阅读说明：本技术 螺旋式复合人工湿地系统 (Spiral composite artificial wetland system ) 是由 韩延成 周欣悦 王月蕾 方攀博 陈思涵 黄兆虎 王栋 于 2021-08-05 设计创作，主要内容包括：本发明公开了一种螺旋式复合人工湿地系统,包括主撑体和设置在主撑体上的螺旋状阶梯支撑架,所述螺旋状阶梯支撑架在空间上从上到下设置若干个串联连接的人工湿地反应器,所述人工湿地反应器包括潜流人工湿地和表流人工湿地。本发明能够在高效净化污水的基础上提高了空间利用率、节约了土地,同时具有环境美化的功能,对在土地紧张的情况下建设人工湿地将产生积极意义。(The invention discloses a spiral composite artificial wetland system, which comprises a main support body and a spiral stepped support frame arranged on the main support body, wherein a plurality of artificial wetland reactors connected in series are arranged on the spiral stepped support frame from top to bottom in space, and each artificial wetland reactor comprises an undercurrent artificial wetland and a surface current artificial wetland. The invention can improve the space utilization rate and save the land on the basis of efficiently purifying the sewage, has the function of beautifying the environment and has positive significance for building the artificial wetland under the condition of short land.)

1. The utility model provides a spiral compound constructed wetland system, characterized by includes the main support body and sets up the heliciform ladder support frame on the main support body, heliciform ladder support frame sets up a plurality of series connection's constructed wetland reactor from the top down in the space, the constructed wetland reactor includes undercurrent constructed wetland and surface current constructed wetland's combination.

2. The spiral-type composite artificial wetland system according to claim 1, wherein the subsurface flow artificial wetland and the surface flow artificial wetland are alternately connected in series from the subsurface flow artificial wetland in a number ratio of 1: n, wherein n is 1, 2, 3 or 4.

3. The spiral-type composite artificial wetland system according to claim 1, wherein the subsurface flow artificial wetland and the surface flow artificial wetland are constructed in a manner that n: 1, and alternately connecting in series from the surface flow artificial wetland, wherein n is 1, 2, 3 or 4.

4. The spiral-type composite artificial wetland system as claimed in claim 1, wherein the subsurface flow artificial wetland comprises at least a soil layer, a zeolite layer and a gravel layer, wetland plants are planted above the soil layer, a first water heating pipeline is arranged in the soil layer, a second water heating pipeline is arranged on the zeolite layer, a third water heating pipeline is arranged on the gravel layer, and the first water heating pipeline, the second water heating pipeline and the third water heating pipeline are connected end to end.

5. The spiral type composite artificial wetland system as claimed in claim 1, wherein the surface flow artificial wetland comprises a soil layer and a zeolite layer, wetland plants are planted above the soil layer, a first water heating pipeline is arranged in the soil layer, a second water heating pipeline is arranged in the zeolite layer, and the first water heating pipeline and the second water heating pipeline are connected end to end.

6. The spiral-type composite artificial wetland system according to claim 1, wherein the water inlet of the artificial wetland reactor is positioned at the upper part of the artificial wetland reactor, the water outlet is positioned at the lower part of the artificial wetland reactor, and the water inlet and the water outlet are respectively positioned at two sides of the artificial wetland reactor.

7. The spiral-type composite artificial wetland system according to any one of claims 1 to 6, wherein the water outlet of the previous artificial wetland reactor in the two adjacent artificial wetland reactors is communicated with the water inlet of the next artificial wetland reactor through a water outlet aeration pipe; the water flow of the artificial wetland enters from the water inlet of the first artificial wetland, flows out from the water outlet, and the effluent enters the next artificial wetland after being subjected to sufficient water drop aeration through the water outlet aeration pipe until reaching the last artificial wetland.

8. The spiral composite artificial wetland system as claimed in claim 7, wherein the front 1/3 part of the water outlet aeration pipe is a non-porous pipe, the rear 2/3 part of the water outlet aeration pipe is a strainer pipe with an open hole on the pipe wall, and water drops from the strainer pipe section to the next artificial wetland; the non-porous pipe section part is connected with the water outlet of the previous artificial wetland, and the water filter pipe with the hole on the pipe wall is connected with the water inlet of the next artificial wetland after being connected with the non-porous pipe section.

9. The spiral-type composite artificial wetland system according to claim 7, wherein the water heating pipelines of the artificial wetland reactor are made of heat conducting materials, and the water pipe spacing of the water heating pipelines at the upper layer is smaller than that of the water heating pipelines at the lower layer.

10. The spiral-type composite constructed wetland system of claim 7, wherein the wetland plants are calamus plants.

Technical Field

The invention relates to a spiral composite artificial wetland system, in particular to a novel spiral composite artificial wetland system which fully utilizes space, and belongs to the technical field of sewage treatment.

Background

At present, the wastewater treatment in China mainly depends on a sewage treatment plant, and the operation cost is high and the management and operation are complex. The artificial wetland is constructed by simulating a natural wetland, and can treat almost all types of wastewater, such as domestic sewage, rainwater runoff, agricultural runoff, industrial discharge, polluted river water and the like, by utilizing an engineered wetland system for purifying the wastewater by utilizing the synergistic action of soil, matrix, plants and microorganisms. The artificial wetland has the functions of wastewater treatment, landscape, ecological protection, water resource recycling, regional climate regulation, education and entertainment.

Conventional artificial wetlands generally require a large amount of area. However, land resources in many areas of our country, whether cultivated land or commercial land, are increasingly strained based on the enormous population base and the rapidly expanding urban scale. On one hand, although the total amount of the cultivated land area in China is large, the cultivated land area per capita is not equal to the average level of the world, so the red line of the cultivated land cannot be crossed. On the other hand, cities with high population density like Beijing and Shanghai are suitable for building artificial wetlands, but the land is less and less, the areas are just places with high sewage discharge amount, the total discharge amount of the waste water in the Shanghai in 2017 is up to 21.20 hundred million tons, and the total discharge amount is almost the annual discharge amount of the whole provinces in Anhui province.

Therefore, how to construct an artificial wetland for efficiently treating sewage on a limited land area is a problem to be solved. In addition, a large amount of roof and overpass rainwater in cities and towns are important factors for aggravating water pollution, and how to fully utilize the water heads of the high-rise buildings and solve the water flow power of the constructed wetland is also a problem faced by people.

Disclosure of Invention

In order to solve the problems, the invention provides a spiral composite artificial wetland system which can improve the space utilization rate, save the land and simultaneously has the function of beautifying the environment.

The technical scheme adopted for solving the technical problems is as follows:

the spiral composite artificial wetland system provided by the embodiment of the invention comprises a main support body and a spiral stepped support frame arranged on the main support body, wherein a plurality of artificial wetland reactors connected in series are arranged on the spiral stepped support frame from top to bottom in space, and each artificial wetland reactor comprises various combinations of subsurface flow artificial wetland and surface flow artificial wetland.

As a possible implementation manner of the embodiment, the subsurface flow constructed wetlands and the surface flow constructed wetlands are alternately connected in series from the subsurface flow constructed wetlands in a number ratio of 1: n, wherein n is 1, 2, 3 or 4.

As a possible implementation manner of this embodiment, the subsurface flow constructed wetland and the surface flow constructed wetland are divided into n: 1, and alternately connecting in series from the surface flow artificial wetland, wherein n is 1, 2, 3 or 4.

As a possible implementation manner of this embodiment, the subsurface flow constructed wetland at least includes a soil layer, a zeolite layer and a gravel layer, wetland plants are planted above the soil layer, a first water heating pipeline is arranged in the soil layer, a second water heating pipeline is arranged on the zeolite layer, a third water heating pipeline is arranged on the gravel layer, and the first water heating pipeline, the second water heating pipeline and the third water heating pipeline are connected end to end.

As a possible implementation manner of this embodiment, the surface flow constructed wetland includes a soil layer and a zeolite layer, wetland plants are planted above the soil layer, a first water heating pipeline is arranged in the soil layer, a second water heating pipeline is arranged on the zeolite layer, and the first water heating pipeline and the second water heating pipeline are connected end to end.

As a possible implementation manner of this embodiment, the water inlet of the artificial wetland reactor is located at the upper part of the artificial wetland reactor, the water outlet is located at the lower part of the artificial wetland reactor, and the water inlet and the water outlet are respectively located at two sides of the artificial wetland reactor.

As a possible implementation manner of this embodiment, the water outlet of the previous artificial wetland reactor in the two adjacent artificial wetland reactors is communicated with the water inlet of the next artificial wetland reactor through the water outlet aeration pipe; the water flow of the artificial wetland enters from the water inlet of the first artificial wetland, flows out from the water outlet, and the effluent enters the next artificial wetland after being subjected to sufficient water drop aeration through the water outlet aeration pipe until reaching the last artificial wetland. The structure makes full use of natural water head, reduces the pumping link, can make full drop aeration, and is beneficial to improving the concentration of dissolved oxygen and the removal efficiency of pollutants.

As a possible implementation manner of this embodiment, the front end 1/3 part of the water outlet aeration pipe is a non-porous pipe, the rear part 2/3 part of the water outlet aeration pipe is a strainer pipe with an open hole on the pipe wall, and water drops from the strainer pipe section to the next artificial wetland; the non-porous pipe section part is connected with the water outlet of the previous artificial wetland, and the water filter pipe with the hole on the pipe wall is connected with the water inlet of the next artificial wetland after being connected with the non-porous pipe section, so that the design and the falling process greatly increase the contact area of the water body and the atmosphere, the aeration is sufficient, and the improvement of the concentration of dissolved oxygen and the removal efficiency of pollutants is facilitated.

As a possible implementation manner of this embodiment, the water heating pipes of the artificial wetland reactor are made of a heat conducting material, and the interval between the water pipes of the water heating pipes on the upper layer is smaller than that of the water heating pipes on the lower layer.

As a possible implementation manner of this embodiment, the wetland plant is a calamus plant.

The technical scheme of the embodiment of the invention has the following beneficial effects:

compared with the existing artificial wetland, the novel spiral composite artificial wetland system for making full use of space is large in occupied area and not suitable for urban construction, the artificial wetland is arranged in a spiral space ladder type structure, and compared with the traditional wetland, the spiral composite artificial wetland system for making full use of space has the effect of greatly saving land and can be widely applied to urban land shortage areas.

The invention is formed by connecting a plurality of small wetland reactors in series from top to bottom in space, and the series connection mode of the subsurface flow constructed wetland and the surface flow constructed wetland can be flexibly combined, different composite wetland types can be formed according to local conditions, and the composite wetland can be a plurality of combination modes such as a subsurface flow-surface flow-subsurface flow mode, a surface flow-subsurface flow-surface flow mode or a subsurface flow-surface flow mode, and the like, thereby improving the effective method of the purification efficiency of the constructed wetland and fully playing the advantages of the two constructed wetlands.

Compared with the traditional wetland reactor which is rectangular, the spiral composite artificial wetland has good ornamental value.

Compared with the conventional artificial wetland, the spiral stepped type composite artificial wetland designed by the invention can realize the sewage transfer by pumping water, and can make the sewage fall from a high place compared with the common composite wetland, thereby solving the problem of sewage transfer and omitting the pumping link.

The artificial wetland with the spiral stepped structure has a high water head, has sufficient water drop aeration, can increase the content of dissolved oxygen in sewage, and is favorable for removing pollutants in water.

The water flow of the artificial wetland enters from the water inlet of the first-stage artificial wetland, flows out from the water outlet, and enters the second-stage artificial wetland after sufficient water drop aeration until reaching the last artificial wetland. The structure makes full use of natural water head, reduces the pumping link, can make full drop aeration, and is beneficial to improving the concentration of dissolved oxygen and the removal efficiency of pollutants.

The invention connects the aeration pipe of the effluent at the outlet port of the artificial wetland, the aeration pipe of the effluent adopts the non-porous pipe 1/3 long, 2/3 long adopts the water filter pipe with open pore of pipe wall, the water drops from the water filter pipe section; the design that the non-porous pipe section is connected with the wetland water outlet and the perforated strainer pipe is connected with the non-porous pipe section, and the falling process greatly increases the contact area of the water body and the atmosphere, is sufficient in aeration and is beneficial to improving the concentration of dissolved oxygen and the removal efficiency of pollutants.

The invention can improve the space utilization rate and save the land on the basis of efficiently purifying the sewage, has the function of beautifying the environment and has positive significance for building the artificial wetland under the condition of short land.

Description of the drawings:

fig. 1 is a structural view illustrating a spiral type complex constructed wetland system according to an exemplary embodiment;

fig. 2 is a schematic diagram illustrating an on-site experimental structure of a spiral-type complex constructed wetland system according to an exemplary embodiment;

fig. 3 is a schematic structural diagram of a drop aerator pipe with a non-porous pipe at the front end 1/3 part and an open pore at the rear end 2/3 part;

fig. 4 is a schematic view of a spiral stepped wetland system made of hills and soil packets according to an exemplary embodiment;

fig. 5 is a schematic structural view of a general composite constructed wetland in the prior art;

fig. 6 is a relation diagram of the occupied area of the step-type artificial wetland and the novel spiral-type composite artificial wetland constructed by the common composite artificial wetland and the attached side slope of the invention and the artificial wetland.

Detailed Description

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

in order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and procedures are omitted so as to not unnecessarily limit the invention.

Fig. 1 is a structural view illustrating a spiral-type complex constructed wetland system according to an exemplary embodiment. The spiral composite artificial wetland system provided by the embodiment of the invention comprises a main support body 1 and spiral stepped support frames b1, b2, b3 and … bn … which are arranged on the main support body, wherein a plurality of artificial wetland reactors connected in series are arranged on the spiral stepped support frames from top to bottom in space, and each artificial wetland reactor comprises an underflow artificial wetland and an overflow artificial wetland.

As a possible implementation manner of the embodiment, the subsurface flow constructed wetlands and the surface flow constructed wetlands are alternately connected in series from the subsurface flow constructed wetlands in a number ratio of 1: n, wherein n is 1, 2, 3 or 4.

As shown in fig. 2, as one possible implementation manner of this embodiment, the subsurface constructed wetlands and the surface constructed wetlands are alternately connected in series at a ratio of 1:1 from the subsurface constructed wetlands, that is, the top-stage constructed wetland B1 is the surface constructed wetland B1, the second-stage constructed wetland B2 is the subsurface constructed wetland B2, and the third-stage constructed wetland B3 is the surface constructed wetland B3, and are connected in sequence. The alternate combination of the subsurface flow constructed wetland and the surface flow constructed wetland is an effective method for improving the purification efficiency of the constructed wetland, and can fully exert the advantages of the two constructed wetlands. When the content of dissolved oxygen in water is high, the method is favorable for growth of aerobic bacteria and plants, and can improve the removal rate of COD, in addition, the aerobic environment is favorable for the implementation of nitration reaction, and can obviously improve the conversion rate of NH4+ -N and the purification efficiency of NH4+ -N.

In one possible implementation manner of the embodiment, the subsurface flow constructed wetlands and the surface flow constructed wetlands are alternately connected in series at a ratio of 2:1 from the subsurface flow constructed wetlands.

As a possible implementation manner of this embodiment, the subsurface flow constructed wetland and the surface flow constructed wetland are divided into n: 1, and alternately connecting in series from the surface flow artificial wetland, wherein n is 1, 2, 3 or 4.

As one possible implementation manner of this embodiment, the subsurface flow constructed wetland and the surface flow constructed wetland are divided into 1:1 and alternately connected in series from the surface flow artificial wetland.

As one possible implementation manner of this embodiment, the subsurface flow constructed wetland and the surface flow constructed wetland are divided into 1: 2 and alternately connected in series from the surface flow artificial wetland.

The invention is formed by connecting a plurality of small wetland reactors in series from top to bottom in space, the series connection mode can be flexibly combined, and different composite wetland types can be formed according to local conditions.

The first type is an underflow-surface flow-underflow combined mode, as shown in fig. 2, namely the uppermost-stage wetland is a surface flow artificial wetland B1, the second stage is a surface flow artificial wetland B2, and the third stage is a surface flow artificial wetland B3, which are connected in sequence. The second type is a surface flow-subsurface flow-surface flow combined mode, namely, the top-level wetland is a subsurface flow constructed wetland, the second level is a surface flow constructed wetland, and the third level is a subsurface flow constructed wetland which are connected in sequence. The third type is an underflow-surface flow combined mode, namely two underflow wetlands are connected with one surface flow wetland. The fourth combination mode is a surface flow-subsurface flow combination mode, namely two surface flows are connected with one subsurface flow wetland. The alternate combination of the subsurface constructed wetland and the surface flow constructed wetland of the combined spiral wetland is an effective method for improving the purification efficiency of the constructed wetland, and can fully exert the advantages of the two constructed wetlands. When the content of dissolved oxygen in water is high, the method is favorable for growth of aerobic bacteria and plants, and can improve the removal rate of COD, in addition, the aerobic environment is favorable for the implementation of nitration reaction, and can obviously improve the conversion rate of NH4+ -N and the purification efficiency of NH4+ -N.

As a possible implementation manner of this embodiment, the subsurface flow constructed wetland at least includes a soil layer, a zeolite layer and a gravel layer, wetland plants are planted above the soil layer, a first water heating pipeline is arranged in the soil layer, a second water heating pipeline is arranged on the zeolite layer, a third water heating pipeline is arranged on the gravel layer, and the first water heating pipeline, the second water heating pipeline and the third water heating pipeline are connected end to end.

As a possible implementation manner of this embodiment, the surface flow constructed wetland includes a soil layer and a zeolite layer, wetland plants are planted above the soil layer, a first water heating pipeline is arranged in the soil layer, a second water heating pipeline is arranged on the zeolite layer, and the first water heating pipeline and the second water heating pipeline are connected end to end.

As a possible implementation manner of this embodiment, the water inlet of the artificial wetland reactor is located at the upper part of the artificial wetland reactor, the water outlet is located at the lower part of the artificial wetland reactor, and the water inlet and the water outlet are respectively located at two sides of the artificial wetland reactor.

As a possible implementation manner of this embodiment, when the applicant performs a test, the water inlet of the artificial wetland reactor is disposed above the artificial wetland reactor, so that the water flow and the falling process greatly increase the contact area between the water body and the atmosphere, and the aeration is sufficient, which is beneficial to improving the dissolved oxygen concentration and the pollutant removal efficiency.

As a possible implementation manner of this embodiment, the water outlet of the previous artificial wetland reactor in the two adjacent artificial wetland reactors is communicated with the water inlet of the next artificial wetland reactor through the water outlet aeration pipe; the water flow of the artificial wetland enters from the water inlet of the first artificial wetland, flows out from the water outlet, and the effluent enters the next artificial wetland after being subjected to sufficient water drop aeration through the water outlet aeration pipe until reaching the last artificial wetland. The structure makes full use of natural water head, reduces the pumping link, can make full drop aeration, and is beneficial to improving the concentration of dissolved oxygen and the removal efficiency of pollutants.

As a possible implementation manner of this embodiment, as shown in fig. 3, the front end 1/3 part of the water outlet aeration pipe is a non-porous pipe, the rear part 2/3 part of the water outlet aeration pipe is a strainer pipe with an opening on the pipe wall, and water drops from the strainer pipe section to the next artificial wetland; the non-porous pipe section part is connected with the water outlet of the previous artificial wetland, and the water filter pipe with the hole on the pipe wall is connected with the water inlet of the next artificial wetland after being connected with the non-porous pipe section, so that the design and the falling process greatly increase the contact area of the water body and the atmosphere, the aeration is sufficient, and the improvement of the concentration of dissolved oxygen and the removal efficiency of pollutants is facilitated.

As a possible implementation manner of this embodiment, the water heating pipes of the artificial wetland reactor are made of a heat conducting material, and the interval between the water pipes of the water heating pipes on the upper layer is smaller than that of the water heating pipes on the lower layer. The hot-water heating pipeline has the material of good heat conductivity to make, and it is denser (vertical interval is less) in upper plant roots district when laying, and the lower floor is comparatively sparse (vertical interval is great), so both can guarantee the temperature in plant roots district, avoids the plant to freeze and dies, and the wetland top layer is frozen when also can prevent that the air temperature is lower.

As a possible implementation manner of this embodiment, the wetland plant is a calamus plant with a relatively thick root system, and the pores in the artificial wetland can be increased, so that the water holding volume of the artificial wetland is increased, phosphorus in the water body can react for a relatively long time, and the removal rate of the artificial wetland system to TP is increased.

The composite artificial wetland system can be reconstructed by utilizing waste buildings and overpasses, and can also be made into a spiral stepped wetland system by utilizing hills and soil packets according to local conditions, as shown in figure 4.

In order to verify the artificial wetland of the invention, experiments were carried out in the inventor's laboratory.

The experiment is divided into a spiral composite artificial wetland (hereinafter referred to as group B, shown in figure 2) and a common composite artificial wetland (hereinafter referred to as group A, shown in figure 5), which are composed of five wetland reactors. And the group A is a control group of wetland reactors, and a peristaltic pump is used for pumping water between the wetland reactors so as to realize the movement of sewage between the wetlands. The group B is a spiral stair shape formed by connecting underflow, surface flow and underflow in series and is used for simulating a spiral composite artificial wetland as shown in figure 2. The A1, A3, A5, B1, B3 and B5 wetlands are subsurface flow constructed wetlands, the length multiplied by the width multiplied by the height of each wetland reactor is 0.4m multiplied by 0.25m, and the matrix filling height is 0.21 m. The A2, A4, B2 and B4 wetlands are surface flow constructed wetlands, the length multiplied by the width multiplied by the height of the wetland reactor is 0.4m multiplied by 0.25m multiplied by 0.2m, the filling height of the substrate is 0.08m, and the water level is kept at about 0.07 m. The experiment uses an NKP peristaltic pump to pump water, wild grass-leaved sweetflag is planted in the wetland, and the planting density is 30 plants/m 2 in order to ensure that the plants have sufficient growing space. The experimental results are as follows:

the wetland substrate has the advantages of good purification effect, simple acquisition way, low price, safety and no toxicity, and the specific surface area, the porosity and the like of the substrate are also considered, so that the wetland substrate has strong purification capability on sewage, can effectively control the cost investment, and is favorable for embodying the characteristic of saving the cost of the artificial wetland technology.

In the experiment, gravel, zeolite and sandy loam are selected as wetland substrates according to the characteristics of convenient material acquisition, low price and the like. The wetland matrix is filled according to the principle that the particle size decreases progressively from bottom to top after being screened, washed and dried, the subsurface flow constructed wetland comprises 3 layers, the surface flow constructed wetland comprises 2 layers, and the thickness and the particle size of each layer are shown in tables 1 and 2.

Table 1: design of substrate layer of subsurface flow constructed wetland

Table 2: substrate layer design of surface flow constructed wetland

The two groups of wetland experiments adopt an intermittent water feeding mode, and the hydraulic retention time is 1-2 days. Because the purification capacity of the constructed wetland is reduced when the temperature is too low or too high, the experiment is selected to be carried out in autumn, and the laboratory temperature is 23-26 ℃. After the wetland operation and the plant growth condition are stable, water samples are taken at every other 3 days at the water outlets of the wetland for measurement for 45 days and 15 times, wherein the main measurement items comprise COD, NH4+ -N and TP, and the measurement method is shown in Table 3.

Table 3: contaminant determination method

The wetland effluent is filtered and then detected, and main instruments used for water sample detection are a spectrophotometer for detecting NH4+ -N and TP and a COD digestion instrument.

Through experiments, the pollutant removal effect is as follows:

the COD removing effect. The result shows that the COD removal efficiency of the two groups of wetlands is relatively stable, the COD concentration of the inlet water of the two groups of artificial wetlands is 198.50mg/L, the average outlet water concentration of the group A is 53.14mg/L, the average removal rate is 73.23%, and the highest removal rate is only 74.50%; and the average effluent concentration of the group B is 39.21mg/L, the average removal rate is 80.25 percent, and the highest removal rate reaches 81.53 percent. It can be seen, however, that under the same test conditions, the group B removal rate was higher.

② ammonia nitrogen removal effect. The concentration of NH4+ -N of the inlet water of the artificial wetland is 28.50mg/L, the average outlet water concentration of the group A is 10.80mg/L, the removal rate is 62.11 percent, and the highest removal rate is 64.35 percent. Because the drop aeration can enrich oxygen in the sewage, and the surface flow artificial wetland between the two subsurface flow artificial wetlands provides buffer for the anoxic environment of the subsurface flow artificial wetland, the nitrification and denitrification reaction can be carried out more smoothly, the average effluent concentration of the group B is as low as 7.81mg/L, the removal rate reaches 72.60%, and the highest removal rate is 75.40%. In terms of average removal effect, the stepped composite artificial wetland is superior to a common composite artificial wetland, and the removal rate is 10 percent higher.

③ the average effluent concentration of the group A is 0.54mg/L, the removal rate is 77.56 percent, and the highest removal rate is 79.58 percent. The average effluent concentration of the group B is 0.44mg/L, the removal rate is 81.50 percent, and the highest removal rate is 83.16 percent. Because the substrate adsorption and the plant absorption are main removing modes, the TP removing effect of the two groups of wetlands is not greatly different, but the growth of plants is facilitated due to the increase of the oxygen content, and the ladder-shaped structure is superior to the common structure.

In order to more intuitively show the advantage of saving the land area of the novel spiral composite artificial wetland, the experimental wetland reactor is taken as an example for estimation, and the occupied areas of the artificial wetlands with three different structures are shown and compared. The artificial wetland comprises a common composite artificial wetland, a ladder-type artificial wetland constructed by attaching to a side slope and a novel spiral composite artificial wetland, and is shown in figure 6, wherein the common artificial wetland, the side slope and the novel spiral composite artificial wetland are respectively shown in the figure.

In order to more intuitively show the advantage of land area saving of the novel spiral composite artificial wetland, the experimental wetland reactor is taken as an example for estimation (the size of the subsurface flow artificial wetland reactor is 0.4m multiplied by 0.25m, and the size of the surface flow artificial wetland reactor is 0.4m multiplied by 0.25m multiplied by 0.20m), and the occupied areas of the artificial wetlands with three different structures are shown and compared. The artificial wetland comprises a common composite artificial wetland, a step-type artificial wetland constructed by attaching to a side slope and a novel spiral composite artificial wetland. When the number of the wetlands is less than 5, the floor areas of the three wetlands are not greatly different and are increased along with the increase of the number of the wetlands; when the number of the wetlands is 5-7, the occupied area of the spiral artificial wetland is slightly higher than that of the other two types. However, when the number of the wetlands reaches 10, the floor area of the spiral type artificial wetland is only 0.91m2, which is smaller than that of the common composite artificial wetland of 1m2 and the ladder type artificial wetland of 1.15m2, and the floor area required when the number of the wetlands exceeds 10 is constant to 0.91m2, but the floor areas of the other two wetlands are in a linear growth mode. It can be seen that the spiral stepped structure is superior to the other two in terms of floor space, and the advantage is more obvious in the case of the larger number of wetlands.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.