Unpowered self-purification composite filter material tail water advanced treatment device

Abstract

The utility model discloses an unpowered self-purification composite filter material tail water advanced treatment device, and belongs to the technical field of sewage treatment. Comprising a water inlet buffer tank, a drop aeration tank, a constructed wetland and a water outlet well which are sequentially communicated according to a downward stepped structure, a composite filter material reaction tank is further arranged between the drop aeration tank and the constructed wetland, and the composite filter material reaction tank is filled with a composite filter material for adsorbing and degrading pollutants; the drop aeration tank is communicated with the upper part of the composite filter material reaction tank through a water inlet pipeline, and the bottom of the composite filter material reaction tank is communicated with the constructed wetland through a water outlet pipeline. According to the utility model, the composite filter material unit is additionally arranged between the drop aeration unit and the wetland unit in the traditional unpowered treatment device, so that the problem of blockage caused by the fact that the conventional filter material is arranged at the bottom of the constructed wetland is solved, and the whole water purification capacity of the device can be further improved by adjusting the type of the composite filter material and the like.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology, specifically relating to a non-powered self-purifying composite filter media tailwater deep treatment device. Background Technology

[0002] With the advancement of rural domestic sewage treatment, various non-powered or micro-powered sewage treatment equipment has been widely used. However, in actual operation, it has been found that due to the large fluctuations in the quantity and quality of rural sewage and limited management and maintenance capabilities, many effluents after conventional biological treatment still have many prominent problems. Not only do key water quality indicators such as COD, ammonia nitrogen, and total phosphorus in the effluent fail to consistently meet the Class A discharge standard, but most existing advanced treatment equipment also relies on electric power, which easily leads to difficulties in sharing electricity costs in rural areas. In addition, the lack of professional technicians for daily maintenance makes the equipment prone to blockages and failures. Furthermore, the complexity of traditional advanced treatment processes directly results in high operating costs, making it difficult to meet the needs of long-term operation and maintenance.

[0003] Patent application number 202320211450.X discloses a non-powered constructed wetland wastewater treatment device for slopes. It addresses the ecological treatment of urban or rural wastewater through a multi-stage treatment tank, cascading aeration platform, multi-stage constructed wetland, and effluent well arranged in a stepped structure. While this patent also mentions achieving non-powered water purification through a stepped structure, the cascading aeration platform is directly connected to the constructed wetland. Untreated wastewater enters the constructed wetland directly, leading to large particles of silt clogging it. Furthermore, harmful chemical components in the wastewater directly enter the constructed wetland, causing the water-purifying plants to deactivate, ultimately rendering the constructed wetland ineffective and significantly reducing the effluent treatment efficiency. Additionally, although the device includes a backwash pipe, this pipe still requires external power to achieve both backwashing and filter cleaning, contradicting the original intention of non-powered effluent treatment.

[0004] In summary, while existing technologies have proposed non-powered effluent treatment techniques using sloping, stepped designs, these treatment devices may experience maintenance difficulties or clogging and failure after long-term use. Furthermore, constructed wetlands alone cannot guarantee effluent compliance, especially when treating low-concentration, recalcitrant effluent, where conventional methods struggle to achieve ideal purification results. Currently, effective non-powered deep treatment methods are still lacking. Therefore, there is an urgent need for a power-free, maintenance-free treatment device capable of deep effluent purification, ensuring that the effluent consistently meets Class A standards. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a non-powered self-purifying composite filter media tailwater deep treatment device.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] A non-powered, self-purifying composite filter media effluent deep treatment device includes an inlet buffer tank, a cascading aeration tank, an artificial wetland, and an effluent well connected in a downward stepped structure. A composite filter media reaction tank is also provided between the cascading aeration tank and the artificial wetland. The composite filter media reaction tank is filled with composite filter media for adsorbing and degrading pollutants. The upper part of the cascading aeration tank and the composite filter media reaction tank are connected through an inlet pipe, and the bottom of the composite filter media reaction tank is connected to the artificial wetland through an effluent pipe.

[0008] This invention, based on existing non-powered constructed wetland wastewater treatment devices for slopes, adds a composite filter media reaction tank between the cascading aeration tank and the constructed wetland. This further enhances the filtration and purification effect of wastewater, allowing some silt and harmful substances to be intercepted by the composite filter media reaction tank, preventing them from directly entering the constructed wetland and damaging its wastewater purification effect, thereby extending the service life of the device. Specifically, the outlet of the cascading aeration tank is connected from above to the composite filter media reaction tank, and the outlet of the composite filter media reaction tank is connected from below to the constructed wetland. While the stepped structure of the device provides the flow power for the water, the water flows downwards under gravity within the composite filter media reaction tank, ensuring full contact with the composite filter media and achieving highly efficient filtration and purification of wastewater.

[0009] Preferably, the non-powered self-purifying composite filter media tailwater deep treatment device is further equipped with a sludge discharge system, including a number of siphon branch pipes spaced apart at the bottom of the composite filter media reaction tank, and a siphon main pipe connected to each siphon branch pipe. The siphon branch pipes have a number of sludge suction holes on their pipe walls. The siphon main pipe extends from bottom to top out of the composite filter media reaction tank. An inverted U-shaped water seal bend is connected to the water outlet end of the siphon main pipe. The water level at the outlet of the inverted U-shaped water seal bend is lower than the working water level in the composite filter media reaction tank.

[0010] Traditional wastewater treatment systems typically have a filter media layer at the bottom of the constructed wetland. Since the effluent often contains sediment, and the constructed wetland may experience sediment loss, the downward flow of water drastically increases the treatment load on the filter media layer, necessitating the installation of backflushing pipes within the filter media layer. However, to balance the wastewater treatment pressure, these backflushing pipes still require external high-pressure water pumps to flush away the sediment. Furthermore, because the filter media layer is located at the bottom of the constructed wetland, this flushing is often untimely and increases maintenance costs. This invention, in addition to a separate composite filter media reaction tank, also includes a sludge removal system. This system uses siphon action to remove sediment, and combined with the purification effect of the composite filter media, reduces sediment buildup and damage to the constructed wetland, synergistically improving the treatment effect of the effluent. Specifically, under gravity, sediment in the wastewater accumulates at the bottom of the composite filter media reaction tank. Several siphon branch pipes are installed at the bottom, with suction holes on the pipe walls to draw the sediment-laden wastewater into the siphon branch pipes. Each siphon branch pipe connects to the siphon main pipe, which extends upwards from the bottom to the outside of the composite filter media reaction tank. An inverted U-shaped water seal bend is connected to the outlet end. It is understood that the working liquid level described in this invention refers to a preset liquid level height that enables the composite filter media reaction tank to operate normally. The outlet liquid level at the inverted U-shaped water seal bend is lower than this working liquid level, creating a liquid level difference. Without any external force, the silt in the siphon branch pipes can be discharged out of the tank through the siphon main pipe solely through siphon action.

[0011] The siphon main pipe includes a first main pipe disposed at the bottom of the composite filter media reaction tank and a second main pipe that is vertically connected to the first main pipe; a plurality of siphon branch pipes are respectively vertically connected to the first main pipe, and the end of the second main pipe away from the first main pipe extends out of the composite filter media reaction tank and is connected to the inverted U-shaped water seal bend.

[0012] The first main pipe is also located at the bottom of the pool, and the siphon branch pipe is directly and vertically connected to the first main pipe. In actual operation, when the siphon is not activated or interrupted, the silt is collected through the siphon branch pipe and then flows into and temporarily stored in the first main pipe. After the siphon is activated, the sewage containing silt is quickly discharged out of the pool through the second main pipe, which is perpendicular to the first main pipe. Dividing the siphon main pipe into a first main pipe for temporary storage of silt and a second main pipe for rapid discharge optimizes the pipeline layout, reduces water flow resistance, ensures the stability and efficiency of siphon sludge discharge, and facilitates the installation and subsequent maintenance of the sludge discharge system.

[0013] Preferably, the inverted U-shaped water seal bend is equipped with a float level valve, which can preset the siphon start level as needed and achieve fully automatic sludge discharge. When the water depth in the composite filter media reaction tank increases to the set level due to blockage, the float level valve opens, and the sludge at the bottom of the tank is quickly discharged at a high flow rate through siphon action. When the water level drops to the set level, the float valve automatically closes to prevent all the sewage in the tank from being discharged due to siphon action, ensuring that only the sewage containing sludge at the bottom of the tank is discharged.

[0014] The composite filter media reaction tank is equipped with a guide plate embedded within the composite filter media. The inlet end of the guide plate is fixed to the side wall of the reaction tank, and water flows out through the outlet end of the guide plate and into the outlet pipe. The guide plate in the composite filter media area extends the wastewater path, allowing for better contact between the wastewater and the composite filter media.

[0015] Preferably, the guide plate includes a first guide plate, a second guide plate, and a third guide plate arranged sequentially from top to bottom at intervals. The sidewall of the composite filter media reaction tank includes an inlet sidewall and an outlet sidewall arranged opposite to each other. The outlet of the inlet pipe is opened on the inlet sidewall, and the inlet of the outlet pipe is opened on the outlet sidewall. The first guide plate and the third guide plate are both fixed on the inlet sidewall, and the second guide plate is fixed on the outlet sidewall.

[0016] The number and installation position of the guide plates are controlled to ensure that the water flows in an S-shape or inverted S-shape within the composite filter media. This preferred technical solution specifies only one water flow pattern: water flows into the tank from the inlet pipe and then sequentially passes through the first, second, and third guide plates. It is understood that those skilled in the art can adjust the installation method of the guide plates as needed to enhance the purification effect of the composite filter media, such as adjusting the number of guide plates, the angle between them and the sidewalls, and the spacing between the guide plates.

[0017] Preferably, the composite filter media is configured from top to bottom as follows: a water distribution layer, an adsorption layer, a filtration layer, a support layer, and a support layer. The filter media of the water distribution layer is gravel, the filter media of the adsorption layer is biochar particles, the filter media of the filtration layer is zeolite particles, the filter media of the support layer is ceramic particles, and the filter media of the support layer is gravel. The filter media layers are separated by permeable geotextile.

[0018] The selected fillers for each filter layer in the composite filter media reactor are as follows: the biochar adsorption layer primarily adsorbs organic matter and color; the zeolite filtration layer mainly removes ammonia nitrogen through ion exchange; and the ceramsite support layer primarily provides the biofilm adhesion area and facilitates further biodegradation. The sludge trapped in each filter layer settles to the support layer under gravity. At this point, the siphon branch pipe is buried within the support layer, and the sludge enters and is discharged through the suction holes on the siphon branch pipe. This multi-layered structure achieves a composite filtration effect while preventing pipe blockage by adjusting the particle size of the filler particles in each layer.

[0019] The inlet buffer tank is equipped with a filter grid to intercept floating debris. Each cascading step of the cascading aeration tank has an aeration grid on its surface in contact with the water flow to enhance aeration.

[0020] The outlet pipe is connected to the bottom of the constructed wetland, and the outlet well is connected to the upper part of the constructed wetland through a wetland pipe. Unlike existing constructed wetland treatment devices, this invention adjusts the inlet and outlet positions of the wetland, reducing pipe blockage caused by sediment from the constructed wetland that may be carried out by the downward flow of water.

[0021] Preferably, the constructed wetland is configured from top to bottom as follows: a planting soil layer, a coarse sand transition layer, and a gravel drainage layer. The outlet pipe is connected to the gravel drainage layer, and the wetland pipe is connected to the planting soil layer. Water-purifying plants are planted on the planting soil layer. The bottom layer of the constructed wetland is a gravel drainage layer. The gravel has a larger particle size than the sand in the middle layer, which does not affect the flow of wastewater or its entry into the coarse sand layer. After being treated by the composite filter media, the wastewater is further filtered through the gravel and coarse sand layers before entering the planting soil layer, effectively ensuring the growth of the water-purifying plants and thus improving the wastewater purification effect of the constructed wetland. It is understood that, to ensure the growth of the water-purifying plants, in addition to the above basic filler layer, a biological layer can be optionally added to enrich microorganisms, or fertilizers suitable for the selected water-purifying plants can be added to the planting soil layer.

[0022] The beneficial effects of this utility model are:

[0023] 1) This invention adds a composite filter media unit between the cascading aeration unit and the wetland unit in a traditional non-powered treatment device. This solves the clogging problem caused by conventional filter media being placed at the bottom of the artificial wetland and further enhances the overall water purification capacity of the device. Furthermore, the composite filter media is layered and graded, using a combination of functional filter media such as gravel, biochar, zeolite, and ceramic particles. This solves the problems of conventional effluent treatment filter media having single function, insufficient pollutant adsorption and degradation capacity, and a lack of microbial attachment carriers. It achieves a dual synergistic effect of physical adsorption and biofilm degradation through the composite filter media. Specifically, the biochar provides excellent attachment sites for microorganisms and forms a stable biofilm, efficiently removing pollutants such as COD, ammonia nitrogen, and total phosphorus from the effluent. Simultaneously, the biofilm has self-renewal capabilities, ensuring long-lasting and stable purification efficiency and guaranteeing that the effluent consistently meets the Class A standard.

[0024] 2) This utility model solves the problems of sludge accumulation and blockage of filter media pores at the bottom of the composite filter media reaction tank, sludge removal system consisting of siphon branch pipes, siphon main pipes and U-shaped water seal bends, which are equipped with a fully automatic siphon sludge removal system at the bottom of the composite filter media reaction tank. The problems of sludge accumulation and blockage of filter media pores at the bottom of the filter media tank, cumbersome and laborious manual sludge cleaning, and the need for external force to drive traditional sludge removal equipment are solved. The system achieves automatic sludge removal action without power by utilizing the internal water head difference of the device. The sludge accumulated at the bottom of the tank is continuously sucked through the sludge suction hole of the branch pipe. The float level valve and U-shaped water seal bend stabilize the sludge removal operation. No manual cleaning or operation is required, and no external power is needed to drive the system. This avoids filter media caking and blockage failure and ensures long-term smooth operation of the device.

[0025] 3) This utility model relies entirely on gravity flow without any electrical equipment, and the operating cost is close to zero. At the same time, the wetland water purification plants are integrated with the surrounding environment, combining purification function and landscape value. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the non-powered self-purifying composite filter media tailwater deep treatment device of this utility model.

[0027] Figure 2 This is a schematic diagram of the sludge removal system installed in the composite filter tank of this utility model.

[0028] Figure 3 This is a schematic diagram of the structure of the guide plate inside the composite filter tank of this utility model.

[0029] In the diagram, 1-Inlet buffer tank, 2-Cascading aeration tank, 3-Composite filter media reaction tank, 31-Composite filter media, 4-Constructed wetland, 5-Effluent well, 6-Water distribution layer, 7-Adsorption layer, 8-Filter layer, 9-Support layer, 10-Supporting layer, 11-Cascading steps, 12-Aeration grid plate, 13-Guide plate, 131-First guide plate, 132-Second guide plate, 133-Third guide plate, 14-Planting soil layer, 1 5-Coarse sand transition layer, 16-Gravel drainage layer, 17-Water purification plants, 18-Filter grid, 21-Siphon main pipe, 211-First main pipe, 212-Second main pipe, 22-Siphon branch pipe, 23-Sludge suction hole, 24-Inverted U-shaped water seal bend, 25-Float level valve, 26-Inlet pipe, 27-Outlet pipe, 28-Inlet sidewall, 29-Outlet sidewall, 30-Permeable geotextile, 32-Wetland pipe. Detailed Implementation

[0030] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0031] See Figure 1-3 This utility model provides a technical solution:

[0032] A non-powered self-purifying composite filter media tailwater deep treatment device includes an inlet buffer tank 1, a cascading aeration tank 2, an artificial wetland 4, and an outlet well 5 connected in a downward stepped structure. A composite filter media reaction tank 3 is also provided between the cascading aeration tank 2 and the artificial wetland 4. The composite filter media reaction tank 3 is filled with composite filter media 31 for adsorbing and degrading pollutants. The upper part of the cascading aeration tank 2 and the composite filter media reaction tank 3 are connected through an inlet pipe 26, and the bottom of the composite filter media reaction tank 3 is connected to the artificial wetland 4 through an outlet pipe 27.

[0033] The non-powered self-purifying composite filter media tailwater deep treatment device of this utility model is further provided with a sludge discharge system, including a number of siphon branch pipes 22 spaced apart at the bottom of the composite filter media reaction tank 3, and a siphon main pipe 21 connected to each siphon branch pipe 22. A number of sludge suction holes 23 are opened on the pipe wall of the siphon branch pipes 22. The siphon main pipe 21 extends from the bottom to the top of the composite filter media reaction tank 3. An inverted U-shaped water seal bend 24 is connected to the water outlet end of the siphon main pipe 21. The water outlet level of the inverted U-shaped water seal bend 24 is lower than the working water level in the composite filter media reaction tank 3.

[0034] The aforementioned siphon main pipe 21 includes a first main pipe 211 disposed at the bottom of the aforementioned composite filter media reaction tank 3 and a second main pipe 212 vertically connected to the aforementioned first main pipe 211; a plurality of the aforementioned siphon branch pipes 22 are respectively vertically connected to the aforementioned first main pipe 211, and the end of the aforementioned second main pipe 212 away from the aforementioned first main pipe 211 extends out of the aforementioned composite filter media reaction tank 3 and is connected to the aforementioned inverted U-shaped water seal bend 24.

[0035] A float level valve 25 is installed on the aforementioned inverted U-shaped water seal bend 24.

[0036] The composite filter media reaction tank 3 is provided with a guide plate 13 inside. The guide plate 13 is embedded in the composite filter media 31. The water inlet end of the guide plate 13 is fixed on the side wall of the composite filter media reaction tank 3. Water flows out through the water outlet end of the guide plate 13 and then flows into the water outlet pipe 27.

[0037] The aforementioned guide plate 13 includes a first guide plate 131, a second guide plate 132, and a third guide plate 133 arranged sequentially from top to bottom. The sidewall of the aforementioned composite filter media reaction tank 3 includes an inlet sidewall 28 and an outlet sidewall 29 arranged opposite to each other. The outlet of the aforementioned inlet pipe 26 is opened on the aforementioned inlet sidewall 28, and the inlet of the aforementioned outlet pipe 27 is opened on the aforementioned outlet sidewall 29. The aforementioned first guide plate 131 and the aforementioned third guide plate 133 are both fixed on the aforementioned inlet sidewall 28, and the aforementioned second guide plate 132 is fixed on the outlet sidewall 29.

[0038] The composite filter media 31 is arranged from top to bottom as follows: water distribution layer 6, adsorption layer 7, filtration layer 8, support layer 9 and support layer 10. The filter media of the water distribution layer 6 is gravel, the filter media of the adsorption layer 7 is biochar particles, the filter media of the filtration layer 8 is zeolite particles, the filter media of the support layer 9 is ceramic particles, and the filter media of the support layer 10 is gravel. The filter media layers are separated by permeable geotextile 30.

[0039] The aforementioned inlet buffer tank 1 is equipped with a filter grid 18, and each drop step 11 of the aforementioned drop aeration tank 2 is equipped with an aeration grid plate 12 on the surface that comes into contact with the water flow.

[0040] The aforementioned water outlet pipe 27 is connected to the bottom of the aforementioned artificial wetland 4, and the aforementioned water outlet well 5 is connected to the upper part of the aforementioned artificial wetland 4 through the wetland pipe 32.

[0041] The artificial wetland 4 is configured from top to bottom as follows: planting soil layer 14, coarse sand transition layer 15 and gravel drainage layer 16. The water outlet pipe 27 is connected to the gravel drainage layer 16, the wetland pipe 32 is connected to the planting soil layer 14, and water purification plants 17 are planted on the planting soil layer 14. Example 1

[0042] like Figure 1-3 As shown, Figure 1 This is a schematic diagram of the overall structure of the non-powered self-purifying composite filter media tailwater deep treatment device of this utility model. Figure 2 This is a schematic diagram of the sludge removal system installed in the composite filter tank of this utility model. Figure 3 This is a schematic diagram of the structure of the guide plate inside the composite filter tank of this utility model.

[0043] This embodiment 1 provides a non-powered, self-purifying composite filter media tailwater deep treatment device, such as... Figure 1 As shown, the device as a whole comprises an inlet buffer tank 1, a cascading aeration tank 2, a composite filter media reaction tank 3, an artificial wetland 4, and an effluent well 5, connected in a downward stepped structure. The working liquid level difference between each unit is 0.1-0.8m, allowing the water to flow entirely by gravity after entering the device. Specifically, the height difference between the inlet buffer tank 1 and the cascading aeration tank 2 is 0.3-0.5m, the height difference between the cascading aeration tank 2 and the composite filter media reaction tank 3 is 0.5-0.8m, the height difference between the composite filter media reaction tank 3 and the artificial wetland 4 is 0.2-0.4m, and the height difference between the artificial wetland 4 and the effluent well 5 is 0.1-0.2m. In practice, the inlet buffer tank 1 first receives effluent from upstream treatment units (such as sand bioreactors, septic tanks, etc.), and after the filter screen 18 intercepts floating debris, the wastewater flows into the cascading aeration tank 2. The cascading aeration tank 2 has a three-stage cascading platform 11 at the inlet, allowing natural aeration and oxygenation through gravity-driven water flow. Aeration grids 12 are laid on the surface of each cascading platform 11 to increase the turbulence of the water flow and improve oxygen transfer efficiency. After cascading aeration, the dissolved oxygen concentration in the water can increase to 2-3 mg / L, providing oxygen for subsequent biodegradation in the composite filter media reaction tank 3.

[0044] After aeration, the water enters the composite filter media reaction tank 3 through the inlet pipe 26, passing sequentially through the water distribution layer 6, adsorption layer 7, filtration layer 8, support layer 9, and support layer 10. Specifically, the water distribution layer 6 is filled with gravel with a particle size of 10-20mm and a thickness of 10-15cm, used for evenly distributing the incoming water; the adsorption layer 7 is filled with biochar particles with a particle size of 3-5mm and a thickness of 20-30cm. The biochar has an iodine adsorption value ≥800mg / g and a specific surface area ≥500m² / g, primarily used for adsorbing organic matter and providing a site for microbial attachment, and for the biodegradation of organic matter; the filtration layer 8 is filled with zeolite particles with a particle size of 2-4mm and a thickness of 20-30cm. The zeolite has a cation exchange capacity ≥15... The filter media has a concentration of 0 mmol / 100g and is primarily used to adsorb ammonia nitrogen and heavy metals. Ammonia nitrogen is adsorbed by zeolite particles through ion exchange, while nitrifying bacteria on the zeolite surface convert ammonia nitrogen into nitrate nitrogen. The support layer 9, filled with ceramic particles of 5-8 mm in diameter and 15-20 cm thick, supports the upper filter media and provides surface area for biofilm adhesion, further facilitating biodegradation and filtration to remove residual pollutants. The support layer 10, containing gravel of 20-40 mm in diameter and 10-15 cm thick, supports each filter media layer and collects the treated wastewater. A permeable geotextile 30 serves as a separator between the filter media layers to prevent mixing of different particle sizes.

[0045] like Figure 3 As shown, three guide plates 13 are fixed at intervals on the side wall of the composite filter media reaction tank 3. The first guide plate 131 and the third guide plate 133 are both fixed to the inlet side wall 28 with the inlet pipe 26, and the second guide plate 132 is fixed to the outlet side wall 29 with the outlet pipe 27. This causes the water to flow in a baffled pattern between the guide plates 13, extending the hydraulic residence time and ensuring that the composite filter media 31 achieves its full treatment effect. Specifically, the vertical spacing between adjacent guide plates 13 is 1 / 3 of the reaction zone height to ensure smooth water flow. It is understood that this embodiment, for example... Figure 1-3 As shown, the side walls of each treatment tank unit are vertical side walls at 90° to the horizontal plane. The installation of each guide plate 13 makes the water outlet end lower than the water inlet end, that is, the water outlet end is set downwards, and the angle between the water outlet end and its corresponding side wall is 100°, so that the hydraulic retention time is 5-6 hours.

[0046] like Figure 2As shown, the composite filter media reaction tank 3 is equipped with a siphon automatic sludge discharge system, including two main siphon pipes 21 and multiple branch siphon pipes 22. The branch siphon pipes 22 are perpendicular to the first main pipes 211 and are located within the support layer 10 at the bottom of the composite filter media reaction tank 3. The sidewalls of the branch siphon pipes 22 have several sludge suction holes 23 with a diameter of 5 mm, spaced 10 cm apart. A second main pipe 212 is vertically connected to the first main pipe 211. The second main pipe 212 extends upwards from the bottom of the composite filter media reaction tank 3 and has an inverted U-shaped water seal bend 24 at its outlet end. The outlet end of the inverted U-shaped water seal bend 24 is sealed with a liquid seal, the liquid level of which can be adjusted according to actual conditions. In this embodiment 1, when the sludge trapped by the composite filter media 31 layer accumulates to a certain amount in the support layer 10, the water level in the composite filter media reaction tank 3 rises, forming a water head difference of 20-30cm with the outlet end of the inverted U-shaped water seal bend 24, triggering the siphon effect. The sludge enters the siphon branch pipe 22 through the sludge suction hole 23, then gathers in the first main pipe 211, and is quickly discharged by the second main pipe 212.

[0047] A float level valve 25 is installed on the inverted U-shaped water seal bend 24. When the water depth in the composite filter media reaction tank 3 increases to the set level due to blockage, the float level valve 25 opens, and the sludge at the bottom of the composite filter media reaction tank 3 is quickly discharged at a high flow rate through siphon action. When the water level drops to the set level, the float level valve 25 automatically closes to prevent all the sewage in the tank from being discharged due to siphon action, ensuring that only the sewage containing sludge at the bottom of the composite filter media reaction tank 3 is discharged.

[0048] Water treated in the composite filter media reaction tank 3 enters the constructed wetland 4 through the effluent pipe 27, flowing from bottom to top, passing sequentially through the gravel drainage layer 16, the coarse sand transition layer 15, and the planting soil layer 14. Specifically, the gravel drainage layer 16 is 10-15cm thick and consists of gravel with a particle size of 10-20mm; the coarse sand transition layer 15 is 10-15cm thick and consists of coarse sand with a particle size of 0.5-2mm; the planting soil layer 14 is 15-20cm thick and consists of soil, humus, and slow-release fertilizer mixed in a mass ratio of 7:2:1, used for planting water-purifying plants 17. The water-purifying plants 17 are selected from one or more of reeds, cattails, and calamus. The plant roots can penetrate deep into the substrate layer to absorb nitrogen and phosphorus nutrients from the water, while providing an attachment site for microorganisms, forming a rhizosphere microbial community, which further stabilizes and purifies the effluent water quality. Water in the artificial wetland 4 flows through the planting soil layer 14 and is discharged from the wetland pipe 32 into the outlet well 5, where it is used to collect effluent that meets discharge standards.

[0049] The device in Example 1 was used to treat the effluent after conventional biological treatment. The influent water quality was as follows: COD: 80-120 mg / L, ammonia nitrogen: 25-40 mg / L, total phosphorus: 2-4 mg / L, SS: 30-50 mg / L.

[0050] After treatment by this device, the effluent quality is as follows: COD: 30-45 mg / L, ammonia nitrogen 5-8 mg / L, total phosphorus 0.3-0.5 mg / L, SS: 8-12 mg / L. All indicators meet the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002): COD≤50 mg / L, ammonia nitrogen≤5(8) mg / L, total phosphorus≤0.5 mg / L, SS≤10 mg / L. Example 2

[0051] The implementation of this embodiment 2 is consistent with that of embodiment 1, except that the composite filter media 31 in the composite filter media reaction tank 3 and the water purification plants 17 planted in the artificial wetland 4 are adjusted to obtain a better water purification effect. The specific implementation is as follows.

[0052] The composite filter media 31 is adjusted according to the influent water quality. When the influent ammonia nitrogen concentration is high, the thickness of zeolite particles in the filter layer 8 is increased to 30-40 cm; when the influent organic matter concentration is high, the thickness of biochar particles in the adsorption layer 7 is increased to 30-40 cm. A combination of various water-purifying plants, such as a mixture of reeds and cattails, or a mixture of reeds, cattails, and calamus, are planted in the planting soil layer 14 of the constructed wetland 4 to improve the stability of the ecosystem and the treatment effect.

[0053] In summary, this invention achieves deep purification of effluent through a combination of cascading aeration, adsorption filtration with composite filter media 31, and purification with constructed wetlands 4, resulting in consistently Class A effluent quality. The entire device relies entirely on gravity flow, requiring no electricity and resulting in extremely low operating costs. The use of large-diameter filter media and siphon automatic sludge removal enables maintenance-free operation. It is particularly suitable for deep treatment of effluent in rural areas that still cannot meet discharge standards after preliminary treatment.

[0054] The above description is merely a preferred embodiment of this utility model. It should be understood that this utility model is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. A non-powered self-purifying composite filter media tailwater deep treatment device, comprising an inlet buffer tank (1), a cascading aeration tank (2), an artificial wetland (4), and an outlet well (5) connected sequentially in a downward stepped structure, characterized in that: A composite filter media reaction tank (3) is also provided between the cascading aeration tank (2) and the constructed wetland (4). The composite filter media reaction tank (3) is filled with composite filter media (31) for adsorbing and degrading pollutants. The upper part of the cascading aeration tank (2) and the composite filter media reaction tank (3) are connected through an inlet pipe (26), and the bottom of the composite filter media reaction tank (3) is connected to the constructed wetland (4) through an outlet pipe (27).

2. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 1, characterized in that: A sludge discharge system is also provided, including a number of siphon branch pipes (22) spaced apart at the bottom of the composite filter media reaction tank (3), and a siphon main pipe (21) connected to each siphon branch pipe (22). A number of sludge suction holes (23) are opened on the pipe wall of the siphon branch pipe (22). The siphon main pipe (21) extends from the bottom to the top of the composite filter media reaction tank (3). An inverted U-shaped water seal bend (24) is connected to the water outlet end of the siphon main pipe (21). The water level at the outlet of the inverted U-shaped water seal bend (24) is lower than the working water level in the composite filter media reaction tank (3).

3. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 2, characterized in that: The siphon main pipe (21) includes a first main pipe (211) disposed at the bottom of the composite filter media reaction tank (3) and a second main pipe (212) vertically connected to the first main pipe (211); a plurality of siphon branch pipes (22) are vertically connected to the first main pipe (211), and the end of the second main pipe (212) away from the first main pipe (211) extends out of the composite filter media reaction tank (3) and is connected to the inverted U-shaped water seal bend (24).

4. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 2, characterized in that: A float level valve (25) is installed on the inverted U-shaped water seal bend (24).

5. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 1, characterized in that: The composite filter media reaction tank (3) is equipped with a guide plate (13), which is embedded in the composite filter media (31). The water inlet end of the guide plate (13) is fixed on the side wall of the composite filter media reaction tank (3). Water flows out through the water outlet end of the guide plate (13) and then flows into the water outlet pipe (27).

6. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 5, characterized in that: The guide plate (13) includes a first guide plate (131), a second guide plate (132) and a third guide plate (133) arranged sequentially from top to bottom. The side wall of the composite filter media reaction tank (3) includes an inlet side wall (28) and an outlet side wall (29) arranged opposite to each other. The outlet of the inlet pipe (26) is opened on the inlet side wall (28), and the inlet of the outlet pipe (27) is opened on the outlet side wall (29). The first guide plate (131) and the third guide plate (133) are both fixed on the inlet side wall (28), and the second guide plate (132) is fixed on the outlet side wall (29).

7. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 1, characterized in that: The composite filter media (31) are arranged from top to bottom as follows: water distribution layer (6), adsorption layer (7), filtration layer (8), support layer (9) and support layer (10). The filter media of the water distribution layer (6) is gravel, the filter media of the adsorption layer (7) is biochar particles, the filter media of the filtration layer (8) is zeolite particles, the filter media of the support layer (9) is ceramic particles, and the filter media of the support layer (10) is gravel. Each filter media layer is separated by a permeable geotextile (30).

8. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 1, characterized in that: The inlet buffer pool (1) is equipped with a filter grid (18), and each drop step (11) of the drop aeration pool (2) is equipped with an aeration grid plate (12) on the surface that comes into contact with the water flow.

9. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 1, characterized in that: The outlet pipe (27) is connected to the bottom of the artificial wetland (4), and the outlet well (5) is connected to the upper part of the artificial wetland (4) through the wetland pipe (32).

10. The non-powered self-purifying composite filter media tailwater deep treatment device according to claim 9, characterized in that: The artificial wetland (4) is configured from top to bottom as follows: planting soil layer (14), coarse sand transition layer (15) and gravel drainage layer (16). The water outlet pipe (27) is connected to the gravel drainage layer (16), the wetland pipe (32) is connected to the planting soil layer (14), and water purification plants (17) are planted on the planting soil layer (14).

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