CN105217793A - The artificial wet land system of the annual stabilizing treatment sanitary sewage of built-up type and operation method - Google Patents

Abstract

The invention discloses a combined artificial wetland system and an operating method for stably treating domestic sewage throughout the year. It consists of an emergent plant wetland, a submerged plant wetland, and a sewage pump. The emergent plant wetland and the submerged plant wetland are combined. A valve is set at the combination, and the sewage pump is set in the submerged plant wetland, and the sewage pump guides the water in the submerged plant wetland into the emergent plant wetland in summer; Operation mode. The present invention uses temperature-loving emergent water plants such as reeds and cattails and cold-loving submerged plants such as weed and elodea to combine the two seasonal plants to achieve complementarity in the system and effectively overcome the low carbon-nitrogen ratio of summer sewage and the The defects of traditional surface flow constructed wetlands are greatly affected by seasons.

Description

Combined artificial wetland system and operation method for stably treating domestic sewage throughout the year

technical field

The invention belongs to the technical field of environmental engineering sewage treatment, and in particular relates to a combined artificial wetland system and an operating method for stably treating domestic sewage throughout the year.

Background technique

As a sewage ecological treatment process, constructed wetland has been widely used in domestic sewage treatment due to its advantages of low investment, low energy consumption, good effect, and simple maintenance and management. Constructed wetlands are generally divided into surface flow constructed wetlands and subsurface flow constructed wetlands. Compared with subsurface flow constructed wetlands, surface flow constructed wetlands have the advantages of low investment and simple process.

There are still many problems in the existing surface flow constructed wetlands. The main points are as follows: the plant species in the system are single, mostly emergent plants such as reeds and cattails; in northern China, most emergent plants will wither in winter, and even It will rot and release pollutants, which will greatly reduce the purification effect of constructed wetlands in winter; in summer, the carbon-nitrogen ratio in domestic sewage is low, and the carbon source content is relatively low. The denitrification effect in the wetland system has not been fully exerted, resulting in a decline in wetland utilization efficiency.

Contents of the invention

The purpose of the present invention is to provide a combined constructed wetland system and operation method for stably treating domestic sewage throughout the year, aiming at the problems of reduced winter operation effect of the current surface flow constructed wetland technology and low carbon-nitrogen ratio of wetland inflow in summer, to provide a It is a combined surface flow artificial wetland based on the optimal configuration of seasonal plants with low investment, good effect treatment, relatively simple maintenance.

In order to achieve the above object, the present invention adopts the following technical solutions:

A combined artificial wetland system for stably treating domestic sewage throughout the year is composed of an emergent plant wetland, a submerged plant wetland, and a water delivery device. The emergent plant wetland is connected to the submerged plant wetland through a water guide device. A valve is arranged on the water guide device, the water delivery device is arranged in the submerged plant wetland, and the water delivery device guides the water in the submerged plant wetland into the emergent plant wetland.

The sewage pump guides water into the emergent plant wetland through a return pipe, and a flow meter is installed on the return pipe.

Said combination is series type, circulation type and parallel type.

The system adopts the operation mode of continuous water intake and pushing out water, as follows: when both the submerged plants and the emergent plants are in the growth state, the valve is opened, the water delivery device is closed, and the sewage flows through the two wetlands. Discharge after purification; when the emergent plants are in a growing state and the submerged plants are in a decaying state, the valve is closed, the water delivery device is opened, the water in the submerged plant wetland is introduced into the emergent plant wetland, and the sewage is discharged from the emergent plant The plant wetland is discharged after treatment; when the submerged plants are in the growth state and the emergent plants are in the rotten state, the valve is opened, the water delivery device is closed, the sewage flows through the emergent plant wetland to filter and intercept, and the submerged plant wetland is purified and treated. discharge.

A tandem seasonal plant combination wetland, which is composed of emergent plant wetlands and submerged plants in series. Water inlets and water outlets are set in the emergent plant wetlands and the submerged plant wetlands, and the water outlets are connected to A water collection channel, the water outlet is installed on one side of the water collection channel, and the water outlet on the side of the emergent plant wetland water collection channel is connected to the submerged plant wetland through a pipeline with a valve, and a sewage pump is installed in the submerged plant wetland , the sewage pump is connected to a return pipe, and the return pipe leads to the water inlet of the emergent plant wetland, and a valve and a flow meter are installed on the return pipe.

The operating mode of the tandem seasonal plant combination wetland is as follows: it operates in the mode of continuous water inflow and push outflow. From April to June, the valve is opened, the sewage pump is closed, and the water flow sequentially flows into the water inlet of the emergent plant wetland, the emergent plant Wetland water outlet, emergent plant wetland catchment canal, submerged plant wetland water inlet, submerged plant wetland water outlet, and finally water outlet through the submerged plant wetland catchment canal, and emergent plants and submerged plants play a purifying role at the same time; 7- In August, the valve is closed, the sewage pump is turned on, and the water flow sequentially flows into the water inlet of the emergent plant wetland, the water outlet of the emergent plant wetland, and finally flows directly through the water collection channel of the emergent plant wetland, and the water stored in the emergent plant wetland returns to the emergent plant wetland ; From September to April of the following year, the water intake mode is restored, and the emergent plant wetland mainly uses the substrate to filter and intercept, and the submerged plant plays the main role of purification.

A circulating seasonal plant combination artificial wetland, the main part of the wetland is composed of the emergent plant wetland in the outer ditch, the submerged plant wetland in the inner ditch and the central island, and the ditches are separated by retaining walls, the retaining walls There are transmission holes; the inner ditch is provided with two gates, and the water inlet of the inner ditch is provided with a sewage pump connected to a return pipe, and a valve and a flow meter are installed on the return pipe; the bottom of the central island is connected to a drain pipe, and the The drain pipe is equipped with a valve and a flow meter.

The operating mode of the circulation-type seasonal plant combination artificial wetland is as follows: the wetland adopts the operation mode of continuous water inflow and pushing water out. From April to June, the gate of the inner ditch is opened, the sewage pump is closed, and the water flows into the outer ditch from the transmission hole. Enter the inner ditch through the transfer hole, and then enter the central island through the transfer hole, and the purified water is discharged through the bottom drain pipe; from July to August, the two gates are closed, the sewage pump is turned on, and the water stored in the inner ditch is returned to the outer ditch through the control valve. After the water from the outer ditch passes through the transmission hole, it will directly enter the central island through the transmission hole and be discharged through the drainage pipe; from September to March of the following year, the wetland will return to the operation mode from April to June.

A parallel seasonal plant combination wetland, which is composed of emergent plant wetland and submerged plant wetland in parallel. The water plant wetland outlet branch pipe and the submerged plant wetland water outlet branch pipe, the water inlet branch pipe of the emergent plant wetland and the submerged plant wetland water inlet branch pipe are equipped with flow control valves, and the submerged plant wetland is equipped with A sewage pump, the sewage pump is connected to a return pipe, the return pipe is equipped with a valve and a flow meter, and the return pipe passes through the water retaining wall to connect to the emergent plant wetland.

In the parallel seasonal plant combination wetland, from April to June, the emergent plant wetland and the submerged plant wetland operate in parallel, the water inflow is equal, and the sewage pump is closed; from July to August, the flow control of the branch pipe entering the submerged plant wetland is closed. valve, close the outlet branch pipe of the submerged plant wetland, turn on the sewage pump, and pass the water stored in the submerged plant wetland into the emergent plant wetland; from September to October, close the sewage pump, and compare the water inflow of the submerged plant wetland with that of the emergent plant wetland The water inflow is controlled at 1:3, and emergent plants play the main role of purification; from November to March of the following year, adjust the flow control valve to control the water inflow of submerged plant wetlands and the water inflow of emergent plants at 3:1. Water plant wetlands are the main body of purification, and emergent plant wetlands rely on root microorganisms and matrix absorption to purify water quality.

Technical thought of the present invention is as follows:

The present invention adopts a combined surface flow artificial wetland system, and there are three types of construction methods, which are divided into series seasonal plant combination wetland (Figure 1), circulation type seasonal plant combination wetland (Figure 2), and parallel seasonal plant combination wetland (image 3). The hydraulic gradient of the constructed wetland is 0.1%-0.5%, and the water intake methods of the three combined wetlands are all continuous water intake. In northern China, emergent plants such as reeds bloom and bear fruit in spring, stop growing in autumn, and wither in winter, while cold-loving submerged plants germinate in autumn, winter is the dominant growth period, spring is the rapid growth period, and summer rots. The two kinds of plants are quite different in the developmental process, and the combination of the two plants can complement each other in time and space. The combined wetland planting method uses cold-loving submerged plants and warm-loving emergent plants to plant together. There are plants in the growth period throughout the year, which improves the stability of sewage treatment in the constructed wetland throughout the year. In addition to improving the treatment capacity through plant matching, the combined wetland adopts a unique operation mode for the low carbon-nitrogen ratio of sewage in summer. In summer, submerged plants rot and release carbon sources, stop water entering the submerged plant wetland, and store water in the Proportional access to emergent plant wetlands increases the carbon-to-nitrogen ratio of sewage and improves the denitrification capacity of wetlands in summer. Emergent plants with the strongest purification capacity play a purifying role alone. In autumn, submerged plants germinate and restore the previous operation mode. Two Wetlands work together to purify. Parallel wetlands realize backflow in summer to increase carbon sources, and at the same time, according to the differences in the treatment capacity of plants in parallel treatment units in other seasons, different water inflow ratios are designed. The water inflow ratio of submerged plant treatment units and emergent plant treatment units is 1:3 in autumn , 3:1 in winter and 1:1 in spring. The three combination wetlands all solve the problems of low wetland treatment efficiency in winter and insufficient carbon source of sewage in summer, so that the surface flow constructed wetland has the ability to treat sewage stably throughout the year.

Beneficial effects of the present invention:

(1) The present invention uses temperature-loving emergent water plants such as reeds and cattails, and cold-loving submerged plants such as Smilax and Elodea to combine the two seasonal plants to achieve complementarity in the system and effectively overcome the traditional artificial surface flow. Wetlands are greatly affected by seasons.

(2) The present invention has eliminated the influence that the submerged plants rot in July-August, passes the water after the rot occurs into the emergent plant artificial wetland in proportion, turns waste into treasure, and increases the rate of entering the emergent plant wetland The carbon source effectively overcomes the problem that the denitrification effect is affected by the lack of carbon source in the month when the wetland is in the lowest carbon-to-nitrogen ratio.

(3) The present invention has rich plant species, high biological diversity inside the wetland, enhanced ability of the wetland to bear different loads, and high stability of sewage treatment.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 of the present invention,

1-gravel layer, 2-river sand layer, 3-emergent plant reed, 4-submerged plant weed, 5-emergent plant wetland water inlet, 7-emergent plant wetland water inlet pipe, 10-submerged plant wetland Water inlet pipe, 11-submerged plant wetland water inlet, 12-sewage pump, 13-return pipe, 14-flow meter, 6-a-emergent plant wetland water outlet, 6-b-emergent plant wetland catchment canal outlet , 6-c-water outlet of submerged plant wetland, 8-a-water inlet valve of emergent plant wetland, 8-b-water inlet valve of submerged plant wetland, 8-c-return pipe valve, 9-a-emergent water Plant wetland catchment channel, 9-b-submerged plant wetland catchment channel;

Fig. 2 is the structural representation of embodiment 2 of the present invention,

1-outer ditch (emergent plant wetland), 2-inner ditch (submerged plant wetland), 3-central island, 4-retaining wall, 6-gate, 7-return pipe, 8-sewage pump, 11-drainage Pipe, 5-a-outer groove transfer hole, 5-a-inner groove transfer hole, 5-c-central island transfer hole, 9-a-return pipe valve, 9-b-drain pipe valve, 10-a-backflow Pipe Flow Meter, 10-b-Drain Pipe Flow Meter;

Fig. 3 is a schematic structural view of Embodiment 3 of the present invention,

1-water inlet main pipe, 4-sewage pump, 5-return water pipe, 6-water outlet branch pipe, 7-water outlet main pipe, 8-valve, 9-flow meter, 10 water retaining wall, 2-a-submerged plant wetland water inlet Branch pipe, 2-b-water inlet branch pipe for emergent plant wetland, 3-a-flow control valve for water inlet branch pipe for submerged plant wetland, 3-b-flow control valve for water inlet branch pipe for emergent plant wetland, 6-a-submerged water Plant wetland water outlet branch pipe, 6-b-emergent plant wetland water outlet branch pipe.

detailed description

Example 1

As shown in Figure 1, the combined wetland is a series seasonal plant combination wetland, which is composed of two artificial wetlands in series. The emergent plant wetland A is planted with emergent plants reed 3, and the submerged plant wetland B is planted with cold-loving submerged plants. Grass 4. There are two layers of matrix in the wetland, the bottom layer is the anti-seepage layer, the top of the anti-seepage layer is the gravel layer 1, and the river sand layer 2 is above the gravel layer, and the hydraulic gradient is 0.5%. Water inlet 5 and emergent plant wetland water outlet 6-a are set in emergent plant wetland A, water inlet 5 is connected to water inlet pipe 7, and emergent plant wetland water inlet pipe valve 8-a is installed on the water inlet pipe, and emergent plant wetland outlet Water outlet 6-a is connected to emergent plant wetland catchment channel 9-a, and there is outlet 6-b of emergent plant wetland catchment channel on one side of the catchment channel, and emergent plant wetland catchment channel outlet 6-b is connected to submerged plant water inlet pipe 10. The water inlet pipe 10 is equipped with a submerged plant wetland water inlet valve 8-b; the submerged plant wetland B is provided with a water inlet 11, a submerged plant wetland water outlet 6-c, and the submerged plant wetland water outlet 6-c is connected to the submerged plant wetland. The water plant wetland catchment channel 9-b, the submerged plant wetland B is equipped with a sewage pump 12, the sewage pump 12 is connected to the return pipe 13, one end of the return pipe 13 is connected to the sewage pump 12, and the other end is connected to the water inlet pipe 7 of the emergent plant wetland, and the return pipe 13 Install return pipe valve 8-c and flowmeter 14. The anti-seepage layer construction material is reinforced concrete, the water collection channel construction material is concrete, and the water delivery pipes are cast iron pipes.

The specific operation process of the above-mentioned combined surface flow constructed wetland is as follows:

It operates in the mode of continuous water intake and push flow out. From April to June, the water inlet valve 8-a of the emergent plant wetland and the water inlet valve 8-b of the submerged plant wetland are opened, the return pipe valve 8-c is closed, and the sewage pump 12 Closed, the water flows into the water inlet pipe 7, the water inlet 5, the emergent plant wetland water outlet 6-a, the emergent plant wetland water collection channel 9-a, the emergent plant wetland water collection channel outlet 6-b, and the submerged plant water inlet pipe in sequence 10. The water inlet 11 of the submerged plant wetland is finally discharged through the submerged plant wetland catchment channel 9-b. At this stage, the emergent plants and the submerged plants play a purifying role at the same time; from July to August, the emergent plants have a strong purification ability at this time , the microbial activity in the wetland is high, and can play a purifying role alone. The submerged plants are already in a state of decay and release carbon sources. The water inlet valve 8-b is closed, the sewage pump 12 is turned on, and the water flow sequentially flows into the water inlet pipe 7, the water inlet 5, the emergent plant wetland water outlet 6-a, and finally flows out directly through the emergent plant wetland catchment channel 9-a, and the water is submerged The plant wetland stores water by controlling the flow meter 14 to adjust the water volume and return the water to the emergent plant wetland A in proportion to increase the carbon-nitrogen ratio; from September to April of the following year, the water intake mode is restored. From September onwards, the reeds gradually wither. In winter, the emergent plant wetland A mainly uses the matrix to filter and intercept, and the submerged plants mainly play the role of purification.

Example 2

As shown in Figure 2, the combined wetland is a circular seasonal plant combined artificial wetland. The main body of the wetland is composed of an outer ditch 1, an inner ditch 2 and a central island 3. The outer ditch 1 is planted with emergent plants, and the inner ditch 2 is planted with submerged plants. Each ditch is separated by a retaining wall 4 . There are transmission holes on the water retaining wall 4; two gates 6 are set in the inner ditch 2, and a sewage pump 8 connected to the return pipe 7 is installed at the water inlet of the inner ditch 2, and the return pipe valve 9-a and the flow rate of the return pipe are installed on the return pipe 7 Meter 10-a; the bottom of the central island 3 is connected to a drainpipe 11, and the drainpipe 11 is equipped with a drainpipe valve 9-b and a drainpipe flowmeter 10-b. The structure of the wetland matrix and the types of water pipes are the same as in Example 1, and the retaining wall is constructed with reinforced concrete.

The specific operation process is:

The wetland adopts the operation mode of continuous water inflow and push outflow. From April to June, the plants in the two ditches are in a growing state, and the purification effect occurs together. During this period, the gate 6 of the inner ditch is opened, the sewage pump 8 is closed, and the water flows from the transmission hole 5-a of the outer ditch into the outer ditch. The transmission hole 5-b of the inner ditch enters the inner ditch, and then enters the central island through the transmission hole 5-c of the central island, and the purified water is discharged through the bottom drain pipe 11; from July to August, the emergent plants in the outer ditch 1 grow luxuriantly and develop independently. Purification, the submerged plants in the inner ditch 2 rot and release carbon sources. At this stage, the two gates 6 are closed, the sewage pump 8 is turned on, and the water stored in the inner ditch 2 is returned to the outer ditch in proportion by controlling the return pipe valve 9-a 1. Improve the carbon source of sewage in outer ditch 1. After the water from outer ditch 1 passes through the transmission hole 5-b of the inner ditch, it enters the central island directly from the transmission hole 5-c of the central island and is discharged through the drainage pipe 11; September - next year 3 In April, the wetland returns to the operation mode from April to June. During this time period, the cold-loving submerged plants begin to resume their purification function after germination. During the overwintering period, the submerged plants play the main role of purification, and the wetland of emergent plants mainly plays the role of sedimentation and interception. . This wetland can withstand high pollution load, improve area utilization rate, enhance denitrification capacity in summer, and achieve stable sewage treatment capacity throughout the year.

Example 3

As shown in Figure 3, the artificial wetland is composed of emergent plant wetland B and submerged plant wetland A, and the main water inlet pipe 1 is divided into emergent plant wetland water inlet branch 2-b and submerged plant wetland water inlet branch 2-a , the water outlet main pipe 7 is divided into the emergent plant wetland water outlet branch pipe 6-b and the submerged plant wetland water outlet branch pipe 6-a, the emergent plant wetland water inlet branch pipe 2-b and the submerged plant wetland water inlet branch pipe 2-a Flow control valves are respectively installed, and a sewage pump 4 is installed in the submerged plant wetland. The sewage pump 4 is connected to the return pipe 5, and the return pipe 5 is equipped with a valve 8 and a flow meter 9. The return pipe 5 passes through the water retaining wall 10 to connect to the water plant wetlands. The structure of the wetland substrate and the type of water delivery pipes are the same as in Example 1, and the structure of the retaining wall is the same as in Example 2.

The specific operation process is:

From April to June, both submerged plants and emergent plants have a good purification effect. The two artificial wetlands are operated in parallel, the water intake is equal, and the sewage pump 4 is closed; from July to August, the submerged plants are rotten, and the submerged plants are closed. The flow control valve 3-a of the wetland water inlet branch pipe closes the water outlet branch pipe 6-1 of the submerged plant wetland, turns on the sewage pump 4, and passes the water stored in the wetland into the emergent plant wetland B in proportion to increase the carbon source by adjusting the valve 8, Increase the carbon-to-nitrogen ratio of sewage in summer; from September to October, turn off the sewage pump 4, adjust the flow control valve 3-a of the water inlet branch pipe of the submerged plant wetland and the flow control valve 3-b of the water inlet branch pipe of the emergent plant wetland, and put the submerged plant wetland The water inflow and emergent plants are controlled at 1:3. At this stage, submerged plants germinate and gradually play a purifying role, and emergent plants play the main purifying role; from November to March of the next year, adjust the flow control valve to The water intake of aquatic plants and emergent plants is controlled at about 3:1. At this stage, submerged plants are the main body of purification, and emergent plant wetland B relies on root microorganisms and matrix absorption to purify water quality. The artificial wetlands operate in parallel, adjusting the water intake according to the different characteristics of plants and sewage in different seasons, giving full play to the advantages of seasonal plants, and realizing the ability to purify water quality stably throughout the year.

After testing, the combined wetland has a stable removal rate of COD of more than 75% throughout the year, ammonia nitrogen removal rate of more than 80%, TN removal rate of more than 80%, and TP removal rate of more than 85%. Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (10)

1. A combined artificial wetland system for stably treating domestic sewage throughout the year, characterized in that it is composed of emergent plant wetlands, submerged plant wetlands, and water delivery devices, and the emergent plant wetlands are connected to the submerged wetlands through water guides. The water plant wetland is connected, the water guiding device is provided with a valve, the water delivery device is arranged in the submerged plant wetland, and the water delivery device guides the water in the submerged plant wetland into the emergent plant wetland. 2. The system according to claim 1, wherein the sewage pump guides water into the emergent plant wetland through a return pipe, and a flow meter is installed on the return pipe. 3. The system according to claim 1, characterized in that: the combination is series, circulation or parallel. 4. The operation mode of the system according to any one of claims 1-3, characterized in that: the system adopts the operation mode of continuous water inflow and pushing water out, specifically as follows: both submerged plants and emergent plants are in the growth stage. state, the valve is opened, the water delivery device is closed, and the sewage is discharged after passing through the two wetlands; when the emergent plants are growing and the submerged plants are in a decaying state, the valve is closed, and the water delivery device is opened , the water in the submerged plant wetland is introduced into the emergent plant wetland, and the sewage is discharged after being treated by the emergent plant wetland; when the submerged plants are in a growing state and the emergent plants are in a rotting state, the valve is opened, and the water delivery The unit is closed and the sewage flows through two wetlands for treatment before being discharged. 5. A tandem seasonal plant combination wetland, characterized in that: both the emergent plant wetland and the submerged plant wetland are provided with water inlets and water outlets, and the water outlets are connected to a water collection channel, and the emergent plant wetlands A water outlet is installed on one side of the water plant wetland water collection channel, and the water outlet on the side of the emergent water plant wetland water collection channel is connected to the submerged plant wetland through a pipeline with a valve. The submerged plant wetland is equipped with a sewage pump, and the sewage The pump is connected with a return pipe, and the return pipe leads to the water inlet of the emergent plant wetland, and a valve and a flow meter are installed on the return pipe. 6. The operation mode of the wetland according to claim 5, characterized in that: from April to June, the valve is opened, the sewage pump is closed, and the water flow sequentially flows into the water inlet of the emergent wetland, the water outlet of the emergent wetland, and the water of the emergent plant. Wetland catchment canal, submerged plant wetland water inlet, submerged plant wetland water outlet, and finally through the submerged plant wetland catchment canal, where emergent plants and submerged plants play a purifying role at the same time; from July to August, the valve is closed and the sewage When the pump is turned on, the water flows into the water inlet of the emergent plant wetland, the water outlet of the emergent plant wetland in sequence, and finally flows out directly through the water collection channel of the emergent plant wetland, and the water stored in the submerged plant wetland returns to the emergent plant wetland; from September to April of the following year In March, the water intake mode was restored, and the emergent plant wetland mainly used the matrix to filter and intercept, and the submerged plants played the main role of purification. 7. A circulating seasonal plant combination artificial wetland is characterized in that it is composed of emergent plant wetlands in the outer ditch, submerged plant wetlands in the inner ditch and a central island, and each ditch is separated by a retaining wall. There are transmission holes on the water retaining wall, two gates are set in the inner ditch, and a sewage pump connected to a return pipe is installed at the water inlet of the inner ditch, and a valve and a flow meter are installed on the return pipe; the bottom of the central island is connected to a drainage pipe. The drain pipe is equipped with a valve and a flow meter. 8. The operation mode of the wetland according to claim 7, characterized in that: from April to June, the gate of the inner ditch is opened, the sewage pump is closed, the water flow enters the outer ditch from the transmission hole, enters the inner ditch through the transmission hole, and then passes through the transmission hole. The hole enters the central island, and the purified water is discharged through the bottom drainage pipe; from July to August, the two gates are closed, the sewage pump is turned on, and the water stored in the inner ditch is returned to the outer ditch through the control valve. The transmission hole enters the central island and is discharged through the drainage pipe; from September to March of the following year, the wetland returns to the operation mode from April to June. 9. A parallel seasonal plant combination wetland, characterized in that: the water inlet main pipe is divided into an emergent plant wetland water inlet branch pipe and a submerged plant wetland wetland water inlet branch pipe, and the water outlet pipe is divided into an emergent plant wetland water outlet branch pipe and a submerged plant wetland water inlet branch pipe. A water plant wetland outlet branch pipe, a flow control valve is installed in the emergent plant wetland water inlet branch pipe and the submerged plant wetland water inlet branch pipe, a sewage pump is installed in the submerged plant wetland, and the sewage pump Connect the return pipe, the return pipe is equipped with a valve and a flow meter, and the return pipe passes through the water retaining wall to connect to the emergent plant wetland. 10. The operation mode of the wetland according to claim 9, characterized in that: from April to June, the emergent plant wetland and the submerged plant wetland operate in parallel, the water inflow is equal, and the sewage pump is closed; The flow control valve of the submerged plant wetland branch pipe closes the submerged plant wetland water outlet branch pipe, turns on the sewage pump, and passes the water stored in the submerged plant wetland into the emergent plant wetland; from September to October, closes the sewage pump and drains the submerged plant The water intake of the wetland and the water intake of the emergent plant wetland are controlled at 1:3, and the emergent plants play the main role of purification; from November to March of the following year, adjust the flow control valve to reduce the water intake of the wetland of submerged plants to that of the wetland of emergent plants. The water volume is controlled at 3:1, the submerged plant wetland is the main purification, and the emergent plant wetland purifies water quality by root microorganisms and matrix absorption.