CN206289052U - Process the improved surface artificial wetland of agricultural surface runoff pollutant - Google Patents

Abstract

The utility model is related to a kind of surface current artificial wetland, specifically discloses a kind of improved surface artificial wetland for processing agricultural surface runoff pollutant.It is heavy eventually to be provided with permeable wall between gathering ground and plant absorption area including plant absorption area and whole heavy gathering ground；The end, heavy gathering ground was provided with inlet channel, and overflow canal to be opened/closed is communicated with inlet channel.The utility model has the advantages that：1）Reduce the floor space of the improved surface artificial wetland for the treatment of agricultural surface runoff pollutant, substantially reduce dependence of the artificial swamp to landform；2）Solve the problems, such as that the pollutants removal rate caused due to the space-time inhomogeneities of rainfall is unstable；3）The alluvial of the suspended contaminants such as silt is concentrated in heavy gathering ground eventually, and without frequently carrying out desilting to whole artificial swamp, maintenance cost is substantially reduced.

Description

Improved Surface Flow Constructed Wetlands for Treating Farmland Surface Runoff Pollutants

technical field

The invention relates to a constructed wetland, in particular to a surface flow constructed wetland.

Background technique

At present, in addition to source control technologies such as planting system optimization, scientific fertilization, pesticide reduction, and residue control, technologies for non-point source pollution in farmland also include ecological field ridges, ecological interception belts, ecological interception ditches, front Storage technology, artificial wetland technology.

The ecological field ridge is to increase the height of the existing field ridge by 10-15cm, which can effectively prevent surface runoff during 30-50mm rainfall, or reduce irrigation water in the early stage of fertilization to reduce the depth of surface water, thereby reducing most of the farmland surface runoff. Plants can be planted on both sides of the field ridge to form an isolation zone, which can effectively block the loss of nitrogen and phosphorus nutrients and control the migration of residual pesticides to the water body when surface runoff occurs. , the effectiveness of the measure is low.

The ecological interception zone is to build an ecological isolation zone around the dry land. The sediment, nitrogen and phosphorus nutrients, pesticides, etc. In the ecological interception zone, the plants planted in the interception zone can absorb the nitrogen and phosphorus nutrients in the runoff, thereby reducing the migration of nitrogen and phosphorus carried by the surface runoff to the water body. The ecological interception zone needs to be set with different widths according to the land type, slope, and soil type. The width ranges from 10 to 150m, and it occupies a large area, which is especially unfavorable for places where land resources are scarce.

Ecological interception ditch refers to a farmland muddy ditch ecosystem with a certain width and depth, composed of water, soil and organisms, with its own unique structure and corresponding ecological functions, also known as farmland ditch wetland ecosystem. Ecological ditches can reduce soil erosion and nitrogen and phosphorus content in surface water through a series of functions such as sediment retention, soil adsorption, plant absorption, and biodegradation. Harvesting plants solves the problem of secondary pollution. Aquatic plants in ditches have a good ability to absorb nitrogen and phosphorus in sewage. Aquatic plants can be harvested by farmers, which solves the problem of secondary pollution. Flexible construction, no power consumption, and low operating costs. However, the plants in the ditch need to be harvested and replanted regularly. The ditch is generally large in size and occupies a large area. The interception of a large number of plants on sediment can easily cause ditch silting.

The pre-reservoir technology is to adjust the residence time of incoming water in the pre-reservoir area, so that the sediment in the runoff sewage and the pollutants adsorbed on the sediment settle in the pre-reservoir; use the ecosystem in the pre-reservoir to absorb Remove pollutants from water bodies and sediments. Front-end storage technology is one of the effective measures to prevent non-point source pollution because of its low cost and suitability for various conditions. However, the treatment system is huge and easily restricted by terrain.

Constructed wetland technology is a ground similar to a swamp that is artificially constructed and controlled to operate. Sewage and sludge are distributed to the artificially constructed wetland in a controlled manner. During the flow of sewage and sludge in a certain direction, the main It is a technology to treat sewage and sludge by using the physical, chemical and biological synergy of soil, artificial medium, plants and microorganisms. Constructed wetland is a comprehensive ecosystem. It applies the principles of species symbiosis, material recycling and regeneration, and the principle of structure and function coordination in the ecosystem. On the premise of promoting a virtuous cycle of pollutants in wastewater, it fully exerts the production potential of resources and prevents environmental degradation. Re-pollution, to obtain the best benefits of sewage treatment and resource utilization.

Constructed wetlands are divided into surface flow constructed wetlands, subsurface flow constructed wetlands, and vertical flow constructed wetlands. For agricultural non-point source pollution, especially the interception of nitrogen and phosphorus in farmland surface runoff, surface flow constructed wetlands have the advantages of less investment, simple operation, low operating cost, and good landscape effects. Although subsurface flow wetlands have the advantages of less land occupation and good sanitary conditions, compared with surface flow systems, subsurface flow wetland treatment systems have disadvantages such as high investment and low removal efficiency of nitrogen and phosphorus. Vertical flow wetlands have higher infrastructure costs and are more likely to breed mosquitoes and flies.

However, the use of surface flow constructed wetlands to treat farmland surface runoff pollutants still has the following defects:

1. Since the surface runoff of farmland contains a large amount of pollutants such as nitrogen and phosphorus (caused by fertilization of crops), a relatively large plant purification system is required to purify the pollutants, resulting in an excessively large area of artificial wetlands, and the construction of wetlands is affected by the terrain. limitations and high construction costs. The primary issue in the design of surface flow constructed wetlands is whether the construction of the wetland conforms to the terrain conditions and is economically feasible, the content involved includes the availability of the required land area, and whether the estimated cost is affordable. Due to the above defects, the use of surface flow constructed wetlands to deal with farmland surface runoff is greatly limited.

2. During the purification process, a large amount of sediment and other pollutants in the surface runoff of farmland enter the surface flow constructed wetland, causing the surface flow constructed wetland to accumulate silt rapidly. In order to ensure the treatment effect of the wetland, it is necessary to carry out regular desilting and plant replenishment on the entire wetland First, due to the large area of surface flow constructed wetlands, the cost of wetland maintenance is high.

3. Due to the temporal and spatial inhomogeneity of rainfall, a large amount of surface runoff in a short period of time will lead to overloading of constructed wetlands. At the same time, the large runoff causes the sewage flow rate to be too fast, and the residence time of the sewage in the constructed wetland is too short, resulting in the problem of unstable pollutant removal rate.

Contents of the invention

In order to solve the problems in the prior art that the improved surface flow constructed wetland for treating farmland surface runoff pollutants occupies a large area, is difficult to desilt and maintain, and has unstable pollutant removal effects, the present invention provides a method for treating farmland surface runoff pollutants Improved Surface Flow Constructed Wetlands.

The technical scheme adopted in the present invention is: the improved surface flow artificial wetland for treating farmland surface runoff pollutants, including the final sedimentation catchment area and the plant absorption area, planting plants that can absorb nitrogen and phosphorus in the plant absorption area; There is a permeable wall between the water collection area and the plant absorption area; the final sinking water collection area is provided with an inlet channel, and an openable overflow channel is connected to the water inlet channel. By opening the overflow channel, the water in the inlet channel can be The incoming water is directed into the receiving water body.

In order to solve the problem that the surface flow artificial wetland occupies a large area and the treatment effect is unstable, the inventor proposes: if the shortcomings of large instantaneous flow of surface runoff, short collection time, and intermittent treatment of incoming water can be transformed into small flow, incoming water The continuous and stable characteristics can ensure that the surface runoff has enough residence time in the wetland, so that the plants can fully absorb the nitrogen and phosphorus components in the surface runoff, and the organic matter is effectively degraded, so the area occupied by the treatment system can be greatly reduced. In order to meet the above requirements, the present invention divides the artificial wetland into the final sedimentation catchment area and the plant absorption area, and sets a permeable wall between the final sedimentation catchment area and the plant absorption area, through the slow water permeability of the permeable wall, to achieve regulation The spatio-temporal inhomogeneity of water volume converts the surface runoff collected in a short period of time into the water volume that can only be penetrated in a long time (for example, 50m ³ surface runoff collected in 20 minutes is converted into 0-50m ³ /d surface runoff), and the flow rate is greatly reduced. Ensure that the incoming water in the plant absorption area is stable, uniform and has sufficient residence time, the wetland area is greatly reduced, the facilities are not overloaded, and the treatment effect is stable and reliable.

It should be noted that if the sand content or suspended matter content of the incoming water is high, it will easily cause the pores of the permeable wall to be blocked, making this scheme impossible to implement. Therefore, in addition to the function of collecting surface runoff, the function of setting the final sedimentation catchment area in the present invention also has the function of sedimentation in suspended matter such as sediment in water. Due to the interception effect of the permeable wall on incoming water, the flow velocity of the surface runoff entering the final settling catchment area will be greatly reduced, making it easier for the residual suspended matter in the water to settle in the final settling catchment area. In addition, the present invention can also further remove suspended matter such as sediment by being equipped with a pretreatment system, so as to reduce the dredging frequency of the final sedimentation catchment area and the permeable wall. The pretreatment system can be a settling tank or an ecological intercepting ditch installed in front of the final sedimentation catchment area, which can intercept or settle suspended matter such as sediment in the water. The surface runoff enters the final sedimentation catchment after pretreatment, which can reduce the sediment load in the final sedimentation catchment and reduce the area occupied by the final sedimentation catchment.

Due to the sedimentation effect of the final sedimentation catchment area and the separation effect of the permeable wall, only a very small amount of suspended matter can enter the plant absorption area. Therefore, it is almost only necessary to clean the final sedimentation catchment area and the permeable wall during dredging, which greatly reduces the Maintenance costs of constructed wetlands.

Due to the interception effect of the permeable wall on the water flow, a prolonged rainstorm may cause the water level in the final sinking catchment to rise, causing the water to overflow the final sinking catchment or overflow the permeable wall. However, according to the characteristics of farmland surface runoff, the pollutant content in the runoff is concentrated in the first 0-1 hour of rainfall, and the pollutant content in the runoff in the late rainfall period is very low. Therefore, the constructed wetland can only deal with the surface runoff in the early stage of rainfall, and the surface runoff in the later stage of rainfall can be directly discharged into rivers or introduced into receiving water bodies such as rainwater drainage pipe networks. According to this, in order to prevent the overflow of the water body in the final subsidence catchment area caused by the setting of the permeable wall, the present invention is provided with an openable and closable overflow channel on the water inlet channel, and the incoming water in the water inlet channel can be directly discharged by opening the overflow channel. Introduce the receiving water body to ensure the efficient and stable operation of the entire constructed wetland.

As a further improvement of the present invention, the wall material of the permeable wall is selected from one or more of slag, zeolite, ceramics, activated carbon, limestone, and broken bricks. More preferably, the wall of the permeable wall is covered with a rigid mesh cage for shaping and strengthening the wall. The permeable wall can be formed integrally and have pores (such as permeable concrete) on the wall, or it can be built with dispersed granular materials (activated carbon, broken bricks, etc.). When the permeable wall is made of dispersed granular materials, the rigid cage can be used to cover the wall to shape the dispersed granular materials and strengthen the permeable wall. At the same time, the cage structure will not affect The water permeability of the permeable wall is affected, which can make the water flow through the permeable wall evenly, so as to adjust the spatiotemporal inhomogeneity of the incoming water and ensure the water permeability of the permeable wall. The material of the cage can be made of metal or other rigid materials. The wall material of the permeable wall can be selected from one or any combination of slag, zeolite, activated carbon and broken bricks. These materials have strong adsorption capacity for nitrogen and phosphorus, so that the permeable wall can also absorb nitrogen and phosphorus, reduce the load of the plant absorption area, and further reduce the area occupied by the constructed wetland. The material ratio and water permeability of the permeable wall can be determined according to calculation and field experiments. After calculation, material prefabrication and experimental correction are carried out to finally determine the material ratio.

The calculation formulas for permeable walls are as follows:

Porosity = (1-bulk density of granular material/apparent density of granular material) × 100%

Permeable flow = permeation velocity x permeable wall area x void ratio

As a further improvement of the present invention, the plant absorption area is provided with a baffle (. More preferably, the structure of the baffle is: use slag, zeolite, pottery, activated carbon, limestone, broken brick One or any several of them are used as materials, and the material is fixed on the outside of the brick wall or concrete wall through a rigid cage to form the baffle. Setting the baffle can avoid the dead angle of the water flow in the plant absorption area The baffles can be made of slag, zeolite, activated carbon, broken bricks and other materials with strong adsorption capacity for nitrogen and phosphorus, and a rigid cage is set to attach these materials to the outside of the masonry wall for reinforcement, which can further strengthen the absorption of nitrogen. , Phosphorus adsorption, thereby reducing the plant absorption area load, thereby further reducing the constructed wetland area.

As a further improvement of the present invention, the final sedimentation catchment area accounts for 10-40% of the total area of the constructed wetland, and the plant absorption area accounts for 60-90% of the total area of the artificial wetland. More preferably, the water level in the plant absorption area is below 2m, and the final sedimentation area The water level in the water area is higher than the plant absorption area. The area of the plant absorption zone is determined according to the water permeability of the permeable wall and the design residence time. The smaller the water permeability, the smaller the area of the plant absorption zone. The water level in the plant absorption area is generally below 2m. If the water level is too high, the types of plants to be planted will be limited.

As a further improvement of the present invention, floating plants are planted in the final sinking catchment area, so that the final sinking catchment area has a certain function of absorbing pollutants such as nitrogen and phosphorus.

As a further improvement of the present invention, floating, submerged or emergent plants are planted in the plant absorption area. The plants in the plant absorption area should be selected according to the local climate, plant pollutant absorption rate, local fertilization conditions and other factors, and the floating, submerged and emergent plants that have a strong absorption effect on nitrogen, phosphorus and other pollutants should be planted.

The invention also discloses an application of the improved surface flow artificial wetland for treating farmland surface runoff pollutants for treating domestic wastewater.

The invention can be used to treat domestic wastewater. When in use, the domestic wastewater is introduced into the final sedimentation catchment area for storage, and the domestic wastewater in the final sedimentation catchment area slowly enters the plant absorption area through the permeable wall, so that the incoming water is uniform and stable. into the wetland system for treatment. It is especially suitable for the treatment and regulation of domestic wastewater in rural areas and towns where drainage is frequent day and night. In this scheme, permeable concrete can be selected as the permeable wall.

The beneficial effects of the present invention are: 1) reduce the occupied area of the improved surface flow constructed wetland for processing farmland surface runoff pollutants, and greatly reduce the dependence of the constructed wetland on topography; 2) solve the problems caused by the temporal and spatial inhomogeneity of rainfall The problem of unstable pollutant removal rate; 3) The deposition of suspended pollutants such as sediment is concentrated in the final sedimentation catchment area, so there is no need to frequently desilt the entire constructed wetland, and the maintenance cost is greatly reduced; 4) The area of the constructed wetland is reduced Make plant replanting easier.

Description of drawings

Fig. 1 is a top view of the improved surface flow constructed wetland for treating farmland surface runoff pollutants according to the present invention.

Fig. 2 is a cross-sectional schematic diagram of the improved surface flow constructed wetland for treating farmland surface runoff pollutants according to the present invention.

Fig. 3 is a schematic diagram of the baffle plate of the improved surface flow constructed wetland for treating farmland surface runoff pollutants according to the present invention.

Fig. 3a is a front view of the improved surface flow constructed wetland baffle for treating farmland surface runoff pollutants of the present invention.

Fig. 3b is a top view of the improved surface flow constructed wetland baffle of the present invention for treating farmland surface runoff pollutants.

The marks in the picture are: 1-final sink catchment area, 2-plant absorption area, 3-permeable wall, 4-inlet channel, 5-overflow channel, 6-baffle plate, 7-outlet channel, 8-mesh cage Fixed absorbent material, 9-brick wall.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1 and Figure 2, the improved surface flow artificial wetland for treating farmland surface runoff pollutants of the present invention includes a final sedimentation catchment area 1 and a plant absorption area 2, and the final sedimentation catchment area 1 accounts for 20% of the total area of the wetland , the plant absorption area 2 accounts for 80% of the total wetland area; floating plants are planted in the final sink catchment area 1, and emergent plants are planted in the plant absorption area 2; Flow plate 6 is made up of adsorption material 8 and brick wall 9 fixed by mesh cage, adopts granular activated carbon as adsorption material in the rigid mesh cage, and granular activated carbon is fixed on the outside of brick wall 9 by metal mesh cage to form; A permeable wall 3 is set between the water collection area 1 and the plant absorption area 2; the main material of the permeable wall 3 is granular activated carbon, and the outside of the wall is covered with a metal mesh cage to reinforce the permeable wall 3; Zone 1 is provided with an inlet channel 4, and an openable and closable overflow channel 5 is connected to the inlet channel 4. By opening the overflow channel 5, the incoming water in the inlet channel 4 can be introduced into the receiving water body.

At the initial stage of rainfall, the farmland surface runoff enters the final sedimentation catchment area 1 of the constructed wetland through the inlet channel 4, and the collected water volume is 50m ³ . In the final sedimentation catchment area 1, due to the interception effect of the permeable wall 3, the water flow speed slows down, and the suspended matter such as residual sediment in the water is effectively settled, and the incoming water with a very low solid content is intercepted by the permeable wall 3. The incoming water slowly and evenly passes through the permeable wall 3 at a rate of 50m ³ /d, and at the same time, the nitrogen and phosphorus in the water are absorbed by the permeable wall 3 made of activated carbon, forming a slow, Uniform water flow ensures that the incoming water has sufficient residence time in the plant absorption area 2 so that the emergent plants planted in the plant absorption area 2 can fully absorb pollutants such as nitrogen and phosphorus. The baffle 6 can prevent the formation of dead angles or cross-flow, and the baffle 6 also has a certain absorption capacity for pollutants such as nitrogen and phosphorus. The incoming water treated by the constructed wetland enters the receiving water body through the outlet channel 7 or overflow. It can also enter the subsequent treatment facilities such as oxidation ponds to continue advanced treatment before entering the receiving water body. If it rains for a long time, because the concentration of rainwater pollutants in the later period is very low, the overflow channel 5 located on the intake channel 4 of the constructed wetland can be opened, so that the later rainwater can be directly discharged into the receiving water body.

Claims (8)

1. The improved surface flow artificial wetland for processing farmland surface runoff pollutants comprises a plant absorption area (2), and the plant absorption area (2) is planted with plants that absorb nitrogen and phosphorus; it is characterized in that: it also includes a final Settling catchment area (1), a permeable wall (3) is set between the final sinking catchment area (1) and the plant absorption area (2); the final sinking catchment area (1) is provided with an inlet channel (4) , an openable and closable overflow channel (5) is communicated with the water inlet channel (4), and the incoming water in the water inlet channel (4) can be introduced into the receiving water body by opening the overflow channel (5). 2. The improved surface flow constructed wetland for treating farmland surface runoff pollutants according to claim 1, characterized in that: the wall of the permeable wall (3) is covered with a rigid cage for modeling and strengthening the wall. 3. The improved surface flow artificial wetland for treating farmland surface runoff pollutants according to claim 1, characterized in that: the plant absorption area (2) is provided with a baffle plate (6) having a flow guiding function. 4. The improved surface flow constructed wetland for treating farmland surface runoff pollutants according to claim 3, characterized in that: the structure of the baffle (6) is: the adsorption material (8) fixed by the mesh cage is fixed The baffle (6) is formed on the outside of the brick wall or concrete wall (9). 5. The improved surface flow constructed wetland for treating farmland surface runoff pollutants according to claim 1, characterized in that: the final sink catchment area (1) accounts for 10 to 40% of the total area of the constructed wetland, and the plant absorption area (2) It accounts for 60-90% of the total constructed wetland area. 6. The improved surface flow artificial wetland for treating farmland surface runoff pollutants according to claim 1, characterized in that: the water level in the plant absorption area (2) is below 2m. 7. The improved surface flow constructed wetland for treating farmland surface runoff pollutants according to any one of claims 1 to 6, characterized in that floating plants are planted in the final sink catchment area (1). 8. The improved surface flow artificial wetland for treating farmland surface runoff pollutants according to any one of claims 1 to 6, characterized in that: plant floating plants, submerged plants, emergent water plants in the plant absorption area (2) One or more of the plants.