Constructed wetland enhanced denitrification system for dynamically regulating and controlling carbon source based on long stapled cotton enzymolysis as well as application and method of constructed wetland enhanced denitrification system

Abstract

The invention discloses a constructed wetland enhanced denitrification system capable of dynamically regulating and controlling a carbon source based on long stapled cotton enzymolysis as well as application and a method thereof, and the system comprises a cellulase solution storage and conveying device which comprises a cellulase solution storage container and a first peristaltic pump which are connected through a first pipeline; the nitrogenous wastewater storage and conveying device comprises a nitrogenous wastewater storage container and a second peristaltic pump which are 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 stapled cotton containing pipeline located on the main substrate layer, the upper end of the long stapled cotton containing pipeline is connected to a first peristaltic pump through a third pipeline, and the upper filler layer is connected to a second peristaltic pump through a fourth pipeline. According to the preparation method, the long stapled cotton is subjected to enzymolysis through cellulase to serve as the carbon source, the limitation that when natural cellulose serves as the carbon source, the release efficiency is low, and the liquid or biodegradable polymer carbon source is high in adding cost is overcome, the long stapled cotton comes from waste textiles, and waste is turned into wealth.

Description

Technical Field

[0001] The present application relates to the technical field of water pollution treatment, and more specifically, to an artificial wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis with dynamically regulated carbon sources, and its application and method. Background Art

[0002] At present, although a large number of slightly polluted water bodies (including receiving rivers, sewage treatment plant tail water, urban surface runoff and agricultural non-point source drainage, etc.) meet the limit values ​​of the "Pollutant Discharge Standards for Urban Wastewater Treatment Plants", their core indicators still generally exceed the requirements of Class V water bodies in the "Surface Water Environmental Quality Standards". This type of water body has two typical characteristics: a large amount of water and a structural lack of carbon sources, which are specifically manifested in the lack of bioavailable organic matter and an imbalance in the carbon-nitrogen ratio. In governance practice, the mainstream technology relies on the direct addition of liquid carbon sources to achieve deep denitrification. Although this method has the advantages of low investment and convenient operation in short-term operation and maintenance, its long-term sustainability has significant defects, including high operating costs caused by the continuous consumption of carbon sources, pressure to dispose of excessive residual sludge, and a surge in greenhouse gas emissions.

[0003] Solid-state denitrification technologies for the treatment of nitrogen-containing wastewater with a low carbon-to-nitrogen ratio are primarily developed based on natural solid-phase carbon sources or synthetic carbon sources. Currently, the most studied natural solid-phase carbon sources are primarily inexpensive and readily available agricultural waste, such as sawdust, straw, rice husks, corn cobs, and peanut shells. However, because the cellulose and hemicellulose in litter lose carbon during long-term weathering and decomposition in the natural environment, the initial total carbon content of the hydrolyzate is often insufficient to meet the demand for sustained carbon release, which can easily lead to a decrease in subsequent denitrification efficiency. Directly using fresh plants as a supplementary carbon source presents new challenges: on the one hand, the high pigment content of fresh green plant tissues continuously dissolves during immersion in water, causing not only a significant increase in water color but also an increase in the denitrification system's processing load due to their high nitrogen content. On the other hand, the inherent carbon release characteristics of plant materials exhibit distinct phased differences—carbon release explodes in the early stages, while rapidly declining in the middle and late stages, resulting in significant fluctuations in carbon source supply.

[0004] In view of the above technical problems, technicians in this field are committed to studying a new type of high-efficiency denitrification system suitable for nitrogen-containing wastewater with a low carbon-nitrogen ratio. Summary of the Invention

[0005] Based on the above shortcomings of the prior art, the purpose of this application is to use cellulase to efficiently degrade cellulose into oligosaccharides or monosaccharides as organic carbon sources to solve the problem of low carbon-nitrogen ratio in traditional artificial wetlands, so as to provide an artificial wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis with dynamic regulation of carbon sources and its application and method.

[0006] In artificial wetlands, denitrification is mainly achieved through two processes: autotrophic denitrification and heterotrophic denitrification. Heterotrophic denitrification is a process in which denitrifying bacteria use organic carbon sources as electron donors under anoxic conditions to gradually reduce nitrate (NO3-) to nitrogen gas (N2). 12 O6) as an example, the chemical reaction formula of 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 due to its high cellulose content (>90%), but its natural lattice structure limits its bioavailability. Cellulase can efficiently degrade cellulose into oligosaccharides and monosaccharides, which serve as an organic carbon source for denitrification in constructed wetlands, thereby ensuring the efficient denitrification capacity of constructed wetlands in treating low-C / N wastewater.

[0009] The main components of long-staple cotton enzymatic hydrolysate are cellulose hydrolysis products (such as glucose, cellobiose, cellooligosaccharides and other soluble organic matter). As a carbon source for artificial wetlands, it has the characteristics of wide sources, low cost and easy degradation. It is particularly suitable for continuous release of carbon sources in artificial wetlands to maintain the long-term operation of the denitrification process. Its application can effectively improve the wetland system's nitrate removal efficiency 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 the first aspect, the present application provides an artificial wetland enhanced denitrification system with dynamically regulated carbon sources based on long-staple cotton enzymatic hydrolysis, comprising: a cellulase solution storage and delivery device, comprising a cellulase solution storage container and a first peristaltic pump connected by a first pipe; a nitrogen-containing wastewater storage and delivery device, comprising a nitrogen-containing wastewater storage container and a second peristaltic pump connected by a second pipe; a wetland filler system, comprising an upper filler layer, a main matrix layer, a lower filler layer and a long-staple cotton containing pipe located in the main matrix layer, the upper end of the long-staple cotton containing pipe being connected to the first peristaltic pump via a third pipe, and the upper filler layer being connected to the second peristaltic pump via a fourth pipe.

[0011] Preferably, the long-staple cotton containing pipe is an upper-end open structure, and liquid outlet holes are opened on the side walls and bottom of the long-staple cotton containing pipe. The aperture of the liquid outlet holes is 8-12 mm, and the porosity is 30-50%.

[0012] Preferably, the long-staple cotton receiving pipe is used to be filled with pre-treated long-staple cotton, and the long-staple cotton comes from waste textiles.

[0013] Preferably, the angle between the axis of the long-staple cotton containing 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, wetland plants are planted in the upper packing layer; and / or a porous water outlet pipe is installed in the lower packing layer, the pore diameter of the porous water outlet pipe is 1-2 mm, and the pore density is 8-12 holes / 10 cm 2 The wall of the porous water outlet pipe is covered with a 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] In the second aspect, the present application provides an application of an artificial wetland enhanced denitrification system based on dynamic regulation of carbon sources by enzymatic hydrolysis of long-staple cotton in the treatment of nitrogen-containing wastewater.

[0019] In a third aspect, the present application provides a method for enhanced denitrification in an artificial wetland based on the dynamic regulation of carbon sources by enzymatic hydrolysis of long-staple cotton. The denitrification method uses an artificial wetland enhanced denitrification system based on the dynamic regulation of carbon sources by enzymatic hydrolysis of long-staple cotton. The denitrification method comprises the following steps:

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

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

[0022] S3, filling the long-staple cotton containing pipe with pretreated long-staple cotton;

[0023] S3, starting the first peristaltic pump and the second peristaltic pump;

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

[0025]

[0026] Among them, C / N is the carbon-nitrogen ratio, C a is the COD value of the cellulase solution measured before addition, V a is the volume of cellulase solution added, V b1is the volume of nitrogen-containing wastewater inflow, C b1 is the COD value of nitrogen-containing wastewater, C b2 is the nitrogen concentration of the nitrogenous 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 artificial wetland, a is the hydraulic retention time of the nitrogen-containing wastewater or the hydraulic retention time of the cellulase solution, and n is the volume ratio of the nitrogen-containing wastewater to the cellulase solution.

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

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

[0032] 2. The denitrification system described in this application utilizes a novel artificial wetland, utilizing cellulase hydrolyzate as a carbon source for denitrification. This system, combined with the root activity of wetland plants, creates an effective ecological reaction environment, promoting the removal of nitrate nitrogen. This system offers the advantages of low energy consumption, ease of operation, efficient carbon source utilization, and waste resource utilization. Furthermore, it can achieve efficient nitrogen removal from low-carbon wastewater, resulting in clean, efficient, and environmentally friendly results.

[0033] 3. The long-staple cotton of this application comes from waste textiles, which can come from waste clothing, household waste textiles, scraps and waste materials from the production process of textile factories and garment factories, etc., achieving the effect of waste reuse, turning waste into treasure and treating waste with waste.

[0034] 4. The denitrification system and method of the present application utilize carbon sources with high efficiency and stability. Traditional liquid carbon sources (such as glucose and sodium acetate) are easily consumed quickly, require frequent addition, and are prone to secondary pollution. Long-staple cotton fibers have the characteristics of high cellulose content and dense structure. After hydrolysis by cellulase, they can release a large amount of soluble organic carbon (such as glucose), providing an efficient electron donor for denitrifying bacteria and significantly improving denitrification efficiency. The long-staple cotton hydrolyzate can form a slow-release system through enzymatic control, 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 hydrolyzate contains no additional chemical additives, avoiding the toxic risks of traditional carbon sources (such as methanol) and meeting the sustainable needs of ecological restoration. Compared to plant carbon sources such as corn cobs that require physical or chemical pretreatment (such as heating with dilute alkali), the cellulase hydrolysis process is more gentle, reducing energy consumption and secondary pollution, and the hydrolyzate is more easily directly utilized by microorganisms.

[0036] 6. The denitrification system and method of the present 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 long-staple cotton enzymatic hydrolysate can significantly improve the denitrification efficiency and reduce NO3 by optimizing the C / N ratio. - -N residues, thereby reducing the potential for N2O production. Compared to traditional monosaccharides, the carbon source released by long-staple cotton enzymatic hydrolysate is more closely aligned with the needs of denitrifying bacteria, reducing competition for methanogenesis caused by excess carbon sources and further suppressing CH4 emissions.

[0037] The concept, specific structure and technical effects of this application will be further explained below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural schematic diagram of the artificial wetland enhanced denitrification system of this application.

[0039] Figure 2 Single factor analysis diagram of pH value in the cellulase hydrolysis conditions of this application.

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

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

[0042] Figure 5 This is a 3D graph of the pH response surface in the cellulase hydrolysis conditions of this application.

[0043] Figure 6 This is a 3D graph of the response surface of enzyme dosage in the cellulase hydrolysis conditions of this application.

[0044] Figure 7 It is a 3D graph of the enzymatic hydrolysis time response surface in the cellulase enzymatic hydrolysis conditions of this application.

[0045] Figure 8 This is a schematic diagram of the long-staple cotton containing pipe 34 in Example 1 of the present application, the left side is not filled with long-staple cotton, and the right side is filled with long-staple cotton.

[0046] Figure 9 This is a graph showing changes in nitrate-nitrogen concentrations in the inlet and outlet water of the wetland in Example 5 of the present application (including Comparative Examples 1 and 2).

[0047] Figure 10 This is a graph showing changes in ammonia nitrogen concentrations in the inlet and outlet water of the wetland in Example 5 of the present application (including Comparative Examples 1 and 2).

[0048] Figure 11 This is a graph showing changes in total nitrogen concentration in the inlet and outlet water of the wetland in Example 5 of the present application (including Comparative Examples 1 and 2). DETAILED DESCRIPTION

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

[0050] Some exemplary embodiments of the present application are described for the purpose of illustration. It should be understood that the present application may be implemented in other ways not specifically shown in the drawings.

[0051] This application discloses a constructed wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis and dynamically controlled carbon sources. The system primarily comprises three components: a cellulase solution storage and delivery device 10, a nitrogen-containing wastewater storage and delivery device 20, and a wetland filler system 30. These three components 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 by a first pipe 13. The cellulase solution storage container 11 stores a cellulase solution, which is an aqueous solution with a certain concentration configured using cellulase. Cellulase can be purchased directly from the market or extracted or prepared by existing methods. This application is not intended to protect the method of obtaining cellulase, and all existing cellulases are applicable to this application. The cellulase used in the embodiments of this application is purchased, for example, from Xiasheng (Beijing) Biotechnology Development Co., Ltd.

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

[0054] The first part is to conduct a single factor variable test. The results are as follows Figure 2-4As shown in the figure, when the pH value is from 6 to 8, the total reducing sugar concentration increases with the increase of temperature, and finally reaches the maximum value at 7, but as the pH value continues to rise, the total reducing sugar concentration decreases rapidly; the reducing sugar concentration will first increase and then tend to be flat with the increase of enzyme amount, and the enzymatic hydrolysis effect is not much different when the enzyme amount is greater than 3 mg / l; the reducing sugar concentration will increase with the enzymatic hydrolysis time. After reaching the maximum value, the total reducing sugar concentration remains basically unchanged when the enzymatic hydrolysis time is continued to be extended. The optimal enzymatic hydrolysis time is 18h.

[0055] The second part is the response surface analysis test, and the results are as follows Figure 5-7 As shown, the fitting equation of the response value is obtained at the same time:

[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, with a P value of <0.05, indicating that the model was significant. The lack-of-fit term was insignificant, indicating that the model had a low 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 various factors on total reducing sugar yield was in the order of enzyme dosage > time > pH. The optimal experimental conditions for enzymatic hydrolysis of long-staple cotton were pH 7, a hydrolysis time of 18 hours, and a cellulase concentration of 3 mg / L.

[0058] Combined with the above test results, the preferred cellulose enzymatic hydrolysis conditions of this application are as follows: the concentration of the cellulase solution is 2.5-4 mg / L, pH = 6.5-7.5, and the enzymatic hydrolysis time is greater than 18h. This application has conducted multiple experiments under these conditions and obtained the corresponding COD value, that is, when there is sufficient long-staple cotton, a certain concentration of cellulase solution is used to enzymatically hydrolyze the long-staple cotton under the above-mentioned enzymatic hydrolysis conditions to obtain a long-staple cotton enzymatic hydrolyzate, which has a relatively constant COD value, as shown in the following table. It should be understood that other enzymatic hydrolysis conditions are also applicable to this application. This application lists the preferred conditions, which does not mean that other conditions are excluded. Although the effect will 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 to the wetland filler system 30. The flow rate of the first peristaltic pump 12 can be calculated according to the following formula: Wherein, 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 (described in detail below).

[0061] The nitrogen-containing wastewater storage and delivery device 20 includes a nitrogen-containing wastewater storage container 21 and a second peristaltic pump 22 connected by a second pipe 23. The nitrogen-containing wastewater storage container 21 is used to store nitrogen-containing wastewater, which is pumped to the wetland filler system 30 for denitrification by the second peristaltic pump 22. The flow rate of the second peristaltic pump 22 can be calculated according to the following formula: Wherein, V is the effective volume of the constructed wetland (L), a is the hydraulic retention time of the nitrogenous wastewater (h), and n is the volume ratio of the influent volume of the nitrogenous 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 is preferably ≥18 hours, so both are represented by the letter "a". The specific hydraulic retention time can be selected according to actual conditions, as long as the nitrogen concentration of the final effluent meets the corresponding standards.

[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 the nitrogen-containing wastewater to the volume of the cellulase solution is 1:1, the two peristaltic pumps have the same flow rate, 1 / 24 = 0.041L / h. For 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 the nitrogen-containing 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 filler system 30 includes an upper filler layer 31, a main matrix layer 32, a lower filler layer 33, and a long-staple cotton containment conduit 34 located in the main matrix layer 32. It should be understood that the long-staple cotton containment conduit 34 located in the main matrix layer 32 here refers to the long-staple cotton containment conduit 34 being primarily, or mostly, located in the main matrix layer 32, although it is not excluded that a portion of the long-staple cotton containment conduit 34 may be located in the upper filler layer 31 and / or the lower filler layer 33. The upper end of the long-staple cotton containment conduit 34 is connected to the first peristaltic pump 12 via the third conduit 14, so that the cellulase solution is pumped into the long-staple cotton containment conduit 34 via the first peristaltic pump 12. The upper filler layer 31 is connected to the second peristaltic pump 22 via the fourth conduit 24, so that the nitrogen-containing wastewater is pumped into the upper filler layer 31 by the second peristaltic pump 22 and flows through the main matrix layer 32 and the lower filler layer 33.

[0065] The upper packing layer 31 is preferably quartz sand with a particle size of 2-4 mm. Wetland plants 35 are planted in the upper packing layer 31. The wetland plants are commonly used in this field, such as canna, calamus, water plantain, water lily, etc. This layer is used for preliminary filtration and plant growth. It can intercept suspended matter and larger particulate pollutants to prevent clogging of the lower layer, and provide space for plant roots to attach, promote plant absorption of nutrients (such as nitrogen and phosphorus) and release oxygen, and enhance the activity of aerobic microorganisms. The main matrix layer 32 is preferably quartz sand with a particle size of 4-6 mm. This layer is the core treatment area. The thicker quartz sand layer prolongs the hydraulic retention time, enhances the adsorption and degradation of pollutants such as organic matter and ammonia nitrogen, and provides a habitat for facultative and anaerobic microorganisms, promoting nitrification / denitrification and phosphorus adsorption and precipitation. The lower packing layer 33 is preferably made 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 size of the porous water outlet pipe 36 is 1-2 mm and the pore density is 8-12 holes / 10 cm 2 The porous outlet pipe 36 is coated with a 100-200 mesh nylon mesh to prevent clogging. This layer helps prevent drainage blockage and maintain system stability. Coarse quartz sand improves water permeability and prevents clogging at the bottom due to biofilm accumulation or particle deposition. Combined with the drainage pipe, it ensures uniform water flow through the packing layer, avoiding localized water accumulation and short-circuiting. The thickness ratio of the upper packing layer 31, main matrix layer 32, and lower packing layer 33 is preferably 1:2-4:1-1.5.

[0066] like Figure 8 As shown, the long-staple cotton holding pipe 34 is used to fill pretreated long-staple cotton. It has an open top and liquid outlets on the sidewalls and bottom. The outlets have a diameter of 8-12 mm and a porosity of 30-50%. The long-staple cotton holding pipe 34 is primarily placed within 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 holding pipe 34 and the horizontal plane is 15-75° to increase the contact area between the nitrogen-containing wastewater and the long-staple cotton holding pipe 34. The upper opening of the long-staple cotton holding pipe 34 facilitates the replenishment of long-staple cotton. The provision of the liquid outlets with a diameter of 8-12 mm not only allows the enzyme molecules to diffuse efficiently to the cotton surface, but also prevents the accumulation of large molecular byproducts (such as lignin fragments) within the pipe, effectively solving the problem of insufficient reaction. The porosity of the liquid outlet is set to 30%-50%, which can take into account both mass transfer efficiency and structural stability. A high porosity (such as >50%) will significantly reduce the mechanical strength of the pipeline, and the cotton may absorb water and expand, causing the pipe to deform or rupture; a low porosity (<30%) will limit the circulation of the enzyme solution, thereby forming a reaction dead zone and reducing the enzymatic hydrolysis efficiency.

[0067] The long-staple cotton in the present application is preferably derived from waste textiles, which can be derived from old clothes in the home, household waste textiles, scraps and waste materials from the production process of textile factories and garment factories, etc. The system of the present application can reuse the waste, turn waste into treasure, and achieve the effect of treating waste with waste. Before use, the long-staple cotton can be subjected to simple pretreatments such as collection, washing, drying, and cutting. In terms of mass fraction, the long-staple cotton 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. It is enzymatically hydrolyzed using cellulase solution. After the prepared enzymatic hydrolyzate is added to the artificial wetland, it is gradually decomposed under the action of microorganisms, releasing low-molecular-weight organic matter that can be used by denitrifying bacteria, continuously and stably removing nitrogen from nitrogen-containing wastewater with a low carbon-nitrogen ratio, and 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 holding pipe 34 via the first pipe 13 and the third pipe 14; at the same time, the nitrogen-containing wastewater in the nitrogen-containing wastewater storage container 21 is transported to the wetland filler system 30 via the second pipe 23 and the fourth pipe 24. The cellulase solution in the long-staple cotton holding pipe 34 comes into contact with the long-staple cotton and undergoes enzymatic hydrolysis, resulting in a long-staple cotton enzymatic hydrolyzate whose main components are cellulose hydrolysis products (such as glucose, cellobiose, cellooligosaccharides and other soluble organic matter). Because the outer wall of the long-staple cotton holding pipe 34 is provided with a liquid outlet, the long-staple cotton enzymatic hydrolyzate can flow from the liquid outlet into the artificial wetland as an organic carbon source for denitrification. In the artificial wetland, microorganisms use the organic carbon source as an electron donor to begin heterotrophic denitrification and denitrification, gradually reducing nitrate (NO3-) to nitrogen gas (N2). The long-staple cotton enzymatic hydrolyzate produced in the long-staple cotton containing pipe 34 can continuously provide an organic carbon source for the artificial wetland, maintain the long-term operation of the denitrification process, and be beneficial to improving the denitrification efficiency of the artificial wetland system.

[0068] The present application also discloses an artificial wetland enhanced denitrification system based on dynamic regulation of carbon sources by enzymatic hydrolysis of long-staple cotton for the treatment of nitrogen-containing wastewater. The application of this system can continuously release carbon sources in artificial wetlands, maintain the long-term operation of the denitrification process, and effectively improve the nitrogen removal efficiency of the wetland system, thereby reducing the risk of eutrophication.

[0069] The present application also discloses a method for enhanced denitrification in artificial wetlands with a dynamic regulation of carbon sources based on enzymatic hydrolysis of long-staple cotton. The denitrification method uses the aforementioned system for enhanced denitrification in artificial wetlands with a dynamic regulation of carbon sources based on 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 in a cellulase solution storage container 11 and adjust the pH to 6.5-7.5. In this step, the pH can be adjusted using conventional acid or alkali, preferably hydrochloric acid solution or sodium hydroxide solution.

[0071] Step 2: Place the nitrogen-containing wastewater in the 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 pretreated long-staple cotton into the long-staple cotton receiving pipe 34. In this step, the amount of long-staple cotton is excessive relative to the enzyme solution, that is, as long as the long-staple cotton is excessive, the amount of excess can be selected according to actual conditions.

[0073] Step 4: Start the first peristaltic pump 12 and the second peristaltic pump 22. The volume of the cellulase solution and the nitrogen-containing wastewater entering the wetland filler system 30 satisfies the following formula:

[0074]

[0075] Among them, C / N is the carbon-nitrogen ratio, that is, the total COD value to the total N concentration, C a is the COD value corresponding to the addition of cellulase solution (the concentration of the cellulase solution is selected, and this value can be obtained from the above table). The nitrogen concentration of the cellulase solution is negligible. V b1 is the volume of nitrogen-containing wastewater inflow (can be measured), C b1 is the COD value of nitrogen-containing wastewater (can be measured), C b2 is the nitrogen (total nitrogen) concentration of nitrogen-containing wastewater (can be measured), V a is the volume of the added cellulase solution. It can be seen that when the C / N ratio to be adjusted is preset (such as 4, 5, etc.) and the concentration of the cellulase solution is selected, the required volume of the cellulase solution can be calculated, and the volume ratio n of the nitrogen-containing wastewater influent volume to the cellulase solution volume can be further obtained.

[0076] The flow rate of the first peristaltic pump 12 is: Where V is the effective volume of the artificial wetland, a is the hydraulic retention time of the cellulase solution, and n is the volume ratio of the nitrogen-containing wastewater inlet volume to the cellulase solution volume. 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 the nitrogen-containing wastewater, and n is 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 is the same, preferably ≥ 18 hours.

[0077] Example 1 Construction of an artificial wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton

[0078] 1. Constructing a wetland filler system

[0079] In this embodiment, the artificial wetland adopts downward flow, and the wetland filling system 30 is filled with an upper filling layer 31, a main matrix layer 32 and a lower filling layer 33 from top to bottom, wherein the upper filling 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, and the lower filling layer 33 includes quartz sand with a thickness of 10 cm and a particle size of 6 mm. The upper filling layer 31 is planted with wetland plants 35 canna.

[0080] During the filling process of the main matrix layer 32, a long-staple cotton receiving channel 34 is inserted. This channel 34 is open at the top, with outlet holes with a diameter of 8 mm and a porosity of 30% defined in the sidewalls and bottom. The axis of the long-staple cotton receiving channel 34 forms a 15° angle with the horizontal plane. The long-staple cotton in this embodiment is sourced from used clothing. After simple pre-processing, such as collection, washing, drying, and cutting, the recycled clothing is then filled into the long-staple cotton receiving channel 34.

[0081] The lower packing layer 33 is provided with a porous water outlet pipe 36, the pore diameter of the porous water outlet pipe 36 is 1 mm, and the pore density is 8 holes / 10 cm 2 , the tube wall is covered with 100 mesh nylon mesh.

[0082] 2. Construction of a cellulase solution storage and delivery device 10 and a nitrogen-containing wastewater storage and delivery device 20

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

[0084] 3. Operate the denitrification system

[0085] During operation, the inoculated sludge was taken from the secondary sedimentation tank of the Songjiang Wastewater Treatment Plant in Shanghai. After being sealed and placed for 2 days, it became anaerobic activated sludge. A small amount of diluted sludge suspension was added to the configured nitric nitrogen wastewater, and a certain amount of nutrients were added (their components are shown in the table below). The volume ratio of nutrients to influent was 1:1000. After stirring evenly, it was added to the artificial wetland device to acclimate the microorganisms. The total acclimatization time was 30 days, during which the water was changed every three days to ensure sufficient carbon source to ensure normal growth of microorganisms. After 30 days, yellow-brown sludge flocs were observed on the surface of quartz sand and elemental sulfur particles in the artificial wetland, occasionally accompanied by small bubbles. At this time, the artificial wetland film can be considered to have been successfully formed. Then it entered the trial operation stage, and after the effluent indicators stabilized, it entered the formal experimental stage.

[0086]

[0087] Example 2 Construction of a constructed wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton

[0088] 1. Constructing a wetland filler system

[0089] In this embodiment, the artificial wetland adopts downward flow, and the wetland filling system 30 is filled with an upper filling layer 31, a main matrix layer 32 and a lower filling layer 33 from top to bottom, wherein the upper filling 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 filling layer 33 includes quartz sand with a thickness of 15 cm and a particle size of 8 mm, and the upper filling layer 31 is planted with wetland plants 35 calamus.

[0090] During the filling process of the main matrix layer 32, a long-staple cotton receiving channel 34 is inserted. This channel 34 is open at the top, with outlet holes with a diameter of 12 mm and a porosity of 50% defined on the sidewalls and bottom. The axis of the long-staple cotton receiving channel 34 forms a 75° angle with the horizontal plane. In this embodiment, the long-staple cotton is sourced from used clothing. After simple pre-processing, such as collection, washing, drying, and cutting, the recycled clothing is then filled into the long-staple cotton receiving channel 34.

[0091] The lower packing layer 33 is provided with a porous water outlet pipe 36, the pore diameter of the porous water outlet pipe 36 is 2 mm, and the pore density is 12 holes / 10 cm 2 , the tube wall is covered with 200 mesh nylon mesh.

[0092] 2. Construction of a cellulase solution storage and delivery device 10 and a nitrogen-containing wastewater storage and delivery device 20

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

[0094] 3. Operate the denitrification system

[0095] During operation, inoculated sludge is taken from the secondary sedimentation tank of Songjiang Sewage Treatment Plant in Shanghai, and becomes anaerobic activated sludge after being sealed and placed for 5d. A small amount of sludge dilution suspension is added to the configured nitric nitrogen wastewater, and quantitative nutrients (same as Example 1) are added. The nutrient element and water volume ratio is 1: 1000, and after stirring, it is added into the artificial wetland device to acclimate microorganisms. The total acclimation time is 30 days, during which water is changed every three days to ensure that the carbon source is sufficient to ensure that the microorganism can grow normally. After 30 days, it can be observed that yellow-brown sludge flocs are generated on the surface of quartz sand and elemental sulfur particles in the artificial wetland, occasionally accompanied by small bubbles. Now it can be considered that the artificial wetland film is successful. Then enter the trial operation stage, and enter the formal experimental stage after the effluent index is stable.

[0096] Example 3 Construction of a constructed wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton

[0097] 1. Constructing a wetland filler system

[0098] In this embodiment, the artificial wetland adopts downward flow, and the wetland filling system 30 is filled with an upper filling layer 31, a main matrix layer 32 and a lower filling layer 33 from top to bottom, wherein the upper filling 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 filling layer 33 includes quartz sand with a thickness of 10 cm and a particle size of 7 mm, and the upper filling layer 31 is planted with wetland plants 35 water plantain.

[0099] During the filling process of the main matrix layer 32, a long-staple cotton receiving channel 34 is inserted. This channel 34 is open at the top, with outlet holes with a diameter of 10 mm and a porosity of 40% defined on the sidewalls and bottom. The axis of the long-staple cotton receiving channel 34 forms a 45° angle with the horizontal plane. In this embodiment, the long-staple cotton is sourced from recycled clothing. After simple pre-processing, such as collection, washing, drying, and cutting, the recycled clothing is then filled into the long-staple cotton receiving channel 34.

[0100] The lower packing layer 33 is provided with a porous water outlet pipe 36, the pore diameter of the porous water outlet pipe 36 is 1.5 mm, and the pore density is 10 holes / 10 cm 2 , the tube wall is covered with 160 mesh nylon mesh.

[0101] 2. Construction of a cellulase solution storage and delivery device 10 and a nitrogen-containing wastewater storage and delivery device 20

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

[0103] 3. Operate the denitrification system

[0104] During operation, inoculated sludge is taken from the secondary sedimentation tank of Songjiang Sewage Treatment Plant in Shanghai, and is sealed and placed for 3d to become anaerobic activated sludge. A small amount of sludge dilution suspension is added to the configured nitric nitrogen wastewater, and quantitative nutrients (same as Example 1) are added. The nutrient element and water volume ratio is 1: 1000, and after stirring, it is added to the artificial wetland device to acclimate microorganisms. The total acclimation time is 30 days, during which water is changed every three days to ensure that the carbon source is sufficient to ensure that microorganisms can grow normally. After 30 days, it can be observed that yellow-brown sludge flocs are generated on the surface of quartz sand and elemental sulfur particles in the artificial wetland, occasionally accompanied by small bubbles. Now it can be considered that the artificial wetland film is successful. Then enter the trial operation stage, and enter the formal experimental stage after the effluent index is stable.

[0105] Example 4 Construction of a constructed wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton

[0106] 1. Constructing a wetland filler system

[0107] In this embodiment, the artificial wetland adopts downward flow, and the wetland filling system 30 is filled with an upper filling layer 31, a main matrix layer 32 and a lower filling layer 33 from top to bottom, wherein the upper filling 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 filling layer 33 includes quartz sand with a thickness of 10 cm and a particle size of 6 mm, and wetland plants 35 water lilies are planted in the upper filling layer 31.

[0108] During the filling process of the main matrix layer 32, a long-staple cotton receiving channel 34 is inserted. This channel 34 is open at the top, with outlet holes with a diameter of 10 mm and a porosity of 50% defined on the sidewalls and bottom. The axis of the long-staple cotton receiving channel 34 forms a 30° angle with the horizontal plane. The long-staple cotton in this embodiment is sourced from used clothing. After simple pre-processing, such as collection, washing, drying, and cutting, the recycled clothing is then filled into the long-staple cotton receiving channel 34.

[0109] The lower packing layer 33 is provided with a porous water outlet pipe 36, the pore diameter of the porous water outlet pipe 36 is 2 mm, and the pore density is 12 holes / 10 cm 2 , the tube wall is covered with 200 mesh nylon mesh.

[0110] 2. Construction of a cellulase solution storage and delivery device 10 and a nitrogen-containing wastewater storage and delivery device 20

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

[0112] 3. Operate the denitrification system

[0113] During operation, inoculated sludge is taken from the secondary sedimentation tank of Songjiang Sewage Treatment Plant in Shanghai, and becomes anaerobic activated sludge after being sealed and placed for 5d. A small amount of sludge dilution suspension is added to the configured nitric nitrogen wastewater, and quantitative nutrients (same as Example 1) are added. The nutrient element and water volume ratio is 1: 1000, and after stirring, it is added into the artificial wetland device to acclimate microorganisms. The total acclimation time is 30 days, during which water is changed every three days to ensure that the carbon source is sufficient to ensure that the microorganism can grow normally. After 30 days, it can be observed that yellow-brown sludge flocs are generated on the surface of quartz sand and elemental sulfur particles in the artificial wetland, occasionally accompanied by small bubbles. Now it can be considered that the artificial wetland film is successful. Then enter the trial operation stage, and enter the formal experimental stage after the effluent index is stable.

[0114] Example 5 Treatment of nitrogen-containing wastewater

[0115] This example uses the artificial wetland enhanced denitrification system based on dynamic carbon source regulation of long-staple cotton enzymatic hydrolysis constructed in Example 1. The effective volume of the wetland filler system of this system is 2L. This example is divided into 4 stages. The first stage is from 1 to 20 days, C / N=1, the second stage is from 21 to 40 days, C / N=2, the third stage is from 41 to 60 days, C / N=3, and the fourth stage is from 61 to 80 days, C / N=4. Regarding the volume calculation of the cellulase solution, taking the second stage as an example, 1L (V b1 ), COD value is 30mg / L (C b1 ), total nitrogen concentration is 40mg / L(C b2 ) is put into the wastewater storage container 21, the cellulase solution is used at a concentration of 3 mg / L, and the pH is adjusted to 7. According to the above table, the corresponding COD value is 117.12 mg / L. Then, the volume of the cellulase solution V is calculated according to the following formula: a It is 0.43L.

[0116]

[0117] Therefore, 0.43 L of 3 mg / L cellulase solution was added to the cellulase solution storage container 11 and the pH was adjusted to 7. Excess pretreated long-staple cotton was filled into the long-staple cotton holding 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, and the flow rate of the first peristaltic pump 12 and the second peristaltic pump 22 was calculated by the following formula (where n = the volume ratio of the nitrogen-containing wastewater inlet to the 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). That is, every 24 hours, new nitrogen-containing wastewater with possibly different concentrations of ammonia nitrogen, nitrate nitrogen, and different COD values ​​will enter the wetland system. According to the above formula, before each water inflow, an appropriate C / N ratio can be selected, and a cellulase solution of any concentration within the scope of this application can be selected. Then, the volume of the corresponding cellulase solution and the flow rates of the first peristaltic pump 12 and the second peristaltic pump 22 can be calculated. It can be seen that the solution 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 by 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 results of nitrogen treatment of Example 5, Comparative Example 1 and Comparative Example 2 are as follows: Figure 9-11 As shown in the table below, the average concentration or average removal rate of 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, an additional carbon source was added to Example 5 and Comparative Example 1 until the theoretical C / N ratios reached 2.0, 3.0, and 4.0, respectively. Comparative Example 2 only added the same weight of long-staple cotton as in Example 5, without adding an additional carbon source.

[0128] The experimental results show that the total nitrogen removal rates of Comparative Example 1 and Example 5 significantly increased with increasing carbon source addition (C / N ratios of 2, 3, and 4), and were significantly better than those of Comparative Example 2. At a C / N ratio of 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, when no carbon source was added, was only 51.2%. This shows that the cellulase solution and long-staple cotton of the present application achieved similar results as 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. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A constructed wetland enhanced denitrification system based on dynamic carbon source regulation by enzymatic hydrolysis of long-staple cotton, characterized by: include: A cellulase solution storage and delivery device (10) comprises a cellulase solution storage container (11) and a first peristaltic pump (12) connected via a first pipe (13); A nitrogen-containing wastewater storage and delivery device (20) comprises a nitrogen-containing wastewater storage container (21) and a second peristaltic pump (22) connected via a second pipe (23); A wetland filler system (30) comprises an upper filler layer (31), a main matrix layer (32), a lower filler layer (33), and a long-staple cotton holding pipe (34) located in the main matrix layer (32); the upper end of the long-staple cotton holding pipe (34) is connected to a first peristaltic pump (12) via a third pipe (14); and the upper filler layer (31) is connected to a second peristaltic pump (22) via a fourth pipe (24).

2. The artificial wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton according to claim 1, characterized in that: The long-staple cotton containing pipe (34) is an upper open structure, and the side wall and bottom of the long-staple cotton containing pipe (34) are provided with liquid outlet holes, the aperture of the liquid outlet holes is 8-12 mm, and the porosity is 30-50%.

3. The artificial wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis and dynamic regulation of carbon sources according to claim 1, characterized in that: The long-staple cotton receiving pipe (34) is used for filling pre-treated long-staple cotton, which comes from waste textiles.

4. The artificial wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton according to claim 1, characterized in that: The angle between the axis of the long-staple cotton containing pipe (34) and the horizontal plane is 15-75 degrees.

5. The artificial wetland enhanced denitrification system based on dynamic regulation of carbon source by enzymatic hydrolysis of long-staple cotton according to claim 1, characterized in that: 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.

6. The artificial wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis and dynamic regulation of carbon sources according to claim 1, characterized in that: Wetland plants (35) are planted in the upper filler layer (31); and / or The lower packing layer (33) is provided with a porous water outlet pipe (36), the pore diameter of the porous water outlet pipe (36) is 1-2 mm, and the pore density is 8-12 holes / 10 cm 2 The wall of the porous water outlet pipe (36) is covered with a 100-200 mesh nylon mesh.

7. The artificial wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis and dynamic regulation of carbon sources according to 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.

8. The artificial wetland enhanced denitrification system based on long-staple cotton enzymatic hydrolysis and dynamic regulation of carbon sources according to claim 7, 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.

9. Use of the artificial wetland enhanced denitrification system with dynamic carbon source regulation based on long-staple cotton enzymatic hydrolysis as claimed in claim 1 in treating nitrogen-containing wastewater.

10. A method for enhanced denitrification in artificial wetlands by dynamically regulating carbon sources based on enzymatic hydrolysis of long-staple cotton, characterized in that: The denitrification method uses a constructed wetland enhanced denitrification system based on dynamic carbon source regulation of long-staple cotton enzymatic hydrolysis according to any one of claims 1 to 8, and the denitrification method comprises the following steps: S1. placing a cellulase solution having a concentration of 2.5-4 mg / L in a cellulase solution storage container (11) and adjusting the pH to 6.5-7.5; S2, placing the nitrogen-containing wastewater in a wastewater storage container (21); S3, filling the long-staple cotton containing pipe (34) with pre-treated long-staple cotton; S4, starting the first peristaltic pump (12) and the second peristaltic pump (22); The volumes of cellulase solution and nitrogen-containing wastewater entering the wetland filler system satisfy the following formula: Among them, C a is the COD value corresponding to the cellulase solution, V a is the volume of cellulase solution added, V b1 is the volume of nitrogen-containing wastewater inflow, C b1 is the COD value of nitrogen-containing wastewater, C b2 is the nitrogen concentration of the nitrogenous 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 artificial wetland, a is the hydraulic retention time of the nitrogen-containing wastewater or the hydraulic retention time of the cellulase solution, and n is the volume ratio of the nitrogen-containing wastewater to the cellulase solution.

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