Introduction: Hello aqua farmers today we have a great information on shrimp RAS farming system design, construction cost etc.. Recirculating aquaculture system (RAS) is a technology for farming of aquatic animals in which the method of water is continuously reconditioned and reused. The use of a closed aquaculture system including Recirculation Aquaculture System (RAS) has been implemented to allow a more stable water quality, excellent hygiene and efficient use of water resources in wide shrimp aquaculture production.
A guide to Shrimp RAS farming, construction, price
Recirculation system includes Biofiltration, Ozanation Oxygen Generation which in terms helps us to keep good water quality and yield in higher production. These systems occupy a small area which allows the grower shrimp at high densities and produce high yields per unit area. Recirculation systems are becoming popular as they give a predictable and constant environment for growing shrimp.
Recirculating aquaculture system (RAS) farming is the culture system of the future. As with other forms of animal agriculture, moving indoors offers benefits in terms of biosecurity and year-round production. However, RAS is the most technologically challenging and currently the most expensive method to raise shrimp. Recirculation aquaculture system (RAS) or often called the recirculation system is an innovation culture system that suitable to be applied to limited land and water.
The aim is to improve water quality so water can be used continuously. The movement of water will cause the distribution of environmental factors in the form of temperature, oxygen, pH, and others to be evenly distributed; even the spread of food is also evenly distributed, besides the impurities and metabolic waste from fish will be carried away by the movement.
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RAS systems offer major environmental advantages in terms of lower water consumption during production and zero discharge of waste. “For example, to generate 1kg of harvested shrimp takes 1m3 to 1.5m3 of water in a RAS system, whereas the outdoor farms use more than 5m3. This is the main saving in terms of cost and it’s better for the environment.” The main benefit of the RAS system is the ability to reduce the need for fresh, clean water while still maintaining a healthy environment for shrimp.
RAS system function
A key feature of the RAS system is that it re-uses water; the water is recirculated continuously throughout the system. All of the tanks and several components in the RAS system are connected by pipes. Water flows from the shrimp tank to the mechanical filter where solid waste is removed. The water then flows into a biological filter then that converts ammonia to nitrate. Some RAS incorporate plant tanks as biological filter plants absorb nutrients, therefore “cleaning” the water. Other systems use special tanks that are designed to promote good bacteria and bacteria act as a filter. After being “treated” in the mechanical and biofiltration components, the water flows back to the shrimp tank.
Shrimp RAS design and construction
The RAS farming was composed of six rearing tanks, each directly receiving water pumped from a sump tank while directly discharging water into a biofilter. Influent flow to each rearing tank was mainly controlled by a ball valve. Water from each rearing tank was discharged through vertical standpipes, the height of which set water depth and volume. Four of the rearing tanks each held 80 L, while the other two each held 530 L. All standpipes were covered with plastic mesh to exclude shrimp and to minimize footprint, the rearing tanks were stacked in three tiers, with four small tanks on a platform above two large tanks.
RAS offers optimal growth conditions all year round. Stock is protected from predators and pathogens and water quality and the temperature are continuously monitored.
All modern RAS systems normally have the following components;
- Solids collection systems (a rotating drum filter)
- A foam fractionation unit also called as a protein skimmer or dissolved air floatation device
- Carbon dioxide degasser
- Nitrate filter
- Sterilization points (usually UV sterilization)
- A tank drainage system that separates wastes from main outflows
- Temperature control (heat pump or evaporative cooling)
- Heat exchange of effluent waters
- Oxygen injection system
- A pH control and alkalinity dosing system.
The biofilter was sized to give enough total ammonia nitrogen (TAN) removal capacity to maintain sufficiently low TAN concentrations in the RAS, resulting in a biofilter volume of 350L. Water flowing from standpipes in each rearing tank was carried by gravity to an inlet on one end of the biofilter system, and displaced water exited through an outlet on the other end. At the outlet, horizontal pipe discharged water from the biofilter into the sump tank. It was sized to accommodate water from one large rearing tank, providing a 440-L capacity, to avoid discharging water from the RAS system when draining tanks to facilitate shrimp harvest. The sump tank was the tank in which water level can vary due to evaporation and manual filling, and the water level was maintained at between one-half and one-third of tank depth during standard operation. Water was continuously drained from the sump tank to all rearing tanks by a 79.2-W pump. All pipes and fittings used in RAS plumbing were PVC pipe, with joints solvent-welded with pipe cement. To seed, the biofilter with microbes adapted for nitrification in saltwater, about 35 L of wet sand was collected from the sand filter of a shark exhibit backwash recovery system at the Shed Aquarium and placed into the RAS biofilter.
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Nitrification was established by the daily addition of ammonium chloride for two months before stocking the first batch of shrimp into the RAS system. Continuous aeration was provided by three circular air stones connected to an air pump. Because rearing tanks were quite shallow, holding water 8 inches deep with 3 inches freeboard, shrimp were frequently lost from the system by jumping over the sides of rearing tanks. After five months, an attempt was made to retain shrimp by securing plastic netting over the tanks. While this reduced the incidence of shrimp escapement, the netting was not able to prevent it. Subsequently, around 8 months into RAS operation, custom-made screens were installed to enclose all rearing tanks. The screens were constructed from rigid plastic mesh, secured on all sides to an aluminum frame clamped to the top of each tank. Mesh screens for small tanks each contain an opening that allows access for feeding and taking measurements without needing to remove the screen. When not in use for tank access and these openings were covered with a flexible mesh fabric held secure by elastic cords. These screens effectively prevented shrimp from jumping out of rearing tanks.
The whiteleg shrimp RAS
The production site of the RAS farm facility was built inside of an isolated construction with a size of about 1.300 sqm and a total water volume of 400 cbm of water. The water management is mainly based on full recirculation technique (RAS) and the volume allows the production of about 500 shrimps at a time. From larvae to market size (25-30g) about 6 months are necessary under the given farm conditions. The farm aims to generate about 15t of Whiteleg Shrimp per year.
The whiteleg shrimp (Litopenaeus vannamei) is also known as Pacific white shrimp. It is an eastern Pacific Ocean shrimp commonly caught or farmed for food. Whiteleg shrimp is a marine crustacean belonging to the order Decapoda and the family Penaeidae. The body is translucent and often has a bluish-green hue due to the occurrence of pigmented chromatophores (molecules evolved to collect or reflect light).
Advantages of L. vannamei for RAS production
The artificial reproduction of the species has become a routine process and larvae are available year-round from specialized hatcheries, a matter of fact which is important for facilities that operate independently from environmental conditions. Whiteleg shrimp larvae for on-growing farms are certified for more than six generations as specific pathogen-free stocks and can provide healthy larval stages. Larval stages of white leg shrimp are in general robust with low mortality and can be quickly adapted to lower salinity. The species is fast-growing (1-3g/week) and allows relatively high stocking densities which facilitate the economical operation of the facility although it does not harm the welfare of the individuals.
Water quality management in shrimp RAS farming
In any shrimp RAS farming, management of water quality is of primary consideration particularly in ponds with higher stocking rates. Degradation of water quality management is detrimental to shrimp growth and survival. Good quality water is generally defined as the fitness or suitability of the water for survival and growth of shrimp. During 84 days of growing out period, all physicochemical water quality parameters in all shrimp densities were intolerance level for shrimp RAS culture. This suggests that the continuous use of RAS can keep stable water quality parameters even at high stocking densities of up to 1,000 PL/m3 with a high organic load to the system. Though, slightly lower inorganic nitrogen compounds of ammonia and nitrite were observed in the lowest shrimp density compared to the higher shrimp densities.
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The pH level of the pond water is indicative of its fertility or potential productivity. Water with pH ranging from 7.5 to 9.0 is generally regarded as suitable for shrimp RAS production. The growth of shrimps is retarded if the pH level falls below 5.0. Water with a low pH level can be corrected by adding lime to neutralize the acidity.
The water of excessive alkalinity (pH values > 9.5) can also be harmful to shrimp growth and survival. In ponds that are excessively rich in phytoplankton, the pH level of pond water usually exceeds 9.5 during the late afternoon. However, at daybreak, the pH is generally lower and excessive plankton growth can be corrected by water exchange.
Temperature for Shrimp RAS farming
Water temperature plays an important role in regulating the activities of the cultured animal. The rate of chemical and also biological reactions is said to double every 10°C increase in temperature. This means that aquatic organisms will use twice as much dissolved oxygen and chemical reactions will progress twice as fast at temperature 30°C than 20°C. So, that dissolved oxygen requirement of aquatic species is higher in warmer than in cooler water.
Many Penaeid shrimp species are tropical or subtropical species. The optimum temperature is about 25 to 30°C and hence many of the species such as P. indicus, P. monodon, and P. merguiensis can be cultured throughout the year while the species P. japonicus and P. orientalis are mainly limited to the summer growing seasons only.
Cost of Recirulatory aquaculture system
The cost of the Recirulatory aquaculture system is approximately Rs 3 Lakh/Unit.
Shrimp RAS farming advantages
The advantages of recirculating aquaculture systems are given below;
- RAS requires significantly less water than that of ponds or raceways and can be located in more areas.
- This system can be more intensive (culturing more products in a smaller volume) and it can produce year-round.
- RAS shrimp production can promote versatility in terms of location for farming, proximity to market and construction on brown-field sites. However, they still require being near source water supplies and consideration needs to be given to local water quality and aesthetics since RAS farms resemble industrial buildings.
- Enable production of a broad variety of species irrespective of temperature requirements provided costs of temperature control beyond ambient are energy efficient and enable secure production of non-endemic species.
- Feed management is potentially greatly enhanced in RAS farming when feeding can be closely monitored over 24h periods. The stable environment promotes consistent growth rates throughout the production cycle to market size provided the operator and RAS has taken into account the diverse range of water quality management issues. Optimum environmental conditions promote good FCRs with some high-value marine species achieving market size in 50% of the time taken in sea cages.
- The advantages of RAS in terms of feed management assume the operator can accurately control and record biomass, mortality rates, and movements across the farm. Efficiency in these tasks becomes increasingly very important with increasing farm size.
- RAS offers shrimp producers a variety of important advantages over open pond culture. These have a process to maximize production on a limited supply of water and land, nearly complete environmental control to maximize shrimp growth year-round.
- In the RAS system, the flexibility to locate production facilities near large markets, complete and convenient harvesting, and quick and effective disease control.
- RAS can be of several sizes ranging from large-scale production systems (over 1 million pounds per year) to intermediate-sized systems (500,000 pounds per year), to small systems (50,000 pounds per year).
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