Industrial aquaculture tail water treatment method

Abstract

The invention belongs to the technical field of tail water treatment, and particularly relates to an industrial aquaculture tail water treatment method. Physical, biological and chemical treatment means are combined, tail water can be efficiently treated within a short time, the occupied area and the operation cost of treatment equipment are reduced, and high economical efficiency and practicability are achieved. Spirulina is combined with bacillus licheniformis, bacillus subtilis and micrococcus luteus for use, so that a stable phycomycete symbiotic system can be formed in a water environment, removal of nitrogen and phosphorus in culture tail water is accelerated, and chemical oxygen demand (COD) in the tail water can be effectively reduced; after the tail water is treated by the method disclosed by the invention, the recycling rate of the tail water is not lower than 80%, and the quality of the treated tail water can reach the national discharge standard.

Description

Technical Field

[0001] The present invention belongs to the technical field of tail water treatment, and particularly relates to a method for treating factory aquaculture tail water. Background Art

[0002] With the rapid development of the aquaculture industry, the factory aquaculture mode has received extensive attention due to its high efficiency and intensiveness. However, this mode also brings challenges in treating aquaculture tail water. The factory aquaculture tail water contains a large amount of pollutants such as residual bait, feces, ammonia nitrogen, nitrite, and nitrate. If directly discharged, it will cause serious pollution to the environment. Therefore, it is particularly important to develop effective tail water treatment methods.

[0003] The existing factory recirculating aquaculture mode usually adopts sedimentation treatment or vertical filter screens for preliminary filtration. Although sedimentation filtration is easy for solid-liquid separation, the time is too long, the sedimentation tank occupies a large area, which affects the filtration efficiency. In addition, static sedimentation is easily affected by the external environment, and solid-liquid re-mixing is likely to occur during drainage, affecting the filtration quality of the tail water. While the vertical filter screen has good filtration effect in the short term, in the long-term operation, impurities are easily attached to the filter screen and accumulate between the separated filter screens, requiring frequent shutdown for cleaning, wasting a large amount of labor and reducing the filtration efficiency. Biological treatment methods such as constructed wetlands and biological filters are also applied in tail water treatment, but there are some limitations. For example, constructed wetlands occupy a large area, and the treatment efficiency is greatly affected by seasons and climate; the biological filter has a poor removal effect on COD. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for treating factory aquaculture tail water to achieve efficient recovery of aquaculture tail water.

[0005] The present invention provides a method for treating factory aquaculture tail water, including the following steps: Introduce the aquaculture tail water into a sedimentation tank for sedimentation to obtain the sedimented tail water. The sedimentation tank is provided with a water retaining facility, and the sedimentation time is 1h to 3h; Introduce the sedimented tail water into an ecological purification tank for purification for 2h to 4h to obtain the tail water after primary ecological purification treatment; submerged plants, floating-leaved plants, and emergent plants are planted in the ecological purification tank, and silver carp, catfish, crucian carp, freshwater prawns, snails, and mussels are stocked; introduce the ecologically purified tail water into an aeration tank, and then perform disinfection treatment; the aeration tank is provided with a biofilm packing column installed by hanging, and microporous aeration heads are evenly distributed at the bottom of the tank. The density of the biofilm packing column is 5000 - 8000 roots / mu, and the density of the microporous aeration heads is 220 - 250 pieces / mu; the biofilm packing column is composed of packing and microorganisms. The packing is one or more of biochar, volcanic stone, and ceramsite, and the microorganisms are Spirulina, Bacillus subtilis, Bacillus licheniformis, and Micrococcus luteus.

[0006] Preferably, the volume ratio of the sedimentation tank, the ecological purification tank and the aeration tank is 200-300:350-450:900-1200; the depth of the sedimentation tank is 2.5 m-3.5 m, the depth of the ecological purification tank is 1.5 m-2.5 m, and the depth of the aeration tank is 1 m-2 m; preferably, the water retaining facility includes brushes and biological bins, which are arranged vertically along the water flow direction, and the intervals in the front, back, left and right directions are 30 cm-50 cm.

[0007] Preferably, the submerged plants include Vallisneria natans and Hydrilla verticillata, the floating-leaved plants include Nymphaea tetragona, and the emergent plants include Phragmites australis and Typha orientalis Presl; the planting area of the submerged plants accounts for 20% of the ecological purification tank, the planting area of the floating-leaved plants accounts for 20% of the ecological purification tank, and the planting area of the emergent plants accounts for 20% of the ecological purification tank.

[0008] Preferably, the stocking amount of silver carp is 50-100 tails / mu, the stocking amount of catfish is 30-50 tails / mu, the stocking amount of crucian carp is 100-200 tails / mu, the stocking amount of Macrobrachium nipponense is 10-20 kg / mu, the stocking amount of snails is 150-300 kg / mu, and the stocking amount of mussels is 40-50 kg / mu.

[0009] Preferably, the mass ratio of spirulina to the filler is 0.2-2:1; the mass ratio of Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus is 2-5:1-3:1-2; the total mass of Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus and the mass ratio of the filler is 0.01-0.02:1; the viable bacteria count per g of bacteria ≥ 5-10×10 8 . The present invention has no special limitation on the sources of Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus, and conventional commercially available products can be used.

[0010] Preferably, the distance between the top of the aeration head and the bottom of the biological packing column is 1 m.

[0011] Preferably, the biological packing column is of an annular structure, with a height of 1.5 m-2.5 m, an inner diameter of 5-8 cm and an outer diameter of 7-10 cm in the cross section.

[0012] Preferably, the specific surface area of the biological packing column is 2.5 mm 2 / g-4 mm 2 / g.

[0013] Preferably, the time for disinfection treatment is 30 min-60 min.

[0014] Advantages of the present invention: In the present invention, the tail water is first precipitated, which can effectively remove most of the suspended solids and large particulate impurities in the tail water, significantly reduce the turbidity of the water body, and create good conditions for subsequent ecological purification treatment; the water retaining facilities in the sedimentation tank can increase the flow path and residence time of the water flow, enabling the suspended solids to have more sufficient time to precipitate, improving the precipitation efficiency, and further enhancing the effect of water quality pretreatment. Through the preliminary treatment in the sedimentation tank, the present invention reduces the pollutant load entering the ecological purification tank, reduces the treatment pressure of the ecological purification tank, extends the service life of the ecological purification tank, and improves the operation efficiency and stability of the entire tail water treatment system.

[0015] Submerged plants, floating-leaved plants and emergent plants are planted in the ecological purification tank, which can form a multi-level ecological purification system; the stocked aquatic animals such as silver carp, catfish, crayfish, snails and mussels form a biological synergistic purification system with the plants. Submerged plants can absorb nutrients in the water and inhibit the overgrowth of algae. Floating-leaved plants can block sunlight, reduce water temperature and reduce the reproduction of algae; emergent plants can absorb pollutants through their roots and at the same time provide habitats for aquatic animals; fish such as silver carp and catfish feed on plankton, which can effectively control the number of plankton and reduce water eutrophication; benthic animals such as crayfish, snails and mussels further purify the water quality by feeding on the organic matter and algae in the bottom mud. At the same time, their activities can also promote the release and diffusion of pollutants in the bottom mud and improve the self-purification ability of the water body.

[0016] Biological packing columns are evenly distributed in the aeration tank. This kind of packing with a high specific surface area can provide a large number of attachment sites for microorganisms, thus significantly increasing the contact area between microorganisms and the water body. This is not only conducive to the adsorption and decomposition of organic matter and nutrients in the water by microorganisms, but also can improve the purification efficiency of the entire treatment system; the biological packing columns adopt an annular structure, and this structural design further optimizes the layout of the packing to ensure that the water flow can fully pass through the packing, thereby maximizing the contact efficiency.

[0017] The biological packing column is composed of one or more of biochar, volcanic stone, and ceramsite. These materials have good adsorption properties and biocompatibility. The microorganisms attached to the packing include Spirulina, Bacillus subtilis, Bacillus licheniformis, and Micrococcus luteus. These microorganisms form biofilms on the surface of the packing, which can efficiently decompose organic matter and nutrients in water; Spirulina can effectively remove inorganic nitrogen (such as ammonia nitrogen, nitrite, nitrate) and inorganic phosphorus (such as phosphate) in the tail water; after co-culturing Spirulina with Bacillus licheniformis, Bacillus subtilis, and Micrococcus luteus, a stable algal-bacterial symbiotic system can be formed in the water environment. This symbiotic system can effectively promote the growth of Spirulina and accelerate the removal of nitrogen and phosphorus in the aquaculture tail water; in addition, Spirulina also has a good enrichment effect on certain heavy metals. After co-culturing Micrococcus luteus with Bacillus licheniformis and Bacillus subtilis, the ecological purification effect can be further enhanced, effectively improving the removal rates of chemical oxygen demand (COD) and ammonia nitrogen (NH 4+ -N), nitrate nitrogen (NO 3 - -N) in the tail water and improving the degradation ability of refractory organic matter.

[0018] In the present invention, the microporous aeration heads are arranged at the bottom of the pond. A large number of bubbles generated by the microporous aeration heads are in full contact with the water body during the rising process, increasing the dissolved oxygen content in the water body. A high dissolved oxygen environment is beneficial to the metabolic activities of microorganisms, especially the functions of nitrifying bacteria and denitrifying bacteria. These microorganisms can convert ammonia nitrogen in the water into nitrate, and then convert nitrate into nitrogen gas and release it into the atmosphere through denitrification, thereby effectively removing nitrogen elements in the water; at the same time, the aeration process can also promote the oxidation and precipitation of phosphorus elements in the water body, further reducing the phosphorus content in the water body.

[0019] A distance of 1 m is maintained between the top of the aeration head and the bottom of the biological packing column. This design not only avoids the blockage of the aeration head by the packing, but also ensures that the bubbles can fully penetrate the packing layer, improving the aeration efficiency. The design of the aeration pond takes into account the uniform distribution of water flow and the cutting effect of bubbles, reducing the phenomena of water flow short-circuit and dead zones, and improving the stability and reliability of the entire system.

[0020] The present invention combines physical, biological, and chemical treatment means, can efficiently treat tail water in a short time, reduces the floor area and operating cost of treatment equipment, and has high economy and practicality. After being treated by the method of the present invention, the reuse rate of the tail water is not less than 80%, and the quality of the treated tail water can meet the national specified discharge standards. Detailed Embodiments

[0021] In order to further illustrate the present invention, the following describes in detail a method for treating factory aquaculture tail water provided by the present invention in combination with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0022] In the embodiments of the present invention, unless otherwise specified, the substances used are all conventional commercially available products.

[0023] Example 1 Set up a sedimentation tank: Brush and biological tanks are arranged vertically along the water flow direction, with a spacing of 50 cm in the front, back, left and right.

[0024] Introduce the aquaculture tail water into the sedimentation tank with a water retaining facility, and sediment for 2 h to obtain the sedimented tail water.

[0025] Introduce the sedimented tail water into the ecological purification pond. In the ecological purification pond, vallisneria accounting for 20% of the total area, water lilies accounting for 20% of the total area and calamus accounting for 20% of the total area are planted; 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of green shrimps, 200 kg of snails and 40 kg of mussels are put in per mu, and purified for 4 h to obtain the ecologically purified tail water.

[0026] Introduce the ecologically purified tail water into the aeration tank. The depth of the aeration tank is 4 m, in which uniformly distributed biological packing columns are provided, with a density of 6000 columns / mu, and uniformly distributed microporous aeration heads are provided at the bottom of the tank, with a density of 220 pieces / mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m; the biological packing column is of a ring structure, with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross section. The ring structure is filled with a packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with spirulina and a composite bactericide (Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus are mixed in a mass ratio of 2:1:1). The mass ratio of spirulina to the packing is 0.5:1, and the mass ratio of the composite bactericide to the packing is 0.01:1; After aeration for 3 h, disinfect with sodium hypochlorite for 60 min.

[0027] Example 2 Set up a sedimentation tank: Brush and biological tanks are arranged vertically along the water flow direction, with a spacing of 50 cm in the front, back, left and right.

[0028] Introduce the aquaculture tail water into the sedimentation tank with a water retaining facility, and sediment for 2 h to obtain the sedimented tail water.

[0029] Introduce the sedimented tail water into the ecological purification pond. In the ecological purification pond, vallisneria accounting for 20% of the total area, water lilies accounting for 20% of the total area and calamus accounting for 20% of the total area are planted; 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of green shrimps, 200 kg of snails and 40 kg of mussels are put in per mu, and purified for 4 h to obtain the ecologically purified tail water.

[0030] The ecologically purified tail water is introduced into the aeration tank. The depth of the aeration tank is 4 m, in which there are evenly distributed biological packing columns with a density of 6,000 columns per mu, and evenly distributed microporous aeration heads are arranged at the bottom of the tank with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m. The biological packing column is of a ring structure with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross-section. The ring structure is filled with packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with spirulina and a composite bactericide (Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus are mixed in a mass ratio of 4:3:2). The mass ratio of spirulina to the packing is 0.5:1, and the mass ratio of the composite bactericide to the packing is 0.01:1. After aeration for 3 h, it is disinfected with sodium hypochlorite for 60 min.

[0031] Example 3 A sedimentation tank is set up: brushes and biological bins are arranged vertically along the water flow direction with an interval of 50 cm in the front, back, left and right directions.

[0032] The aquaculture tail water is introduced into a sedimentation tank with a water retaining facility and sedimented for 2 h to obtain the sedimented tail water.

[0033] The sedimented tail water is introduced into an ecological purification tank, in which vallisneria accounting for 20% of the total area, water lilies accounting for 20% of the total area and calamus accounting for 20% of the total area are planted; 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of green shrimps, 200 kg of snails and 40 kg of mussels are put in per mu, and after purification for 4 h, the ecologically purified tail water is obtained.

[0034] The ecologically purified tail water is introduced into the aeration tank. The depth of the aeration tank is 4 m, in which there are evenly distributed biological packing columns with a density of 6,000 columns per mu, and evenly distributed microporous aeration heads are arranged at the bottom of the tank with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m. The biological packing column is of a ring structure with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross-section. The ring structure is filled with packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with spirulina and a composite bactericide (Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus are mixed in a mass ratio of 3:2:1). The mass ratio of spirulina to the packing is 0.5:1, and the mass ratio of the composite bactericide to the packing is 0.01:1. After aeration for 3 h, it is disinfected with sodium hypochlorite for 60 min.

[0035] Example 4 A sedimentation tank is set up: brushes and biological bins are arranged vertically along the water flow direction with an interval of 50 cm in the front, back, left and right directions.

[0036] The aquaculture tail water is introduced into a sedimentation tank with a water retaining facility and sedimented for 2 h to obtain the sedimented tail water.

[0037] The precipitated tail water is introduced into an ecological purification pond. In the ecological purification pond, vallisneria accounting for 20% of the total area, water lilies accounting for 20% of the total area, and calamus accounting for 20% of the total area are planted; 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of green shrimps, 200 kg of snails and 40 kg of mussels are put into each mu, and after 4 hours of purification, the ecologically purified tail water is obtained.

[0038] The ecologically purified tail water is introduced into an aeration tank. The aeration tank is 4 m deep, in which uniformly distributed biological packing columns are provided, with a density of 6000 columns per mu, and uniformly distributed microporous aeration heads are provided at the bottom of the tank, with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m; the biological packing column is of an annular structure, with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross section. The annular structure is filled with packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with spirulina and a composite bactericide (Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus are mixed in a mass ratio of 5:3:2), and the mass ratio of spirulina to the packing is 0.5:1, and the mass ratio of the composite bactericide to the packing is 0.01:1; after 3 hours of aeration, it is disinfected with sodium hypochlorite for 60 minutes.

[0039] Control Example 1 A sedimentation tank is set up: Brushes and biological bins are arranged vertically along the water flow direction, with an interval of 50 cm in the front, back, left and right.

[0040] The aquaculture tail water is introduced into a sedimentation tank with a water retaining facility, and after 2 hours of sedimentation, the precipitated tail water is obtained.

[0041] The precipitated tail water is introduced into an ecological purification pond. In the ecological purification pond, vallisneria accounting for 20% of the total area, water lilies accounting for 20% of the total area, and calamus accounting for 20% of the total area are planted; 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of green shrimps, 200 kg of snails and 40 kg of mussels are put into each mu, and after 4 hours of purification, the ecologically purified tail water is obtained.

[0042] The ecologically purified tail water is introduced into an aeration tank. The aeration tank is 4 m deep, in which uniformly distributed biological packing columns are provided, with a density of 6000 columns per mu, and uniformly distributed microporous aeration heads are provided at the bottom of the tank, with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m; the biological packing column is of an annular structure, with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross section. The annular structure is filled with packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with a composite bactericide (Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus are mixed in a mass ratio of 2:1:1), and the mass ratio of the composite bactericide to the packing is 0.01:1; after 3 hours of aeration, it is disinfected with sodium hypochlorite for 60 minutes.

[0043] Comparative Example 2 Set up a sedimentation tank: Brushes and biological tanks are arranged vertically along the water flow direction, with a spacing of 50 cm in the front, back, left, and right directions.

[0044] Introduce the aquaculture tail water into the sedimentation tank with a water retaining facility, and precipitate for 2 hours to obtain the precipitated tail water.

[0045] Introduce the precipitated tail water into the ecological purification pond. In the ecological purification pond, plant Vallisneria natans accounting for 20% of the total area, Nymphaea tetragona accounting for 20% of the total area, and Acorus calamus accounting for 20% of the total area; put 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of freshwater shrimps, 200 kg of snails, and 40 kg of mussels per mu, and purify for 4 hours to obtain the ecologically purified tail water.

[0046] Introduce the ecologically purified tail water into the aeration tank. The depth of the aeration tank is 4 m, in which uniformly distributed biological packing columns are provided, with a density of 6000 columns per mu, and uniformly distributed microporous aeration heads are provided at the bottom of the tank, with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m; the biological packing column is of a ring structure, with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross section. The ring structure is filled with a packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with Spirulina platensis and Micrococcus luteus. The mass ratio of Spirulina platensis to the packing is 0.5:1, and the mass ratio of Micrococcus luteus to the packing is 0.01:1; after aeration for 3 hours, disinfect with sodium hypochlorite for 60 minutes.

[0047] Comparative Example 3 Set up a sedimentation tank: Brushes and biological tanks are arranged vertically along the water flow direction, with a spacing of 50 cm in the front, back, left, and right directions.

[0048] Introduce the aquaculture tail water into the sedimentation tank with a water retaining facility, and precipitate for 2 hours to obtain the precipitated tail water.

[0049] Introduce the precipitated tail water into the ecological purification pond. In the ecological purification pond, put 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of freshwater shrimps, 200 kg of snails, and 40 kg of mussels per mu, and purify for 4 hours to obtain the ecologically purified tail water.

[0050] The tail water after ecological purification is introduced into the aeration tank. The depth of the aeration tank is 4 m, in which there are evenly distributed biological packing columns with a density of 6,000 columns per mu, and evenly distributed microporous aeration heads are arranged at the bottom of the tank with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m. The biological packing column is of a ring structure with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross-section. The ring structure is filled with packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with spirulina and Bacillus licheniformis, and the mass ratio of spirulina to the packing is 0.5:1, and the mass ratio of Bacillus licheniformis to the packing is 0.01:1. After aeration for 3 h, it is disinfected with sodium hypochlorite for 60 min.

[0051] Comparative Example 4 A sedimentation tank is set up: brushes and biological bins are arranged vertically along the water flow direction with an interval of 50 cm in the front, back, left and right directions.

[0052] The aquaculture tail water is introduced into a sedimentation tank with a water retaining facility and sedimentated for 2 h to obtain the sedimentated tail water.

[0053] The sedimentated tail water is introduced into an ecological purification pond, in which vallisneria accounting for 20% of the total area, water lilies accounting for 20% of the total area and calamus accounting for 20% of the total area are planted; 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of green shrimps, 200 kg of snails and 40 kg of mussels are put in per mu, and after purification for 4 h, the tail water after ecological purification is obtained.

[0054] The tail water after ecological purification is introduced into the aeration tank. The depth of the aeration tank is 4 m, in which there are evenly distributed biological packing columns with a density of 6,000 columns per mu, and evenly distributed microporous aeration heads are arranged at the bottom of the tank with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m. The biological packing column is of a ring structure with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross-section. The ring structure is filled with packing with a mass ratio of biochar, volcanic stone and ceramsite of 1:1:1. The packing is attached with spirulina and a composite bactericide (Bacillus subtilis and Bacillus licheniformis are mixed in a mass ratio of 2:1), and the mass ratio of spirulina to the packing is 0.5:1, and the mass ratio of the composite bactericide to the packing is 0.01:1. After aeration for 3 h, it is disinfected with sodium hypochlorite for 60 min.

[0055] Comparative Example 5 A sedimentation tank is set up: brushes and biological bins are arranged vertically along the water flow direction with an interval of 50 cm in the front, back, left and right directions.

[0056] The aquaculture tail water is introduced into a sedimentation tank with a water retaining facility and sedimentated for 2 h to obtain the sedimentated tail water.

[0057] Introduce the precipitated tail water into the ecological purification pond. Plant Vallisneria natans accounting for 20% of the total area, Nymphaea tetragona accounting for 20% of the total area, and Acorus calamus accounting for 20% of the total area in the ecological purification pond; put 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of freshwater shrimps, 200 kg of snails, and 40 kg of freshwater mussels per mu, and purify for 4 hours to obtain the ecologically purified tail water.

[0058] Introduce the ecologically purified tail water into the aeration tank. The aeration tank is 4 m deep, in which uniformly distributed biological packing columns are provided, with a density of 6000 columns per mu, and uniformly distributed microporous aeration heads are provided at the bottom of the tank, with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m; the biological packing column is of a ring structure, with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross section. The ring structure is filled with packing with a mass ratio of 1:1:1 of biochar, volcanic stone and ceramsite; after aeration for 3 hours, disinfect with sodium hypochlorite for 60 minutes.

[0059] Comparative Example 6 Set up a sedimentation tank: Vertically arrange brushes and biological bins along the water flow direction, with an interval of 50 cm in the front, back, left and right.

[0060] Introduce the aquaculture tail water into the sedimentation tank with a water retaining facility, and precipitate for 2 hours to obtain the precipitated tail water.

[0061] Introduce the precipitated tail water into the ecological purification pond. Plant Vallisneria natans accounting for 20% of the total area, Nymphaea tetragona accounting for 20% of the total area, and Acorus calamus accounting for 20% of the total area in the ecological purification pond; put 60 silver carps, 40 catfishes, 120 crucian carps, 15 kg of freshwater shrimps, 200 kg of snails, and 40 kg of freshwater mussels per mu, and purify for 4 hours to obtain the ecologically purified tail water.

[0062] Introduce the ecologically purified tail water into the aeration tank. The aeration tank is 4 m deep, in which uniformly distributed biological packing columns are provided, with a density of 6000 columns per mu, and uniformly distributed microporous aeration heads are provided at the bottom of the tank, with a density of 220 per mu. The distance between the top of the aeration head and the bottom of the biological packing column is 1 m; the biological packing column is of a ring structure, with a height of 2 m, an inner diameter of 5 cm and an outer diameter of 8 cm in the cross section. The ring structure is filled with packing with a mass ratio of 1:1:1 of biochar, volcanic stone and ceramsite, and Spirulina is attached to the packing, and the mass ratio of Spirulina to the packing is 0.5:1. After aeration for 3 hours, disinfect with sodium hypochlorite for 60 minutes.

[0063] Test Example 1 Take the tail water treated by the methods of Examples 1 to 4 and Comparative Examples 1 to 6 as samples respectively, and detect their nitrogen and phosphorus removal rates. The results are shown in Table 1.

[0064] Table 1 Nitrogen and phosphorus removal effects

[0065] As can be seen from Table 1, compared with Comparative Examples 1 to 6, Examples 1 to 4 have higher nitrogen and phosphorus removal rates, indicating that Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus have a certain synergistic effect. After mixing spirulina with Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus in the present invention, an algae-bacteria symbiotic system is formed, further improving the removal efficiency of nitrogen and phosphorus in the aquaculture tail water.

[0066] Test Example 2 The tail water treated by the methods of Examples 1 to 4 and Comparative Examples 1 to 6 was used as a sample respectively, and its COD removal rate and turbidity removal rate were detected. The results are shown in Table 2.

[0067] Table 2 Tail water treatment effect

[0068] As can be seen from Table 2, compared with Comparative Examples 1 to 6, Examples 1 to 4 have higher COD removal rates and turbidity removal rates. It can be seen that putting aquatic animals and plants in the ecological purification pond and coordinating their ratios in the present invention can effectively improve the purification efficiency.

[0069] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments without creative efforts based on these embodiments, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for treating tail water from factory farming, characterized in that: The following steps are involved: The aquaculture tail water is introduced into a sedimentation tank for sedimentation to obtain precipitated tail water, wherein the sedimentation tank contains a water retaining facility, and the sedimentation time is 1h to 3h; The tail water after sedimentation is introduced into the ecological purification pool for purification for 2h~4h to obtain ecologically purified tail water; submerged plants, floating-leaf plants and emergent plants are planted in the ecological purification pool, and silver carp, catfish, crucian carp, green shrimp, snails and river clams are stocked; The tail water after ecological purification is introduced into an aeration tank for aeration for 2h~5h, and then disinfected; the aeration tank is provided with evenly distributed biological filler columns, and evenly distributed microporous aeration heads are provided at the bottom of the tank, the density of the biological filler columns is 5000~8000 / mu, and the density of the microporous aeration heads is 220~250 / mu; the biological filler columns are composed of fillers and microorganisms, the fillers are one or more of biochar, volcanic rock and ceramsite, and the microorganisms are spirulina, Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus.

2. The method according to claim 1, characterized in that The volume ratio of the sedimentation tank, the ecological purification tank and the aeration tank is 200-300:350-450:900-1200; the depth of the sedimentation tank is 2.5m-3.5m, the depth of the ecological purification tank is 1.5m-2.5m, and the depth of the aeration tank is 3m-5m.

3. The method according to claim 1, characterized in that The submerged plants include Vallisneria and Hydrilla, the floating-leaf plants include Water Lily, and the emergent plants include Reed and Cattail.

4. The method according to claim 1, characterized in that The planting area of ​​the submerged plants accounts for 20% of the ecological purification pool, the planting area of ​​the floating-leaf plants accounts for 20% of the ecological purification pool, and the planting area of ​​the emergent plants accounts for 20% of the ecological purification pool.

5. The method according to claim 1, characterized in that The release amount of silver carp is 50 to 100 per mu, the release amount of catfish is 30 to 50 per mu, the release amount of crucian carp is 100 to 200 per mu, the release amount of green shrimp is 10 to 20 kg per mu, the release amount of snails is 150 to 300 kg per mu, and the release amount of clams is 40 to 50 kg per mu.

6. The method according to claim 1, characterized in that The mass ratio of the spirulina to the filler is 0.2-2:1; the mass ratio of the Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus is 2-5:1-3:1-2; and the mass ratio of the total mass of the Bacillus subtilis, Bacillus licheniformis and Micrococcus luteus to the filler is 0.01-0.02:

1.

7. The method according to claim 1, characterized in that The distance between the top of the aeration head and the bottom of the biological filler column is 1 m.

8. The method according to claim 1, characterized in that The biological filler column is an annular structure with a height of 1.5m to 2.5m, an inner diameter of a cross section of 5 to 8cm, and an outer diameter of 7 to 10cm.

9. The method according to claim 1, characterized in that: The specific surface area of ​​the biological filler column is 2.5 mm 2 / g~4mm 2 / g.

10. The method according to claim 1, characterized in that The disinfection treatment time is 30min~60min.

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