CN102358660B - Constructed wetland based system and method for recycling factory-like seawater culture discharged water - Google Patents

Abstract

The present invention discloses a system and method for recycling the drainage water from factory-scale seawater aquaculture based on artificial wetlands. The system and method connect two levels of artificial wetlands in series to treat the drainage water from seawater aquaculture, and recycle the sewage and sludge after harmless treatment. The drainage water from aquaculture is first pre-treated in a sedimentation tank and then enters a primary surface flow and a secondary upward vertical flow artificial wetland. After purification, it enters a reservoir and is reused. The sludge enters a sludge collection tank from the sedimentation tank and is used to grow salt-tolerant vegetables after biological composting. At the same time, the backwashing principle is used to restore the matrix blockage of the artificial wetland from time to time. Compared with the existing seawater aquaculture drainage treatment method, the present invention enhances the effect of nitrogen removal and phosphorus removal, and has low investment and operating costs. It has the characteristics of high efficiency, ecology, environmental protection, and economy, and is easy to promote and apply.

Description

System and method for recycling external drainage of industrial mariculture based on artificial wetland

technical field

The invention relates to a method for treating the external drainage of aquaculture, in particular to a system and method for treating the external drainage of mariculture by using artificial wetlands.

Background technique

In the past 20 years, my country's aquaculture industry has developed rapidly. According to statistics, my country's aquaculture production reached 35.97 million tons in 2006, accounting for 68% of my country's total fishery production and more than 70% of the world's total aquaculture production. It is currently the only country where aquaculture production exceeds fishing production. At present, China's industrial aquaculture water body has reached 5 million m ² , and it is expected that there will be a greater development in the future. Therefore, due to the continuous expansion of aquaculture scale, the deepening of intensification, and the lagging of environmental protection measures, the discharge of aquaculture external drainage not only leads to the destruction of the external environment, but also directly affects the safety of the aquaculture water body's own environment. At present, there are many treatment methods for mariculture external effluent. Physical methods include precipitation, adsorption, filtration, magnetic separation, foam separation, ultraviolet irradiation, etc.; chemical methods include flocculation, neutralization, complexation, chemical disinfection, etc., biological methods include adding light and bacteria, plant filters, activated sludge and biofilm. However, a single physical, chemical and biological method or a simple combination of several methods can no longer meet the needs of high-density factory farming, and there is an urgent need for a comprehensive water treatment method that integrates physics, chemistry and biology.

As a comprehensive treatment method, artificial wetland purification technology has shown good application prospects in the field of wastewater treatment. Theoretical research on sewage treatment in constructed wetlands began in 1953 at the MaxPlank Institute in Germany. In 1972, Seidel and Kichuth jointly proposed the root zone theory, which marked that constructed wetlands officially entered the field of water pollution control as a new type of sewage treatment technology. Since then, the artificial wetland water purification technology has been continuously improved, and has been widely used in Europe, the United States, Canada, Japan and other places in the 1980s and 1990s. At present, artificial wetland technology is more widely used. According to incomplete statistics, as of 2006, there were more than 10,000 artificial wetlands in Europe, nearly 20,000 artificial wetlands in North America, and more and more artificial wetlands in Asia, Australia, and Latin America. The wetland treatment system was built and put into use (Wang Shihe, 2007). The research on sewage treatment technology of constructed wetlands in my country began during the "Seventh Five-Year Plan" period. In 1990, the South China Environmental Protection Institute of the State Environmental Protection Administration built the Bainikeng Constructed Wetland in Shenzhen to process 3100m ³ of sewage per day, which can be regarded as the first real practice. Although the research on artificial wetland water purification technology started late in my country, it has developed rapidly. At present, the artificial wetland water purification technology has made important progress in the following aspects: (1) The application objects are constantly expanding. At first, constructed wetlands were mainly used for urban domestic sewage, and later they were gradually applied to the secondary treatment of various industrial wastewaters such as textiles, papermaking, food, electroplating, petrochemicals, and special types of wastewater, such as landfill leachate, storm runoff, etc. (2) The design scale is constantly expanding. The artificial wetland treatment system for prawn farming wastewater established by David et al. (2002) on the coast of the Gulf of Mexico covers an area of 7.7ha, with a daily wastewater treatment capacity of 13600m ³ . China's Beijing Olympic Park artificial wetland covers an area of 60,000 m ² , with a daily processing capacity of 30,000 m ³ . (3) The water purification effect is continuously improved. Summerfelts et al. (1999) used constructed wetlands to remove 96% of total suspended solids in aquaculture water, and 82-93% of Kjeldahl nitrogen. Liu et al. (2007) used constructed wetlands to purify heavy metals, and the removal rates of Cd, Pb, and Zn were all above 90%. The research of Molleda et al. (2008) showed that the removal rate of pathogenic microorganisms in constructed wetlands was 97.0-100%. Wen Yue et al. (2007) used horizontal subsurface flow constructed wetlands to treat organic matter in sewage, and the COD of the system effluent was less than 30mg/L.

Although artificial wetland technology provides the possibility for the treatment of mariculture effluent, there are still the following key technologies to be solved: (1) It is necessary to establish a salt-tolerant artificial wetland treatment system, including the selection and cultivation of salt-tolerant plants and microorganisms . (2) It is necessary to strengthen the effect of nitrogen and phosphorus removal in constructed wetlands, especially the advanced treatment of nitrogen and phosphorus at low concentrations. (3) Prevention and recovery measures of constructed wetland substrate clogging.

Therefore, the present invention is proposed in view of the current status of the external drainage and water purification technology of industrial mariculture, and in combination with the problems existing in the application of the constructed wetland technology.

Contents of the invention

The purpose of the present invention is to provide a system and method for recycling external drainage of industrial mariculture with good water purification effect, low investment and operating costs, simple and convenient operation, and unification of economic benefits, social benefits and ecological benefits; And through technological invention and transformation, it overcomes its weak salt tolerance, poor nitrogen and phosphorus removal effect, and easy clogging of the matrix.

The technical scheme of the present invention is as follows: a factory-based mariculture external drainage recycling system based on artificial wetlands, including a sedimentation tank connected to the drainage system of the cultivation workshop, and a drop aeration step is provided between the cultivation workshop and the sedimentation tank, The sedimentation tank is connected to the first-level surface flow artificial wetland through the drainage pipeline, and the first-level surface flow artificial wetland is connected to the bottom of the second-level vertical upward flow artificial wetland, so that the external drainage treated by the first-level surface flow artificial wetland enters the second-level vertical flow from the bottom. Upstream artificial wetland, the secondary vertical upstream artificial wetland is connected to the reservoir, and the reservoir is connected to the return water system of the breeding workshop through the canal; The sedimentation tank is connected to the sludge collection tank through the sludge discharge pipe, and the sludge collection tank is connected to the biocomposting treatment tank.

Further, as above-mentioned a kind of artificial wetland-based industrial mariculture external drainage recycling system, wherein, the matrix materials filled in the secondary vertical upflow artificial wetland are respectively 20cm gravel layer and 20cm zeolite layer from bottom to top. layer, 20cm blast furnace slag layer, 10cm medium gravel layer.

Furthermore, the above-mentioned a kind of artificial wetland-based industrial mariculture external drainage recycling system, wherein, the gravel particle size of the gravel layer is 5-8 cm, and the zeolite particle size of the zeolite layer is 3 cm. The blast furnace slag particle size of the blast furnace slag layer is 1-3 cm, and the medium gravel particle size of the medium gravel layer is 0.5-1 cm.

Further, the above-mentioned one kind of industrial mariculture external drainage recycling system based on constructed wetlands, wherein, the slopes of the first-level surface flow artificial wetland and the second-level vertical upward flow artificial wetland are both 0.3% to 2% .

Furthermore, a kind of industrialized mariculture external drainage recycling system based on constructed wetlands as described above, wherein, the first-level surface flow artificial wetland and the second-level vertical upward flow artificial wetland are planted with domesticated salt-tolerant plants , including one or more of reed, cattail, ricegrass, and Spartina alterniflora.

Further, the above-mentioned a kind of artificial wetland-based industrial mariculture external drainage recycling system, wherein, the diameter of the mud discharge pipe is 160mm-250mm, and the mud discharge pipe and the sedimentation tank of the secondary vertical upward flow artificial wetland The mud discharge pipes are connected in series, and are respectively 3 rows of mud outlets with a diameter of 20mm and a spacing of 100mm are left on the upper left, upper and upper right of the mud discharge pipe.

Further, the above-mentioned artificial wetland-based industrial mariculture external drainage recycling system also includes a vegetable planting area, where one or more of salt-tolerant vegetables Suaeda salsa, tomato, celery, and pepper are planted.

A method for recycling the external drainage of industrial mariculture based on artificial wetlands. The external drainage of aquaculture is discharged from the cultivation workshop, and then flows freely into the sedimentation tank after being aerated by falling water aeration steps under the action of gravity; Enter the first-level surface flow artificial wetland and the second-level vertical upward flow artificial wetland; after purification, it enters the reservoir and introduces it to the breeding workshop through the water channel for reuse; the settled suspended particulate matter enters through the sludge discharge pipe under the pressure of the water The sludge collection tank is transferred to the bio-composting treatment tank after re-sedimentation and dehydration, and is oxidized and fermented to make organic fertilizer for use in vegetable planting areas.

Further, the above-mentioned constructed wetland-based industrial mariculture drainage recycling method, wherein domesticated salt-tolerant microorganisms are added to the primary surface flow constructed wetland and the secondary vertical upward flow constructed wetland.

Further, the above-mentioned method for recycling waste water from industrial mariculture based on constructed wetlands, wherein the mud snails are cultivated in sedimentation tanks.

Compared with the prior art, the present invention has the following advantages:

(1) Efficient. It can effectively remove suspended matter, COD, nitrogen, phosphorus and other pollutants, especially compared with a single surface flow constructed wetland or a vertical flow constructed wetland, it has enhanced the effect of nitrogen and phosphorus removal.

(2) Economy. The investment cost of this technical project is low, no power consumption is required during operation, and maintenance costs are basically not required. Each square meter of constructed wetland can realize the recycling of 300 cubic meters of water every year, and the annual cost can be saved by more than 1,000 yuan.

(3) Environmental protection. This technology treats and recycles the external drainage of aquaculture, and realizes complete "zero discharge".

(4) Slow down and restore blockage. Intermittent water feeding is used to slow down matrix clogging, and backwashing process is used to restore matrix clogging.

(5) Ecology. Constructed wetland plants not only play a role in purifying water bodies, but also have certain greening and ornamental value. At the same time, it can be used as raw material for feed or organic fertilizer.

Description of drawings

Fig. 1 is a process flow chart of the recycling process of the external drainage of the industrial mariculture based on the artificial wetland;

Fig. 2 is a plan view of the external drainage recycling system of industrial mariculture based on constructed wetlands;

Figure 3 is a section view of the secondary vertical upflow constructed wetland;

Figure 4 is a top view of the secondary vertical upflow artificial wetland and the sedimentation tank discharge pipe;

Figure 5 is a sectional view of the mud discharge pipe.

In the figure: 1-breeding workshop; 2-drop water aeration steps; 3-sedimentation tank; 4-first-level surface flow artificial wetland; 5-secondary vertical upward flow artificial wetland; 6-reservoir; 7-water channel; 8-sludge collection tank; 9-biological composting tank; 10-vegetable cultivation area; 11-valve; 12-water pump; 13-drain pipe; 14-water inlet; 15-gravel; 16-zeolite; 17-high rate slag; 18-medium gravel; 19-water outlet; 20-reed; 21-drain outlet.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, a system for recycling external drainage of artificial mariculture based on artificial wetlands provided by the present invention is designed according to the topography and terrain, including aquaculture workshops, sedimentation tanks, primary surface flow artificial wetlands, secondary Constructed wetlands with vertical upward flow, storage tanks, sludge collection tanks, biocomposting treatment tanks and vegetable planting areas, etc., among which sedimentation tanks, first-level surface flow artificial wetlands, second-level vertical upward flow artificial wetlands, and storage tanks are connected in series It forms a recycling system for external drainage with the breeding workshop; the secondary vertical upflow artificial wetland, sedimentation tank, biocomposting treatment tank and vegetable planting area are connected in series to form a recycling system for excess sludge.

The external drainage of aquaculture is discharged from the aquaculture workshop, and flows freely into the sedimentation tank after being aerated by falling water and aeration steps under the action of gravity; after the suspended particulate matter is removed by sedimentation, it enters the first-level surface flow artificial wetland and the second-level vertical upward flow artificial wetland; After purification treatment, it enters the storage tank and is introduced into the breeding workshop for reuse through the water channel; the settled suspended particulate matter enters the sludge collection tank through the sludge discharge pipe under the pressure of the water, and is transferred to the biocomposting treatment after re-sedimentation and dehydration Ponds, which are oxidized and fermented to make organic fertilizers and used in vegetable planting areas.

The system structure of the present invention is composed as shown in Figure 2, including a sedimentation tank 3 connected to the drainage system of the cultivation workshop 1, a drop water aeration step 2 is provided between the cultivation workshop 1 and the sedimentation tank 3, and the sedimentation tank 3 is drained The pipeline is connected to the primary surface flow constructed wetland 4, and the primary surface flow constructed wetland 4 is connected to the bottom of the secondary vertical upward flow constructed wetland 5, so that the external drainage treated by the primary surface flow constructed wetland 4 enters the secondary vertical flow from the bottom. The upstream constructed wetland 5, the secondary vertical upstream constructed wetland 5 is connected to the reservoir 6, and the reservoir 6 is connected to the return water system of the breeding workshop 1 through the canal 7; the secondary vertical upstream constructed wetland 5 It is also connected with the sedimentation tank 3 through the sludge discharge pipe 13, and the sedimentation tank 3 is connected with the sludge collection tank 8 through the sludge discharge pipe, and the sludge collection tank 8 is connected with the biological composting treatment tank 9, and after oxidation and fermentation, the organic fertilizer is made into the vegetable planting District 10 is used. The functions and structural features of each component of the above system are as follows:

Breeding workshop 1: used for factory mariculture.

Sedimentation tank 3: It can realize the separation of cement and water discharged from mariculture, and remove most of the suspended particles and organic matter; filter-feeding mud snails are cultivated in the sedimentation tank, and the pipeline for sludge discharge is laid and the sludge collection tank and the secondary vertical Constructed wetlands are connected.

First-level surface flow constructed wetland 4: The bottom of the first-level surface flow constructed wetland is soil matrix, which is not filled with any other matrix materials, and domesticated salt-tolerant plants are planted on it, one of reed, cattail, Spartina, and Spartina alterniflora Several kinds.

Second-level vertical upflow constructed wetland 5: The matrix materials filled in the second-level vertical upflow constructed wetland are, from bottom to top, gravel (5-8cm) with a thickness of 20cm, zeolite (3-5cm) with a thickness of 20cm, and zeolite (3-5cm) with a thickness of 20cm blast furnace slag (1-3cm), medium gravel (0.5-1cm) with a thickness of 10cm. Domesticated salt-tolerant plants are planted on it, one or more of reeds, cattails, ricegrass, and Spartina alterniflora.

Reservoir 6: used to store the treated aquaculture effluent.

Sludge collection tank 8: Separation of mud and water can be realized.

Biological compost treatment pool 9: The sludge is oxidized and fermented into organic fertilizer by the biological compost treatment pool.

Vegetable planting area 10: Realize the recycling of organic fertilizers, and plant one or more of salt-tolerant vegetables Suaeda salsa, tomato, celery, and pepper.

The present invention will be described in detail below in conjunction with specific embodiments.

Example

As shown in Figure 2, the industrial mariculture external drainage recycling system based on artificial wetlands includes a sedimentation tank 3 connected to the drainage system of the breeding workshop 1, and a drop aeration is provided between the breeding workshop 1 and the sedimentation tank 3 Step 2, cultivating mud snails in sedimentation tank 3. The sedimentation tank 3 is connected to the first-level surface flow artificial wetland 4 through the drainage pipeline, the first-level surface flow artificial wetland 4 is connected to the bottom of the second-level vertical upward flow artificial wetland 5, and the first-level surface flow artificial wetland 4 is connected to the second-level vertical upward flow artificial wetland. The slope of the wetland 5 is 0.3% to 2% (referring to every 100 meters of horizontal distance, the vertical direction rises or falls by 0.3 to 2 meters), so that the external drainage treated by the first-level surface flow artificial wetland 4 enters the second-level vertical upward flow from the bottom Constructed wetland 5. Domesticated salt-tolerant plants are planted on the first-level surface flow constructed wetland 4 and the second-level vertical upflow constructed wetland 5, including one or more of reeds, cattails, Spartina, and Spartina alterniflora. The microorganisms in the first-level surface flow constructed wetland 4 and the second-level vertical upflow constructed wetland 5 are derived from the salt-tolerant microorganisms that reproduce naturally in the system on the one hand, and on the other hand from the added domesticated salt-tolerant microorganisms. The secondary vertical upflow artificial wetland 5 is connected to the reservoir 6, and the reservoir 6 is connected to the return water system of the breeding workshop 1 through the canal 7. The secondary vertical upflow constructed wetland 5 is also connected to the sedimentation tank 3 through the sludge discharge pipe 13, the sedimentation tank 3 is connected to the sludge collection tank 8 through the sludge discharge pipe, and the sludge collection tank 8 is connected to the biological composting treatment tank 9. After being oxidized and fermented to make organic fertilizer, it is used in the vegetable planting area 10, and one or more of salt-tolerant vegetables Suaeda salsa, tomato, celery, and pepper are planted in the vegetable planting area.

As shown in Figure 3, the matrix materials filled in the secondary vertical upflow constructed wetland are, from bottom to top, a gravel layer 15 with a thickness of 20 cm, a zeolite layer 16 with a thickness of 20 cm, a blast furnace slag layer 17 with a thickness of 20 cm, and a thickness of 20 cm. 10cm medium gravel layer 18. The gravel particle diameter of gravel layer 15 is 5～8cm, and the zeolite particle diameter of described zeolite layer 16 is 3～5cm, and the blast furnace slag particle diameter of described blast furnace slag layer 17 is 1～3cm, and described medium gravel layer 18 medium gravel particle size is 0.5 ~ 1cm. Reeds 20 are planted on the wetland, and the water outlet 19 of the wetland is above the middle gravel layer 18 . A mud discharge pipe 13 is provided at the bottom of the gravel layer 15 . The diameter of the mud discharge pipe 13 is 160mm-250mm.

As shown in Figure 4, the mud discharge pipe 13 at the bottom of the secondary vertical upflow artificial wetland 5 is connected in series with the mud discharge pipe 13 at the bottom of the sedimentation tank 3, and the two sets of mud discharge pipes 13 are respectively in the shape of shapes set. A valve 11 is arranged on the mud discharge pipeline connected in series. The two sets of mud discharge pipes 13 are separately controlled by two valves 11, and the mud is discharged from time to time. As shown in FIG. 5 , there are three rows of mud discharge outlets 21 with a diameter of 20 mm and an interval of 100 mm at the upper left, upper and upper right of the mud discharge pipe 13 .

The external drainage of mariculture is discharged from the breeding workshop 1, and then freely flows into the sedimentation tank 3 after falling water aeration and oxygenation under the action of gravity to realize the separation of mud and water; the external drainage enters the first-level surface flow artificial wetland 4 after being absorbed by salt-tolerant plants and matrix adsorption and microbial degradation for first-level treatment; the external drainage treated by the first-level surface flow constructed wetland 4 enters the second-level vertical upflow constructed wetland 5 through matrix filtration, adsorption, plant absorption, and microbial degradation for advanced treatment; the treated Water flows into the reservoir 6; the water in the reservoir can be reused to the breeding workshop 1 by the water pump 12.

The remaining sludge produced in the sedimentation tank 3 can be discharged into the sludge collection tank 6 from time to time through the sludge discharge pipe 13 at the bottom, and then transferred to the biocomposting treatment tank 9 after re-sedimentation and dehydration, where it is oxidized and fermented to make organic fertilizer Used in vegetable growing area 10. A mud discharge pipe 13 is installed at the bottom of the secondary vertical upflow constructed wetland 5 and is connected to the sedimentation tank 4, and the mud is discharged irregularly through the principle of backwashing.

This system can effectively remove pollutants such as suspended solids, COD, nitrogen, and phosphorus, and the removal rates of nitrogen and phosphorus are as high as 88% and 90% respectively.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (1)

1. a kind of industrialized mariculture external drainage recycling system based on artificial wetland, it is characterized in that: comprise the sedimentation tank (3) that is connected with the drainage system of cultivation workshop (1), cultivation workshop (1) and sedimentation tank ( 3) Falling water aeration steps (2) are provided in between, the sedimentation tank (3) is connected to the first-level surface flow artificial wetland (4) through the drainage pipeline, and the first-level surface flow artificial wetland (4) is connected to the second-level vertical upward flow The bottom of the constructed wetland (5) is connected so that the external drainage treated by the primary surface flow constructed wetland (4) enters the secondary vertical upward flow constructed wetland (5) from the bottom, and the secondary vertical upward flow constructed wetland (5) is connected to the storage The pond (6) is connected, and the reservoir (6) is connected with the backwater system of the cultivation workshop (1) through the water channel (7); it also includes a vegetable planting area (10) for planting salt-tolerant vegetables Suaeda salsa, tomato, and celery , one or more of peppers; the secondary vertical upflow artificial wetland (5) is also connected with the sedimentation tank (3) through the mud discharge pipe (13), and the sedimentation tank (3) is connected with the sewage through the mud discharge pipe Mud collection pond (8), sludge collection pond (8) connects biological compost treatment pond (9), and the matrix material of described secondary vertical upflow constructed wetland (5) is respectively 20cm gravel layer from bottom to top ( 15), 20cm zeolite layer (16), 20cm blast furnace slag layer (17), 10cm medium gravel layer (18); on the first-order surface flow artificial wetland (4) and the second-order vertical upward flow artificial wetland (5) Planting domesticated salt-tolerant plants, including one or more of reeds, cattails, Spartina, and Spartina alterniflora; the gravel particle size of the gravel layer (15) is 5-8 cm, and the zeolite layer The zeolite particle diameter of (16) is 3～5cm, the blast furnace slag particle diameter of described blast furnace slag layer (17) is 1～3cm, the medium gravel particle diameter of described medium gravel layer (18) is 0.5～1cm; The slopes of the first level surface flow constructed wetland (4) and the second level vertical upflow constructed wetland (5) are both 0.3% to 2%; the diameter of the mud discharge pipe (13) is 160mm to 250mm, and the second level The mud discharge pipes of the vertically upstream constructed wetland (5) are connected in series with the mud discharge pipes of the sedimentation tank (3), and are respectively The shape setting of; Leave 3 rows of diameters at the top left, top and top right of the mud discharge pipe (13) to be 20mm, and the spacing is the mud discharge port (21) of 100mm.