Water treatment device based on a multi-stage soil infiltration system

Abstract

The utility model discloses a water treatment device based on multistage soil seepage system, including inlet and outlet water system and multistage soil infiltration tank, inlet and outlet water system includes by U type water pipe, water distributor and umbrella shaped refluxer. Multistage soil infiltration tank includes sleeve and the water distribution layer, filter unit and the receiving water-permeable layer that are arranged from top to bottom in sleeve. Filter unit includes a plurality of layers annular soil module layer, annular soil module layer includes by side wall I, bottom plate and side wall II annular U type screen disc that are composed, and set up in bottom plate and vertical cross section is annular soil block of U type, is provided with a plurality of through -holes on bottom plate. The device passes through modularization design, structural optimization and low carbon technology integration, realizes the efficient removal of mountain hilly region paddy field tail water nitrogen phosphorus, and has the characteristics of small floor space, low in cost, easy maintenance, zero carbon emission.

Description

Technical Field

[0001] This utility model belongs to the field of agricultural non-point source pollution control technology, and relates to sewage treatment devices, specifically a water treatment device based on a multi-stage soil infiltration system. Background Technology

[0002] The southwestern region of the upper reaches of the Yangtze River, a typical subtropical humid climate zone, is characterized by abundant annual precipitation and a high proportion of mountains and hills (>70%), making it an important rice-growing area in my country. However, long-term irrational agricultural practices, particularly the excessive application of nitrogen fertilizer (average application rate of approximately 280 kg N / ha) and phosphorus fertilizer (average application rate of approximately 100 kg P / ha), have led to significant exceedances of nitrogen and phosphorus loads in paddy field runoff (TN 8-12 mg / L, TP 0.5-1.2 mg / L, exceeding the Class III surface water standard by 7-11 times and 1.5-5 times, respectively). Furthermore, untreated agricultural runoff is directly discharged into surrounding water bodies, contributing 42% (TN) and 35% (TP) of the region's non-point source pollution load, not only exacerbating eutrophication in small watersheds but also causing continuous damage to the structure and function of the aquatic ecosystem in the upper reaches of the Yangtze River, seriously threatening the water environment security of the basin.

[0003] Agricultural non-point source pollution control technologies are characterized by their systematic, differentiated, and synergistic nature. Their technological system integrates source reduction, process interception, and end-of-pipe treatment measures. Technology selection must be tailored to local conditions, considering regional natural conditions and agricultural production characteristics to achieve a synergistic effect of pollutant reduction and ecological function enhancement. Due to the influence of factors such as climate and management, the effectiveness of these technologies is dynamic, necessitating the establishment of adaptive management mechanisms to ensure long-term operation. Existing non-point source pollution control technologies mainly fall into three categories: constructed wetlands, ecological ditches, and multi-stage soil infiltration systems.

[0004] Existing technologies for controlling non-point source pollution in paddy fields mainly include constructed wetlands, ecological ditches, and multi-stage soil infiltration systems. Constructed wetlands remove pollutants through the synergistic effect of substrates, plants, and microorganisms, but they suffer from problems such as large land area requirements, poor terrain adaptability, and low removal efficiency. Ecological ditches, as a "process blocking" technology, have a certain interception effect on nitrogen and phosphorus in farmland runoff, but their source control capabilities are limited in complex terrain. Multi-stage soil infiltration systems are suitable for treating farmland tailwater sources due to their small land area, but they are limited by low gas exchange efficiency within the system and the tendency for substrate blockage in water-saturated areas. They require mechanical aeration or periodic backwashing, resulting in high maintenance costs and technical requirements, making them unsuitable for the actual conditions in rural areas of Southwest China.

[0005] Therefore, there is an urgent need for a low-maintenance, low-cost, and low-carbon-emission paddy field wastewater treatment device suitable for mountainous and hilly areas, in order to overcome the application shortcomings of existing technologies in complex terrains and achieve efficient removal of nitrogen and phosphorus. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of existing non-point source pollution control technologies for paddy fields and to provide a water treatment device based on a multi-stage soil infiltration system that can be used for paddy field tailwater treatment. This device achieves efficient removal of nitrogen and phosphorus from paddy field tailwater in mountainous and hilly areas through modular design, structural optimization and low-carbon technology integration. It also features small footprint, low cost, easy maintenance and zero carbon emissions.

[0007] To solve the above-mentioned technical problems, the technical solution of this utility model is: a water treatment device based on a multi-stage soil infiltration system, including an inlet and outlet water system and a multi-stage soil infiltration tank;

[0008] The water inlet and outlet system includes a U-shaped water pipe consisting of an inlet pipe, a bottom pipe, and an outlet pipe; a water distributor installed at the outlet of the outlet pipe; and an umbrella-shaped return device installed in the lower part of the inlet pipe. A sludge discharge pipe is connected to the connection between the bottom pipe and the outlet pipe, and a valve is installed between the sludge discharge pipe and the U-shaped water pipe.

[0009] The multi-stage soil infiltration tank includes a sleeve and, from top to bottom, a water distribution layer, a filtration unit, and a permeable receiving layer arranged sequentially within the sleeve. The filtration unit includes several annular soil module layers. Each annular soil module layer includes an annular U-shaped screen composed of sidewall I, a bottom plate, and sidewall II, and an annular soil block with a U-shaped vertical cross-section, which is placed on the bottom plate. Several through holes are provided on the bottom plate. The annular soil blocks in two adjacent annular soil module layers are annular soil block I and annular soil block II, respectively. The outer annular wall of annular soil block I is in contact with sidewall I, and its inner annular wall has a gap with sidewall II. The inner annular wall of annular soil block II is in contact with sidewall II, and its outer annular wall has a gap with sidewall I. The thickness of the annular wall of annular soil block II is not less than the distance between the inner sidewall of annular soil block I and sidewall II. The U-shaped groove of the annular soil block and the space between it and the screen are filled with filter material.

[0010] The bottom pipe enters the multi-stage soil infiltration tank at the permeable layer, the outlet pipe passes through the central hole of the screen, the outlet is located in the water distribution layer, and the inlet of the U-shaped water pipe is higher than the outlet; a drainage pipe is also installed on the side wall of the sleeve at the permeable layer.

[0011] The aforementioned water treatment device based on a multi-stage soil seepage system also includes an auxiliary energy system. This system comprises solar panels and lighting and aeration equipment electrically connected to the solar panels. The solar panels are positioned above a sleeve, the aeration equipment is housed inside the outlet pipe, and the lighting is located outside the sleeve. The solar panels, positioned above the entire device, serve to store energy and provide rain protection. The solar panels are typically installed at an angle, which can be adjusted as needed, usually between 30° and 45°. Since this device is often installed near drainage ditches in paddy fields, the lighting provides safety, preventing pedestrians from falling into the ditches at night. The aeration equipment increases the dissolved oxygen concentration in the water, enhancing the nitrogen and phosphorus treatment effect of the device.

[0012] The aforementioned water treatment device based on a multi-stage soil infiltration system utilizes a U-shaped water pipe designed based on the principle of communicating vessels. This allows water to overflow from the distributor, flowing from top to bottom through a multi-layered filtration unit. Preferably, the inlet pipe of the U-shaped water pipe is located on the outer wall of the sleeve, and the outlet pipe passes through the central hole of the sieve disc, meaning the outlet pipe is located at the center of the sleeve (on the central axis). The diameter of the central hole of the sieve disc is compatible with the diameter of the outlet pipe. Since the bottom of the U-shaped water pipe may become clogged with silt, the bottom pipe is preferably inclined downwards to facilitate silt removal, with a sludge discharge pipe connected at its lowest point. During normal operation, the valve of the sludge discharge pipe is closed; when silt needs to be discharged, the valve opens to utilize the siphon effect for periodic sludge removal. Furthermore, silt may accumulate inside the outlet pipe located within the sleeve; an umbrella-shaped return valve is designed and placed inside the pipe to prevent silt from accumulating on the outer edge of the return valve and flowing upwards with the water. Finally, a drain pipe is positioned above the sludge discharge pipe. U-shaped water pipes and sleeves can be integrally molded to form a U-shaped pipe sleeve unit.

[0013] The aforementioned water treatment device based on a multi-stage soil seepage system, while ensuring that annular soil blocks I and II are nested and staggered in sequence, can have its specific number of layers set according to actual conditions. Preferably, the total number of annular soil module layers is an odd number and not less than 3 layers, with the bottom annular soil module layer being annular soil block I. More preferably, the total number of annular soil module layers is 5 layers.

[0014] In the aforementioned water treatment device based on a multi-stage soil seepage system, preferably, the height of the screen disc is greater than the height of the annular soil block. This allows a water layer to be formed between the bottom plate of the upper screen disc and the lower annular soil block, which is more conducive to the purification reaction of wastewater. The height of the screen disc (i.e., sidewall I and sidewall I height I) is preferably 20-30 cm, and the height of the annular soil block is preferably 15-20 cm.

[0015] The ring-shaped soil block can be a conventional wastewater treatment soil module in this field. This invention preferably uses a mixture of purple soil, biochar, and sponge iron in a mass percentage ratio of 50%–70%, 20%–30%, and 10%–20%. The particle sizes of the purple soil, biochar, and sponge iron are 2 mm, 2 mm, and 0.85 mm, respectively. The purple soil effectively retains nitrogen and phosphorus through physical adsorption by clay minerals, chemical fixation (such as calcium-magnesium bound phosphorus), and microbial activity, thus reducing nitrogen and phosphorus loss to some extent. The biochar, made from rapeseed straw and rice straw, has excellent carbon release and adsorption properties. Its complex surface pore structure provides polar or non-polar sites for adsorbing NH4 in the water. + -N and NO3 - -N provides carbon sources for soil microorganisms, optimizes the microbial community structure, and promotes nitrification and denitrification, further enhancing the nitrogen and phosphorus removal effects of the system.

[0016] The aforementioned water treatment device based on a multi-stage soil infiltration system primarily uses a permeable layer for system effluent discharge and to prevent system blockage. The preferred height of this permeable layer is 10-20 cm. While fulfilling the functions of system effluent discharge and preventing system blockage, the permeable layer can utilize conventional permeable layer fillers in the art; this invention preferably uses pebbles with a particle size of 10-15 mm as the filler. The function of the water distribution layer is to evenly distribute wastewater; the preferred height of this water distribution layer is 5-15 cm. While fulfilling the function of evenly distributing wastewater, the water distribution layer can utilize conventional water distribution layer fillers in the art; this invention preferably uses quartz sand as the filler, with 2-4 mm quartz sand evenly distributed. Furthermore, the water distributor is preferably a funnel-shaped water distributor.

[0017] The aforementioned water treatment device based on a multi-stage soil seepage system uses a screen disc primarily for accommodating annular soil blocks and laying filter media, while simultaneously allowing water to flow through into the next annular soil module layer. The screen disc has a central hole for the outlet pipe to pass through. This invention does not have special requirements regarding the size, height, or diameter of the evenly distributed holes in the screen disc; the design can be based on conventional needs in the field. In this invention, the screen disc is preferably a screen disc with several small holes having a diameter of 1-2 mm. The thickness and diameter of the screen disc can be set according to actual needs. The side wall II of the screen disc is in contact with the inner side wall of the sleeve.

[0018] The aforementioned water treatment device based on a multi-stage soil seepage system fills the U-shaped grooves of the annular soil blocks and the space between them and the screen disc and sleeve with filter media. The filter media primarily provides an aerobic environment for nitrifying bacteria to attach. This invention does not have specific limitations on the type of filter media; conventional filter media in the field can be used. This invention preferably uses natural zeolite with a particle size of 2-4 mm as the filter media. Nitrifying bacteria attach to the filter media.

[0019] The water treatment device based on a multi-stage soil infiltration system provided by this utility model has the following beneficial effects:

[0020] 1. This utility model adopts a modular design concept, with a compact overall structure and a small footprint. The designed footprint is only approximately 0.3m². 2 Compared to traditional constructed wetlands and ecological ditches, this method significantly saves land resources and is easy to transport and install, making it particularly suitable for the complex and varied terrain of mountainous and hilly areas. The device innovatively uses ring-shaped soil bricks with U-shaped grooves to construct a multi-stage soil infiltration system. The alternating layers of ring-shaped soil bricks not only increase the contact area between wastewater and the filter media, improving wastewater retention capacity, but also provide abundant attachment sites for microorganisms, enhancing pollutant removal efficiency.

[0021] 2. This invention utilizes the coupled regulation mechanism of pollutants and moisture in biochar-based ring-shaped soil blocks, adapting to influent hydraulics and pollution load to achieve anaerobic ammonia oxidation and short-cut nitrification / denitrification, significantly improving nitrogen removal efficiency. By introducing metal additives such as Fe into the soil module layer, a synergistic phosphorus removal mechanism of chemical precipitation and chemical adsorption is formed, reducing the total phosphorus concentration of the system to a low level and enhancing the phosphorus removal effect. The device is equipped with a bottom submerged zone, which enhances denitrification capacity and further improves the total nitrogen removal rate.

[0022] 3. This utility model employs photovoltaic conversion technology to efficiently convert solar energy into electrical energy and store it in an energy storage device. During the day, solar panels drive a high-efficiency aeration equipment to continuously aerate the water, providing sufficient dissolved oxygen for microorganisms and ensuring the smooth progress of pollutant removal. At night or during cloudy or rainy weather, the system automatically switches to energy storage power supply mode to provide clean electricity for LED lighting. This design achieves all-weather cascade utilization of solar energy, constructing a complete clean energy recycling system. It not only significantly improves the utilization efficiency of renewable energy but also achieves the energy conservation and emission reduction goals of zero-carbon and low-carbon emissions.

[0023] 4. This utility model utilizes locally sourced materials, selecting low-cost natural zeolite, straw (biochar), and iron powder as fillers, thus reducing the construction cost of the device. The fillers can be returned to the fields for resource recycling, extending the device's lifespan and reducing subsequent treatment costs. Compared to conventional wastewater treatment processes (with a treatment capacity of less than 100 tons), this device significantly reduces the cost per ton of water treated, demonstrating clear advantages in construction and operating costs. Simultaneously, it effectively removes nitrogen and phosphorus pollutants from paddy field runoff, reducing pollution to surrounding water bodies, improving the rural ecological environment, and contributing to the national strategies of "carbon peaking and carbon neutrality" and rural revitalization, demonstrating significant ecological, economic, and social benefits. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the water treatment device based on the multi-stage soil seepage system of this utility model;

[0025] Figure 2 yes Figure 1 Sectional view in the L direction;

[0026] Figure 3 yes Figure 2 AH direction sectional view;

[0027] Figure 4 This utility model is an operational hydraulic diagram based on a multi-stage soil seepage system.

[0028] Explanation of reference numerals in the attached drawings: 11. Water pipe; 12. Water distributor; 13. Sludge discharge pipe; 14. Drainage pipe; 21. Screen plate; 22. Annular soil block I; 23. Annular soil block II. Detailed Implementation

[0029] The technical solutions of various embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are part of the present invention.

[0030] This embodiment provides a water treatment device based on a multi-stage soil infiltration system, such as... Figure 1-3 As shown, it includes an inlet and outlet water system, a multi-stage soil infiltration pond, and an auxiliary energy system.

[0031] The inlet and outlet water system includes a U-shaped water pipe 11, a water distributor 12, and an umbrella-shaped return device. The multi-stage soil infiltration tank includes a sleeve and, from top to bottom, a water distribution layer, a filtration unit, and a permeable layer arranged within the sleeve. The auxiliary energy system includes solar panels and lighting and aeration equipment electrically connected to the solar panels.

[0032] The U-shaped water pipe 11 consists of an inlet pipe, a bottom pipe, and an outlet pipe. The water distributor 12 is a funnel-shaped distributor located at the outlet of the outlet pipe. An umbrella-shaped return valve is located inside the lower part of the inlet pipe, causing sediment to accumulate on the outer edge of the return valve, preventing it from flowing upwards with the water flow. The U-shaped water pipe 11 and the sleeve are integrally formed, creating a U-shaped pipe-sleeve unit. The inlet pipe of the U-shaped water pipe 11 is vertically positioned on the outer wall of the sleeve. The bottom pipe enters the multi-stage soil infiltration tank at the permeable layer. The outlet pipe passes through the central hole of the screen plate 21, with the outlet located in the water distribution layer, and the inlet of the U-shaped water pipe 11 is higher than the outlet. The bottom pipe is inclined downwards, and a sludge discharge pipe 13 is connected to it at the connection point with the outlet pipe. A valve is installed between the sludge discharge pipe 13 and the U-shaped water pipe 11. The sludge discharge pipe 13 is located at the lowest point of the bottom pipe. During normal operation, the valve of the sludge discharge pipe 13 is closed. When sludge needs to be discharged, the valve is opened to periodically discharge sludge using the siphon effect. A drain pipe 14 is also installed on the side wall of the sleeve at the point where it connects to the permeable layer. The drain pipe 14 is located above the sludge discharge pipe 13.

[0033] The water distribution layer has a height of 10cm and uses 2-4mm quartz sand as the filler.

[0034] The filtration unit comprises five annular soil module layers. Each annular soil module layer includes a sieve disc 21 and annular soil blocks with a U-shaped cross-section. The sieve disc 21 is an annular U-shaped sieve disc composed of sidewall I, a bottom plate, and sidewall II. The bottom plate has several through holes with a diameter of 1-2 mm. The annular soil blocks are placed on the bottom plate. The annular soil blocks in adjacent annular soil module layers are annular soil block I22 and annular soil block II23, respectively. The outer annular wall of annular soil block I22 is in contact with sidewall I, and its inner annular wall has a gap with sidewall II. The inner annular wall of annular soil block II23 is in contact with sidewall II, and its outer annular wall has a gap with sidewall I. The thickness of the annular wall of annular soil block II23 is not less than the distance between the inner sidewall of annular soil block I22 and sidewall II. Sidewall II of the sieve disc 21 is in contact with the inner sidewall of the sleeve. The height of the sieve disc 21 (i.e., the height of sidewall I and sidewall II) is 25 cm. The annular soil block is 16cm high. The U-shaped groove of the annular soil block and the space between it and the sieve plate 21 are filled with filter media. The filter media is natural zeolite with a particle size of 2-4mm, on which nitrifying bacteria are attached.

[0035] The ring-shaped soil blocks are made from purple soil, biochar, and sponge iron in a mass percentage ratio of 50%-70%, 20%-30%, and 10%-20%; the particle sizes of the purple soil, biochar, and sponge iron are 2mm, 2mm, and 0.85mm, respectively. The purple soil effectively retains nitrogen and phosphorus through physical adsorption by clay minerals, chemical fixation (such as calcium-magnesium bound phosphorus), and microbial activity, thus reducing nitrogen and phosphorus loss to some extent. The biochar, made from rapeseed and rice straw, has excellent carbon release and adsorption properties; its complex surface pore structure provides polar or non-polar sites for adsorbing NH4 in the water. + -N and NO3- -N provides carbon sources for soil microorganisms, optimizes the microbial community structure, and promotes nitrification and denitrification, further enhancing the nitrogen and phosphorus removal effects of the system.

[0036] The height of the permeable layer is 10cm, and pebbles with a particle size of 10-15mm are used as the filler for the permeable layer.

[0037] The solar panels of the auxiliary energy system are tilted above the sleeve via a bracket. The tilt angle is determined according to local sunlight conditions, generally between 30° and 45°, to prevent rainwater from entering. The aeration equipment is an oxygen pump installed inside the outlet pipe, while the lighting is installed outside the sleeve. Since this device is often installed next to drainage ditches in paddy fields, the lighting provides safety, preventing pedestrians from falling into the drainage ditches at night. The aeration equipment increases the dissolved oxygen concentration in the water, thereby enhancing the nitrogen and phosphorus treatment effect of this device.

[0038] The following provides a detailed description of the setup, operation, and maintenance of this device to further demonstrate its structural features:

[0039] 1. Equipment setup

[0040] 1.1 Material Preparation. Based on the design requirements, prepare the following materials: a U-shaped pipe sleeve assembly unit, materials for the water distribution layer and the permeable layer (i.e., sand and gravel of suitable particle size), a sieve tray 21, purple soil, biochar, sponge iron, and filter media (natural zeolite) required for the ring-shaped soil blocks. The ring-shaped soil blocks will be made using a special mold. Additionally, prepare solar panels, brackets for installing the solar panels, an oxygen pump, lighting, and other auxiliary equipment.

[0041] 1.2 Core Component Construction. First, place the sleeve in the selected location and ensure its stability. Inside the sleeve, lay the permeable layer from the bottom. The thickness is determined according to the actual situation, generally 10-20cm, but must not be lower than the outlet of the drainage pipe 14. Next, install the filter unit above the permeable layer. Lay the bottom layer (i.e., the first layer) of ring-shaped soil modules according to the design. First, place the sieve tray 21. The central hole of the sieve tray 21 passes through the outlet pipe. The diameter of the through holes on the bottom plate of the sieve tray 21 is controlled to ensure that most of the particles and gravel can be screened, while ensuring a sufficient number of sieve holes to reduce obstruction to water flow. After ensuring the screen trays 21 are placed parallel to each other, lay annular soil blocks I22 (the annular soil blocks are made of purple soil, biochar, and sponge iron in a dry weight ratio of 7:2:1). Place the annular soil blocks I22 on the screen trays 21 and tightly against the side wall I, with the U-shaped grooves facing upwards. Fill the U-shaped grooves and the empty space between the annular soil blocks and the screen trays 21 with natural zeolite with a particle size of 2-4 mm as filter media until the screen trays 21 are full. This completes the first layer of annular soil modules. Continue laying screen trays 21 on top, and alternately lay annular soil blocks II23 and I22 in the same manner to form five layers of annular soil modules. Note that odd-numbered layers are annular soil blocks I22, and even-numbered layers are annular soil blocks II23. Annular soil blocks II23 are tightly against the side wall II of the screen trays 21. This forms a structure where adjacent soil layers are interlocked rings. Finally, lay a water distribution layer above the filtration unit. The main structure of the device is now complete.

[0042] 1.3 Auxiliary Component Construction. Connect the solar panel to the pre-reserved portion at the top of the sleeve using a bracket. The solar panel should be placed at an angle, determined based on local sunlight conditions, typically 30°-45°, to prevent rainwater from entering. Connect an oxygen pump to the bottom of the solar panel, extending into the outlet pipe of the U-shaped water pipe 11 to increase the oxygen content of the incoming water. Simultaneously, connect a lighting lamp to the outside of the solar panel for illumination.

[0043] 2. Equipment Operation

[0044] 2.1 Hydraulic Operation

[0045] like Figure 4As shown, the wastewater from the paddy field flows into the inlet of the U-shaped water pipe 11 by gravity. The water flows within the U-shaped water pipe 11, and the umbrella-shaped sediment return device causes soil particles to settle at the lowest point of the U-shaped water pipe 11. The cleaning valve is opened periodically, and the settled sediment is discharged using a siphon effect. After entering the multi-stage soil infiltration tank, the water first passes through the water distribution layer for preliminary filtration of large particles. The pre-filtered water then enters the filtration unit, passing sequentially through each layer of annular soil modules. In the annular soil module layers, the purple soil in the annular blocks retains pollutants such as nitrogen and phosphorus through physical adsorption, chemical fixation, and microbial activity. Biochar provides a carbon source for microorganisms, promoting nitrification and denitrification, while sponge iron enhances phosphorus removal. Nitrifying bacteria attached to the filter media nitrify ammonia and other pollutants. Due to the structural design of the annular soil blocks with U-shaped grooves, the water flow path is increased, the hydraulic retention time is prolonged, and pollutants are fully reacted within the device. The water, after being treated by the filtration unit, is discharged from the drain pipe 14 installed on the side wall of the sleeve at the location of the permeable layer, thus achieving wastewater purification.

[0046] 2.2 Post-maintenance and management

[0047] 2.2.1 Regularly check the operation of each component of the device, including whether the U-shaped water pipe 11 is blocked, whether the sludge discharge pipe 13 valve is normal, whether the umbrella-shaped return valve is effective, whether the solar panel is working properly, and whether the oxygenation pump is operating well. Check the condition of the annular soil module layer in the filter unit, and observe whether there is any blockage or compaction.

[0048] 2.2.2 Regularly monitor the water quality of the influent and effluent, including indicators such as ammonia nitrogen, total phosphorus, and total nitrogen. Adjust the operating parameters of the device or perform corresponding maintenance based on the water quality monitoring results. Clean the U-shaped water pipe 11 and the silt and impurities inside the device regularly, according to actual operating conditions. Replace the annular soil module layer in the filter unit promptly when its performance deteriorates and affects pollutant removal. Due to its multi-layered structure, each level of the annular soil module layer can be removed and replaced sequentially. The waste annular soil module layer can be returned to the field as fertilizer.

[0049] 2.2.3 In cold regions during winter, take appropriate protective measures, such as heat preservation of the equipment, to prevent ice formation in the pipes and inside the equipment, which could affect the normal operation of the equipment.

[0050] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of this invention, and should be understood that the scope of protection of this invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on these technical teachings disclosed in this invention without departing from the essence of this invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A water treatment device based on a multi-stage soil seepage system, characterized in that: Includes inlet and outlet water systems and multi-stage soil infiltration ponds; The water inlet and outlet system includes a U-shaped water pipe (11) consisting of an inlet pipe, a bottom pipe and an outlet pipe, a water distributor (12) installed at the outlet of the outlet pipe and an umbrella-shaped return device installed in the lower part of the inlet pipe. A sludge discharge pipe (13) is connected to the connection between the bottom pipe and the outlet pipe. A valve is installed between the sludge discharge pipe (13) and the U-shaped water pipe (11). The multi-stage soil infiltration tank includes a sleeve and a water distribution layer, a filtration unit, and a permeable receiving layer arranged sequentially from top to bottom inside the sleeve; the filtration unit includes several annular soil module layers; the annular soil module layer includes an annular U-shaped screen (21) composed of sidewall I, a bottom plate, and sidewall II, and annular soil blocks with a U-shaped vertical cross-section set on the bottom plate, the bottom plate having several through holes; the annular soil blocks in two adjacent annular soil module layers are annular soil block I (21) and annular soil block II (21). 2) and annular soil block II (23), wherein the outer ring wall of the annular soil block I (22) is in contact with the side wall I and its inner ring wall is in contact with the side wall II, and the inner ring wall of the annular soil block II (23) is in contact with the side wall II and its outer ring wall is in contact with the side wall I, and the thickness of the ring wall of the annular soil block II (23) is not less than the distance between the inner side wall of the annular soil block I (22) and the side wall II; the U-shaped groove of the annular soil block and the space between it and the sieve plate (21) are filled with filter material; The bottom pipe enters the multi-stage soil infiltration tank at the receiving permeable layer, the outlet pipe passes through the center hole of the screen (21), the outlet is located in the water distribution layer, and the inlet of the U-shaped water pipe (11) is higher than the outlet; a drain pipe (14) is also provided on the side wall of the sleeve at the receiving permeable layer.

2. The water treatment device based on a multi-stage soil seepage system according to claim 1, characterized in that: The device also includes an auxiliary energy system, which includes a solar panel and a lighting device and an aeration device electrically connected to the solar panel. The solar panel is located above the sleeve, the aeration device is installed inside the water outlet pipe, and the lighting device is installed outside the sleeve.

3. The water treatment device based on a multi-stage soil seepage system according to claim 1, characterized in that: The bottom pipe of the U-shaped water pipe (11) is inclined, and the mud discharge pipe (13) is connected at the lowest point of the bottom pipe. The mud discharge pipe (13) is located below the drain pipe (14).

4. The water treatment device based on a multi-stage soil seepage system according to claim 1, characterized in that: The total number of annular soil module layers is not less than 3 and is an odd number, and the bottom annular soil module layer is annular soil block I (22).

5. The water treatment device based on a multi-stage soil seepage system according to claim 4, characterized in that: The total number of layers in the ring-shaped soil module is 5.

6. The water treatment device based on a multi-stage soil seepage system according to claim 1, characterized in that: The height of the permeable layer is 10-20cm.

7. The water treatment device based on a multi-stage soil seepage system according to claim 1, characterized in that: The height of the water distribution layer is 5-15cm.

8. The water treatment device based on a multi-stage soil seepage system according to claim 1, characterized in that: The height of the sieve disc (21) is 20-30cm, and the height of the annular soil block is 15-20cm.

9. The water treatment device based on a multi-stage soil seepage system according to any one of claims 1-8, characterized in that: The water distributor (12) is a trumpet-shaped water distributor (12).

10. The water treatment device based on a multi-stage soil seepage system according to any one of claims 1-8, characterized in that: The diameter of the through holes on the bottom plate of the sieve disc (21) is 1-2 mm.

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