Tail water ecological wetland system for synergistically removing antibiotics and conventional pollutants

Abstract

The invention discloses a tail water ecological wetland system for synergistically removing antibiotics and conventional pollutants. The system comprises an ecological pond, a microbial fuel cell subsurface flow wetland, a photocatalytic plug flow type reaction tank and a surface flow wetland which are connected in sequence, a cathode layer, an anode layer and a matrix filler are arranged in the microbial fuel cell subsurface wetland; the microbial fuel cell subsurface wetland generates electric energy by decomposing pollutants in the tail water; a photocatalytic reaction plate and a light source are arranged in the photocatalytic plug-flow reaction tank, and a photocatalyst is arranged on the surface of the photocatalytic reaction plate; the light source is used for irradiating the photocatalytic reaction plate, and the light source is powered by electric energy generated by the microbial fuel cell subsurface flow wetland. A targeted removal unit, namely a photocatalytic reaction tank, is arranged for antibiotics, and is coupled with a microbial fuel cell, so that a conventional tail water wetland system is subjected to multifunctional design transformation, and the functions of efficiently removing the antibiotics and synergistically removing nitrogen and phosphorus are realized.

Description

Technical Field

[0001] The invention relates to the field of ecosystem restoration, and in particular to a tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants. Background Art

[0002] The direct discharge of tailwater into surface and groundwater bodies will still cause water deterioration, such as eutrophication. On the other hand, the emergence of antibiotics as a new type of pollutant in the natural water environment has attracted widespread attention. The large-scale use of antibiotics causes them to enter the environment through direct or indirect pathways, thereby causing environmental pollution and endangering the health of organisms. Since most antibiotics have poor biodegradability, the biological wastewater treatment process currently used by most sewage treatment plants cannot effectively remove antibiotics from sewage. Therefore, tailwater from sewage treatment plants is also one of the important sources of antibiotics in the natural water environment.

[0003] Most of the existing water treatment technologies for targeted removal of antibiotics are based on physical or chemical methods. Commonly used water antibiotic treatment processes include adsorption, membrane filtration, advanced oxidation and biological methods. Among them, the adsorption method has the possibility of secondary pollution, and the adsorption capacity is limited, and the adsorbent needs to be replaced regularly; the membrane in the membrane filtration method is easy to clog, and it needs to be cleaned and replaced regularly, which is costly; the advanced oxidation method is complex to operate, requires high concentrations of oxidants, and may have an impact on the environment.

[0004] As a biological treatment technology currently widely used in the deep treatment of tailwater from sewage plants, artificial wetlands have good removal effects on nitrogen, phosphorus, organic matter, etc. in tailwater. The biological method is environmentally friendly, has no secondary pollution, and has relatively low cost. However, as a biological method, the existing tailwater wetland technology has poor removal effect on antibiotics. In the process flow of tailwater wetlands, no targeted measures are set for the removal of antibiotics, which makes it difficult to degrade antibiotics with stable structures. The tailwater still has a high concentration after conventional artificial wetland treatment, which further leads to water environmental risks. Especially quinolone antibiotics, sulfonamide antibiotics, macrolide antibiotics, etc. The main reason is that these antibiotics are relatively stable in structure and difficult to remove through matrix and plant adsorption and microbial degradation. In addition, there are disadvantages such as unstable treatment effect of antibiotics in tailwater treated by artificial wetlands, which is greatly affected by seasons and hydrodynamic conditions.

[0005] Therefore, the existing technology lacks a technical solution that combines antibiotic treatment with tailwater wetland systems and uses artificial wetlands to treat antibiotics. How to combine efficient water antibiotic treatment technology with artificial wetland technology to achieve the synergistic removal of antibiotics and conventional pollutants (nitrogen, phosphorus, organic matter, etc.) in tailwater is one of the problems that need to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to provide a tailwater ecological wetland system constructed based on artificial wetland technology and antibiotic treatment technology to synergistically remove antibiotics and conventional pollutants in tailwater. The above purpose can be achieved by the following technical solution implementation:

[0007] A tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants, comprising an ecological pond, a microbial fuel cell subsurface wetland, a photocatalytic plug flow reaction pool, and a surface flow wetland connected in sequence;

[0008] The microbial fuel cell submerged flow wetland is provided with a cathode layer, an anode layer and a matrix filler; the microbial fuel cell submerged flow wetland generates electrical energy by decomposing pollutants in tail water;

[0009] The photocatalytic plug-flow reaction pool is provided with a photocatalytic reaction plate and a light source, the surface of the photocatalytic reaction plate is provided with a photocatalyst; the light source is used to irradiate the photocatalytic reaction plate, and the light source is powered by the electric energy generated by the microbial fuel cell submerged flow wetland.

[0010] Optionally, the ecological pond is 0.5 to 1.5 m deep, and a geotextile membrane anti-seepage layer is provided at the bottom of the ecological pond;

[0011] Optionally, the shore of the ecological pond is planted with emergent plants, including at least one of reeds, pampas grass, and water lily.

[0012] Optionally, an overflow weir is provided between the ecological pond and the microbial fuel cell submerged flow wetland.

[0013] Optionally, the microbial fuel cell submerged flow wetland adopts a vertical submerged flow wetland; the microbial fuel cell submerged flow wetland comprises a coarse filler layer, an anode layer, an intermediate filler layer, a fine filler layer, and a cathode layer arranged in sequence from bottom to top; a water inlet is provided at the bottom of one side of the microbial fuel cell submerged flow wetland, and a water outlet is provided at the top of the other side;

[0014] Optionally, the coarse filler layer uses gravel with a particle size of 30 mm to 40 mm; the middle filler layer uses ceramsite with a particle size of 3 mm to 6 mm; and the fine filler layer uses zeolite with a particle size of 1 mm to 2 mm and fine sand with a particle size of 0.35 mm to 0.5 mm.

[0015] Optionally, the anode layer and the cathode layer are both graphite electrode plates, and the anode layer and the cathode layer are connected to an external circuit via a copper core wire, and the external circuit is connected to a light source in a photocatalytic plug-flow reaction cell.

[0016] Optionally, emergent plants are provided above the cathode.

[0017] Optionally, the photocatalytic plug flow reaction pool adopts a multi-corridor design, and the reaction pool is divided into multiple corridors connected end to end in sequence by corridor partition walls, and 3-5 corridors are arranged; a plurality of photocatalytic reaction plates are arranged in the photocatalytic plug flow reaction pool along the water flow direction, and the photocatalytic reaction plates are fixed to the bottom of the photocatalytic plug flow reaction pool by columns and are tilted toward the sun.

[0018] Optionally, 2 to 3 photocatalytic reaction plates are arranged inside each corridor, and the photocatalytic reaction plates are 10 to 20 cm above the bottom of the pool and 10 to 15 cm above the water surface.

[0019] Optionally, the photocatalytic plug-flow reaction tank adopts submerged hole water inlet and overflow weir water outlet.

[0020] Optionally, the photocatalyst is a bismuth vanadate / activated carbon fiber composite material.

[0021] Optionally, the preparation method of the bismuth vanadate / activated carbon fiber composite material is: monoclinic BiVO 4 The solid powder is ultrasonically dispersed in water to obtain a dispersion; the dispersion is heated to 50-70°C, activated carbon fiber powder, BiVO 4 The mass ratio of the bismuth vanadate to the activated carbon fiber powder is 1:2 to 1:5; after sufficient stirring, solid-liquid separation is performed, and the separated solid phase is washed and dried to obtain a bismuth vanadate / activated carbon fiber composite material.

[0022] Optionally, the surface flow wetland is 0.5 to 1.5 m deep, and a geotextile membrane anti-seepage layer is provided at the bottom of the surface flow wetland; the bottom of the surface flow wetland is covered with 15 cm to 20 cm of planting soil; emergent plants are planted on the shore of the surface flow wetland, and submerged plants and floating leaf plants are planted in the surface flow wetland; aquatic animals are also placed in the surface flow wetland.

[0023] A tail water treatment method for synergistically removing antibiotics and conventional pollutants comprises the following steps:

[0024] Step 1) The tail water of the sewage treatment plant is connected from the front end of the ecological pond, and enters the microbial fuel cell subsurface wetland after being treated in the ecological pond;

[0025] Step 2) the microbial fuel cell submerged flow wetland generates electricity by decomposing pollutants in the tail water, and the tail water enters the photocatalytic plug flow reaction pool after being treated by the microbial fuel cell submerged flow wetland;

[0026] Step 3) the photocatalyst in the photocatalytic plug flow reaction tank degrades the antibiotics in the tail water under the irradiation of natural light and light source; wherein the light source is powered by a microbial fuel cell subsurface wetland; the tail water enters the surface flow wetland after being treated in the photocatalytic plug flow reaction tank;

[0027] Step 4) The tail water is discharged into natural water bodies after being treated in surface flow wetlands.

[0028] Optionally, in step 4), the tail water is discharged into a natural water body by gravity drainage after a hydraulic retention time of 7-9 days in a surface flow wetland.

[0029] The technical solution of the present invention has the following advantages:

[0030] The wetland system designed by the present invention sets a targeted removal unit for antibiotics in the tailwater wetland, namely, a photocatalytic reaction pool, and couples it with a microbial fuel cell, thereby carrying out a multifunctional design transformation on the conventional tailwater wetland system, and realizing the functions of efficient removal of antibiotics and synergistic removal of nitrogen and phosphorus. In the system, the subsurface wetland coupled with the microbial fuel cell not only promotes the degradation of pollutants, but also provides energy for the subsequent photocatalytic reaction; the photocatalytic reaction pool can degrade antibiotics that are difficult to degrade by microbial processes without secondary pollution. The two are combined with the ecological pond at the head of the system and the surface flow wetland at the tail, and the overall process realizes the synergy of electrocatalysis and photocatalysis, as well as the removal of pollutants and water purification processes in many aspects such as adsorption, filtration, biodegradation, and ecological stability. The whole system fully embodies the concept of green, low-energy consumption, ecological, and environmentally friendly tailwater wetlands. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is a diagram of the tailwater ecological wetland system for collaboratively removing antibiotics and conventional pollutants according to the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of a subsurface flow wetland for microbial fuel cells;

[0034] Figure 3 1. It is a schematic diagram of the structure of a photocatalytic plug-flow reaction cell;

[0035] Figure 4 yes Figure 3 Medium AA view;

[0036] Figure 5 yes Figure 3 Middle BB view;

[0037] Figure 6 Photocatalytic reaction plate and bracket structure diagram;

[0038] Figure 7 This is a structural diagram of a photocatalytic reaction plate. DETAILED DESCRIPTION

[0039] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0040] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "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; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0043] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0044] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0045] The present invention provides a tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants, comprising four treatment units connected in series:

[0046] (1) Ecological pond

[0047] Used for the pretreatment of tail water, it removes large suspended matter in the tail water through sedimentation, as well as SS and COD in conventional pollutants, and removes a portion of antibiotics adsorbed by suspended particles.

[0048] (2) Microbial fuel cell subsurface wetland

[0049] Microbial fuel cells are devices that use microorganisms to directly convert chemical energy in organic matter into electrical energy. Its basic working principle is: organic matter decomposes under the action of microorganisms and releases electrons and protons. Electrons rely on suitable electron transfer mediators to effectively transfer between biological components and anodes, and are transferred to cathodes through external circuits to form current. Compared with other existing technologies that use organic matter to generate energy, microbial fuel cells have operational and functional advantages: they directly convert substrates into electrical energy, ensuring high energy conversion efficiency. Unlike all existing bioenergy treatments, microbial fuel cells can operate effectively under normal temperature conditions; microbial fuel cells do not require waste gas treatment because the main component of the waste gas they produce is carbon dioxide, which does not have reusable energy under normal conditions. In local areas where there is a lack of power infrastructure, microbial fuel cells have the potential for widespread application, while also expanding the diversity of fuels used to meet our energy needs.

[0050] The microbial fuel cell subsurface wetland of the present invention efficiently removes conventional pollutants such as nitrogen, phosphorus, and organic matter in the tail water through the adsorption effect of subsurface wetland plants and the adsorption and filtration effect of matrix fillers, and cooperates with the effect of microbial fuel cells to remove antibiotics in the tail water to a certain extent. At the same time, the microbial fuel cell supplies power to the light source of the photocatalytic reaction in the next processing unit. The photocatalytic reaction is carried out under visible light conditions. Since the visible light conditions in the evening and night are very poor or non-existent, and the demand for photocatalysis still exists, a certain power supply is required.

[0051] The main body of the subsurface wetland includes, from bottom to top, a coarse filler layer (large-grained sand and gravel), an anode layer, an intermediate filler layer (ceramsite), a fine filler layer (small-grained zeolite / fine sand), a cathode layer, and emergent plants. Both the anode layer and the cathode layer are graphite electrode plates, which are connected to the external circuit through a copper core wire, and the external circuit is connected in series with the low-power LED lamp in the photocatalytic plug-flow reaction tank. A water inlet is provided at the bottom of one side of the wetland, and a water outlet is provided at the top of the other side.

[0052] (3) Photocatalytic plug flow reaction cell

[0053] The photocatalytic plug-flow reaction pool adopts a multi-corridor design, and the reaction pool is divided into a plurality of corridors connected end to end in sequence by corridor partition walls, and 3-5 corridors are arranged; a plurality of photocatalytic reaction plates are arranged in the photocatalytic plug-flow reaction pool along the water flow direction, and the photocatalytic reaction plates are fixed to the bottom of the photocatalytic plug-flow reaction pool by columns and are tilted toward the sun;

[0054] A supported bismuth vanadate material is arranged in the reaction tank, and various antibiotics in the tail water are degraded efficiently and pollution-free under visible light conditions through a photocatalytic reaction. Bismuth vanadate is a typical metal oxide, which has the characteristics of a wide light response range, low carbon, environmental protection, and non-toxicity, and is widely used in the fields of photocatalysis and electrocatalysis. The low-cost supported bismuth vanadate material used in the present invention is a bismuth vanadate / activated carbon fiber composite material.

[0055] Activated carbon fiber (ACF) is a new, efficient and multifunctional adsorption material. Activated carbon fiber has a large specific surface area (1000-3000m 2 / g) and abundant micropores, with the volume of micropores accounting for more than 90% of the total pore volume. Activated carbon fiber has a larger adsorption capacity and faster adsorption kinetics than granular activated carbon. It has high adsorption efficiency for organic matter and anions and cations in liquid and gas phases, fast adsorption and desorption speeds, and can be recycled. It is also resistant to acid, alkali, and high temperature, has strong adaptability, and has good electrical conductivity and chemical stability. It is an ideal environmentally friendly material. ACF products will not become loose or too tight when vibrated, and are particularly suitable for wastewater treatment and air purification with frequent adsorption and desorption.

[0056] Taking advantage of the rich pore structure and large specific surface area of ​​activated carbon fibers, antibiotics in water are adsorbed on the surface of activated carbon fibers, and then the loaded bismuth vanadate is used to photocatalytically degrade antibiotics under visible light irradiation conditions, achieving pollutant decomposition and restoration of activated carbon fiber adsorption performance, thereby achieving material recyclability. The loaded bismuth vanadate material in the reaction tank can adjust the inclination angle according to local light conditions to obtain the best light conditions.

[0057] In the present invention, a 40W LED lamp is installed on the wall of the reaction pool as a light source, and an LED point light source is installed at the wall corresponding to each bismuth vanadate / activated carbon fiber composite material. The LED point light source is installed in the form of an aluminum groove contour lamp, that is, the LED point light source is fixed and embedded in the aluminum groove with a buckle, and the aluminum groove is fixed to the wall of the reaction pool with screws. The microbial fuel cell and the external circuit are powered to provide a certain light source when the lighting conditions are poor.

[0058] (4) Surface flow wetland

[0059] As the last link of the system, it is used to further purify and stabilize the water quality. By planting aquatic plants such as submerged plants and emergent plants, a good water ecological environment and water ecosystem are created to enhance the self-purification capacity of the water body.

[0060] Example 1

[0061] like Figure 1 A tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants is shown, comprising:

[0062] Ecological Pond 1: A shallow pond in the form of an earthen pond is constructed, and the inlet water is the tailwater of the sewage treatment plant. The designed water depth is 0.5-1.5m, the slope ratio is 1:3-1:4, and reeds, cattails, and lilies are planted on the shore.

[0063] Microbial fuel cell subsurface flow wetland 2: A water distribution channel is set at the front end of the wetland to evenly distribute the incoming water to multiple groups of subsurface flow wetlands; Figure 2 As shown, the microbial fuel cell subsurface wetland 2 is laid from bottom to top: first, a coarse filler layer 21 of large-grained sandstone with a particle size of 30 mm to 40 mm is laid to ensure uniform layer thickness and a laying thickness of 0.5 m; a graphite electrode plate is laid on top of the coarse filler layer 21 as an anode layer 22 to ensure that the electrode plate is flat and undamaged and is reliably connected to the external circuit through a copper core wire; ceramsite with a particle size of 3 mm to 6 mm is laid on top of the anode layer 22 to form an intermediate filler layer 23 with a laying thickness of 0.3 m, the middle packing layer should be uniform and without gaps to facilitate water flow; small-particle zeolite or fine sand is laid on the middle packing layer to form a fine packing layer 24, with a laying thickness of 0.2m, and the fine packing layer 24 is also ensured to be uniform and without gaps; a graphite electrode plate is laid on the fine packing layer 24 as the cathode layer 25, and it is reliably connected to the external circuit; emergent plants are planted on the cathode layer 25, and plant varieties with strong adaptability and vigorous growth are selected to ensure the ecological function of the wetland, including reeds, water plantains, and calamus. An inlet is set at the lower part of one side of the wetland to ensure that the tail water can flow into the wetland evenly. An outlet is set at the top of the other side to ensure that the treated water can be discharged smoothly. The copper core wires of the anode layer and the cathode layer are connected to the external circuit, and the microbial fuel cell is debugged to ensure that it can work normally and provide power support for the photocatalytic reaction.

[0064] Photocatalytic plug flow reaction cell 3:

[0065] Reaction pool body: The plug-flow reaction pool adopts a multi-corridor design, with 3-5 corridors. The length of a single corridor is 20-50m, the aspect ratio is 5:1-10:1, the width-depth ratio is B / H=1-2, the longitudinal slope is 2%-3%, the pool wall is 0.2-0.5m high, and the designed water depth is 0.8m. The water is inletted by submerged holes and outlet by overflow weirs. The structure is reinforced concrete.

[0066] Preparation of activated carbon fiber (ACF): ACF was prepared by high temperature carbonization method.

[0067] The straw of emergent plants (such as reeds and spathiphyllum) can be taken from the ecological ponds and subsurface wetlands, surface wetlands or wetland peripheries of this wetland system. After washing the emergent plant straw with tap water, wash it three times with deionized water, dry it in a fume hood, and then place the dried straw in an oven at 105°C to constant weight, cool it to room temperature in a dryer, and crush it into powder with a grinder to 50-100 mesh, and put it into a wide-mouth bottle for later use.

[0068] Weigh 30g of straw powder into a beaker, add potassium carbonate solution with a concentration of about 1mol / L as an activator, stir and mix, and soak at room temperature for 8h. Place the impregnated sample in a porcelain crucible, cover it and place it in a muffle furnace for carbonization activation, increase the temperature by 150℃, and the interval time is 10min. When the temperature rises to 750℃, carbonize for 1h. When the temperature drops below 80℃, take out the sample, crush it to 160-200 mesh, and put it into a wide-mouth bottle for later use.

[0069] Preparation of supported bismuth vanadate materials: Preparation of BiVO by impregnation loading method 4 / ACF composite materials.

[0070] Take a certain amount of monoclinic BiVO 4 The solid powder is ultrasonically dispersed in deionized water, the dispersion is heated to 50-70°C, and the pre-prepared ACF is gradually added, with the mass ratio of BiVO4 to ACF being 1:2-1:5; a mechanical stirrer is used for sufficient stirring; then a solid-liquid separation operation is performed, and the separated solid matter is thoroughly washed and dried to obtain an activated carbon fiber-bismuth vanadate photocatalytic material with a specific size.

[0071] Material fixing and installation

[0072] like Figure 3-7 As shown, according to the site conditions, a frame (preferably a stainless steel frame) is used to place the prepared BiVO 4 / ACF photocatalytic material is fixed. That is, the photocatalytic material 311 is embedded in a frame 312 with a certain depth and an inner contour that fits the photocatalytic material, and the photocatalytic material is fixed on the outside of the frame 312 with a reinforcing wire 313 to form a photocatalytic reaction plate 32. A support 32 connected and fixed to the bottom of the pool is set at the bottom of the frame 312. 2 to 3 brackets are set inside each corridor inside the reaction pool, 10 to 20 cm above the bottom of the pool, 10 to 15 cm above the water surface, tilted to the south, and the inclination angle is determined according to the local lighting conditions of the wetland construction. According to the lighting conditions in most parts of my country, the design range is 20° to 45°.

[0073] illumination

[0074] A low-power LED lamp is used as a supplementary light source for the photocatalytic reaction, powered by a microbial fuel cell and an external circuit, and installed on the wall of the reaction pool.

[0075] Surface flow wetland 4: Construct a shallow pond in the form of an earth pond, with a designed water depth of 0.5 to 1m and a slope ratio of 1:3 to 1:4; cover the bottom of the pond with 15cm to 20cm of planting soil, and plant aquatic plants. Among them, emergent plants are planted in the shore area with a water depth of 0.3m to 0.5m, and the species are reeds, calamus, and cattail lights; submerged plants are planted in the area with a water depth of 0.5m to 1m, and the species are Vallisneria, Hydrilla verticillata, and Potamogeton serrata; floating leaf plants are dotted and planted in the wetland, and the species are lotus and water lily, and fixed with planting piles. In addition, fish, snails, shrimps, etc. are placed in the surface flow wetland to enhance the self-purification function of the wetland system. The surface flow wetland discharges water to natural water bodies.

[0076] Example 2

[0077] The tailwater of a sewage treatment plant mainly contains macrolide antibiotics such as erythromycin, roxithromycin, and azithromycin, as well as fluoroquinolone (chloramphenicol) and trimethoprim (sulfonamide) antibiotics. The contents of erythromycin, roxithromycin, azithromycin, fluoroquinolone, and trimethoprim are approximately 307.8 ng / L, 270.1 ng / L, 166.5 ng / L, 96.2 ng / L, and 51.9 ng / L, respectively. In addition, the concentrations of conventional pollutants in the water quality indicators are as follows: COD is 35 mg / L, TN is 8.7 mg / L, NH 3 -N is 2.8 mg / L, TP is 0.32 mg / L. The system in Example 1 is used for treatment, including the following steps:

[0078] Step 1) The tail water of the sewage treatment plant is connected from the front end of the ecological pond, and enters the microbial fuel cell subsurface wetland after being treated in the ecological pond;

[0079] Step 2) the microbial fuel cell submerged flow wetland generates electricity by decomposing pollutants in the tail water, and the tail water enters the photocatalytic plug flow reaction pool after being treated by the microbial fuel cell submerged flow wetland;

[0080] Step 3) the photocatalyst in the photocatalytic plug flow reaction tank degrades the antibiotics in the tail water under the irradiation of natural light and light source; wherein the light source is powered by a microbial fuel cell subsurface wetland; the tail water enters the surface flow wetland after being treated in the photocatalytic plug flow reaction tank;

[0081] Step 4) After the tail water has a hydraulic retention time of 7-9 days in the surface flow wetland, it is discharged into the natural water body by gravity drainage.

[0082] After the treatment, the contents of erythromycin, roxithromycin, azithromycin, fluoroquinolone, and trimethoprim in the effluent of the surface wetland were 65.5 ng / L, 43.6 ng / L, 45.9 ng / L, 44.2 ng / L, and 19.3 ng / L, respectively. That is, the removal rate of the system in Example 1 for the five types of antibiotics with the highest content in the tail water of a sewage plant ranged from 54.05% to 83.86%, with an average of 70.38%. In terms of conventional pollutants, COD, TN, and NH in the effluent of the surface wetland were 2.34 ng / L, 1.22 ng / L, and 1.3 ng / L, respectively. 3 The concentrations of -N and TP are 16mg / L, 3.2mg / L, 1.2mg / L, and 0.18mg / L, respectively, i.e. COD, TN, NH 3 The removal rates of -N and TP were 54.29%, 63.22%, 57.14% and 43.75% respectively, and the effluent met the Class IV water quality standards of the "Surface Water Environmental Quality Standards".

[0083] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants, characterized in that: It includes an ecological pond, a microbial fuel cell subsurface wetland, a photocatalytic plug flow reaction pool, and a surface flow wetland connected in sequence; The microbial fuel cell submerged flow wetland is provided with a cathode layer, an anode layer and a matrix filler; the microbial fuel cell submerged flow wetland generates electrical energy by decomposing pollutants in tail water; The photocatalytic plug-flow reaction pool is provided with a photocatalytic reaction plate and a light source, the surface of the photocatalytic reaction plate is provided with a photocatalyst; the light source is used to irradiate the photocatalytic reaction plate, and the light source is powered by the electric energy generated by the microbial fuel cell submerged flow wetland.

2. The tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants according to claim 1 is characterized in that: The ecological pond is 0.5 to 1.5 meters deep, and a geotextile membrane anti-seepage layer is provided at the bottom of the ecological pond; Preferably, the bank of the ecological pond is planted with emergent plants; Preferably, an overflow weir is provided between the ecological pond and the microbial fuel cell submerged flow wetland.

3. The tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants according to claim 1, characterized in that: The microbial fuel cell submerged flow wetland adopts a vertical submerged flow wetland; the microbial fuel cell submerged flow wetland comprises a coarse filler layer, an anode layer, an intermediate filler layer, a fine filler layer, and a cathode layer arranged in sequence from bottom to top; a water inlet is provided at the bottom of one side of the microbial fuel cell submerged flow wetland, and a water outlet is provided at the top of the other side; Preferably, the coarse filler layer uses gravel with a particle size of 30 mm to 40 mm; the middle filler layer uses ceramsite with a particle size of 3 mm to 6 mm; and the fine filler layer uses zeolite with a particle size of 1 mm to 2 mm and fine sand with a particle size of 0.35 mm to 0.5 mm.

4. The tailwater ecological wetland system for collaboratively removing antibiotics and conventional pollutants according to claim 3 is characterized in that: The anode layer and the cathode layer are both graphite electrode plates; the anode layer and the cathode layer are connected to an external circuit through a copper core wire, and the external circuit is connected to a light source in a photocatalytic plug-flow reaction tank.

5. The tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants according to claim 3 is characterized in that: Emergent plants are also planted above the cathode.

6. The tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants according to claim 1, characterized in that: The photocatalytic plug-flow reaction pool adopts a multi-corridor design, and the reaction pool is divided into a plurality of corridors connected end to end in sequence by corridor partition walls, and 3-5 corridors are arranged; a plurality of photocatalytic reaction plates are arranged in the photocatalytic plug-flow reaction pool along the water flow direction, and the photocatalytic reaction plates are fixed to the bottom of the photocatalytic plug-flow reaction pool by columns and are tilted toward the sun; Preferably, 2 to 3 photocatalytic reaction plates are arranged inside each corridor, and the lower edge of the photocatalytic reaction plate is 10 to 20 cm from the bottom of the pool and 10 to 15 cm from the water surface; Preferably, the photocatalytic plug-flow reaction tank adopts submerged hole water inlet and overflow weir water outlet.

7. The tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants according to claim 1, characterized in that: The photocatalyst is a bismuth vanadate / activated carbon fiber composite material; Preferably, the preparation method of the bismuth vanadate / activated carbon fiber composite material is: ultrasonically disperse the monoclinic BiVO4 solid powder in water to obtain a dispersion; heat the dispersion to 50-70°C, add activated carbon fiber powder, and the mass ratio of BiVO4 to activated carbon fiber powder is 1:2-1:5; after sufficient stirring, perform solid-liquid separation, wash and dry the separated solid phase, and obtain the bismuth vanadate / activated carbon fiber composite material.

8. The tailwater ecological wetland system for synergistically removing antibiotics and conventional pollutants according to claim 1, characterized in that: The surface flow wetland is 0.5 to 1.5 m deep, and a geotextile membrane anti-seepage layer is arranged at the bottom of the surface flow wetland; the bottom of the surface flow wetland is covered with 15 cm to 20 cm of planting soil; emergent plants are planted on the shore of the surface flow wetland, and submerged plants and floating leaf plants are planted in the surface flow wetland; aquatic animals are also placed in the surface flow wetland.

9. A tail water treatment method for synergistically removing antibiotics and conventional pollutants, characterized in that: The steps include: Step 1) The tail water of the sewage treatment plant is connected from the front end of the ecological pond, and enters the microbial fuel cell subsurface wetland after being treated in the ecological pond; Step 2) the microbial fuel cell submerged flow wetland generates electricity by decomposing pollutants in the tail water, and the tail water enters the photocatalytic plug flow reaction pool after being treated by the microbial fuel cell submerged flow wetland; Step 3) the photocatalyst in the photocatalytic plug-flow reaction tank degrades the tail water antibiotics under the irradiation of natural light and light source; The light source is powered by a microbial fuel cell subsurface wetland; the tail water is treated in a photocatalytic plug-flow reactor and then enters a surface wetland; Step 4) The tail water is discharged into natural water bodies after being treated in surface flow wetlands.

10. The tail water treatment method for collaboratively removing antibiotics and conventional pollutants according to claim 9, characterized in that: In the step 4), the tail water is discharged into the natural water body by gravity drainage after a hydraulic retention time of 7-9 days in the surface flow wetland.

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