Preparation method and application of composite autotrophic filter material for nitrogen removal, phosphorus removal and sulfur removal

Abstract

The invention discloses a preparation method and application of a composite denitrification, phosphorus removal and sulfur autotrophic filter material, relates to the technical field of sulfur autotrophic filter material, and comprises the following steps: stacking and combining a basic filter material, a catalyst-loaded filter material, a strain-heterojunction-loaded filter material, and a magnesium oxide microsphere filter material in a top-down order to obtain a composite denitrification, phosphorus removal and sulfur autotrophic filter material; in the stacking and combining process of the composite denitrification, phosphorus removal and sulfur autotrophic filter material, the stacking thickness ratio of the basic filter material: the catalyst-loaded filter material: the strain-heterojunction-loaded filter material: the magnesium oxide microsphere filter material is 10:(3-5):(2-4):(4-5). The invention develops an efficient and low-cost composite denitrification, phosphorus removal and sulfur autotrophic filter material for the coordinated governance needs of nitrogen and phosphorus pollution and PNP pollution.

Description

Technical Field

[0001] The invention relates to the technical field of sulfur autotrophic filter materials, in particular to a preparation method and application of a composite sulfur autotrophic filter material for denitrification and phosphorus removal. Background Art

[0002] Nitrate nitrogen (NO3 - -N) is one of the main causes of aquatic organism mortality and eutrophication. In order to effectively deal with this problem, various emerging technologies such as endogenous denitrification, iron (II) / manganese (II) oxidation-mediated denitrification and solid-state denitrification have been developed. However, compared with traditional physical and chemical treatment methods, these methods are often difficult to be widely used due to harsh conditions and high costs.

[0003] As an alternative, biological denitrification process has become an effective method for treating nitrate-containing wastewater due to its advantages such as low energy consumption and no secondary pollution. Biological denitrification is an important microbial-driven process in the nitrogen cycle. It achieves harmless treatment of pollutants by reducing nitrate-nitrogen to nitrogen gas (N2). However, the low carbon-nitrogen ratio (C / N<3) commonly found in wastewater significantly limits the efficiency of this process. Studies have shown that when C / N reaches 5, the denitrification effect can be significantly improved, approaching the ideal state of complete denitrification. Therefore, how to improve the denitrification efficiency under low C / N conditions has become a research hotspot in the field of wastewater treatment.

[0004] In addition, while controlling nitrogen pollution, the presence of trace organic pollutants (such as nitroaromatic compounds, NACs) in industrial wastewater has brought new challenges. NACs, represented by p-nitrophenol (PNP), have become common pollutants due to their wide application in military, pesticide, dye and pharmaceutical industries. PNP is acutely toxic, stubborn and mutagenic. Its pollution not only threatens the ecosystem, but also poses risks to public health, such as carcinogenesis, liver and kidney damage and blood diseases. Therefore, it is of great significance to develop efficient and low-cost composite autotrophic filter materials for nitrogen, phosphorus and sulfur removal in response to the coordinated control of nitrogen and phosphorus pollution and PNP pollution. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method and application of a composite autotrophic filter material for removing nitrogen, phosphorus and sulfur, so as to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a composite denitrification, phosphorus removal and sulfur removal autotrophic filter material, comprising the following steps: stacking and combining a basic filter material, a catalyst-loaded filter material, a strain-heterogeneous junction-loaded filter material, and a magnesium oxide microsphere filter material in a top-down order to obtain a composite denitrification, phosphorus removal and sulfur removal autotrophic filter material;

[0008] Furthermore, in the stacking and combination process of the composite denitrification, phosphorus removal and sulfur removal autotrophic filter material, the stacking thickness ratio of the basic filter material: the catalyst loaded filter material: the strain-heterogeneous junction loaded filter material: the magnesium oxide microsphere filter material is 10:(3-5):(2-4):(4-5);

[0009] Furthermore, the basic filter material is prepared by a hydrogel coating method using a granular adsorption medium prepared from water treatment residues, red mud, and elemental sulfur powder;

[0010] Furthermore, the catalyst-loaded filter material is prepared by immersing a sponge material in a mixed solution of ferric nitrate nonahydrate, manganese nitrate tetrahydrate, ammonium molybdate tetrahydrate, citric acid and deionized water through a citric acid-assisted impregnation method;

[0011] Furthermore, the sponge material is prepared from polyvinyl alcohol, chitosan and carboxymethyl cellulose;

[0012] Furthermore, the strain-heterogeneous junction loaded filter material is obtained by immersing the heterogeneous junction loaded filter material in a dual-carbon source culture medium containing Nocardia and Pseudomonas stutzeri and incubating the culture medium;

[0013] Furthermore, the heterojunction loaded filter material is prepared by pre-treating the sponge material with titanium tetrachloride, first reacting with tetrabutyl carbonate, and then embedding and calcining with urea.

[0014] Furthermore, the preparation method of the basic filter material includes the following steps: drying the water treatment residue at 80°C for 24 hours, grinding, and sieving to obtain residue powder; placing the residue powder in a 450-460°C environment for heat treatment for 4-5 hours to obtain heat-treated residue powder; adding the heat-treated residue powder to a 2% w / v sodium alginate solution, stirring at room temperature for 10-12 hours, adding a 2% w / v calcium chloride solution, stirring for reaction, filtering, and washing the solid product with deionized water to obtain a particulate adsorption medium; mixing the particulate adsorption medium, red mud and elemental sulfur powder evenly, adding a 2% w / v sodium alginate solution, stirring for reaction, adding a 2% w / v ferric chloride solution, filtering, soaking the solid product in the ferric chloride solution at room temperature for 4-6 hours, washing with deionized water, and drying at 45°C for 24 hours to obtain a basic filter material.

[0015] Furthermore, in the basic filter material, the mass ratio of particle adsorption grafting: red mud: elemental sulfur powder is 0.5:0.5:1.75.

[0016] Further, the water treatment residue is derived from any drinking water treatment plant that uses iron salts and aluminum salts as coagulants;

[0017] Furthermore, the specific elemental components of the water treatment residue of the present invention include: Fe 48.70%, Al 7.55%, Ca 21.68%, Si 17.23%, K 1.11%, P 0.26%, and the rest is S; the specific elemental components of the red mud include Fe 82.39%, Al 7.49%, Ca 1.03%, Si 2.02%, K 0.47%, P 0.20%, and the rest is S.

[0018] Furthermore, the preparation method of the strain-heterojunction loaded filter material comprises the following steps: step (1): adding polyvinyl alcohol to deionized water, stirring evenly, adding chitosan and carboxymethyl fiber, stirring evenly, adding a mixed solution consisting of 50% v / v formaldehyde solution, deionized water, and concentrated sulfuric acid, heating to 60-62° C. and reacting for 12 hours to obtain a sponge material; cutting the sponge material into small pieces and immersing them in a 0.1M titanium tetrachloride solution, stirring at room temperature for 20-30 minutes, taking out the 60° C. solution, and stirring at room temperature for 20-30 minutes. Dry for 30-45 minutes, repeat the immersion-drying process 3-5 times to obtain a pretreated sponge material; mix tetrabutyl titanate, deionized water, and hydrochloric acid evenly, add the pretreated sponge material, heat to 160-162°C to react for 12-14 hours, wash with anhydrous ethanol and deionized water, dry at 60°C for 2 hours, immerse in a supersaturated urea solution at room temperature for 2-3 hours, dry at 60°C for 2 hours, bury in urea and calcine at 550-555°C for 4 hours, wash, and dry to obtain a heterojunction loaded filter material;

[0019] Step (2): immerse the heterojunction-loaded filter material in a dual-carbon source culture medium containing Nocardia and Pseudomonas stutzeri, incubate for 2-3 days, replace with a fresh dual-carbon source culture medium and incubate again, repeat 4-5 times to obtain a strain-heterojunction-loaded filter material.

[0020] Furthermore, in the preparation process of the sponge material, the mass ratio of polyvinyl alcohol: chitosan: carboxymethyl cellulose is (8-10): (1-1.2): (5-6); in the preparation process of the heterojunction loaded filter material, the volume ratio of tetrabutyl titanate: deionized water: hydrochloric acid is 1:10:10.

[0021] Furthermore, the method for isolating Nocardia comprises the following steps:

[0022] Add 10g of reservoir sediment into the container, add dual carbon source culture medium, seal it, and culture it at 30℃. After 7 days, measure NO3 - Remove the supernatant, add fresh dual-carbon source medium, and repeat the operation until NO3 - The removal rates of -N and PNP were 90% and 60% respectively. Plates were plated and streaked. Gradient dilution plate method was used to isolate strains. The bacteria on the solid culture medium were transferred to the dual carbon source culture medium through an inoculation loop. After 3 days, NO3- -N, NO2 — N and PNP concentrations, the bacteria with the best removal effect are Nocardia used in the present invention.

[0023] Furthermore, the method for isolating Pseudomonas stutzeri comprises the following steps:

[0024] 10g of reservoir sediment was added into the container, enrichment medium was added, the container was sealed to ensure anaerobic environment, and cultured at 30℃. After 7 days, the denitrification effect was measured to obtain the mother liquor.

[0025] 10 mL of the mother solution was added to a low carbon-nitrogen ratio denitrification culture medium, and cultured at a constant temperature of 30° C. for 24 h. The nitrate concentration was measured, and the bacteria with the best removal effect were the Pseudomonas stutzeri used in the present invention.

[0026] The components of the enrichment culture medium include: 1g / L sodium acetate, 0.2g / L sodium nitrate, 0.1g / L dipotassium hydrogen phosphate, 0.05g / L magnesium chloride, 0.05g / L calcium chloride, and 2mL / L trace element solution; the components of the low carbon-nitrogen ratio depletion culture medium include: 0.146g / L sodium acetate, 0.152g / L sodium nitrate, 0.2g / L dipotassium hydrogen phosphate, 0.05g / L magnesium chloride, 0.05g / L calcium chloride, and 2mL / L trace element solution, and the carbon-nitrogen ratio is 2.0.

[0027] Furthermore, the concentration of Nocardia and Pseudomonas stutzeri is 10% v / v; the components of the dual-carbon source culture medium include: 0.1g / L sodium acetate, 0.1g / L sodium nitrate, 0.1g / L potassium dihydrogen phosphate, 0.05g / L magnesium sulfate, 0.05g / L calcium chloride, 4mL / LPNP standard solution, 2mL / L trace element solution; the concentration of the PNP standard solution is 5mg / mL; the components of the trace element solution include: 0.5g / L magnesium sulfate heptahydrate, 1g / LEDTA, 0.2g / L zinc nitrate, 0.1g / L manganese dichloride tetrahydrate, 0.5g / L ferrous sulfate heptahydrate, 0.5g / L copper sulfate pentahydrate, and 0.2g / L cobalt dichloride hexahydrate.

[0028] Furthermore, the preparation method of the catalyst-loaded filter material comprises the following steps: uniformly mixing tetrabutylphthalate, deionized water and hydrochloric acid, adding a pretreated sponge material, heating to 160-162° C. to react for 12-14 hours, washing with anhydrous ethanol and deionized water, drying at 60° C. for 2 hours, immersing at room temperature in a mixed solution consisting of ferric nitrate nonahydrate, manganese nitrate tetrahydrate, ammonium molybdate tetrahydrate, citric acid and deionized water, heating to 80-82° C. with stirring to remove deionized water, drying at 110-115° C. for 12 hours, and calcining at 500-505° C. for 5 hours to obtain a catalyst-loaded filter material.

[0029] Furthermore, in the preparation process of the catalyst-loaded filter material, the molar ratio of ferric nitrate nonahydrate, manganese nitrate tetrahydrate, ammonium molybdate tetrahydrate, citric acid:tetrabutylphthalate is 0.5:0.3:0.3:(0.03-0.05):10.

[0030] Furthermore, the preparation method of the magnesium oxide microsphere filter material comprises the following steps: adding aluminum nitrate hexahydrate, polyethylene glycol-2000, and sodium acetate to anhydrous ethanol, stirring evenly, heating to 180-185° C. to react for 6 hours, cooling, centrifugal filtering, washing the solid product with deionized water, drying at 60° C. for 8 hours, heating to 500-505° C. at a heating rate of 2° C. / min and calcining for 4 hours to obtain the magnesium oxide microsphere filter material.

[0031] Furthermore, in the preparation process of the magnesium oxide microsphere filter material, the mass ratio of aluminum nitrate hexahydrate: polyethylene glycol-2000: sodium acetate is (3.85-4):1:0.1.

[0032] A method for preparing a composite denitrification, phosphorus removal and sulfur autotrophic filter material, and application of the prepared composite denitrification, phosphorus removal and sulfur autotrophic filter material in the field of sewage denitrification and phosphorus removal.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention combines sulfur with a granular adsorption medium and red mud through a hydrogel encapsulation method to obtain two S-Fe cross-linked filling particles with a three-dimensional network structure. The amorphous iron in the granular adsorption medium is conducive to the enrichment of fermented rice bran and promotes the iron cycle of the system, thereby obtaining a more efficient and stable denitrification and phosphorus removal effect. The crystalline iron matrix in red mud can enhance the removal of nitrogen and phosphorus during sulfur autotrophic denitrification, and has the advantages of low sulfate production, small pH value effect, low energy consumption, and environmental protection. With the characteristics of low cost and high efficiency, it is used as the basic filter material for the composite denitrification and phosphorus removal sulfur autotrophic filter material, providing a guarantee for the denitrification and phosphorus removal performance of the composite denitrification and phosphorus removal sulfur autotrophic filter material.

[0035] 2. The present invention uses polyvinyl alcohol, carboxymethyl cellulose and chitosan as raw materials to prepare a hydrophilic sponge material carrier and construct a bioreactor. The purpose of using it as a carrier to perform titanium tetrachloride impregnation pretreatment is to ensure that the TiO2 seed layer is firmly fixed on the sponge material to prepare for subsequent reactions. The manganese-cobalt doped iron-titanium dioxide catalyst is prepared by citric acid-assisted impregnation method, and citric acid modification promotes Fe 2+ The effectiveness of the material formation, which has excellent low-temperature activity and photocatalytic performance, achieves the purpose of denitrification.

[0036] 3. The present invention uses the pretreated sponge material as a carrier to further prepare a TiO2 / C3N4 heterojunction structure, a new type of photocatalytic enhanced microbial system, for simultaneous algae removal and denitrification. The photocatalytic material and the active oxygen produced by the microorganisms work synergistically to improve the algae removal rate, while degrading the microcystins released by harmful algae, avoiding the secondary harm of traditional algae removal methods. On the basis of the existing denitrification system, the photocatalytic-microbial coupling system is additionally introduced to have higher denitrification efficiency and effective control of harmful algal blooms under natural light conditions, and the microbial community structure is optimized to improve the abundance of denitrifying colonies.

[0037] 4. The present invention introduces Nocardia for PNP denitrification degradation and Pseudomonas stutzeri for denitrification degradation on the basis of heterojunction loaded filter material. Different from the traditional sulfur autotrophic filter material, which needs to be rapidly enriched and cultivated for denitrification microbial flora before use, the use cost is reduced and the use steps are simplified. The introduction of Nocardia and Pseudomonas stutzeri cooperates with the previously constructed photocatalytic enhanced microbial system to maintain high metabolism and biological activity under low C / N conditions, and has excellent nitrogen removal and phosphorus removal performance.

[0038] 5. The present invention finally uses homemade magnesium oxide particles as a base to adsorb phosphorus pollution elements in sewage, and effectively removes phosphate in the aqueous solution through electrostatic attraction, ligand exchange, surface precipitation, sphere inner surface complexation and oxygen vacancy capture, thereby achieving the technical effect of phosphorus removal. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the following examples, polyethylene glycol-2000 was purchased from Yisheng Biotechnology, polyvinyl alcohol with a specification of 31000-50000 was purchased from Sigma-Aldrich, and the remaining raw materials were commercially available.

[0041] Embodiment 1: A method for preparing a composite autotrophic filter material for nitrogen removal, phosphorus removal and sulfur removal: S1: Dry the water treatment residue at 80°C for 24 hours, grind and sieve to obtain a residue powder; heat-treat the residue powder at 450°C for 4 hours to obtain a heat-treated residue powder; add the heat-treated residue powder to a 2% w / v sodium alginate solution, stir at room temperature for 10 hours, add a 2% w / v calcium chloride solution, stir to react, filter, and wash the solid product with deionized water to obtain a granular adsorption medium; mix the granular adsorption medium, red mud and elemental sulfur powder evenly, add a 2% w / v sodium alginate solution, stir to react, add a 2% w / v ferric chloride solution, filter, soak the solid product in the ferric chloride solution at room temperature for 4 hours, wash with deionized water, and dry at 45°C for 24 hours to obtain a basic filter material;

[0042] S2: Add 8g of polyvinyl alcohol to 100mL of deionized water, stir evenly, add 1g of chitosan and 5g of carboxymethyl fiber, stir evenly, add a mixed solution consisting of 5mL of 50% v / v formaldehyde solution, 20mL of deionized water, and 3mL of concentrated sulfuric acid, heat to 60°C and react for 12h to obtain a sponge material; cut the sponge material into small pieces and immerse it in a 0.1M titanium tetrachloride solution, stir at room temperature for 20min, take it out and dry it at 60°C for 30min, repeat the immersion-drying process 3 times to obtain a pretreated sponge material; mix 1mL of tetrabutyl titanate, 10mL of deionized water, and 10mL of hydrochloric acid evenly, add the pretreated sponge material, heat to 160°C and react for 12h, wash with anhydrous ethanol and deionized water, dry at 60°C for 2h, immerse it in a supersaturated urea solution at room temperature for 2h, dry it at 60°C for 2h, bury it in urea and calcine it at 550°C for 4h, wash it, and dry it to obtain a heterojunction loaded filter material;

[0043] S3: immersing the heterojunction-loaded filter material in a dual-carbon source culture medium containing Nocardia and Pseudomonas stutzeri, incubating for 2 days, replacing with a fresh dual-carbon source culture medium and incubating again, repeating 5 times to obtain a strain-heterogeneous junction-loaded filter material;

[0044] S4: 10 mmol of tetrabutylphthalate, deionized water and hydrochloric acid were mixed evenly, added to the pretreated sponge material, heated to 160°C for reaction for 12 h, washed with anhydrous ethanol and deionized water, dried at 60°C for 2 h, immersed in a mixed solution consisting of 5 mmol of ferric nitrate nonahydrate, 3 mmol of manganese nitrate tetrahydrate, 3 mmol of ammonium molybdate tetrahydrate, 0.03 mmol of citric acid and deionized water at room temperature, heated to 80°C with stirring to remove deionized water, dried at 110°C for 12 h, and calcined at 500°C for 5 h to obtain a catalyst-loaded filter material;

[0045] S5: Add 3.85 g aluminum nitrate hexahydrate, 1 g polyethylene glycol-2000, and 0.1 g sodium acetate to anhydrous ethanol, stir evenly, heat to 180° C. for 6 h, cool, centrifuge and filter, wash the solid product with deionized water, dry at 60° C. for 8 h, heat to 500° C. at a rate of 2° C. / min and calcine for 4 h to obtain magnesium oxide microsphere filter material;

[0046] S6: stack and combine the basic filter material, catalyst-loaded filter material, strain-heterogeneous junction-loaded filter material, and magnesium oxide microsphere filter material in order from top to bottom to obtain a composite autotrophic filter material for nitrogen removal, phosphorus removal, and sulfur removal.

[0047] In the stacking combination process of composite denitrification, phosphorus and sulfur removal autotrophic filter media, the stacking thickness ratio of basic filter media: catalyst loaded filter media: strain-heterojunction loaded filter media: magnesium oxide microsphere filter media is 10:3:2:4.

[0048] Example 2: A method for preparing a composite autotrophic filter material for nitrogen removal, phosphorus removal and sulfur removal: S4: 10mmol tetrabutylphthalate, deionized water and hydrochloric acid are mixed evenly, added to the pretreated sponge material, heated to 160°C for reaction for 12h, washed with anhydrous ethanol and deionized water, dried at 60°C for 2h, immersed in a mixed solution consisting of 5mmol ferric nitrate nonahydrate, 5mmol manganese nitrate tetrahydrate, 3mmol ammonium molybdate tetrahydrate, 0.03mmol citric acid and deionized water at room temperature, heated to 80°C with stirring to remove deionized water, dried at 110°C for 12h, and calcined at 500°C for 5h to obtain a catalyst-loaded filter material;

[0049] The remaining steps are the same as those in Example 1.

[0050] Example 3: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: During the stacking and combination process of the composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal, the stacking thickness ratio of the basic filter material: the catalyst-loaded filter material: the strain-heterojunction-loaded filter material: the magnesium oxide microsphere filter material is 10:4:3:5.

[0051] The remaining steps are the same as those in Example 2.

[0052] Example 4: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: During the stacking and combination process of the composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal, the stacking thickness ratio of the basic filter material: the catalyst loaded filter material: the strain-heterojunction loaded filter material: the magnesium oxide microsphere filter material is 10:5:4:5.

[0053] The remaining steps are the same as those in Example 2.

[0054] Comparative Example 1: A method for preparing a composite autotrophic filter material for nitrogen removal, phosphorus removal and sulfur removal: S4: 10mmol tetrabutylphthalate, deionized water and hydrochloric acid are mixed evenly, added to the pretreated sponge material, heated to 160°C for reaction for 12h, washed with anhydrous ethanol and deionized water, dried at 60°C for 2h, immersed in a mixed solution consisting of 5mmol ferric nitrate nonahydrate, 3mmol manganese nitrate tetrahydrate, 3mmol ammonium molybdate tetrahydrate and deionized water at room temperature, heated to 80°C, stirred to remove deionized water, dried at 110°C for 12h, and calcined at 500°C for 5h to obtain a catalyst-loaded filter material;

[0055] The remaining steps are the same as those in Example 1.

[0056] Comparative Example 2: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: S6: Stack and combine the basic filter material, the catalyst-loaded filter material and the magnesium oxide microsphere filter material in order from top to bottom to obtain a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal.

[0057] In the stacking combination process of composite denitrification, phosphorus and sulfur removal autotrophic filter material, the stacking thickness ratio of basic filter material: strain-heterogeneous junction load filter material: magnesium oxide microsphere filter material is 10:3:4.

[0058] The remaining steps are the same as those in Example 1.

[0059] Comparative Example 3: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: S6: Stack and combine the basic filter material, the strain-heterojunction loaded filter material, and the magnesium oxide microsphere filter material in order from top to bottom to obtain a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal.

[0060] In the stacking combination process of composite denitrification, phosphorus and sulfur removal autotrophic filter material, the stacking thickness ratio of basic filter material: strain-heterogeneous junction load filter material: magnesium oxide microsphere filter material is 10:2:4.

[0061] The remaining steps are the same as those in Example 1.

[0062] Comparative Example 4: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: S6: Stack and combine the basic filter material, catalyst-loaded filter material, and strain-heterojunction-loaded filter material in order from top to bottom to obtain a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal.

[0063] In the stacking combination process of composite denitrification, phosphorus and sulfur removal autotrophic filter material, the stacking thickness ratio of basic filter material: catalyst loaded filter material: strain-heterojunction loaded filter material is 10:3:2.

[0064] The remaining steps are the same as those in Example 1.

[0065] Comparative Example 5: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: S6: Stack and combine the basic filter material, catalyst-loaded filter material, strain-heterojunction-loaded filter material, and magnesium oxide microsphere filter material in order from top to bottom to obtain a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal.

[0066] In the stacking combination process of composite denitrification, phosphorus and sulfur removal autotrophic filter media, the stacking thickness ratio of basic filter media: catalyst loaded filter media: strain-heterogeneous junction loaded filter media: magnesium oxide microsphere filter media is 10:2:1:3.

[0067] The remaining steps are the same as those in Example 1.

[0068] Comparative Example 6: A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal: S6: Stack and combine the basic filter material, catalyst-loaded filter material, strain-heterojunction-loaded filter material, and magnesium oxide microsphere filter material in order from top to bottom to obtain a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal.

[0069] In the stacking and combination process of composite denitrification, phosphorus and sulfur removal autotrophic filter media, the stacking thickness ratio of basic filter media: catalyst loaded filter media: strain-heterogeneous junction loaded filter media: magnesium oxide microsphere filter media is 10:6:5:6.

[0070] The remaining steps are the same as those in Example 1.

[0071] Experiment: The experimental reactor material is organic glass, the inner diameter of the reactor is 50mm, the height of the reactor is 600mm, the effective solvent is 1L, and the reactor is filled with composite nitrogen removal, phosphorus removal and sulfur removal autotrophic filter material, with a filling rate of 30%; the peristaltic pump is used to control the hydraulic retention time (HRT), and the simulated wastewater is injected into the reactor, and the test is carried out after 30 days; the spectrophotometer is used to detect NO3 — N, PO4 3- -P changes, and liquid chromatography was used to detect the changes in PNP.

[0072] The HRT time was 6 h, the pH of the simulated wastewater was 6.5, and the low carbon-nitrogen ratio (C / N) was 2.0.

[0073] The components of the simulated wastewater used in the experiment include: 0.1g / L sodium nitrate, 0.1g / L dipotassium hydrogen phosphate, 0.05g / L magnesium sulfate, 0.05g / L calcium chloride, 2mL / L trace element solution, 0.1g / L sodium acetate, 4mL / LPNP, and 0.1g / L phosphoric acid.

[0074] The experimental data are shown in Table 1 below. The data in Table 1 do not reflect specific values ​​but only the removal rates before and after filtration. The removal rates are used to reflect the nitrogen removal and phosphorus removal performance of the sulfur autotrophic filter material.

[0075] Table 1 Sulfur autotrophic filter material nitrogen removal and phosphorus removal performance test data table

[0076] <![CDATA[N03 - N removal rate / %]]> <![CDATA[PO4 3- P removal rate / %]]> PNP removal rate / % Example 1 93.9 98.9 97.9 Example 2 95.6 98.9 98.2 Example 3 97.2 99.2 98.9 Example 4 98.4 99.5 99.4 Comparative Example 1 92.2 98.5 96.2 Comparative Example 2 91.8 97.8 91.0 Comparative Example 3 91.0 97.5 96.5 Comparative Example 4 93.5 88.7 97.8 Comparative Example 5 91.9 95.3 95.3 Comparative Example 6 94.0 98.8 97.9

[0077] Conclusion: The sulfur autotrophic filter material prepared by the present invention has excellent nitrogen and phosphorus removal performance.

[0078] In Comparative Example 1, citric acid was not used as a catalytic aid, resulting in a decrease in the denitrification and phosphorus removal performance of the sulfur autotrophic filter material; in Comparative Example 2, the strain-heterojunction loaded filter material was lacking, resulting in a decrease in the denitrification and phosphorus removal performance of the sulfur autotrophic filter material; in Comparative Example 3, the catalyst-loaded filter material was lacking, resulting in a decrease in the denitrification and phosphorus removal performance of the sulfur autotrophic filter material; in Comparative Example 4, the magnesium oxide microsphere filter material was lacking, resulting in a decrease in the phosphorus removal performance of the sulfur autotrophic filter material; in Comparative Example 5, the stacking thickness of the catalyst-loaded filter material, the strain-heterojunction loaded filter material, and the magnesium oxide microsphere filter material was reduced, resulting in a decrease in the denitrification and phosphorus removal performance of the sulfur autotrophic filter material; in Comparative Example 6, the stacking thickness of the catalyst-loaded filter material, the strain-heterojunction loaded filter material, and the magnesium oxide microsphere filter material was increased, and there was no obvious improvement in the denitrification and phosphorus removal performance of the sulfur autotrophic filter material, which wasted resources and was therefore discarded.

[0079] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal, characterized in that: The following steps are involved: The basic filter material, the catalyst-loaded filter material, the strain-heterogeneous junction-loaded filter material, and the magnesium oxide microsphere filter material are stacked and combined in order from top to bottom to obtain a composite autotrophic filter material for nitrogen removal, phosphorus removal, and sulfur removal; In the stacking and combination process of the composite denitrification, phosphorus and sulfur removal autotrophic filter material, the stacking thickness ratio of the basic filter material: the catalyst loaded filter material: the strain-heterogeneous junction loaded filter material: the magnesium oxide microsphere filter material is 10:(3-5):(2-4):(4-5); The basic filter material is prepared by a hydrogel coating method using a granular adsorption medium prepared from water treatment residues, red mud, and elemental sulfur powder; The catalyst-loaded filter material is prepared by immersing a sponge material in a mixed solution of ferric nitrate nonahydrate, manganese nitrate tetrahydrate, ammonium molybdate tetrahydrate, citric acid and deionized water through a citric acid-assisted impregnation method; The sponge material is prepared from polyvinyl alcohol, chitosan and carboxymethyl cellulose; The strain-heterogeneous junction loaded filter material is obtained by immersing the heterogeneous junction loaded filter material in a dual-carbon source culture medium containing Nocardia and Pseudomonas stutzeri for incubation; The heterojunction loaded filter material is prepared by pre-treating a sponge material with titanium tetrachloride, first reacting with tetrabutyl titanate, and then embedding and calcining with urea.

2. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 1, characterized in that: The preparation method of basic filter material comprises the following steps: drying, grinding and sieving water treatment residue to obtain residue powder; placing the residue powder in a 450-460 DEG C environment for heat treatment for 4-5 hours to obtain heat-treated residue powder; adding the heat-treated residue powder to a 2% w / v sodium alginate solution, stirring at room temperature, adding a 2% w / v calcium chloride solution, stirring for reaction, filtering, and washing a solid product with deionized water to obtain a particle adsorption medium; uniformly mixing the particle adsorption medium, red mud and elemental sulfur powder, adding a 2% w / v sodium alginate solution, stirring for reaction, adding a 2% w / v ferric chloride solution, filtering, soaking the solid product in the ferric chloride solution at room temperature, washing with deionized water, and drying to obtain a basic filter material.

3. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 1, characterized in that: The preparation method of a strain-heterogeneous junction loaded filter material comprises the following steps: step (1): adding polyvinyl alcohol to deionized water, stirring evenly, adding chitosan and carboxymethyl fiber, stirring evenly, adding a mixed solution consisting of 50% v / v formaldehyde solution, deionized water and concentrated sulfuric acid, heating to 60-62° C. and reacting for 12 hours to obtain a sponge material; cutting the sponge material into small pieces and immersing them in a 0.1M titanium tetrachloride solution, stirring at room temperature, taking them out and drying them, repeating the immersion-drying process 3-5 times to obtain a pretreated sponge material; mixing tetrabutyl titanate, deionized water and hydrochloric acid evenly, adding the pretreated sponge material, heating to 160-162° C. and reacting for 12-14 hours, washing with anhydrous ethanol and deionized water, drying, immersing them in a supersaturated urea solution at room temperature for 2-3 hours, drying, burying them in urea and calcining them at 550-555° C. for 4 hours, washing, and drying them to obtain a heterojunction loaded filter material; Step (2): immerse the heterojunction-loaded filter material in a dual-carbon source culture medium containing Nocardia and Pseudomonas stutzeri, incubate for 2-3 days, replace with a fresh dual-carbon source culture medium and incubate again, repeat 4-5 times to obtain a strain-heterojunction-loaded filter material.

4. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 3, characterized in that: In the preparation process of the sponge material, the mass ratio of polyvinyl alcohol: chitosan: carboxymethyl cellulose is (8-10): (1-1.2): (5-6); in the preparation process of the heterojunction loaded filter material, the volume ratio of tetrabutyl titanate: deionized water: hydrochloric acid is 1:10:

10.

5. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 3, characterized in that: The concentration of Nocardia and Pseudomonas stutzeri is 10% v / v; the components of the dual-carbon source culture medium include: 0.1g / L sodium acetate, 0.1g / L sodium nitrate, 0.1g / L potassium dihydrogen phosphate, 0.05g / L magnesium sulfate, 0.05g / L calcium chloride, 4mL / LPNP standard solution, 2mL / L trace element solution; the concentration of the PNP standard solution is 5mg / mL; the components of the trace element solution include: 0.5g / L magnesium sulfate heptahydrate, 1g / LEDTA, 0.2g / L zinc nitrate, 0.1g / L manganese dichloride tetrahydrate, 0.5g / L ferrous sulfate heptahydrate, 0.5g / L copper sulfate pentahydrate, and 0.2g / L cobalt dichloride hexahydrate.

6. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 1, characterized in that: Preparation method of catalyst-loaded filter material, The method comprises the following steps: uniformly mixing tetrabutyl titanate, deionized water and hydrochloric acid, adding a pretreated sponge material, heating to 160-162°C for reaction for 12-14 hours, washing with anhydrous ethanol and deionized water, drying, immersing in a mixed solution consisting of ferric nitrate nonahydrate, manganese nitrate tetrahydrate, ammonium molybdate tetrahydrate, citric acid and deionized water at room temperature, heating to 80-82°C, stirring to remove the deionized water, drying, and calcining at 500-505°C for 5 hours to obtain a catalyst-loaded filter material.

7. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 6, characterized in that: In the preparation process of the catalyst-loaded filter material, the molar ratio of hydrated ferric nitrate, tetrahydrated manganese nitrate, tetrahydrated ammonium molybdate, citric acid: tetrabutyl titanate is 0.5:0.3:0.3:(0.03-0.05):

10.

8. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 1, characterized in that: The preparation method of magnesium oxide microsphere filter material comprises the following steps: adding aluminum nitrate hexahydrate, polyethylene glycol-2000 and sodium acetate into anhydrous ethanol, stirring evenly, heating to 180-185° C. to react for 6 hours, cooling, centrifugal filtering, washing the solid product with deionized water, drying, and calcining at 500-505° C. for 4 hours to obtain magnesium oxide microsphere filter material.

9. The method for preparing a composite autotrophic filter material for denitrification, phosphorus removal and sulfur removal according to claim 8, characterized in that: In the preparation process of magnesium oxide microsphere filter material, the mass ratio of aluminum nitrate hexahydrate: polyethylene glycol-2000: sodium acetate is (3.85-4):1:0.

1.

10. Application of the composite denitrification, phosphorus removal and sulfur autotrophic filter material prepared by the method for preparing a composite denitrification, phosphorus removal and sulfur autotrophic filter material according to any one of claims 1 to 9 in the field of wastewater denitrification and phosphorus removal.