Anti-blocking anti-freezing bidirectional-flow vertical-flow constructed wetland tail water treatment method

Abstract

The invention relates to the technical field of sewage treatment, and discloses an anti-clogging and anti-freezing bidirectional-flow vertical-flow constructed wetland system which comprises a treatment unit formed by taking a plurality of constructed wetland pool bodies arranged in sequence as a basis, and a water inlet end and a water outlet end are respectively arranged at two ends of each constructed wetland pool body; water inlets are formed in the upper portion and the bottom of the water inlet end, a water outlet and an overflow port are formed in the upper portion and the bottom of the water outlet end respectively, a water inlet pipe and a water distribution pipe network are arranged on the upper portion and the bottom of the water inlet end, a bottom water outlet pipe is arranged at the bottom of the water outlet end, a water outlet adjusting dam is arranged on the upper portion of the water outlet end, and the overflow port is formed in the upper portion of the water outlet adjusting dam. According to the invention, a bidirectional flow operation mode of downward flow in spring and summer and upward flow in autumn and winter is adopted, so that the purpose of preventing the packing layer of the constructed wetland from freezing by utilizing the temperature in tail water is achieved on the premise of not adding an anti-freezing moisturizing layer, and meanwhile, the purpose of preventing the packing layer from being blocked by backwashing is also achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to an anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland tail water treatment method. Background Art

[0002] Artificial wetlands are a mature sewage treatment technology. They are widely used in the treatment of domestic sewage, industrial wastewater, etc. due to their low construction cost, environmental friendliness and high efficiency. However, in the actual application of artificial wetlands, their treatment effect is affected by many factors, including environmental conditions, design factors and management methods. Artificial wetlands are greatly affected by environmental temperature changes, mainly in seasonal climate changes; the matrix and plant species selected in wetland design affect the effect and life of wetlands; in addition, the management and maintenance of artificial wetlands in the later stage will also affect their treatment effect. In the northwest region, water resources are very scarce, and the reuse of domestic sewage resources is an important research topic. In addition, because the land area in the northwest region is relatively abundant and the population is relatively dispersed, artificial wetland systems are very suitable. However, the climatic conditions in the northwest region are the main problems of artificial wetlands. Most areas have temperate continental climate and alpine climate, with high temperatures in summer, cold and dry winters, and freezing periods. Therefore, their actual effects are limited to a certain extent. Therefore, a two-way flow operation mode can be adopted to enable artificial wetlands to operate stably during the winter freezing period to ensure the treatment effect. my country has conducted some research on the bidirectional flow operation mode of artificial wetlands. For example, the Chinese patent "CN110835164" discloses a bidirectional self-cleaning anti-clogging composite vertical artificial wetland. It includes a sewage pool, a wetland pool and a water delivery pump, and purifies sewage by subsurface flow and upflow at the same time, and can perform circulation purification; another example is the Chinese patent "CN105836891" discloses a bidirectional distribution flow artificial wetland and its treatment method, which consists of a wetland treatment area and a distribution flow control area. The wetland treatment area is filled with wetland matrix and planted with wetland plants. A bidirectional distribution flow pipeline is laid inside, and the wetland treatment area and the distribution flow control area are connected in sequence according to the direction of water flow. This invention realizes the backwashing of the artificial wetland in a timely manner only by adjusting the valve through the reasonable improvement of the artificial wetland water distribution system.

[0003] However, in the existing technical field, the design of bidirectional flow systems often focuses on achieving circulation purification by changing the direction of water flow. However, this method has certain structural complexity, cumbersome wetland operation and management, and inflexible treatment conditions and processes, which limits the promotion and application of artificial wetlands in the northwest region. Summary of the invention

[0004] In view of the defects of the prior art, the present invention proposes an anti-clogging and anti-freezing bidirectional flow alternating operation vertical flow artificial wetland tail water treatment method.

[0005] The overall technical scheme of the present invention is as follows: it comprises a treatment unit composed of a plurality of artificial wetland pool bodies arranged in sequence, wherein an inlet end and an outlet end are respectively arranged at both ends of each artificial wetland pool body, an inlet is arranged at the upper part and the bottom of the inlet end, an outlet and an overflow are arranged at the bottom and the upper part of the outlet end, respectively, an inlet pipe and a water distribution network are arranged at the upper part and the bottom of the inlet end, the inlet is connected to the inlet pipe, a water inlet distribution valve is arranged on the inlet pipe, the inlet pipe is connected to a distribution pipe, the distribution pipe is connected to the water distribution network, a bottom outlet pipe is arranged at the bottom of the outlet end, the bottom outlet pipe passes through the outlet, an outlet regulating dam is arranged at the upper part of the outlet end, and the overflow is arranged at the upper part of the outlet regulating dam.

[0006] Furthermore, the water distribution network is composed of a plurality of water distribution main pipes and a plurality of water distribution branch pipes. The water distribution main pipes are distributed along the direction of the water outlet. The water distribution branch pipes are respectively installed on both sides of the water distribution main pipes. The water distribution main pipes are joined to the water distribution branch pipes at a vertical angle, and each joining point is equidistant. The plurality of water distribution main pipes and the plurality of water distribution branch pipes together form a "W"-shaped pipe network, which completely covers the artificial wetland pool.

[0007] Furthermore, the water distribution pipe is provided with a plurality of water inlet distribution valves, which are used to control the water inlet speed and flow rate of tail water entering the water distribution main pipe. The water distribution volume of each water distribution main pipe is 296m per day. 3 .

[0008] Furthermore, the water distribution main pipe is a DN100 water distribution main pipe, and the water distribution branch pipe is a DN50 water distribution branch pipe.

[0009] Furthermore, plugs are installed at the ends of the water distribution main pipe and the water distribution branch pipe.

[0010] Furthermore, a ventilation hole is provided at the top of the end of the water distribution main pipe, the diameter of the ventilation hole is 15 mm, and the ventilation hole is wrapped with a nylon sand net with an aperture of 60 meshes to prevent impurities such as mud and sand from entering the water distribution main pipe.

[0011] Furthermore, a plurality of upper water distribution holes are equidistantly arranged at the bottom of the water distribution main pipe and the water distribution branch pipe of the upper water distribution network, and a plurality of bottom water distribution holes are equidistantly arranged at the top of the water distribution main pipe and the water distribution branch pipe of the bottom water distribution network.

[0012] Furthermore, the upper water distribution holes are arranged 45° downward along the horizontal plane, and the opening centers of the two upper water distribution holes are 90° apart.

[0013] Furthermore, the bottom water distribution holes are arranged upward at 45° along the horizontal plane, and the opening centers of two bottom water distribution holes are 90° apart.

[0014] Furthermore, the openings of the upper water distribution hole and the bottom water distribution hole are both wrapped with a nylon sand mesh with an aperture of 60 meshes.

[0015] Furthermore, the water outlet regulating dam includes a step-type wall and a first vertical wall panel, the step-type wall includes a transverse wall panel, a second vertical wall panel and a third vertical wall panel, the second vertical wall panel and the third vertical wall panel are respectively perpendicular to the transverse wall panel and are respectively arranged on the upper and lower sides of the transverse wall panel, the first vertical wall panel is arranged on the transverse wall panel and is located directly above the third vertical wall panel, and a plurality of holes are opened at the bottom of the first vertical wall panel.

[0016] Furthermore, an outlet channel is provided at the outlet end of the artificial wetland pool, an outlet pipe is provided on the upper part of the outlet channel, the outlet pipe has the same height as the horizontal wall panel, and a drain pipe is provided at the right bottom of the outlet channel.

[0017] Furthermore, a plurality of perforated water collecting pipes are arranged below the bottom water distribution network, and water collecting holes are arranged on the perforated water collecting pipes. Each of the perforated water collecting pipes is connected to the bottom water outlet pipe, and the bottom water outlet pipe is connected to one end of the water outlet channel, and the other end of the water outlet channel is connected to the water outlet pipe.

[0018] Furthermore, the bottom of the third vertical wall panel is connected to the bottom water outlet pipe for drainage in a wetland treatment mode where water flows from top to bottom; and a water outlet regulating weir is installed on the top of the second vertical wall panel for drainage in a wetland treatment mode where water flows from bottom to top.

[0019] Furthermore, the length of the water outlet regulating dam is half of the length of the artificial wetland pool body, and is arranged in the middle of the water outlet end of the artificial wetland pool body.

[0020] Furthermore, the water outlet regulating weir plate is a stainless steel water outlet regulating weir plate.

[0021] Furthermore, the height of the water outlet regulating weir plate is 4-5 cm.

[0022] Furthermore, the artificial wetland pool body and the outlet regulating dam are both provided with a slope toward the outlet pipe, and the slope is 0.005.

[0023] Furthermore, the substrate depth of the artificial wetland is 1.3 m.

[0024] Furthermore, the upper water inlet pipe is made of hot-dip galvanized steel pipe.

[0025] Furthermore, the specifications of the hot-dip galvanized steel pipe are designed as follows: hot-dip galvanized steel pipe DN<50mm, connected by threaded connection, hot-dip galvanized steel pipe DN>50mm, connected by grooved connectors.

[0026] Furthermore, the water inlet pipe at the bottom is made of HDPE high-density polyethylene pipe and is connected by hot-melt connection.

[0027] Furthermore, the working pressure of the pipes of the upper water inlet pipe and the bottom water inlet pipe is 0.6 MPa.

[0028] Furthermore, the water inlet distribution valve is connected to the water inlet pipe section by a flange connection.

[0029] Furthermore, the water distribution network at the bottom adopts HDPE high-density polyethylene pipes.

[0030] Furthermore, each artificial wetland pool is provided with a PLC control system and a flow meter, and the water inlet and distribution valve and the flow meter are connected to the PLC control system.

[0031] By adopting advanced PLC control system, the water flow in each artificial wetland pool can be automatically controlled according to the time and amount of water inflow. Each artificial wetland pool is equipped with water inlet distribution valve and flow meter, which can automatically adjust according to the area of ​​artificial wetland pool without manual operation, so as to achieve absolute uniformity and precise allocation of hydraulic load.

[0032] Furthermore, aquatic plants are planted on the surface of the artificial wetland pool.

[0033] Furthermore, the aquatic plants include one or more of Lythrum salicaria, Iris pumila, Onion and Cattail.

[0034] Furthermore, the aquatic plants are planted at 12 plants / m 2 The density of planting is 20-30cm.

[0035] Furthermore, the artificial wetland pool structure includes a filler layer.

[0036] Furthermore, the packing layer comprises a gravel layer 1 with a particle size of 0.5 to 4 cm, and the thickness of the packing layer is 100 to 110 cm.

[0037] Furthermore, the gravel layer 1 includes a bottom gravel cushion layer, a secondary bottom gravel layer, an intermediate gravel layer and a medium-coarse sand filter layer, wherein the gravel diameter of the bottom gravel cushion layer is 2-4cm and the thickness is 25cm, the gravel diameter of the secondary bottom gravel layer is 1-2cm and the thickness is 25cm, the gravel diameter of the intermediate gravel layer is 0.5-1cm and the thickness is 20cm, and the gravel diameter of the medium-coarse sand filter layer is 0.5-2mm and the thickness is 30cm.

[0038] Furthermore, a water distribution layer filling layer is filled on the medium-coarse sand filter layer, and the water distribution layer filling layer is formed by filling gravel with a diameter of 0.5-1 cm and a thickness of 10 cm around the pipes of the water distribution network.

[0039] Furthermore, before winter, the aquatic plants are harvested to form a plant harvesting layer, which covers the water distribution layer filling layer.

[0040] To ensure that the water temperature is not lower than 4°C, all wetland plants are harvested and covered on artificial wetlands before winter. After winter, if some wetland plants do not sprout new buds, they need to be replanted.

[0041] The entire wetland is harvested for aquatic plants before winter, and the harvested aquatic plants form a plant insulation layer about 1 to 2 cm thick on the surface of the artificial wetland. In winter, under the upflow operation mode, water flows out of the surface of the artificial wetland pool, and the temperature of the tail water can be used to keep warm and prevent freezing.

[0042] The present invention also provides a method for treating tailwater of an anti-clogging and anti-freezing two-way flow vertical flow artificial wetland system, which adopts the above-mentioned anti-clogging and anti-freezing two-way flow vertical flow artificial wetland system. The artificial wetland pool body adopts low-flow 24-hour continuous water distribution during low-temperature operation in winter, closes all upper water inlet distribution valves, opens all bottom water inlet distribution valves, and closes the gate at the outlet end of the artificial wetland pool body to realize the vertical upward flow artificial wetland operation with bottom water distribution and upper water outlet.

[0043] During the frost period, the water distribution method of the bottom water distribution pipe network is adopted. The tail water flows from the bottom to the top through the matrix layer for filtration and microbial degradation treatment. Then the treated water is stored in the space of the artificial wetland pool that is 50 cm higher (the temperature of the treated water is still 5 to 10 degrees), so as to use the temperature of the treated water to maintain the temperature of the matrix layer in the artificial wetland pool, so that the microorganisms in the matrix layer can normally play the role of treating the tail water. At the same time, the ice cover formed by the ice on the surface of the treatment pool can also play a role in heat preservation. At the same time, the water distribution method from the bottom during the frost period can not only solve the anti-freezing problem, but also play a backwashing role, which can solve the blockage problem of the matrix layer and extend the service life of the matrix layer.

[0044] When operating in winter mode, if the weir trough is frozen, manual intervention is required, such as breaking the ice, to ensure that the outlet weir is unobstructed to prevent water accumulation due to freezing.

[0045] Furthermore, when the vertical flow artificial wetland pool is operated in summer, it operates in a vertical flow downward flow artificial wetland mode with upper water distribution and bottom water outlet. All bottom water inlet and distribution valves are closed, all upper water inlet and distribution valves are opened, and the gate below the water outlet is opened to realize the vertical downward flow artificial wetland mode with upper water distribution and bottom water outlet.

[0046] Furthermore, the vertical flow artificial wetland pool adopts a dry-wet alternating mode when operating in summer, completing a water distribution cycle in two days.

[0047] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a two-way flow operation mode. By establishing a set of water inlet pipes and water distribution pipes at the bottom of the artificial wetland system with the same arrangement as the upper part, and by setting up a water distribution pipe network arranged in a "W" shape, an efficient tailwater distribution network is formed. This design not only simplifies the system structure, but also improves the stability and anti-clogging ability of the system.

[0048] 2. The present invention equips each artificial wetland pool with a solenoid valve and a flow meter to ensure uniform distribution and precise dosing of the hydraulic load, thereby achieving efficient, uniform and scientific tailwater dosing management. By adopting an advanced PLC system, efficient management and intelligent control of water flow can be achieved. Compared with traditional vertical flow artificial wetlands, water distribution is more uniform and precise, greatly saving manpower.

[0049] 3. The present invention can timely realize the backwashing of the artificial wetland only by adjusting the valve, so it can intelligently adjust the operation mode according to the climate changes in different seasons to adapt to environmental requirements.

[0050] 4. The present invention can realize the two-way operation of the wetland only by adjusting the opening and closing of the water valve. In winter, when the temperature drops, the upper water inlet and water distribution valve is closed, the lower water inlet and water distribution valve is opened, and the iron gate below the outlet is closed, so that the tail water can be operated from bottom to top. This tail water flow mode helps to maintain the temperature of the water body at about 11 degrees Celsius. Generally, wetlands usually need to be covered with soil, straw mats, and plastic cloth or film to provide additional insulation, and this method can naturally achieve insulation through the flow of tail water without the need for an additional insulation layer; when summer comes, the temperature rises, the growth conditions on the surface of the water body are improved, and the growth of plants promotes the oxygen supply capacity of the water body, thereby providing favorable conditions for the biodegradation process. At this time, the lower water inlet and water distribution valve is closed, the upper water inlet and water distribution valve is opened, and the iron gate below the outlet is opened, so that the tail water can be operated from top to bottom. This seasonal change in flow pattern, i.e., upward flow in winter and downward flow in summer, forms a natural backwashing mechanism. In winter, this backwashing helps to remove sediments and pollutants and prevent wetland clogging, while in summer, it maintains water cleanliness through filtration. Through the above process, the operation mode of the present invention can fully realize the normal and smooth operation of the artificial wetland system in the cold winter in the northwest region, and is also convenient for subsequent adjustment and maintenance.

[0051] The present invention adopts a bidirectional flow operation mode of downward flow in spring and summer and upward flow in autumn and winter. Without the need to add an antifreeze and moisturizing layer, it achieves the purpose of preventing the artificial wetland filler layer from freezing by utilizing the temperature in the tail water, and also achieves the purpose of backwashing to prevent the filler layer from being blocked. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is an overall schematic diagram of the vertical flow artificial wetland structure of the present invention; Figure 2 It is a schematic diagram of the structure of the water distribution pipe network on the upper part of the vertical flow artificial wetland of the present invention; Figure 3 It is a schematic diagram of the structure of the water outlet end of the artificial wetland of the present invention; Figure 4 It is a schematic diagram of the structure of the plant planting module of the present invention; Figure 5 is a plan view of an artificial wetland of the present invention; Figure 6 yes Figure 4 Middle AA section; Figure 7 is a plan view of the perforated water collecting pipe of the present invention; Figure 8 8(a) is a schematic diagram of the water distribution main, and 8(b) is a schematic diagram of the BB cross-sectional structure in 8(a); In the figure, 1-water inlet pipe, 2-water distribution network, 3-water outlet regulating weir plate, 4-water outlet pipe, 5-water distribution main pipe, 6-water distribution branch pipe, 7-water outlet channel, 8-vent pipe, 9-perforated water collecting pipe, 10-bottom water outlet pipe, 11-water inlet distribution valve, 12-water distribution pipe, 13-bottom gravel cushion layer, 14-second bottom gravel layer, 15-middle gravel layer, 16 medium-coarse sand filtration layer, 17-water distribution layer filling layer, 18-plant harvesting layer, 19 water outlet regulating dam, 20 first vertical wall panel, 21 horizontal wall panel, 22 second vertical wall panel, 23 third vertical wall panel. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some examples of the present invention, not all examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Example 1, see Figure 1-Figure 8The present invention provides an anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system, including a treatment unit composed of a plurality of artificial wetland pools arranged in sequence, wherein an inlet end and an outlet end are respectively arranged at both ends of each artificial wetland pool, an inlet is arranged at the upper part and the bottom of the inlet end, an outlet and an overflow are arranged at the bottom and the upper part of the outlet end, an inlet pipe 1 and a water distribution network 2 are respectively arranged at the upper part and the bottom of the inlet end, the inlet is connected to the inlet pipe 1, an inlet distribution valve 11 is arranged on the inlet pipe 1, a bottom outlet pipe 10 is arranged at the bottom of the outlet end, the bottom outlet pipe 10 passes through the outlet, an outlet regulating dam 19 is arranged at the upper part of the outlet end, and the overflow is arranged at the upper part of the outlet regulating dam 19.

[0055] The water distribution network 2 is composed of a plurality of water distribution main pipes 5 and a plurality of water distribution branch pipes 6. The water distribution main pipes 21 are distributed along the direction of the water outlet. The water distribution branch pipes 6 are respectively installed on both sides of the water distribution main pipes 5. The water distribution main pipes 21 are connected to the water distribution branch pipes 6 at a vertical angle, and each connection point is equidistant. The plurality of water distribution main pipes 5 and the plurality of water distribution branch pipes 6 together form a "W"-shaped pipe network, which completely covers the top of the artificial wetland pool.

[0056] The water inlet pipe 1 is connected to the water distribution pipe 12, and the water distribution pipe 12 is provided with a water inlet distribution valve 11, which is used to control the water inlet speed and flow rate of the tail water entering the water distribution main pipe 5. The water distribution capacity of each water distribution main pipe 5 is 296m per day. 3 .

[0057] The water distribution main pipe 5 is a DN100 water distribution main pipe, and the water distribution branch pipe 6 is a DN50 water distribution branch pipe.

[0058] Plugs are installed at the ends of the water distribution main pipe 5 and the water distribution branch pipe 6.

[0059] A vent hole is provided at the top of the end of the water distribution main pipe 5, the diameter of the vent hole is 15 mm, and the vent hole is wrapped with a nylon sand net with an aperture of 60 meshes.

[0060] When the water distribution network 2 is arranged at the top, several upper water distribution holes are arranged at equal distances on the bottom of the water distribution main pipe 5 and the water distribution branch pipe 6. When the water distribution network is arranged at the bottom, several bottom water distribution holes are arranged at equal distances on the top of the water distribution main pipe 5 and the water distribution branch pipe 6.

[0061] The upper water distribution holes are arranged 45 degrees downward along the horizontal plane, and the opening centers of the two upper water distribution holes are 90 degrees apart.

[0062] The bottom water distribution holes are arranged upward at 45° along the horizontal plane, and the opening centers of the two bottom water distribution holes are 90° apart.

[0063] The openings of the upper water distribution holes and the bottom water distribution holes are wrapped with nylon sand mesh with an aperture of 60 meshes.

[0064] The water outlet regulating dam 19 includes a stepped wall and a first vertical wall panel 20. The stepped wall includes a horizontal wall panel 21, a second vertical wall panel 22 and a third vertical wall panel 23. The second vertical wall panel 22 and the third vertical wall panel 23 are respectively perpendicular to the horizontal wall panel 21 and are respectively arranged on the upper and lower sides of the horizontal wall panel 21. The first vertical wall panel 20 is arranged on the horizontal wall panel 21 and is located directly above the third vertical wall panel 23. A plurality of holes are opened at the bottom of the first vertical wall panel 20.

[0065] An outlet channel 7 is provided at the outlet end of the artificial wetland pool, an outlet pipe 4 is provided on the upper part of the outlet channel 7, the outlet pipe 4 is at the same height as the horizontal wall panel 21, and a drain pipe is provided at the right bottom of the outlet channel 7.

[0066] A plurality of perforated water collecting pipes 9 are arranged at the bottom of the artificial wetland pool, and water collecting holes are arranged on the perforated water collecting pipes 9. Each perforated water collecting pipe 9 is connected to a bottom water outlet pipe 10, and the bottom water outlet pipe 10 is connected to one end of the water outlet channel 7, and the other end of the water outlet channel 7 is connected to the water outlet pipe 4.

[0067] The bottom of the third vertical wall panel 23 is connected to the bottom water outlet pipe 10, which is used for drainage in the wetland treatment mode where water flows from top to bottom; the top of the second vertical wall panel 22 is installed with a water outlet regulating weir plate 3, which is used for drainage in the wetland treatment mode where water flows from bottom to top.

[0068] The length of the outlet regulating dam 19 is half of the length of the artificial wetland pool body, and is arranged in the middle of the outlet end of the artificial wetland pool body. The outlet regulating weir plate 3 is a stainless steel outlet regulating weir plate, and the height of the outlet regulating weir plate 3 is 4-5 cm.

[0069] The artificial wetland pool and the outlet regulating dam are both sloped towards the outlet pipe, with a slope of 0.005.

[0070] The substrate depth of the artificial wetland is 1.3m.

[0071] The upper water inlet pipe 1 adopts a hot-dip galvanized steel pipe, and the specifications of the hot-dip galvanized steel pipe are as follows: hot-dip galvanized steel pipe DN <50mm, threaded connection, hot-dip galvanized steel pipe DN>50mm, grooved connector connection.

[0072] The bottom water inlet pipe 1 is made of HDPE high-density polyethylene pipe and is connected by hot-melt connection.

[0073] The pipe working pressure of the upper water inlet pipe 1 and the bottom water inlet pipe 1 is 0.6MPa.

[0074] The pipe section where the water inlet distribution valve 11 is connected to the water inlet pipe 1 is connected by a flange.

[0075] The bottom water distribution pipe network 2 adopts HDPE high-density polyethylene pipe.

[0076] Each artificial wetland pool is equipped with a PLC control system and a flow meter, and the water inlet distribution valve 11 and the flow meter are connected to the PLC control system. By adopting an advanced PLC control system, the water flow in each artificial wetland pool can be automatically controlled according to the time and amount of water inlet. Each artificial wetland pool is equipped with a water inlet distribution valve and a flow meter. These devices can be automatically adjusted according to the area of ​​the artificial wetland pool without manual operation, so as to achieve absolutely uniform and accurate allocation of hydraulic load.

[0077] Aquatic plants are planted on the surface of the artificial wetland pool.

[0078] The aquatic plants include one or more of Lythrum salicaria, Iris calamus, Onion and Cattail.

[0079] Aquatic plants: 12 plants / m 2 The density of planting is 20-30cm.

[0080] The artificial wetland pool structure includes a filler layer.

[0081] The packing layer comprises a gravel layer with a particle size of 0.5 to 4 cm, and the thickness of the packing layer is 100 to 110 cm.

[0082] The gravel layer 1 includes a bottom gravel cushion layer 13, a secondary gravel layer 14, an intermediate gravel layer 15 and a medium-coarse sand filter layer 16 from bottom to top, wherein the gravel of the bottom gravel cushion layer 13 has a diameter of 2-4 cm and a thickness of 25 cm, the gravel of the secondary gravel layer 14 has a diameter of 1-2 cm and a thickness of 25 cm, the gravel of the intermediate gravel layer 15 has a diameter of 0.5-1 cm and a thickness of 20 cm, and the gravel of the medium-coarse sand filter layer 16 has a diameter of 0.5-2 mm and a thickness of 30 cm; and then fill the water distribution layer filling layer 17, and the pipes of the water distribution network 2 are filled with gravels with a diameter of 0.5-1 cm and a thickness of 10 cm. Before winter, the surface aquatic plants of the artificial wetland are harvested to form a plant harvesting layer 18, which covers the water distribution layer filling layer 17. Example 2

[0083] The present invention provides a method for the normal operation of an anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system under low temperature conditions in winter, comprising the following methods: (1) A management unit was constructed based on five independent artificial wetland pools. The five artificial wetland pools were the first artificial wetland, the second artificial wetland, the third artificial wetland, the fourth artificial wetland and the fifth artificial wetland. The five artificial wetlands were arranged in sequence. 2 In the artificial wetland area covering an area of ​​2990.6m, five rectangular areas are set up along the length of the enclosure to construct five artificial wetlands. 2 Artificial wetland area, 3727.8m2 Artificial wetland area, 4413.6m 2 Artificial wetland area, 4560m 2 Artificial wetland area and 3946.32m 2 Constructed wetland area: The above-mentioned constructed wetland system is constructed, and the wetland substrate depth is 1.3m.

[0084] (2) In order to prevent the artificial wetland treatment bed from freezing in winter, a low-flow continuous water distribution method was used for treatment. The daily continuous water distribution volume of the first artificial wetland was only 2372.7 m 3 , continuous water distribution time 24h, the first wetland water distribution speed is 2372.7m 3 / 24h=98.86m 3 / h; the daily water supply of the second artificial wetland is 2827.1m 3 , the continuous water distribution time is 24h, and the water distribution speed of the second wetland is 2827.1 m 3 / 24h=117.80m 3 / h. The continuous daily water supply of the third artificial wetland is 3348.3m 3 , the continuous water distribution time is 24h, and the water distribution speed of the third wetland is 3348.3m 3 / 24h=139.51 m 3 / h; the fourth artificial wetland has a daily continuous water supply of 3458.3m 3 , continuous water distribution time 24h, the fourth wetland water distribution speed is 3458.3m 3 / 24h=144.096m 3 / h. The fifth artificial wetland has a daily continuous water supply of 2994m 3 , continuous water distribution time 24h, the fourth wetland water distribution speed is 2994m 3 / 24h=124.75m 3 / h. The total continuous water supply of the five artificial wetlands is 2372.7m 3 +2827.1m 3 +3348.3m 3 +3458.3m 3 +2994 m 3 =15000m 3 . This ensures that the tail water discharged from the sewage treatment plant during 24-hour operation can be effectively treated.

[0085] (3) Through the PLC control system, each artificial wetland pool is automatically controlled according to the water inlet time and water volume. Each artificial wetland pool is equipped with a solenoid valve and a flow meter. The tail water treated by the sewage treatment plant enters the water inlet pipe through the water inlet distribution valve, and is distributed to the artificial wetland through the water distribution network for purification. The flow meter feedback data is used to understand the impact of the water inlet flow at any time; (4) Plants in the entire artificial wetland are harvested before winter, and the harvested plants form a plant insulation layer about 2 cm thick on the surface of the wetland.

[0086] (5) In view of the special temperature in the northwest region, when the daytime temperature is above 16°C and the nighttime temperature is not lower than 5°C, the summer operation mode can be adopted, which is to operate the artificial wetland in a vertical downward flow with alternating dry and wet conditions and upper water distribution and bottom water discharge. Otherwise, the winter operation mode is adopted, which is to operate the artificial wetland in a vertical upward flow with low-flow continuous water distribution and bottom water distribution and upper water discharge.

[0087] The sewage treated by the artificial wetland is the tail water of the sewage after being treated by the sewage treatment plant. The water quality is Class A standard; the water flow rate is 15000m 3 / d.

[0088] The above water bodies are treated by artificial wetland system. In winter (November 13, 2023 to April 10, 2024), the wetland adopts the winter vertical upward flow artificial wetland mode with bottom water distribution and upper water discharge. In order to prevent the artificial wetland treatment bed from freezing in winter, low-flow continuous water distribution is adopted for treatment. The total continuous water distribution of the five artificial wetlands is 15,000m per day. 3 , continuous water distribution time is 24h, so as to ensure that the tailwater discharged from the sewage treatment plant in 24h operation can be treated. From April 11 to November 12, 2023, the temperature is high, and the wetland adopts the summer vertical downward flow artificial wetland mode with upper water distribution and bottom water discharge, and alternating dry and wet, and completes a water distribution cycle in 2 days. The total continuous water distribution of the five artificial wetlands is 15000m per day. 3 The continuous water distribution time is 48 hours, thus ensuring that the tail water discharged from the sewage treatment plant operating 24 hours a day can be treated.

[0089] Analysis of winter operation effect: Sampling was conducted monthly from July to September 2023 and from January to February 2024 to monitor the various water quality indicators of the wetland inlet and outlet. The detection of water quality indicators such as total phosphorus TP and total nitrogen TN were carried out using conventional methods in the field. The following results are the results of 5 sampling tests:

[0090] Comparison of the measured water quality data shows that the artificial wetland still has a certain removal effect on pollutants under different temperature conditions. By adopting the present invention, the stable operation of the artificial wetland in winter and summer can be guaranteed.

[0091] The above description is only a preferred example of the present invention and is not any formal or substantial limitation to the present invention. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. Any equivalent changes and modifications made to the above examples based on the essential technology of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system, characterized by: It comprises a treatment unit based on a plurality of artificial wetland pools arranged in sequence, wherein a water inlet and a water outlet are respectively arranged at both ends of each artificial wetland pool, a water inlet is arranged at the upper part and the bottom of the water inlet, a water outlet and an overflow are arranged at the bottom and the upper part of the water outlet, respectively, a water inlet pipe and a water distribution network are arranged at the upper part and the bottom of the water inlet, the water inlet is connected to the water inlet pipe, a water inlet distribution valve is arranged on the water inlet pipe, the water inlet pipe is connected to a water distribution pipe, the water distribution pipe is communicated with the water distribution network, a bottom water outlet pipe is arranged at the bottom of the water outlet, the bottom water outlet pipe passes through the water outlet, a water outlet regulating dam is arranged at the upper part of the water outlet, and the overflow is arranged at the upper part of the water outlet regulating dam.

2. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 1 is characterized by: The water distribution network is composed of a plurality of water distribution main pipes and a plurality of water distribution branch pipes. The water distribution main pipes are distributed along the direction of the water outlet. The water distribution branch pipes are respectively installed on both sides of the water distribution main pipes. The water distribution main pipes are joined to the water distribution branch pipes at a vertical angle, and each joining point is equidistant. The plurality of water distribution main pipes and the plurality of water distribution branch pipes together form a "W"-shaped pipe network, which completely covers the artificial wetland pool.

3. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 2 is characterized in that: A number of upper water distribution holes are equidistantly arranged at the bottom of the water distribution main pipe and the water distribution branch pipe of the upper water distribution network, and a number of bottom water distribution holes are equidistantly arranged on the upper part of the water distribution main pipe and the water distribution branch pipe of the bottom water distribution network; the upper water distribution holes are arranged 45° downward along the horizontal plane, and the opening centers of the two upper water distribution holes are 90° apart; the bottom water distribution holes are arranged 45° upward along the horizontal plane, and the opening centers of the two bottom water distribution holes are 90° apart.

4. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 1 is characterized in that: Each artificial wetland pool is provided with a PLC control system and a flow meter, and the water inlet and distribution valve and the flow meter are connected to the PLC control system.

5. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 1 is characterized in that: Aquatic plants are planted on the surface of the artificial wetland pool. The artificial wetland pool structure includes a filler layer, which includes a gravel layer with a particle size of 0.5 to 4 cm. The thickness of the filler layer is 100 to 110 cm.

6. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 5 is characterized by: The gravel layer one includes a bottom gravel cushion layer, a secondary bottom gravel layer, an intermediate gravel layer and a medium-coarse sand filter layer, wherein the gravel diameter of the bottom gravel cushion layer is 2-4cm and the thickness is 25cm, the gravel diameter of the secondary bottom gravel layer is 1-2cm and the thickness is 25cm, the gravel diameter of the intermediate gravel layer is 0.5-1cm and the thickness is 20cm, the gravel diameter of the medium-coarse sand filter layer is 0.5-2mm and the thickness is 30cm; the medium-coarse sand filter layer is filled with a water distribution layer filling layer, and the water distribution layer filling layer is formed by filling gravel with a diameter of 0.5-1cm and a thickness of 10cm around the pipes of the water distribution network.

7. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 1 is characterized by: The water outlet regulating dam includes a step-type wall and a first vertical wall panel, the step-type wall includes a transverse wall panel, a second vertical wall panel and a third vertical wall panel, the second vertical wall panel and the third vertical wall panel are respectively perpendicular to the transverse wall panel and are respectively arranged on the upper and lower sides of the transverse wall panel, the first vertical wall panel is arranged on the transverse wall panel and is located directly above the third vertical wall panel, and a plurality of holes are opened at the bottom of the first vertical wall panel.

8. The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system according to claim 7 is characterized in that: The water outlet end of the artificial wetland pool is provided with a water outlet channel, the upper part of the water outlet channel is provided with a water outlet pipe, the height of the water outlet pipe is the same as that of the horizontal wall panel, and a vent pipe is provided at the right bottom of the water outlet channel.

9. A method for treating tailwater of an anti-clogging and anti-freezing bidirectional flow vertical flow constructed wetland system, characterized in that: The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system described in any one of claims 1 to 8 is adopted, and the artificial wetland pool body adopts low-flow 24-hour continuous water distribution during low-temperature operation in winter, closes all upper water inlet distribution valves, opens all bottom water inlet distribution valves, and closes the gate at the outlet end of the artificial wetland pool body to realize the vertical upward flow artificial wetland operation with bottom water distribution and upper water outlet.

10. A method for treating tailwater of an anti-clogging and anti-freezing bidirectional flow vertical flow constructed wetland system, characterized in that: The anti-clogging and anti-freezing bidirectional flow vertical flow artificial wetland system described in any one of claims 1 to 8 is adopted, characterized in that: the artificial wetland pool adopts dry and wet alternation in summer operation, completes a water distribution cycle in two days, closes all bottom water inlet distribution valves, opens all upper water inlet distribution valves, and opens the water outlet gate to realize the vertical downward flow artificial wetland operation with upper water distribution and bottom water outlet.

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