A new type of filler for enhancing sewage denitrification and a preparation method and a biofilm forming method thereof

Abstract

This invention discloses a novel packing material for enhancing wastewater denitrification, its preparation method, and biofilm formation method, relating to the field of wastewater treatment. The preparation method of the novel packing material includes modifying spent membrane fibers by soaking them in a sodium hypochlorite solution, soaking them in a coating solution containing reduced iron powder and dopamine hydrochloride, and drying them to obtain the final modified membrane fibers. This application addresses the problem of recycling spent membrane materials in membrane-based water treatment projects. It prepares a novel packing material using spent membrane materials as raw materials. The novel packing material successfully reduces the water contact angle on the packing surface, enhances the biofilm enrichment capacity per unit membrane area, and significantly increases the unit denitrification rate of the biofilm on the packing surface, solving the problems of difficulty in enriching biofilm and long biofilm formation time in spent membrane packing materials.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and in particular to a novel packing material for enhancing wastewater denitrification, its preparation method, and its biofilm formation method. Background Technology

[0002] Membrane separation technology is widely used in my country's water resources, energy, environment, and chemical industries. Among them, membrane bioreactors (MBRs) have become the most competitive technology in the municipal wastewater treatment industry due to their high efficiency in sludge-water separation and small footprint. Existing MBR systems mostly use reinforced polyvinylidene fluoride (PVDF) hollow fiber composite membranes, which have extremely high stability. However, the average design life of membrane modules is about 3 years. With the large-scale operation of MBR systems, a large amount of waste membranes that are difficult to treat using conventional solid waste treatment methods will be generated annually. Therefore, recycling waste membrane materials is an important method for solving my country's membrane solid waste problem.

[0003] Waste hollow fiber membrane filaments possess a high specific surface area, providing sites for microbial biofilm formation. When used as a liquid carbon source diffuser, hollow fiber membranes can effectively regulate the microenvironment on the packing surface to enrich denitrifying microorganisms in sludge. However, to mitigate membrane fouling, alkaline chemical cleaning agents are often used to treat fouled membrane modules during MBR operation, thus damaging the hydrophilic structure of the membrane surface and reducing its water permeability. Simultaneously, after years of fouling, hollow fiber membranes easily accumulate hydrophobic irreversible pollutants on the pore surface, further reducing the membrane's water production performance. Therefore, untreated waste hollow fiber membrane filaments cannot efficiently diffuse liquid carbon sources in the reverse direction for extended periods, resulting in difficulty in efficiently enriching denitrifying microorganisms in sludge and a long start-up time for biofilm formation. Summary of the Invention

[0004] This invention provides a novel packing material for enhancing wastewater denitrification, along with its preparation method and biofilm formation method. To overcome the problems of difficulty in enriching biofilm and long biofilm formation time in waste hollow fiber membranes, the waste hollow fiber membranes are modified to improve their ability to enrich denitrifying microorganisms, making them a novel packing material that can be used for wastewater denitrification treatment.

[0005] To address the aforementioned technical problems, one objective of this invention is to provide a method for preparing a novel packing material for enhancing wastewater denitrification, comprising the following steps:

[0006] (1) Obtain waste membrane fibers from waste hollow fiber membrane modules;

[0007] (2) The waste membrane fibers were soaked in a sodium hypochlorite solution with a pH of 8-9. After treatment, the residual chlorine exposure equivalent was 2000-100000 ppm·h. After washing and drying, the preliminarily modified membrane fibers were obtained.

[0008] (3) The waste membrane fibers are soaked in a coating solution, which includes 0.3wt%-0.7wt% reduced iron powder, 0.5wt%-1.5wt% dopamine hydrochloride and the balance solvent. After drying, the final modified membrane fibers are obtained.

[0009] By adopting the above scheme, soaking the waste membrane fibers in a sodium hypochlorite solution with a high residual chlorine equivalent can destroy the residual hydrophobic irreversible pollution in the waste membrane fibers and introduce hydrophilic groups to improve hydrophilicity. Compared with the traditional modification method of improving hydrophobicity of biological packing to facilitate the attachment of more microorganisms, this application uses sodium hypochlorite to improve the hydrophilicity of the packing, which can limit the types of attached microorganisms. When the biofilm is attached, the ecological niche of the community attached to the surface of the new packing is narrowed, which is conducive to the specific attachment of bacteria with similar functions, namely denitrifying microorganisms. The roughness of the membrane surface is another important factor affecting the rapid biofilm attachment of the membrane packing. Without affecting the hydrophilicity of the pores and the carbon source diffusion capacity, the roughness of the surface of the waste membrane fibers is controlled by in-situ polymerization modification of reduced iron powder, which further enriches the denitrifying biofilm.

[0010] Meanwhile, the pH of the sodium hypochlorite solution is controlled at 8-9. This is because under weakly acidic and neutral conditions, the high content of hypochlorous acid molecules in the sodium hypochlorite solution will damage the functional groups on the membrane surface and expose the hydrophobic framework, which is not conducive to the diffusion of the external carbon source in the membrane packing pores during membrane attachment.

[0011] As a preferred option, in step (2), the soaking time is 2h-10h.

[0012] By adopting the above scheme, the residual chlorine exposure equivalent during the modification process of waste membrane fibers is an important factor affecting the enrichment of denitrification biofilm in membrane packing. Controlling the soaking time of sodium hypochlorite solution can control the residual chlorine exposure equivalent of waste membrane fibers. A small residual chlorine exposure equivalent during modification will not be able to effectively destroy the residual hydrophobic irreversible membrane fouling in the pores of the waste membrane fibers, while a large residual chlorine exposure equivalent will oxidize and destroy the hydrophilic groups on the membrane surface, exposing the hydrophobic PVDF framework and increasing the hydrophobicity of the membrane packing.

[0013] As a preferred option, in step (3), the soaking time is 3h-5h.

[0014] As a preferred option, the waste hollow fiber membrane module is derived from MBRs in drinking water treatment, municipal sewage treatment, or industrial wastewater treatment plants.

[0015] As a preferred embodiment, the membrane material of the waste hollow fiber membrane module is at least one of cellulose acetate, polyvinylidene fluoride, polyacrylonitrile, and polypropylene.

[0016] As a preferred embodiment, the pore size of the waste hollow fiber membrane module is 0.02-0.2μm.

[0017] To address the aforementioned technical problems, a second objective of this invention is to provide a method for preparing a novel packing material for enhancing wastewater denitrification, thereby obtaining the novel packing material for enhancing wastewater denitrification.

[0018] To address the aforementioned technical problems, a third objective of this invention is to provide a novel packing material for enhancing wastewater denitrification in wastewater denitrification treatment equipment, specifically applicable to liquid carbon source diffusers.

[0019] To address the aforementioned technical problems, the fourth objective of this invention is to provide a biofilm attachment method for a novel packing material used to enhance wastewater denitrification, comprising the following steps:

[0020] During the biofilm formation start-up phase, sludge from the anoxic tank of an urban wastewater treatment plant with the A2 / O process as the main component is used as inoculated sludge. Nitrate solution prepared from the effluent of the secondary sedimentation tank of the wastewater treatment plant is used as the influent substrate. Denitrification carbon source is added as an external carbon source and injected into the biofilm formation tank through a new type of packing material. The carbon source diffuses from the inside of the membrane cavity of the new packing material outward.

[0021] During the biofilm formation period, the sludge concentration was maintained at 4000-6000 mg / L, the sludge retention time (SRT) of the system was set at 12h-36h, the hydraulic retention time (HRT) was set at 12h-36h, the dissolved oxygen (DO) concentration was controlled at <0.5 mg / L, the flux of the denitrification carbon source was 1L / (m2˙h), and its dosage was adjusted according to the carbon source demand.

[0022] As a preferred option, the concentration of the nitrate solution is 25-100 mg N / L.

[0023] As a preferred option, the external carbon source is a solution containing glucose and glacial acetic acid with a concentration of 5-20 g COD / L and a mass ratio of glucose to glacial acetic acid of (1-5):1.

[0024] By adopting the above scheme, it is not the case that the higher the concentration of the external carbon source, the better. When the carbon source concentration is too high, membrane fouling will occur inside the membrane attachment tank. Controlling the flux of the external carbon source can also prevent the pressure of the external carbon source addition pump from increasing, which could lead to the bursting of waste membrane fibers.

[0025] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0026] 1. This application addresses the issue of recycling waste membrane materials in membrane water treatment projects. It prepares a new type of packing material using waste membrane materials as raw materials. The new packing material successfully reduces the water contact angle on the packing surface, enhances the biofilm enrichment capacity per unit membrane area, and increases the unit denitrification rate of biofilm on the packing surface by 223%. This solves the problems of difficult biofilm enrichment and long biofilm formation time in waste membrane packing materials.

[0027] 2. This application first uses hypochlorous acid alkaline solution with high residual chlorine equivalent to destroy irreversible membrane pollutants in waste hollow fiber membranes, change the hydrophilicity and hydrophobicity of the membrane packing surface and enhance the carbon source diffusion capacity of the membrane packing pores, and then uses the self-polymerization reaction of dopamine hydrochloride combined with the in-situ polymerization of reduced iron powder to control the roughness of the membrane packing surface, thereby further enhancing the membrane surface's ability to enrich denitrification microorganisms.

[0028] 3. This application is suitable for hollow fiber composite membrane materials for wastewater treatment, which can realize the recycling of waste membrane modules and achieve efficient removal of nitrogen from wastewater. The denitrification biofilm enriched on the surface of the novel membrane packing has a denitrification rate that is much higher than that of ordinary activated sludge flocs. Attached Figure Description

[0029] Figure 1 This invention relates to a biofilm attachment system in a biofilm attachment method for enhancing novel packing materials for wastewater denitrification.

[0030] Figure 2 : This is the AFM characterization result of a novel packing material for enhancing wastewater denitrification in Example 1 of this invention;

[0031] Figure 3 : This is the AFM characterization result of a novel packing material for enhancing wastewater denitrification in Comparative Example 1 of this invention;

[0032] Figure 4 : This is the AFM characterization result of a novel packing material for enhancing wastewater denitrification in Comparative Example 5 of this invention;

[0033] The instruction manual includes Figure 1 The attached diagrams are labeled as follows: 1. Carbon source tank; 2. Inlet tank; 3. Biofilm formation tank; 4. New type of packing material; 5. Water pump; 6. Inlet pump; 7. Agitator; 8. Drain valve. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing a novel packing material for enhanced wastewater denitrification includes the following steps:

[0037] S1. Take the waste hollow fiber membrane module of the MBR of a municipal sewage treatment plant in Zhuhai City, Guangdong Province. The membrane material is PVDF and the membrane pore size is 0.1μm. Cut a number of membrane filaments with a length of 10cm from the membrane module. Select the membrane filaments with intact physical structure and scrape off the residual sludge on their surface to obtain the waste membrane filaments.

[0038] S2. The waste membrane fibers were soaked in a 10 g / L sodium hypochlorite solution (pH = 8) for 5 hours and then removed. At this time, the residual chlorine exposure equivalent was about 50,000 ppm·h. The residual chlorine content of the sodium hypochlorite solution was determined by NN-diethyl-p-phenylenediamine (DPD) spectrophotometry. The actual residual chlorine exposure equivalent value was obtained by multiplying the residual chlorine content by the soaking time. The residual hypochlorite alkaline solution on the surface was washed away with water and air-dried to obtain the preliminarily modified membrane fibers.

[0039] S3. The preliminarily modified membrane fibers are immersed in a coating solution (containing 0.5 wt% dopamine hydrochloride, 1 wt% reduced iron powder, and the remainder water) and treated for 4 hours. After treatment, the fibers are removed and air-dried to obtain the modified membrane fibers.

[0040] S4. Bundle the modified membrane fibers into a cluster, glue one end to the straight water pipe fitting with epoxy resin potting compound, and pot the other end with epoxy resin potting compound to obtain the novel filler.

[0041] The above-mentioned biofilm formation method for a novel packing material used to enhance wastewater denitrification, such as... Figure 1 As shown, a biofilm attachment system is designed, including a biofilm attachment tank, a carbon source tank connected to the biofilm attachment tank, and an inlet tank connected to the biofilm attachment tank. A water pump is installed between the carbon source tank and the biofilm attachment tank, and an inlet pump is installed between the inlet tank and the biofilm attachment tank. The aforementioned new packing material is installed in the biofilm attachment tank. A stirrer and a drain valve are also installed in the biofilm attachment tank, and the drain valve is connected to the side of the biofilm attachment tank.

[0042] The biofilm formation method includes the following steps: Sludge from the anoxic tank of a municipal wastewater treatment plant, primarily using the A2 / O process, is used as inoculum. A nitrate solution prepared from the secondary sedimentation tank effluent is used as the influent substrate, with COD content approximately 50 mg / L, NO3--N content approximately 50 mg / L, TN content approximately 60 mg / L, and TP content 0.1-0.5 mg / L. The carbon source tank is supplied with the external carbon source required for the novel packing biofilm. The denitrification carbon source flux is 1 L / (m2˙h), while maintaining the total external carbon source concentration at 100 mg / L. The external carbon source is a solution containing glucose and glacial acetic acid, with a concentration of 10 g COD / L and a glucose to glacial acetic acid mass ratio of 3:1. During the initial operation of the reactor, the sludge concentration in the biofilm formation tank is maintained at 4000-6000 mg MLSS / L. The sludge age and hydraulic retention time of the system are both set to 24 h, and the dissolved oxygen concentration is maintained <0.5 mg / L. After 7 days of enrichment, biofilm formation is completed.

[0043] Example 2

[0044] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in S3, the coating solution contains 0.3 wt% dopamine hydrochloride, 0.5 wt% reduced iron powder, and the balance is water.

[0045] Example 3

[0046] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in S3, the coating solution contains 0.7 wt% dopamine hydrochloride, 1.5 wt% reduced iron powder, and the balance is water.

[0047] Example 4

[0048] A method for preparing a novel packing material for enhanced wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in step S3, the waste membrane fibers are soaked in a 10 g / L sodium hypochlorite solution (pH = 8) and taken out after 2 hours. At this time, the residual chlorine exposure equivalent is 20,000 ppm·h.

[0049] Example 5

[0050] A method for preparing a novel packing material for enhanced wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in step S3, the waste membrane fibers are soaked in a 10 g / L sodium hypochlorite solution (pH = 8) and taken out after 10 hours. At this time, the residual chlorine exposure equivalent is 100,000 ppm·h.

[0051] Example 6

[0052] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in step S2, the waste membrane fibers are soaked in a sodium hypochlorite solution (pH=9).

[0053] Comparative Example 1

[0054] A method for preparing a novel packing material for enhanced wastewater denitrification includes the following steps:

[0055] S1. Take the waste hollow fiber membrane module from a municipal sewage treatment plant in Zhuhai City, Guangdong Province. The membrane material is PVDF and the membrane pore size is 0.1μm. Cut a number of membrane filaments with a length of 10cm from the membrane module. Select the membrane filaments with intact physical structure and scrape off the residual sludge on their surface to obtain the waste membrane filaments.

[0056] S2. Bundle the waste membrane fibers into a cluster, glue one end to the straight water pipe fitting with epoxy resin potting compound, and pot the other end with epoxy resin potting compound to obtain the new type of filler.

[0057] Comparative Example 2

[0058] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in step S2, the waste membrane fibers are soaked in a sodium hypochlorite solution (pH=6).

[0059] Comparative Example 3

[0060] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in step S2, the waste membrane fibers are soaked in a sodium hypochlorite solution (pH=7).

[0061] Comparative Example 4

[0062] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in S3, the pre-modified membrane fibers are directly polished with reduced iron powder. That is, the pre-modified membrane fibers are completely embedded in the reduced iron powder, and the membrane fibers are moved so that their surface is rubbed evenly with the reduced iron powder for 15 minutes to fully induce physical etching and obtain the modified membrane fibers.

[0063] Comparative Example 5

[0064] A method for preparing a novel packing material for enhancing wastewater denitrification is provided. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that in S3, the preliminarily modified membrane fibers are immersed in a coating solution (containing 0.5 wt% dopamine hydrochloride and the remainder water), treated for 4 hours, removed, and air-dried to obtain the modified membrane fibers.

[0065] The biofilm formation method for a novel packing material used to enhance wastewater denitrification in Examples 2-5 and Comparative Examples 1-5 is the same as that in Example 1.

[0066] Comparative Example 6

[0067] A biofilm formation method for enhancing wastewater denitrification using a novel packing material is described. The steps, reagents, and process parameters used in each step are the same as in Example 1. The difference is that no novel packing material is installed in the biofilm formation tank.

[0068] Performance testing

[0069] 1. Unit denitrification rate of sludge: The denitrifying biofilm enriched by the novel packing material after biofilm attachment treatment in the examples or comparative examples was scraped off, washed three times with pure water, and then brought to a final volume to obtain a sludge mixture with a sludge concentration of 5000 mg MLSS / L (if the novel packing material was not used in the implementation plan, the sludge mixture from the biofilm attachment tank was taken directly). Nitrogen gas was introduced into the above sludge mixture to make the dissolved oxygen concentration <0.5 mg / L, and then sodium acetate and sodium nitrate were added until the COD concentration and NO3--N concentration were 200 mg / L and 20 mg N / L, respectively. The supernatant of the sludge mixture was taken at 20-minute intervals, and the concentrations of NH4+-N, NO2--N, and NO3--N were measured. After the experiment, the sludge concentration of the sludge mixture was measured, and the unit denitrification rate of the sludge was calculated. The test results are shown in Table 1 below.

[0070] 2. Water contact angle: The hydrophilicity and hydrophobicity of the surface of the novel packing prepared in the examples or comparative examples were measured using a water contact angle measuring instrument. The test results are shown in Table 1 below.

[0071] 3. Surface roughness: The root mean square roughness and average roughness of the surface of the novel filler prepared in the examples or comparative examples were measured using atomic force microscopy (AFM). The test results are shown in Table 1 below.

[0072] Table 1 - Performance test results of the novel packing material of this application

[0073]

[0074] Combination Figure 2-3 As shown in Table 1, the performance test results of Example 1 and Comparative Examples 1 and 6 indicate that after modification treatment and control of membrane surface roughness, the unit denitrification rate of the packing material after membrane attachment treatment is significantly improved, which is 3.23 times that of the original waste hollow fiber membrane filaments and 6.32 times that of simply inoculated sludge, respectively. This enhances the ability of the membrane surface to enrich denitrification microorganisms, indicating that the new packing material has a stronger ability to denitrify wastewater.

[0075] Based on the performance test results of Examples 1 and 6 and Comparative Examples 2-3 in Table 1, it can be seen that the denitrification rate and hydrophilicity of the denitrification biofilm enriched by the modified waste hollow fiber membrane packing treated with sodium hypochlorite modified solution at pH=8 and 9 are significantly higher than those of the modified waste hollow fiber membrane packing treated with alkaline hypochlorite modified solution at pH=6 and pH=7. This is because under weakly acidic and neutral conditions, the hypochlorite molecule content of the modified solution is too high, which will destroy the functional groups on the membrane surface and expose the hydrophobic PVDF framework, which is not conducive to the diffusion of the added carbon source in the pores of the membrane packing.

[0076] Combination Figure 2-4As shown in Table 1, the performance test results of Example 1 and Comparative Examples 1 and 4-5 indicate that the novel packing material modified by in-situ polymerization of reduced iron powder has a greater roughness than the unmodified / physically modified novel packing material. This is because the self-polymerization phenomenon of dopamine hydrochloride forms a coating layer on the surface of the membrane fibers, which increases the effective area of ​​the membrane fiber surface and facilitates the embedding of reduced iron powder, thus significantly improving the roughness of the packing material. This also makes it easier for denitrifying microorganisms to attach and grow on the surface of the packing material. This can be mutually verified with the fact that the unit denitrification rate of Example 1 is significantly improved compared with the unit denitrification rate of the unmodified / physically modified novel packing material.

[0077] Based on the performance test results of Examples 1 and 4-5 in Table 1, it can be seen that the denitrification biofilm enriched with modified waste hollow fiber membrane packing treated with a residual chlorine exposure equivalent of 50,000 ppm·h can achieve the optimal denitrification rate, with activities 1.73 times and 1.63 times that of modified waste hollow fiber membrane packing treated with residual chlorine exposure equivalents of 20,000 ppm·h and 100,000 ppm·h, respectively. The water contact angle of the modified waste hollow fiber membrane packing in Example 1 is stronger than that in Example 4 because the residual chlorine equivalent in Example 4 is smaller and cannot effectively destroy the residual hydrophobic irreversible membrane fouling in the pores of the waste membrane filaments. However, it is stronger than that in Example 5 because the residual chlorine equivalent is greater than 50,000 rpm·h, which will oxidize and destroy the hydrophilic groups on the membrane surface, exposing the hydrophobic PVDF skeleton of Example 5 and increasing the hydrophobicity of the membrane packing.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for preparing a novel packing material for enhanced wastewater denitrification, characterized in that, Includes the following steps: (1) Obtain waste membrane fibers from waste hollow fiber membrane modules; (2) The waste membrane fibers were soaked in a sodium hypochlorite solution with a pH of 8-9. After treatment, the residual chlorine exposure equivalent was 50,000 ppm·h. After washing and drying, the preliminarily modified membrane fibers were obtained. (3) The waste membrane fibers are soaked in a coating solution, which includes 0.3wt%-0.7wt% reduced iron powder, 0.5wt%-1.5wt% dopamine hydrochloride and the balance solvent. After drying, the final modified membrane fibers are obtained. In step (2), the soaking time is 5 hours and the concentration of sodium hypochlorite in the sodium hypochlorite solution is 10 g / L.

2. The method for preparing a novel packing material for enhanced wastewater denitrification as described in claim 1, characterized in that, In step (3), the soaking time is 3h-5h.

3. The method for preparing a novel packing material for enhanced wastewater denitrification as described in claim 1, characterized in that, The waste hollow fiber membrane modules are derived from MBRs in drinking water treatment, municipal sewage treatment, or industrial wastewater treatment plants.

4. The method for preparing a novel packing material for enhanced wastewater denitrification as described in claim 1, characterized in that, The membrane material of the waste hollow fiber membrane module is at least one of cellulose acetate, polyvinylidene fluoride, polyacrylonitrile, and polypropylene, and the membrane pore size of the waste hollow fiber membrane module is 0.02-0.2μm.

5. A novel packing material for enhanced wastewater denitrification prepared by the preparation method of any one of claims 1-4.

6. The application of a novel packing material for enhancing wastewater denitrification as described in claim 5 in a wastewater denitrification treatment device.

7. A biofilm formation method for a novel packing material used to enhance wastewater denitrification as described in claim 5, characterized in that, Includes the following steps: During the biofilm formation start-up phase, sludge from the anoxic tank of an urban wastewater treatment plant with the A2 / O process as the main component is used as inoculated sludge. Nitrate solution prepared from the effluent of the secondary sedimentation tank of the wastewater treatment plant is used as the influent substrate. Denitrification carbon source is added as an external carbon source and injected into the biofilm formation tank through a new type of packing material. The carbon source diffuses from the inside of the membrane cavity of the new packing material outward. During biofilm formation, the sludge concentration is maintained at 4000-6000 mg / L, the sludge retention time (SRT) of the system is set at 12h-36h, the hydraulic retention time (HRT) is set at 12h-36h, the dissolved oxygen (DO) concentration is controlled at <0.5 mg / L, the flux of the denitrification carbon source is 1 L / (m2˙h), and its dosage is adjusted according to the carbon source demand.

8. The biofilm formation method for a novel packing material used to enhance wastewater denitrification as described in claim 7, characterized in that, The concentration of nitrate solution is 25-100 mg N / L.

9. A biofilm attachment method for a novel packing material used to enhance wastewater denitrification as described in claim 7, characterized in that, The added carbon source is a solution containing glucose and glacial acetic acid, with a concentration of 5-20 g COD / L and a mass ratio of glucose to glacial acetic acid of (1-5):1.

Images