Zero water cultu. sys.(ras) me

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jitenderanduat@gmail.com

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.

Tank Culture. Concrete, fiberglass? Indoor or outdoor? Static or water exchange?

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.

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.

Bio-filter (1) Submerged bed filters (2) Emerged bed filters.

Bio-filtration for NH3 removal

jitenderanduat@gmail.com AQUAGRIS WORKSHOP (Bremen, GERMANY) - Saturday 9th February 2008

NITRIFICATION / DENITRIFICATION

NO3- N2NO2

- NO N2O

NH3/NH4+ NO3

Nitrification:

Denitrification (Anaerobic processes):

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.

Thank You

Zero water cultu. sys.(ras) me

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