Multi-level green ecological sewage treatment system

Abstract

The invention belongs to the technical field of sewage treatment, and discloses a multi-layer green ecological sewage treatment system which comprises an aeration vertical flow constructed wetland and at least one layer of horizontal subsurface flow constructed wetland which are vertically and stereoscopically arranged underground, the aeration vertical flow constructed wetland comprises a first fine gravel layer and at least two first wetland frame layers which are arranged from top to bottom, each first wetland frame layer is provided with a plurality of first wetland frames, first wetland filler is arranged in each first wetland frame, an aeration pipe is arranged at the bottom or below the first wetland frame layer at the bottommost layer, and a plurality of aerators are connected to the aeration pipe; the horizontal subsurface flow constructed wetland comprises a first water storage tank, a packed bed and a second water storage tank which are communicated in sequence; the packed bed comprises a second fine gravel layer and at least two second wetland frame layers which are arranged from top to bottom. According to the invention, the sewage can be effectively treated, the CODCr, ammonia nitrogen, TN, TP and SS of the treated water comprehensively reach the standard, and the water quality can reach the first-grade A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a multi-level green ecological sewage treatment system. Background Art

[0002] With the acceleration of the global industrialization process, sewage treatment has become an important issue for environmental protection and sustainable development. Existing sewage treatment technologies mainly include physical treatment, chemical treatment and biological treatment. Physical treatment methods such as sedimentation and filtration mainly remove suspended matter and some impurities in sewage, but the removal effect on dissolved organic matter and nutrients is limited. Chemical treatment methods such as oxidation, reduction, flocculation, etc. can effectively remove pollutants in sewage, but often require the addition of chemical agents, have high operating costs, and may cause secondary pollution. Biological treatment methods such as activated sludge method and biofilm method use the metabolism of microorganisms to degrade organic matter in sewage. They have the advantages of good treatment effect and low operating cost, but the removal efficiency of nutrients still needs to be improved, and they occupy a large area and have high requirements for environmental conditions. In recent years, artificial wetland treatment technology has been used as a new type of sewage treatment method. Artificial wetlands purify sewage by simulating the ecosystem of natural wetlands and using the synergistic effect of plants, substrates and microorganisms. Compared with traditional sewage treatment technologies, artificial wetlands have the advantages of low investment and operating costs, good treatment effects, and easy maintenance and management. At the same time, artificial wetlands can also effectively remove nutrients such as nitrogen and phosphorus in sewage, and have a certain ability to remove difficult-to-degrade organic matter and heavy metals. In addition, artificial wetlands can also be combined with traditional sewage treatment processes, such as the A2 / O process, to further improve the sewage treatment effect by adding artificial wetlands to deeply purify the effluent. Therefore, artificial wetland treatment technology has broad application prospects in the field of sewage treatment.

[0003] Constructed wetlands are different from natural wetlands. They are an ecological sewage treatment system that is artificially designed and transformed. Constructed wetlands are mainly composed of three parts: substrate, plants and microorganisms. The triple synergy achieved through the interaction of substrate, aquatic plants and microorganisms in the ecosystem achieves efficient treatment and aesthetically attractive green spaces and wildlife habitats. Low or zero power consumption and long-life constructed wetland systems are proven and sustainable to enhance the landscape. The removal mechanisms of artificial wetlands for sewage include sedimentation, filtration, biological and chemical effects, containment and plant absorption, which can reduce the content of soluble organic matter, suspended solids, ammonia, pathogens, hydrocarbons and metals. At present, constructed wetlands have gradually become the mainstream ecological wastewater treatment technology in the world.

[0004] Patent document CN117228817A discloses an automatically regenerable artificial wetland coupled with microbial electrochemistry, including a wetland frame and a solar power supply mechanism. The inner cavity of the wetland frame is installed with a partition plate, and the inner cavity of the wetland frame is divided into a first treatment chamber and a second treatment chamber by the partition plate. The artificial wetland effectively copes with impact loads through the coordinated use of the first module and the second module, and the use of microbial regeneration can enable the zeolite filler to efficiently and accurately control in-situ regeneration and reuse, and the wetland is easy to maintain. Patent document CN113149219A discloses a purification system for tail water of a sewage plant, including a water distribution well and an artificial wetland, an aeration device and a submersible sewage pump are arranged in the water distribution well, the output end of the submersible sewage pump is connected with a first water distribution pipe, the first water distribution pipe leads to the artificial wetland, a flower pipe is arranged at the bottom of the artificial wetland, the flower pipe is connected with the water collection well, the upper part of the water collection well is connected with an outlet pipe, a control valve is arranged on the outlet pipe, a water quality detection device is arranged at the front end of the control valve on the outlet pipe, a submersible pump is arranged in the water collection well, the output end of the submersible pump is connected with a second water distribution pipe, a nozzle is arranged above the artificial wetland, the nozzle is connected with the second water distribution pipe, and the control valve and the submersible pump are connected with the water quality detection device respectively. According to the above, it can be seen that the existing artificial wetland can effectively purify sewage, but the current artificial wetland has the problems of large area, heavy odor, easy clogging, and low sewage treatment efficiency in winter, and the high water quality requirements of the effluent have become the key restrictive factors restricting the development of artificial wetlands, and it is urgent to find effective technical measures to solve them thoroughly. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of large land occupation, strong odor, easy clogging and low sewage treatment efficiency in winter in the existing sewage treatment, and to provide a multi-level green ecological sewage treatment system.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A multi-level green ecological sewage treatment system, comprising an underground vertically arranged aerated vertical flow artificial wetland and at least one layer of horizontal subsurface flow artificial wetland;

[0008] The aerated vertical flow artificial wetland comprises a first fine gravel layer and at least two first wetland frame layers arranged from top to bottom, the first wetland frame layer is provided with a plurality of first wetland frames, the first wetland frames are provided with first wetland fillers, an aeration pipe is provided at the bottom or below of the first wetland frame layer at the bottom layer, a plurality of aerators are connected to the aeration pipe, and the air inlet of the aeration pipe is connected to the output pipe of the aeration fan;

[0009] The horizontal subsurface flow artificial wetland includes a first water storage tank, a filler bed, and a second water storage tank which are connected in sequence. The filler bed includes a second fine gravel layer and at least two second wetland frame layers arranged from top to bottom. The second wetland frame layer is provided with a plurality of second wetland frames. The second wetland frames are provided with second wetland fillers. A first planting layer is provided on the second fine gravel layer. The aerated vertical flow artificial wetland is connected to the horizontal subsurface flow artificial wetland through a first water pipe.

[0010] In the technical solution of the present invention, the sewage treatment system adopts an underground three-dimensional layered structure, that is, a multi-level arrangement is performed underground in a vertical direction to form a three-dimensional structure, including an artificial wetland layer formed by an aerated vertical flow artificial wetland and at least one artificial wetland layer formed by a horizontal subsurface flow artificial wetland, so as to obtain different water flow directions and treat sewage; aeration in the aerated vertical flow artificial wetland can provide sufficient dissolved oxygen, promote the growth and reproduction of aerobic microorganisms, and accelerate the decomposition of organic matter in the sewage to be treated; at the same time, in the structure of the aerated vertical flow artificial wetland, the sewage passes vertically downward from the surface through the first fine gravel layer and the first wetland filler, and the aerated vertical flow artificial wetland is used to treat the sewage. Gas is used to increase the oxygen supply so that the sewage can fully contact with the first wetland filler, increase the attachment area of ​​microorganisms, promote microbial metabolic activities, facilitate the adsorption and degradation of organic matter, and improve the removal efficiency of organic matter and nitrogen; the horizontal submerged flow artificial wetland allows the sewage to flow horizontally through the filler bed. This water flow pattern can make the sewage hydraulically retain longer in the filler bed, increase the contact time between microorganisms and sewage, and at the same time use the effects of microbial decomposition, plant absorption and filler adsorption to reduce the pollutant content in the sewage, which is beneficial to the denitrification of microorganisms (reducing nitrates to nitrogen gas), thereby removing nitrate nitrogen in the sewage.

[0011] Through the above technical scheme, the aerated vertical flow artificial wetland can effectively remove most of the organic matter in the sewage, and at the same time has a certain nitrification effect on ammonia nitrogen, providing a better water quality foundation for subsequent treatment. The horizontal subsurface flow artificial wetland has a better denitrification effect, and it also helps to further remove some organic matter and phosphorus in the sewage. In view of the problem that the existing artificial wetlands occupy a large area, the aerated vertical flow artificial wetland and the horizontal subsurface flow artificial wetland adopt a vertical stereoscopic setting to save land, with a burial depth of more than 3m. After treatment, the water can flow into the slope or ditch by gravity, and the earthwork excavation is not large, and the additional investment is not much. If the natural sunken pit is used, it will save the investment in earthwork and be more economical. At the same time, the treatment effect of traditional artificial wetlands is poor when the temperature is low in winter, and the artificial wetlands set up in the underground vertical stereoscopic setting have a heat preservation function, which can improve the treatment effect. At the same time, the underground vertical stereoscopic setting solves the problem of heavy odor, and the setting of different wetland fillers is not easy to cause blockage. The sewage treatment system set up in the underground vertical stereoscopic setting meets different sewage treatment needs through a combination of different levels, different water flow forms and treatment methods according to the sewage quality and effluent requirements.

[0012] As a preferred embodiment of the present invention, the first wetland filler and / or the second wetland filler is at least one of zeolite, shale, limestone, volcanic rock filter material, expanded clay, coal slag, blast furnace slag and activated carbon, and the porosity of the first wetland filler and / or the second wetland filler is controlled at 30% to 50%.

[0013] In the above technical solution, the multi-level green ecological sewage treatment system sets the horizontal subsurface flow artificial wetland at the bottom layer, the aerated vertical flow artificial wetland at the top layer, and the aerated vertical flow artificial wetland and at least one layer of horizontal subsurface flow artificial wetland are arranged in sequence from top to bottom. This design achieves efficient sewage treatment through the synergy of different levels, while taking into account eco-friendliness and odor control.

[0014] As a preferred embodiment of the present invention, the particle size of the first fine gravel layer ranges from 16 to 32 mm.

[0015] As a preferred embodiment of the present invention, the sewage treatment system comprises at least one layer of the horizontal submerged flow artificial wetland and the aerated vertical flow artificial wetland arranged from top to bottom.

[0016] As a preferred embodiment of the present invention, the sewage treatment system comprises the aerated vertical flow artificial wetland and at least one layer of the horizontal submerged flow artificial wetland arranged from top to bottom.

[0017] In the above technical scheme, when the environment has high requirements for odor emission, the multi-level green ecological sewage treatment system sets the aerated vertical flow artificial wetland at the bottom layer, and the horizontal subsurface flow artificial wetland is set above the aerated vertical flow artificial wetland. This is because a large amount of gas will be generated during the aeration process of the aerated vertical flow artificial wetland, which may contain odor components such as ammonia and hydrogen sulfide. Placing the aerated vertical flow at the bottom layer can effectively control these gases in the underground environment and reduce the possibility of direct emission into the atmosphere; the horizontal subsurface flow artificial wetland is placed in the upper layer, which can serve as a physical barrier and play a role of physical isolation, preventing the odor generated in the bottom layer from being directly emitted into the environment. At the same time, the fillers and plants in the horizontal subsurface flow can adsorb and absorb the odor, further reducing the odor concentration.

[0018] As a preferred embodiment of the present invention, the horizontal subsurface flow artificial wetland is provided with two layers, including a first horizontal subsurface flow artificial wetland and a second horizontal subsurface flow artificial wetland arranged from top to bottom, and the first horizontal subsurface flow artificial wetland and the second horizontal subsurface flow artificial wetland are connected by a second water pipe.

[0019] In the above technical scheme, the top layer of the multi-level green ecological sewage treatment system adopts an aerated vertical flow artificial wetland, the middle layer adopts a first horizontal subsurface flow artificial wetland, and the bottom layer adopts a second horizontal subsurface flow artificial wetland. After the sewage passes through the aerated vertical flow artificial wetland, the sewage will enter the first horizontal subsurface flow artificial wetland. By allowing the sewage to flow horizontally through the packing bed, the pollutant content in the sewage is further reduced by microbial decomposition, plant absorption and packing adsorption. The bottom layer adopts a second horizontal subsurface flow artificial wetland to further treat the sewage after the first two stages of treatment to ensure that the effluent water quality reaches a higher standard. Multi-level horizontal subsurface flow artificial wetlands can improve the removal efficiency of pollutants, especially in the removal of nutrients such as nitrogen and phosphorus.

[0020] As a more preferred embodiment of the present invention, the particle size range of the first wetland filler is 20-30 mm, the particle size range of the second wetland filler in the first horizontal submerged flow artificial wetland is 10-20 mm, and the particle size range of the second wetland filler in the second horizontal submerged flow artificial wetland is 5-15 mm.

[0021] As a preferred embodiment of the present invention, a water distribution pipe is arranged on the top or above of the aerated vertical flow artificial wetland for achieving uniform distribution of water into the aerated vertical flow artificial wetland, and a first water collection pipe is arranged on the bottom or below of the aerated vertical flow artificial wetland for collecting sewage treated by the aerated vertical flow artificial wetland.

[0022] As a preferred embodiment of the present invention, the first water pipe connecting the aerated vertical flow artificial wetland and the first horizontal submerged flow artificial wetland is a plurality of first drip pipes, and the first horizontal submerged flow artificial wetland and the second horizontal submerged flow artificial wetland are connected with a plurality of second drip pipes, and the first drip pipes and the second drip pipes are used to transport sewage downward.

[0023] In the above technical scheme, when the requirements for nitrogen removal and phosphorus removal are high, the sewage treatment system adopts a bottom-up arrangement of water flow. The direction of water flow can make the sewage flow upward from the lower layer, through the third-level horizontal undercurrent, the second-level horizontal undercurrent, and finally reach the first-level aerated vertical flow. This reverse flow can increase the contact time between the sewage and the treatment units on each layer, so that microorganisms and plants can more fully adsorb and decompose pollutants in the sewage. Advantages: It can further improve the effect of nitrogen removal and phosphorus removal, especially when treating high-concentration sewage, it can more effectively remove nitrogen and phosphorus from sewage. Water flow exchange: The water flow direction can be exchanged between units on each layer, for example, different water flow directions can be used at different stages, or reverse flow can be used in certain specific treatment units to increase the flexibility and treatment effect of the system.

[0024] As a preferred embodiment of the present invention, the number and diameter of the first dripping pipe or the second dripping pipe are calculated according to the following formula:

[0025]

[0026] Where Q is the total drainage flow of the drip pipe; n is the number of drip pipes; K is the roughness height of the drip pipe; α is the water filling rate; d is the diameter of the drip pipe.

[0027] As a preferred embodiment of the present invention, a pipeline horizontal submerged flow wetland is arranged in the sewage inlet pipe at the water inlet pipe end of the sewage treatment system, and the pipeline horizontal submerged flow wetland includes a third fine gravel layer and a third wetland frame layer arranged from top to bottom, the third wetland frame layer is provided with a plurality of third wetland frames, the third wetland frame is provided with a third wetland filler, and the third fine gravel layer is planted with third wetland plants.

[0028] In the above technical scheme, a pipeline horizontal submerged flow wetland is also arranged in the sewage inlet pipe at the water inlet end of the sewage treatment system. Since the underground pipeline is buried underground and the pipeline is generally long, the setting of the pipeline horizontal submerged flow wetland does not require land acquisition, which can save a lot of land and odor environmental pollution problems. At the same time, it can greatly increase the hydraulic retention time of sewage in the sewage treatment system, improve the water quality of wetland treatment, and reduce the land acquisition area of ​​subsequent artificial wetlands. When the pipeline horizontal submerged flow wetland is blocked and the filler needs to be replaced, it can be lifted out from the inspection port to further solve the blockage problem.

[0029] As a preferred embodiment of the present invention, the sewage treatment system is also provided with a circulation loop pipe for conveying the treated water to the starting link where the sewage enters the sewage treatment system to treat the water again, and a valve is provided on the circulation loop pipe.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention provides a multi-level green ecological sewage treatment system. The sewage treatment system is set up in multiple levels in the underground vertical direction, including an aerated vertical flow artificial wetland and at least one layer of horizontal subsurface flow artificial wetland. The aerated vertical flow artificial wetland can effectively remove most of the organic matter in the sewage, and has a certain nitrification effect on ammonia nitrogen, providing a better water quality basis for subsequent treatment. The horizontal subsurface flow artificial wetland has a better denitrification effect, and also helps to further remove some organic matter and phosphorus in the sewage. In view of the problem that the existing artificial wetlands occupy a large area, the aerated vertical flow artificial wetland and the horizontal subsurface flow artificial wetland are set up vertically and stereoscopically to save land. The burial depth is more than 3m. After treatment, the water can flow into the slope or ditch by gravity. The earthwork excavation is not large, and the investment is not much. If the natural sunken pit is used, the investment in earthwork will be saved, which is more economical. At the same time, the treatment effect of the traditional artificial wetland is poor when the temperature is low in winter, and the artificial wetland set up vertically and stereoscopically underground has a heat preservation function, which can improve the treatment effect. At the same time, the vertical stereoscopic setting underground solves the problem of heavy odor, and the setting of different wetland fillers is not easy to cause clogging problems. The underground vertical sewage treatment system meets different sewage treatment needs through a combination of different levels, using different water flow forms and treatment methods according to sewage quality and effluent requirements.

[0032] 2. The sewage treatment system provided by the present invention gradually reduces the concentration of pollutants in sewage through different levels of treatment units, and finally achieves the purpose of purifying water quality. Each level targets specific pollutants or treatment requirements, and realizes efficient sewage treatment through the comprehensive effects of physical, chemical and biological effects. This process is particularly suitable for rural domestic sewage treatment projects, and can effectively treat and purify sewage and reduce the impact on the environment.

[0033] 3. The sewage treatment system of the present invention can effectively treat sewage. The CODCr, ammonia nitrogen, TN, TP, SS and other contents of the treated water fully meet the standards, and the water quality can reach the Class A standard of the Pollutant Discharge Standard for Urban Sewage Treatment Plants (GB18918-2002). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the multi-level green ecological sewage treatment system in Example 2;

[0035] Figure 2 It is a structural schematic diagram of the multi-level green ecological sewage treatment system in Example 3;

[0036] Figure 3 This is a schematic diagram of the structure of the aerated vertical flow artificial wetland in Example 3;

[0037] Figure 4 This is a schematic diagram of the structure of the horizontal subsurface flow artificial wetland in Example 3;

[0038] Figure 5 This is a schematic diagram of the structure of the pipeline horizontal subsurface flow wetland in Example 5;

[0039] Markings in the figure: 1-sewage inlet pipe, 2-aerated vertical flow artificial wetland, 21-water distribution pipe, 22-first fine gravel layer, 23-first wetland frame, 24-first wetland filler, 25-aeration pipe, 26-first water collecting pipe, 27-first drip pipe, 3-horizontal subsurface flow artificial wetland, 31-first water storage tank, 32-second fine gravel layer, 33-second wetland frame, 34-second wetland filler, 35-second water storage tank, 36-second water pipe, 37-second drip pipe, 41-water outlet pipe, 42-circulation loop pipe, 43-system conversion pipe, 44-ventilation pipe, 51-third fine gravel layer, 52-third wetland frame, 53-third wetland filler, 54-sludge pit, 61-lighting device, 62-light guide device, 63-solar photovoltaic panel, 64-solar power storage device, 65-ventilation pavilion, 7-ground. DETAILED DESCRIPTION

[0040] In order to more clearly describe the invention purpose, technical scheme and technical effect advantages in the specific implementation case of the present invention, the scheme in the specific embodiment will be described in detail in combination with the drawings of the specification of the present invention. The specific technical scheme involved in the following specific embodiments is only for a clear and complete description of the innovative technical scheme of the present invention. It is only a part of the specific implementation scheme that can be adopted by the present invention, not all embodiments, and should not be understood as a limitation on the innovative scheme of the present invention. Any scheme adopting the same inventive concept of the present invention should be included in the protection scope of the present invention.

[0041] Secondly, the description of the drawings in the specific embodiments of the present invention is only for the convenience of technical personnel to understand the solution of the present invention. The partial details in the drawings are for the convenience of clearly presenting the technical solution. It should not be considered that all technical features in the drawings must be included in the specific implementation cases, and the detailed features in the drawings should not be identified as additional limitations on the innovative technical solution of the present invention. The components in the various embodiments described and shown in the drawings can be combined and arranged according to different configurations, and these changes in combination and arrangement should be identified as part of the entire embodiment of the innovative solution of the present invention and included in the scope of protection of the present invention.

[0042] It should be noted that, unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship, such as "up", "down", "left", "right", "center", "inside", "outside", etc., are all expressions based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the invented product / equipment / device is placed when it is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so that technicians can quickly understand the scheme, rather than indicating or implying that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0043] In addition, the use of terms such as "horizontal", "vertical", "overhanging", etc. does not mean that the corresponding device / component / element is absolutely horizontal, vertical or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element is set in a specific direction such as "horizontal", "vertical", "overhanging", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0044] In addition, the expressions “first”, “second”, “third”, etc. that appear in the terms are merely descriptions used to distinguish the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0045] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be 3, 4, 5, 6, 7, 8, 9, etc., or even more than 9.

[0046] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading and other commonly used connection means in the field. This connection can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two components.

[0047] Example 1

[0048] The present embodiment provides a multi-level green ecological sewage treatment system, including an aerated vertical flow artificial wetland 2 and at least one horizontal subsurface flow artificial wetland 3 arranged in a vertical three-dimensional manner underground; the aerated vertical flow artificial wetland 2 includes a first fine gravel layer 22 and at least two first wetland frame layers 23 arranged from top to bottom, the first wetland frame 23 layer is provided with a plurality of first wetland frames 23, the first wetland frame 23 is provided with a first wetland filler 24, the bottom or lower part of the first wetland frame 23 layer at the bottom is provided with an aeration pipe 25, and a plurality of aerators are connected to the aeration pipe 25, and an aeration pipe 25 is provided with a plurality of aerators. The air inlet of the air pipe 25 is connected to the output pipe of the aeration fan; the horizontal subsurface flow artificial wetland 3 includes a first water storage tank 31, a packing bed, and a second water storage tank 35 which are connected in sequence, the packing bed includes a second fine gravel layer 32 and at least two layers of second wetland frames 33 arranged from top to bottom, the second wetland frame 33 layer is provided with multiple second wetland frames 33, the second wetland frame 33 is provided with a second wetland filler 34, and a first planting layer is provided on the second fine gravel layer 32. The aerated vertical flow artificial wetland 2 and the horizontal subsurface flow artificial wetland 3 are connected by a first water pipe.

[0049] Different layers of wetland frames in the same vertical column are interconnected. Holes are opened below the upper wetland frames in the aerated vertical flow artificial wetland 2 or the horizontal subsurface flow artificial wetland 3. Through the hole design, sewage is transmitted from the upper wetland frames to the lower wetland frames in the form of water droplets. The function is to increase the contact with the air and increase the oxygen consumption of the water quality. Secondly, the hydraulic path is greatly shortened, the time is shortened, the water replenishment is more uniform, and the front-end blockage problem is alleviated.

[0050] The first wetland filler 24 and the second wetland filler 34 provide a surface for microorganisms to attach, have good adsorption and filtration properties, and promote the degradation and removal of pollutants in sewage. In some embodiments, the first wetland filler 24 and / or the second wetland filler 34 is at least one of zeolite, shale, limestone, volcanic rock filter material, expanded clay, coal slag, medical stone, blast furnace slag and activated carbon, and the porosity of the first wetland filler 24 and / or the second wetland filler 34 is controlled at 30% to 50%.

[0051] In this embodiment, the structure, material, and size of the first wetland frame 23 and the second wetland frame 33 may be the same or different. In this embodiment, the wetland frame is a cubic module box with an upper opening composed of a bottom plate and an outer frame plate. The frame is assembled with lightweight materials, and the bottom plate and the outer frame plate have evenly opened holes to facilitate water exchange between the inside and outside of the system.

[0052] In some embodiments, the sewage treatment system is further provided with a circulation loop pipe 42 for conveying the treated water to the starting point where the sewage enters the sewage treatment system to treat the water again. A valve is provided on the circulation loop pipe 42.

[0053] Example 2

[0054] This embodiment provides a multi-level green ecological sewage treatment system. The sewage treatment system is based on the embodiment 1. The sewage treatment system includes an aerated vertical flow artificial wetland 2 and at least one layer of horizontal subsurface flow artificial wetland 3 arranged from top to bottom. The horizontal subsurface flow artificial wetland 3 is arranged at the bottom layer, and the aerated vertical flow artificial wetland 2 is arranged at the top layer. Figure 1 , through the synergistic effect of different artificial wetland levels, efficient sewage treatment can be achieved while taking into account eco-friendliness and odor control.

[0055] Example 3

[0056] The present embodiment provides a multi-level green ecological sewage treatment system. The sewage treatment system is based on Embodiment 2, and the horizontal subsurface artificial wetland 3 is provided with two layers, including a first horizontal subsurface artificial wetland and a second horizontal subsurface artificial wetland arranged from top to bottom, and the first horizontal subsurface artificial wetland and the second horizontal subsurface artificial wetland are connected by a second water pipe 36. The ecological sewage treatment system adopts a three-layer three-dimensional upper and lower structure arrangement, which greatly increases the hydraulic gradient (the height difference between the inlet and outlet of each layer is large), the treatment efficiency is increased, and the blockage frequency is greatly alleviated. When more than three layers are used, more than 66% of the land can be greatly saved. At the same time, the burial depth is approximately equal to 4.5m, and the insulation function can improve the treatment effect. The internal treatment unit of each layer adopts a modular assembly type, which is convenient for replacement. The sewage treatment system in this embodiment is arranged underground, such as Figure 2 As shown, a ventilation booth 65 is provided next to it. The ventilation booth 65 is used for daily ventilation, personnel entrance and exit, and provides a passage for replacing fillers and plants. The ventilation booth 65 is provided with air inlets and air outlets for underground wind circulation. The first horizontal subsurface artificial wetland and the second horizontal subsurface artificial wetland are connected through a ventilation pipe 44, so that the wind circulates in the treatment system. In this embodiment, the wind circulates between the first horizontal subsurface artificial wetland and the second horizontal subsurface artificial wetland. If a circulation loop pipe 42 is provided, the circulation loop pipe 42 transports the water from the outlet pipe 41 to the aerated vertical flow artificial wetland 2, the starting link where the sewage enters the sewage treatment system.

[0057] The aeration fan inlet pipe required for aeration in the aerated vertical flow artificial wetland 2 uses the air (containing a large amount of oxygen) from the first horizontal subsurface flow artificial wetland on the second underground floor and the second horizontal subsurface flow artificial wetland on the third underground floor, so that the air is effectively recycled. The air on the second underground floor and the third underground floor is processed by the aerated vertical flow and horizontal subsurface flow, and contains a large amount of oxygen. This oxygen can be transported to the aeration system on the seventh floor of the ground through the air pump inlet pipe, further improving the aeration efficiency, while reducing the need for additional oxygen supply, thereby reducing energy consumption and operating costs.

[0058] The aerated vertical flow artificial wetland 2, the first horizontal subsurface flow artificial wetland, and the second horizontal subsurface flow artificial wetland are assembled structures, which are made of prefabricated concrete or steel structures. In this embodiment, the aerated vertical flow artificial wetland 2 or the horizontal subsurface flow artificial wetland 3 is formed by a 150mm concrete cushion layer, which provides stable support and bearing capacity to prevent the lower structure from being eroded by groundwater or soil; an impermeable geotextile is arranged on the concrete cushion layer at the bottom of the aerated vertical flow artificial wetland 2, and then a support plate is arranged to support the upper wetland frame and filler to ensure the stability and integrity of the structure. Figure 3 A water distribution pipe 21 is provided at the top or above the aerated vertical flow artificial wetland 2 to achieve uniform water distribution into the aerated vertical flow artificial wetland 2; the water distribution pipe 21 is connected to the sewage inlet pipe 1, and the water distribution pipe 21 is designed to be evenly distributed, usually in the form of a perforated pipe or a nozzle to achieve uniform water distribution. A first water collection pipe 26 is provided at the bottom or below the aerated vertical flow artificial wetland 2 to collect sewage treated by the aerated vertical flow artificial wetland 2. The water distribution pipe 21 and the first water collection pipe 26 use water supply hard polyvinyl chloride (PVC-U) pipes, the pipe pressure is not less than 0.8MPa, and the connection method is bonding. The first water collection pipe 26 (with small holes on it) is provided with non-woven fabric, which plays a filtering role, prevents impurities such as mud and sand from entering the water collection main pipe, affects the drainage effect, and keeps the drainage unobstructed. Non-woven fabric quality requirements: weight greater than or equal to 250g / m 2 ; Tensile strength: longitudinal greater than or equal to 30N / 5cm, transverse greater than or equal to 300N / 5cm; Vertical permeability coefficient: K>2.0×10 -4 / m / s. The non-woven fabric should be laid smoothly, with appropriate tightness, and should not be stretched too tight. The overlapping length should not be less than 300mm.

[0059] The first fine gravel layer 22 is used as the first filter layer to remove suspended solids and impurities in sewage. It has a thickness of 100 mm and is composed of fine gravel. The particle size of the fine gravel in the first fine gravel layer 22 ranges from 16 to 32 mm, and has good filtering performance. In some embodiments, a planting layer is provided on the first fine gravel layer 22, and wetland plants are present in the planting layer. The sewage treatment system is also provided with interconnected lighting devices 61 and light guide devices 62. The lighting device 61 includes sensors, microcomputers, drivers, micromotors, transmission systems, lens arrays, etc. The sensor provided on the ground 7 senses the sun's position, and the microcomputer issues instructions to drive the lens group to accurately track the sun, gather sunlight more than 10,000 times, and couple it into the optical fiber. The system automatically wakes up, tracks, and resets every day without human intervention. The light guide system includes indoor fixing or steering mechanisms for optical cables, projection lighting, etc., to achieve safety and aesthetic effects. The projection lighting is arranged on the top of the inner wall of the horizontal subsurface flow artificial wetland 3, and can illuminate the plants in the plant layer, provide sunlight for the plants to photosynthesize, and purify the air in the horizontal subsurface flow artificial wetland 3. The projection lighting can also be powered by the solar photovoltaic panel 63 on the ground 7, which converts light into electrical energy and stores it in the solar energy storage device 64, which can be used as a supplement at night or during the day when the light is not strong.

[0060] like Figure 4 As shown, the bottom of the horizontal subsurface flow artificial wetland 3 is a 150mm concrete cushion layer, and the wetland wrapping material on the concrete cushion layer is used to protect the internal structure of the wetland. The horizontal subsurface flow artificial wetland 3 includes a first water storage tank 31, a first filler bed, and a second water storage tank 35, which are horizontally connected in sequence. The thickness of the second fine gravel layer 32 is 100mm, and the particle size range of the fine gravel in the second fine gravel layer 32 is 10-25mm. A first planting layer is arranged on the second fine gravel layer 32, and there are wetland plants in the first planting layer. In this embodiment, the lower part of the second horizontal subsurface flow artificial wetland is the foundation, which is compacted by plain soil and then a concrete cushion layer is used.

[0061] The aerated vertical flow artificial wetland 2 and the horizontal subsurface flow artificial wetland 3 are connected by a first water pipe. In this embodiment, the first water pipe is a plurality of first drip pipes 27, and the plurality of first drip pipes 27 are evenly distributed between the aerated vertical flow artificial wetland 2 and the first horizontal subsurface flow artificial wetland.

[0062] In some embodiments, in addition to being connected by the second water pipe 36, the first horizontal subsurface flow artificial wetland and the second horizontal subsurface flow artificial wetland are also provided with a plurality of second drip pipes 37. In this embodiment, the plurality of second drip pipes 37 are vertically arranged between the first horizontal subsurface flow artificial wetland and the second horizontal subsurface flow artificial wetland. Figure 4As shown, the second drip pipe is provided so that the first horizontal subsurface artificial wetland can be treated by vertical water flow and horizontal flow, and the second horizontal subsurface artificial wetland is treated by horizontal flow. The provision of the first drip pipe 27 and the second drip pipe 37 enables each layer to be provided with a drip hole under each wetland frame to transport sewage downward, which greatly shortens the path, increases the oxygen content of sewage during the dripping process, and forms aerobic, anoxic, and anoxic echelons. In order to prevent the appearance of drip holes in the process of sewage dripping downward in the wetland frame, the wind speed can be controlled, and the water droplets will fall left and right under the influence of wind direction, thereby avoiding the appearance of drip holes. The second water storage tank 35 of the second horizontal subsurface artificial wetland is connected to the outlet pipe 41 to discharge the treated water.

[0063] The number of first or second drip pipes and the drip pipe diameter are calculated according to the following formula:

[0064]

[0065] Where Q is the total drainage flow of the drip pipe, in L / s; Q is the sum of the sewage inlet and circulating water; n is the number of drip pipes; K is the roughness height of the drip pipe, in m. When the drip pipe is a plastic pipe, K is 15*10 -6 m, when the drip pipe is a cast iron pipe, K is 25*10 -5 m; α is the water filling rate, when the drip pipe is a plastic pipe, α is 0.3, when the drip pipe is a cast iron pipe, α is 0.35; d is the diameter of the drip pipe, calculated as the inner diameter of the pipe, in m; to prevent clogging, the calculated diameter of the drip pipe needs to be greater than 5 times the clogging pollutant particles. For the convenience of calculation, the number of the first drip pipe is set to 10, the total drainage flow Q = 0.1L / s, and the drip pipe is a plastic pipe, so K = 15*10 -6 m, α=0.3, d=0.01m is calculated by the above formula, where the diameter of the blocking pollutant particles is less than 0.002m, which meets the conditions. Therefore, the first drip pipe is designed as 10 plastic pipes with a diameter of 0.01m, and the same method is used to design the second drip pipe.

[0066] The particle size of the first wetland filler 24 ranges from 20 to 30 mm, the particle size of the second wetland filler 34 in the first horizontal submerged flow artificial wetland ranges from 10 to 20 mm, and the particle size of the second wetland filler 34 in the second horizontal submerged flow artificial wetland ranges from 5 to 15 mm.

[0067] In some embodiments, the sewage treatment system is also provided with a system conversion pipe 43, one end of the system conversion pipe 43 is connected to the sewage inlet pipe 1, and the other end is connected to the horizontal submerged flow artificial wetland 3. A valve is provided on the system conversion pipe 43 for introducing the sewage in the sewage inlet pipe 1 into the horizontal submerged flow artificial wetland 3 to realize the conversion of different sewage treatment systems.

[0068] In some embodiments, when the requirements for nitrogen removal and phosphorus removal are high, the sewage treatment system adopts a bottom-up water flow arrangement. The water flow direction can make the sewage flow upward from the lower layer, passing through the third-level horizontal undercurrent, the second-level horizontal undercurrent, and finally reaching the first-level aerated vertical flow. This reverse flow can increase the contact time between the sewage and each layer of treatment units, so that microorganisms and plants can more fully adsorb and decompose pollutants in the sewage. Advantages: It can further improve the effect of nitrogen removal and phosphorus removal, especially when treating high-concentration sewage, it can more effectively remove nitrogen and phosphorus from sewage. Water flow exchange: The water flow direction can be exchanged between units at each layer, for example, different water flow directions can be used in different stages, or reverse flow can be used in certain specific treatment units to increase the flexibility and treatment effect of the system.

[0069] Sewage enters the sewage treatment system from the sewage inlet pipe 1, flows into the aerated vertical flow artificial wetland 2 from the water distribution pipe 21, flows out of the aerated vertical flow artificial wetland 2 from the first collecting pipe 26, enters the first horizontal submerged flow artificial wetland through the first drip pipe 27, or part of the sewage enters the first horizontal submerged flow artificial wetland from the system conversion pipe 43, and then is collected in the second water storage tank 35 after being treated in the first horizontal submerged flow artificial wetland, enters the first water storage tank 31 of the second horizontal submerged flow artificial wetland from the second water supply pipe 36, is collected in the second water storage tank 35 after being treated in the second horizontal submerged flow artificial wetland, and flows out from the outlet pipe 41.

[0070] The sewage treatment system of this embodiment adopts an aerated vertical flow artificial wetland 2 on the top layer, a first horizontal subsurface flow artificial wetland on the middle layer, and a second horizontal subsurface flow artificial wetland on the bottom layer. The results of the treated water after testing are shown in the table. From the data in the table, it can be seen that the CODCr, ammonia nitrogen, TN, TP, SS and other data of the treated water meet the standards, and the water quality can meet the Level A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB18918-2002). This shows that the sewage treatment system of the present invention can continuously remove organic matter and nitrogen and phosphorus, which can not only save investment and reduce operating costs, but also occupy less space, save energy and protect the environment, have high treatment efficiency, and be easy to replace, while ensuring the operating stability of the entire treatment system.

[0071] Table 1 Test results of sewage treatment system

[0072] project Water Intake Water Removal rate (%) CODCr(mg / L) 564 46 91.8 <![CDATA[NH3-N(mg / L)]]> 45 2.3 94.9 TN(mg / L) 48 4 91.7 TP(mg / L) 6 0.3 95.0 SS(mg / L) 264 10 96.2

[0073] Example 4

[0074] This embodiment provides a multi-level green ecological sewage treatment system. Based on the embodiment 1, the sewage treatment system includes at least one layer of horizontal subsurface flow artificial wetland 3 and aerated vertical flow artificial wetland 2 arranged from top to bottom.

[0075] When the environment has high requirements for odor emission, the multi-level green ecological sewage treatment system sets the aerated vertical flow artificial wetland 2 at the bottom layer, and the horizontal subsurface flow artificial wetland 3 is set above the aerated vertical flow artificial wetland 2. The aerated vertical flow artificial wetland 2 at the bottom layer can be easily connected to the odor collection system, and the generated odor is collected and treated through pipes, such as using biological filters, chemical absorption and other methods to further reduce odor emissions; the horizontal subsurface flow artificial wetland 3 is placed on the upper layer, which can serve as a physical barrier and play a role of physical isolation, blocking the odor generated at the bottom layer from being directly emitted into the environment. At the same time, the fillers and plants in the horizontal subsurface flow can adsorb and absorb the odor, further reducing the odor concentration. The horizontal subsurface flow on the ground layer 7 is usually planted with various aquatic plants, which have the ability to absorb and decompose odor components. For example, plants such as reeds and cattails can absorb odor substances such as ammonia and hydrogen sulfide through their roots and convert them into harmless substances, thereby purifying the air. This design can effectively avoid the problem of odor pollution.

[0076] Example 5

[0077] This embodiment provides a multi-level green ecological sewage treatment system. Based on the embodiment 1, the sewage treatment system has a horizontal subsurface wetland arranged in the sewage inlet pipe 1 at the water inlet end of the sewage treatment system. Figure 5 As shown, the pipeline horizontal subsurface flow wetland includes a third fine gravel layer 51 and a third wetland frame 52 layer arranged from top to bottom. The third wetland frame 52 layer is provided with multiple third wetland frames 52, and the third wetland frame 52 is provided with a third wetland filler 53. A second planting layer is arranged on the third fine gravel layer 51.

[0078] A pipeline horizontal submerged flow wetland is also arranged in the sewage inlet pipe 1 at the water inlet end of the sewage treatment system. Since the underground pipelines are buried underground and are generally long, the setting of the pipeline horizontal submerged flow wetland does not require land acquisition, which can save a lot of land and odor environmental pollution problems. At the same time, it can greatly increase the hydraulic retention time of sewage in the sewage treatment system, improve the water quality of wetland treatment, and reduce the land acquisition area of ​​subsequent artificial wetlands. When the pipeline horizontal submerged flow wetland is blocked and the filler needs to be replaced, it can be lifted out from the inspection port to further solve the blockage problem.

[0079] The water in the sewage inlet pipe 1 at the end of the water inlet pipe is pre-treated sewage, and the horizontal submerged wetland of the pipeline is set between the inspection wells. In this embodiment, a sewage drain pipe or drainage channel with a DN ≥ 500 mm is used in the starting inspection well, the middle inspection well, and the terminal inspection well, wherein a sludge pit 54 is set at the bottom of the sewage drain pipe or drainage channel, and the sewage drain pipe or drainage channel is inclined with a slope of 3%-5%, and the lower end faces the sludge pit 54, and the size of the sludge pit 54 is equal to a fixed frame). The generated sludge leads to the sludge pit 54, and the sludge is cleaned regularly, and the wetland frame can be fixed to prevent sliding. A third wetland frame 52 is arranged in the sewage drain pipe or on the drainage channel, and a pulley is arranged under the third wetland frame 52, and a horizontal track is arranged under the pulley. When the third wetland frame 52 is blocked and needs to be replaced, the third wetland frame 52 is moved and lifted out from the inspection wells on both sides for easy replacement. The structure, material, and size of the third wetland frame 52 and the first wetland frame 23 and the second wetland frame 33 can be the same or different.

[0080] In some embodiments, a fiber rope is arranged at the top of the horizontal subsurface wetland in the pipeline, and the central rope is made of nylon net or other materials. There is soft fiber filler on the fiber rope, and sewage microorganisms grow on the filler, forming a vertically integrated pollutant removal system of fiber filler contact oxidation, plants, light filler filtration, and bottom mud discharge.

[0081] For those skilled in the art, when understanding the solutions described in the specific embodiments of the present invention, they can refer to the conventional technical manuals in the field. At the same time, for the places where the above-mentioned terms appear, they can make appropriate understandings or adjustments for reference, and deduce the implementation of the same or similar technical solutions without paying any creative work.

[0082] The above embodiments describe only the basic principles, main features and / or advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and the invention content of the specification only describe the principles or specific cases of the present invention. Without departing from the essence of the innovative idea of ​​the present invention, the innovative scheme of the present invention may be subject to various changes and improvements, and these changes and improvements all fall within the scope of protection required by the present invention.

Claims

1. A multi-level green ecological sewage treatment system, characterized in that: It includes an underground vertically-arranged aerated vertical flow artificial wetland (2) and at least one layer of horizontal subsurface flow artificial wetland (3); The aerated vertical flow artificial wetland (2) comprises a first fine gravel layer (22) and at least two first wetland frame layers arranged from top to bottom, wherein the first wetland frame layer is provided with a plurality of first wetland frames (23), wherein the first wetland frames (23) are provided with first wetland fillers (24), and an aeration pipe (25) is provided at the bottom or below of the first wetland frame layer at the bottom layer, and a plurality of aerators are connected to the aeration pipe (25); The horizontal subsurface flow artificial wetland (3) comprises a first water storage tank (31), a filler bed, and a second water storage tank (35) which are connected in sequence; the filler bed comprises a second fine gravel layer (32) and at least two second wetland frame layers arranged from top to bottom; the second wetland frame layer is provided with a plurality of second wetland frames (33); a second wetland filler (34) is arranged in the second wetland frame (33); a first planting layer is arranged on the second fine gravel layer (32); and the aerated vertical flow artificial wetland (2) and the horizontal subsurface flow artificial wetland (3) are connected via a first water pipe.

2. A multi-level green ecological sewage treatment system according to claim 1, characterized in that: The first wetland filler (24) and / or the second wetland filler (34) is at least one of zeolite, shale, limestone, volcanic rock filter material, ceramsite, coal slag, blast furnace slag and activated carbon, and the porosity of the first wetland filler (24) and / or the second wetland filler (34) is 30% to 50%.

3. A multi-level green ecological sewage treatment system according to claim 1, characterized in that: The sewage treatment system comprises at least one layer of the horizontal submerged flow artificial wetland (3) and the aerated vertical flow artificial wetland (2) arranged from top to bottom.

4. A multi-level green ecological sewage treatment system according to claim 1, characterized in that: The sewage treatment system comprises the aerated vertical flow artificial wetland (2) and at least one layer of the horizontal submerged flow artificial wetland (3) arranged from top to bottom.

5. A multi-level green ecological sewage treatment system according to claim 4, characterized in that: The horizontal subsurface flow artificial wetland (3) is provided with two layers, including a first horizontal subsurface flow artificial wetland and a second horizontal subsurface flow artificial wetland arranged from top to bottom, and the first horizontal subsurface flow artificial wetland and the second horizontal subsurface flow artificial wetland are connected via a second water pipe (36).

6. A multi-level green ecological sewage treatment system according to claim 5, characterized in that: The particle size of the first wetland filler (24) is in the range of 20 to 30 mm, the particle size of the second wetland filler (34) in the first horizontal submerged flow artificial wetland is in the range of 10 to 20 mm, and the particle size of the second wetland filler (34) in the second horizontal submerged flow artificial wetland is in the range of 5 to 15 mm.

7. A multi-level green ecological sewage treatment system according to claim 5, characterized in that: The first water pipe connecting the aerated vertical flow artificial wetland (2) and the first horizontal submerged flow artificial wetland is a plurality of first drip pipes (27), and the first horizontal submerged flow artificial wetland and the second horizontal submerged flow artificial wetland are connected by a plurality of second drip pipes (37), and the first drip pipes (27) and the second drip pipes (37) are used to transport sewage downward.

8. A multi-level green ecological sewage treatment system according to claim 7, characterized in that: The number of the first dripping pipes (27) or the second dripping pipes (37) and the dripping pipe diameters are calculated according to the following formula: Where Q is the total drainage flow of the drip pipe; n is the number of drip pipes; K is the roughness height of the drip pipe; α is the water filling rate; d is the diameter of the drip pipe.

9. A multi-level green ecological sewage treatment system according to any one of claims 1 to 8, characterized in that: A pipeline horizontal submerged flow wetland is arranged in the sewage inlet pipe (1) of the sewage treatment system. The pipeline horizontal submerged flow wetland comprises a third fine gravel layer (51) and a third wetland frame layer arranged from top to bottom. The third wetland frame layer is provided with a plurality of third wetland frames (52). A third wetland filler (53) is arranged in the third wetland frame (52). Third wetland plants are planted on the third fine gravel layer (51).

10. A multi-level green ecological sewage treatment system according to any one of claims 1 to 8, characterized in that: The sewage treatment system is also provided with a circulation loop pipe (42) for conveying treated water to the starting point where sewage enters the sewage treatment system, and a valve is provided on the circulation loop pipe (42).

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