Enhanced denitrification system of constructed wetland based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton and application and method thereof

Abstract

The application discloses a long-wool cotton enzyme-based dynamic regulation and control carbon source artificial wetland enhanced denitrification system, application and method thereof, and comprises a cellulase solution storage and conveying device, a nitrogen-containing wastewater storage and conveying device, and a wetland filler system.The cellulase solution storage and conveying device comprises a cellulase solution storage container and a first peristaltic pump connected through a first pipeline.The nitrogen-containing wastewater storage and conveying device comprises a nitrogen-containing wastewater storage container and a second peristaltic pump connected through a second pipeline.The wetland filler system comprises an upper filler layer, a main substrate layer, a lower filler layer and a long-wool cotton containing pipeline located in the main substrate layer.The upper end of the long-wool cotton containing pipeline is connected to the first peristaltic pump through a third pipeline, and the upper filler layer is connected to the second peristaltic pump through a fourth pipeline.The application uses cellulase to enzymatically hydrolyze long-wool cotton as a carbon source, overcomes the low release efficiency of natural cellulose as a carbon source and the high cost of liquid or biodegradable polymer carbon source, and realizes the transformation of waste into treasure since the long-wool cotton is derived from waste textiles.

Description

Technical Field

[0001] This application relates to the field of water pollution treatment technology, and more specifically, to an artificial wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton and dynamic regulation of carbon sources, as well as its application and method. Background Technology

[0002] Currently, many slightly polluted water bodies (including receiving rivers, wastewater treatment plant effluent, urban surface runoff, and agricultural non-point source drainage) meet the limits of the "Urban Wastewater Treatment Plant Pollutant Discharge Standard," but their core indicators generally exceed the Class V water quality requirements of the "Surface Water Environmental Quality Standard." These water bodies have two typical characteristics: large water volume and a structural lack of carbon sources, specifically manifested as a scarcity of bioavailable organic matter and an imbalance in the carbon-to-nitrogen ratio. In treatment practice, mainstream technologies rely on the direct addition of liquid carbon sources to achieve deep denitrification. While this method demonstrates advantages in short-term operation and maintenance such as low investment and ease of operation, its long-term sustainability has significant drawbacks, including high operating costs due to continuous carbon source consumption, pressure from excessive sludge disposal, and a surge in greenhouse gas emissions.

[0003] Solid-phase antinitrification technology for treating nitrogen-containing wastewater with low carbon-to-nitrogen ratios is mainly developed based on natural solid-phase carbon sources or artificially synthesized carbon sources. Currently, the most studied natural solid-phase carbon sources are inexpensive and readily available agricultural wastes, such as sawdust, straw, rice husks, corn cobs, and peanut shells. However, because cellulose and hemicellulose in litter lose carbon during long-term weathering and decomposition in the natural environment, the initial total carbon content of the hydrolysate is usually insufficient to meet the continuous carbon release requirements, easily leading to a decline in subsequent denitrification efficiency. If fresh plants are directly used as a supplementary carbon source, new problems arise: on the one hand, the high pigment content of fresh green plant tissues continuously dissolves during water immersion, not only causing a significant increase in water color, but also potentially increasing the treatment load on the denitrification system due to their high nitrogen content; on the other hand, the inherent carbon release characteristics of plant materials exhibit significant stage differences—initial carbon release shows explosive growth, while the later stages show a sharp decline, resulting in significant fluctuations in carbon source supply.

[0004] In view of the above technical problems, those skilled in the art are dedicated to researching a new type of high-efficiency denitrification system suitable for nitrogen-containing wastewater with low carbon-to-nitrogen ratio. Summary of the Invention

[0005] Based on the shortcomings of the existing technology, the purpose of this application is to solve the problem of low carbon-nitrogen ratio in traditional constructed wetlands by using cellulase to efficiently degrade cellulose into oligosaccharides or monosaccharides as an organic carbon source, so as to provide a constructed wetland enhanced denitrification system based on the enzymatic hydrolysis of long-staple cotton and dynamically regulated carbon source, as well as its application and method.

[0006] In constructed wetlands, nitrogen removal is mainly accomplished through two processes: autotrophic denitrification and heterotrophic denitrification. Heterotrophic denitrification is the process by which denitrifying bacteria, under anaerobic conditions, utilize organic carbon sources as electron donors to gradually reduce nitrate (NO3-) to nitrogen gas (N2). Glucose (C6H2O) is used as a precipitator in this process. 12 Taking O6 as an example, the chemical reaction formula for heterotrophic denitrification is:

[0007] 5C6H 12 O6+24 NO3 - →12 N2↑+30 CO2↑+18 H2O+24 OH -

[0008] Long-staple cotton (such as Xinjiang long-staple cotton) is a potential carbon source material due to its high cellulose content (>90%), but its natural crystal structure limits its bioavailability. Cellulase can efficiently degrade cellulose into oligosaccharides or monosaccharides, which can serve as an organic carbon source for denitrification in constructed wetlands, thus ensuring the efficient nitrogen removal capacity of constructed wetlands for treating low C / N wastewater.

[0009] The main components of long-staple cotton enzyme hydrolysate are cellulose hydrolysis products (such as glucose, cellobiose, cellooligosaccharides and other soluble organic matter). As a carbon source for constructed wetlands, it has the characteristics of wide availability, low cost and easy degradation. It is especially suitable for continuously releasing carbon sources in constructed wetlands to maintain the long-term operation of the denitrification process. Its application can effectively improve the removal efficiency of nitrates in wetland systems and reduce the risk of eutrophication. Therefore, it can be used as a carbon source and energy source for denitrifying bacteria.

[0010] More specifically, in a first aspect, this application provides an artificial wetland enhanced denitrification system based on the dynamic regulation of carbon sources through enzymatic hydrolysis of long-staple cotton, comprising: a cellulase solution storage and transportation device, including a cellulase solution storage container and a first peristaltic pump connected by a first pipe; a nitrogen-containing wastewater storage and transportation device, including a nitrogen-containing wastewater storage container and a second peristaltic pump connected by a second pipe; and a wetland packing system, including an upper packing layer, a main matrix layer, a lower packing layer, and a long-staple cotton receiving pipe located in the main matrix layer, wherein the upper end of the long-staple cotton receiving pipe is connected to the first peristaltic pump through a third pipe, and the upper packing layer is connected to the second peristaltic pump through a fourth pipe.

[0011] Preferably, the long-staple cotton receiving pipe has an open top structure, and liquid outlet holes are provided on the side wall and bottom of the long-staple cotton receiving pipe. The diameter of the liquid outlet holes is 8-12mm and the porosity is 30-50%.

[0012] Preferably, the long-staple cotton receiving conduit is used to fill pretreated long-staple cotton, which is derived from waste textiles.

[0013] Preferably, the angle between the axis of the long-staple cotton receiving pipe and the horizontal plane is 15-75°.

[0014] Preferably, the cellulase solution storage container is used to store a cellulase solution with a concentration of 2.5-4 mg / L and a pH of 6.5-7.5.

[0015] Preferably, the upper filler layer is planted with wetland plants; and / or the lower filler layer is equipped with a porous water outlet pipe, wherein the porous water outlet pipe has a pore diameter of 1-2 mm and a pore density of 8-12 pores / 10 cm. 2 The wall of the porous water outlet pipe is covered with 100-200 mesh nylon mesh.

[0016] Preferably, the upper filler layer comprises quartz sand with a particle size of 2-4 mm, the main matrix layer comprises quartz sand with a particle size of 4-6 mm, and the lower filler layer comprises quartz sand with a particle size of 6-8 mm.

[0017] Preferably, the thickness ratio of the upper filler layer, the main matrix layer, and the lower filler layer is 1:2-4:1-1.5.

[0018] Secondly, this application provides an application of an artificial wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources in the treatment of nitrogen-containing wastewater.

[0019] Thirdly, this application provides an enhanced denitrification method for constructed wetlands based on enzymatic hydrolysis of long-staple cotton and dynamic regulation of carbon sources. The denitrification method utilizes an enhanced denitrification system for constructed wetlands based on enzymatic hydrolysis of long-staple cotton and dynamic regulation of carbon sources. The denitrification method includes the following steps:

[0020] S1. Place a cellulase solution with a concentration of 2.5-4 mg / L in a cellulase solution storage container and adjust the pH to 6.5-7.5;

[0021] S2. Place the nitrogen-containing wastewater in a wastewater storage container;

[0022] S3. Fill the long-staple cotton containing the pretreated long-staple cotton into the long-staple cotton receiving pipe;

[0023] S3. Start the first and second peristaltic pumps;

[0024] The volumes of cellulase solution and nitrogen-containing wastewater entering the wetland packing system satisfy the following formula:

[0025]

[0026] Where C / N is the carbon-nitrogen ratio, C a V represents the COD value of the cellulase solution measured before addition. a V represents the volume of cellulase solution added. b1C represents the influent volume of nitrogen-containing wastewater. b1 The COD value of nitrogen-containing wastewater, C b2 The nitrogen concentration of the nitrogen-containing wastewater; and,

[0027] The flow rate of the first peristaltic pump (12) is:

[0028] The flow rate of the second peristaltic pump (22) is:

[0029] V is the effective volume of the constructed wetland, a is the hydraulic retention time of nitrogen-containing wastewater or the hydraulic retention time of cellulase solution, and n is the volume ratio of nitrogen-containing wastewater to cellulase solution.

[0030] The technical solution of this application achieves the following technical effects:

[0031] 1. This application uses soluble organic matter such as glucose, cellobiose, and cellooligosaccharide produced by cellulase hydrolysis of long-staple cotton as a carbon source to continuously and stably provide organic carbon source for denitrifying bacteria in constructed wetlands, promote the reduction and conversion of nitrate nitrogen in nitrogen-containing wastewater, and overcome the limitations of low carbon source release efficiency when natural cellulose is used as a carbon source and high addition cost of liquid or biodegradable polymer carbon sources.

[0032] 2. The denitrification system of this application utilizes a novel constructed wetland design, employing cellulase hydrolysate as the carbon source for denitrification, and combining this with the root activity of wetland plants to create an effective ecological reaction environment, thus promoting the removal of nitrate nitrogen. This system boasts advantages such as low energy consumption, simple operation, efficient utilization of carbon sources, and resource utilization of waste. Simultaneously, it achieves highly efficient nitrogen removal from low-carbon wastewater, exhibiting clean, efficient, and environmentally friendly characteristics.

[0033] 3. The long-staple cotton in this application comes from waste textiles, which can come from waste clothing, waste textiles from home, scraps and waste materials from the production process of textile and garment factories, etc., thus realizing the effects of recycling waste, turning waste into treasure and treating waste with waste.

[0034] 4. The denitrification system and method of this application possess high efficiency and stability in utilizing carbon sources. Traditional liquid carbon sources (such as glucose and sodium acetate) are easily consumed rapidly, requiring frequent additions and prone to secondary pollution. Long-staple cotton fibers, however, are characterized by high cellulose content and a dense structure. After hydrolysis by cellulase, they release a large amount of soluble organic carbon (such as glucose), providing a highly efficient electron donor for denitrifying bacteria and significantly improving denitrification efficiency. Through enzymatic control, the long-staple cotton enzymatic hydrolysate can form a slow-release system, extending the carbon source supply cycle and reducing operating costs.

[0035] 5. The denitrification system and method of this application are environmentally friendly and resource-efficient. Long-staple cotton, as a natural plant material, is widely available and inexpensive. Its hydrolysate does not contain additional chemical additives, avoiding the toxicity risks of traditional carbon sources (such as methanol), and meets the sustainable needs of ecological restoration. Compared with plant carbon sources such as corn cobs that require physical or chemical pretreatment (such as heating with dilute alkali), the cellulase hydrolysis process is gentler, reduces energy consumption and secondary pollution, and the hydrolysate is more easily utilized directly by microorganisms.

[0036] 6. The denitrification system and method of this application can control greenhouse gas emissions. The addition of plant carbon sources usually increases N2O emissions (due to the accumulation of denitrification intermediates), but the enzymatic hydrolysate of long-staple cotton can significantly improve denitrification efficiency and reduce NO3 by optimizing the C / N ratio. - -N residue reduces the potential for N2O formation. Compared to traditional monosaccharides, the carbon source released by long-staple cotton enzymatic hydrolysate is more compatible with the needs of denitrifying bacteria, reducing competition for methanogens caused by carbon source excess and further suppressing CH4 emissions.

[0037] The following will further explain the concept, specific structure and technical effects of this application in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of this application. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the constructed wetland enhanced denitrification system of this application.

[0039] Figure 2 This application includes a single-factor analysis diagram of pH value under cellulase hydrolysis conditions.

[0040] Figure 3 This is a single-factor analysis chart of enzyme dosage in the cellulase hydrolysis conditions of this application.

[0041] Figure 4 This is a single-factor analysis diagram of enzymatic hydrolysis time in the cellulase hydrolysis conditions of this application.

[0042] Figure 5 This is a 3d surface plot of the pH response under the cellulase hydrolysis conditions of this application.

[0043] Figure 6 This is a 3d surface plot of the enzyme dosage response under the cellulase hydrolysis conditions of this application.

[0044] Figure 7 This is a 3D plot of the enzymatic hydrolysis time response surface under the cellulase hydrolysis conditions of this application.

[0045] Figure 8 This is a schematic diagram of the long-staple cotton receiving pipe 34 in Embodiment 1 of this application. The left side is without long-staple cotton filling, and the right side is filled with long-staple cotton.

[0046] Figure 9 This is a graph showing the changes in nitrate and nitrogen concentrations in the wetland influent and effluent in Example 5 of this application (including Comparative Examples 1 and 2).

[0047] Figure 10 This is a graph showing the changes in ammonia nitrogen concentration in the wetland influent and effluent in Example 5 of this application (including Comparative Examples 1 and 2).

[0048] Figure 11 This is a graph showing the change in total nitrogen concentration in wetland influent and effluent in Example 5 of this application (including Comparative Examples 1 and 2). Detailed Implementation

[0049] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0050] Some exemplary embodiments of this application have been described for illustrative purposes. It should be understood that this application may be implemented in other ways not specifically shown in the accompanying drawings.

[0051] This application discloses an artificial wetland enhanced denitrification system based on the dynamic regulation of carbon sources through enzymatic hydrolysis of long-staple cotton. It mainly comprises three parts: a cellulase solution storage and transportation device 10, a nitrogen-containing wastewater storage and transportation device 20, and a wetland packing system 30. These three parts are described in detail below.

[0052] The cellulase solution storage and delivery device 10 includes a cellulase solution storage container 11 and a first peristaltic pump 12 connected via a first pipe 13. The cellulase solution storage container 11 stores a cellulase solution, which is an aqueous solution of a certain concentration prepared using cellulase. Cellulase can be purchased directly from the market or extracted or prepared using existing methods. This application is not intended to protect the method of obtaining cellulase; existing cellulases are applicable to this application. The cellulase used in the embodiments of this application was purchased, for example, from Xiasheng (Beijing) Biotechnology Development Co., Ltd.

[0053] The cellulase solution is used to hydrolyze long-staple cotton. This application has optimized the cellulase hydrolysis conditions, which are mainly divided into the following two parts.

[0054] The first part consists of a single-factor experiment, and the results are as follows: Figure 2-4As shown, when the pH value is from 6 to 8, the total reducing sugar concentration increases with increasing temperature, finally reaching its maximum value at pH 7. However, as the pH value continues to rise, the total reducing sugar concentration decreases rapidly. The reducing sugar concentration first increases and then tends to level off with increasing enzyme amount. When the enzyme amount is greater than 3 mg / L, the difference in enzymatic hydrolysis effect is not significant. The reducing sugar concentration increases with enzymatic hydrolysis time. After reaching its maximum value, further extending the enzymatic hydrolysis time does not change the total reducing sugar concentration significantly. The optimal enzymatic hydrolysis time is 18 hours.

[0055] The second part is the response surface methodology experiment, and the results are as follows: Figure 5-7 As shown, the fitting equation for this response value is obtained simultaneously:

[0056] R=2.89+0.0325A+0.1550B+0.1850C-0.0425AB+0.2125AC-0.1175BC-0.3946A 2 -0.2246B 2 -0.4096C 2 .

[0057] The model's F-value was 59.05, and P < 0.05, indicating that the model is significant. The lack-of-fit term was not significant, suggesting that the model has small experimental error and a good fit. This model can be used to analyze and predict the optimal enzymatic hydrolysis parameters for long-staple cotton. The model's coefficient of determination (R²) was 0.9907, the adjusted coefficient of determination (R²Adj) was 0.9739, and the coefficient of variation (CV%) was 2.58. Therefore, the influence of each factor on the total reducing sugar yield is in the order of enzyme amount > time > pH. The optimal experimental conditions for the enzymatic hydrolysis of long-staple cotton are pH = 7, hydrolysis time of 18 h, and cellulase concentration of 3 mg / L.

[0058] Based on the above experimental results, the preferred cellulase hydrolysis conditions for this application are as follows: the concentration of the cellulase solution is 2.5-4 mg / L, pH = 6.5-7.5, and the hydrolysis time is greater than 18 hours. This application has conducted multiple experiments under these conditions to obtain the corresponding COD value. That is, when long-staple cotton is readily available, a certain concentration of cellulase solution is used to hydrolyze long-staple cotton under the aforementioned hydrolysis conditions to obtain a long-staple cotton hydrolysate. This long-staple cotton hydrolysate has a relatively constant COD value, as shown in the table below. It should be understood that other hydrolysis conditions are also applicable to this application. The preferred conditions listed in this application do not represent the exclusion of other conditions. Although the effect may be affected, other conditions do not affect the implementation of this application.

[0059]

[0060] The first peristaltic pump 12 is used to pump the cellulase solution into the wetland packing system 30. The flow rate of the first peristaltic pump 12 can be calculated according to the following formula: Where V is the effective volume of the constructed wetland (L), a is the hydraulic retention time of the cellulase solution (h), and n is the volume ratio of the influent volume of nitrogen-containing wastewater to the volume of the cellulase solution (detailed below).

[0061] The nitrogen-containing wastewater storage and transportation device 20 includes a nitrogen-containing wastewater storage container 21 and a second peristaltic pump 22 connected via a second pipeline 23. The nitrogen-containing wastewater storage container 21 stores nitrogen-containing wastewater, which is then pumped to the wetland packing system 30 by the second peristaltic pump 22 for denitrification. The flow rate of the second peristaltic pump 22 can be calculated using the following formula: Where V is the effective volume of the constructed wetland (L), a is the hydraulic retention time of the nitrogen-containing wastewater (h), and n is the volume ratio of the influent volume of the nitrogen-containing wastewater to the volume of the cellulase solution.

[0062] In this application, the hydraulic retention time of the cellulase solution is preferably the same as that of the nitrogen-containing wastewater, and preferably ≥18h; therefore, the letter 'a' is used to represent both. The specific hydraulic retention time can be selected according to actual conditions, as long as it meets the corresponding standards for nitrogen concentrations in the final effluent.

[0063] For example, when the effective volume of the constructed wetland is 2L, the hydraulic retention time of the cellulase solution is 24h, and the volume ratio of the influent volume of nitrogenous wastewater to the volume of the cellulase solution is 1:1, the flow rates of the two peristaltic pumps are the same, which is 1 / 24 = 0.041L / h. As another example, when the effective volume of the constructed wetland is 2L, the hydraulic retention time of the cellulase solution is 24h, and the volume ratio of the influent volume of nitrogenous wastewater to the volume of the cellulase solution is 2:1, the flow rate of the first peristaltic pump 12 is 2 / (3*24) = 0.0277L / h, and the flow rate of the second peristaltic pump 22 is 0.0556L / h.

[0064] The wetland packing system 30 includes an upper packing layer 31, a main matrix layer 32, a lower packing layer 33, and long-staple cotton receiving pipes 34 located in the main matrix layer 32. It should be understood that the long-staple cotton receiving pipes 34 located in the main matrix layer 32 refer to the long-staple cotton receiving pipes 34 being primarily or mostly located within the main matrix layer 32; however, it is not excluded that some long-staple cotton receiving pipes 34 may also be located in the upper packing layer 31 and / or the lower packing layer 33. The upper end of the long-staple cotton receiving pipe 34 is connected to a first peristaltic pump 12 via a third pipe 14, so that cellulase solution is pumped to the long-staple cotton receiving pipe 34 by the first peristaltic pump 12. The upper packing layer 31 is connected to a second peristaltic pump 22 via a fourth pipe 24, so that nitrogenous wastewater is pumped to the upper packing layer 31 by the second peristaltic pump 22 and flows through the main matrix layer 32 and the lower packing layer 33.

[0065] The upper filler layer 31 is preferably composed of quartz sand with a particle size of 2-4 mm. Wetland plants 35 are planted in the upper filler layer 31; these wetland plants are commonly used in the field, such as canna lilies, calamus, water onions, and water lilies. This layer serves as a preliminary filtration and plant growth layer, trapping suspended solids and larger particulate pollutants, preventing clogging of the lower layer, and providing space for plant roots to attach, promoting the absorption of nutrients (such as nitrogen and phosphorus) and the release of oxygen, thus enhancing the activity of aerobic microorganisms. The main matrix layer 32 is preferably composed of quartz sand with a particle size of 4-6 mm. This layer is the core treatment area; a thicker quartz sand layer prolongs the hydraulic retention time, enhancing the adsorption and degradation of pollutants such as organic matter and ammonia nitrogen, and providing a habitat for facultative and anaerobic microorganisms, promoting nitrification / denitrification and the adsorption and precipitation of phosphorus. The lower packing layer 33 is preferably composed of quartz sand with a particle size of 6-8 mm. A porous water outlet pipe 36 is installed in the lower packing layer 33. The pore diameter of the porous water outlet pipe 36 is 1-2 mm, and the pore density is 8-12 pores / 10 cm³. 2 The porous outlet pipe 36 has its wall covered with 100-200 mesh nylon mesh to prevent clogging of the filler. This layer is beneficial for drainage, preventing blockages, and ensuring system stability. The coarser quartz sand improves permeability and prevents blockage at the bottom due to biofilm accumulation or particle deposition. Simultaneously, it integrates with the drainage pipe to ensure uniform water flow through the filler layer, avoiding localized water accumulation or short circuits. The preferred thickness ratio of the upper filler layer 31, the main matrix layer 32, and the lower filler layer 33 is 1:2-4:1-1.5.

[0066] like Figure 8 As shown, the long-staple cotton receiving pipe 34 is used to fill pretreated long-staple cotton. It has an open structure at the top and liquid outlet holes on the side walls and bottom. The diameter of the liquid outlet holes is 8-12 mm, and the porosity is 30-50%. The long-staple cotton receiving pipe 34 is mainly placed in the main matrix layer 32 of the wetland filler system 30. As a preferred embodiment, the angle between the axis of the long-staple cotton receiving pipe 34 and the horizontal plane is 15-75° to increase the contact area between the nitrogen-containing wastewater and the long-staple cotton receiving pipe 34. The opening at the top of the long-staple cotton receiving pipe 34 facilitates the replenishment of long-staple cotton into the pipe 34. The liquid outlet holes with a diameter of 8-12 mm not only allow enzyme molecules to diffuse efficiently to the cotton surface, but also prevent the accumulation of large molecular byproducts (such as lignin fragments) inside the pipe, effectively solving the problem of incomplete reaction. The porosity of the liquid outlet is set to 30%-50% to balance mass transfer efficiency and structural stability. High porosity (e.g., >50%) will significantly reduce the mechanical strength of the pipe, which may cause the pipe to deform or break due to the expansion of cotton after absorbing water. Low porosity (<30%) will restrict the circulation of enzyme solution, thereby forming a reaction dead zone and reducing the enzymatic hydrolysis efficiency.

[0067] The long-staple cotton used in this application is preferably derived from waste textiles, which can come from old clothes from households, household textiles, and scraps and waste materials from textile and garment factories. The system in this application can reuse waste, turning it into a valuable resource and achieving the effect of treating waste with waste. Before use, the long-staple cotton can undergo simple pretreatment such as collection, washing, drying, and cutting. The long-staple cotton, by mass fraction, has a cellulose content of 27-35%, a hemicellulose content of 12-20%, a lignin content of 20-28%, and a soluble lignin content of 8-13%. Long-staple cotton has a strong carbon release capacity. Enzymatic hydrolysis using cellulase solution is used to prepare the hydrolysate. After being added to the constructed wetland, it gradually decomposes under the action of microorganisms, releasing low-molecular-weight organic matter that can be utilized by denitrifying bacteria. This continuously and stably removes nitrogen from nitrogen-containing wastewater with a low carbon-to-nitrogen ratio, greatly improving the denitrification efficiency of the wetland system. Specifically, the cellulase solution in the cellulase solution storage container 11 is transported to the long-staple cotton receiving pipe 34 via the first pipe 13 and the third pipe 14; simultaneously, the nitrogenous wastewater in the nitrogenous wastewater storage container 21 is transported to the wetland packing system 30 via the second pipe 23 and the fourth pipe 24. After the cellulase solution in the long-staple cotton receiving pipe 34 comes into contact with the long-staple cotton, enzymatic hydrolysis occurs, yielding a long-staple cotton enzymatic hydrolysate whose main components are cellulose hydrolysis products (such as glucose, cellobiose, cellooligosaccharides, and other soluble organic matter). Since the outer wall of the long-staple cotton receiving pipe 34 has an outlet hole, the long-staple cotton enzymatic hydrolysate can flow into the constructed wetland from the outlet hole as an organic carbon source for denitrification. In the constructed wetland, microorganisms utilize the organic carbon source as an electron donor to begin heterotrophic denitrification, gradually reducing nitrate (NO3-) to nitrogen gas (N2). The long-staple cotton enzymatic hydrolysate produced in the long-staple cotton containment pipe 34 can continuously provide an organic carbon source for the constructed wetland, maintain the long-term operation of the denitrification process, and help improve the nitrogen removal efficiency of the constructed wetland system.

[0068] This application also discloses the application of an artificial wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton to treat nitrogen-containing wastewater. The application of this system can continuously release carbon sources in the artificial wetland, maintain the long-term operation of the denitrification process, and effectively improve the nitrogen removal efficiency of the wetland system and reduce the risk of eutrophication.

[0069] This application also discloses an enhanced denitrification method for constructed wetlands based on the dynamic regulation of carbon sources through enzymatic hydrolysis of long-staple cotton. This denitrification method uses the aforementioned enhanced denitrification system for constructed wetlands based on the dynamic regulation of carbon sources through enzymatic hydrolysis of long-staple cotton and mainly includes the following four steps.

[0070] Step 1: Place a cellulase solution with a concentration of 2.5-4 mg / L and a pH of 6.5-7.5 into cellulase solution storage container 11, and adjust the pH to 6.5-7.5. In this step, pH adjustment can be done using conventional acid-base solutions, preferably hydrochloric acid or sodium hydroxide solution.

[0071] Step 2: Place the nitrogen-containing wastewater into wastewater storage container 21. The nitrogen-containing wastewater in this step can be simulated wastewater or actual wastewater, and the nitrogen in the nitrogen-containing wastewater is ammonia nitrogen, nitrate nitrogen, nitrite nitrogen or a mixture thereof.

[0072] Step 3: Fill the long-staple cotton container 34 with the pretreated long-staple cotton. In this step, the amount of long-staple cotton is in excess relative to the enzyme solution. That is to say, it is sufficient to ensure that the long-staple cotton is in excess. The amount of excess can be selected according to the actual situation.

[0073] Step 4: Start the first peristaltic pump 12 and the second peristaltic pump 22. The volumes of cellulase solution and nitrogenous wastewater entering the wetland packing system 30 satisfy the following formula:

[0074]

[0075] Where C / N is the carbon-to-nitrogen ratio, that is, the total COD value to the total N concentration, C a To determine the COD value corresponding to the added cellulase solution (this value can be obtained from the table above after selecting the appropriate cellulase solution concentration), the nitrogen concentration of the cellulase solution is negligible. V b1 C represents the influent volume of nitrogen-containing wastewater (which can be measured). b1 The COD value of nitrogen-containing wastewater (which can be measured), C b2 V represents the nitrogen (total nitrogen) concentration in nitrogen-containing wastewater (which can be measured). a This refers to the volume of the added cellulase solution. As can be seen, by pre-setting the required C / N ratio (e.g., 4, 5, etc.) and selecting the appropriate cellulase solution concentration, the required volume of the cellulase solution can be calculated, which in turn allows us to obtain the volume ratio n between the influent volume of nitrogenous wastewater and the volume of the cellulase solution.

[0076] The flow rate of the first peristaltic pump 12 is: Where V is the effective volume of the constructed wetland, a is the hydraulic retention time of the cellulase solution, and n is the volume ratio of the influent volume of nitrogenous wastewater to the volume of the cellulase solution. The flow rate of the second peristaltic pump 22 is: V represents the effective volume of the constructed wetland, a represents the hydraulic retention time of the nitrogen-containing wastewater, and n represents the volume ratio of the influent volume of the nitrogen-containing wastewater to the volume of the cellulase solution. The hydraulic retention time of the nitrogen-containing wastewater or the hydraulic retention time of the cellulase solution are the same, preferably ≥18h.

[0077] Example 1: Construction of an Enhanced Denitrification System for Constructed Wetlands Based on Enzymatic Hydrolysis of Long-Staple Cotton and Dynamic Regulation of Carbon Sources

[0078] 1. Constructing a wetland filler system

[0079] In this embodiment, the constructed wetland adopts a downflow. The wetland filler system 30 is filled from top to bottom with an upper filler layer 31, a main matrix layer 32, and a lower filler layer 33. The upper filler layer 31 includes quartz sand with a thickness of 10 cm and a particle size of 2 mm. The main matrix layer 32 includes quartz sand with a thickness of 20 cm and a particle size of 4 mm. The lower filler layer 33 includes quartz sand with a thickness of 10 cm and a particle size of 6 mm. The upper filler layer 31 is planted with wetland plants 35, canna lilies.

[0080] During the filling of the main matrix layer 32, a long-staple cotton receiving pipe 34 is inserted. The long-staple cotton receiving pipe 34 has an open top structure, and liquid outlet holes with a diameter of 8 mm and a porosity of 30% are opened on the side wall and bottom. The axis of the long-staple cotton receiving pipe 34 makes an angle of 15° with the horizontal plane. In this embodiment, the long-staple cotton comes from waste clothing. The recycled waste clothing is collected, washed, dried, and cut, and then filled into the long-staple cotton receiving pipe 34 after simple pretreatment.

[0081] A porous water outlet pipe 36 is installed in the lower packing layer 33. The porous water outlet pipe 36 has a pore diameter of 1 mm and a pore density of 8 pores / 10 cm. 2 The pipe wall is covered with 100-mesh nylon mesh.

[0082] 2. Construct a cellulase solution storage and transportation device 10 and a nitrogen-containing wastewater storage and transportation device 20.

[0083] Cellulase solution storage container 11 is connected to the first peristaltic pump 12 via the first pipe 13, nitrogen-containing wastewater storage container 21 is connected to the second peristaltic pump 22 via the second pipe 23, the upper end of long-staple cotton receiving pipe 34 is connected to the first peristaltic pump 12 via the third pipe 14, and the upper packing layer 31 is connected to the second peristaltic pump 22 via the fourth pipe 24.

[0084] 3. Operate the denitrification system

[0085] The inoculated sludge was taken from the secondary sedimentation tank of the Songjiang Wastewater Treatment Plant in Shanghai and sealed for 2 days to become anaerobic activated sludge. A small amount of diluted sludge suspension was added to the prepared nitrate wastewater, along with a fixed amount of nutrients (the composition of which is shown in the table below). The nutrient-to-influent volume ratio was 1:1000. After thorough mixing, the mixture was added to the constructed wetland device to acclimate the microorganisms. The total acclimatization period was 30 days, during which the water was changed every three days to ensure sufficient carbon source for normal microbial growth. After 30 days, yellowish-brown sludge flocs were observed forming on the surface of quartz sand and elemental sulfur particles in the constructed wetland, occasionally accompanied by small bubbles. At this point, the biofilm formation in the constructed wetland was considered successful. The plant then entered the trial operation phase, and after the effluent indicators stabilized, it entered the formal experimental phase.

[0086]

[0087] Example 2: Construction of an Enhanced Denitrification System for Constructed Wetlands Based on Enzymatic Hydrolysis of Long-Staple Cotton and Dynamic Regulation of Carbon Sources (Part 2)

[0088] 1. Constructing a wetland filler system

[0089] In this embodiment, the constructed wetland adopts a downflow. The wetland filler system 30 is filled from top to bottom with an upper filler layer 31, a main matrix layer 32, and a lower filler layer 33. The upper filler layer 31 includes quartz sand with a thickness of 10 cm and a particle size of 4 mm. The main matrix layer 32 includes quartz sand with a thickness of 40 cm and a particle size of 6 mm. The lower filler layer 33 includes quartz sand with a thickness of 15 cm and a particle size of 8 mm. The upper filler layer 31 is planted with wetland plants 35, sweet flag.

[0090] During the filling of the main matrix layer 32, a long-staple cotton receiving pipe 34 is inserted. The long-staple cotton receiving pipe 34 has an open top structure, and liquid outlet holes with a diameter of 12mm and a porosity of 50% are opened on the side wall and bottom. The axis of the long-staple cotton receiving pipe 34 makes an angle of 75° with the horizontal plane. In this embodiment, the long-staple cotton comes from waste clothing. The recycled waste clothing is collected, washed, dried, and cut, and then filled into the long-staple cotton receiving pipe 34 after simple pretreatment.

[0091] A porous water outlet pipe 36 is installed in the lower packing layer 33. The porous water outlet pipe 36 has a pore diameter of 2 mm and a pore density of 12 pores / 10 cm. 2 The pipe wall is covered with 200-mesh nylon mesh.

[0092] 2. Construct a cellulase solution storage and transportation device 10 and a nitrogen-containing wastewater storage and transportation device 20.

[0093] Cellulase solution storage container 11 is connected to the first peristaltic pump 12 via the first pipe 13, nitrogen-containing wastewater storage container 21 is connected to the second peristaltic pump 22 via the second pipe 23, the upper end of long-staple cotton receiving pipe 34 is connected to the first peristaltic pump 12 via the third pipe 14, and the upper packing layer 31 is connected to the second peristaltic pump 22 via the fourth pipe 24.

[0094] 3. Operate the denitrification system

[0095] The inoculated sludge was taken from the secondary sedimentation tank of the Songjiang Wastewater Treatment Plant in Shanghai and sealed for 5 days to become anaerobic activated sludge. A small amount of diluted sludge suspension was added to the prepared nitrate wastewater, along with a fixed amount of nutrients (same as in Example 1). The nutrient-to-influent volume ratio was 1:1000. After thorough mixing, the mixture was added to the constructed wetland device to acclimate the microorganisms. The total acclimatization period was 30 days, during which the water was changed every three days to ensure sufficient carbon source for normal microbial growth. After 30 days, yellowish-brown sludge flocs were observed forming on the surface of quartz sand and elemental sulfur particles in the constructed wetland, occasionally accompanied by small bubbles. At this point, the biofilm formation in the constructed wetland was considered successful. Then, the trial operation phase began, and the formal experimental phase commenced once the effluent indicators stabilized.

[0096] Example 3: Construction of an Enhanced Denitrification System for Constructed Wetlands Based on Enzymatic Hydrolysis of Long-Staple Cotton and Dynamic Regulation of Carbon Sources (Part 3)

[0097] 1. Constructing a wetland filler system

[0098] In this embodiment, the constructed wetland adopts a downflow. The wetland filler system 30 is filled from top to bottom with an upper filler layer 31, a main matrix layer 32, and a lower filler layer 33. The upper filler layer 31 includes quartz sand with a thickness of 10 cm and a particle size of 3 mm. The main matrix layer 32 includes quartz sand with a thickness of 25 cm and a particle size of 5 mm. The lower filler layer 33 includes quartz sand with a thickness of 10 cm and a particle size of 7 mm. Wetland plants 35, water onions, are planted in the upper filler layer 31.

[0099] During the filling of the main matrix layer 32, a long-staple cotton receiving pipe 34 is inserted. The long-staple cotton receiving pipe 34 has an open top structure, and liquid outlet holes with a diameter of 10 mm and a porosity of 40% are opened on the side wall and bottom. The axis of the long-staple cotton receiving pipe 34 makes an angle of 45° with the horizontal plane. In this embodiment, the long-staple cotton comes from waste clothing. The recycled waste clothing is collected, washed, dried, and cut, and then filled into the long-staple cotton receiving pipe 34 after simple pretreatment.

[0100] A porous water outlet pipe 36 is installed in the lower packing layer 33. The porous water outlet pipe 36 has a pore diameter of 1.5 mm and a pore density of 10 pores / 10 cm. 2 The pipe wall is covered with 160-mesh nylon mesh.

[0101] 2. Construct a cellulase solution storage and transportation device 10 and a nitrogen-containing wastewater storage and transportation device 20.

[0102] Cellulase solution storage container 11 is connected to the first peristaltic pump 12 via the first pipe 13, nitrogen-containing wastewater storage container 21 is connected to the second peristaltic pump 22 via the second pipe 23, the upper end of long-staple cotton receiving pipe 34 is connected to the first peristaltic pump 12 via the third pipe 14, and the upper packing layer 31 is connected to the second peristaltic pump 22 via the fourth pipe 24.

[0103] 3. Operate the denitrification system

[0104] The inoculated sludge was taken from the secondary sedimentation tank of the Songjiang Wastewater Treatment Plant in Shanghai and sealed for 3 days to become anaerobic activated sludge. A small amount of diluted sludge suspension was added to the prepared nitrate wastewater, along with a fixed amount of nutrients (same as in Example 1). The nutrient-to-influent volume ratio was 1:1000. After thorough mixing, the mixture was added to the constructed wetland device to acclimate the microorganisms. The total acclimatization period was 30 days, during which the water was changed every three days to ensure sufficient carbon source for normal microbial growth. After 30 days, yellowish-brown sludge flocs were observed forming on the surface of quartz sand and elemental sulfur particles in the constructed wetland, occasionally accompanied by small bubbles. At this point, the biofilm formation in the constructed wetland was considered successful. Then, the trial operation phase began, and the formal experimental phase commenced once the effluent indicators stabilized.

[0105] Example 4: Construction of an Enhanced Denitrification System for Constructed Wetlands Based on Enzymatic Hydrolysis of Long-Staple Cotton and Dynamic Regulation of Carbon Sources (Part 4)

[0106] 1. Constructing a wetland filler system

[0107] In this embodiment, the constructed wetland adopts a downflow. The wetland filler system 30 is filled from top to bottom with an upper filler layer 31, a main matrix layer 32, and a lower filler layer 33. The upper filler layer 31 includes quartz sand with a thickness of 10 cm and a particle size of 2 mm. The main matrix layer 32 includes quartz sand with a thickness of 20 cm and a particle size of 4 mm. The lower filler layer 33 includes quartz sand with a thickness of 10 cm and a particle size of 6 mm. The upper filler layer 31 is planted with wetland plants 35, water lilies.

[0108] During the filling of the main matrix layer 32, a long-staple cotton receiving pipe 34 is inserted. The long-staple cotton receiving pipe 34 has an open top structure, and liquid outlet holes with a diameter of 10 mm and a porosity of 50% are opened on the side wall and bottom. The axis of the long-staple cotton receiving pipe 34 makes an angle of 30° with the horizontal plane. In this embodiment, the long-staple cotton comes from waste clothing. The recycled waste clothing is collected, washed, dried, and cut, and then filled into the long-staple cotton receiving pipe 34 after simple pretreatment.

[0109] A porous water outlet pipe 36 is installed in the lower packing layer 33. The porous water outlet pipe 36 has a pore diameter of 2 mm and a pore density of 12 pores / 10 cm. 2 The pipe wall is covered with 200-mesh nylon mesh.

[0110] 2. Construct a cellulase solution storage and transportation device 10 and a nitrogen-containing wastewater storage and transportation device 20.

[0111] Cellulase solution storage container 11 is connected to the first peristaltic pump 12 via the first pipe 13, nitrogen-containing wastewater storage container 21 is connected to the second peristaltic pump 22 via the second pipe 23, the upper end of long-staple cotton receiving pipe 34 is connected to the first peristaltic pump 12 via the third pipe 14, and the upper packing layer 31 is connected to the second peristaltic pump 22 via the fourth pipe 24.

[0112] 3. Operate the denitrification system

[0113] The inoculated sludge was taken from the secondary sedimentation tank of the Songjiang Wastewater Treatment Plant in Shanghai and sealed for 5 days to become anaerobic activated sludge. A small amount of diluted sludge suspension was added to the prepared nitrate wastewater, along with a fixed amount of nutrients (same as in Example 1). The nutrient-to-influent volume ratio was 1:1000. After thorough mixing, the mixture was added to the constructed wetland device to acclimate the microorganisms. The total acclimatization period was 30 days, during which the water was changed every three days to ensure sufficient carbon source for normal microbial growth. After 30 days, yellowish-brown sludge flocs were observed forming on the surface of quartz sand and elemental sulfur particles in the constructed wetland, occasionally accompanied by small bubbles. At this point, the biofilm formation in the constructed wetland was considered successful. Then, the trial operation phase began, and the formal experimental phase commenced once the effluent indicators stabilized.

[0114] Example 5: Treatment of Nitrogen-Containing Wastewater

[0115] This embodiment uses the constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton and dynamically regulated carbon source constructed in Example 1. The effective volume of the wetland packing system in this system is 2L. This embodiment is divided into four stages: Stage 1 (days 1-20): C / N = 1; Stage 2 (days 21-40): C / N = 2; Stage 3 (days 41-60): C / N = 3; Stage 4 (days 61-80): C / N = 4. Regarding the calculation of the cellulase solution volume, Stage 2 is used as an example. 1L (V b1 The COD value is 30 mg / L (C b1 The total nitrogen concentration was 40 mg / L (C b2 Nitrogenous wastewater was added to wastewater storage container 21. The concentration of cellulase solution used was 3 mg / L, and the pH was adjusted to 7. According to the table above, the corresponding COD value was 117.12 mg / L. The volume V of the cellulase solution was then calculated using the following formula. a It is 0.43L.

[0116]

[0117] Therefore, 0.43 L of 3 mg / L cellulase solution was added to cellulase solution storage container 11, and the pH was adjusted to 7. Excess pretreated long-staple cotton was filled into the long-staple cotton receiving pipe (34), and then the first peristaltic pump 12 and the second peristaltic pump 22 were started. The hydraulic retention time of the nitrogen-containing wastewater was set to 24 h. The flow rates of the first peristaltic pump 12 and the second peristaltic pump 22 were calculated by the following formula (where n = volume ratio of nitrogen-containing wastewater influent to cellulase solution = 1 / 0.43 = 2.33):

[0118] The flow rate of the first peristaltic pump 12 is:

[0119] The flow rate of the second peristaltic pump 22 is:

[0120] In this embodiment, the hydraulic retention time is set to 24 hours (this hydraulic retention time will be adjusted according to actual conditions). This means that every 24 hours, new nitrogen-containing wastewater with potentially different concentrations of ammonia nitrogen, nitrate nitrogen, and COD values ​​will enter the wetland system. According to the above formula, a suitable C / N ratio can be selected before each influent flow, and a cellulase solution of any concentration within the scope of this application can be chosen. The volume of the corresponding cellulase solution and the flow rates of the first peristaltic pump 12 and the second peristaltic pump 22 can then be calculated. Therefore, the scheme of this application achieves the effect of dynamically adjusting the carbon source.

[0121] Comparative Example 1

[0122] Comparative Example 1 is similar to Example 5, except that the cellulase solution and long-staple cotton are replaced with glucose at the same C / N ratio.

[0123] Comparative Example 2

[0124] Comparative Example 2 is similar to Example 5, except that no cellulase solution is added.

[0125] The nitrogen treatment results of Example 5, Comparative Example 1, and Comparative Example 2 are as follows: Figure 9-11 And as shown in the table below, the table shows the average concentration or average removal rate for the four stages.

[0126]

[0127] In the first stage, no additional carbon source was added to Example 5, Comparative Example 1, and Comparative Example 2, and the theoretical C / N ratio was 1.0. In the second, third, and fourth stages, additional carbon sources were added to Example 5 and Comparative Example 1 to achieve theoretical C / N ratios of 2.0, 3.0, and 4.0, respectively, while Comparative Example 2 only added the same weight of long-staple cotton as Example 5, without adding any additional carbon source.

[0128] The experimental results show that the total nitrogen removal rate of Comparative Example 1 and Example 5 significantly increased with the increase of carbon source addition (C / N ratios of 2, 3, and 4), and was significantly better than that of Comparative Example 2. Specifically, when the C / N ratio was 4, the total nitrogen removal rates of Comparative Example 1 and Example 5 reached 99.5% and 99.1%, respectively, while the total nitrogen removal rate of Example 2 without the addition of a carbon source was only 51.2%. Therefore, the cellulase solution and long-staple cotton of this application achieved a similar effect to glucose in providing a carbon source.

[0129] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. An artificial wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton and dynamic regulation of carbon source, characterized in that, include: A cellulase solution storage and delivery device (10) includes a cellulase solution storage container (11) and a first peristaltic pump (12) connected by a first pipe (13). The cellulase solution storage container (11) is used to store a cellulase solution with a concentration of 2.5-4 mg / L and a pH of 6.5-7.

5. The nitrogen-containing wastewater storage and transportation device (20) includes a nitrogen-containing wastewater storage container (21) and a second peristaltic pump (22) connected by a second pipeline (23); The wetland filling system (30) includes an upper filling layer (31), a main matrix layer (32), a lower filling layer (33), and a long-staple cotton receiving pipe (34) located in the main matrix layer (32). The upper end of the long-staple cotton receiving pipe (34) is connected to a first peristaltic pump (12) through a third pipe (14). The upper filling layer (31) is connected to a second peristaltic pump (22) through a fourth pipe (24). The long-staple cotton receiving pipe (34) is used to fill pretreated long-staple cotton. The long-staple cotton receiving pipe (34) has an open structure at the upper end. The side wall and bottom of the long-staple cotton receiving pipe (34) are provided with liquid outlet holes. The diameter of the liquid outlet holes is 8-12 mm and the porosity is 30-50%.

2. The constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources as described in claim 1, characterized in that, The long-staple cotton comes from waste textiles.

3. The constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources as described in claim 1, characterized in that, The angle between the axis of the long-staple cotton receiving pipe (34) and the horizontal plane is 15-75°.

4. The constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources as described in claim 1, characterized in that, The upper filler layer (31) is planted with wetland plants (35); and / or The lower packing layer (33) is equipped with a porous water outlet pipe (36), the porous water outlet pipe (36) has a pore diameter of 1-2 mm and a pore density of 8-12 pores / 10 cm², and the pipe wall of the porous water outlet pipe (36) is covered with 100-200 mesh nylon mesh.

5. The constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources as described in claim 1, characterized in that, The upper filler layer (31) comprises quartz sand with a particle size of 2-4 mm, the main matrix layer (32) comprises quartz sand with a particle size of 4-6 mm, and the lower filler layer (33) comprises quartz sand with a particle size of 6-8 mm.

6. The constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources as described in claim 5, characterized in that, The thickness ratio of the upper filler layer (31), the main matrix layer (32) and the lower filler layer (33) is 1:2-4:1-1.

5.

7. The application of the constructed wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton and dynamically regulated carbon source as described in claim 1 in the treatment of nitrogen-containing wastewater.

8. A method for enhanced nitrogen removal in constructed wetlands based on enzymatic hydrolysis of long-staple cotton and dynamic regulation of carbon sources, characterized in that, The denitrification method uses an artificial wetland enhanced denitrification system based on enzymatic hydrolysis of long-staple cotton with dynamically regulated carbon sources, as described in any one of claims 1-6. The denitrification method includes the following steps: S1. Place a cellulase solution with a concentration of 2.5-4 mg / L into a cellulase solution storage container (11) and adjust the pH to 6.5-7.5; S2. Place the nitrogen-containing wastewater in the wastewater storage container (21); S3. Fill the pretreated long-staple cotton into the long-staple cotton receiving pipe (34). S4. Start the first peristaltic pump (12) and the second peristaltic pump (22); The volumes of cellulase solution and nitrogen-containing wastewater entering the wetland packing system satisfy the following formula: Among them, C a V represents the COD value corresponding to the cellulase solution. a V represents the volume of cellulase solution added. b1 C represents the influent volume of nitrogen-containing wastewater. b1 The COD value of nitrogen-containing wastewater, C b2 The nitrogen concentration of the nitrogen-containing wastewater; and, The flow rate of the first peristaltic pump (12) is: ; The flow rate of the second peristaltic pump (22) is: ; V is the effective volume of the constructed wetland, a is the hydraulic retention time of nitrogen-containing wastewater or the hydraulic retention time of cellulase solution, and n is the volume ratio of nitrogen-containing wastewater to cellulase solution.

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