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Jitendra Kumar DFK 1303 Resources and Management College of Fisheries, Mangalore Zero water exchange culture system (Close Aquaculture System) [email protected]
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Jitendra KumarDFK 1303
Resources and Management
College of Fisheries, Mangalore
Zero water exchange culture system(Close Aquaculture System)
Closed Aquaculture Systems
Closed system aquaculture refers to the land-based rearing of aquatic species in raceways, tanks and ponds.
Recirculation technology is implemented which cycles water through filtration processes and returns it back into the aquaculture system.
This process aids in maintaining water quality whilst ensuring minimal exchange with natural waterways.
Types of Culture Extensive (few organisms per aquatic space). Semi-Intensive (more organisms per space). Intensive (many organisms per aquatic
space). Super Intensive (too many organisms per
space).
Aquaculture Systems.
Traditional extensive system
1) Where no exchange of water2) Food is natural3) Natural seed stocking in traditional
system4) Production - not fix5) Operated in - pond
Zero water exchange system
1) Seed stocking done from hatchery
2)Low seed stocking
3)Artificial feed will be provided
4) No water exchange/ just for maintaining water
5)Production- 500to 800 kg/ha
6)Followed for- shrimp, IMC, Seabass in some part of India
7) operated - only in pond
Modern Zero water exchange System
It is also known as re-circulating Aquaculture Systems (RAS). Or indoor culture system.
Recirculating aquaculture systems (RAS) are the newest form of fish farming production system.
RAS are typically an indoor system that allows for farmers to control environmental conditions year round.
RAS
While the costs associated with constructing a RAS are typically higher than either pond or cage culture.
RAS are the most complex aquaculture systems.
It is land based system.
Conducted in
Circular cement tanks Reinforcement circular cement tank Reinforcements Rectangular tank Circular fiber tank Circular rectangular tanks.
Background
The most intensive systems used for production of aquatic organisms are re-circulating systems
Total environment is controlled
Key operating parameters: minimal energy input and proper water quality management
Water circulates through the entire system and only a small portion of new water is added daily
Cont.. Physio-chemical parameters must be
controlled: temperature, salinity, pH, alkalinity, chemical composition, oxygen
Solid wastes are filtered, water is re-oxygenated and re-circulated water undergoes nitrification
Re-circulating aquaculture systems are more capital-intensive than most other types of traditional production systems
Rely on economic productivity per unit volume of rearing space for profitability
Cont.. Must have support facilities (e.g., backup
generators) whose cost is also part of overall production costs for the farm
Large production levels are achieve via modulation of individual self-sustaining units
Production units are also designed for species flexibility – essential now-a-days!
THE RAS DESIGN (1) Growing tank, (2) Sump of particulate removal device, (3) Biofilter, (4) Oxygen injection with U-tube aeration and, (5) Water circulation pump. Depending on the water temperature and
fish species selected. A water heating system may be necessary.
o 6) Ozone and ultraviolet sterilization also may be
advantageous to reduce organic and bacteria loads.
,
Water supply
Quality and Quantity water. Ground water obtained from deep
wells. Springs is the best source of water Free of pollutants. Municipal water supplies also can be
used after chlorine, floride, and other chemicals areremoved.
Bio-filtration The biological filter (biofilter) is the heart of the RAS. Two primary water pollutants that need to be
removed (1) fish waste(toxic ammonia compounds) excreted
into the water. (2) uneaten fish feed particles
The biofilter is the site where beneficial bacteria remove (detoxify) fish excretory products, primarily ammonia.
[email protected] AQUAGRIS WORKSHOP (Bremen, GERMANY) - Saturday 9th February 2008
NITRIFICATION / DENITRIFICATION
NO3- N2NO2
- NO N2O
NH3/NH4+ NO3
-+ O2
NO2-
Nitrification:
Denitrification (Anaerobic processes):
Pers
pect
ives
Her
bivo
ry
S
apro
phag
y
In
trod
ucti
on
Water requirementsMost RAS require less than 10% of the water and much less land than ponds to grow the same amount of product
At the same time, produce continuous crops (i.e., no seasonal impacts)
RAS offer a high degree of environmental control, mitigating risks such as natural disaster, pollution and disease
Other at production systems with low environmental impact
Effect: production brought closer to the consumer
How Much Water is Required?
For site selection of RAS, one must think in terms of the initial facility and eventual modular expansionSource capacity:
fill all tanks within 24-48 hprovide for routine/emergency flushing of tanksfilter backwashingwashdown and clean-updomestic requirements
This is usually over 100,000 gpd with a process flow rate of >70 gpm
Benefits to Recirc. Use of Water
Decrease in water demand
Reduced overall discharge water
Reduction in water heating/cooling
Almost total control over water quality factors
Optimization of land use
Modulation potential = biosecurity
Reduction treatment costs of discharge streams
Types of RAS
Serial re-use, partial re-use, and fully re-circulating systems
Serial: water from one system is enriched with oxygen and goes to a subsequent one Partial: additional treatment of a portion of the system water volume, then re-used
Fully recirc: very high degree of re-use, more treatment processes, systems separate
Major limiting factor
oxygen (determines density), followed by unionized ammonia and carbon dioxide
(CO2 affects pH, pH affects proportion of ammonia
that is unionized).
Stocking Rates of fish
L = 0.06(Dfish/R)
How many fish/shrimp can I put in the system?
“Loading” refers to the fish mass that can be maintained per unit of flowing water: kg/l or lbs/g
Loading capacity depends upon water quality, fish/shrimp size, species (mainly for fish)
SPECIES TO BE CULTURED RAS are currently being used to grow Catfish, Sea bass, Tilapia, Blue crabs, Oysters, Mussels Aquarium pets.
Recirculation Rates 45 gallons per minute (63,360
gallons per day)Feeds and Feeding A complete feed, containing all the
essential minerals and vitamins. Feed of dry, floating pellets Are fed 3 to 5 percent of their body
weight Automatic feeders and demand
feeders
Major problems in aquaculture. Environment needs filtering. Oxygen needs to be replenished. Organisms cannot be seen. Diseases spread too fast. The inside of organisms is
constantly in contact with outside medium.
Therefore, the systems should:
Keep the medium acceptable for survival and optimal growth.
Replenish oxygen and remove carbon dioxide.
Make organisms accessible for inspection.
Fight diseases. Just make it comfortable for the
organisms.
