Rural domestic sewage treatment system and method

Abstract

The invention discloses a rural domestic sewage treatment system and method, and relates to the technical field of sewage treatment equipment.The rural domestic sewage treatment system comprises a concrete base frame, a diversion trench, a pretreatment unit, an advanced treatment unit and a biological treatment unit; the concrete base frame is provided with three layers of concrete floor slabs from top to bottom and fixedly connected through concrete supporting columns, the output end of the diversion trench faces the input end of the pretreatment unit, the pretreatment unit is arranged on the uppermost concrete floor slab, and the deep treatment unit is arranged on the middle concrete floor slab. The biological treatment unit is arranged on the lowermost concrete floor, an axial flow pump is integrated in the diversion trench, the pretreatment unit comprises a floating object intercepting pond, a sedimentation pond and a PH value adjusting pond which are sequentially communicated, the deep treatment unit comprises a nitrification tank and an aeration system, and the biological treatment unit comprises an ecological filter. The device has the effects of effectively utilizing the limited occupied area and reducing the operation cost and the maintenance requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment equipment, and in particular to a rural domestic sewage treatment system and method. Background Technique

[0002] At present, rural domestic sewage treatment technologies are mainly divided into two modes: centralized and decentralized. The centralized system relies on large-scale pipe networks and sewage treatment plants, with huge initial investments and high long-term maintenance difficulties; although the decentralized system has a lower initial investment, the treatment effect fluctuates greatly, making it difficult to meet the increasingly strict environmental protection regulations.

[0003] Currently, constructed wetlands, anaerobic-aerobic combined processes, and integrated sewage treatment equipment are the main technical means for rural domestic sewage treatment. Constructed wetlands are favored for their low investment and easy operation. However, their significant land occupation problem and the resulting increase in operating costs and maintenance requirements limit their application to a certain extent. Summary of the Invention

[0004] This application provides a rural domestic sewage treatment system and method, which can effectively utilize the limited floor area and reduce the operating costs and maintenance requirements.

[0005] The rural domestic sewage treatment system and method provided by this application adopt the following technical solutions: A rural domestic sewage treatment system and method, wherein the rural domestic sewage treatment system includes a concrete base frame, a diversion channel, a pretreatment unit, a deep treatment unit, and a biological treatment unit; the concrete base frame is provided with three layers of concrete floor slabs from top to bottom and is fixedly connected by concrete columns, the output end of the diversion channel faces the input end of the pretreatment unit, the pretreatment unit is arranged on the topmost concrete floor slab, the deep treatment unit is arranged on the middle concrete floor slab, the biological treatment unit is arranged on the lowermost concrete floor slab, an axial flow pump is integrated inside the diversion channel, the pretreatment unit includes a floating matter interception pool, a sedimentation tank, and a pH value adjustment pool connected in sequence, the deep treatment unit includes a nitrification tank and an aeration system, and the biological treatment unit includes an ecological filter tank.

[0006] Preferably, a planting area is arranged on the inner wall of the nitrification tank, planting soil is filled in the planting area to form a planting area soil layer, and plants with developed root systems are planted in the planting area soil layer, and a permeable layer is arranged on the inner wall of the planting area soil layer of the nitrification tank.

[0007] Preferably, the permeable layer includes stone grains and activated carbon blocks, the diameter of the stone grains is larger than the diameter of the activated carbon blocks, and an artificial wetland is formed at the top of the planting area.

[0008] Preferably, the surface of the artificial wetland is covered with a biochar layer.

[0009] Preferably, a shaping net surface layer is arranged inside the inner circle of the permeation layer, a positioning ring for fixing the shaping net surface layer is arranged at the top of the permeation layer, a reinforcing collar is arranged inside the inner circle of the positioning ring, and a cobweb-shaped combined sleeve is arranged at the bottom inside the reinforcing collar.

[0010] Preferably, the cobweb-shaped combined sleeve is connected to the aeration system, and aeration holes are evenly distributed on the surface of the combined sleeve.

[0011] Preferably, a plurality of filter net rings are coaxially arranged inside the ecological filter tank, a mixed medium layer is filled between adjacent filter net rings, the mixed medium layer includes mixed pine needle soil, granular soil and sandy soil, and earthworms are arranged inside the mixed medium layer.

[0012] Preferably, the cross section of the filter net ring is in a stepped shape, the density of earthworms in the mixed medium layer is 100 - 300 per square meter, and the diameter of the filter net ring gradually increases from top to bottom.

[0013] Preferably, the earthworms achieve sewage purification by feeding on the organic matter in the mixed medium layer, and the excrement produced by the earthworm activities forms a cyclic regeneration structure with the mixed medium layer.

[0014] Preferably, a rural domestic sewage treatment method, based on the above rural domestic sewage treatment system, its treatment steps include: S1: Sewage feeding; Domestic sewage is discharged into the inside of the diversion trough through the sewage system, and under the action of the axial flow pump, the sewage at the low position is lifted to the inside of the floating matter interception tank at the high position; S2: Sewage pretreatment; Through the grid arranged in the floating matter interception tank, it is used to filter out the floating matter in the sewage. After intercepting the floating matter, the sewage enters the inside of the sedimentation tank. Through the sedimentation of the sedimentation tank, the supernatant produced after sedimentation is efficiently introduced into the subsequent pH adjustment tank to achieve mud - water separation and obtain the pretreated sewage; S3: Sewage advanced treatment; The pretreated sewage enters the inside of the nitrification tank. The nitrification and denitrification are coupled together. Through the participation of plants, a highly efficient nitrogen removal system is formed; the aeration system ensures the oxygen required for nitrification, the planting area soil layer provides the surface area required for the attachment and growth of microorganisms, and the plant roots further promote denitrification and nitrogen absorption; the pH adjustment tank ensures that the nitrification reaction proceeds at an appropriate pH value; through these synergistic effects, the ammonia nitrogen content in the water can be effectively reduced, and the advanced treated sewage can be obtained; S4: Sewage biological treatment; The deeply treated sewage enters the ecological filter. Earthworms further purify the sewage by ingesting and digesting organic matter. At the same time, the activities of earthworms can loosen the soil, improve the water permeability of the filter, and obtain the sewage after biological treatment. S5: Sewage discharge; The sewage after biological treatment is centrally guided to the water collection tank arranged at the bottom of the ecological filter through the bottom output end of the ecological filter, and the purified sewage is uniformly discharged through the water collection tank.

[0015] In summary, the present application has the following beneficial effects: 1. Through the axial flow pump arranged in the diversion channel, the sewage at a low position is lifted to the inlet of the pretreatment unit at a high position, realizing vertical transportation from bottom to top, and accurately guiding the sewage into the interior of the pretreatment unit. Subsequently, the sewage flows through the deep treatment unit and the biological treatment unit in sequence, completing the processes of deep purification and biodegradation. Finally, the treated sewage will be discharged into the water collection tank located below the concrete base through the drain outlet at the bottom of the biological treatment unit. The most core principle of this layout is to utilize gravity flow. The sewage starts from the upper pretreatment unit and naturally flows downward to the lower biological treatment unit and then to the deep treatment unit by gravity. By setting three floors, the three-dimensional space utilization of the sewage treatment system is realized. This hierarchical arrangement can effectively utilize the limited floor area; moreover, by using the height difference, the sewage can flow from one treatment unit to the next by gravity, reducing the use of water pumps, and lowering the operation cost and maintenance requirements.

[0016] 2. The coupled vertical flow constructed wetland is adopted. An aeration system is arranged at the bottom of the wetland to increase the dissolved oxygen and promote the nitrification reaction. At the same time, plants with developed root systems, such as canna and reed, are planted, and the nitrification and denitrification effects of the plant roots are used to remove ammonia nitrogen. In addition, a layer of biochar is covered on the surface of the wetland to adsorb ammonia nitrogen and provide a carrier for microbial attachment. In short, the aeration system increases the dissolved oxygen and promotes nitrification; the plant roots provide a place for nitrification and denitrification, and the biochar layer adsorbs ammonia nitrogen and provides a microbial carrier. The three work together to achieve efficient removal of ammonia nitrogen.

[0017] 3. Through the earthworms arranged in the ecological filter, the earthworms feed on the organic matter in the sewage and decompose it through digestion, reducing the organic pollutants in the water; the activities of the earthworms can loosen the soil, increase the water permeability and aeration of the soil, which is beneficial to the growth of plant roots and the activities of microorganisms. Description of the Drawings

[0018] Figure 1 is the overall structural schematic diagram of the rural domestic sewage treatment system in Embodiment 1; Figure 2 is the internal structural schematic diagram of the pretreatment unit in Embodiment 2; Figure 3 It is a schematic diagram of the overall internal structure of the advanced treatment unit in Embodiment 3; Figure 4 It is an exploded view of the internal structure of the advanced treatment unit in Embodiment 3; Figure 5 It is a schematic diagram of the overall structure of the biological treatment unit in Embodiment 4; Figure 6 It is a flow chart of the rural domestic sewage treatment method in Embodiment 5; Explanation of reference numerals: 1, concrete base frame; 11, concrete floor slab; 12, concrete pillar; 13, concrete staircase; 2, pretreatment unit; 21, floating matter interception tank; 22, sedimentation tank; 23, pH adjustment tank; 24, notch; 25, drainage trough; 3, advanced treatment unit; 31, nitrification tank; 32, aeration system; 33, planting area soil layer; 34, permeable layer; 35, biochar layer; 36, positioning ring; 37, reinforcement collar; 38, combined casing; 4, biological treatment unit; 41, ecological filter tank; 42, filter mesh ring; 43, mixed medium layer; 5, diversion trough; 6, axial flow pump; 7, water collection trough. Detailed implementation manners

[0019] The present application will be further described in detail below with reference to the drawings. It is necessary to point out here that the following detailed implementation manners are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content. Embodiment

[0020] The present invention discloses a rural domestic sewage treatment system and method, as Figure 1 shown. Among them, the rural domestic sewage treatment system includes a concrete base frame 1. The concrete base frame 1 provides a strong structural support to ensure the stability and durability of the sewage treatment system. Especially in rural areas, the geological conditions may not be as good as those in cities, so a strong foundation is crucial. The concrete base frame 1 includes three layers of concrete floor slabs 11 arranged from top to bottom, and the three layers of concrete floor slabs 11 are fixedly connected by concrete pillars 12. By setting three floor slabs, the three-dimensional space utilization of the sewage treatment system is realized. The following different treatment units can be arranged in layers, and this layered arrangement can effectively utilize the limited floor area. Moreover, by using the height difference, sewage can flow from one treatment unit to the next by gravity, reducing the use of pumps and lowering the operation cost and maintenance requirements. A concrete staircase 13 is also arranged between the three layers of concrete floor slabs 11, and the concrete staircase 13 facilitates the staff to go up and down for maintenance of each treatment unit.

[0021] As Figure 1As shown in the figure, further, a pretreatment unit 2, a deep treatment unit 3, and a biological treatment unit 4 are respectively arranged corresponding to the three-layer concrete floor slabs 11 from top to bottom; the most core principle of this layout is to utilize gravity flow. The sewage starts from the upper pretreatment unit 2 and naturally flows downward to the lower biological treatment unit 4 by gravity, and then to the deep treatment unit 3, without or reducing the use of water pumps.

[0022] As Figure 1 shown in the figure, on one side of the concrete base frame 1, a diversion trough 5 is stably assembled, and the output port of the diversion trough 5 is precisely docked with the input port of the pretreatment unit 2. An axial flow pump 6 is integrated inside the diversion trough 5, and its function is to efficiently lift the sewage in the diversion trough 5, lift the sewage at a low position to the entrance of the high-position pretreatment unit 2, realize vertical transportation from bottom to top, and precisely guide the sewage into the pretreatment unit 2. Subsequently, the sewage flows through the deep treatment unit 3 and the biological treatment unit 4 in sequence to complete the processes of deep purification and biodegradation. Finally, the treated sewage will be discharged into the water collection tank 7 located below the concrete base frame 1 through the drain outlet at the bottom of the biological treatment unit 4. Embodiment

[0023] As Figure 1 and Figure 2 shown in the figure, specifically, according to the sewage discharge path, the pretreatment unit 2 includes a floating matter interception tank 21, a sedimentation tank 22, and several pH adjustment tanks 23 fixed on the topmost concrete floor slab 11. The output end of the diversion trough 5 faces the floating matter interception tank 21, and a grille is arranged in the floating matter interception tank 21 to filter out the floating matter in the sewage. The sewage after intercepting the floating matter enters the interior of the sedimentation tank 22. Through the alum adding device in the sedimentation tank 22, alum is added to the sedimentation tank 22 to assist in the sedimentation of the sewage. The sedimentation tank 22 is in a long strip structure, and a notch 24 is provided at the top of the sedimentation tank 22. Several inclined drainage troughs 25 are provided at the notch 24 of the sedimentation tank 22. The drainage troughs 25 are inclined towards the top input port of the pH adjustment tank 23, and the pH adjustment tanks 23 are arranged in one-to-one correspondence with the drainage troughs 25. The pH adjustment tanks 23 are used to adjust the pH value of the sewage so that it can meet the discharge standard.

[0024] As Figure 2As shown in the figure, the diversion channel 5 guides the sewage into the pretreatment system. The floating matter interception pool 21 physically intercepts larger floating matters in the sewage through a grid, preventing subsequent equipment from being blocked or the treatment efficiency from decreasing. The sewage after intercepting the floating matters enters the sedimentation tank 22. The addition of alum plays a flocculation role, causing the suspended particles in the sewage to aggregate into larger flocs, accelerating the sedimentation process. And the long-strip sedimentation tank 22 is conducive to the flocs in the sewage settling to the bottom. The design of the notch 24 at the top and the inclined drainage trough 25 enables the supernatant to be efficiently guided into the subsequent pH adjustment tank 23, realizing the separation of mud and water. The pH adjustment tank 23 is used to adjust the pH value of the sewage to meet the national or local discharge standards. The specific adjustment method may include adding acidic or alkaline substances to neutralize the pH value of the sewage.

[0025] As Figure 2 shown in the figure, through multi-stage treatments such as floating matter interception, sedimentation, and pH adjustment, it is possible to effectively remove suspended solids, solid particles, and harmful substances in the sewage, reducing the pollution load. The use of flocculants can accelerate the sedimentation speed, shorten the treatment time, and improve the treatment efficiency. Embodiment

[0026] In the concentrated livestock and poultry breeding area, a large amount of breeding wastewater is directly discharged without treatment, resulting in a serious over-standard of the ammonia nitrogen concentration in the water body and causing damage to the aquatic ecosystem. The advanced treatment unit 3 is used to solve the technical problems of "high operating cost of the traditional nitrification and denitrification process and unstable treatment effect of the ecological pond" proposed in this embodiment. It is an ecological treatment system that can efficiently remove high-concentration ammonia nitrogen, and has low operating cost, simple maintenance, and small floor area.

[0027] As Figure 3 shown in the figure, specifically, the advanced treatment unit 3 includes a nitrification tank 31 and an aeration system 32 arranged in the nitrification tank 31. The aeration system 32 is used to increase the dissolved oxygen and promote the nitrification reaction. The nitrification tank 31 is located directly below the pH adjustment tank 23, and the output end of the pH adjustment tank 23 faces the top input end of the nitrification tank 31. A planting area with a thickness of 3 - 6 m is arranged on the inner wall of the nitrification tank 31, which is filled with the planting area soil layer 33 of the nitrification tank 31, and plants with developed root systems, such as cannas and reeds, are planted in the planting area soil layer 33, and the nitrification and denitrification effects of the plant roots are used to remove ammonia nitrogen.

[0028] As Figure 3 shown in the figure, the nitrification reaction consumes alkalinity, resulting in a decrease in pH value. The pH adjustment tank 23 adjusts the pH value to a suitable range and then guides the water into the nitrification tank 31 to ensure the activity of nitrifying bacteria.

[0029] As Figure 3As shown, the aeration system 32 injects air into the nitrification tank 31 to increase the dissolved oxygen (DO) in the water. Under aerobic conditions, nitrifying bacteria (such as nitrite bacteria and nitrate bacteria) living in the soil layer 33 of the planting area will gradually oxidize ammonia nitrogen (NH4⁺). First, nitrite bacteria oxidize ammonia nitrogen into nitrite (NO2⁻), and then nitrate bacteria oxidize nitrite into nitrate (NO3⁻). This process requires oxygen, so aeration is crucial.

[0030] As Figure 3 shown, deep in the soil layer 33 of the planting area, due to limited oxygen penetration, a local anaerobic or anoxic environment will be formed. Denitrifying bacteria (such as Bacillus denitrificans) use organic carbon sources to reduce nitrate (NO3⁻) to nitrogen gas (N2) under anaerobic or anoxic conditions, and the nitrogen gas is released into the atmosphere in the form of gas. The environment around the plant roots is often more conducive to the occurrence of denitrification. In addition to providing a surface for microbial attachment, plant roots can also absorb a part of nitrate and ammonia nitrogen from the water as nutrients, directly participating in nitrogen removal. At the same time, the respiration of plant roots consumes oxygen, further promoting the progress of denitrification.

[0031] As Figure 3 shown, furthermore, plants with developed roots such as canna and reed can directly absorb ammonia nitrogen and nitrate from the water as nutrients required for growth, thereby reducing the nitrogen content in the water. The nitrogen element absorbed by the plants will be transferred to various parts of the plants, and the nitrogen element will be removed from the system by harvesting the above-ground parts of the plants.

[0032] As Figure 4 shown, a permeable layer 34 is provided on the inner wall of the soil layer 33 of the planting area of the nitrification tank 31. The permeable layer 34 is a gravel layer with a thickness of 1 - 2 m. The gravel layer is composed of activated carbon blocks and stone grains with a diameter of 1 - 4 cm, and the diameter of the stone grains is larger than that of the activated carbon blocks. While the stone grains in the gravel layer enhance the water permeability, they can effectively prevent the soil in the planting area from being directly immersed in the water, block the water flow from washing away the soil, and cause water pollution. The activated carbon blocks in the gravel layer are used to adsorb impurities in the water quality, further ensuring the purification effect of the water flow.

[0033] As Figure 4 shown, the main function of the gravel layer is to enhance water permeability. There are gaps between the larger stone grains, enabling the water flow to penetrate quickly, avoiding the soil layer 33 of the planting area from being immersed in water for a long time. Thereby, it can block the water flow from directly impacting the soil layer 33 of the planting area, prevent soil particle loss, avoid water body turbidity, and reduce water pollution.

[0034] As Figure 4As shown, the activated carbon block has a developed pore structure and can adsorb impurities such as organic matter, pigments, odor substances, and heavy metal ions in water, reducing indicators such as COD and BOD of the water body and playing a certain purification role. Both the activated carbon and gravel provide attachment surfaces for microorganisms, facilitating the growth and reproduction of microorganisms, forming a biofilm, and thus promoting the biodegradation of pollutants.

[0035] As Figure 4 shown, by setting a gravel infiltration layer 34 on the inner wall of the planting area of the nitrification tank 31 and adding activated carbon blocks, it can effectively protect the soil, improve water quality, optimize hydraulic conditions, and promote biodegradation, which is an economical and effective sewage treatment method.

[0036] As Figure 4 shown, further, the water flow is immersed in the soil layer 33 of the planting area of the nitrification tank 31, and an artificial wetland is formed on the upper surface of the soil layer 33 of the planting area. A biochar layer 35 with a thickness of 10 - 30 cm is covered on the upper surface of the artificial wetland to adsorb ammonia nitrogen and provide a carrier for microorganism attachment.

[0037] As Figure 4 shown, the artificial wetland is an ecological system that uses the synergistic effect of plants, substrates, and microorganisms to purify water. The soil layer 33 of the planting area serves as a substrate, providing support for plant growth and also being a habitat for microorganisms. The water flow flows inside the soil, making full contact with the plant roots and microorganisms to achieve the removal of pollutants.

[0038] As Figure 4 shown, the biochar layer 35 has a developed pore structure and a large specific surface area, and can adsorb ammonia nitrogen in water. Ammonia nitrogen is a main pollutant in water bodies, and excessive ammonia nitrogen can lead to water eutrophication. The biochar layer 35 can not only adsorb ammonia nitrogen, but also serve as a carrier for microorganism attachment. Microorganisms form a biofilm on the surface of the biochar layer 35, which can degrade organic matter and other pollutants in water. The biochar layer 35 can improve the physical, chemical, and biological properties of the soil. It can improve the water and fertilizer retention capacity of the soil, improve soil aeration, and promote plant root growth. The plants in the artificial wetland can absorb nutrients in water, such as nitrogen, phosphorus, etc., thereby reducing pollutants in the water body.

[0039] As Figure 4 shown, moreover, the artificial wetland is an eco-friendly sewage treatment method that can protect the environment and improve the ecology. The artificial wetland has a certain landscape effect and can beautify the environment.

[0040] As Figure 4As shown in the figure, a biochar layer 35 is covered on the upper surface of the soil layer 33 in the planting area of the nitrification tank 31 to form an artificial wetland. By using the adsorption of the biochar layer 35, the degradation of microorganisms, and the absorption of plants, pollutants such as ammonia nitrogen in water can be effectively removed, the water quality can be improved, and the soil properties can be improved. It is an economical and effective ecological sewage treatment technology.

[0041] As Figure 4 shown in the figure, specifically, a shaping mesh layer is provided on the inner surface of the gravel layer, and a positioning ring 36 is provided inside the gravel layer and near the opening position of its own top. The bottom of the positioning ring 36 is connected to the top of the shaping mesh layer. The positioning ring 36 and the shaping mesh layer are used to position and maintain the shape of the gravel layer, avoid the instability of the gravel layer, and prevent the gravel layer from collapsing.

[0042] As Figure 4 shown in the figure, the shaping mesh layer and the positioning ring 36 are like the skeletons of the gravel layer, providing structural support. The shaping mesh layer covers the inner surface of the gravel layer, which can restrain the tendency of the gravel to move inward and prevent local collapse. The positioning ring 36 is located inside the gravel layer near the top and surrounds it for one week, further strengthening the gravel to prevent overall deformation and collapse. The shaping mesh layer and the positioning ring 36 can disperse the pressure received by the gravel layer to the entire structure, avoiding pressure concentration at a certain point and causing collapse. For example, when there is water flow or other heavy object pressure above, these pressures will be transmitted through the gravel to the mesh layer and the positioning ring 36, and then dispersed by them to the entire gravel layer structure.

[0043] As Figure 4 shown in the figure, there are gaps between the gravels, which are prone to sliding and rolling, especially under the impact of water flow or other external forces. The shaping mesh layer and the positioning ring 36 can limit the movement of the gravels, keep their relative positions stable, and thus maintain the overall shape and structure of the gravel layer.

[0044] As Figure 4 shown in the figure, further, a reinforcing sleeve ring 37 is provided inside the positioning ring 36. The bottom of the inside of the reinforcing sleeve ring 37 is provided with a cobweb-shaped combined sleeve 38. The cobweb-shaped combined sleeve 38 is evenly attached to the inner surface of the gravel layer, and the input end of the combined sleeve 38 is connected to the output end of the aeration system 32. The cobweb-shaped combined sleeve 38 is evenly distributed with air holes.

[0045] As Figure 4As shown, the aeration holes are evenly distributed on the spider-web combined sleeve 38, and can evenly release air bubbles into the gravel layer. These air bubbles dissolve in water, increasing the dissolved oxygen content in the water. Dissolved oxygen is necessary for the survival and activities of microorganisms and is crucial for aerobic biological treatment processes. Aeration not only provides oxygen but also promotes the "growth" of biofilms on the surface of gravel. Biofilms are adherent films composed of microorganisms that can adsorb and decompose organic pollutants in water. Sufficient oxygen can accelerate the formation and maturation of biofilms and improve their ability to degrade pollutants.

[0046] As Figure 4 shown, the spider-web structure ensures the even distribution of aeration holes in the gravel layer, avoiding the occurrence of aeration dead zones. Uniform aeration can ensure that the entire gravel layer is in a good oxidation environment and improve the treatment efficiency.

[0047] As Figure 4 shown, in addition, the reinforcement collar 37 and the spider-web combined sleeve 38 not only play the role of aeration but also can provide a certain support and reinforcement to the gravel layer, further improving the stability of the gravel layer. The combined sleeve 38 is arranged inside the reinforcement collar 37 and evenly fits on the inner surface of the gravel layer, which can hide the aeration equipment and make the entire gravel layer aesthetically pleasing.

[0048] As Figure 4 shown, generally speaking, the ingenuity of this advanced treatment unit 3 lies in coupling nitrification and denitrification together and forming an efficient nitrogen removal system through the participation of plants. The aeration system 32 ensures the oxygen required for nitrification, the soil layer 33 in the planting area provides the surface area required for the attachment and growth of microorganisms, and the plant roots further promote denitrification and nitrogen absorption. The pH adjustment tank 23 ensures that the nitrification reaction proceeds at an appropriate pH value. Through these synergistic effects, the ammonia nitrogen content in water can be effectively reduced. Example

[0049] As Figure 5 shown, the biological treatment unit 4 includes an ecological filter 41. Inside the ecological filter 41, several filter mesh rings 42 with uniformly changing cross-sections are coaxially arranged, and a mixed medium layer 43 is filled between adjacent filter mesh rings 42. The mixed medium layer 43 is composed of pine needle soil, granular soil, and sandy soil, and earthworms are arranged inside the mixed medium layer 43. The sewage flows through the vertical flow constructed wetland from top to bottom, and part of the pollutants are removed by the adsorption of plant roots and the decomposition of microorganisms. Then, the sewage enters the ecological filter 41, and the earthworms further purify the sewage by ingesting and digesting organic matter. At the same time, the activities of the earthworms can also loosen the soil and improve the water permeability of the filter. Finally, the treated water can be used for farmland irrigation or discharge.

[0050] The cross-section of the filter screen ring 42 shows a uniform gradual change in shape. The density of earthworms in the mixed medium layer 43 is 100 - 300 per square meter, and the diameter of the filter screen ring 42 gradually increases from top to bottom.

[0051] As Figure 5 shown, earthworms feed on organic matter in sewage and decompose it through digestion, reducing organic pollutants in the water. The activities of earthworms can loosen the soil, increase soil water permeability and aeration, which is beneficial to the growth of plant roots and the activities of microorganisms.

[0052] As Figure 5 shown, the excrement of earthworms is rich in nutrients and can be absorbed and utilized by plants. By regularly replacing the mixed medium layer 43, nutrient cycling is promoted. The activities of earthworms can improve soil structure, increase soil aggregates, and enhance the water and fertilizer retention capacity of the soil.

[0053] As Figure 5 shown, combining multiple biological purification technologies can more effectively remove pollutants such as organic matter, suspended solids, nitrogen, and phosphorus in sewage. Embodiment

[0054] A rural domestic sewage treatment method, based on the above rural domestic sewage treatment system, the treatment steps include: S1: Sewage feeding; Domestic sewage is discharged into the inside of the diversion trough 5 through the sewage system. Under the action of the axial flow pump 6, the sewage at a low position is lifted to the inside of the floating matter interception tank 21 at a high position.

[0055] S2: Sewage pretreatment; The grille set in the floating matter interception tank 21 is used to filter out floating matter in the sewage. The sewage after intercepting the floating matter enters the inside of the sedimentation tank 22. Through the sedimentation of the sedimentation tank 22, the supernatant generated after sedimentation is efficiently introduced into the subsequent pH adjustment tank 23 to achieve mud-water separation and obtain pretreated sewage.

[0056] S3: Advanced sewage treatment; The pretreated sewage enters the inside of the nitrification tank 31. Nitrification and denitrification are coupled together. Through the participation of plants, an efficient nitrogen removal system is formed; the aeration system 32 ensures the oxygen required for nitrification, the planting area soil layer 33 provides the surface area required for the attachment and growth of microorganisms, and the plant roots further promote denitrification and nitrogen absorption; the pH adjustment tank 23 ensures that the nitrification reaction proceeds at an appropriate pH value; through these synergistic effects, the ammonia nitrogen content in the water can be effectively reduced, and advanced treated sewage can be obtained.

[0057] S4: Sewage biological treatment; The deeply treated sewage enters the ecological filter tank 41. The earthworms further purify the sewage by ingesting and digesting organic matter. At the same time, the activities of the earthworms can also loosen the soil, improve the water permeability of the filter tank, and obtain the sewage after biological treatment.

[0058] S5: Sewage discharge; The sewage after biological treatment is centrally guided to the water collecting tank 7 through the bottom output end of the ecological filter tank 41, and the purified sewage is uniformly discharged through the water collecting tank 7.

[0059] The above are all the preferred embodiments of the present application, and the protection scope of the present application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A rural domestic sewage treatment system, characterized in that, It includes a concrete base frame (1), a diversion channel (5), a pretreatment unit (2), a deep treatment unit (3) and a biological treatment unit (4); the concrete base frame (1) is provided with three layers of concrete floor slabs (11) from top to bottom and is fixedly connected by concrete columns (12), the output end of the diversion channel (5) faces the input end of the pretreatment unit (2), the pretreatment unit (2) is arranged on the uppermost concrete floor slab (11), the deep treatment unit (3) is arranged on the middle concrete floor slab (11), the biological treatment unit (4) is arranged on the lowermost concrete floor slab (11), an axial flow pump (6) is integrated inside the diversion channel (5), the pretreatment unit (2) includes a floating matter interception tank (21), a sedimentation tank (22) and a pH adjustment tank (23) which are connected in sequence, the deep treatment unit (3) includes a nitrification tank (31) and an aeration system (32), and the biological treatment unit (4) includes an ecological filter tank (41).

2. The rural domestic sewage treatment system according to claim 1, characterized in that, A planting area is arranged on the inner wall of the nitrification tank (31), planting soil is filled in the planting area to form a planting area soil layer (33), and plants with developed root systems are planted in the planting area soil layer (33), and a permeable layer (34) is arranged on the inner wall of the planting area soil layer (33) of the nitrification tank (31).

3. The rural domestic sewage treatment system according to claim 2, characterized in that, The permeable layer (34) includes stone grains and activated carbon blocks, the diameter of the stone grains is larger than that of the activated carbon blocks, and an artificial wetland is formed at the top of the planting area.

4. The rural domestic sewage treatment system according to claim 3, characterized in that, The surface of the artificial wetland is covered with a biochar layer (35).

5. The rural domestic sewage treatment system according to claim 2, characterized in that, A shaped mesh surface layer is arranged on the inner ring of the permeable layer (34), a positioning ring (36) for fixing the shaped mesh surface layer is arranged at the top of the permeable layer (34), a reinforcing sleeve ring (37) is arranged on the inner ring of the positioning ring (36), and a cobweb-shaped combined sleeve (38) is arranged at the inner bottom of the reinforcing sleeve ring (37).

6. The rural domestic sewage treatment system according to claim 5, wherein, The cobweb-shaped combined sleeve (38) is connected with the aeration system (32), and air holes are evenly distributed on the surface of the combined sleeve (38).

7. The rural domestic sewage treatment system according to claim 1, characterized in that, A plurality of filter mesh rings (42) are coaxially arranged inside the ecological filter tank (41), a mixed medium layer (43) is filled between adjacent filter mesh rings (42), the mixed medium layer (43) includes mixed pine needle soil, granular soil and sandy soil, and earthworms are arranged in the mixed medium layer (43).

8. The rural domestic sewage treatment system according to claim 7, characterized in that, The cross section of the filter mesh ring (42) is in a stepped shape, the density of earthworms in the mixed medium layer (43) is 100 - 300 per square meter, and the diameter of the filter mesh ring (42) gradually increases from top to bottom.

9. The rural domestic sewage treatment system according to claim 7, characterized in that, The earthworms purify the sewage by ingesting the organic matter in the mixed medium layer (43), and the excrement generated by the activities of the earthworms and the mixed medium layer (43) form a cyclic regeneration structure.

10. A rural domestic sewage treatment method, based on the rural domestic sewage treatment system according to any one of claims 1-9, characterized in that: Its treatment steps include: S1: Sewage feeding; Domestic sewage is discharged into the inside of the diversion channel (5) through the sewage system, and under the action of the axial flow pump (6), the sewage at a low position is lifted to the inside of the floating matter interception tank (21) at a high position; S2: Sewage pretreatment; The grille set in the floating matter interception tank (21) is used to filter out the floating matter in the sewage. The sewage after intercepting the floating matter enters the inside of the sedimentation tank (22). Through the sedimentation of the sedimentation tank (22), the supernatant generated after sedimentation is efficiently introduced into the subsequent pH adjustment tank (23) to achieve the separation of mud and water, and obtain the pretreated sewage; S3: Advanced treatment of sewage; The pretreated sewage enters the inside of the nitrification tank (31). The nitrification and denitrification are coupled together. Through the participation of plants, a highly efficient nitrogen removal system is formed. The aeration system (32) ensures the oxygen required for nitrification. The planting area soil layer (33) provides the surface area required for the attachment and growth of microorganisms. The plant roots further promote denitrification and nitrogen absorption. The pH adjustment tank (23) ensures that the nitrification reaction proceeds at an appropriate pH value. Through these synergistic effects, the ammonia nitrogen content in the water can be effectively reduced, and the advanced treated sewage can be obtained; S4: Biological treatment of sewage; The advanced treated sewage enters the ecological filter (41). Earthworms further purify the sewage by ingesting and digesting organic matter. At the same time, the activities of earthworms can also loosen the soil, improve the water permeability of the filter, and obtain the biologically treated sewage; S5: Sewage discharge; The biologically treated sewage is centrally guided to the water collecting trough (7) provided at the bottom of the ecological filter (41) through the bottom output end of the ecological filter (41), and the purified sewage is uniformly discharged through the water collecting trough (7).

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