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RECIRCULATORY AQUACULTURE SYSTEM

RECIRCULATORY AQUACULTURE SYSTEM

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Recirculating Aquaculture Systems

RECIRCULATORY AQUACULTURE SYSTEM

PrabashlalRadhakrishnanAnjusha b

Group members.2

Aquaculture is one of the fastest growing sectors of food production in the world.

To meet the increasing global demand for protein source and to overcome the dependence on capture fisheries resource AQUACULTURE is the best alternative.

Introduction

As we know .3

World production 2008 -2.8 million tonnes 2010 -3.7 million tonnes (FAO, 2009; FAO GLOBEFISH, 2011a) 2015 -4.6 million tonnes and 5 million tonnes (FAO, 2010). Global demand for fish increasing @ 3.2% per year World per capita fish supply increased from 9.9 kg in the 1960s to 18.6 kg in 2010.

Cultured species such as tilapia, catfish, salmon, trout, oysters and clams are high in demand and the profit level is very high.In 2008, commercial aquaculture production was about 2.8 million tonnes. The production was forecasted to reach 3.7 million tonnes by the end of 2010 (FAO, 2009; FAO GLOBEFISH, 2011a). By 2015, world production is expected to reach between 4.6 million tonnes and 5 million tonnes (FAO, 2010). According to the FAOs The State of World Fisheries and Aquaculture 2012, global demand for fish has increased 3.2% year over year. World per capita fish supply increased from 9.9 kg in the 1960s to 18.6 kg in 2010

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Closed systemUsed for freshwater speciesrequires maintenance of water quality parameters.land-based rearing of aquatic species in raceways tanks and pondsRecirculation technology is implemented which cycles water through filtration processes and returns it back into the aquaculture system.

Open systemprimarily used for marine water speciesWater quality parameter is not maintained in this system.rearing on aquatic species in Sticks, ropes, racks and cages.Recirculatory technology is not implemented.

TYPE OF AQUACULTURE SYSTEM

Now there are 2 types of AC systems they are.. Closed and open

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DefinitionRecirculating aquaculture encompasses systemsused for the rearing of aquatic organisms where90 % or more of system water is recycled.

Now the definition of RAS is given as

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Why Recirculating Aquaculture?Scarcity of good quality water for aquaculture.

Land is expensive, especially near good areas with plenty of water.

Greater control over effluents and treatment.

Permits the culture of aquatic organisms outsideof natural range.

Now why would we need such a system in aquaculture? It is because it has a number of benefits which we cant turn away from, ..like:7

continuedIt is practiced with limited source of waterRequire minimum areaMultiple use of waste materials like water and fertilizer.Threat to pollution is minimised land and water is conserved

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Background1950s First RAS started in japan 1970s started experimentally in Europe 1980s Commercial utilisation started in northern Europe, especially in the Netherlands, Denmark and Germany

RAS was first developed in Japan in 1950s , then Europe started experimenting with it and got success and modified it further for commercial usage by 1980;s commercial utilization kicked off in northern Europe specially in the countries like Denmark and Germany.9

Principle of Recirculatory systemsA recirculation system is a closed system. It involves fish tanks, filtration and water treatment systems. The fish are housed in tanks and the water is exchanged continuously which guarantees optimum growing conditions.

Water is pumped into the tanks, through biological and mechanical filtration systems and then returned into the tanks.There is no complete water exchange, rather only 5% to 10% water exchange rate per day is being done, depending on stocking and feeding rates.

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Recirculation ComponentsSite ComponentsBuildingPump HouseThree Phase ElectricityEmergency GeneratorBulk Feed StoragePurging and Packaging Facilities

Site Components: The site components include equipment and structures that are not part of the actual recirculation system.Building: An insulated building or shed is required to protect the recirculation system from external climatic conditions. Pump House: Its purpose is to provide protection for the pump ensuring that it does not come into contact with moisture created from humidity or outside environmental conditions that could potentially damage the pump.Three Phase Electricity: the high energy consumption requirements from the system. Emergency Generator : An emergency generator is required just in case mains power is disconnected due to faults, overloading or maintenance. Fish can only survive for very short periods without oxygen or filtration.Bulk Feed Storage: As large amounts of food are required to feed large numbers of fish, a storage facility is required to protect food from vermin as well as mildew and mould caused by moisture.Purging and Packaging Facilities: Fish will need to be purged to expel waste matter before they are sent to markets. Fish will need to be processed and packaged if they are not sold to the live market therefore a suitable processing facility that reaches quality control standards will need to be incorporated into the facility.11

Fine & DissolvedSolids RemovalSolidsCaptureWaste Mgmt

Biofiltration& Nitrification

Hydraulics

CO2 Removal

Aeration & Oxygenation

Disinfection & SterilizationSystem Components

SystemControl

System components In the tank the solid waste which are been accumulated constantly are been taken up by hydraulic pump.. which is then passed through mechanical filter unit where the large suspended mater are being trapped and removed. Then hydraulic pump which sends them to the bio filtration unit.Here. the breakdown of the large bio macromolecules takes place. It has nitrifying bacterias which breaks down the nitrogen components( ammonia) into simpler forms. Aeration which is being provided brings in the supply of oxygen, hence restroing the balance of the dissolved gasses to the optimum levels, in the unit. The sterilization and disinfection unit furthers removes the harmful pathogens which may be present in the system .Thus all the system components work together in keeping the system in a dynamic equilibrium and providing the optimum ranges of intrinsic parameters in the unit. 12

System ComponentsSource of AerationFish require optimum levels of oxygen to survive.Oxygen can be added to the system via an oxygen generator, to maintain suitable oxygen levels at high stocking rates.Aeration pumps will provide the tanks with both oxygen and water circulation.

Tanks5,000 to 10,000 liters are most commonly used. Non corrosive therefore plastic or fiberglass is recommended.Smooth round tanks with a conical shaped bottom draining.Pumps and PipesPumps and pipes are required to move water around the system

TanksProduction tanks will vary in size and shape however round tanks between 5,000 to 10,000 liters are most commonly used. Tanks need to be non corrosive therefore plastic or fiberglass is recommended. Smooth round tanks with a conical shaped bottom are considered advantageous as this will assist with waste solids disposal during draining.Pumps and PipesPumps and pipes are required to move water around the system. It is important to ensure that both pumps and pipes are the correct size to allow adequate flow rates through the tanks and other system components.

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In a dual drain reciculatory system,

in that a vortex currnt is being formed, the tank in the center has a small outlet drain.

The vortex created by the water, carries with it all the solid wastes and accumulates them to the centre.

From the center the wastes are being taken out along with a small fraction of water, say about -5-20% and most of the water is recirculated back through the overflow drainage system located at the top side.15

Mechanical FiltrationRemoves suspended solids

Pipes and equipment components do not become clogged with waste material.

Decomposing waste matter left in the fish tanks will consume available oxygen within the water column.

Some types include drum filtration, screen filtration, foam fractionation, settlement tanks, sand filters.

regular back-flushing to prevent the accumulation of sludge.

Mechanical filtration removes suspended solids obtained from faeces and un-eaten feed.

Removal of solids is important to ensure that pipes and equipment components do not become clogged with waste material.

Decomposing waste matter left in the fish tanks will consume available oxygen within the water column.

Some types include drum filtration, screen filtration, foam fractionation, settlement tanks, sand filters.

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A vertical moving screen consists of a rotating screen which is made up of metal chains, the solid particles adheres to the surface of the chain and is carried up due to the rotation, a spray of water washes the screen on the top and the wastes are carried out through a window.17

In a foam fractionator, there consists of 2 tubes, one large and one small, the large chamber has air supply which creates air bubbles, the colloids are trapped onto these bubble and are taken up, where a funnel is present , when the bubble breaks the colloids are released to the air and thus taken out of the system.18

In rotating drum type, it consists of a rotating drum screen which is open in one end. The dirty water enters the drum and the solid particles are trapped inside the screen of the drum, a backwash system washes the screen and takes away the dirt from the drum out of the system.19

Biological FiltrationFish produce ammonia and nitrites as metabolic waste products which are toxic.

Bio-filters consist of a medium with a large surface area upon which nitrifying bacteria will colonize after a few weeks.

These bacteria will convert toxic ammonia and nitrites into non-toxic nitrates via oxidation. This process is known as nitrification.

It will usually take a few weeks to a month before nitrifying bacteria colonize and the bio-filter becomes active.

Fish produce ammonia and nitrites as metabolic waste products which are highly toxic. These waste products therefore need to be converted into nitrates which are not harmful to the fish.

Bio-filters consist of a medium with a large surface area upon which nitrifying bacteria will colonize after a few weeks.

These bacteria will convert toxic ammonia and nitrites into non-toxic nitrates via oxidation. This process is known as nitrification.

There are a number of different bio-filters on the market and some recirculation systems will often incorporate several into their design.

It will usually take a few weeks to a month before nitrifying bacteria colonize and the bio-filter becomes active. During this time stocking and feeding rates should be reduced.

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Sterilizationultraviolet sterilizer filter or treated with ozone to destroy any pathogens, parasites and diseases that may be present.Heating and CoolingHeat exchanges, electric submersion heaters/coolers, or air injection can be used to heat or cool the water.LightingAs the fish are housed within a building, artificial lighting is required to give the fish an impression of a day/night regime. This is to stimulate normal feeding and behaviour patterns of the fish to ensure optimum growth.

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LAYOUT OF A R.A.S

The water is taken from the culture tanks to the mechanical filter unit, where the large SS are being removed.From here the water is then passed to the UV filteration unit, where all the pathogens are destroyed ensuring no disease breakouts in the system.With the help of another header pump, the water is passed to a reservoir unit, from here the water is passed to the bio filter unit where the nitrifying bacterias breaks down the harmful ammonia to harmless nitrate form and send back to the reservoir. From the reservoir the water is send back to the culture unit and the cycle is thus completed.22

Water Quality ManagementTemperatureMaintaining temperature. Fish are also less stressed when held at their optimum temperatures and therefore become less prone to disease.Temperature is maintained using artificial heating or cooling device.

Maintaining temperature within the optimal range for growth of the selected culture species is vital.Fish are also less stressed when held at their optimum temperatures and therefore become less prone to disease.Temperature is maintained using artificial heating or cooling .23

Oxygen

Dissolved oxygen is perhaps the most critical water quality variable and will depend on water temperatures, stocking and feeding rates and the effectiveness of the aeration installed within the recirculation system.

Dissolved oxygen concentrations should be kept around 5ppm to ensure the survival and growth of the culture species.

pH LevelsThe pH is the measure of the hydrogen ion (H+) concentration in the water.

An optimal pH range is between 6.5 and 9 however this will alter slightly depending on the culture species.

Oxygen

Dissolved oxygen is perhaps the most critical water quality variable and will depend on water temperatures, stocking and feeding rates and the effectiveness of the aeration installed within the recirculation system.

Dissolved oxygen concentrations should be kept above around 5ppm to ensure the survival and growth of the culture species.

pH LevelsThe pH is the measure of the hydrogen ion (H+) concentration in the water.

An optimal pH range is between 6.5 and 9 however this will alter slightly depending on the culture species.

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Carbon Dioxide

Produced by the respiration of fish and bacteria within the system.

High levels it--respiratory problems as it will interfere with oxygen uptake and cause stress to the fish.

High carbon dioxide concentrations within the water column can also cause pH levels to decrease as mentioned previously.

Carbon Dioxide

Carbon dioxide is produced by the respiration of fish and bacteria within the system.

If carbon dioxide levels reach high levels it can cause respiratory problems as it will interfere with oxygen uptake.

High carbon dioxide concentrations within the water column can also cause pH levels to decrease as mentioned previously.

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Stock ManagementCulture stock must be managed carefully to ensure the health, survival and growth of the animals.

Stock management consists of : Breeding technologyAvailability of fingerlingsSchooling fishKnown culture technologyRapid growth ratesMarket acceptability

GradingGrading is a particularly important exercise when farming fish using a recirculating system.

Fish will grow at varying rates therefore it is necessary to seperate the faster growing fish from the slower growing fish to prevent cannibalism. The frequency of grading will depend on the species of fish however grading is generally performed more frequently when the fish are younger.

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FeedingFish feed on

Feeding rates--depend on the species.Automatic feeders--less manual labour than manual feeding.Automatic feeders

ZooplanktonLarval stage Dry pelletsFingerling.

Belt feedersConveyor belt drops pellets into the water at regular intervalsDemand feeders Triggering the feed disposal when required.

Fish feed on zooplankton during the larval stage and are then onto dry pellets when they reach fingerling status.

Feeding rates and the type of feed will depend on the species of fish that is to be cultured.

Automatic feeders are useful as they require less manual labour than manual feeding.

Some examples of automatic feeders include belt feeders where feed is placed within a storage area and a conveyor belt drops pellets into the water at regular intervals.

Demand feeders are also available where fish are fed by triggering the feed disposal when required.

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Disease and StressAs fish are held at high densities within the recirculation system they are more at risk of becoming stressed and therefore prone to disease. It is important to monitor fish health continuously as, if a disease outbreak does occur it can spread extremely rapidly throughout the culture tank. Fish farmers usually ensure that tanks can be isolated from one another to prevent a disease from spreading throughout the entire system.

As fish are held at high densities within the recirculation system they are more at risk at becoming stressed and therefore prone to disease. It is important to monitor fish health continuously as if a disease outbreak does occur it can spread extremely rapidly throughout the culture tank. Fish farmers usually ensure that tanks can be isolated from one another to prevent a disease from spreading throughout the entire system.

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Harvesting and PurgingHarvesting is done using nets which are dragged through the tanks. As possible to prevent further stress on the animals.Purging tanks -filled - clean and fresh water. Fish are kept within the purging tanks.This ensures that the "off-flavor" that is often associated with farmed fish is removed and thus will increase their market acceptance.

Harvesting is done using nets which are dragged through the tanks.

This must be achieved as thoroughly and effectively as possible to prevent further stress on the animals. Once the fish have been removed from the culture tanks they are placed within purging tanks which are filled with clean and fresh water.

Fish are kept within the purging tanks for a few days to a week.

This ensures that the "off-flavor" that is often associated with farmed fish is removed and thus will increase their market acceptance.30

ADVANTAGESGrowing season under control.Labor costs automationStock security (predators, disease, theft,pollution) Less dependency on natural resourcesProduction controlMarketing controlDISADVANTAGESHigh construction costsHigh production costsComplexity (electrical., Mechanical., Hydraulic)Need for trained operatives.Electrical reliabilityBack-up components

The following are the advantages as well as the disadvantages of RAS31

The following are the paces in the world where RAS is being carried out in commercial scale

1.. Australis' aquaculture farm produces up to two million pounds of fish per year and discharges less than 15 lbs of solids per day2. Dan speas fish rearing center Built in 1958, this 17-acre rearing station,Species reared at Speas brown trout and rainbow trout3. National Prawn Company (NPC) is the biggest producer of shrimp in the Middle East. The company is now expanding rapidly into fish farming in order to diversify its seafood production. The goal is to reach a total production of 50.000 tons. 4. Millbrook.....Established in 2003, Millbrook, Nova Scotia, Canada The 15,000 sq. ft. contained and controlled aquaculture facility features 10 culture tanks, and associated recirculation equipment.5. Salamar ASA A new Recirculating Aquaculture System (RAS) is to be built with the Primozone GM18 ozone solution in

6.Hayashi is currently in the water salmon and trout fish farm to about 400t and about 10 kinds of farmed fish species

Take an example of Saudi Arabias national prawn Company , we can see that, even though there is heavy scarcity of water in desert area RAS has made the Company to run successfully.

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RAS systems have been further modified for achieving higher productivity by incorporating the technique of AQUAPONICS.

AquaponicsAquaponics is a food production system.

In an aquaponic system, water from an aquaculture system is fed to a hydroponic system where the by-products are broken down by nitrogen-fixing bacteria into nitrates and nitrites, which are utilized by the plants as nutrients. The water is then recirculated back to the aquaculture system.

Aquaponics is a bio-integrated system that links recirculating aquaculture with hydroponic vegetable, flower, or herb production. Recent advances by researchers and growers alike have turned aquaponics into a working model of sustainable food production. This publication provides an overview of aquaponics with brief profiles of working units around the country. An extensive list of resources point the reader to print and web-based educational materials for further technical assistance

Aquaponics is a food production system that combines conventional aquaculture, (raising aquatic animals such as snails, fish, crayfish or prawns in tanks) and utilizes their wastes for growing vegetables using the culture water.

In an aquaponic system, water from an aquaculture system is fed to a hydroponic system where the by-products are broken down by nitrogen-fixing bacteria into nitrates and nitrites, which are utilized by the plants as nutrients. The water is then recirculated back to the aquaculture system.

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CONCLUSIONRecirculating aquaculture system is the key to the future of aquaculture. Its merits outweighs its disadvantages. It makes sustainable use of the water resources, and in places where there is scarcity of good quality water.Even though it has high establishment cost, but the scope of RAS is vast. It is environment friendly, there is control over the production, and the supply can meet the demand according to the market conditions. There is low pollution to the surroundings in recirculating aquaculture systems.

ReferencesAdler, P.R. 2001. Overview of economic evaluation of phosphorus removal by plants. Aquaponics Journal. Vol. 5, No. 4. p. 1518.Balderston,W.L. and Sieburth,J.M. 1976. Nitrate removal in closed-system aquaculture by columnar denitrification. Applied and Environmental Microbiology 32: 808-818.Beecher, L.E., C.G. Lutz, and R. Malone. 2001. Tiltrech Aquafarm: A prototypical greenwater greenhouse recirculating systems. Pp 271-283. In: 2001 AES Issues Form, Aquacultural Engineering Society proceedings IV. NRAES Publication No. 157. Natural Resource, Agriculture, and engineering Service, Cornell University. Ithaca, New York.Chen, S., M.B. Timmons, D.J. Aneshansley, and J.J. Bisogni, Jr. 1993. Suspended solids characteristics from recirculating aquacultural systems and design implications. Aquaculture 112:143-155.Colt, J. 1986. An introduction to water quality management in intensive Aquaculture. Pages 1-16. In:H. Lorz, convener. Section 6. Uses of supplemental oxygen. Northwest Fish Culture Conference, Eugene, Oregon.

www.emperoraquatics.com/aquaculture-recirculationsystems.php#.Uo3Mp9JHJqUwww.dpi.vic.gov.au/fisheries/aquaculture/aquaculture-management/guidelines-for-recirculating-aquaculture-systemsweb1.cnre.vt.edu/extension/fiw/fisheries/fishfarming/RecirculateAquaSys.html