With China's economic and social development entering a new period, under the influence of multiple factors such as increasing market demand and shortage of land resources, the factory farming of prawn has developed rapidly in recent years, and its area and output have been increasing continuously. However, it is mainly based on the relatively extensive aquaculture model. There are widespread problems such as waste of groundwater resources, frequent diseases, unstable success rate of aquaculture and serious organic pollution of discharged water. Industrial circulating water efficient ecological aquaculture technology for shrimp as the main aquaculture object, relying on modern aquaculture engineering and water treatment facilities, comprehensive use of micro-pore oxygenation, immune enhancement, water quality control, aquaculture tail water treatment and other technologies, to achieve efficient and ecological aquaculture of shrimp throughout the year. With the obvious characteristics of water body recycling, ecological environment stability, artificial regulation of aquaculture process, tail water discharge standard, it is a new model of prawn aquaculture in line with the concept of "high efficiency, high quality, ecology, health and safety" in the new era of our country. In recent years, the aquaculture technology has been popularized and applied in the shrimp aquaculture enterprises in Qingdao, Weifang, Yantai and other places in China's Shandong province, the aquaculture output has reached 4.3kg/m2, saving more than 90% of the aquaculture water, and the aquaculture tail water meets the "Marine aquaculture water discharge requirements" (SC/T9103-2007) the secondary standards. Especially in the low temperature season in the northern region, the application of this aquaculture technology can not only save energy consumption in part of the heating link, but also the aquaculture water environment is more stable than that of water exchange aquaculture, and the effect of energy saving and emission reduction is obvious, and the industrialization prospect is very broad. This technology is one of the important ways to promote the transformation of mode and structure of prawn farming industry in China and realize "quality and efficiency improvement and green development", and also has great significance for efficient utilization and protection of precious water and soil resources.
1.1 Facilities and Equipment
It mainly includes four parts: reservoir, aquaculture tank, water cycle treatment equipment and outdoor tail water treatment tank. The aquaculture tank, reservoir and water cycle treatment equipment can be set in the closed and good thermal insulation breeding workshop. The roof above the aquaculture tank and reservoir is transparent, and the water cycle treatment equipment placement area, especially the biological filter, should be shielded from light.
(1) Reservoir: the water capacity of the reservoir should not be less than one-third of the total water body and can be completely drained, mainly for salinity deployment and disinfection treatment, etc., can be used for ultraviolet, ozone or bleaching powder disinfection treatment.
(2) Aquaculture pond: rectangular rounded or circular shrimp pond, mostly made of cement or fiberglass, with an area of 25 to 100 square meters and a water depth of 0.8 to 1.2 meters. The bottom of the pool is smooth and smooth, with a sewage collection area and a drainage outlet in the center, and a 3-5% slope towards the drainage outlet, and a strip of nano-microporous oxygen increasing tube near the bottom of the pool and the junction of the pool wall, which is conducive to water pollution collection and rapid discharge while ensuring adequate oxygen supply of the breeding pool. An independent circulating return water pipeline and a sewage pipe are arranged at the drainage outlet, which are connected to the circulating water treatment system and the outdoor tailwater treatment pool respectively. The usually clean aquaculture water enters the circulating water treatment system through the return water pipeline, and the sewage pipe is opened and discharged into the tailwater treatment pool when sewage operation is required.
（3）Water cycle treatment equipment:
Filtration of suspended particles: commonly used equipment are micro filter and curved screen, etc., to the micro filter is appropriate, the effluent water quality is better (can improve the water quality by adjusting the screen mesh, speed and recoiling pressure); The curved screen does not need power and cleaning water, and the cost is relatively low, but the effluent quality is general.
Removal of fine and dissolved particles: the protein separator can remove 70% of the organic matter in the water before it is decomposed into harmful substances such as ammonia/ammonium salt, which is mainly composed of a gas diffusion device, a reaction vessel (usually cylindrical) and a foam collection device, etc., and can artificially adjust the water inlet diameter, outlet diameter and flow rate of the protein separator according to the water quality and water circulation volume.
Biological purification: Biological filters that are commonly installed or placed with biological filter materials are mainly used to degrade harmful substances such as ammonia nitrogen and nitrous nitrogen in water bodies by strengthening the role of microorganisms. The biofiltration material can choose PVC elastic three-dimensional filler or PVC porous ring, the filling rate is 20~50%, and the number should be determined according to the basic biological carrying capacity of the circulating water system. The ratio of the volume of the effective water body of the biological filter and the effective water body of the aquaculture tank should be 1:3-1:5, and the aeration device is set at the bottom, and the small blower is used for gas supply.
Disinfection and sterilization: Use ultraviolet disinfection device or ozone generator for sterilization. Ultraviolet sterilization uses a channel device, and generally chooses a lamp with a wavelength of 240 to 280 microns. The output range of the ozone generator device is 2.5~65 g/hour, and the addition of an ozone flowmeter to ensure the ozone input concentration of 0.08~0.20 mg/l, and the water body after ozone disinfection should be fully aerated before it can enter the aquaculture water body.
