Preparation and application of a composite carrier for enhancing sulfur autotrophic denitrification

Abstract

The application discloses a kind of preparation and application of reinforced sulfur autotrophic denitrification composite carrier filler, belong to wastewater treatment technical field.The composite carrier and embedding are included;The composite carrier is formed by polyvinyl alcohol and biochar, and the embedding is formed by riboflavin and denitrifying pseudomonas.The riboflavin, denitrifying pseudomonas and composite carrier are embedded together in the application, which can improve the mass transfer effect, effectively disperse riboflavin and bacterial body, avoid bacterial body loss, and help maintain the treatment capacity of denitrifying pseudomonas.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification. BACKGROUND

[0002] Sulfur autotrophic denitrification uses Pseudomonas denitrificans as the denitrifying bacteria, and uses elemental sulfur as the electron donor and NO3 - As the electron acceptor under anoxic conditions, thereby realizing the process of denitrification. Compared with the traditional denitrification process using heterotrophic facultative anaerobic bacteria, the method has the advantages of little sludge production, no need for additional carbon source, and low operation cost when treating low C / N wastewater. However, the sulfur autotrophic denitrification technology still faces many new challenges, such as low efficiency and easy loss of bacteria. SUMMARY

[0003] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] The application of the microorganism embedding and immobilization technology in wastewater treatment has the advantages of high biomass, obvious dominant bacteria, little loss, small footprint of the treatment device, and low sludge production, and can make the system obtain better treatment effect under more harsh conditions. In order to improve the loading of microorganisms and the repeatability of the carrier, the inorganic carrier and the organic carrier are usually used together in a specific proportion (i.e., the composite carrier), the composite carrier shows the complementary advantages of the inorganic carrier and the organic carrier, and the selection of a suitable immobilized carrier depends on many factors, including reusability, non-toxicity, and cost-effectiveness. Therefore, the application uses the composite carrier to improve the performance of the immobilized microspheres in wastewater treatment by using biochar and polyvinyl alcohol.

[0005] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the problems in the prior art, the application provides a preparation and application of a composite carrier filler for enhancing sulfur autotrophic denitrification.

[0004] In view of the

[0006] To achieve the above object, the present application provides the following technical solutions.

[0007] The reinforced sulfur autotrophic denitrification composite carrier filler comprises a composite carrier and an embedding material, wherein the composite carrier is composed of polyvinyl alcohol and biochar, and the embedding material is composed of riboflavin and Pseudomonas denitrificans.

[0008] Further, the mass fraction of the polyvinyl alcohol in the composite carrier is 4-6% (w / v), and the mass fraction of the biochar in the composite carrier is 1-2.5% (w / v).

[0009] Further, the mass percentage of the riboflavin in the embedding material is 1.5-3.5%, and the volume ratio of the Pseudomonas denitrificans to the composite carrier is 10:1.

[0010] Further, the culture method of the Pseudomonas denitrificans comprises the following steps: inoculating the Pseudomonas denitrificans into an enriched liquid medium to obtain an enriched liquid bacterial solution, centrifuging, and obtaining wet bacterial bodies.

[0011] Further, the preparation method of the enriched liquid medium comprises the following steps: mixing 5 g of sodium thiosulfate, 1 g of glucose, 0.01 g of ferrous chloride dodecahydrate, 2 g of potassium dihydrogen phosphate and 0.5 g of magnesium chloride hexahydrate; adjusting the pH value of the system to 7.0, high-temperature sterilization, and obtaining the enriched liquid medium.

[0012] The present application also provides a preparation method of the reinforced sulfur autotrophic denitrification composite carrier filler.

[0013] (1) adding polyvinyl alcohol into water, heating to 95-99℃ to make it into a viscous liquid, cooling to 25-35℃, adding biochar, sterilizing, and cooling to room temperature to obtain a composite carrier;

[0014] (2) adding Pseudomonas and riboflavin into the obtained composite carrier in sequence, stirring to mix, dropping the obtained mixture into a crosslinking agent to react, obtaining immobilized microspheres, freezing, thawing and air-drying to obtain the reinforced sulfur autotrophic denitrification composite carrier filler.

[0015] Further, the diameter of the immobilized microspheres is 3-5 mm, and the crosslinking agent is a calcium chloride aqueous solution, wherein the mass concentration of the calcium chloride is 3%.

[0016] Further, the freezing is freezing preservation at-20℃ or below for 12-24 h, and the thawing and air-drying is thawing and air-drying at 0-3℃ for 1-2 h, and then thawing and air-drying at room temperature for 6 h.

[0017] The application also provides application of the reinforced sulfur autotrophic denitrification composite carrier filler in wastewater treatment, and the reactor body used in the denitrification process is an upflow reactor, the reactor body is sequentially provided with a water inlet area, a filler area and a water outlet area from bottom to top, the water inlet area is communicated with a water inlet system, the water outlet area is communicated with a water outlet system, and the filler area is filled with the reinforced sulfur autotrophic denitrification composite carrier filler and sulfur.

[0018] Compared with the prior art, the application has the following advantages:

[0019] The riboflavin is embedded in the composite carrier as a redox mediator, so that the rate of sulfur autotrophic denitrification is greatly improved, the hydraulic retention time is shortened, and the wastewater treatment cost is effectively reduced.

[0020] The polyvinyl alcohol hydrogel has the advantages of good elasticity, great flexibility and high water content rate. The polyethylene is used as one of main components of the carrier material for cell immobilization, and has the comprehensive effect of material adsorption-biodegradation. In addition, the biochar is used as another component of the carrier material because the biochar has the advantages of large specific surface area, high porosity and strong adsorption capacity, so that the effect of enriching the Pseudomonas denitrificans can be achieved to increase the concentration of the Pseudomonas denitrificans.

[0021] The biological filler and the denitrification process provided by the application have the advantages of fast reaction tank starting and short hydraulic retention time, and have a very good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0023] Figure 1 It is a working state schematic diagram of the upflow fixed bed reactor in the sulfur autotrophic denitrification method of the application, wherein, 1 is a water inlet tank, 2 is a peristaltic pump, 3 is a water inlet, 4 is a filler reaction area, 5 is a cobble support layer, 6 is a multi-filter hole support plate, 7 is a sludge discharge port, 8 is an overflow pipe, 9 is a water outlet tank, 10 is a reactor, 11 is an L-shaped support;

[0024] Figure 2 It is a curve of the change of the removal rate of nitrate nitrogen in the simulated wastewater after the biological filler in the embodiment 1 (corresponding to the experimental example 1 in the drawing) and the control example 1 is filled into the upflow fixed bed reactor and reacts for a period of time;

[0025] Figure 3 Figure 6 shows the nitrate nitrogen removal rate curve in actual wastewater after the biological filler in Example 2 of the present application (corresponding to Experimental Example 2 in the figure) and Comparative Example 2 was filled into an upflow fixed bed reactor and reacted for a certain period of time;

[0026] Figure 4 Figure 7 shows the nitrate nitrogen removal rate curve in actual wastewater after the biological filler in Comparative Example 3 of the present application (corresponding to Comparative Example 3 in the figure) was filled into an upflow fixed bed reactor and reacted for a certain period of time;

[0027] Figure 5 Figure 8 shows the nitrate nitrogen removal rate curve in actual wastewater after the biological filler in Comparative Example 4 of the present application (corresponding to Comparative Example 4 in the figure) was filled into an upflow fixed bed reactor and reacted for a certain period of time;

[0028] Figure 6 Figure 9 shows the nitrate nitrogen removal rate curve in actual wastewater after the biological filler in Comparative Example 5 of the present application (corresponding to Comparative Example 5 in the figure) was filled into an upflow fixed bed reactor and reacted for a certain period of time. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present application will now be described in detail, which should be considered to be illustrative of certain aspects, features and embodiments of the present application and are not intended to limit the scope of the present application.

[0030] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of a parameter, unless otherwise stated, each intervening value of the parameter is also specifically included within the scope of the present application. The above description is that of current embodiments of the application. Various alterations and changes can be made without departing from the spirit and scope of the application. It is intended that the application be construed as including all such alterations and changes.

[0031] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict, the present specification will control.

[0032] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the application. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0033] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed material or step.

[0034] The "room temperature" described in the present application is 25±2℃, unless otherwise specified.

[0035] The raw materials used in the following examples of the present application are commercially available.

[0036] The present application provides a kind of reinforced sulfur autotrophic denitrification composite carrier filler, it includes composite carrier and embedding;The embedding riboflavin and denitrifying pseudomonas;The composite carrier includes polyvinyl alcohol and biochar.

[0037] The present application provides a kind of reinforced sulfur autotrophic denitrification composite carrier filler preparation method, comprising the following steps:

[0038] S1, preparation of pseudomonas body, carrier;Polyvinyl alcohol is dissolved in water, heated into viscous liquid, then cooled to 25-35℃, add biochar, obtain composite carrier;Then the composite carrier is sterilized and cooled to room temperature;

[0039] S2, denitrifying pseudomonas and riboflavin are sequentially added in the obtained composite carrier, stirring 20min, obtain mixture;

[0040] S3, the obtained mixture is dropped into crosslinking agent solution to react, and immobilized microspheres are obtained.

[0041] S4, the immobilized microspheres are taken out and frozen, thawed and air dried, to obtain composite carrier biological filler.

[0042] In some preferred embodiments of the present application, the preparation method of the denitrifying pseudomonas body in step S1 is as follows: the denitrifying pseudomonas is inoculated into an enrichment liquid medium to culture, to obtain an enrichment liquid bacterial solution, the enrichment liquid bacterial solution is centrifuged to obtain wet bacterial bodies;The enrichment liquid medium contains 5g sodium thiosulfate, 1g glucose, 0.01g ferrous chloride dodecahydrate, 2g potassium dihydrogen phosphate and 0.5g magnesium chloride hexahydrate, and the pH value of the system is adjusted to 7.0 and high-temperature sterilized. Preferably, the inoculation and culture conditions of the denitrifying pseudomonas in the enrichment liquid medium are as follows: 30℃, culture time is 24h, centrifugal speed is 6000r / min, and centrifugal time is 10min.

[0043] In step S1 of some preferred embodiments of the present application, the preparation method of the composite carrier is as follows: polyvinyl alcohol is added into water, heated to 95-99℃ (preferably 95℃) to become a viscous liquid (the temperature helps the polyvinyl alcohol to dissolve in water), cooled to 25-35℃ (preferably cooled to 20-26℃, more preferably 25℃), biochar is added to obtain the composite carrier, and sterilization is performed; wherein the mass percentage of polyvinyl alcohol is 4-6%, preferably 5%, and the mass percentage of biochar is 1-2.5%, preferably 1.5%.

[0044] In step S2 of some preferred embodiments of the present application, the composite carrier is mixed with the wet Pseudomonas denitrificans bacteria at a volume ratio of 10:1, so that the wet Pseudomonas denitrificans bacteria are adsorbed and dispersed on the composite carrier; then riboflavin is added to obtain a mixture. The mass fraction of riboflavin is 1.5-3.5%, preferably 2.5%.

[0045] In step S3 of some preferred embodiments of the present application, the mixture is dropped into a crosslinking agent solution using a needle tube for reaction, to obtain immobilized microspheres with a diameter of 3-5mm; the crosslinking agent solution is a 3% calcium chloride aqueous solution.

[0046] In step S4 of some preferred embodiments of the present application, the immobilized microspheres prepared in step S3 are taken out, washed with deionized water, frozen at-20℃ or below for 12-24h, preferably 24h, thawed at low temperature (0-3℃) for 1-2h, and finally thawed at room temperature for 6h, to obtain the composite biological filler.

[0047] The present application provides an application of a composite carrier for strengthening sulfur autotrophic denitrification, which uses an upflow fixed bed reactor as a reaction tank, performs sulfur autotrophic denitrification on wastewater, and sequentially arranges a water inlet area, a filler area, and a water outlet area in the reactor body from bottom to top. The water inlet area is connected to a water inlet system, the water outlet area is connected to a water outlet system, the filler area is filled with the composite carrier for strengthening sulfur autotrophic denitrification and sulfur, and the particle size of the composite carrier for strengthening sulfur autotrophic denitrification is between 3-5mm.

[0048] It should be noted that the denitrification method of the present application is not limited to the upflow fixed bed reactor, but can be any kind of filler reactor that directly contacts and reacts with wastewater containing nitrate nitrogen.

[0049] In the following embodiments of the present application, the device used for the application of the composite carrier is as follows: Figure 1As shown, the device comprises a water inlet pool 1, a denitrification reactor 10 and a water outlet pool 9; wherein the water inlet pool 1 is connected with one side of the lower end of the denitrification reactor 10, and a sewage pump 2 is arranged on the connecting pipeline of the two; the upper end of the denitrification reactor 10 is further connected with the water outlet pool 9; and the lowermost end of the denitrification reactor 10 is further provided with a sludge discharge port 7; wherein the denitrification reactor 10 is a continuous flow biofilm reactor, and an L-shaped support 11 is arranged on the inner wall surface of the denitrification reactor 10, which is fixed on the inner wall of the reactor 10 to support a multi-filter hole supporting plate 6; the multi-filter hole supporting plate 6 is provided with a plurality of water permeable holes, which play a role in distributing the inlet water; a pebble supporting layer 5 is filled above the multi-filter hole supporting plate 6, and a filler reaction zone 4 is above the pebble supporting layer 5; the filler reaction zone 4 is filled with a composite carrier filler for strengthening sulfur autotrophic denitrification. When the reactor starts to feed water, the sewage pump 2 is opened to pump the sewage in the water inlet pool 1 into the denitrification reactor 10 through the water inlet 3; the outlet water enters the water outlet pool 9 through the overflow pipe 8; at the same time, in order to maintain the activity of the denitrifying bacteria in the denitrification reactor 10, regular sludge discharge is carried out through the sludge discharge port 7.

[0050] In the following examples of the present application, the biochar is purchased from the market (Henan Jiahe Water Purification Material Co., Ltd.), and the specific composition of the biochar is not discussed as the content of the present application, which is not the innovation point of the present application. The conventional biochar in the art can realize the present application, and no more description is made.

[0051] The following examples are further illustrations of the technical solutions of the present application.

[0052] Example 1

[0053] 1) Pseudomonas denitrificans body: inoculate Pseudomonas denitrificans into an enrichment liquid medium to culture (the culture conditions are: culture temperature 30℃, culture time 24h) to obtain an enrichment liquid bacterial solution, and centrifuge (the centrifugation conditions of the enrichment liquid bacterial solution are: centrifugal speed 6000r / min, centrifugation time 10min) to obtain a wet bacterial body.

[0054] Preparation method of the enrichment liquid medium: mix 5g of sodium thiosulfate, 1g of glucose, 0.01g of ferrous chloride dodecahydrate, 2g of potassium dihydrogen phosphate and 0.5g of magnesium chloride hexahydrate; adjust the pH value of the system to 7.0 and high-temperature sterilize. The initial inoculation concentration of the Pseudomonas denitrificans in the enrichment liquid medium is OD 600 =0.8.

[0055] 2) Pretreatment of biochar: irradiate under an ultraviolet lamp for 25min to fully sterilize.

[0056] 3) Preparation of composite carrier: polyvinyl alcohol was added into water, heated to 95°C to become a viscous liquid, cooled to 30°C, and the pretreated biochar of step 2) was added to obtain a sample which was sterilized to obtain the composite carrier; wherein the mass percentage of polyvinyl alcohol was 5%, and the mass percentage of biochar was 1.8%.

[0057] 4) Strengthening of sulfur autotrophic denitrification composite carrier filler: the composite carrier obtained in step 3) was mixed with the Pseudomonas denitrificans in step 1) at a volume ratio of 10:1, so that the Pseudomonas wet bacteria body was adsorbed and dispersed on the composite carrier, then riboflavin with a mass fraction of 2.5% was added, and the three were mixed evenly; the obtained mixture was dropped into a crosslinking agent solution (the crosslinking agent solution was a calcium chloride aqueous solution, and the mass concentration of calcium chloride was 3%) using a needle type tube dropper to react, to obtain immobilized microspheres with a diameter of 3-5 mm;

[0058] The prepared immobilized microspheres were taken out, washed with deionized water, frozen and stored at -20°C or below for 24h, thawed at 0°C, air-dried for 2h, and finally thawed at room temperature to obtain the composite carrier biological filler.

[0059] The pilot-scale sulfur-iron composite autotrophic denitrification reactor was constructed and started up, and the prepared composite carrier biological filler and sulfur particles were loaded into the filler reaction zone 4 of the upflow reactor at a volume ratio of 2:1 as shown in Figure 1 The reactor was filled with artificial synthetic wastewater (the composition of the artificial synthetic wastewater was (g / L): 0.2166 KNO3, 0.2599 NaHCO3, 0.2166 KH2PO4), and low-flow continuous water was started, with a hydraulic retention time controlled at 4h, and the change of nitrate nitrogen in the influent and effluent was determined (see Figure 2 ).

[0060] Example 2 Synchronous denitrification effect on the secondary biochemical effluent of a certain mixed wastewater treatment plant (municipal domestic wastewater and industrial wastewater).

[0061] On the basis of Example 1, the treatment object was changed from artificial synthetic wastewater to the secondary biochemical effluent of a certain mixed wastewater treatment plant, and the water quality characteristics were as follows: COD 26.9-38.21 mg / L; TN 19.55-24.74 mg / L; NO3 - -N 18.63-22.65 mg / L; NO2 - -N 0.36-0.59 mg / L; NH4 + -N 0.56-1.5 mg / L; pH 7-8. The reactor after completion of the start-up was pumped into the above wastewater, with a hydraulic retention time of 4h, and during the operation, sampling analysis was performed, and the results are shown in the accompanying Figure 3 .

[0062] Comparative Example 1

[0063] The difference between the example 1 and the example 2 is that no riboflavin is added, i.e. the operation of step 4) is as follows: the composite carrier obtained in step 3) is mixed with the Pseudomonas body in step 1) at a volume ratio of 10:1, so that the Pseudomonas wet body is adsorbed and dispersed on the composite carrier, and then mixed uniformly; the obtained mixture is dropped into a crosslinking agent solution (the crosslinking agent solution is a calcium chloride aqueous solution, and the mass concentration of the calcium chloride is 3%) using a needle type dropper to react, so as to obtain immobilized microspheres with a diameter of 3-5 mm;

[0064] The prepared immobilized microspheres are taken out, washed with deionized water, and stored at-20℃ or below for 24 h, then thawed at 0℃, and dried twice, and finally thawed at room temperature, so as to obtain the composite carrier biological filler embedding riboflavin and Pseudomonas.

[0065] The filler prepared in the example 1 is used to remove nitrogen in the artificial synthetic wastewater, and the effect of nitrate nitrogen removal rate is as shown in Table 1. Figure 2

[0066] Comparative example 2

[0067] The difference between the example 1 and the example 2 is that no riboflavin is added, i.e. the operation of step 4) is as follows: the composite carrier obtained in step 3) is mixed with the Pseudomonas body in step 1) at a volume ratio of 10:1, so that the Pseudomonas wet body is adsorbed and dispersed on the composite carrier, and then mixed uniformly; the obtained mixture is dropped into a crosslinking agent solution (the crosslinking agent solution is a calcium chloride aqueous solution, and the mass concentration of the calcium chloride is 3%) using a needle type dropper to react, so as to obtain immobilized microspheres with a diameter of 3-5 mm; Figure 3

[0068] As shown in Table 1, it can be seen that the composite carrier biological filler in the examples 1-2 has an average concentration of nitrate nitrogen of about 3.74 mg / L and about 1.51 mg / L, respectively, and a nitrate nitrogen removal rate of about 90.75% and about 90.55%, respectively, under the corresponding experimental conditions of the upflow fixed bed reactor and the hydraulic retention time of 4 h. Figures 2-3

[0069] Compared with the comparative example 1, the average nitrate nitrogen removal rate of the example 1 is increased by 13.56% than that of the comparative example 1. During the operation, the nitrate nitrogen removal rate of the example 1 is always higher than that of the comparative example 1.

[0070] Compared with the comparative example 2, the average nitrate nitrogen removal rate of the example 2 is increased by 12.8% than that of the comparative example 2.

[0071] Therefore, it is proved that the immobilized particles embedding denitrifying Pseudomonas with good hydrophilicity and biological affinity are prepared by using the biological charcoal with good biological affinity and the high molecular material polyvinyl alcohol as the carrier of immobilized microorganisms, and adding the riboflavin as the oxidation-reduction mediator, which accelerates the mass transfer process of the reaction system, and has great practical value and popularization prospect.

[0072] Comparative example 3 ​​​

[0073] The same as example 2, except that the mass concentration of riboflavin is 1%, and the filler prepared in this control example is used to remove nitrogen in the secondary biochemical effluent of a certain mixed sewage treatment plant in example 2. The results are shown in Table 2. Figure 4 The average removal rate of nitrate nitrogen is 80.20%, which is 10.35% lower than that of example 2.

[0074] Control example 4

[0075] The same as example 1, except that the mass concentration of polyvinyl alcohol is 2%.

[0076] The filler prepared in this control example is used to remove nitrogen in the secondary biochemical effluent of a certain mixed sewage treatment plant in example 2. The results are shown in Table 2. Figure 5 The average removal rate of nitrate nitrogen is 65.82%.

[0077] Control example 5

[0078] Traditional filler (specific formula: sulfur and limestone filled in a volume ratio of 2:1) is used.

[0079] The filler prepared in this control example is used to remove nitrogen in the secondary biochemical effluent of a certain mixed sewage treatment plant in example 2. The results are shown in Table 2. Figure 6 The removal rate of nitrate nitrogen is 55.01%.

[0080] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A composite carrier packing material for enhanced sulfur autotrophic denitrification, characterized in that, It comprises a composite carrier and an encapsulated material; the composite carrier is composed of polyvinyl alcohol and biochar, and the encapsulated material is composed of riboflavin and denitrifying Pseudomonas aeruginosa. The preparation method of the enhanced sulfur autotrophic denitrification composite carrier packing includes the following steps: Polyvinyl alcohol is added to water and heated to 95-99℃ to make it a viscous liquid. It is then cooled to 25-35℃, biochar is added, and the mixture is sterilized and cooled to room temperature to obtain a composite carrier. Denitrifying Pseudomonas aeruginosa and riboflavin were added sequentially to the obtained composite carrier and stirred until homogeneous. The resulting mixture was then added dropwise to a cross-linking agent to react and obtain immobilized microspheres. These microspheres were then frozen, thawed, and air-dried to obtain a reinforced sulfur autotrophic denitrification composite carrier filler.

2. The enhanced sulfur autotrophic denitrification composite carrier packing according to claim 1, characterized in that, The polyvinyl alcohol comprises 4-6% by mass in the composite carrier, and the biochar comprises 1-2.5% by mass in the composite carrier.

3. The enhanced sulfur autotrophic denitrification composite carrier packing material according to claim 1, characterized in that, The riboflavin content in the embedded material is 1.5-3.5% by mass; the volume ratio of the denitrifying Pseudomonas aeruginosa to the composite carrier is 10:

1.

4. The enhanced sulfur autotrophic denitrification composite carrier packing according to claim 3, characterized in that, The method for culturing *Pseudomonas denitrificans* includes the following steps: inoculating *Pseudomonas denitrificans* into an enriched liquid culture medium and culturing it to obtain an enriched liquid bacterial solution, centrifuging it, and obtaining wet bacterial cells.

5. The enhanced sulfur autotrophic denitrification composite carrier packing according to claim 4, characterized in that, The enrichment liquid culture medium is prepared by mixing 5g sodium thiosulfate, 1g glucose, 0.01g ferrous chloride dodecahydrate, 2g potassium dihydrogen phosphate and 0.5g magnesium chloride hexahydrate; adjusting the pH of the system to 7.0, and sterilizing at high temperature to obtain the enrichment liquid culture medium.

6. The enhanced sulfur autotrophic denitrification composite carrier packing according to claim 1, characterized in that, The immobilized microspheres have a diameter of 3-5 mm; the crosslinking agent is an aqueous solution of calcium chloride, wherein the mass concentration of calcium chloride is 3%.

7. The enhanced sulfur autotrophic denitrification composite carrier packing according to claim 1, characterized in that, The freezing process involves freezing and storing the product at -20°C or below for 12-24 hours; the thawing and air-drying process involves thawing and air-drying at 0-3°C for 1-2 hours, followed by thawing and air-drying at room temperature for 6 hours.

8. The application of the enhanced sulfur autotrophic denitrification composite carrier packing material as described in any one of claims 1-7 in wastewater treatment, characterized in that, The reactor body used in the denitrification process is an upflow reactor. The reactor body consists of an inlet zone, a packing zone, and an outlet zone from bottom to top. The inlet zone is connected to the inlet system, and the outlet zone is connected to the outlet system. The packing zone is filled with the enhanced sulfur autotrophic denitrification composite carrier packing and sulfur.

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