A micro-sedimentation tank system for the end of farmland ditches and its method

Abstract

The present application belongs to the technical field of farmland non-point source wastewater collection and purification, and particularly relates to a micro sedimentation tank system for the end of a farmland ditch and a method thereof. The micro sedimentation tank system for the end of a farmland ditch comprises an outer body contour and 1-5 layers of inner flow guide walls. The outer body contour is provided with a water inlet hole. The innermost layer of the inner flow guide walls is provided with an outflow extension pipe. The outflow extension pipe extends from the innermost layer of the inner flow guide walls to the outside of the outer body contour. The present application provides a micro sedimentation tank system for the end of a farmland ditch and a method thereof, which can strengthen the collection and treatment capacity of rural domestic sewage, improve the interception and treatment capacity of farmland non-point source pollution, reduce the treatment load of subsequent measures, and can be used for the end of a farmland ditch according to the characteristics of scattered and widely distributed rural pollution and farmland pollution, and can be changed in structure according to actual conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of farmland non-point source wastewater collection and purification, and particularly relates to a micro sedimentation tank system for the end of a farmland ditch and a method thereof. BACKGROUND

[0002] Prior art:

[0003] Sand traps with various complex structures are mostly used in water supply plant structures and sewage treatment plant structures, and have the characteristics of large pool body and complex structure, and have strong purification effect in water treatment, but these structures are mostly used in urban areas with population aggregation, and are rarely used in rural areas due to high investment, small benefits and other conditions. With the successive release of policies to accelerate the development of rural modernization, the continuous improvement of rural water facilities and farmland water conservancy facilities makes the water treatment and water collection technology in rural areas need to develop rapidly.

[0004] At present, farmland non-point source wastewater collection and purification technology mainly focuses on two aspects: one is to transform soil and concrete ditches into various structure ecological ditches for interception and purification, and the other is to build storage ponds similar structures at the end of the farmland ditch for purification. Ecological transformation of the ditch structure can strengthen the interception capacity of the ditch to some extent, but the farmland wastewater shows uneven flow state according to local climate conditions, which is not conducive to the growth of plants in the ecological ditch when the water quantity is small, and the hydraulic retention time in the ecological ditch is short when the water quantity is large, which will reduce the interception and purification capacity to some extent, and finally a large amount of nitrogen and phosphorus will flow into rivers and lakes. If a storage pond is built at the end of the ecological ditch, the above problems can be effectively solved, but it also causes the problem of land resource contradiction.

[0005] Difficulty and significance of solving the above technical problems:

[0006] Therefore, based on these problems, it is of important practical value to provide a micro sedimentation tank system for the end of a farmland ditch and a method thereof, which can strengthen the collection and treatment capacity of rural domestic wastewater, improve the interception and treatment capacity of farmland non-point source pollution, reduce the treatment load of subsequent measures, and have multiple functions and can make simple structural changes according to actual conditions. SUMMARY

[0007] The present application aims to provide a micro sedimentation tank system for the end of a farmland ditch and a method thereof, which can strengthen the collection and treatment capacity of rural domestic wastewater, improve the interception and treatment capacity of farmland non-point source pollution, reduce the treatment load of subsequent measures, and have multiple functions and can make simple structural changes according to actual conditions.

[0008] The technical scheme adopted by the embodiments of the present application to solve the technical problems in the prior art is as follows:

[0009] A micro sedimentation tank system for the end of a farmland ditch, comprising an outer body contour and 1-5 layers of inner layer flow guide walls, wherein the outer body contour is provided with a water inlet hole, the inner layer flow guide wall in the innermost layer is provided with an outflow extension pipe extending from the inside of the inner layer flow guide wall in the innermost layer to the outside of the outer body contour;

[0010] Each layer of the inner layer flow guide wall is provided with a water outlet hole, and the water outlet hole of each layer of the inner layer flow guide wall gradually decreases from the outside to the inside;

[0011] The space between the outer body contour and the inner layer flow guide wall in the outermost layer and the space between the inner layer flow guide walls are a bottom plane in the middle of the wall, and the bottom plane in the middle of the wall comprises a slope with a slope of 1:(4-7);

[0012] The tail end of the slope is a capture well with a depth of 0.2-0.5 m, the capture well is located between the outer body contour and the inner layer flow guide wall in the outermost layer or between two adjacent layers of the inner layer flow guide walls, and the width of the capture well is equal to the width of the bottom plane, the slope and the capture well are referred to as a slope type capture well, and a filter material partition wall is arranged downstream of the capture well.

[0013] The embodiments of the present application can also adopt the following technical scheme:

[0014] In the micro sedimentation tank system for the end of a farmland ditch, further, the outer body contour is a cuboid, a square, a cylinder or a column with an elliptical cross section, and the shape of the outer body contour and the inner layer flow guide wall is the same.

[0015] The cross section of the outer body contour can be square, rectangular, circular or elliptical, the square and rectangular types are convenient to manufacture and can be selected according to the limitation of the terrain, and compared with the square and rectangular types, the circular and elliptical types are beneficial to reducing the hydraulic loss and can be used in projects with high requirements for hydraulic loss.

[0016] In the micro sedimentation tank system for the end of a farmland ditch, further, when the outer body contour is a cuboid or a square, the capture well is square in shape and is located at the corner of the outer body contour or the inner layer flow guide wall, and the filter material partition wall is arranged at the place with the maximum hydraulic impact load;

[0017] When the outer body contour is a cylinder or a column with an elliptical cross section, the capture well is located at 2 / 3 of the bottom plane of each layer in the direction of water flow.

[0018] In the micro-sedimentation tank system for the end of farmland ditch, further, the outer body profile has a diameter of 1-5 m and a height of 1-5 m, and the material of the outer body profile and the inner layer flow guide wall is reinforced concrete structure or corrosion-proof PVC structure; when the outer body profile is the reinforced concrete structure, the thickness of the outer body profile is 5-20 cm; and when the outer body profile is the corrosion-proof PVC structure, the thickness of the outer body profile is 0.5-1.5 cm.

[0019] The reinforced concrete outer body profile has a thickness of 5-20 cm, which is suitable for the condition of deep burying caused by large water quantity and strong water flow impact; and the PVC structure outer body profile has a thickness of 0.5-1.5 cm, which is suitable for the condition of shallow burying.

[0020] In the micro-sedimentation tank system for the end of farmland ditch, further, when the outer body profile adopts the reinforced concrete structure, the drain holes are provided with multi-layer staggered distribution of grid nets; and when the outer body profile adopts the corrosion-proof PVC structure, the drain holes are provided with one layer of grid net.

[0021] When the outer body profile adopts the reinforced concrete structure, the wall has a certain thickness, and the multi-layer staggered distribution of grid nets is arranged at the position of the drain holes, so that the water flow is ensured to pass through, and the particles and sol are maximally intercepted; when the outer body profile adopts the corrosion-proof PVC structure, only one layer of filter grid is needed to be arranged due to the thin wall thickness, but the volume occupied by the wall thickness is reduced, so compared with the reinforced concrete structure, one more layer of inner layer flow guide wall can be arranged, and one more sedimentation cycle can be increased to strengthen the sedimentation effect.

[0022] In the micro-sedimentation tank system for the end of farmland ditch, further, the number of the drain holes is 1-3, and the drain holes of each layer of the inner layer flow guide wall are distributed on the same wall, and the drain holes of the adjacent two layers of the inner layer flow guide wall are staggered arranged; the drain holes on the nth layer of the inner layer flow guide wall are arranged according to the (n-1)th layer of the inner layer flow guide wall, i.e. the drain holes of the nth layer of the inner layer flow guide wall are distributed at the position after the water flow passes through the (n-1)th layer of the inner layer flow guide wall for half a cycle.

[0023] The drain holes on the adjacent two layers of the flow guide wall are oppositely distributed, so that the water flow entering the micro-sedimentation tank can at least walk through half the circumference before entering the next layer, so that the sedimentation time of the water flow is fully ensured.

[0024] The grid nets with the same aperture are installed on the drain holes of each layer of the inner layer flow guide wall, but the aperture of the grid net installed on the drain holes of the nth layer of the flow guide wall is smaller than the aperture of the grid net installed on the drain holes of the (n-1)th layer of the flow guide wall.

[0025] In the micro-sedimentation tank system for the end of farmland ditch, further, the inner layer diversion walls are gradually lowered in elevation from outside to inside, and the height difference between the adjacent two layers of inner layer diversion walls is 20-60 cm;

[0026] The height of the filter material partition wall is 1 / 4-1 / 2 of the height of the outer body contour or the outer layer of the adjacent two layers of inner layer diversion walls;

[0027] The water outlet hole is 10-15 cm lower than the upper edge of the inner layer diversion wall where the water outlet hole is located.

[0028] In order to prevent the water discharge of the farmland from exceeding the water discharge of the water outlet hole of the sand trap when the rainfall is large, the water will overflow the water outlet hole, and then flow into the next layer of diversion wall from the top of the outer layer diversion wall, so that the function of the sand trap can be exerted even when the water quantity is large.

[0029] In the micro-sedimentation tank system for the end of farmland ditch, further, the outer body contour is provided with an overflow port which is at least 10 cm lower than the upper edge of the outer body contour and higher than the water inlet hole.

[0030] When the water quantity reaches the maximum capacity of the micro-sedimentation tank, the micro-sedimentation tank is full of water, and the water can directly overflow into the river through the overflow port instead of overflowing from the top of the outer body contour of the micro-sedimentation tank and spreading around the micro-sedimentation tank.

[0031] In the micro-sedimentation tank system for the end of farmland ditch, further, the top of the outflow extension pipe is 10-20 cm lower than the water outlet hole of the inner layer diversion wall of the innermost layer.

[0032] A construction method of a micro-sedimentation tank system for the end of farmland ditch, the construction method of the micro-sedimentation tank system for the end of farmland ditch comprises the following steps:

[0033] Step 1: excavate a foundation pit at the end of the ditch, build an outer body contour and inner layer diversion walls from outside to inside in the foundation pit, or place the outer body contour and the inner layer diversion walls which have been prefabricated in the foundation pit, open a water inlet hole on the outer body contour, and set an overflow port opposite to the water inlet hole;

[0034] Step 2: set the slope of the bottom plane in the middle of the inner layer diversion walls, and set the capture well and the filter material retaining wall;

[0035] Step 3: set one end of the outflow extension pipe inside the inner layer diversion wall of the innermost layer, and extend the other end of the outflow extension pipe to the outside of the outer body contour.

[0036] The one or more technical solutions provided in the embodiments have at least the following beneficial effects:

[0037] 1. The micro sedimentation tank of the present application can extend the hydraulic retention time of farmland runoff to 3 times of that of a traditional sedimentation tank of the same size by arranging a multi-layer surrounding flow guide wall and a drain hole in a limited land area. Based on sufficient free settling time, the particles are settled in the capture well from top, middle and bottom layers by arranging filter material partition wall and a sloping bottom plane. In addition, the floating materials on the surface of the water body are removed by the multiple interception of the grid net, so that the contradiction between land resource shortage and ecological improvement is solved.

[0038] 2. The micro sedimentation tank of the present application has strong interception and purification effect on suspended particles. The water quality is continuously improved from the outer layer to the inner layer, and the removal rate of particle suspended impurities can reach 98% after entering the innermost layer. At the same time, the water entering the inner layer can be pumped into farmland for reuse irrigation, realizing resource reuse in small farmland area.

[0039] 3. The arrangement of the surrounding flow guide wall and the filter material partition wall of the micro sedimentation tank of the present application strengthens water quality purification and also affects water flow power. However, the water power is sufficiently strengthened by the gradual height reduction of the multi-layer surrounding flow guide wall from the outer layer to the inner layer, so that the water power is strengthened and the water power dead angle is prevented.

[0040] 4. The micro sedimentation tank of the present application has two forms of reinforced concrete and PVC structure. The reinforced concrete structure is the same as the traditional sedimentation tank material and construction method, and is suitable for use when the excavation is deep. The PVC structure is more convenient to install, can greatly reduce the construction period, and the inner flow guide wall is relatively thin. More inner flow guide walls can be arranged within a reasonable range, and the whole structure can be flexibly selected according to the actual situation.

[0041] 5. The micro sedimentation tank of the present application is based on the present situation of rural sewage discharge technology and the condition that there are many ditches in the areas where farmland water conservancy facilities are relatively developed. The land saving principle is followed, and the original local distributed ditches and other conditions are fully utilized to develop a micro sedimentation tank for the end of farmland ditch, which has very important significance for the prevention and control of farmland non-point source pollution.

[0042] 6. The micro sedimentation tank of the present application solves the problem that the farmland non-point source pollution is dispersed, distributed widely, and difficult to form effective interception measures in the region, and then directly discharged into the nearby rivers and lakes to cause pollution. The micro sedimentation tank can quickly and effectively intercept large particles and nitrogen and phosphorus in farmland runoff, so as to realize the ecological development of regional farmland environment.

[0043] 7、The application is constructed at the end of farmland ditch, can extend the hydraulic residence time, strengthen the interception and purification capacity on the basis of small land resources, and provides a new thought for the construction of ecological farmland. BRIEF DESCRIPTION OF DRAWINGS

[0044] The technical solutions of the embodiments of the present application will be further described in detail below with reference to the drawings, but it should be known that these drawings are only designed for the purpose of explanation, thus not as the limitation of the scope of the present application. In addition, unless specifically indicated, these drawings are only intended to conceptually illustrate the structural configuration described herein, and not necessarily drawn in proportion.

[0045] FIG. 1 is a schematic diagram of the water flow direction of the micro sedimentation tank; Figure 1 FIG. 2 is a top view of the structure of the micro sedimentation tank;

[0046] FIG. 3 is a schematic diagram of the water flow direction of the circular micro sedimentation tank; Figure 2 FIG. 4 is a top view of the structure of the circular micro sedimentation tank;

[0047] Figure 3 FIG. 5 is a left view of the structure section of the micro sedimentation tank A-A;

[0048] FIG. 6 is a left view of the structure section of the micro sedimentation tank B-B; Figure 4 FIG. 7 is a left view of the structure section of the micro sedimentation tank C-C;

[0049] Figure 5 FIG. 8 is a right view of the structure section of the micro sedimentation tank D-D;

[0050] FIG. 9 is a right view of the structure section of the micro sedimentation tank E-E; Figure 6 FIG. 10 is a right view of the structure section of the micro sedimentation tank F-F;

[0051] Figure 7 FIG. 11 is a right view of the structure section of the micro sedimentation tank J-J;

[0052] FIG. 12 is a bottom side view of the structure section of the micro sedimentation tank H-H; Figure 8 FIG. 13 is a bottom side view of the structure section of the micro sedimentation tank I-I;

[0053] Figure 9 FIG. 14 is a bottom side view of the structure section of the micro sedimentation tank I-I;

[0054] FIG. 15 is a bottom side view of the structure section of the micro sedimentation tank I-I; Figure 10 FIG. 16 is a bottom side view of the structure section of the micro sedimentation tank I-I;

[0055] Figure 11 FIG. 17 is a bottom side view of the structure section of the micro sedimentation tank I-I;

[0056] FIG. 18 is a bottom side view of the structure section of the micro sedimentation tank I-I; Figure 12 FIG. 19 is a bottom side view of the structure section of the micro sedimentation tank I-I;

[0057] Figure 13 FIG. 20 is a bottom side view of the structure section of the micro sedimentation tank I-I;

[0058] FIG. 21 is a bottom side view of the structure section of the micro sedimentation tank I-I; Figure 14 ​​​​​​Miniature sedimentation tank J-J structure profile bottom side view.

[0059] In the figure:

[0060] 1, the outer body contour, 2, the inner layer flow guide wall, 3, the drain hole, 4, the inclined capture well, 5, the filter material partition wall, 6, the outflow extension pipe, 7, the water inlet hole, 8, the grid, 9, the capture well, 10, the bottom plane, 11, the overflow port. DETAILED DESCRIPTION

[0061] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings and specific embodiments of the specification.

[0062] Example 1

[0063] This embodiment includes the outer body contour 1, the inner layer flow guide wall 2, the drain hole 3, the inclined capture well 4, the filter material partition wall 5, and the outflow extension pipe 6. The miniature sedimentation tank is arranged at the end of the ditch, and the farmland runoff is collected into the miniature sedimentation tank at the end of the ditch through the ditch. Through the special structure of the miniature sedimentation tank, large particles and nitrogen and phosphorus substances can be quickly intercepted, and then discharged into the river.

[0064] The outer body contour 1: The material shape and size of the outer body contour 1 are determined according to the actual application situation. The material can be selected from permanent reinforced concrete structure and portable anti-corrosion PVC structure. The shape can be made into a circle, an ellipse, a cuboid, a square, and other shapes. The size is mainly small and medium-sized, with a diameter of 1-5 m and a height of 1-5 m.

[0065] Among them, the reinforced concrete structure has a certain thickness of 5-20 cm, and the structure is relatively heavy. The anti-corrosion PVC structure has a smaller thickness of 0.5-1.5 cm, and the structure is relatively light.

[0066] The inner layer flow guide wall 2: The material and shape of the inner layer flow guide wall 2 follow the shape and material of the outer body contour 1, keeping the inside and outside consistent. The inner layer flow guide wall 2 can be provided with 1-5 layers according to the distribution of the amount of pollutants flowing out, with the elevation of each layer decreasing from outside to inside, and the height difference between adjacent flow guide walls being 20-60 cm. Each layer of flow guide wall is provided with 1-3 drain holes. The drain holes on the nth layer of flow guide wall are arranged according to the (n-1)th layer of flow guide wall, and the drain holes on the nth layer of flow guide wall are distributed at a position after the water flows through the (n-1)th layer of flow guide wall for half a circle.

[0067] The drain hole 3: The drain hole 3 is installed with grid nets of different hole diameters, that is, the same grid net is installed on the drain hole of each layer of the inner layer flow guide wall 2, but the hole diameter of the grid net installed on the drain hole of the nth layer of flow guide wall is smaller than that of the grid net installed on the drain hole of the (n-1)th layer of flow guide wall.

[0068] Inclined capture well 4: the front end of the inclined capture well, that is, the bottom plane 10 in the middle of the wall, is a slope with a slope of 1:(4-7), and the tail end of the slope is a capture well 9 with a depth of 0.2-0.5 m.

[0069] Filter material partition wall 5: the filter material partition wall 5 is located immediately downstream of the inclined capture well, in the form of a retaining wall column, and has the functions of stabilizing water flow and quickly sinking large-particle impurities and other substances in the capture well, the height of the filter material partition wall 5 is 1 / 4-1 / 2 of the height of the outer contour 1 or the inner guide wall 2 located in the outer layer of the adjacent two layers of inner guide walls 2, and is further preferably 25 cm-2.5 m, and if it is too high, it will affect the water flow power.

[0070] Outflow extension pipe 6: the outflow extension pipe 6 is extended from the inner guide wall to the external river channel through the outer contour, and is arranged at a height of 10-20 cm lower than the water discharge hole 10 of the inner guide wall, so as to ensure that the water flowing in from the water discharge hole is discharged after a certain degree of sedimentation, and if the arrangement height of the outflow extension pipe is equal to or higher than the water discharge hole, the direct discharge and backflow of the water flowing in from the water discharge hole will occur.

[0071] Example 2

[0072] On the basis of example one, the outer contour of the micro sedimentation tank is divided into two types of reinforced concrete material and PVC material micro sedimentation tank according to the manufacturing material, the reinforced concrete structure can adopt two ways of prefabrication and on-site pouring, and the PVC structure adopts the prefabrication way of the prefabrication factory.

[0073] There is a water inlet hole 7 on the outer contour 1 for connecting the outlet of the ditch, the size of the water inlet hole is set according to the size of the on-site ditch and the size of the water quantity, and the water inlet hole 7 is arranged with double-track vertical intelligent gates for controlling the water level of the ditch entering the micro sedimentation tank. The thickness of the reinforced concrete outer contour is 5-20 cm, which is suitable for the condition of deep burial depth caused by large water quantity and strong water flow impact force, and the thickness of the outer contour of the PVC structure is 0.5-1.5 cm, which is suitable for the condition of shallow burial depth. The cross section of the outer contour can be set as square, rectangular, circular and elliptical, and the square and rectangular types are convenient to manufacture and can be selected according to the limitation of the terrain, and the circular and elliptical types are beneficial to reducing the hydraulic loss compared with the square and rectangular types, and can be adopted for projects with high requirements for hydraulic loss. The overall size of the outer contour of the micro sedimentation tank is not more than 5 m in diameter and not more than 5 m in height.

[0074] The inner flow guide wall 2 of the micro sedimentation tank plays a role of guiding the water entering the micro sedimentation tank, and the water flow residence time can be effectively prolonged in the effective area through the flow guide, which can be up to 3 times compared with the prolonged time of the traditional sedimentation tank with the same size. The inner flow guide wall can be divided into 1-5 layers according to the design size of the micro sedimentation tank, and the more the number of layers is, the stronger the pollutant removal capacity is, and the better the effluent water quality is. The inner flow guide wall is respectively provided with 1-3 water outlets, the water outlets are distributed on the same wall, the water outlets on the upper adjacent two layers of the flow guide wall are oppositely distributed, which can ensure that the water flow entering the micro sedimentation tank at least walks through half the circumference before entering the next layer, thereby fully ensuring the sedimentation time of the water flow. The heights of the flow guide walls are different, and the inner flow guide wall is 20-60 cm lower than the outer flow guide wall. The height of each layer gradually decreases from the outer layer to the inner layer, which can enable the water flow to enter the next layer through the top overflow of the flow guide wall when the water flow and flow rate are very large. If the heights are set to be the same, the size of the water outlet capacity only depends on the size of the water outlet and a great pressure is generated on the inner flow guide wall.

[0075] When the micro sedimentation tank adopts a reinforced concrete structure, a plurality of staggered distribution of grid nets are arranged at the position of the water outlet, which can intercept the particles and sol particles to the maximum extent while ensuring the water flow. When the micro sedimentation tank adopts a PVC structure, only one layer of filter grid needs to be arranged due to the thin wall thickness, but one more layer of inner flow guide wall can be arranged compared with the reinforced concrete structure due to the reduced volume occupied by the wall thickness, which can increase one more sedimentation cycle and thereby strengthen the sedimentation effect.

[0076] The inclined capture well 4 of the micro sedimentation tank is divided into two parts of the capture well 9 and the bottom plane 10 in the wall body. If the micro sedimentation tank is square or rectangular, the capture well is located at the corner between the adjacent two layers of flow guide walls, and the corner is selected according to the principle of being far away from the water inlet of the layer and the water outlet of the adjacent lower layer. The shape of the capture well is set to be square, and the width is the spacing between the adjacent flow guide walls. If the micro sedimentation tank is circular, the capture well is located at 1 / 3 of the circumference, and the position is selected according to the same principle. The shape of the capture well is set to be a shape conforming to the circular radian, which can ensure that the size of the capture well can completely cover the cross section between the adjacent flow guide walls. The bottom plane refers to the bottom surface in front of the capture well, and the ground is set to be a slope with a slope of 1: (4-7), which is beneficial to the substances deposited in front of the capture well being finally washed into the capture well under the impact of the water flow in the bottom layer.

[0077] The filter material partition wall 5 of the micro sedimentation tank is arranged immediately behind the capture well, the height of the filter material partition wall is set to 1 / 4-1 / 2 of the height of the outer body contour, the height is preferably 25 cm-2.5 m, the length and width are equal and equal to the interval between adjacent guide walls. The length and width are equal to the interval between adjacent guide walls (i.e., the length and width are equal and equal to the interval between adjacent guide walls); the filter material uses materials such as pebbles, gravel, broken stones, volcanic rocks, and ceramsite, the filter material layer is filled in layers, the upper layer mainly uses filter materials with larger porosities such as pebbles, ceramsite, and volcanic rocks, and the lower layer mainly uses filter materials with smaller porosities such as broken stones and gravel, the filter material is fixed in the form of a steel wire mesh cage, and the mesh cage aperture is smaller than the minimum aperture of the filter material.

[0078] The outflow extension pipe 6 of the micro sedimentation tank is arranged in the innermost layer of the guide wall, the top of the pipe is 10-20 cm lower than the opposite water outlet hole of the innermost layer of the guide wall; the material of the extension pipe is PVC with light weight.

[0079] The overflow port 11 of the micro sedimentation tank is arranged at the uppermost part of the outer body contour, which is 10 cm lower than the wall height and higher than the water inlet hole 7, so as to ensure rapid drainage when the rainfall is large.

[0080] Example 3

[0081] This example adopts a reinforced concrete structure implementation:

[0082] This example includes an outer body contour, an inner layer of guide walls, water outlet holes, inclined capture wells, filter material partition walls, and outflow extension pipes. First, a foundation pit with a length, width, and height of 5 m*5 m*5 m is excavated at the end of the ditch, and a 15 cm thick outer body contour 1 of the micro sedimentation tank is built in the foundation pit. When building the outer body contour 1, the water inlet hole 7 is ensured to be equal in length and width and equal in bottom elevation to the end of the existing ditch, a double-track gate is arranged outside the water inlet hole 7 to control the flow into the micro sedimentation tank, and an overflow port 11 is arranged opposite the water inlet hole 7 of the outer contour 1, with a length* width of 50 cm*10 cm.

[0083] Then build the first layer of inner guide wall 2, the thickness of the inner guide wall is the same as the thickness of the outer body contour, leave 3 water discharge holes on the first layer of inner guide wall, the length and width of the water discharge hole are both 30 cm, set multiple layers of filter grating at the position of the water discharge hole, and the grating aperture is set to 1-1.5 cm, then build the second layer of inner guide wall 2, the thickness of the second layer of inner guide wall is 15 cm, leave 2 water discharge holes on the second layer of inner guide wall, the length and width of the water discharge hole are both 20 cm, set multiple layers of filter grating at the position of the water discharge hole, and the grating aperture is set to 0.8-1 cm, then build the third layer of inner guide wall 2, the thickness of the third layer of inner guide wall is 15 cm, leave 2 water discharge holes on the second layer of inner guide wall, the length and width of the water discharge hole are both 15 cm, set multiple layers of filter grating at the position of the water discharge hole, and the grating aperture is set to 0.5-8 cm.

[0084] After the inner guide wall is set, the slope of the bottom plane 10 in the wall body is set, the slope of each layer of bottom plane 10 is set to 1 / 4, and the depth of the sediment capture well is set to 30 cm. A filter material retaining wall is arranged behind the sediment capture well, the height of the filter material is 2 m, and the whole is divided into 4 layers, each layer is 50 cm high, and the filter material filling layers from bottom to top are gravel, gravel, ceramsite and pebble.

[0085] The outflow extension pipe 6 is made of PVC material, the water inlet of the PVC pipe is arranged in the innermost layer of the guide wall, and the water outlet is arranged in the river channel, and the top end of the PVC pipe is 10 cm away from the top end of the innermost layer of the guide wall.

[0086] In actual application, the tail water generated by irrigation is very small compared with the runoff generated by rainwater. When there is only tail water generated by irrigation, the residence time can reach 30 min, and when there is intermittent rainfall in Yunnan area, the residence time can reach 20 min, which can fully guarantee the settlement and conversion of colloidal particles and nitrogen and phosphorus substances.

[0087] Example 4

[0088] This embodiment adopts a PVC structure implementation:

[0089] The embodiment includes an outer body contour, an inner layer flow guide wall, a drain hole, an inclined capture well, a filter material partition wall, and an outflow extension pipe. First, a foundation pit with a length, width and height of 3m*3m*3m is excavated at the end of the ditch, and then a prefabricated micro sedimentation tank is directly placed in the foundation pit. The outer body contour of the micro sedimentation tank is 3m*3m*3m, the thickness is 1.5cm, three drain holes are left on the first layer of flow guide wall, the length and width of the drain holes are both 30cm, and the overflow port length* width = 50cm*10cm. Three layers of inner layer flow guide wall are set to form four wall body middle bottom planes 10, the width of each wall body middle bottom plane 10 is 73cm, the size of the drain holes on each layer of flow guide wall is length* width = 20*20cm, and a layer of filter grid is arranged at each drain hole, the filter grid aperture is 0.5-1cm. The slope of each layer of wall body middle bottom plane 10 is set to 1 / 4, and the depth of the capture well 9 is set to 20cm. The filter material retaining wall is arranged behind the capture well 9, the filter material height is 1.5, and the whole is divided into four layers, each layer height is 37cm. The filter material filling layers from bottom to top are gravel, gravel, ceramsite and pebble. The outflow extension pipe 6 is made of PVC material, the water inlet of the outflow extension pipe 6 is arranged in the innermost layer of flow guide wall, and the water outlet is arranged in the river channel. The top end of the PVC pipe is 10cm away from the top end of the innermost layer of flow guide wall.

[0090] In actual application process, the farmland tail water generated by irrigation is very small compared with the runoff generated by rainwater. When there is only tail water generated by irrigation, the residence time can reach 25min, and when there is intermittent rainfall in Yunnan area, the residence time can reach 15min, which can fully guarantee the settlement and conversion of colloidal particles and nitrogen and phosphorus substances.

[0091] Embodiment 5

[0092] The micro sedimentation tank method for the end of the farmland ditch is used. The water inlet of the micro sedimentation tank is arranged according to the size of the existing ditch. The farmland runoff collected by the ditch enters the first flow guide corridor through the water inlet of the micro sedimentation tank. The farmland runoff in the first flow guide corridor is divided into two sides of the micro sedimentation tank under the action of gravity. Part of the particles and colloidal substances in the farmland runoff will settle to the bottom of the two sides of the first flow guide corridor first, and then under the action of hydraulic scouring, they will finally be scoured into the capture well. The particles with light density will be intercepted by the filter material partition wall, and then will settle into the capture well under the action of gravity. The farmland runoff passing through the filter material partition wall enters the second flow guide corridor through the drain hole. The purification sequence of the farmland runoff is the same as that of the first sequence. Finally, the farmland runoff flows into the innermost layer of the flow guide wall, and then is discharged into the nearby river channel when the water level of the farmland runoff slowly rises to the position of the outflow extension pipe.

[0093] In summary, the present application provides a micro-pit system and method for the end of a farmland ditch, which can strengthen the collection and treatment capacity of rural domestic sewage, improve the interception and treatment capacity of farmland non-point source pollution, reduce the treatment load of subsequent measures, and has multiple functions and simple structure changes according to actual conditions.

[0094] The above embodiments have been described in detail, but the content is only the preferred embodiment of the present application, and cannot be considered to limit the scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the scope of the present application.

Claims

1. A micro sedimentation tank system for the end of farmland ditches, characterized in that: The micro sedimentation tank system for the end of farmland ditches includes an outer contour and 3-5 layers of inner guide walls. The outer contour is provided with water inlet holes, and the innermost inner guide wall is provided with an outlet extension pipe. The outlet extension pipe extends from the inside of the innermost inner guide wall to the outside of the outer contour. Each inner layer of the guide wall has drainage holes, and the drainage holes in each inner layer of the guide wall gradually decrease in size from the outside to the inside. The area between the outer contour and the outermost inner guide wall, as well as between the inner guide walls, forms the bottom plane in the middle of the wall. The bottom plane in the middle of the wall includes a slope with a gradient of 1:(4~7). The tail end of the slope is a capture well with a depth of 0.2~0.5m. The capture well is located between the outer contour and the outermost inner guide wall and between the inner guide walls of two adjacent layers, and the width of the capture well is equal to the width of the bottom plane. The slope and the capture well are referred to as an inclined capture well. A filter media partition wall is provided downstream of the capture well. The outer body outline is a cuboid, cube, cylinder, or a column with an elliptical cross-section, and the outer body outline has the same shape as the inner guide wall.

2. The micro sedimentation tank system for the end of farmland ditches according to claim 1, characterized in that: When the outer body contour is a cuboid or cube, the capture well is square in shape and located at the corner of the outer body contour or the inner guide wall, with a filter media partition wall installed at the location of the maximum hydraulic impact load. When the outer body profile is cylindrical or cylindrical with an elliptical cross-section, the capture well is located at 2 / 3 of the bottom plane of each layer along the water flow direction.

3. The micro sedimentation tank system for the end of farmland ditches according to claim 1, characterized in that: The outer contour and inner guide wall are made of reinforced concrete or corrosion-resistant PVC. When the outer contour is made of reinforced concrete, the thickness of the outer contour is 5-20cm. When the outer contour is made of corrosion-resistant PVC, the thickness of the outer contour is 0.5cm-1.5cm.

4. The micro sedimentation tank system for the end of farmland ditches according to claim 3, characterized in that: When the outer contour is made of reinforced concrete, the drainage holes are made of multiple layers of staggered grid mesh; when the outer contour is made of corrosion-resistant PVC, the drainage holes are made of a single layer of grid mesh.

5. The micro sedimentation tank system for the end of farmland ditches according to claim 1, characterized in that: The number of drainage holes is 1 to 3, and the drainage holes of the inner guide wall of the same layer are distributed on the same wall. The drainage holes of the inner guide walls of adjacent layers are staggered. The drainage holes of the nth inner guide wall are set according to the (n-1)th inner guide wall. That is, the drainage holes of the nth inner guide wall are distributed at the position after the water flows through the (n-1)th inner guide wall for half a circle. The same mesh size is installed on the drainage holes of the inner layer of the same flow guide wall, but the mesh size of the mesh installed on the drainage holes of the nth layer of the flow guide wall is smaller than the mesh size of the mesh installed on the drainage holes of the (n-1)th layer of the flow guide wall.

6. The micro sedimentation tank system for the end of farmland ditches according to claim 1, characterized in that: The inner guide wall decreases in elevation from the outside to the inside, and the height difference between two adjacent inner guide walls is 20~60cm. The height of the filter media partition wall is 1 / 4 to 1 / 2 of the height of the outer contour or the inner guide wall located on the outer layer among two adjacent inner guide walls; The drainage hole is 10cm to 15cm below the upper edge of the inner guide wall where it is located.

7. The micro sedimentation tank system for the end of farmland ditches according to claim 1, characterized in that: The outer contour is provided with an overflow port, which is at least 10cm lower than the upper edge of the outer contour and higher than the water inlet.

8. The micro sedimentation tank system for the end of farmland ditches according to claim 1, characterized in that: The top of the outflow extension pipe is 10-20cm lower than the drain hole of the innermost inner guide wall.

9. A construction method for a micro sedimentation tank system at the end of farmland ditches, characterized in that: The construction method for the micro sedimentation tank system at the end of farmland ditches is used to construct the micro sedimentation tank system for the end of farmland ditches as described in any one of claims 1-8. The construction method for the micro sedimentation tank system at the end of farmland ditches includes the following steps: Step 1: Excavate a foundation pit at the end of the ditch, construct the outer outline in the foundation pit and construct the inner guide wall from the outside to the inside, or place the prefabricated outer outline and inner guide wall in the foundation pit, with water inlet holes on the outer outline and overflow outlets set at the opposite positions of the water inlet holes. Step 2: Set the slope of the bottom plane in the middle of the inner guide wall, as well as the capture well and filter media partition wall; Step 3: Place one end of the outflow extension pipe inside the innermost inner guide wall, and extend the other end to the outside of the outer body contour.

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