Method for constructing ridge type wetland applied to non-point source pollution treatment

Abstract

The invention relates to a ridge-type wetland construction method applied to non-point source pollution treatment, which comprises the following steps: transforming an original farmland adjacent to a river by transforming an original field ridge, constructing a water inlet ridge ridge, constructing a water outlet ridge ridge, constructing a middle ridge ridge and constructing an ecological furrow, so as to form a ridge-type wetland formed by alternately combining ecological ridge ridges and ecological furrows; and the ridge type wetland can be used for agricultural production and can also realize non-point source pollution treatment. The method has the beneficial effects that the ridge-type wetland is formed by directly performing ecological transformation on the original farmland adjacent to the river, so that the ridge-type wetland has double attributes of agriculture and environmental protection, the construction is simple, and the transformation cost is low.

Description

Technical Field

[0001] This invention relates to the field of agricultural ecological environment governance technology, specifically to a method for constructing ridge-type wetlands for non-point source pollution control. Background Technology

[0002] Rural non-point source pollution refers to dissolved or solid pollutants from rural life and agricultural production activities, such as soil particles, nitrogen, phosphorus, pesticides, heavy metals, and organic or inorganic substances like livestock manure and domestic waste, which enter receiving water bodies (rivers, lakes, reservoirs, bays) from non-specific areas through surface runoff, farmland drainage, and groundwater seepage, causing eutrophication or other forms of pollution in the receiving water bodies.

[0003] Currently, effective control of agricultural non-point source pollution still faces numerous technical challenges. For example, the design of ecological ditch dimensions, substrate selection, and pollution reduction effects remain unclear. Effective treatment measures for the concentrated, short-term discharge of aquaculture wastewater and farmland runoff are also lacking. Existing methods for controlling agricultural non-point source pollution include adding vegetation buffer zones, ecological interception ditches, and constructed wetlands at the farmland's outlet. However, these methods require large land areas, are complex to construct, and are costly. Furthermore, the conflict between wetland use and land protection policy red lines, constrained by farmland protection policies, is also a significant factor limiting the application of non-point source pollution control technologies. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for constructing ridge wetlands for non-point source pollution control. This method involves directly transforming existing farmland adjacent to a river into ridge wetlands, giving the ridge wetlands both agricultural and environmental protection attributes. The method is simple to construct and has low transformation costs.

[0005] The objective of this invention is achieved through the following technical solution: A method for constructing ridge-type wetlands for non-point source pollution control includes: Transformation of existing field ridges: The existing field ridges of farmland are leveled and shaped to form a shaped soil layer. A foundation pit is excavated on the top side of the shaped soil layer. A foundation cushion layer is constructed by pouring concrete in the foundation pit. A ditch is excavated in the middle of the top surface of the shaped soil layer and the bottom of the ditch is leveled. A sludge drainage ditch is constructed by placing U-shaped troughs in the ditch and covering the opening of the U-shaped troughs with perforated covers. A ridge enclosure is constructed on the foundation cushion layer by laying perforated bricks. Constructing irrigation ridges: Inside the ridge enclosure at the irrigation end of the farmland, first lay permeable geotextile on the top surface of the shaped subsoil layer, then construct the first functional filler layer on the shaped subsoil layer by filling with ecological filler, then lay permeable geotextile on the top surface of the first functional filler layer and roll the permeable geotextile up to the top of the ridge enclosure, and finally construct the cultivation layer on the first functional filler layer by backfilling with planting soil and planting crops on the cultivation layer. Constructing irrigation ridges: Inside the ridge enclosure at the irrigation end of the farmland, first lay permeable geotextile on the top surface of the shaped soil layer, then construct a second functional filler layer on the shaped soil layer by filling with ecological filler, then lay permeable geotextile on the top surface of the second functional filler layer and roll the permeable geotextile up to the top of the ridge enclosure, and finally construct a cultivation layer on the second functional filler layer by backfilling with planting soil and planting crops on the cultivation layer. Constructing intermediate ridges: Within the enclosure of each ridge between the inlet and outlet ridges, first lay permeable geotextile on the top surface of the shaped subsoil layer, then construct a third functional filler layer on the shaped subsoil layer by filling with ecological filler, then lay permeable geotextile on the top surface of the third functional filler layer and roll the permeable geotextile up to the top of the ridge enclosure, and finally construct a cultivation layer on the third functional filler layer by backfilling with planting soil and planting crops on the cultivation layer. Constructing ecological furrows: After leveling the existing furrows between adjacent ridges, dig trenches with a certain slope, and then plant potted emergent aquatic plants in the trenches.

[0006] Furthermore, the thickness of the base layer is 150mm, the thickness of the first functional filler layer, the second functional filler layer, and the third functional filler layer are all 500mm, and the thickness of the tillage layer is 400mm.

[0007] Furthermore, the first functional filler layer includes a coarse-grained crushed stone layer, which is obtained by filling and compacting crushed stone with a particle size of 50mm-80mm.

[0008] Furthermore, the second functional filler layer includes a fine-grained volcanic rock layer, a fine sand layer, and a medium-grained volcanic rock layer constructed sequentially from bottom to top. The fine-grained volcanic rock layer is obtained by filling and compacting volcanic rocks with a particle size of 10mm-30mm. The fine sand layer is obtained by filling and compacting fine sand. The medium-grained volcanic rock layer is obtained by filling and compacting volcanic rocks with a particle size of 30mm-50mm.

[0009] Furthermore, the third functional filler layer includes multiple types of fine-grained crushed stone layer, rice gravel layer, biochar layer, shale particle layer, and coarse-grained volcanic rock layer.

[0010] Furthermore, the third functional filler layer comprises, from bottom to top, a fine-grained crushed stone layer, a gravel layer, a biochar layer, and a shale particle layer. The fine-grained crushed stone layer is obtained by filling and compacting crushed stone with a particle size of 20mm-40mm. The gravel layer is obtained by filling and compacting gravel with a particle size of 5mm-10mm. The biochar layer is obtained by filling and compacting thick lanthanum-modified biochar. The shale particle layer is obtained by filling and compacting weakly weathered shale particles.

[0011] Furthermore, the third functional filler layer comprises, from bottom to top, a gravel layer, a coarse-grained volcanic rock layer, and a fine-grained crushed stone layer. The gravel layer is obtained by filling and compacting gravel with a particle size of 5mm-10mm. The coarse-grained volcanic rock layer is obtained by filling and compacting volcanic rock with a particle size of 50mm-80mm. The fine-grained crushed stone layer is obtained by filling and compacting crushed stone with a particle size of 20mm-40mm.

[0012] Furthermore, the slope of the ecological furrow is 0.05-0.5.

[0013] Furthermore, emergent plants include canna lilies and pickerelweed, which are planted in a 1:1 ratio at a density of 15 plants / m². 2 .

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention transforms existing farmland adjacent to a river by modifying existing field ridges, constructing inlet ridges, outlet ridges, intermediate ridges, and ecological furrows. It creates ridge-type wetlands composed of alternating combinations of ecological ridges and ecological furrows. These ridge-type wetlands can increase the soil moisture content of the cultivated area and intercept nutrients from surface runoff for reuse in the fields, realizing the resource utilization of surface runoff and effectively increasing crop yields. Thus, the ridge-type wetlands possess both agricultural and environmental protection attributes and are conducive to the comprehensive utilization of farmland runoff.

[0015] 2. When constructing ridge-type wetlands, this invention only utilizes the area below the arable layer of the land, without affecting agricultural production. Crops can still be cultivated normally in the construction area, thereby achieving the adaptation of wetland land use to land protection.

[0016] 3. The construction of ridge-type wetlands in this invention is not limited by pipeline installation conditions, and can make use of existing ditches and adjacent farmland. It has the advantages of simple construction, low transformation cost, and convenient maintenance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall construction cross-section of the ridge-type wetland system in this invention; Figure 2 This is a schematic cross-sectional view of the construction of the water intake embankment in this invention; Figure 3 This is a schematic cross-sectional view of the construction of the water outlet embankment in this invention; Figure 4 This is a schematic cross-sectional view of the construction of the first type of intermediate ridge in this invention; Figure 5 This is a schematic cross-sectional view of the construction of the second type of intermediate ridge in this invention.

[0018] In the diagram: 1. Inlet ridge; 2. Middle ridge; 3. Outlet ridge; 4. Ecological furrow; 5. Shaped subsoil layer; 6. Foundation layer; 7. Ridge enclosure; 8. Cultivated layer; 9. Crops; 10. Emergent aquatic plants; 11. Coarse gravel layer; 12. Fine volcanic rock layer; 13. Fine sand layer; 14. Medium volcanic rock layer; 15. Gravel layer; 16. Biochar layer; 17. Shale particle layer; 18. Coarse volcanic rock layer; 19. Fine gravel layer; 20. Drainage ditch. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0020] Example 1 To enhance the non-point source pollution self-management capacity of existing farmland without impacting agricultural production, this invention utilizes existing ditches and adjacent river farmland on-site. Through direct ecological transformation of the existing adjacent river farmland, a ridge-type wetland is constructed, consisting of alternating ecological ridges and ecological furrows (4). This ridge-type wetland possesses both agricultural and environmental attributes. The ecological ridges are transformed from existing field ridges, specifically composed of ridge enclosures (7), ecological filler, and planting soil. The planting soil is used for planting crops, while the ecological filler purifies surface runoff while ensuring suitable growing conditions for crops, guaranteeing their effective growth. The ecological furrows (4) are transformed from existing furrows between field ridges, further purifying surface runoff.

[0021] like Figure 1 As shown, the ecological ridges in this invention are divided into inlet ridges 1, intermediate ridges 2, and outlet ridges 3, and are sequentially combined according to the water flow direction and waterway channels. Inlet ridge 1 is constructed from the ridges at the water inlet end of the farmland, outlet ridge 3 is constructed from the ridges at the water outlet end of the farmland, and intermediate ridge 2 is constructed from all the ridges between inlet ridge 1 and outlet ridge 3. The construction process for inlet ridge 1, intermediate ridge 2, and outlet ridge 3 is the same, the difference being in the ecological filler material. Different intermediate ridges 2 can also use different ecological fillers in different combinations according to actual needs. Surface runoff flows sequentially from the water inlet end of the farmland through the inlet ridges, intermediate ridges, and outlet ridges before being discharged from the water outlet end. During the flow, the runoff is purified by the ecological filler material and ecological furrows, reducing drainage pollution.

[0022] The construction of the above-mentioned ridge-shaped wetland includes the following specific construction contents: (1) Transformation of existing field ridges: The existing field ridges of the farmland are leveled and shaped to form a shaped soil layer 5. A foundation pit is excavated on the top side of the shaped soil layer 5. A foundation cushion layer 6 is constructed by pouring concrete in the foundation pit. A ditch is excavated in the middle of the top surface of the shaped soil layer 5 and the bottom of the ditch is leveled. A ditch 20 is constructed by placing a U-shaped trough in the ditch and covering the opening of the U-shaped trough with a perforated cover plate. A ridge enclosure 7 is constructed on the foundation cushion layer 6 by laying perforated bricks.

[0023] (2) Constructing the irrigation ridge 1: Inside the ridge enclosure 7 at the irrigation end of the farmland, first lay permeable geotextile on the top surface of the shaped soil layer 5, then construct the first functional filler layer on the shaped soil layer 5 by filling with ecological filler, then lay permeable geotextile on the top surface of the first functional filler layer and roll the permeable geotextile up to the top of the ridge enclosure 7, and finally construct the cultivation layer 8 by backfilling planting soil on the first functional filler layer and plant crops 9 on the cultivation layer 8.

[0024] (3) Constructing the water outlet ridge 3: Inside the ridge enclosure 7 at the water outlet end of the farmland, first lay permeable geotextile on the top surface of the shaped soil layer 5, then construct the second functional filler layer on the shaped soil layer 5 by filling with ecological filler, then lay permeable geotextile on the top surface of the second functional filler layer and roll the permeable geotextile up to the top of the ridge enclosure 7, and finally construct the cultivation layer 8 by backfilling planting soil on the second functional filler layer and plant crops 9 on the cultivation layer 8.

[0025] (4) Constructing intermediate ridges 2: In the ridge enclosures 7 between the water inlet ridge 1 and the water outlet ridge 3, first lay permeable geotextile on the top surface of the shaped soil layer 5, then construct a third functional filler layer on the shaped soil layer 5 by filling with ecological filler, then lay permeable geotextile on the top surface of the third functional filler layer and roll the permeable geotextile up to the top of the ridge enclosure 7, and finally construct a cultivation layer 8 on the third functional filler layer by backfilling with planting soil and planting crops 9 on the cultivation layer 8.

[0026] (5) Constructing ecological furrows 4: After leveling the existing furrows between adjacent ridges, dig trenches with a certain slope, and then plant potted emergent aquatic plants 10 in the trenches.

[0027] As surface runoff flows through farmland, it enters the ecological ridge through the porous bricks in the ridge enclosure 7. After being purified by the filler material within the ecological ridge, it flows into the ecological furrow through the porous bricks for further purification. The sludge formed by runoff deposition enters the sludge drainage ditch through a porous cover and is then discharged. In this embodiment, when constructing the sludge drainage ditch, a ditch 0.3m deep and 0.3m wide is excavated after leveling the existing furrow. After manually leveling the bottom of the ditch, a U-shaped channel with dimensions of 300mm*300mm*1000mm, made of polymer material, is placed inside the ditch, and then a porous cover is placed over the opening of the U-shaped channel.

[0028] In this embodiment, the ecological furrow 4 is 0.5m-1.5m wide and 0.5m-0.8m deep, with a slope of 0.05-0.5, and an optimal slope of 0.15-0.25. Emergent plants include canna lilies and pickerelweed, planted in a 1:1 ratio at a density of 15 plants / m². 2 Emergent plants, which are both aquatic and terrestrial, have well-developed root systems that can absorb dissolved nutrients such as nitrogen and phosphorus from the water and promote the decomposition of organic matter through photosynthesis. Simultaneously, their root systems provide habitats for microorganisms, forming biofilms that synergistically degrade pollutants. Furthermore, emergent plants can slow water flow, increase hydraulic retention time, and enhance purification efficiency.

[0029] In this embodiment, the thickness of the base layer 6 is 150mm, the thickness of the first functional filler layer, the second functional filler layer, and the third functional filler layer is 500mm, and the thickness of the tillage layer 8 is 400mm.

[0030] like Figure 2 As shown, the first functional filler layer includes a coarse gravel layer 11, which is obtained by filling and compacting gravel with a particle size of 50mm-80mm. The gravel layer mainly serves as a support and preliminary filter, intercepting large suspended particles (such as silt), reducing water flow impact, and providing a stable foundation for the subsequent purification layer. At the same time, the large pore structure of the gravel facilitates water flow and avoids clogging.

[0031] like Figure 3As shown, the second functional packing layer comprises, from bottom to top, a fine-grained volcanic rock layer 12, a fine sand layer 13, and a medium-grained volcanic rock layer 14. The fine-grained volcanic rock layer 12 is formed by compacting volcanic rocks with a particle size of 10mm-30mm, and has a thickness of 200mm. The fine sand layer 13 is formed by compacting fine sand, and has a thickness of 100mm. The medium-grained volcanic rock layer 14 is formed by compacting volcanic rocks with a particle size of 30mm-50mm, and has a thickness of 200mm. The fine-grained volcanic rock layer 12 utilizes the porous structure of volcanic rock to achieve a large specific surface area, enabling the adsorption of pollutants such as ammonia nitrogen and heavy metals, while simultaneously promoting nitrification and denitrification to reduce nitrogen content. The fine sand layer 13 removes fine suspended solids and colloidal substances, improves water transparency, prevents clogging of subsequent layers, and provides a surface for microbial attachment. The medium-grained volcanic rock layer 14 is used to further adsorb residual pollutants and regulate water flow velocity to ensure sufficient hydraulic retention time and enhance purification efficiency.

[0032] like Figure 4 , Figure 5 As shown, the third functional filler layer includes a fine-grained crushed stone layer 19, a gravel layer 15, a biochar layer 16, a shale particle layer 17, and a coarse-grained volcanic rock layer 18. Different third functional filler layers for different intermediate ridges 2 can be selected and combined in a differentiated manner according to actual needs. Specifically, the fine-grained crushed stone layer 19 is obtained by filling and compacting crushed stone with a particle size of 20mm-40mm; the gravel layer 15 is obtained by filling and compacting gravel with a particle size of 5mm-10mm; the biochar layer 16 is obtained by filling and compacting thick lanthanum-modified biochar; the shale particle layer 17 is obtained by filling and compacting weakly weathered shale particles; and the coarse-grained volcanic rock layer 18 is obtained by filling and compacting volcanic rock with a particle size of 50mm-80mm. The shale layer serves as a transitional layer, connecting the upper and lower layers. It filters medium-sized particulate matter and provides a carrier for the growth of microbial biofilms, enhancing biodegradation capacity. The biochar layer 16 utilizes the high adsorption capacity of biochar to adsorb organic pollutants, phosphorus, and heavy metals. Furthermore, the modified surface of biochar can catalyze degradation reactions, improving COD removal rate. The shale particles in the shale particle layer 17 are rich in minerals and can adsorb nutrients such as phosphates through ion exchange, reducing the risk of eutrophication and regulating pH. The coarse-grained volcanic rock layer 18 has larger pores, making it suitable for high flow rates. It mainly plays an adsorption and buffering role, preventing system overload.

[0033] The ridge-type wetland constructed through the above-described construction process allows for alternating buffering of high concentrations of nitrogen and phosphorus nutrients in farmland surface runoff between the ecological furrows (4) and the ecological filler material. Specifically, when nutrient concentrations are high, the ecological filler material adsorbs and reduces nutrient concentrations in the water; when nutrient concentrations are low, the ecological filler material decomposes the nutrients, ensuring sufficient nutrients for plant growth. Ultimately, the ridge-type wetland effectively degrades nitrogen, phosphorus, and COD levels in the incoming water while simultaneously ensuring the effective growth of crops (9).

[0034] Example 2 Based on the above embodiment one, the third functional filler layer in this embodiment is as follows: Figure 4 As shown, the structure comprises, from bottom to top, a fine-grained gravel layer 19, a gravel layer 15, a biochar layer 16, and a shale particle layer 17. The fine-grained gravel layer 19 is formed by compacting gravel with a particle size of 20mm-40mm, and has a thickness of 150mm; the gravel layer 15 is formed by compacting gravel with a particle size of 5mm-10mm, and has a thickness of 100mm; the biochar layer 16 is formed by compacting thick lanthanum-modified biochar, and has a thickness of 150mm; and the shale particle layer 17 is formed by compacting weakly weathered shale particles, and has a thickness of 100mm.

[0035] Example 3 Based on the above embodiment one, the third functional filler layer in this embodiment is as follows: Figure 5 As shown, the structure comprises, from bottom to top, a layer of gravel 15, a layer of coarse-grained volcanic rock 18, and a layer of fine-grained crushed stone 19. The gravel layer 15 is formed by compacting gravel with a particle size of 5mm-10mm, and has a thickness of 200mm. The coarse-grained volcanic rock layer 18 is formed by compacting volcanic rock with a particle size of 50mm-80mm, and has a thickness of 100mm. The fine-grained crushed stone layer 19 is formed by compacting crushed stone with a particle size of 20mm-40mm, and has a thickness of 200mm.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for constructing a ridge-type wetland for non-point source pollution control, characterized in that, The application relates to a farmland ecological reconstruction method. The method comprises the following steps: constructing an inlet ridge (1) in the ridge enclosure (7) at the water inlet end of the farmland, laying water-permeable geotextile on the top surface of the shaped soil layer (5) first, then constructing a first functional filler layer on the shaped soil layer (5) by filling ecological fillers, laying water-permeable geotextile on the top surface of the first functional filler layer and rolling the water-permeable geotextile to the top of the ridge enclosure (7) on the side, finally constructing a ploughing layer (8) on the first functional filler layer by backfilling planting soil and planting crops (9) on the ploughing layer (8); constructing an outlet ridge (3) in the ridge enclosure (7) at the water outlet end of the farmland, laying water-permeable geotextile on the top surface of the shaped soil layer (5) first, then constructing a second functional filler layer on the shaped soil layer (5) by filling ecological fillers, laying water-permeable geotextile on the top surface of the second functional filler layer and rolling the water-permeable geotextile to the top of the ridge enclosure (7) on the side, finally constructing a ploughing layer (8) on the second functional filler layer by backfilling planting soil and planting crops (9) on the ploughing layer (8); constructing an intermediate ridge (2) in each ridge enclosure (7) between the inlet ridge (1) and the outlet ridge (3), laying water-permeable geotextile on the top surface of the shaped soil layer (5) first, then constructing a third functional filler layer on the shaped soil layer (5) by filling ecological fillers, laying water-permeable geotextile on the top surface of the third functional filler layer and rolling the water-permeable geotextile to the top of the ridge enclosure (7) on the side, finally constructing a ploughing layer (8) on the third functional filler layer by backfilling planting soil and planting crops (9) on the ploughing layer (8); constructing an ecological ridge ditch (4) by excavating a certain slope ditch after leveling the original ridge ditch between the adjacent ridges, and then planting water and land double-born emergent plants (10) in the ditch.

2. The method according to claim 1, wherein the method is used for the construction of a ridge-type wetland for the treatment of non-point source pollution. The thickness of the foundation cushion layer (6) is 150 mm, the thickness of the first functional filler layer, the second functional filler layer and the third functional filler layer is 500 mm, and the thickness of the ploughing layer (8) is 400 mm.

3. The method according to claim 1, wherein the method is characterized in that: The first functional filler layer comprises a coarse-grained gravel layer (11) obtained by filling and compacting gravel with a particle size of 50-80 mm.

4. The method according to claim 1, wherein the method is characterized in that: The second functional filler layer comprises a fine-grained volcanic stone layer (12), a fine sand layer (13) and a medium-grained volcanic stone layer (14) which are sequentially constructed from bottom to top, the fine-grained volcanic stone layer (12) is obtained by filling and compacting volcanic stones with a particle size of 10-30 mm, the fine sand layer (13) is obtained by filling and compacting fine sand, and the medium-grained volcanic stone layer (14) is obtained by filling and compacting volcanic stones with a particle size of 30-50 mm.

5. The method according to claim 1, wherein the method is characterized in that: The third functional filler layer comprises multiple kinds of fine-grained gravel layer (19), rice stone layer (15), biochar layer (16), shale particle layer (17) and coarse-grained volcanic rock layer (18).

6. The method according to claim 5, wherein the method is characterized in that: The third functional filler layer comprises fine-grained gravel layer (19), rice stone layer (15), biochar layer (16) and shale particle layer (17) built in sequence from bottom to top, the fine-grained gravel layer (19) is obtained by packing and compacting gravel with a particle size of 20mm-40mm, the rice stone layer (15) is obtained by packing and compacting rice stone with a particle size of 5mm-10mm, the biochar layer (16) is obtained by packing and compacting thick lanthanum modified biochar, and the shale particle layer (17) is obtained by packing and compacting weakly weathered shale particles.

7. The method according to claim 5, wherein the method is characterized in that: The third functional filler layer comprises rice stone layer (15), coarse-grained volcanic rock layer (18) and fine-grained gravel layer (19) built in sequence from bottom to top, the rice stone layer (15) is obtained by packing and compacting rice stone with a particle size of 5mm-10mm, the coarse-grained volcanic rock layer (18) is obtained by packing and compacting volcanic rock with a particle size of 50mm-80mm, and the fine-grained gravel layer (19) is obtained by packing and compacting gravel with a particle size of 20mm-40mm.

8. The method according to claim 1, wherein the method is characterized in that: The trench slope of the ecological ridge and trench (4) is 0.05-0.

5.

9. The method according to claim 1, wherein the method is characterized in that: The emergent plants include canna and sword grass, and the canna and the sword grass are planted in a quantity of 1:1, and the planting density is 15 plants / m 2 .

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