oxygen may be
used in some instances. In other cases other gases such as methane may be available
for use as at least portion of the gas support.
The invention is not limited to the embodiments hcreinbefore described which may be
varied in detail.
Claims (1)
- Claims An aquaculture system comprising: an aerobic digester for digesting waste and producing biomass; a primary algae treatment section for treating the biomass from the aerobic digester; a zooplankton module for consuming the algae treated biomass and generating zooplankton and water; an algae module for treating the water from the zooplankton module; and a dry matter consuming section for consuming at least some of the zooplankton harvested from the zooplankton module. An aquaculture system as claimed in claim 1 wherein the aerobic digester and primary algae treatment section are provided in the same module. An aquaculture system as claimed in claims 1 or 2 wherein the dry matter consuming section is a fish rearing module. An aquaculture system as claimed in claim 3 wherein waste generated in the fish rearing module is digested in the aerobic digester. An aquaculture system as claimed in any of claims 1 to 4 wherein at least some of the modules comprise an elongate tube of flexible translucent material, the tube extending longitudinally along a tube site and having a lower section defining a water course. An aquaculture system comprising:- a fish rearing module; a digester module for treating by-products from the fish rearing module; a zooplankton module for consuming biomass produced by the digester, the zooplankton module producing zooplankton and water; and an algae production module. A system as claimed in claim 6 wherein the zooplankton module produces carnivorous zooplankton. An aquaculture system as claimed in claim 6 or 7 including:— a herbivorous zooplankton module for consuming algae produced in the algae production unit; and a higher order plant module for consuming waste produced by the herbivorous zooplankton module. An aquaculture system as claimed in claim 7 or 8 wherein carnivorous zooplankton from the carnivorous zooplankton module provide food which is fed to the fish in the fish rearing module. An aquaculture system as claimed in claim 8 or 9 wherein herbivorous zooplankton from the herbivorous zooplankton module provide food which is fed to fish in the fish rearing module. An aquaculture system as claimed in any of claims 7 to 10 wherein higher order plants produced in the higher order plant module provide food which is fed to fish in the fish rearing module. An aquaculture system as claimed in any of claims 7 to 11 wherein purified water produced in the higher order plant module provides a water supply to the fish rearing module. An aquaculture system as claimed in any of claims 7 to 12 wherein at least some of the modules are defined by an elongate tube of flexible translucent material, the tube extending longitudinally along a tube site and having a lower section defining a water course. Apparatus substantially as hereinbefore described with reference to the accompanying drawings. A system substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IE2000/0821A IE83848B1 (en) | 2000-10-11 | Aquaculture |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IEIRELAND11/10/19991999/0838 | |||
IE990838 | 1999-10-11 | ||
IE990839 | 1999-10-11 | ||
IE2000/0821A IE83848B1 (en) | 2000-10-11 | Aquaculture |
Publications (2)
Publication Number | Publication Date |
---|---|
IE20000821A1 IE20000821A1 (en) | 2001-04-18 |
IE83848B1 true IE83848B1 (en) | 2005-04-06 |
Family
ID=
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6827036B2 (en) | Aquaculture | |
CN101902904B (en) | Aquaponics facility for producing vegetables and fish | |
US4169050A (en) | Buoyant contact surfaces in waste treatment pond | |
CN105859049B (en) | A kind of biogas slurry Ecological Disposal cultivating system and its operational method | |
EP3462852B1 (en) | Aquaponic unit | |
CN102674558A (en) | Integrated type ecological floating bed and water body ecological system repairing technology thereof | |
CN103250668A (en) | System combining aquaculture and soilless agriculture planting | |
JP2008061570A (en) | Vegetable with low nitrate nitrogen, and method and system for cultivating the same | |
CN111248128B (en) | External circulation freshwater shrimp breeding method | |
CN105859051A (en) | Biogas slurry optical treatment breeding system and working method thereof | |
CN109892232A (en) | Aggregate species cultivating system and its application in scale animal and poultry cultivation treatment for cow manure | |
KR20170029280A (en) | the rearing system using the food chain structure | |
KR20220036920A (en) | Ecological circulation agriculture and livestock integrated production system. | |
CN206559930U (en) | A kind of box breeding consubstantiality ecologic breeding floating bed | |
IE83848B1 (en) | Aquaculture | |
CN213881396U (en) | Annual large-scale aquaculture system for snail and shellfish aquatic products | |
IE20000821A1 (en) | Aquaculture | |
CN212436793U (en) | Soilless culture fish-vegetable symbiosis treatment system | |
CN208732878U (en) | A kind of landscape type domestic sewage ecologically treating system | |
CN102398991A (en) | Undercurrent type garden filter tank sewage treatment system | |
KR101923803B1 (en) | Energy-saving biofloc culture system using solar energy | |
Pierce | Water reuse aquaculture systems in two solar greenhouses in Northern Vermont | |
CN212034977U (en) | Fish and vegetable symbiotic system in marine environment | |
Busch et al. | Water movement for water quality in catfish production | |
Jingsong et al. | The function of ecological engineering in environmental conservation with some case studies from China |