CN101955297A - Landscape-type composite artificial wetland treatment device for eutrophication water body and application thereof - Google Patents

Abstract

The invention discloses a landscape-type composite artificial wetland treatment device for eutrophication water body and application thereof. The composite artificial wetland mainly comprises a wetland wall, a diaphragm wall, a water inlet distribution channel, surface flow and horizontal underflow artificial wetland units which are in upper and lower superposition and serial connection, a middle mixed tank, a water collecting tank, a water inlet/outlet pipeline, and other units. The composite artificial wetland combines the advantages of the surface flow and horizontal underflow artificial wetland, guarantees engineering treatment effect and fulfills the aim of creating wetland landscapes when treating the eutrophication water body according to different dissolved oxygen environments of the surface flow and horizontal underflow artificial wetland, and has the advantages of small occupied area, high treatment efficiency, low construction cost, low possibility of blockage, high operating stability, excellent landscape efficiency, easy popularization and application, and the like.

Description

A landscape-type composite constructed wetland treatment device for eutrophic water body and its application

technical field

The invention relates to the technical field of sewage treatment by composite constructed wetlands, in particular to a landscape-type composite constructed wetland treatment device for eutrophic water bodies and its application.

Background technique

Constructed wetland is a new type of sewage treatment technology developed in the 1970s. After decades of development, this technology has been widely used in the treatment of domestic sewage, surface water, and non-point source pollution. It mainly uses the comprehensive function of wetland plants, microorganisms and soil (or filler) to remove pollutants in sewage. It has the advantages of simple structure, low treatment cost, and landscape effect.

Constructed wetlands are mainly divided into surface flow constructed wetlands and subsurface flow constructed wetlands according to the flow state of treated sewage. Among them, subsurface flow wetlands include horizontal subsurface flow constructed wetlands and vertical subsurface flow constructed wetlands. Although various types of constructed wetlands have their own advantages, they also have some shortcomings. For example, surface flow constructed wetlands have the disadvantages of easy breeding of mosquitoes and flies, limited decontamination ability, and low nitrification ability; horizontal subsurface flow constructed wetlands have the disadvantages of easy blockage and nitrification ability Poor disadvantages; vertical subsurface flow constructed wetlands have the disadvantages of easy blockage, high construction costs and complicated management and maintenance.

In order to overcome the shortcomings of a single type of wetland, current engineering research and application tend to combine different types of wetlands to treat sewage. Chinese patent application 200510047134.X, a landscape-type composite subsurface flow constructed wetland sewage treatment method, Chinese patent ZL200510047935.6, a composite flow constructed wetland and its application system, Chinese patent ZL200610036318.0, integrated composite of vertical flow and horizontal flow The method of constructing wetlands to treat urban sewage is to combine vertical subsurface flow and horizontal subsurface flow constructed wetlands in series, and use the different aerobic and anoxic environments in the two constructed wetlands to remove pollutants such as organic matter and nitrogen and phosphorus. In addition, the matrix is strengthened to enhance the effect of nitrogen and phosphorus removal. Another example is the Chinese patent ZL200510011497.8, the vertical flow-surface flow composite constructed wetland treatment method for domestic sewage, which combines the vertical flow constructed wetland and the surface flow constructed wetland into a composite system to treat domestic sewage, and plants ornamental plants in the vertical flow constructed wetland , Planting aquatic plants, flowers, vegetables or farming fish in surface flow constructed wetlands.

The above combined wetland processes are mainly used to treat sewage with high organic content such as domestic sewage and urban sewage, but there are few related studies on the use of constructed wetland combined processes to treat eutrophic surface water bodies (such as lakes, rivers, reservoirs, etc.).

With the development of society, more and more lakes, rivers, and reservoirs have gradually become eutrophic water bodies due to the discharge of sewage containing a large amount of nitrogen and phosphorus pollutants and initial rainwater, resulting in poor water landscape effects and prone to The "bloom" of cyanobacteria also poses a serious threat to the survival of aquatic plants and animals in the lake. The traditional methods of purifying eutrophic water bodies are water diversion, adding chemical or microbial agents, and using oxygenation facilities or equipment to force oxygenate water bodies, etc. Among them, water diversion and water exchange measures require sufficient and convenient clean water sources as water exchange sources. At the same time, this method has disadvantages such as poor water quality stability and pollution transfer; adding chemical or microbial agents has the disadvantages of large capital investment, easy to repeat water quality, and Secondary pollution and other issues; forced aeration measures have the disadvantages of high energy consumption and high treatment costs.

In addition, compared with natural wetlands, due to the needs of treatment purposes, the structures of constructed wetlands are constructed in an engineering way, especially when using constructed wetlands to treat surface water bodies with landscape requirements, how to improve the landscape of constructed wetlands and minimize The traces of artificialization, in order to coordinate with the surrounding landscape, are also issues that should be considered in the construction of constructed wetlands.

Contents of the invention

Aiming at the deficiencies in the prior art, an object of the present invention is to provide a landscape-type composite constructed wetland treatment device for eutrophic water bodies. The object of the invention is achieved through the following technical solutions: The landscape-type composite constructed wetland treatment device includes a closed wetland wall isolated from the outside. The wetland wall is equipped with a sump, water inlet and distribution channels, a surface flow constructed wetland and a horizontal subsurface flow constructed wetland directly below it, and an intermediate mixing pool. Among them, between the water inlet distribution channel and the surface flow constructed wetland, the composite constructed wetland (the whole composed of the surface flow constructed wetland, the geotextile layer between the two wetland units, and the horizontal subsurface flow constructed wetland unit) and the intermediate mixing pool and sump There is a partition wall between them. The wetland wall adopts mortar block stone or brick wall, the partition wall adopts brick wall or reinforced concrete wall, and the water inlet and distribution channel adopts reinforced concrete structure. The water in and out of the composite constructed wetland treatment device is realized by pipes passing through the wetland wall. Among them, the thickness of the wetland wall is not less than 400mm when mortar blocks are used, and the thickness is not less than 370mm when brick walls are used; the thickness of partition walls is not less than 240mm when brick walls are used, and the thickness is not less than 150mm when reinforced concrete walls are used; The thickness of the partition wall and the bottom plate is 80-100mm. In addition, in order to ensure that the sewage treated by the device of the present invention does not leak through the side of the wall, the brick wall is plastered with cement mortar with a thickness of 15 to 20 mm, and the mortar blocks are jointed with 1:2 cement mortar; For anti-seepage treatment, use clay or undisturbed soil for compaction to ensure that the permeability coefficient is not greater than 10 ^-6 cm/s.

The overall planar size of the composite constructed wetland treatment device of the present invention can be flexibly designed according to the land use conditions. When the aspect ratio of the wetland is not less than 2:1 and the length of the wetland is not more than 100m, no division is required.

The main unit structural features of the device of the present invention are as follows:

Surface flow constructed wetland unit: structurally composed of aquatic plants and plant planting layers from top to bottom. Among them, the aquatic plants are mainly emergent plants and submerged plants, and some floating plants are planted; among them, the emergent plants are one or any combination of lotus, calamus, relihua, iris and aquatic canna; submerged plants It is one or any combination of bitter grass, weed, elodea, and sunflower; the floating-leaf plant is one or any combination of water lily and water lily. The plant planting layer is divided into upper and lower layers, the upper layer is a clay layer, and the lower layer is a fine sand layer (the fineness modulus of the fine sand layer is 2.2-1.6, and Class III natural sand or artificial sand can be used). In addition, the water inlet of the surface flow wetland unit is equipped with a water distribution channel for water distribution, so that the entire wetland bed can be evenly loaded; the water outlet of the surface flow constructed wetland unit uses overflow holes to reduce the occurrence of short flow phenomena. Compared with the conventional surface flow constructed wetland unit, the surface flow constructed wetland unit of the device of the present invention has basically the same structure, the main difference lies in the selection of planting plants in the surface flow constructed wetland, mainly aquatic plants with good ornamental effect. In addition, in order to prevent large suspended matter such as plant residues accumulated in the water during the operation of the surface flow wetland (plant residues that have not been removed in the surface flow wetland and fallen leaves that fall into the wetland around the surrounding area, etc.) A stainless steel wire mesh (with a mesh size of 10-30mm) is installed before the overflow hole at the end of the surface flow wetland, and the grid slag accumulated in front of the mesh is regularly manually removed during operation.

Intermediate mixing pool: The intermediate mixing pool is set at the outlet end of the surface flow constructed wetland, which is the same as the overall height of the composite constructed wetland treatment device of the present invention. The water output from the unit is further uniform.

Horizontal subsurface flow constructed wetland unit: all are filled with gravel layers. Compared with traditional horizontal subsurface flow constructed wetlands, no aquatic plants are planted on the bed, but according to relevant engineering reports and the inventor's test, it still has better water purification Effect.

Water collection pool: The water collection pool is set at the water outlet end of the horizontal subsurface flow constructed wetland. The total height of the water collection pool is the same as that of the composite constructed wetland treatment device of the present invention. keep it steady.

Another object of the present invention is to provide an application of a landscape-type composite constructed wetland treatment device for eutrophic water bodies. The treatment process of this application is as follows:

The eutrophic sewage is pumped or flows through the water inlet pipe of the system into the water inlet and distribution channel, and then enters the surface flow constructed wetland unit after being evenly distributed through the water inlet and distribution channel. The pool flows into the horizontal subsurface flow artificial wetland unit through the water inlet rectification hole at the bottom of the partition wall between the wetland and the intermediate mixing pool. It is discharged from the running outlet pipe through the sump.

Advantage and beneficial effect of the present invention are:

1. The structural characteristics of the device of the present invention make the surface flow constructed wetland and the horizontal subsurface flow constructed wetland vertically combined on a plane basis, and the sewage to be treated is first purified by the upper layer of the surface flow constructed wetland and then enters the lower layer of the horizontal subsurface flow constructed wetland Purify. Due to the water purification effect of the upper surface flow artificial wetland and the filtering effect of the stainless steel wire mesh installed at the end of the surface flow wetland, the probability of clogging during the water purification process of the lower gravel bed is greatly slowed down and effectively prevented, ensuring long-term stable and efficient operation of the entire system . In addition, the composite constructed wetland treatment device composed of this method can greatly save the area compared with the combination of surface flow constructed wetland and horizontal subsurface flow constructed wetland in series in the horizontal direction; Compared with the process combination that slows down or prevents the blockage of the subsurface flow constructed wetland, the investment is obviously saved and the management is convenient;

2. The device of the present invention has the advantages of compact structure, low construction cost, high hydraulic load, and strong operation stability, which effectively solves the problem of wetland system blockage, improves the stable operation time limit of wetlands, reduces secondary pollution problems, and has little impact on the surrounding environment;

3. The combination of the two types of wetlands in the vertical direction effectively reduces the area occupied by the project and saves construction costs;

4. The composite constructed wetland treatment device of the present invention adopts the fully underground type, which reduces artificial traces. At the same time, the construction of the surface flow constructed wetland creates a variety of wetland vegetation landscapes, which improves the relationship between the composite constructed wetland treatment device and the surrounding landscape. coordination;

5. The horizontal subsurface flow constructed wetland in the composite constructed wetland treatment device of the present invention has good thermal insulation due to the sewage flowing below the surface, which reduces the influence of climate on the treatment effect of the wetland;

6. The composite constructed wetland of the present invention can also be used to purify domestic sewage and industrial wastewater with certain pretreatment measures.

Description of drawings

Fig. 1 is a schematic plan view of a landscape-type composite constructed wetland treatment device for eutrophic water bodies in a specific embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view in the direction of sewage treatment of a landscape-type composite constructed wetland treatment device for eutrophic water bodies according to the present invention.

Fig. 3 is a schematic cross-sectional view of the opening of the partition wall between the wetland and the intermediate mixing tank in the device of the present invention.

Reference signs are explained as follows: 1-system water inlet pipe, 2-water inlet and distribution channel, 3-water inlet and distribution channel and surface flow artificial wetland partition wall, 4-water distribution hole, 5-aquatic plants, 6-surface flow artificial wetland outlet Stainless steel wire mesh, 7-wetland and intermediate mixing tank partition wall, 8-surface flow artificial wetland outlet overflow hole, 9-intermediate mixing tank, 10-intermediate mixing tank cover, 11-wetland wall, 12-intermediate mixing tank Gravel layer, 13-water inlet rectification hole, 14-clay layer, 15-fine sand layer, 16-geotextile layer, 17-horizontal subsurface flow artificial wetland gravel layer, 18-wetland and sump partition wall, 19-water outlet rectification hole , 20-water collecting tank, 21-water collecting tank gravel layer, 22-water collecting tank cover plate, 23-running outlet pipe, 24-venting pipe.

Detailed ways

The composition structure, working principle and application method of the device of the present invention will be described in detail below in conjunction with the accompanying drawings.

The landscape-type composite artificial wetland treatment device for eutrophic water body of the present invention is built on the bank of a river, lake or reservoir to be treated, and the treated water is eutrophic water body. The device of the invention makes full use of the respective advantages of the surface flow and the horizontal subsurface flow artificial wetland, and while purifying and treating the eutrophic water body, it also improves the surrounding landscape of the wetland.

As shown in Figure 1, a landscape-type composite constructed wetland treatment device for eutrophic water body includes a closed wetland wall 11 isolated from the outside, the top surface of the wetland wall 11 is 0.2m higher than the surrounding ground, and the wetland wall 11 It is equipped with a sump 20, water inlet and distribution channel 2, surface flow constructed wetland and the horizontal subsurface flow constructed wetland directly below it, and an intermediate mixing pool 9. Among them, between the water inlet and distribution channel 2 and the surface flow constructed wetland, the composite constructed wetland (the whole composed of the surface flow artificial wetland, the geotextile layer 16 between the two wetland units, and the horizontal subsurface flow artificial wetland unit) and the intermediate mixing pool 9 and the sump 20 are provided with partition walls. In addition, at the end of the surface flow constructed wetland, there is also a surface flow constructed wetland outlet stainless steel wire mesh 6 before the outlet overflow hole 8 of the surface flow constructed wetland.

The water in and out of the compound constructed wetland treatment device of the present invention (system water inlet pipe 1, running water outlet pipe 23 and vent pipe 24) are all realized by pipes passing through the wetland wall 11, surface flow constructed wetland unit, water inlet and distribution channel 2 The sum of the areas is the same as the area of the horizontal subsurface flow constructed wetland unit.

The geotextile layer 16 is laid in two layers, the anti-seepage coefficient of the geotextile is ≤1.0×10 ⁻¹⁰ cm/s, and the thickness of a single layer of geotextile is 1˜3 mm.

The surface flow artificial wetland outlet water stainless steel wire mesh 6 meshes 10-30mm are fixed on the plant planting layer of the surface flow artificial wetland by wooden stakes, the distance between the wooden piles is 8-15m, and the height of the stainless steel wire mesh is not less than the surface flow artificial wetland The sum of plant planting layer and water depth.

In order to achieve the purpose of uniform water distribution in both the surface flow and horizontal subsurface flow constructed wetland units, water distribution and rectification facilities are provided for the inflow and outflow of the surface flow constructed wetland and horizontal subsurface flow constructed wetland units.

As shown in Figure 2, the device of the present invention is seen from the direction perpendicular to the treated sewage, starting from the water inlet of the system, followed by the wetland wall 11 at one end, the sump 20, the partition wall 18 between the wetland and the sump, and the inlet in the horizontal direction. Water distribution canal 2, artificial wetland with combined upper and lower vertical surface flow and horizontal subsurface flow, wetland and intermediate mixing pool partition wall 7, intermediate mixing pool 9 and wetland wall 11 at the other end.

Combining with Fig. 2 and the whole flow of treated sewage from water inlet to water outlet, the specific structure and positional relationship of the above parts are described as follows: First, the system water inlet pipe 1 passes through the wetland wall 11, and the sump 20 and the wetland are separated from the sump. The wall 18 introduces the eutrophic sewage to be treated into the water inlet distribution channel 2 arranged at the water inlet of the surface flow constructed wetland unit, and the sewage to be treated passes through the water inlet distribution channel 2, and then passes through the water inlet distribution channel and the surface flow constructed wetland The water distribution hole 4 at the bottom of the partition wall 3 (the hole diameter is 40-80mm, and the distance between the centers of two adjacent holes is 0.8-1.2m) flows into the surface flow constructed wetland unit. The surface flow constructed wetland unit consists of 5 aquatic plants (aquatic plants are planted with lotus, water lily, bitter grass and weed, and the planting density is 2-6 plants/10m ² , 1-4 plants/10m ² , 10-30 plants/m ² and 10-30 plants/m ² ) and the plant planting layer (the plant planting layer is divided into upper and lower layers, the upper layer is clay layer 14 with a height of 0.2-0.5m, the lower layer is fine sand layer 15 with a height of 0.1-0.3m, fineness Modulus 2.2-1.6, using Class III artificial sand), the height of the planting layer of this unit is 0.3-0.8m, and the water depth is 0.4-0.5m. Surface flow wetland water surface height) is not less than 0.3m. All horizontal subsurface flow constructed wetland units are filled with horizontal subsurface flow constructed wetland gravel layer 17 (0.6-1.0m in height, 15-25mm in particle size). The total height of the wetland wall in the compound constructed wetland (surface flow constructed wetland, the geotextile layer 16 between two wetland units and the horizontal subsurface flow constructed wetland unit) is controlled at 1.5-2.5m.

In order to ensure the series operation of the surface flow constructed wetland and the horizontal subsurface flow constructed wetland unit, in addition to setting the water inlet distribution channel 2 at the water inlet, an intermediate mixing pool 9 is also set at the water outlet of the surface flow constructed wetland unit, and the water outlet of the horizontal subsurface flow constructed wetland A sump 20 is set up, and the sewage treated by the surface flow constructed wetland passes through the wetland and the surface flow constructed wetland overflow hole 8 (square hole, size 120×120mm, the center distance between two adjacent holes is 0.8 ~1.2m) into the middle mixing pool 9. The height above the planting layer of the water inlet distribution channel 2 and the surface flow constructed wetland unit (that is, the sum of the planting water depth of the surface flow constructed wetland unit and the superheight of the wall top) is the same, and the height of the wall top of the middle mixing pool 9 and the sump pool 20 should be The water surface height of the specific surface flow wetland shall not be less than 0.3m. At the same time, the tops of the intermediate mixing pool 9 and the sump 20 are provided with cover plates, which are respectively the intermediate mixing pool cover plate 10 and the sump pool cover plate 22, and the middle mixing pool gravel layer 12 (height 0.6～1.0m, granular 25-50 mm in diameter) and the gravel layer 21 (height 0.6-1.0 m, particle size 25-50 mm) in the sump pool. After the sewage is further treated in the intermediate mixing tank 9, it passes through the wetland and the water inlet rectification hole at the lower end of the intermediate mixing tank partition wall 7 13 (square hole, size 240×240mm, the distance between the centers of two adjacent holes is 1.6-2.4m) flows into the gravel layer 17 of the horizontal subsurface flow artificial wetland, and then passes through the water outlet rectification hole 19 (square hole, the size of which is 240×240mm, and the distance between the centers of two adjacent holes is 1.6-2.4m) and flows into the sump 20, after being purified by the gravel layer 21 of the sump 20 at the bottom of the sump 20, the water outlet pipe 23 connected with the sump 20 will finally Treated water discharge unit.

In the above technical scheme, except that the water distribution hole 4 is a pre-embedded plastic round hole for water distribution, the other overflow and rectification holes are square holes reserved in the wall. The length of the water inlet distribution channel and the surface flow artificial wetland partition wall 3 and the wetland and the sump tank wall 18 are the same, and the length of the wetland and the intermediate mixing pool wall 7 is not less than the length of the water inlet distribution channel 2 . The number of holes for water distribution hole 4, water inlet rectification hole 13, and water outlet rectification hole 19 is determined according to the length of the partition wall, on the surface flow artificial wetland partition wall 3, wetland and sump partition wall 18, and wetland and intermediate mixing pool partition wall 7 Open holes in the full section perpendicular to the water flow. The opening relationship between the wetland and the intermediate mixing pool partition wall 7, the surface flow artificial wetland outlet overflow hole 8 and the water inlet rectification hole 13 is shown in Figure 3, and the center of the two adjacent holes of the surface flow artificial wetland outlet overflow hole 8 The spacing is half of the center spacing between two adjacent holes of the water inlet rectifying hole 13 . The opening size of the water inlet rectification hole 13 and the water outlet rectification hole 19 are the same and kept at the same height.

The water in and out of the device of the present invention adopts pipes: the system water inlet pipe 1 (pipe diameter DN100～DN200, PVC-U pipe, the elevation of the bottom of the pipe is higher than that of the water inlet and distribution channel 2, and the water surface elevation is not less than 0.1m, passing through the wetland wall 11 1. The sump 20 and the wetland and sump partition wall 18 enter the water inlet and distribution channel 2; the outlet pipe has a running outlet pipe 23 (diameter DN200～DN300, PVC-U pipe, the elevation of the bottom of the pipe is lower than the water level of the sump not more than 0.3 m) and emptying pipe 24 (pipe diameter DN300～DN500, PVC-U pipe, pipeline is installed at the bottom of the sump).Wherein, the running water outlet pipe 23 is the water outlet pipe when the composite constructed wetland of the present invention normally operates, and the emptying pipe 24 is only opened during maintenance and overhaul, and the running water outlet pipe 23 and the vent pipe 24 all pass through the wetland wall 11 and are connected to the sump 20 .

When the composite constructed wetland treatment device of the present invention is in operation, the eutrophic sewage is pumped into the water inlet distribution channel 2 by the submersible pump through the system water inlet pipe 1 (if conditions permit, the water body to be treated can also be allowed to flow into the water inlet distribution channel 2 ), and enter the surface flow constructed wetland unit after uniform distribution of water through the water distribution hole 4. Due to the comprehensive effect of the plant planting layer and aquatic plants 5 of the surface flow constructed wetland unit, most of the suspended solids in the sewage are intercepted and adsorbed; at the same time, due to the good reoxygenation capacity of the surface flow constructed wetland, some organic matter is absorbed by microorganisms and Absorbed and utilized by plant roots, part of N and P are absorbed by microorganisms and plants as nutrients, and part is removed through nitrification and denitrification. The sewage that has been preliminarily purified by the surface flow constructed wetland unit flows into the intermediate mixing pool 9 through the surface flow constructed wetland outlet overflow hole 8, and flows into the horizontal subsurface flow constructed wetland unit through the gravel layer 12 of the intermediate mixing pool through the water inlet rectification hole 13. After the system was stabilized, a large number of microorganisms grew on the surface of the gravel layer 17 of the horizontal subsurface flow constructed wetland, and formed a biofilm. The role of further purification. The sewage purified by the horizontal subsurface flow constructed wetland unit flows into the sump 20 through the water outlet rectification hole 19, and is discharged from the running outlet pipe 23 after passing through the gravel layer 21 of the sump.

The device of the present invention is applied to a water purification project of a eutrophic lake in the urban area of Wuhan City, and the daily water treatment volume is 3000m ³ . Its plan view is shown in Figure 1.

Design Parameters:

Covered area: 2960m ² (the wetland is transformed from the original lotus pond on a small island in the lake, with an irregular sickle shape), divided into upper and lower floors, undivided, the wetland wall 11 is a mortar block stone structure, and the water inlet The partition wall 3 between the distribution channel 2 and the surface flow artificial wetland, the partition wall 7 between the wetland and the intermediate mixing pool, and the partition wall 18 between the wetland and the sump are all made of brick structure cement plaster, and the water inlet distribution channel 2 is a reinforced concrete structure.

Inlet and distribution channel 2: net width of the channel is 300mm, water depth is 0.3m, diameter of water distribution hole 4 is 40-80mm, length of water inlet and distribution channel is 40m, and 39 water distribution holes 4 are set at the bottom of water inlet and distribution channel 2, etc. The distance between the centers of adjacent water distribution holes is 1m.

Constructed wetland unit with surface flow: the total depth is 1.1m, of which, the water depth is 0.4m, the water surface of the pool body is super high 0.3m, the thickness of the clay layer 14 and the fine sand layer 15 are 300mm and 100mm respectively, and the aquatic plants 5 are lotus, water lily, The planting densities of Erythrina fragrans and Smilax chinensis are 3 plants/10m ² , 2 plants/10m ² , 15 plants/m ² , and 15 plants/m ² . The outlet overflow hole 8 of the surface flow constructed wetland is a square hole with a size of 120×120mm, and the distance between the centers of two adjacent holes is 1000mm.

Outlet stainless steel wire mesh 6 of the surface flow constructed wetland: its two ends are connected with the wetland wall 11, the mesh is 15mm, fixed on the bottom of the clay layer 14 of the surface flow constructed wetland by four wooden stakes, the height is 1.0m, and the length is 45m.

Geotextile layer 16: Two layers of geotextile are laid, the anti-seepage coefficient of geotextile is ≤1.0×10 ^-10 cm/s, and the thickness of a single layer is 1-3mm.

Intermediate mixing tank 9: the total depth is 1.9m, the net width is 800mm, the cover plate 10 of the intermediate mixing tank covered on the top is a plastic grid plate, the thickness of the gravel layer 12 of the intermediate mixing tank laid on the bottom is 800mm, and the particle size is 25-50mm.

Horizontal subsurface flow constructed wetland unit: the total depth is 0.8m, the horizontal subsurface flow constructed wetland gravel layer 17 is 800mm thick, and the gravel particle size is 15-25mm. The water inlet rectification hole 13 and the water outlet rectification hole 19 of the horizontal subsurface flow constructed wetland are both square holes with a size of 240×240mm, and the distance between the centers of two adjacent holes is 2000mm.

The sump 20: the total depth is 1.9m, the clear width is 800mm, the sump cover plate 22 covered on the top is a plastic grid plate, the thickness of the sump gravel layer 21 laid on the bottom is 800mm, and the particle size is 25-50mm.

Inlet and outlet pipes: PVC-U pipes are used, the system inlet pipe 1 is DN100, the running outlet pipe 23 is DN200, and the vent pipe 24 is DN300.

Operation mode: continuous operation, the hydraulic retention time is 23h.

After 2 years of operation of the composite constructed wetland treatment device, the treatment effect is shown in Table 1.

Table 1 Comparison table of water quality operation status of composite constructed wetland treatment device (annual average)

water quality pH COD _cr COD _Mn BOD ₅ NH ₃ -N TN TP SS water ingress 8.1 85.0 20.3 7.9 3.5 5.9 0.41 43.0 out of water 8.0 29.3 6.5 3.8 1.8 2.0 0.19 4.0

On the central island of the lake, there is another lateral horizontal subsurface flow constructed wetland. This wetland operates in parallel with the composite constructed wetland device of the present invention. The daily water treatment volume is the same, both of which are 3000m ³ /d. The main technical parameters of this wetland are:

It covers an area of 2100m ² (the shape is irregular fan-shaped), and it is divided into 3 grids to run in parallel. Each grid is planted with canna, zalihua and cattail. The filler is gravel with a total thickness of 700mm.

After 2 years of stable operation of the lateral horizontal subsurface flow constructed wetland, the comparison of its annual average inflow and outflow water quality with that of the composite constructed wetland of the present invention is shown in Table 2.

Table 2 Comparison list of influent and effluent water quality between the composite constructed wetland of the present invention and the lateral subsurface flow constructed wetland

Moreover, after 2 years of continuous operation, the water level of the water inlet of the lateral subsurface flow constructed wetland is 0.12m higher than the initial water depth (accounting for 15% of the water depth of the water inlet), and the flow rate of the water outlet is reduced by 10% compared with the initial one. The composite constructed wetland treatment device of the present invention The water level of the water inlet is 0.03m high (accounting for 4% of the water depth of the water inlet), and the flow rate of the water outlet is increased by 10% compared with the initial one. It shows that after 2 years of continuous operation, a certain degree of clogging has occurred in the lateral subsurface flow constructed wetland, while the composite constructed wetland treatment device of the present invention is still unobstructed and has no sign of clogging.

Claims (10)

1. the landscape type combined artificial wetland treatment unit of an eutrophication water, it is characterized in that: comprise wetland body of wall (11) with the isolated sealing in the outside, be located at water collecting basin (20) in the wetland body of wall (11), water inlet distributing flue (2), superpose placed in-line surface current artificial wetland and horizontal drowned flow artificial wet land, middle mixing pit (9) and the inlet and outlet pipe lines that passes the wetland body of wall (11) of water collecting basin (20) one sides up and down;

Described inlet and outlet pipe lines has system's water inlet pipe (1), operation rising pipe (23) and blow-down pipe (24), wherein system's water inlet pipe (1) passes wetland body of wall (11), water collecting basin (20) links to each other with water inlet distributing flue (2) with water collecting basin partition wall (18) with wetland, and operation rising pipe (23) all passes wetland body of wall (11) with blow-down pipe (24) and links to each other with water collecting basin (20);

Link to each other with surface current artificial wetland's partition wall (3) by the water inlet distributing flue between described water inlet distributing flue (2) and the surface current artificial wetland;

Described superpose up and down placed in-line surface current artificial wetland and horizontal drowned flow artificial wet land whole with middle mixing pit (9), water collecting basin (20) between link to each other with water collecting basin partition wall (18) with middle mixing pit partition wall (7), wetland by wetland respectively;

Link to each other by geotechnological layer of cloth (16) between described surface current artificial wetland and the horizontal drowned flow artificial wet land.

2. the landscape type combined artificial wetland treatment unit of a kind of eutrophication water according to claim 1, it is characterized in that: described surface current artificial wetland is made up of waterplant (5) and plant growing layer, waterplant (5) is based on emergent and submerged plant, plant the part floatingleaved plant again, described plant growing layer divides two-layer up and down, the upper strata is clay seam (14), and lower floor is fine sand layer (15).

3. the landscape type combined artificial wetland treatment unit of a kind of eutrophication water according to claim 1 is characterized in that: mixing pit gravel bed (12) and water collecting basin gravel bed (21) in the middle of the bottom of mixing pit (9) and water collecting basin (20) is equipped with respectively in the middle of described.

4. the landscape type combined artificial wetland treatment unit of a kind of eutrophication water according to claim 1, it is characterized in that: described horizontal drowned flow artificial wet land is all filled by horizontal drowned flow artificial wet land gravel bed (17).

5. the landscape type combined artificial wetland treatment unit of a kind of eutrophication water according to claim 2 is characterized in that: described emergent is lotus, calamus, a kind of or arbitrary combination in power flower, iris and the aquatic Canna generalis Bailey again; Submerged plant is a kind of or arbitrary combination in eel grass, water caltrop, waterweed and the p.malaianus; Floatingleaved plant is a kind of or arbitrary combination in water lily and the floating heart.

6. according to the landscape type combined artificial wetland treatment unit of arbitrary described a kind of eutrophication water among the claim 1-5, it is characterized in that: described water inlet distributing flue and surface current artificial wetland's partition wall (3) bottom are provided with distributing hole (4).

7. according to the landscape type combined artificial wetland treatment unit of arbitrary described a kind of eutrophication water among the claim 1-5, it is characterized in that: the upper end of described wetland and middle mixing pit partition wall (7) is provided with surface current artificial wetland's water outlet overflow weir (8), is provided with surface current artificial wetland's water outlet Stainless Steel Cloth (6) before at surface current artificial wetland's water outlet overflow weir (8) of described surface current artificial wetland's end.

8. according to the landscape type combined artificial wetland treatment unit of arbitrary described a kind of eutrophication water among the claim 1-5, it is characterized in that: the bottom of described wetland and middle mixing pit partition wall (7) and wetland and water collecting basin partition wall (18) is respectively equipped with the water inlet rectification hole (13) and the water outlet rectification hole (19) of horizontal drowned flow artificial wet land.

9. according to the landscape type combined artificial wetland treatment unit of arbitrary described a kind of eutrophication water among the claim 1-5, it is characterized in that: described wetland body of wall (11) adopts cemented rock or brick wall;

Described water inlet distributing flue and surface current artificial wetland's partition wall (3), wetland and middle mixing pit partition wall (7) and wetland and water collecting basin partition wall (18) all adopt brick wall or reinforced concrete wall;

Described water inlet distributing flue (2) adopts reinforced concrete structure.

10. the application of the landscape type combined artificial wetland treatment unit of a kind of eutrophication water as claimed in claim 1 in handling eutrophication water.

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