A wetland system for internal circulation purification of farmland drainage and aquaculture tail water and its construction method

Abstract

The present application relates to the technical field of water ecological restoration, and provides a wetland system for internal circulation purification of farmland drainage and aquaculture tail water and a construction method thereof, which synergistically couples the purification of farmland drainage and pond aquaculture tail water, constructs a wetland system mainly composed of drainage ecological channels, buffer ponds, and purification ponds, and combines farmland and aquaculture ponds to construct a multi-circulation purification system, which effectively solves the current problem of farmland drainage and aquaculture tail water directly discharging to pollute the surrounding river water bodies, and realizes efficient treatment of farmland drainage and aquaculture tail water. The present invention not only solves the two-way circulation reuse and efficient purification of farmland drainage and aquaculture tail water, but also forms a low-maintenance artificial wetland landscape, realizing the organic combination of water pollution treatment and ecological restoration.

Description

Technical Field

[0001] The present application belongs to the technical field of water ecological restoration, and specifically relates to a wetland system for farmland drainage and internal circulation purification of aquaculture tail water and a construction method thereof. Background Art

[0002] With the in-depth implementation of water pollution prevention and control work, the pollution control of industrial wastewater, domestic sewage and other aspects has achieved remarkable results. In contrast, the pollution of farmland drainage, which is extensive and large in scale, has become an important factor restricting the continuous improvement of the quality of the water ecological environment due to traditional production methods, lack of control technology, insufficient capital investment and weak management. In addition to farmland production, aquaculture is also an important part of the agricultural and rural economy. Since the 1990s, the aquaculture industry has entered a period of rapid development. While bringing good economic benefits, it has also caused damage to the water ecological environment to varying degrees, such as the current more common high-density farming method. According to traditional farming methods, a large amount of leftover bait and feces will be discharged into the water body, causing pollution. The pollution of aquaculture tailwater is becoming increasingly serious, which will not only lead to a decline in the quality and output of aquaculture products, but also cause serious pollution to the surrounding river water bodies due to the direct discharge of aquaculture tailwater.

[0003] In recent years, farmland drainage and aquaculture tailwater treatment have received more and more attention, and some related treatment and restoration work has been gradually carried out, and a series of technical standards have been accumulated in the purification and recycling of farmland drainage and the discharge of aquaculture tailwater. Some existing related technologies, such as patents such as publication numbers CN112062275A, CN111533364A, and CN112358053A, provide the construction of a system for intercepting, purifying, and reusing pollutants in farmland drainage; CN114642188A, CN112931370A, and CN112825811A provide a comprehensive treatment system for pond aquaculture tailwater.

[0004] The above-mentioned technologies have the following deficiencies: (1) Technical research and development is only carried out for the treatment of farmland drainage or pond aquaculture tailwater, and the two are not synergistically coupled; (2) The application of a single technology has high requirements for land occupation and cost, and the purification system function is relatively single; (3) The recycling and multi-stage purification of water resources are not fully considered. In addition, among the existing related technologies, taking the patent with publication number CN215559732U as an example, although a pond aquaculture tailwater and farmland planting recycling system is constructed, the system only aerates the aquaculture tailwater and cannot meet the requirements of efficient purification of farmland drainage and aquaculture tailwater. How to construct a wetland system for internal circulation purification of farmland drainage and aquaculture tailwater, promote the efficient purification and recycling of farmland drainage and aquaculture tailwater, thereby improving the efficiency of water resource utilization and improving the regional water environment quality, is a technical problem currently faced. Summary of the invention

[0005] The present application provides a wetland system for internal circulation purification of farmland drainage and aquaculture tail water and a construction method thereof, so as to solve the problems in the existing related technologies that a purification system is only constructed for a single farmland drainage or aquaculture tail water, or the combined system of the two is just a simple superposition of water purification facilities, and it is impossible to organically combine water pollution treatment and in-situ ecological restoration, and it is impossible to achieve both two-way circulation reuse and efficient purification of farmland drainage and aquaculture tail water, and to use various ecological restoration measures to form a low-maintenance wetland landscape.

[0006] In the first aspect of the present application, a wetland system for farmland drainage and internal circulation purification of aquaculture tail water is provided, comprising farmland, aquaculture pond, and a drainage ecological channel, a buffer pond and a purification pond connected to the farmland in sequence; the drainage ecological channel comprises a primary drainage ecological channel, a secondary drainage ecological channel and a tertiary drainage ecological channel connected in sequence; the farmland is connected to the primary drainage ecological channel; ecological infiltration dams are arranged between the primary drainage ecological channel and the secondary drainage ecological channel, and between the secondary drainage ecological channel and the tertiary drainage ecological channel; the tertiary drainage ecological channel is connected to the buffer pond through an overflow weir; the buffer pond is connected to the purification pond through an overflow sluice gate; the aquaculture pond is connected to the tertiary drainage ecological channel and the purification pond respectively; the ecological infiltration dam crosses the drainage channel. The water flow cross-section of the drainage ecological channel is prism-shaped by the superposition of several graded pebbles; the water level of the third-level drainage ecological channel on one side of the overflow weir is higher than the water level of the buffer pond on the other side, and the water flow above the top of the overflow weir flows into the buffer pond through the overflow weir; ground cover plants are planted on the slopes of the first-level drainage ecological channel, the second-level drainage ecological channel, the third-level drainage ecological channel, the buffer pond and the purification pond; emergent plants are planted at the bottom of the second-level drainage ecological channel; between the ground cover plants and the water bottom of the slopes of the third-level drainage ecological channel, the buffer pond and the purification pond, ecological bags arranged in a stepped shape along the slope are arranged, and emergent plants are planted on the ecological bags; submerged plants are planted at the bottom of the third-level drainage ecological channel and the bottom of the purification pond.

[0007] Optionally, several groups of ecological purification infiltration belts are arranged in the purification pond, each group of ecological purification infiltration belts spans across the two banks of the purification pond and divides the purification pond into several parallel areas, and the water flow in each area passes horizontally through the ecological purification infiltration belt to enter another area; the bottom of the ecological purification infiltration belt is connected to the bottom surface of the purification pond, the height is the same as the average depth of the purification pond, and the whole is long and narrow, including gabion stone cages and ecological fillers stacked and filled in the gabion stone cages.

[0008] Optionally, the first-level water drainage ecological channel is distributed along the periphery of the farmland plot, and its cross-section is an inverted trapezoid or an inverted triangle; the cross-section of the second-level water drainage ecological channel is an inverted trapezoid, and the lower base of the inverted trapezoid is 0.2-0.5m, the slope ratio is 1:2, and the channel depth is 0.5-1m; the cross-section of the tertiary water drainage ecological channel is an inverted trapezoid, and the lower base of the inverted trapezoid is 1-5m, the slope ratio is 1:2, and the channel depth is 1-2m; the maximum depth of the buffer pond is 3.5m, the average water depth is 2.5m, and the slope ratio is 1:3; the maximum depth of the purification pond is 2.5m, and the average water depth is 1.5m.

[0009] Optionally, the buffer pond and the purification pond are of an integrated structure to form an integrated pond body, and the integrated pond body is divided into two areas, the buffer pond and the purification pond, according to the order of water inflow through the overflow dam.

[0010] Optionally, a connecting hole is provided at the bottom of the overflow dam, so that the water in the purification pond can flow into the buffer pond through the connecting hole.

[0011] Optionally, the breeding pond is connected to the three-level water withdrawal ecological channel and the purification pond through a water pump and a pipeline respectively; the buffer pond is connected to the farmland through a water pump and a pipeline for water reuse in the farmland.

[0012] Optionally, the ecological filler in the gabion cage mesh is stacked to form a long wall shape, and the ecological filler includes one or more of boulders and pebbles.

[0013] Optionally, the ground cover plants include one or more of goosegrass, ryegrass, tall fescue, dandelion, alfalfa, and plantain; the emergent plants include one or more of wild rice stem, reed, yellow calamus, cattail, Cyperus rotundus, lily of the valley, and canna; the submerged plants include one or more of Malayan pondweed, comb-toothed pondweed, Vallisneria sinensis, Potamogeton crispus, and Hydrilla verticillata.

[0014] The second aspect of the present application also provides a method for constructing the above-mentioned wetland system for farmland drainage and internal circulation purification of aquaculture effluent, wherein the first-level drainage ecological channel is distributed along the periphery of the farmland plot and directly collects the farmland drainage, and then the water flows through the second-level drainage ecological channel and the third-level drainage ecological channel in turn, and enters the buffer pond and the purification pond; after the aquaculture effluent from the aquaculture pond is discharged into the third-level drainage ecological channel, it is processed in the buffer pond and the purification pond in turn; farmland water is taken from the buffer pond, and the aquaculture water of the aquaculture pond is taken from the purification pond.

[0015] Optionally, the water withdrawal ecological channel is obtained through in-situ transformation and construction of the original farmland drainage ditch; the buffer pond and purification pond are obtained through in-situ transformation and construction of the irrigation and drainage ditches and the withdrawal pond around the original farmland; the buffer pond and purification pond are constructed separately in the form of two separated pond bodies, or are constructed together in the form of two areas divided into a comprehensive pond body.

[0016] Compared with the prior art, the beneficial effects of this application are:

[0017] The wetland system for internal circulation purification of farmland drainage and aquaculture tail water provided in this application and its construction method are aimed at the actual need of efficient sewage treatment of farmland drainage and pond aquaculture tail water due to the lack of dedicated sites. The farmland drainage purification and pond aquaculture tail water purification are synergistically coupled to construct a multi-circulation purification system, including a three-level circulation purification and reuse system of "farmland → drainage ecological channel → buffer pond → farmland", "farmland → drainage ecological channel → buffer pond → purification pond → aquaculture pond → drainage ecological channel → buffer pond-farmland", and "aquaculture pond → drainage ecological channel → buffer pond → purification pond → aquaculture pond". It effectively solves the current problem of pollution of surrounding river water bodies caused by direct discharge of farmland drainage and aquaculture tail water, and realizes efficient treatment of farmland drainage and aquaculture tail water. The constructed circulating purification system can achieve an overall interception rate of 50%, 30% and 20% for chemical oxygen demand, ammonia nitrogen and total phosphorus, respectively, thereby meeting the needs of aquaculture water and discharge into rivers, improving the efficiency of water resource utilization, avoiding regional water pollution, saving land area and construction costs, and achieving synergistic enhancement of economic and ecological benefits.

[0018] Furthermore, in the wetland system of the present application, three levels of ecological drainage channels, drainage buffer ponds and purification ponds for farmland drainage are constructed. These diverse habitats can effectively respond to changes in plant habitats caused by seasonal changes in water levels. The construction of ecological infiltration dams, overflow weirs and infiltration belts has a significant effect on intercepting water pollutants, and can operate independently without human intervention, and basically requires no maintenance. It can be seen that the wetland system constructed in this application not only ensures the two-way recycling and efficient purification of farmland drainage and aquaculture tail water, but also forms a low-maintenance artificial wetland landscape, realizing the organic combination of water pollution treatment and ecological restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 This is a schematic diagram of the wetland system structure for farmland drainage and aquaculture tail water internal circulation purification according to an embodiment of the present application;

[0021] Figure 2 A schematic plan view of a wetland system for internal circulation purification of farmland drainage and aquaculture tail water according to an embodiment of the present application;

[0022] Figure 3 A schematic cross-sectional view of an overflow weir according to an embodiment of the present application;

[0023] Figure 4 This is a schematic cross-sectional view of a primary water withdrawal ecological channel according to an embodiment of the present application;

[0024] Figure 5 A schematic cross-sectional view of a secondary water withdrawal ecological channel according to an embodiment of the present application;

[0025] Figure 6 A schematic cross-sectional view of a three-level water withdrawal ecological channel according to an embodiment of the present application;

[0026] Figure 7 A schematic cross-sectional view of a buffer pond according to an embodiment of the present application;

[0027] Figure 8 A schematic cross-sectional view of a purification pond according to an embodiment of the present application;

[0028] Fig. 9 A schematic diagram of a purification pond according to an embodiment of the present application

[0029] Fig.10 This is a schematic elevation diagram of an ecological purification infiltration belt according to an embodiment of the present application;

[0030] Fig.11 This is a schematic elevation diagram of an ecological infiltration dam according to an embodiment of the present application;

[0031] Fig.12 This is a schematic plan view of the ecological infiltration dam according to an embodiment of the present application.

[0032] In the figure, 1- farmland, 2- drainage ecological channel, 21- first-level drainage ecological channel, 22- second-level drainage ecological channel, 23- tertiary drainage ecological channel, 231- ecological bag, 24- ecological infiltration dam, 3- buffer pond, 31- overflow weir, 4- purification pond, 41- overflow dam, 42- ecological purification infiltration belt, 421- gabion stone cage net, 422- ecological filler, 5- breeding pond, 6- ground cover plants, 7- emergent plants, 8- submerged plants. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is described in detail below with reference to the accompanying drawings and embodiments.

[0034] The wetland system for farmland drainage and aquaculture tail water internal circulation purification in this application is as follows Figure 1 and Figure 2As shown, it includes farmland 1, breeding pond 5, and drainage ecological channel 2, buffer pond 3 and purification pond 4 connected with the farmland in sequence; the drainage ecological channel 2 includes a primary drainage ecological channel 21, a secondary drainage ecological channel 22 and a tertiary drainage ecological channel 23 connected in sequence; the farmland 1 is connected with the primary drainage ecological channel 21; ecological infiltration dams 24 are arranged between the primary drainage ecological channel 21 and the secondary drainage ecological channel 22, and between the secondary drainage ecological channel 22 and the tertiary drainage ecological channel 23; the tertiary drainage ecological channel 23 is connected with the buffer pond 3 through an overflow weir 31; the buffer pond 3 and the purification pond 4 are connected through an overflow dam 41; the breeding pond 5 is connected with the tertiary drainage ecological channel 23 and the purification pond 4 respectively; as shown Fig.11 and Fig.12 As shown, the ecological infiltration dam 24 crosses the water flow section of the drainage ecological channel 2 and is formed into a prism shape by stacking a number of graded pebbles; Figure 3 As shown, the water level of the three-level water withdrawal ecological channel 23 on one side of the overflow weir 31 is higher than the water level of the buffer pond 3 on the other side, and the water flow above the overflow weir top flows into the buffer pond 3 through the overflow weir 31; Figures 4 to 8 As shown, ground cover plants 6 are planted on the slopes of the first-level water withdrawal ecological channel 21, the second-level water withdrawal ecological channel 22, the third-level water withdrawal ecological channel 23, the buffer pond 3 and the purification pond 4; emergent plants 7 are planted at the bottom of the second-level water withdrawal ecological channel 22; between the ground cover plants 6 and the bottom of the slopes of the tertiary water withdrawal ecological channel 23, the buffer pond 3 and the purification pond 4, ecological bags 231 arranged in a stepped shape along the slopes are provided, and emergent plants 7 are planted on the ecological bags 231; submerged plants 8 are planted at the bottom of the tertiary water withdrawal ecological channel 23 and the bottom of the purification pond 4.

[0035] Specifically, this application aims to address the practical problem that there is no effective site for efficient treatment of farmland drainage and pond aquaculture effluent, and synergistically couples the farmland drainage purification with the pond aquaculture effluent purification to construct a three-stage circulation purification and reuse system of "farmland → drainage ecological channel → buffer pond → farmland", "farmland → drainage ecological channel → buffer pond → purification pond → aquaculture pond → drainage ecological channel → buffer pond → farmland", and "aquaculture pond → drainage ecological channel → buffer pond → purification pond → aquaculture pond". It strengthens the efficient purification of farmland drainage and aquaculture effluent, improves the efficiency of water resource utilization, saves land and construction costs while ensuring economic benefits, and avoids regional water pollution.

[0036] In addition, this application constructs three levels of farmland drainage ecological channels, drainage buffer ponds and purification ponds. These diverse habitats can effectively respond to changes in plant habitats caused by seasonal changes in water levels. The construction of ecological infiltration dams, overflow weirs and infiltration belts has a significant effect on intercepting water pollutants, without human intervention and basically no maintenance. The circulating purification system can achieve interception rates of 50%, 30% and 20% or more for chemical oxygen demand, ammonia nitrogen and total phosphorus, meeting the needs of aquaculture water and discharge into rivers.

[0037] As a preference, Figure 2 and Figure 4 As shown, the primary drainage ecological channel 21 is distributed along the periphery of the farmland plot, and the cross section is in the shape of an inverted trapezoid or an inverted triangle; Figure 5 As shown, the cross section of the secondary drainage ecological channel 22 is inverted trapezoidal, and the lower base of the inverted trapezoid is 0.2-0.5m, the slope ratio is 1:2, and the channel depth is 0.5-1m; Figure 6 As shown, the cross section of the three-level drainage ecological channel 23 is inverted trapezoidal, and the lower base of the inverted trapezoid is 1 to 5 meters, the slope ratio is 1:2, and the channel depth is 1 to 2 meters;

[0038] Specifically, the first-level water withdrawal ecological channel directly collects the water withdrawn from the farmland. Its cross-section is an inverted triangle or an inverted trapezoid according to the current status of the farmland. The specific size is determined according to the actual environment on site. The slopes of the first-level water withdrawal ecological channel are generally planted with native land cover plants.

[0039] The secondary drainage ecological channel is used to collect the water from the primary drainage ecological channel. The secondary drainage ecological channel is generally set in an inverted trapezoidal shape, with a lower width of 0.2-0.5m, a slope ratio of 1:2, and a height of 0.5-1m. Native emergent plants are planted at the bottom of the channel, and native ground cover plants are planted on the slopes. An ecological infiltration dam is set at the entrance of the primary drainage ecological channel into the secondary drainage ecological channel.

[0040] The tertiary ecological channel is used to collect water from the secondary ecological channel. The tertiary ecological channel is set up in an inverted trapezoidal shape, with a lower width of about 1-5m, a slope ratio of 1:2, and a height of 1-2m. The slopes are protected by ecological bags, native submerged plants are planted at the bottom of the channel, and emergent plants are planted on the slopes. An ecological infiltration dam is generally set at the entrance of the secondary ecological channel into the tertiary ecological channel.

[0041] like Figure 7 As shown, in this embodiment, the buffer pond 3 is set at a maximum depth of 3.5m, an average water depth of about 2.5m, a slope ratio of 1:3, and the slope of the buffer pond 3 is protected by an ecological bag 231. The buffer pond 3 mainly collects farmland drainage and initial rainwater, and is also used for secondary irrigation and reuse of farmland water. Only a certain amount of emergent plants 7 are planted in the slope area. An overflow weir is generally set at the entrance of the three-level drainage ecological channel into the buffer pond.

[0042] The purification pond further regulates and purifies the farmland drainage and initial rainwater in the buffer pond and then uses them for fishery breeding. Figure 8 As shown, in this embodiment, the water depth in the purification pond 4 is 2.5m at its deepest point, the average effective water depth is 1.5m, the slope is protected by ecological bags, submerged plants 8 are planted in the purification pond, and emergent plants 7 are planted in the slope area. According to the needs of aquaculture water, several groups of green and environmentally friendly ecological purification infiltration belts are set in the purification pond.

[0043] As a preference, Fig. 9 As shown, each set of ecological purification infiltration belts 42 spans across both banks of the purification pond 4 and divides the purification pond 4 into a number of parallel areas. The water flow in each area transversely passes through the ecological purification infiltration belt 42 to enter another area; Fig.10 As shown, the bottom of the ecological purification infiltration zone 42 is connected to the bottom surface of the purification pond 4, and its height is the same as the average depth of the purification pond 4. The whole is in a long strip shape, including a gabion cage 421 and an ecological filler 422 stacked and filled in the gabion cage.

[0044] Specifically, the water flow in each area of ​​the purification pond can flow in a unidirectional manner in sequence, from the buffer pond water area of ​​the purification pond through the ecological purification infiltration belt to the next area, forming a unidirectional pollutant gradually purified and reduced parallel area; the buffer pond water can also enter from the middle area, and the water flow diffuses through other areas in the front and rear circumferential direction; the specific water flow arrangement of the purification pond can also be set in other ways according to the actual site conditions and location, which are not listed here. In addition, the ecological purification infiltration belt 42 adopts a gabion stone cage structure (in this embodiment, the gabion stone cage has a lower bottom length of 4m, an upper bottom length of 2m, a height of 1.5m, and a width of 0.5m), which is filled with resource-based application-type ecological fillers. Preferably, the ecological filler 422 in the gabion stone cage 421 is stacked to form a long wall shape, and the ecological filler 422 includes one or more of block stones and pebbles.

[0045] Preferably, a communication hole is provided at the bottom of the overflow dam 41 , so that the water in the purification pond can flow into the buffer pond 3 through the communication hole.

[0046] Specifically, the buffer pond 3 and the purification pond 4 are interconnected through the overflow dam 41. When the buffer pond 3 reaches the set water level, the water flows into the purification pond 4 through the overflow dam 41. A connecting hole is left at the bottom of the overflow dam 41, and the purification pond 4 can replenish water to the buffer pond 3 when farmland irrigation is needed.

[0047] Preferably, the breeding pond 5 is connected to the three-level water withdrawal ecological channel 23 and the purification pond 4 through a water pump and a pipeline respectively; the buffer pond 3 is connected to the farmland 1 through a water pump and a pipeline for water reuse in the farmland.

[0048] Specifically, the aquaculture pond uses a water pump to take water from the purification pond for fishery aquaculture, and the tail water of the aquaculture is discharged into the three-level water withdrawal ecological channel, and then enters the buffer pond after purification in the three-level ecological channel, and is reused for farmland irrigation or further purified in the purification pond. The water for farmland and aquaculture ponds can be reused by using facilities such as water pumps and water pipes, or existing ditches and rivers can be selected according to site conditions and location distribution.

[0049] Preferably, the ground cover plants 6 include one or more of goosegrass, ryegrass, tall fescue, dandelion, alfalfa, and plantain; the emergent plants 7 include one or more of wild rice stem, reed, yellow calamus, cattail, Cyperus rotundus, lily of the valley, and canna; the submerged plants 8 include one or more of Malayan pondweed, comb-toothed pondweed, Vallisneria sinensis, waterweed, and Hydrilla verticillata.

[0050] Specifically, the selection and planting of plants must follow the principle of localism, and choose from plants that are suitable for local climate and soil conditions, to form a green landscape with a variety of vegetation at different heights and rich habitats, while achieving the functions of water purification and landscape greening.

[0051] The present application also provides a method for constructing the above-mentioned wetland system for farmland drainage and internal circulation purification of aquaculture tail water. The first-level drainage ecological channel 21 is distributed along the periphery of the farmland 1 plot and directly collects the farmland drainage. Then the water flows through the second-level drainage ecological channel 22 and the third-level drainage ecological channel 23 in turn, and enters the buffer pond 3 and the purification pond 4; after the aquaculture tail water of the aquaculture pond 5 is discharged into the third-level drainage ecological channel 23, it is processed in the buffer pond 3 and the purification pond 4 in turn; the farmland water is taken from the buffer pond 3, and the aquaculture water of the aquaculture pond 5 is taken from the purification pond 4.

[0052] Specifically, the construction method of the present application includes the construction of a drainage ecological channel system, a buffer pond system and a purification pond system. In view of the relative dispersion, randomness, instantaneity and large volume of farmland drainage, the farmland drainage ditches are ecologically transformed to construct a total of three levels of drainage ecological channels. Furthermore, an ecological interception ditch can be formed to extend the hydraulic retention time and enhance the interception and purification effect of nitrogen and phosphorus in farmland drainage by adding efficient nitrogen and phosphorus absorbing plants, efficient nitrogen and phosphorus adsorption substrates, infiltration dams or overflow weirs. In view of the large amount of water and high content of suspended solids in farmland drainage and initial rainwater, this application constructs a drainage buffer pond system at the end of the three-level drainage ecological channel according to local conditions. In view of the pollution characteristics of farmland drainage and aquaculture tail water, an efficient purification pond system is constructed to ecologically purify the incoming water so that it meets the aquaculture water standards and the requirements for discharge into the river.

[0053] Preferably, the water withdrawal ecological channel 2 is obtained by in-situ reconstruction of the original farmland drainage ditch; the buffer pond 3 and purification pond 4 are obtained by in-situ reconstruction of the irrigation and drainage ditch and the de-stocking pond around the original farmland; the buffer pond 3 and purification pond 4 are constructed separately in the form of two separated pond bodies, or are combined and constructed in the form of two areas divided into two areas in a comprehensive pond body. Preferably, the buffer pond 3 and purification pond 4 are an integrated structure, forming a comprehensive pond body, and the overflow dam 41 is used to separate the comprehensive pond body into two areas, the buffer pond 3 and the purification pond 4, according to the order of water inflow.

[0054] Specifically, for buffer ponds, the construction of buffer ponds is carried out in combination with the regional precipitation indicators for many years to collect farmland runoff and initial rainwater. The area of ​​buffer ponds is generally 3-5m per mu of farmland. 3 The construction of buffer ponds should be rationally constructed according to the irrigation scale, terrain conditions, transportation and farming requirements, and it is advisable to utilize the original irrigation and drainage ditches, ponds and cellars for transformation.

[0055] For the purification pond, it is located at the end of the buffer pond, which further regulates and purifies the farmland retreat and initial rainwater, so as to achieve "return water without direct discharge". The purification pond should be transformed by using the surrounding retired ponds. Aquatic plants suitable for the local environment should be planted in the pond, and ecological floating islands should be set up in conjunction. The construction of the purification pond should be considered from the aspects of ecology, economy and material sources. If there are restrictions on land use and cost, the buffer pond can be built together with the purification pond.

[0056] It can be seen that the present application provides a wetland system for internal circulation and purification of farmland drainage and aquaculture tail water and a construction method thereof. An enhanced surface flow type artificial wetland is constructed between the farmland and the aquaculture pond as a buffer pond and a purification pond according to local conditions. The farmland tail water is introduced into the buffer pond and the purification pond in sequence through the ecological channel for purification, so that its various indicators meet the standards of fishery aquaculture. The farmland tail water that meets the standards after purification in the purification pond is introduced into the aquaculture pond for fishery aquaculture. The fishery aquaculture tail water is introduced into the ecological channel for purification treatment, and finally used for farmland irrigation or aquaculture recycling, thereby forming an internal circulation system of farmland-fish pond, realizing the two-way recycling and efficient purification of farmland drainage and aquaculture tail water, saving land and investment costs, improving the efficiency of water resource utilization, and effectively solving the current problem of farmland drainage and aquaculture tail water directly discharging and polluting the surrounding river water bodies.

[0057] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A wetland system for internal circulation and purification of farmland drainage and aquaculture tail water, characterized in that: It includes farmland, breeding pond, and ecological drainage channel, buffer pond and purification pond connected with the farmland in sequence; the buffer pond is connected with the farmland through a water pump and a pipeline for water reuse in the farmland; The water withdrawal ecological channel includes a first-level water withdrawal ecological channel, a second-level water withdrawal ecological channel and a third-level water withdrawal ecological channel which are connected in sequence; the farmland is connected to the first-level water withdrawal ecological channel; ecological infiltration dams are arranged between the first-level water withdrawal ecological channel and the second-level water withdrawal ecological channel, and between the second-level water withdrawal ecological channel and the third-level water withdrawal ecological channel; the third-level water withdrawal ecological channel is connected to the buffer pond through an overflow weir; the buffer pond is connected to the purification pond through an overflow sluice dam; the breeding pond is connected to the third-level water withdrawal ecological channel and the purification pond respectively; The ecological infiltration dam crosses the water flow section of the drainage ecological channel and is formed into a prism shape by stacking a number of graded pebbles; The water level of the three-level water withdrawal ecological channel on one side of the overflow weir is higher than the water level of the buffer pond on the other side, and the water flow above the top of the overflow weir flows into the buffer pond through the overflow weir; Ground cover plants are planted on the slopes of the first-level water retreat ecological channel, the second-level water retreat ecological channel, the third-level water retreat ecological channel, the buffer pond and the purification pond; emergent plants are planted at the bottom of the second-level water retreat ecological channel; between the ground cover plants and the water bottom of the slopes of the tertiary water retreat ecological channel, the buffer pond and the purification pond, ecological bags arranged in a stepped shape along the slopes are arranged, and emergent plants are planted on the ecological bags; submerged plants are planted at the bottom of the tertiary water retreat ecological channel and the bottom of the purification pond.

2. The wetland system according to claim 1, characterized in that: A plurality of ecological purification infiltration belts are arranged in the purification pond, each of which spans across both banks of the purification pond and divides the purification pond into a plurality of parallel areas, and the water flow in each area passes horizontally through the ecological purification infiltration belt into another area; The bottom of the ecological purification infiltration zone is connected to the bottom of the purification pond. Its height is the same as the average depth of the purification pond. It is long and narrow in shape, including gabion gabions and ecological fillers stacked and filled in the gabion gabions.

3. The wetland system according to claim 1, characterized in that: The first-level drainage ecological channel is distributed along the periphery of the farmland plots, and its cross section is in the shape of an inverted trapezoid or an inverted triangle; The cross section of the secondary drainage ecological channel is in an inverted trapezoidal shape, and the lower base of the inverted trapezoid is 0.2-0.5m, the slope ratio is 1:2, and the channel depth is 0.5-1m; The cross section of the three-level drainage ecological channel is in the shape of an inverted trapezoid, and the lower base of the inverted trapezoid is 1-5m, the slope ratio is 1:2, and the channel depth is 1-2m; The maximum depth of the buffer pond is 3.5m, the average water depth is 2.5m, and the slope ratio is 1:3; The maximum depth of the purification pond is 2.5m, and the average water depth is 1.5m.

4. The wetland system according to claim 1, characterized in that: The buffer pond and the purification pond are integrated structures to form a comprehensive pond body, and the comprehensive pond body is divided into two areas, the buffer pond and the purification pond, according to the order of water inflow through the overflow dam.

5. The wetland system according to claim 1, characterized in that: A communicating hole is arranged at the bottom of the overflow dam, so that the water in the purification pond can flow into the buffer pond through the communicating hole.

6. The wetland system according to claim 2, characterized in that: The ecological fillers in the gabion cage net are stacked to form a long wall shape, and the ecological fillers include one or more of boulders and pebbles.

7. The wetland system according to claim 1, characterized in that: The ground cover plants include one or more of goosegrass, ryegrass, tall fescue, dandelion, alfalfa, and plantain; The emergent plants include one or more of wild rice stem, reed, yellow calamus, cattail, Cyperus rotundus, lily of the valley, and canna; The submerged plants include one or more of Potamogeton malayi, Potamogeton comb-tooth, Vallisneria salsa, Potamogeton crispus, and Hydrilla verticillata.

8. The method for constructing a wetland system for farmland drainage and aquaculture tail water internal circulation purification according to any one of claims 1 to 7, characterized in that: The first-level water withdrawal ecological channel is distributed along the periphery of the farmland and directly collects the water withdrawal from the farmland. The water then flows through the second-level water withdrawal ecological channel and the third-level water withdrawal ecological channel in turn, and enters the buffer pond and the purification pond; the aquaculture effluent from the breeding pond is discharged into the third-level water withdrawal ecological channel, and then is treated in the buffer pond and the purification pond in turn; the water for farmland is taken from the buffer pond, and the aquaculture water for the breeding pond is taken from the purification pond.

9. The method for constructing a wetland system according to claim 8, characterized in that: The water withdrawal ecological channel is obtained by in-situ transformation and construction of the original farmland drainage ditch.

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