A High-Efficiency Constructed Wetland System for Nitrogen and Phosphorus Removal Based on Short-Range Nitrification-Anaerobic Ammonium Oxidation Co-encapsulated Particles

Abstract

This invention relates to a high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-cut nitrification-anaerobic ammonium oxidation (ATAO) co-embedded particles. The system comprises a surface flow constructed wetland, a vertical subsurface flow constructed wetland, an aeration pond, and a horizontal subsurface flow constructed wetland arranged sequentially along the water flow direction. The horizontal subsurface flow constructed wetland includes a soil layer and a layer of short-cut nitrification-anaerobic ammonium oxidation co-embedded particle filler. The main body of the composite constructed wetland system is submerged in the river channel, forming a closed corridor container through the constructed wetlands and the ecological pond frame, making full use of previously unusable space and achieving space saving. Compared with existing technologies, this invention overcomes the shortcomings of existing constructed wetlands, such as large land area, low nitrogen and phosphorus removal efficiency, and significant susceptibility to natural environmental influences. It has stronger processing capacity and better adaptability, achieving low-carbon, energy-saving, green, and highly efficient nitrogen and phosphorus removal.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles. Background Technology

[0002] Eutrophication can occur in water bodies. Eutrophication refers to water pollution caused by excessive levels of nutrients such as nitrogen (N) and phosphorus (P). Essentially, it results from an imbalance in the input and output of nutrients, leading to an imbalance in the distribution of species within the aquatic ecosystem. This causes the unchecked growth of a single species, disrupting the flow of matter and energy within the system and ultimately causing the entire aquatic ecosystem to gradually perish.

[0003] Chinese Patent Publication No. CN116495889B, entitled "An Enhanced Denitrification Constructed Wetland Treatment System and Method," discloses an enhanced denitrification constructed wetland treatment system and method. This constructed wetland treatment system includes a vertical subsurface flow constructed wetland, a horizontal subsurface flow constructed wetland, and an ecological pond. The vertical subsurface flow constructed wetland comprises a soil layer, a modified zeolite molecular sieve packing layer, an oxygen-releasing packing layer, and a ceramic packing layer; submerged plants are planted on the soil layer of the vertical subsurface flow constructed wetland. The horizontal subsurface flow constructed wetland comprises a soil layer and a limestone packing layer; emergent plants are planted on the soil layer of the horizontal subsurface flow constructed wetland. This constructed wetland treatment system can promote the growth of microorganisms, promote nitrification and denitrification within the constructed wetland treatment system, achieve deep nitrogen treatment, and improve the nitrogen removal rate. Using this constructed wetland treatment system to treat nitrogen-containing wastewater, the nitrogen removal rate is greater than 99.5%.

[0004] The system described in CN116495889B essentially employs a nitrification-denitrification process for nitrogen removal. Its advantages include high technological maturity and high ammonia nitrogen removal rate. However, its disadvantages include a large footprint, the need for an external carbon source, high economic costs, and significant susceptibility to the natural environment.

[0005] This application aims to provide a more efficient and economical composite constructed wetland system. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles. The composite constructed wetland system provided by this invention overcomes the disadvantages of existing constructed wetlands, such as large land area, low nitrogen and phosphorus removal efficiency, and great influence from the natural environment. It has stronger processing capacity and better adaptability, and can achieve low-carbon, energy-saving, green, and high-efficiency nitrogen and phosphorus removal.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] The purpose of this invention is to provide a high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles. The system includes a surface flow type constructed wetland (10), a vertical subsurface flow type constructed wetland (20), an aeration pond (30), and a horizontal subsurface flow type constructed wetland (40) arranged sequentially along the water flow direction.

[0009] Furthermore, the main body of the composite constructed wetland system is submerged in the river channel, forming a closed corridor container through the various constructed wetlands and ecological pond frames, making full use of hard-to-use spaces and thus saving space. Along the direction of water flow, it sequentially includes: surface flow constructed wetland, vertical subsurface flow constructed wetland, aeration pond, and horizontal subsurface flow constructed wetland.

[0010] Furthermore, the surface flow type artificial wetland (10) is provided with a soil layer (first soil layer), on which emergent plants are planted.

[0011] Furthermore, the vertical subsurface flow constructed wetland (20) includes a second soil layer (21), a biological ceramsite filler layer (22), and modified rice husk activated carbon filler columns (23). Submerged plants (24) are planted on the second soil layer (21).

[0012] Furthermore, the aeration pond (30) is provided with an inlet pool (31), an aeration fountain (32), a water-blocking layer (33), and an outlet pool (34) from bottom to top.

[0013] Furthermore, the horizontal subsurface flow constructed wetland (40) is provided with a third soil layer (41) and a short-cut nitrification-anaerobic ammonium oxidation co-embedded granular filler layer (42) from top to bottom; a second emergent plant (43) is planted on the third soil layer (41).

[0014] Furthermore, the thickness ratio of the second soil layer (21) to the biological ceramsite filler layer (22) is 1:2; the thickness ratio of the third soil layer (41) to the short-cut nitrification-anaerobic ammonia oxidation co-embedded particle filler layer (42) is 1:2.

[0015] Furthermore, the structure of the composite constructed wetland is designed as follows:

[0016] Firstly, modified rice husk activated carbon packing columns are set in the soil layer and packing layer of the vertical subsurface flow constructed wetland. The modified rice husk activated carbon packing columns are composed of modified rice husk activated carbon packing. The modified rice husk activated carbon packing has a large specific surface area and is rich in micropores and mesopores. Through processes such as free diffusion between molecules and within pores, it has good adsorption performance for phosphorus. After adsorption saturation, it can also be used as a bio-fertilizer in farmland to achieve resource recycling.

[0017] Secondly, aeration fountains are installed in the aeration pond to raise the effluent water level of the vertical subsurface flow constructed wetland and replenish the dissolved oxygen in the effluent of the vertical subsurface flow constructed wetland, ensuring sufficient oxygen in the subsequent horizontal subsurface flow constructed wetland and improving the nitrification effect.

[0018] Thirdly, the composite constructed wetland denitrification process adopts short-cut nitrification-anaerobic ammonium oxidation. Compared with the traditional constructed wetland nitrification-denitrification denitrification method, the short-cut nitrification-anaerobic ammonium oxidation route can theoretically save 100% of carbon source, reduce sludge production by 90%, and reduce the amount of greenhouse gas N2O produced, thus achieving low-carbon, energy-saving, green, and efficient denitrification.

[0019] Preferably, in the horizontal subsurface flow constructed wetland, a short-cut nitrification-anammox co-embedded granular packing layer is provided. The short-cut nitrification-anammox co-embedded granular packing layer is composed of short-cut nitrification-anammox co-embedded granular packing. The inner layer of the short-cut nitrification-anammox co-embedded granules encapsulates anammox bacteria (AMX), and the outer layer encapsulates nitrite-oxidizing bacteria (AOB).

[0020] Short-range nitration occurs in the outer layer:

[0021]

[0022] Anaerobic ammonia oxidation occurs in the inner layer:

[0023]

[0024] By layering and embedding anaerobic ammonia-oxidizing bacteria and nitrifying bacteria, immobilization is achieved, reducing the impact of external environmental shocks on the denitrification performance of microorganisms. The outer layer of aerobic nitrifying bacteria consumes oxygen and creates an anaerobic environment inside the co-embedded particles, while simultaneously providing nitrite nitrogen to the inner layer of anaerobic ammonia-oxidizing bacteria, ensuring the normal growth of the anaerobic ammonia-oxidizing bacteria and achieving synergistic denitrification.

[0025] Furthermore, the workflow of the composite constructed wetland is as follows:

[0026] When river water enters the composite constructed wetland system, it first passes through a surface flow constructed wetland. The soil layer of the surface flow constructed wetland is planted with emergent plants to intercept suspended solids and other pollutants in the water, preventing blockages. At the same time, it serves as a buffer pool for the entire system, providing a stable outflow and avoiding shocks that could affect the subsequent treatment effects of the system.

[0027] Then, we entered the vertical subsurface flow constructed wetland. The soil layer of the vertical subsurface flow constructed wetland is planted with submerged plants, which can release oxygen in the water and inhibit the denitrification reaction. The biological ceramsite filler layer and the modified rice husk activated carbon filler column have a strong adsorption capacity for phosphorus, but a poor adsorption effect on ammonia nitrogen. While effectively adsorbing and removing phosphorus, it ensures the ammonia nitrogen content in the horizontal subsurface flow constructed wetland.

[0028] The effluent from the vertical subsurface flow constructed wetland enters the inlet pool of the aeration pond, and then enters the outlet pool through the aeration fountain. This raises the water level, replenishes dissolved oxygen in the water, inhibits denitrification, enhances nitrification, and also serves a landscaping function.

[0029] The effluent from the aeration pond enters a horizontal subsurface flow constructed wetland via a water distribution system. Emergent plants are planted in this wetland; their stems grow upright in the water, while their roots or rhizomes penetrate the mud. These plants have well-developed root systems and a certain oxygen-carrying capacity, providing sufficient dissolved oxygen to the underlying short-cut nitrification-anammox co-embedded granular packing layer. The lower layer of short-cut nitrification-anammox co-embedded granules undergoes a short-cut nitrification-anammox reaction, effectively and efficiently removing ammonia nitrogen from the water. Finally, the effluent is discharged directly into the river.

[0030] Furthermore, the preparation method of the bio-ceramic particles is as follows:

[0031] The raw material ratio is 75% fly ash, 15% cement, and 10% bentonite. After mixing the raw materials, the well-mixed powder is gradually fed into a disc powder granulator, and water is sprayed onto the powder as needed. When the diameter of the ceramsite pellets reaches 6-8 mm, they are taken out, and the processed ceramsite is stacked in a thin layer, placed in a sealed container, and kept moist by spraying water. After natural curing for 28 days, the bio-ceramsite is obtained.

[0032] Furthermore, the preparation method of the modified rice husk activated carbon is as follows:

[0033] Rice husks and zinc chloride solution (55% by mass) were mixed evenly at a material-to-liquid ratio of 1:1 and placed in a 105℃ constant temperature drying oven. The dried and carbonized rice husks were placed in a tubular resistance furnace and heated from room temperature to 500℃ at a set temperature of 10℃ / min, held for 60 min, and then allowed to cool naturally to room temperature, with high-purity N2 passed through at a flow rate of 200 mL / min for protection. The activated product was removed, 0.1 mol / L hydrochloric acid was added, and the mixture was placed in an 80℃ constant temperature water bath and stirred for 30 min. The activated product after acid washing was repeatedly rinsed with deionized water until the pH was about neutral. The sample was placed in an 80℃ drying oven and allowed to dry completely before being allowed to cool naturally to room temperature and passed through a 100-mesh sieve to obtain the modified rice husk activated carbon.

[0034] Furthermore, the method for preparing the short-range nitration-anaerobic ammonium oxidation co-encapsulated particles is as follows:

[0035] Take 12% PVA (polyvinyl alcohol) by volume, swell it in deionized water at room temperature for 2 hours, and then dissolve it in a 90°C water bath. Add 2% SA (sodium alginate) by volume, stir until completely mixed, and then autoclave at 121°C for 30 minutes. After cooling to room temperature, add an equal volume of Anammox sludge and stir thoroughly. Use a syringe to slowly drip the embedded bacterial gel solution into a saturated boric acid and 1% CaCl2 solution, and crosslink for 1 hour. Remove the embedded particles, rinse three times with deionized water, and then phosphorylate them in 0.5 mol / L KH2PO4 solution for 1 hour. Rinse three more times with deionized water and store in anaerobic ammonia oxidation medium at 4°C for later use. Take 6% PVA by volume, swell it in deionized water at room temperature for 2 hours, and then dissolve it in a 90°C water bath. Add 4% SA by volume, stir until completely mixed, and then autoclave at 121°C for 30 minutes. After cooling to room temperature, an equal volume of AOB sludge was added and stirred thoroughly. Anammox-encapsulated particles were added to the mixture, immersing them in the mixture to form an AOB gel layer on the surface. The particles were then removed and added to a saturated boric acid and 1% CaCl2 solution for crosslinking for 1 hour. The encapsulated particles were then removed, rinsed three times with deionized water, and phosphorylated in a 0.5 mol / L KH2PO4 solution for 1 hour. They were then rinsed three more times with deionized water to obtain the short-cut nitrification-anaerobic ammonium oxidation co-encapsulated particles.

[0036] Preferably, the vertical subsurface flow constructed wetland is treated with a compound microbial agent, which includes ammonifying bacteria and nitrifying bacteria.

[0037] Preferably, the compound microbial agent and water are mixed at a ratio of (0.005-5) g: 1 L and then added to the vertical subsurface flow constructed wetland.

[0038] Preferably, the water pump of the aeration fountain (32) is also connected to two flushing pipes, which lead to the vertical subsurface flow constructed wetland and the horizontal subsurface flow constructed wetland, respectively.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-cut nitrification-anaerobic ammonium oxidation co-encapsulated particles provided by this invention adopts a short-cut nitrification-anaerobic ammonium oxidation process. Compared with the traditional constructed wetland nitrification-denitrification nitrogen removal method, the short-cut nitrification-anaerobic ammonium oxidation route can theoretically save 100% of the carbon source and reduce the sludge production rate by 90%. It does not require the addition of external carbon source and retains the generated sludge, thus achieving low-carbon, energy-saving, green and efficient nitrogen removal.

[0041] 2. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-embedded particles provided by the present invention can achieve high-efficiency nitrogen removal in the same structure while reducing microbial loss and mitigating the inhibitory effect of external environmental shocks on microbial nitrogen removal, thus significantly reducing the system's footprint and improving nitrogen removal capacity.

[0042] 3. The high-efficiency nitrogen and phosphorus removal composite artificial wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles provided by this invention has modified rice husk activated carbon with good phosphorus adsorption performance. After adsorption saturation, it can also be used as a bio-fertilizer in farmland to realize resource recycling.

[0043] 4. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles provided by this invention, with the setting of aeration fountain, gives the system a new function of landscaping in addition to its water treatment function; planting a variety of plants in the soil layer of the system realizes the organic combination of water treatment and landscaping. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of a high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles, as provided in Example 1 of this invention.

[0045] Figure 2 This is a schematic diagram of the structure of a high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles, as provided in Example 3 of the present invention.

[0046] Figure 3 The nitrogen and phosphorus removal effect diagrams of the high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles provided in Examples 1 and 2 of this invention.

[0047] Explanation of the labels in the diagram:

[0048] 10. Surface flow constructed wetland; 11. First soil layer; 12. First emergent plants; 20. Vertical subsurface flow constructed wetland; 21. Second soil layer; 22. Bioceramic filler layer; 23. Modified rice husk activated carbon filler column; 24. Submerged plants; 30. Aeration pond; 31. Inlet pool; 32. Aeration fountain; 33. Water barrier layer; 34. Outlet pool; 35. Flushing pipe; 40. Horizontal subsurface flow constructed wetland; 41. Third soil layer; 42. Short-cut nitrification-anaerobic ammonium oxidation co-embedded granular filler layer; 43. Second emergent plants. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0050] Any preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0051] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0054] In the following examples, the fly ash is Grade II fly ash, the cement is P·I 42.5 standard silicate cement, and the bentonite is sodium-based bentonite, all of which are commercially available products.

[0055] Example 1

[0056] This embodiment provides a highly efficient nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles, such as... Figure 1As shown, along the water flow direction, there are surface flow type constructed wetlands 10, vertical subsurface flow type constructed wetlands 20, aeration ponds 30 and horizontal subsurface flow type constructed wetlands 40.

[0057] The surface flow type constructed wetland 10 includes a first soil layer 11, on which emergent plants 12 are planted.

[0058] The vertical subsurface flow type artificial wetland 20 is provided with a soil layer 21 and a biological ceramsite filler layer 22 from top to bottom. It is also provided with modified rice husk activated carbon filler columns 23. The modified rice husk activated carbon filler columns 23 are set vertically, with the upper end extending into the second soil layer 21 and the lower end extending into the biological ceramsite filler layer 22. Submerged plants 24 are planted on the second soil layer 21.

[0059] The aeration pond 30 is arranged from bottom to top as follows: inlet pool 31, aeration fountain 32, water-blocking layer 33, and outlet pool 34.

[0060] A horizontal subsurface flow type constructed wetland 40 is provided from top to bottom with a third soil layer 41 and a short-cut nitrification-anaerobic ammonium oxidation co-embedded granular filler layer 42; emergent plants 43 are planted on the third soil layer 41.

[0061] The thickness ratio of the second soil layer 21 to the biological ceramsite filler layer 22 is 1:2; the thickness ratio of the third soil layer 41 to the short-cut nitrification-anaerobic ammonium oxidation co-embedded granular filler layer 42 is also 1:2. When river water enters the composite constructed wetland system, it first passes through the surface flow constructed wetland 10. The first soil layer 11 of the surface flow constructed wetland 10 is planted with the first emergent plant 12 to intercept suspended solids in the water and prevent clogging; at the same time, it serves as a buffer pool for the entire system, providing stable effluent and avoiding shocks that could affect the subsequent treatment effect of the system.

[0062] Then, the vertical subsurface flow constructed wetland 20 is introduced. The second soil layer 21 of the vertical subsurface flow constructed wetland 20 is planted with submerged plants 24, which can release oxygen in the water and inhibit denitrification. The biological ceramsite filler layer 22 and the modified rice husk activated carbon filler column 23 both have a strong adsorption capacity for phosphorus, but a poor adsorption effect on ammonia nitrogen. While effectively adsorbing and removing phosphorus, the ammonia nitrogen content in the horizontal subsurface flow constructed wetland 40 is maintained.

[0063] The water from the vertical subsurface flow constructed wetland 20 enters the inlet pool 31 of the aeration pond 30, and then enters the outlet pool 34 through the aeration fountain 32. This raises the water level, replenishes dissolved oxygen in the water, inhibits denitrification, enhances nitrification, and also serves as a landscaping and beautification function.

[0064] The effluent from the aeration pond 30's effluent pool 34 enters the horizontal subsurface flow constructed wetland 40 via a water distribution system. A second emergent plant 43 is planted on the third soil layer 41 of the horizontal subsurface flow constructed wetland 40. The stems of the emergent plant grow upright in the water, while its roots or rhizomes penetrate the mud. The emergent plant has a well-developed root system and a certain oxygen-carrying capacity, providing sufficient dissolved oxygen for the lower short-cut nitrification-anaerobic ammonium oxidation co-embedded particle packing layer 42. The lower short-cut nitrification-anaerobic ammonium oxidation co-embedded particles undergo short-cut nitrification-anaerobic ammonium oxidation reactions, removing 76% of ammonia nitrogen and 86% of total nitrogen from the effluent compared to the influent, achieving green and efficient ammonia nitrogen removal. Finally, the effluent is directly discharged into the river.

[0065] The bio-ceramic filler layer 22 comprises bio-ceramic particles, and the preparation method of the bio-ceramic particles is as follows:

[0066] The raw material ratio is 75% fly ash, 15% cement, and 10% bentonite. After mixing the raw materials, the well-mixed powder is gradually fed into a disc powder granulator, and water is sprayed onto the powder as needed. When the diameter of the ceramsite pellets reaches 6-8 mm, they are taken out, and the processed ceramsite is stacked in a thin layer, placed in a sealed container, and kept moist by spraying water. After natural curing for 28 days, the bio-ceramsite is obtained.

[0067] The modified rice husk activated carbon packing column 23 comprises modified rice husk activated carbon, and the preparation method of the modified rice husk activated carbon is as follows:

[0068] Rice husks and zinc chloride solution (55% by mass) were mixed evenly at a material-to-liquid ratio of 1:1 and placed in a 105℃ constant temperature drying oven. The dried and carbonized rice husks were placed in a tubular resistance furnace and heated from room temperature to 500℃ at a set temperature of 10℃ / min, held for 60 min, and then allowed to cool naturally to room temperature, with high-purity N2 passed through at a flow rate of 200 mL / min for protection. The activated product was removed, 0.1 mol / L hydrochloric acid was added, and the mixture was placed in an 80℃ constant temperature water bath and stirred for 30 min. The activated product after acid washing was repeatedly rinsed with deionized water until the pH was about neutral. The sample was placed in an 80℃ drying oven and allowed to dry completely before being allowed to cool naturally to room temperature and passed through a 100-mesh sieve to obtain the modified rice husk activated carbon.

[0069] The short-range nitrification-anammox co-embedded particle packing layer 42 includes short-range nitrification-anammox co-embedded particles, and the preparation method of the short-range nitrification-anammox co-embedded particles is as follows:

[0070] 12% PVA (by volume) was swelled in deionized water at room temperature for 2 hours, then dissolved in a 90°C water bath. 2% SA (by volume) was added, and the mixture was stirred until completely combined. The mixture was then autoclaved at 121°C for 30 minutes. After cooling to room temperature, an equal volume of Anammox sludge (from a pilot-scale anaerobic ammonia oxidation tank at a wastewater treatment plant in Xi'an) was added and stirred thoroughly. The encapsulated bacterial gel solution was slowly dripped into a saturated boric acid and 1% CaCl2 solution using a syringe, and crosslinked for 1 hour. The encapsulated particles were removed, rinsed three times with deionized water, and then phosphorylated in 0.5 mol / L KH2PO4 solution for 1 hour. They were then rinsed three more times with deionized water and stored in anaerobic ammonia oxidation medium at 4°C for later use. 6% PVA (by volume) was swelled in deionized water at room temperature for 2 hours, then dissolved in a 90°C water bath. 4% SA (by volume) was added, and the mixture was stirred until completely combined. The mixture was then autoclaved at 121°C for 30 minutes. After cooling to room temperature, an equal volume of AOB sludge (from the AO tank of a wastewater treatment plant in Xi'an) was added and stirred thoroughly. Anammox-encapsulated particles were added to the mixture, immersing them in the mixture to form an AOB gel layer on the surface. The particles were then removed and added to a saturated boric acid and 1% CaCl2 solution for crosslinking for 1 hour. The encapsulated particles were then removed, rinsed three times with deionized water, and phosphorylated in a 0.5 mol / L KH2PO4 solution for 1 hour. After rinsing three more times with deionized water, the short-cut nitrification-anaerobic ammonium oxidation co-encapsulated particles were obtained.

[0071] Example 2

[0072] Example 2 has the following additional features compared to Example 1:

[0073] In the vertical subsurface flow constructed wetland 20, a compound microbial agent is also added. The compound microbial agent includes ammonifying bacteria and nitrifying bacteria (from a stably operating nitrification reactor; in this embodiment, the ammonifying bacteria and nitrifying bacteria have not been modified). The agent is mixed with water at a ratio of (0.005-5) g: 1 L and added to the vertical subsurface flow constructed wetland.

[0074] After the addition of the compound microbial agent, the agent adheres to the bioceramic granular packing layer 22 of the vertical subsurface flow constructed wetland 20, pre-ammonizing and pre-nitrifying the raw water. This converts some of the organic matter and ammonia nitrogen in the high-ammonia nitrogen raw water into ammonia nitrogen and nitrate nitrogen, facilitating further denitrification in the subsequent short-cut nitrification-anaerobic ammonia oxidation co-encapsulated granular layer 42. Simultaneously, the lower dissolved oxygen at the bottom of the vertical subsurface flow constructed wetland 20 inhibits pre-ammoniation and pre-nitrification, retaining some ammonia nitrogen in the raw water to meet the ammonia nitrogen requirements of the subsequent co-encapsulated granules. Example 2 is more suitable for denitrification and phosphorus removal from high-ammonia nitrogen raw water, removing 84% of ammonia nitrogen and 87% of total nitrogen from the effluent compared to the influent.

[0075] Example 3

[0076] Example 3, based on Example 1, also has the following features:

[0077] like Figure 3 As shown, in the aeration pond 30, the aeration fountain 32 water pump is also connected to the flushing pipe 35, which leads to the horizontal subsurface flow type artificial wetland 40.

[0078] The function of flushing pipe 35 is to clear blockages in the artificial wetland filler through the impact of water flow, thereby preventing the anaerobic environment and reduced treatment efficiency caused by blockage of the artificial wetland.

[0079] like Figure 3 As shown, days 11 to 20 represent the treatment results of Example 1, and days 21 to 30 represent the treatment results of Example 2. After stabilization, Example 1 achieved an ammonia nitrogen removal rate of 79% and a total nitrogen removal rate of 86%; after stabilization, Example 2 achieved an ammonia nitrogen removal rate of 84% and a total nitrogen removal rate of 87%.

[0080] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles, characterized in that, The system includes a surface flow type constructed wetland (10), a vertical subsurface flow type constructed wetland (20), an aeration pond (30), and a horizontal subsurface flow type constructed wetland (40) arranged sequentially along the water flow direction; The surface flow type artificial wetland (10) includes a first soil layer (11), on which a first emergent plant (12) is planted; The vertical subsurface flow type artificial wetland (20) is provided with a second soil layer (21) and a biological ceramsite filler layer (22) from top to bottom, and is also provided with modified rice husk activated carbon filler column (23). Submerged plants (24) are planted on the second soil layer (21). The aeration pond (30) is provided with an inlet pool (31), an aeration fountain (32), a water-blocking layer (33), and an outlet pool (34) from bottom to top. The horizontal subsurface flow constructed wetland (40) is provided with a third soil layer (41) and a short-range nitrification-anaerobic ammonium oxidation co-embedded granular filler layer (42) from top to bottom; a second emergent plant (43) is planted on the third soil layer (41).

2. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles as described in claim 1, characterized in that, The thickness ratio of the second soil layer (21) to the bio-ceramic filler layer (22) is 1:2; The thickness ratio of the third soil layer (41) to the short-range nitrification-anaerobic ammonium oxidation co-embedded particle filler layer (42) is 1:

2.

3. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles as described in claim 1, characterized in that, The vertical subsurface flow constructed wetland (20) is also supplemented with compound microbial agents; The compound microbial agent includes ammonifying bacteria and nitrite-oxidizing bacteria.

4. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 3, characterized in that, The compound microbial agent and water are mixed at a ratio of (0.005-5) g: 1 L and added to the vertical subsurface flow type constructed wetland (20).

5. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 1, characterized in that, The aeration pond (30) is equipped with an aeration fountain (32); The aeration fountain (32) includes a water pump.

6. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 5, characterized in that, The water pump of the aeration fountain (32) is also connected to two flushing pipes (35), which lead to the vertical subsurface flow constructed wetland (20) and the horizontal subsurface flow constructed wetland (40), respectively.

7. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 1, characterized in that, The bio-ceramic filler layer (22) comprises bio-ceramic particles; The bio-ceramsite The raw material ratio is 75% fly ash, 15% cement, and 10% bentonite.

8. A high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 7, characterized in that, The preparation method of the bio-ceramic granules is as follows: After mixing and stirring the raw materials, water is sprayed into the mixed powder. When the diameter of the ceramsite pellets reaches 6-8 mm, they are taken out and stacked in a thin layer. They are then placed in a sealed container and kept moist by spraying water. After 28 days of natural curing, the bio-ceramsite is obtained.

9. The high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 1, characterized in that, The modified rice husk activated carbon packing column (23) includes modified rice husk activated carbon; The modified rice husk activated carbon is prepared as follows: Rice husks and zinc chloride solution were mixed evenly at a ratio of 1:1 and placed in a constant temperature drying oven at 105℃ to obtain dried carbonized rice husks. The dried carbonized rice husks were placed in a tube-type resistance furnace and heated from room temperature to 500℃ at a rate of 10℃ / min according to the set program. The temperature was maintained for 60 minutes and then naturally cooled to room temperature. High-purity N2 was introduced for protection during the process to obtain the activated product. The activated product was removed, 0.1 mol / L hydrochloric acid was added, and the mixture was placed in an 80℃ constant temperature water bath and stirred for 30 min to obtain the acid-washed activated product. The acid-washed activated product was repeatedly rinsed with deionized water until the pH was neutral to obtain the sample. The sample was placed in an 80℃ drying oven and allowed to dry completely before being naturally cooled to room temperature and passed through a 100-mesh sieve to obtain the modified rice husk activated carbon.

10. A high-efficiency nitrogen and phosphorus removal composite constructed wetland system based on short-range nitrification-anaerobic ammonium oxidation co-encapsulated particles according to claim 1, characterized in that, The short-range nitration-anaerobic ammonium oxidation co-embedded particle packing layer (42) includes short-range nitration-anaerobic ammonium oxidation co-embedded particles; The method for preparing the short-range nitration-anaerobic ammonium oxidation co-encapsulated particles is as follows: 12% polyvinyl alcohol (V / V) was swelled in deionized water at room temperature for 2 hours, then dissolved in a 90°C water bath. 2% sodium alginate (V / V) was added and stirred until completely mixed. The mixture was then sterilized at 121°C for 30 minutes. After cooling to room temperature, an equal volume of Anammox sludge was added and stirred thoroughly. The encapsulated bacterial gel solution was dripped into a saturated boric acid and 1% CaCl2 solution using a syringe and crosslinked for 1 hour. The encapsulated particles were removed, rinsed with deionized water, and then subjected to a 0.5 mol / L... Phosphorylation was performed in KH2PO4 solution for 1 hour; then the particles were rinsed with deionized water to obtain Anammox-embedded particles, which were stored in anaerobic ammonia oxidation medium at 4°C for later use; 6% polyvinyl alcohol was swelled in deionized water at room temperature for 2 hours, and then dissolved in a water bath at 90°C; 4% sodium alginate was added, and the mixture was stirred until completely mixed, then sterilized at 121°C for 30 minutes; after cooling to room temperature, an equal volume of AOB sludge was added and stirred evenly; Anammox-embedded particles were added to the mixture to immerse them in the mixture and form an AOB gel layer on the surface; then the Anammox-embedded particles with the AOB gel layer on the surface were removed and added to a saturated boric acid and 1% CaCl2 solution for crosslinking for 1 hour; the crosslinked embedded particles were removed, rinsed with deionized water, and then phosphorylated in 0.5 mol / L KH2PO4 solution for 1 hour; then rinsed with deionized water to obtain the short-path nitrification-anaerobic ammonia oxidation co-embedded particles.

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