Factory shrimp farming occupies less space, high yield, good benefits, can avoid the traditional shrimp farming methods brought about by shrimp disease and water pollution, and reduce the adverse effects of the weather on the breeding. China's coastal shrimp farming after years of development, factory shrimp farming has a certain foundation, some areas of factory farming has reached the world's advanced level, but overall the basic use of "cement pool + greenhouse" as the core of the intensive mode. Better economic benefits, but there are still aeration equipment, energy consumption is too high, most of the wastewater can not be effectively dealt with and other issues. Europe and the United States and other Western countries in the factory of circulating water shrimp aquaculture system made a number of attempts and research, it is worthwhile to learn from us.
In the shrimp disease rampant at the moment, the whole process of controllable factory farming may be a new idea and direction.
For a single culture species, South American white shrimp in 2008, the global output value is the highest, amounting to 9 billion U.S. dollars. Shrimp is the world's most important fish trade commodities, accounting for about 15% of total world fish trade. Shrimp farming is currently plagued by shrimp diseases, with Ecuador, Thailand, and China increasingly threatened by shrimp diseases since the 1990s. It is estimated that some countries and regions in Asia in the 1990s due to disease causes losses of up to several billion dollars. Shrimp factory farming is the use of industrial means to control the ecological environment in the pool, to create an optimal survival and living conditions for shrimp. In the high-density intensive stocking conditions, put high-quality feed, to promote the smooth growth of shrimp, for a higher economic efficiency of the breeding mode. In the shrimp disease rampant at the moment, the whole process of controllable factory farming may be a new idea and direction.
Western countries such as Europe and the United States have done a lot of attempts and research in the factory farming system of circulating water shrimp. Factory farming is broadly divided into three forms: flow-through aquaculture, semi-closed recirculating water culture and fully closed recirculating water culture. The whole process of flow-through aquaculture are realized open flow water, used water is no longer recycled and treated, the amount of flow water exchange is 6-15 times per day; semi-closed recirculating water aquaculture method of aquaculture water is not completely open, but part of the aquaculture wastewater by precipitation, filtration, disinfection and other simple treatment and then flow back to the breeding pool for reuse; fully closed recirculating water aquaculture method of aquaculture water after the city store, filtration, removal of soluble Harmful substances, disinfection and other treatments, and then according to the physiological requirements of shrimp at different stages of growth, temperature regulation, oxygenation, and replenishment of the appropriate amount of fresh water, and then re-conveyed to the breeding pool, repeated recycling.
Shrimp recirculating aquaculture system should be able to meet the shrimp growth of water quality, water temperature, salinity conditions, and to ensure that there is a certain amount of water flow, to promote the drainage of the breeding pool and meet the physiological needs of shrimp. Loop channel shrimp farming system, Florida three-stage shrimp farming system, as well as microalgae-based recirculating water shrimp aquaculture system have achieved better breeding results. At present, the level of development of China's factory farming system is still in the primary stage of development, in recent years, the shrimp factory recirculating water aquaculture system research has also achieved a lot of results.
Factory shrimp aquaculture should be based on different areas of water quality conditions and farming habits, the formation of local conditions suitable for the local application of closed recirculating water aquaculture model. For example, in South America, more runway type recirculating water aquaculture, standing water aquaculture, micro-flow closed recirculating water aquaculture and other modes; China's East China Sea, the Yellow Bohai Sea area more than closed recirculating water aquaculture; tropical, subtropical coastal areas more closed, semi-closed micro-exchange of water factory farming mode. South China's coastal areas of high water temperature, long hours of light, the sea is rich in biological resources, according to its characteristics to take full advantage of the natural geographic resources, reduce temperature control facilities to reduce energy consumption, the introduction of micro-organisms, rich in algae, large and medium-sized aquatic plants and other elements, so as to build a suitable for the characteristics of subtropical areas of the environmentally friendly shrimp closed recirculating water aquaculture model. Water treatment technology
1/4 page
Shrimp ponds in a variety of forms, generally long rectangular, circular, oblong, runway type. It is generally agreed that the runway type shrimp pond effect is better, the advantage is that the pool water can flow in the circular pool, on the one hand, can make the pool water quality is balanced, and can be shrimp feces and residual bait timely discharged out of the pool, to maintain a good quality of water in the pool. A certain direction of water flow is also in line with the physiological characteristics of shrimp, is conducive to the growth of shrimp.
Shrimp farming first water, the reason for aquatic people understand. In shrimp factory farming, water treatment technology is also the main event in the system. According to the different treatment methods, there are mainly physical filtration, biological treatment, disinfection and sterilization methods, these methods are often used according to the actual situation **** with, and artificial intervention of dissolved oxygen and temperature, salinity. Physical filtration is the first link in circulating water aquaculture water treatment, but also an important link. Its main purpose is to get rid of particulate organic matter suspended in the water and plankton, microorganisms, etc., rapid and timely removal of particulate organic matter in the water, can greatly reduce the load of biological treatment. At present, the common physical filtration methods are sand filtration, mesh bag filtration, rotary drum microfiltration, curved screen filtration and so on.
Biological treatment plays a central role in the aquaculture system, good water quality depends on it to maintain. It is mainly to remove organic matter, ammonia, nitrite and other toxic substances in the water. The usual biological treatment is to use nitrifying bacteria to oxidize ammonia nitrogen and nitrite into nitrate, eliminating their toxic effects. According to the way of microbial growth can be divided into suspended and solidified. In the aquaculture circulating water treatment system, microorganisms mostly use solid growth, more representative systems such as drip filter, submerged filter, plastic bead packing filter, sand fluidized bed filter, biological rotary filter, biofilter, biofilter tower. There are also the use of microalgae, macroalgae, hydroponics, etc. to remove ammonia nitrogen, such as: artificial wetland technology, fish and vegetable *** living system, fish, shrimp, shellfish, algae ecological treatment system, microalgae-based shrimp aquaculture system.
In the high-density farming conditions, in addition to the presence of physical and chemical pathogenic factors in the water body, there are a certain number of pathogenic bacteria, conditionally pathogenic bacteria. This will not only consume a lot of dissolved oxygen in the water body, but also have a serious negative impact on the breeding of shrimp. The system should be equipped with disinfection and sterilization equipment, the use of physical and chemical measures to reduce the impact of factors on the shrimp. Common disinfection equipment include ultraviolet sterilizer, ozone generator, chemical sterilizer. Ultraviolet sterilizer disinfection effect is slightly worse, but its side effects are small, better safety; chemical sterilizer disinfection effect is better, but if not used properly may cause secondary pollution of aquaculture water; ozone disinfection should be a reasonable grasp of the ozone content of the water, the disinfected water can not be immediately entered into the aquaculture system, and should be aeration for a period of time, so that the ozone in the water body is reduced to a safe concentration to be re The use.
Dissolved oxygen is the most important parameter in the shrimp aquaculture ecosystem. The level of dissolved oxygen in the aquaculture water body directly or indirectly affect the growth and development of shrimp. To maintain sufficient dissolved oxygen, oxygenation is an important part of the aquaculture system. At present, the common way of oxygenation is mechanical oxygenation, air blower oxygenation, pure oxygen oxygenation and so on.
In order to realize multi-crop farming, continuous production, the need to use temperature regulation device. Generally, it is equipped with a set of temperature increasing device to ensure that the breeding production is not limited by the low temperature environment. The more commonly used is the boiler tube heating system, electric heaters (rods) system, can also be used in solar energy, wind energy, geothermal energy and other green energy.
Shrimp recirculating aquaculture system main mode
1. Texas, the United States, runway shrimp farming system
System mainly consists of: the runway type culture tank, oxygenation device, solids suspended solids removal equipment (rotary drum microfilter and protein separator). The aquaculture water is recycled through the rotary drum microfilter, protein separator, biofilter and ozone reaction device after treatment. In the aquaculture tank, pure oxygen is dissolved into the water by using a jet streamer, and a certain direction of water flow is formed. Using a runway-type shrimp culture tank with a length of 13.0 m, a width of 2.53 m and a height of 0.85 m for the culture of South American white shrimp, the shrimp were cultured for 146 d at a stocking
2/4 pages
cultivation density of 2,132 tails/m3, with a yield of 11.4 kg/m3 per unit area, and the shrimp body averaged a body weight of 14 g at the time of harvest, with a survival rate of 48%.
2. Tainan Indoor Automated Circulating Water Shrimp Farming System
System components mainly include the main structure (roof frame and shrimp pond), circulating water treatment equipment, automatic monitoring system. Shrimp pond for reinforced concrete structure, the size of each pool are 6m × 6m × 2m, shrimp water body is 50m3; 2 small shrimp pond, ***100m3 water body; 12 shrimp pond, ***600m3 water body; 22 large shrimp pond, ***1100m3 water body. The circulating water treatment equipment includes physical filtration equipment (rotary drum microfilter), sterilization equipment (quantum electrocoagulant machine), biological treatment device (biofilter bed) and oxygenation device (oxygen cone); the automatic monitoring system includes automatic monitoring of water quality, automatic baiting, and automatic heating system.
Five phases of aquaculture trials were conducted at the experimental field of the Tainan Branch of the Taiwan Provincial Aquatic Experimentation Institute, where grass shrimp and South American white shrimp were raised to marketable specifications. Among them, in the 5th phase of South American white shrimp culture, the stocking density was 2167 tails/m3, the harvest was 363.6 kg, the culture period was 105 d, the yield per unit area was 11.23 kg/m3, and the average weight of shrimp body was 10.5 g at the time of harvest, and the survival rate was 49.5%.
3. Three-stage aquaculture system in Florida, USA
The system consists of three aquaculture zones: hatchery zone (11%), nursery zone (31%) and adult shrimp culture zone (58%). The bottom of each culture area is connected to each other through 100mm threaded divider streets, which facilitates the dumping of shrimp. The system divides the shrimp culture process into 3 separate culture stages: juvenile, intermediate and adult shrimp. Each stage is accomplished in a different culture tank in the system. Juvenile shrimp are initially placed in 1 small culture tank, which covers 10-13% of the total area of the system. After 50-60 d of culture, the grown shrimp were transferred to a 2nd culture tank with 27%-30% of the total tank area, and after 50-60 d, the shrimp were finally transferred to the largest culture tank with 60% of the total tank area. After another 50-60d of culture, the shrimp can reach the market specification.
The aquaculture pools are of the loop channel type, which utilizes the push-flow of circulating return water to promote the drainage of the shrimp pools, so that residual bait and feces in the pools can be discharged from the system in a timely manner. The circulating water treatment mainly adopts sand filter and biological filter, and maintains a certain concentration of microalgae in the aquaculture pool. The system uses a high volume, low head centrifugal pump to provide a flow rate of 4.5 m3/h, which drives the water flow. The well water is degassed, treated with biofilters and then entered into a dark storage tank for backup.
4. Hawaii, USA Recirculating Water Shrimp Aquaculture System
In the water recirculation aquaculture system of shrimp, microalgae and shellfish***, microalgae are utilized to absorb the total ammonia nitrogen dissolved in the water in shrimp ponds, and the microalgae serve as the bait for the shellfish in the system in order to maintain a balance of the total biomass in the system. The use of high-density microalgae water for shrimp culture can inhibit the occurrence and spread of viral diseases in shrimp.
The system consists of four shrimp ponds with a diameter of 20m, four groups of 30m×6m rectangular shellfish ponds and supporting pumps and pipelines. The photosynthesis of diatoms (Diatom spp.) is utilized to absorb the ammonia nitrogen produced due to the decomposition of shrimp excreta and bait residues; the diatoms can also be supplied to the Philippine clams through water recycling. The shrimp-algae-shellfish recirculating aquaculture system being operated by Kona Bay Marine Resources in Hawaii, USA, has been shown to operate normally with only a 10% daily water change rate. The system is capable of producing 25 pairs of parental shrimp and 600,000 intermediate 6-8mm Philippine clams per square meter of water per year.
5.35m3 Semi-closed Recirculating Water Aquaculture System
The system is based on a series of air-lift pumps driving the water at a flow rate of about 280 L/min. Aquaculture pond drainage enters a microfilter for physical filtration and passes through an air-lift into two separate parallel foam separators. The water is precipitated and clarified in the settling zone, and enters a counter-current biofilter, then degassed and ozonized in a secondary settling tank, and finally returned to the breeding tank.
6.72m3 Runway Type Recirculating Water Aquaculture System
The system is driven by a series of air lift pumps with a flow rate of approximately 720 L/min. The water from the aquaculture tanks passes through a microfiltration
3/4 page
machine or bypasses the microfiltration machine and goes directly to the settling tank. Ozone is passed to the bottom of the sedimentation tank to promote flocculation and aggregation of particulate organic matter. The settled particulate organic matter is discharged through the bottom of the settling tank. After settling, the water is passed through an airlift into three parallel biofilters and then into a foam separation/ozone reactor. Ozone is injected into the reactor through jets. Finally, all the water enters the degassing settling tanks and then flows back to the culture tanks. The shrimp culture density of this system can be as high as 10kg/m3.
7. Wetland type shrimp closed recirculation water culture system
This system has a culture tank of 12m3, with an artesian type being a drop of about 4m3, and a submerged wetland of about 4m3, and the control group being an identical tank, but with no recirculation of the water body. The artesian wetland consisted of a 0.3m soil layer and 0.4m deep artesian water. The submerged wetland contained a 0.6m thick layer of pebbles (10-20mm in diameter, with a void ratio of about 45%) and a submerged water layer at a depth of 0.4m. The self-flowing wetland is about 0.3m above the submerged wetland, and both wetlands are planted with hydrilla reeds, with a density of 100 reeds/m2. The flow rate of the water in the system is about 0.12m3/h. The advantages of this system are that it does not require mechanical equipment (except for pumps), has low energy consumption, and is simple and convenient to operate and maintain. The disadvantage is that the wetland occupies a large breeding area.
8. Shrimp and prawn closed recirculation aquaculture system
The system uses bead biofilter to effectively remove particles larger than 15 microns of organic matter, and at the same time there is a certain biological filtration. Bead biofilter can efficiently remove particles of organic matter, backwash with less water, not easy to clog, suitable for shrimp aquaculture water treatment. Biological filtration through the sulfide sand bed. The system is biologically safe, shrimp spawning rate and hatching rate increased significantly