Flexible functionalized fillers, modular constructed wetlands and their methods for purifying typical rural domestic sewage

Abstract

Flexible functionalized packing materials, modular constructed wetlands, and their methods for purifying typical rural domestic sewage belong to the field of rural domestic sewage treatment technology. The flexible functionalized packing materials are obtained by wrapping functionalized packing materials with a metal-woven flexible fiber wrapping material. The functionalized packing materials include solid packing materials and embedded microorganisms. The solid packing materials (volcanic rock with a porosity between 40% and 50%) embed microorganisms in their porous structure. The flexible functionalized packing materials are placed on a rigid support structure to form an integral flexible functionalized packing material module. The flexible functionalized packing material module includes three types of functional wetland modules: aerobic respiration enhanced ammonia nitrogen oxidation wetland module, facultative denitrification wetland module, and enhanced phosphorus removal wetland module. The module consists of three parts: internally embedded functionalized microbial packing materials, a flexible metal-woven flexible fiber wrapping material, and a rigid supporting carbon steel skeleton. In this invention, the functionalized packing materials embed functional microorganisms on the basis of the original packing materials. By fixing the microorganisms, the number of microorganisms in the packing materials is increased, improving the efficiency of pollutant removal. Using functional bacteria to replace traditional miscellaneous bacteria allows for precise control of the packing material's function, and the arrangement can be adjusted according to the quality of the domestic sewage.

Description

Technical Field

[0001] This invention belongs to the field of rural domestic sewage treatment technology, specifically relating to a flexible functionalized filler, a flexible modular constructed wetland, and a method for purifying rural domestic sewage using the substrate. Background Technology

[0002] The state has set new goals and requirements for rural domestic sewage treatment, demanding a treatment rate of over 40%. Therefore, practical and feasible rural domestic sewage treatment technologies are crucial for achieving this goal. Rural domestic sewage is characterized by: low COD (100-150 mg / L), and high ammonia nitrogen (generally 70-110 mg / L, especially pronounced in winter). Traditional activated sludge processes for this type of sewage suffer from low organic carbon sources and unstable operation, particularly poor performance in winter. To address this issue, flexible modular constructed wetlands and their purification methods for typical rural domestic sewage have been proposed.

[0003] Traditional constructed wetland purification mechanisms utilize a complex ecosystem of wetland substrates, microorganisms, and plants to address organic pollutants, ammonia nitrogen, and total phosphorus (TP) in wastewater through physical, chemical, and biological processes. Pollution purification is achieved through wetland substrate filtration and adsorption, wetland plant absorption and decomposition, and wetland microbial absorption and metabolism. However, traditional constructed wetlands have poor purification capabilities for rural domestic sewage with high ammonia nitrogen levels, are prone to clogging, and can even damage the wetland ecosystem due to low winter temperatures and excessively high ammonia nitrogen concentrations, leading to a complete loss of purification function. Therefore, enhancement and optimization are necessary to ensure the stable application of constructed wetland technology in rural domestic sewage treatment projects. This invention proposes a modular constructed wetland for typical rural domestic sewage and its purification method. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of easy clogging and poor operation of traditional constructed wetlands for domestic sewage with high ammonia nitrogen concentration. It proposes flexible functional filler, modular constructed wetlands and a method for purifying rural domestic sewage using this technology. This invention adopts flexible functional filler modules as wetland substrate, and multiple functional filler modules are combined to form a modular constructed wetland. The wetland is divided into three types of areas according to the functional classification of different functional areas: aerobic respiration enhanced ammonia nitrogen oxidation wetland module; facultative denitrification wetland module; enhanced phosphorus removal wetland module; these three modules are respectively arranged at the sewage inlet, the middle section of sewage treatment and the sewage outlet; (1) due to the low COD and high ammonia nitrogen of the influent, the residence time of the aerobic wetland is shortened (to 8 hours), the dissolved oxygen concentration is increased and ammonia oxidation is enhanced; (1) The residence time in the facultative anaerobic zone is increased to 12 hours, effectively removing nitrogen; the residence time in the dephosphorization zone is increased to 2 hours by adopting innovative dephosphorization technology; (2) A flexible modular matrix with structural support is adopted. Due to the combination of rigid support (carbon steel skeleton) and flexible matrix, the hydraulic flow pattern in the wetland is innovated: the horizontal flow between modules and the vertical flow through the matrix are combined, which effectively promotes mass transfer and diffusion, especially the mass transfer and diffusion of dissolved oxygen, which is beneficial to ammonia oxidation; (3) In the aerobic wetland area, perforated pipes are used to enhance atmospheric dissolved oxygen in combination with reed wetland plants, which increases the dissolved oxygen concentration in the aerobic wetland area to 2-3 mg / l. (4) The performance of the modular artificial wetland can be guaranteed by building an artificial greenhouse when the outside temperature is low in winter, and the artificial wetland device can be guaranteed to operate stably under different outside temperature conditions.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The flexible functionalized filler is obtained by wrapping functionalized filler with a metal-woven flexible fiber wrapping material; the functionalized filler includes solid filler and embedded microorganisms; the solid filler (volcanic rock, with a porosity between 40% and 50%) embeds microorganisms in its porous structure. The flexible functionalized filler is placed on a rigid support structure to form an integral flexible functionalized filler module.

[0007] Modular constructed wetlands consist of wetland substrate and constructed wetland structure, wherein:

[0008] The flexible functionalized packing module includes three types of functional aerobic respiration enhanced ammonia nitrogen oxidation wetland module, facultative denitrification wetland module, and enhanced phosphorus removal wetland module; the module consists of three parts: internally embedded functionalized microbial packing, flexible metal woven flexible fiber wrapping material, and rigid supporting carbon steel skeleton.

[0009] The aforementioned metal-woven flexible fiber wrapping material is prepared through a weaving process, using three types of metal fibers: 25μm 316L stainless steel wire, 12μm TiO2 nanowires, and 8μm carbon fiber wires. These fibers are woven in a two-up-one-down twill weave to form a mesh-like spherical wrapping material, allowing domestic sewage to flow in and out. It serves four functions: 1. Pre-screening of larger solid particles in the water; 2. The carbon fiber wires and TiO2 nanowires can form localized micro-electrolysis, achieving denitrification through micro-electrolysis oxidation-reduction; 3. Wrapping the internal functionalized filler to form flexible functional modules, facilitating overall installation, disassembly, and cleaning; 4. The combination of rigid support (carbon steel skeleton) and flexible substrate innovates the hydraulic flow pattern within the wetland: the combination of horizontal flow between modules and vertical flow through the substrate effectively promotes mass transfer and diffusion, especially dissolved oxygen, which is beneficial for ammonia oxidation; 5. The metal mesh structure can intercept the internal functionalized filler to prevent loss and clogging.

[0010] The TiO2 nanowires and carbon fiber wires in the metal fiber-encapsulated material form anode and cathode micro-electrolysis, which purifies carbon and nitrogen pollutants in domestic sewage through oxidation-reduction reactions.

[0011] The aerobic respiration enhanced ammonia nitrogen oxidation wetland module includes natural volcanic rock embedded with nitrifying bacteria, internal air pipes and wrapping material, which enhances ammonia nitrogen oxidation by embedding nitrifying bacteria in the pores of the packing material and by using the air pipes.

[0012] The facultative nitrification wetland module includes natural volcanic rock for embedding denitrifying bacteria, internal air pipes, and wrapping material. By embedding nitrifying bacteria in the pores of the packing material and passing them through the air pipes, the denitrification process is enhanced to achieve nitrogen removal.

[0013] The enhanced phosphorus removal wetland module packing material includes a mixture of natural volcanic rock and limestone. The pores of the packing material encapsulate facultative anaerobic denitrifying polyphosphate bacteria. These bacteria can utilize oxygen and nitrate as electron acceptors and can absorb large amounts of dissolved orthophosphate from wastewater, synthesizing polyphosphates within their cells. The phosphorus accumulation by polyphosphate bacteria far exceeds the amount of phosphorus required for normal microbial growth, reaching 6% to 8% of the cell weight. By employing the biological enhanced phosphorus removal method with encapsulated polyphosphate bacteria, both phosphorus removal and nitrate removal can be enhanced.

[0014] The multifunctional flexible functional module includes three types of functional wetland modules: aerobic respiration enhanced ammonia nitrogen oxidation wetland module, facultative denitrification wetland module, and enhanced phosphorus removal wetland module, which are respectively arranged at the sewage inlet, the intermediate section of sewage treatment, and the sewage outlet; thus forming a functional classification for different functional areas.

[0015] The modular constructed wetland device uses multifunctional flexible functional modules to perform in-depth treatment of rural domestic sewage by functionally dividing the sewage into zones according to the characteristics of typical rural domestic sewage.

[0016] A method for deep purification of rural domestic sewage using the aforementioned modular constructed wetland includes the following steps:

[0017] Step 1: The embedded functionalized filler is loaded into the metal woven flexible fiber wrapping material to form a flexible functionalized module with enhanced ammonia nitrogen oxidation, denitrification and enhanced phosphorus removal;

[0018] Step 2: The aerobic respiration enhanced ammonia nitrogen oxidation wetland module, the facultative denitrification wetland module, and the enhanced phosphorus removal wetland module are respectively arranged at the sewage inlet, the intermediate section of the sewage treatment, and the sewage outlet to form functional artificial wetlands with different functional areas.

[0019] Step 3: Domestic sewage flows through a modular constructed wetland, achieving deep purification. The rigid support (carbon steel frame) combined with a flexible substrate creates an innovative hydraulic flow pattern within the wetland: the combination of horizontal flow between modules and vertical flow through the substrate effectively promotes mass transfer and diffusion, especially dissolved oxygen, which is beneficial for ammonia oxidation. Functional fillers can remove carbon and nitrogen pollutants from the water. The external metal-woven flexible wrapping material can intercept suspended large inorganic particles in the sewage, prevent the loss of internal fillers, reduce the risk of device blockage, minimize microbial loss, and improve removal efficiency.

[0020] Step 4: In the adjustment and subsequent maintenance of the entire constructed wetland, this flexible functional modular structure, because it is wrapped with metal woven flexible fiber wrapping material, can be completely removed and replaced or thoroughly cleaned, and can be arbitrarily combined according to the corresponding water quality requirements.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. This invention improves the filler material in constructed wetlands by replacing it with a detachable, flexible, functional filler module. This module has the advantage of being able to be combined according to the quality of domestic sewage to meet water purification requirements.

[0023] 2. Innovative fluidity: The flexible functional packing module combines rigid support (carbon steel frame) with flexible matrix, creating an innovative hydraulic flow pattern in wetlands. The combination of horizontal flow between modules and vertical flow through the matrix effectively promotes mass transfer and diffusion, especially dissolved oxygen, which is beneficial for ammonia oxidation.

[0024] 3. The functionalized packing material in this invention embeds functional microorganisms into the original packing material. By fixing these microorganisms, the number of microorganisms in the packing material is increased, thereby improving the efficiency of pollutant removal. Replacing traditional mixed bacteria with functional bacteria allows for precise control of the packing material's function, enabling appropriate adjustments based on the quality of domestic sewage.

[0025] 4. The exterior is wrapped with a metal woven flexible fiber wrapping material. This new metal woven flexible fiber wrapping material has the characteristics of strong corrosion resistance and good toughness, which allows the flexible functional module to be filled and arranged arbitrarily, and can be removed for cleaning when needed without damaging or leaking the functional filler, avoiding the loss of particulate filler and preventing blockage.

[0026] 5. The flexible functionalized filler module can be disassembled and arranged arbitrarily, can be removed for thorough cleaning, and can be recycled and reused. It only requires one processing, which reduces subsequent maintenance costs and has high economic benefits. Attached Figure Description

[0027] Figure 1 Diagram of a modular constructed wetland device;

[0028] Figure 1 In the middle, 1: Insulated greenhouse, 2: Flexible functional filler module, 3: Wetland plants, 4: Perforated pipe.

[0029] Figure 2 A diagram showing the location distribution of three different functional modules;

[0030] Figure 2 In the middle, 5: aerobic respiration enhanced ammonia nitrogen oxidation wetland module, 6: facultative anaerobic denitrification wetland module, 7: enhanced phosphorus removal wetland module.

[0031] Figure 3 for Figure 1 Detailed structural diagram of the perforated tube;

[0032] Figure 4 Diagram of flexible functionalized filler module;

[0033] Figure 4 In the middle, 2-1: metal braided flexible fiber wrapping material, 2-2: functionalized filler, 2-3: rigid support structure, 2-1-1: carbon fiber filament, 2-1-2: TiO2 filament, 2-1-3: 316L stainless steel filament, 2-2-1: solid filler; 2-2-2: embedded microorganism. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0035] This invention provides a modular constructed wetland device, such as Figures 1-3 As shown, the flexible functional module is as follows Figure 4 As shown, it includes a metal-woven flexible fiber wrapping material 2-1, a functionalized filler 2-2, and a rigid support structure 2-3, wherein:

[0036] The modular constructed wetland adjusts the hydraulic retention time through the volume ratio of its three functional zones. The ratio of aerobic respiration enhanced ammonia nitrogen oxidation wetland module 5: facultative denitrification wetland module 6: enhanced phosphorus removal wetland module 7 is 4:6:1, achieving a wastewater treatment time of 8h:12h:2h. The length ratio of aerobic respiration enhanced ammonia nitrogen oxidation wetland module 5, facultative denitrification wetland module 6, and enhanced phosphorus removal wetland module 7 is 2:4:1, the width ratio is 1:1:1, and the height ratio is 4:3:2. Figure 1 and 2 As shown;

[0037] Metal braided flexible fiber wrapping material 2-1 wraps a single internal functional filler 2-2 to form multiple flexible functional fillers. Several flexible functional fillers are selected and placed according to the volume of different modules.

[0038] like Figure 4 As shown, the metal-woven flexible fiber wrapping material 2-1 includes carbon fiber filaments 2-1-1, TiO2 filaments 2-1-2, and 316L stainless steel wire 2-1-3; the internal functionalized filler 2-2 includes solid filler 2-2-1 and embedded microorganisms 2-2-2.

[0039] The solid filler 2-2-1 (volcanic rock with a porosity of 40-50%) embeds functional microorganisms in its porous structure. The aerobic respiration enhanced ammonia nitrogen oxidation wetland module 5 embeds nitrifying bacteria in natural volcanic rock, the facultative anaerobic denitrification wetland module 6 embeds denitrifying bacteria in natural volcanic rock, and the enhanced phosphorus removal wetland module 7 is filled with a mixture of natural volcanic rock and limestone, embedding denitrifying polyphosphate-accumulating bacteria.

[0040] The flexible functional packing module 2 refers to a module where functional packing material 2-2 is wrapped with a metal woven flexible fiber wrapping material 2-1 and placed on a rigid support structure 2-3 to form an integral flexible functional packing module 2. This allows for free assembly and disassembly according to the required functions. The combination of the rigid structure and the flexible packing structure innovates the water flow pattern. The large contact area between the internal solid packing and the water flow accelerates the transfer of dissolved oxygen. The metal woven flexible fiber wrapping material 2-1 can filter large suspended particles in domestic sewage, allowing the functional packing to be assembled and disassembled as a whole, facilitating thorough cleaning, and preventing leakage and clogging of the constructed wetland device.

[0041] The rigid support structure 2-3 has small holes distributed on its plane to facilitate the flow and transfer of sewage and the planting of wetland plants 3.

[0042] like Figure 3As shown, the perforated pipe 4 enhances the transfer of dissolved oxygen within the constructed wetland, enabling the adjustment of aerobic and facultative oxygen levels in the functional modules. The perforated pipe is connected to an air intake device in its vertical section, while the horizontal section has small holes.

[0043] The wetland plant 3 can be inserted into the holes of the rigid support structure 2-3 of the flexible functional module. The wetland plant 3 grows downward and takes root. The root capillary structure can penetrate the pores of the flexible fiber wrapping material 2-1, such as metal weave, so as to achieve the growth and rooting of the wetland plant without damaging the bag.

[0044] In this invention, the flexible functional modules are based on the dimensions of the space they occupy when stacked in a cubic artificial wetland. The specific dimensions are designed proportionally according to the size of the module space, such as... Figure 1 As shown.

[0045] The internal solid filler of the flexible functional module in the invention has a spatial porous structure, which adopts a spatial structure with alternating macropores and mesopores, and functional microorganisms are embedded on its surface.

[0046] The principle of the aerobic respiration-enhanced ammonia nitrogen oxidation wetland module is as follows:

[0047] C6H 12 O6 + 6H2O → 6CO2 + 24H + +24e - C6H 10 O5 + 6O2 → 6CO2 + 5H2O

[0048] 4NH 4+ +5O2→4NO+6H2O; 2NO+O2→2NO2; 4NO2+2H2O+O2→HNO3

[0049] The principle of the facultative nitrification wetland module is as follows:

[0050] 2NO 3- +12H + +10e - →N2+6H2O

[0051] The principle of enhanced phosphorus removal wetland module is as follows: Facultative anaerobic denitrifying polyphosphate-accumulating bacteria are embedded in the pores of the packing material. Under facultative anaerobic conditions, denitrifying polyphosphate-accumulating bacteria can use oxygen and nitrate as electron acceptors to take up a large amount of dissolved orthophosphate from wastewater and synthesize polyphosphates in the cells. The accumulation of phosphorus by polyphosphate-accumulating bacteria far exceeds the amount of phosphorus required for normal microbial growth, reaching 6% to 8% of the cell weight.

[0052] In this invention, the metal-braided flexible fiber wrapping material uses three metal wires: 316L stainless steel wire, TiO2 nanowires, and carbon fiber wires, woven in a two-up-one-down twill weave to form the wrapping material, which wraps the internal solid filler to form a flexible module. The TiO2 nanowires and carbon fiber wires form the anode and cathode micro-electrolysis principle as follows:

[0053] TiO2 nanowire anode:

[0054] C6H 12 O6 + 6H2O → 6CO2 + 24H + +24e -

[0055] Carbon fiber cathode:

[0056] 2NO 3- +12H + +10e - →N2+6H2O

[0057] The stainless steel wire, TiO2 nanowires, and carbon fiber wires used in this invention possess excellent corrosion resistance, exhibiting resistance to acid and alkali corrosion to ensure the wrapping material is not corroded, extending the module's lifespan and saving costs. Secondly, the wrapping material needs good toughness to prevent damage during installation and disassembly; stainless steel wire and carbon fiber provide this good toughness, ensuring the wrapping material is not damaged during disassembly. When weaving metal materials, high ductility is required for the metal wires; TiO2 nanowires and carbon fiber wires have good ductility, making them easy to weave. All three types of metal wires are conductive, which can also aid in the electron transfer process during contaminant removal, helping to remove contaminants from water and accelerating oxidation-reduction reactions.

[0058] The invention comprises three functional modules: an aerobic respiration-enhanced ammonia nitrogen oxidation wetland module, an anaerobic denitrification wetland module, and an enhanced phosphorus removal wetland module. Based on the quality of domestic sewage and water quality requirements, the flexible functional packing materials can be arbitrarily combined to adjust the carbon and nitrogen removal efficiency of the constructed wetland, thus achieving wetland regulation. The modules can be removed for cleaning without damaging or leaking the functional packing materials, preventing the loss of granular packing materials and clogging. They are reusable, requiring only one processing step, reducing subsequent maintenance costs and demonstrating high economic benefits.

[0059] Specifically, the following steps are included:

[0060] Step 1: First, clean the solid filler with deionized water to remove impurities, then soak it in acetone for 24 hours, place it in a muffle furnace, calcine it at 600℃ for 30 minutes, and finally soak it in deionized water for 24 hours.

[0061] Step Two: First, add 40 mL of polyvinyl alcohol (PVA) and 60 mL of sodium alginate (SA) to 1000 mL of deionized water. Then, stir the PVA / SA mixture in a thermostatically heated magnetic stirrer until dissolved. After complete dissolution, add 10 mL of powdered activated carbon (PAC). After the PVA / SA mixture cools to room temperature, mix it with an equal volume of pure bacterial solution, stirring constantly with a glass rod until completely homogeneous, forming an embedding solution for nitrifying bacteria and an embedding solution for organic matter-degrading bacteria. Immerse the solid packing material in the embedding solution, ensuring it is completely submerged for 48 hours, and then allow it to air dry naturally, completing the microbial embedding.

[0062] Step 3: Using a double-spindle wire drawing machine, 316L stainless steel and TiO2 are drawn into 25μm diameter 316L stainless steel wires and 12μm diameter TiO2 nanowires, which are then woven with 8μm carbon fiber wires using a two-up-one-down twill weave to form a flexible metal woven fiber mesh. Different functional fillers are then placed inside and the metal mesh is sealed, forming three types of flexible functional filler modules.

[0063] Step Four: Based on the quality of domestic sewage and water quality requirements, the rigid support (carbon steel frame) is combined with the flexible substrate to form a wetland substrate, thus achieving the regulation of the artificial wetland. It can be removed for cleaning when needed without damaging or leaking the functional filler, preventing the loss of granular filler, preventing blockage, and allowing for repeated use. Only one processing is required, reducing subsequent maintenance costs and resulting in high economic benefits.

Claims

1. A flexible functionalized filler, characterized in that: The flexible functionalized filler is specifically obtained by wrapping functionalized filler (2-2) with a metal braided flexible fiber wrapping material (2-1). The metal braided flexible fiber wrapping material is prepared by a weaving process, using three types of metal fibers: 25μm 316L stainless steel wire, 12μm TiO2 nanowires, and 8μm carbon fiber wires, woven in a two-up-one-down twill pattern to form a mesh-like spherical wrapping material. In the metal braided flexible fiber wrapping material, the TiO2 nanowires and carbon fiber wires form anode and cathode micro-electrolysis, purifying carbon and nitrogen pollutants in domestic sewage through oxidation-reduction reactions. The functionalized filler (2-2) includes solid filler (2-2-1) and embedded microorganisms (2-2-2). The solid filler (2-2-1) embeds microorganisms (2-2-2) in its porous structure. The solid filler (2-2-1) is volcanic rock with a porosity between 40% and 50%. The microorganisms are nitrifying bacteria or denitrifying bacteria.

2. A modular constructed wetland comprising the flexible functionalized filler as described in claim 1, characterized in that: The flexible functional filler is placed on the rigid support structure (2-3) to form an integral flexible functional filler module (2); the modular artificial wetland is composed of multiple flexible functional filler modules (2); The modular constructed wetland is composed of three parts in sequence from the inlet to the outlet: a functional aerobic respiration enhanced ammonia nitrogen oxidation wetland module, an anaerobic denitrification wetland module, and an enhanced phosphorus removal wetland module. The functional aerobic respiration enhanced ammonia nitrogen oxidation wetland module, the anaerobic denitrification wetland module, and the enhanced phosphorus removal wetland module are respectively arranged at the sewage inlet, the middle section of the sewage treatment, and the sewage outlet. The aerobic respiration enhanced ammonia nitrogen oxidation wetland module includes natural volcanic rock embedded with nitrifying bacteria, wrapping material and internal air pipes, which enhances ammonia nitrogen oxidation by embedding nitrifying bacteria in the pores of the packing material and by using the air pipes. The facultative nitrification wetland module includes natural volcanic rock for embedding denitrifying bacteria, internal air pipes, and wrapping material. By embedding nitrifying bacteria in the pores of the packing material and passing them through the air pipes, the denitrification process is enhanced to achieve nitrogen removal. The enhanced phosphorus removal wetland module packing material includes a mixture of natural volcanic rock and limestone, with facultative anaerobic denitrifying phosphorus-accumulating bacteria embedded in the pores of the packing material.

3. A method for deep purification of rural domestic sewage using the modular constructed wetland described in claim 2, characterized in that: The method is as follows: Step 1: The functionalized packing material containing embedded microorganisms is loaded into a flexible metal woven fiber wrapping material to form a flexible functionalized packing material with enhanced ammonia nitrogen oxidation, denitrification, and enhanced phosphorus removal. Step 2: The aerobic respiration enhanced ammonia nitrogen oxidation wetland module, the facultative denitrification wetland module, and the enhanced phosphorus removal wetland module are respectively arranged at the sewage inlet, the intermediate section of the sewage treatment, and the sewage outlet to form modular artificial wetlands with different functional areas. Step 3: Domestic sewage flows through modular constructed wetlands to achieve deep purification of domestic sewage; The combination of rigid support and flexible substrate creates an innovative hydraulic flow pattern within the wetland: the combination of horizontal flow between modules and vertical flow through the substrate effectively promotes the mass transfer and diffusion of dissolved oxygen, which is beneficial for ammonia oxidation; the functionalized filler can remove carbon and nitrogen pollutants from the water; the external metal woven flexible fiber wrapping material can not only intercept suspended large inorganic particles in the wastewater, but also prevent the loss of internal filler, reduce the risk of device blockage, reduce the loss of microorganisms, and improve the removal efficiency of carbon and nitrogen.

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