Preparation method of porous ceramic loaded sulfur-based composite filler and application of porous ceramic loaded sulfur-based composite filler in denitrification and dephosphorization of sewage

Abstract

This application relates to the field of wastewater treatment technology, and discloses a method for preparing porous ceramic-supported sulfur-based composite packing and its application in wastewater denitrification and phosphorus removal. Using porous ceramic as a carrier, a gradient filling process is employed to load active components in layers. The inner layer of siderite composite gel and calcite composite dynamically neutralizes the H+ generated by sulfur autotrophy. + pH buffering is achieved through reversible proton exchange of sulfonic acid groups; the middle-layer pyrite composite gel enhances compressive strength through C-O-Fe bonding, and the polypyrrole-coated hybrid gel constructs a π-π conjugated electron pathway, accelerating electron transfer and releasing Fe. 2+ Phosphate is precipitated; the outer layer of sulfur-biochar forms nano-sulfur crystals, rapidly initiating denitrification due to its high specific surface area. Sulfur consumption and sulfate accumulation are reduced through a sulfur-iron redox cycle. This packing material achieves highly efficient nitrogen and phosphorus removal from wastewater without the need for external carbon sources or pH adjusters.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, specifically to a method for preparing a porous ceramic-supported sulfur-based composite packing and its application in wastewater denitrification and phosphorus removal. Background Technology

[0002] In the field of wastewater treatment technology, nitrogen and phosphorus removal are core tasks for ensuring the ecological safety of water bodies. Traditional biological nitrogen removal relies on heterotrophic denitrification, which requires the addition of additional carbon sources (such as methanol and sodium acetate), increasing operating costs and easily causing secondary pollution. Chemical phosphorus removal involves adding iron or aluminum salts to form phosphate precipitation, but this consumes large amounts of reagents, produces high sludge yields, and the residual metal ions may negatively impact subsequent processes. The synergistic application of sulfur autotrophic denitrification and chemical precipitation for phosphorus removal is currently a research hotspot. Sulfur autotrophic denitrification uses sulfur as an electron donor to reduce nitrates, while chemical phosphorus removal relies on iron or aluminum salts to generate phosphate precipitation. However, existing technologies face two major challenges: First, the acidic environment (pH < 5.5) generated during sulfur autotrophic denitrification contradicts the neutral to slightly alkaline conditions required for chemical phosphorus removal, resulting in poor process stability and requiring frequent pH adjustments, increasing operational complexity. Second, traditional sulfur-iron composite packing materials suffer from low sulfur source utilization due to their simple structure, low specific surface area, and tendency for sulfur particles to clump together. Furthermore, when the concentration of sulfate generated by sulfur oxidation exceeds 300 mg / L, it inhibits microbial activity, further weakening denitrification efficiency. In addition, the packing material is prone to wear (annual wear rate > 5%) and structural disintegration, making long-term stable operation difficult and severely restricting the high efficiency and sustainable development of wastewater denitrification and phosphorus removal processes. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a method for preparing porous ceramic-supported sulfur-based composite fillers and their application in wastewater denitrification and phosphorus removal. Using porous ceramics as a carrier, a gradient filling process is employed to load active components in layers. The inner layer, a siderite composite gel and a calcite composite, dynamically neutralizes the H+ generated by sulfur autotrophy. + pH buffering is achieved through reversible proton exchange of sulfonic acid groups; the middle-layer pyrite composite gel enhances compressive strength through CO-Fe bonding, and the polypyrrole-coated hybrid gel constructs a π-π conjugated electronic pathway, accelerating electron transfer and releasing Fe. 2+ Phosphate is precipitated; the outer layer of sulfur-biochar forms nano-sulfur crystals, rapidly initiating denitrification due to its high specific surface area. Sulfur consumption and sulfate accumulation are reduced through a sulfur-iron redox cycle. This packing material achieves highly efficient nitrogen and phosphorus removal from wastewater without the need for external carbon sources or pH adjusters.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] In a first aspect, this application provides a method for preparing porous ceramic-supported sulfur-based composite fillers, comprising the following steps:

[0006] Sulfur was melted, mixed with rice husk biochar, and then vacuum impregnated and solidified to obtain a composite sulfur-carbon material.

[0007] A lignin sulfonic acid gel was prepared using a lignin sulfonic acid gel precursor solution containing iron ions, and a polypyrrole layer was coated on the surface of the lignin sulfonic acid gel to obtain a hybrid gel.

[0008] Pyrite powder and the hybrid gel are ultrasonically compounded to obtain pyrite composite gel; siderite powder and the hybrid gel are ball-milled to obtain siderite composite gel.

[0009] The mixed powder obtained by mixing the siderite composite gel with calcite powder is covered on the surface of a porous ceramic matrix, and the inner layer of porous ceramic is obtained by cold isostatic pressing; the pyrite composite gel is then filled into the inner layer of porous ceramic by vibration filling to obtain the middle layer of porous ceramic.

[0010] The middle layer of porous ceramic, the composite sulfur-carbon material and the lignin sulfonic acid gel precursor solution are mixed to obtain the outer layer of porous ceramic.

[0011] The outer layer of porous ceramic is subjected to gradient heat treatment and acid washing to obtain the porous ceramic-supported sulfur-based composite filler.

[0012] Secondly, this application provides a method for preparing porous ceramic-supported sulfur-based composite packing, and the application of the prepared porous ceramic-supported sulfur-based composite packing in wastewater denitrification and phosphorus removal.

[0013] Beneficial technical effects:

[0014] This method first prepares a porous ceramic matrix using clay, sawdust, and sodium silicate. Then, a gradient filling process is used to load active components in layers. The inner layer, a siderite composite gel and a calcite composite, continuously releases Fe. 2+ The process involves buffering the pH; a middle layer of pyrite composite gel constructs a high-speed electron transport pathway; and an outer layer of sulfur-biochar material rapidly releases electrons through nano-sulfur crystals to initiate denitrification. By introducing sodium lignosulfonate gel with a network structure, a uniform loading substrate is provided for polypyrrole. The resulting hybrid gel possesses a uniformly distributed π-π conjugated electron pathway, and the pH of the system can be adjusted by the sulfonic acid groups themselves, avoiding the impact of additional pH adjusters on the conjugated electron pathway and extending the service life of the uniformly distributed conjugated electron pathway. This scheme, through gradient loading, constructs a porous ceramic-supported sulfur-based composite packing material that achieves efficient nitrogen and phosphorus removal, low sulfate accumulation, and long service life in wastewater treatment without the addition of external carbon sources and pH adjusters. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the preparation method of the porous ceramic supported sulfur-based composite filler of the present invention.

[0016] Figure 2 This is a graph showing the trend of sulfate concentration change during 180 days of continuous operation of the porous ceramic-supported sulfur-based composite packing in wastewater denitrification and phosphorus removal application of Example 4 of the present invention. Detailed Implementation

[0017] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0018] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0019] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In a first aspect, this application provides a method for preparing porous ceramic-supported sulfur-based composite fillers, comprising the following steps:

[0022] Sulfur was melted, mixed with rice husk biochar, and then vacuum impregnated and solidified to obtain a composite sulfur-carbon material.

[0023] A lignin sulfonic acid gel was prepared using a lignin sulfonic acid gel precursor solution containing iron ions, and a polypyrrole layer was coated on the surface of the lignin sulfonic acid gel to obtain a hybrid gel.

[0024] Pyrite powder and the hybrid gel are ultrasonically compounded to obtain pyrite composite gel; siderite powder and the hybrid gel are ball-milled to obtain siderite composite gel.

[0025] The mixed powder obtained by mixing the siderite composite gel with calcite powder is covered on the surface of a porous ceramic matrix, and the inner layer of porous ceramic is obtained by cold isostatic pressing; the pyrite composite gel is then filled into the inner layer of porous ceramic by vibration filling to obtain the middle layer of porous ceramic.

[0026] The middle layer of porous ceramic, the composite sulfur-carbon material and the lignin sulfonic acid gel precursor solution are mixed to obtain the outer layer of porous ceramic.

[0027] The outer layer of porous ceramic is subjected to gradient heat treatment and acid washing to obtain the porous ceramic-supported sulfur-based composite filler.

[0028] A high-porosity porous ceramic matrix prepared from clay, sawdust, and sodium silicate was used as a carrier. Subsequently, an active component was loaded in layers using a gradient filling process. The inner layer, a siderite composite gel, was loaded with CO3 dissolved from calcite. 2- Dynamic neutralization of H generated by sulfur autotrophy + Meanwhile, the sulfonic acid group -SO3H in the hybrid gel achieves dynamic pH buffering through reversible proton exchange, stabilizing the pH of the system and avoiding the microbial inactivation problem caused by pH < 5.5 in traditional processes, thus extending the life of the packing material. The middle layer is a pyrite composite gel, and the hybrid gel and pyrite interface are chemically bonded by CO-Fe, which improves the compressive strength and reduces the risk of packing material wear. The outer layer of sulfur-biochar composite is formed into nano-sulfur crystals through liquid nitrogen quenching. The high specific surface area and high reactivity of nano-sulfur enable the denitrification reaction to start rapidly, increasing nitrate NO3. - -N removal rate. Furthermore, Fe removal via siderite and pyrite. 2+ / S 0 Redox cycles enable efficient electron utilization, and the slow release of Fe from siderite 2+ Oxidized to Fe 3+ Then, with S in sulfides 2- Regenerative Fe 2+ And generate elemental sulfur S 0 This forms a closed loop, which reduces sulfur consumption and lowers sulfate SO4 levels. 2- Concentration; the Fe(OH)3 colloid generated simultaneously and the hydroxyapatite Ca5(PO4)3OH enhance phosphorus removal through adsorption-coprecipitation, and the components work synergistically to achieve efficient nitrogen and phosphorus removal from wastewater.

[0029] In one feasible implementation, the rice husk biochar is obtained by pyrolyzing rice husks at 500-700℃ for 1.5-3 hours under a nitrogen atmosphere, and the mass ratio of the rice husk biochar to the sulfur is 1:(2-4); the vacuum impregnation time is 1-2 hours.

[0030] In one feasible implementation, the preparation method of the hybrid gel includes: preparing a 4-6 wt% sodium lignosulfonate solution, adding a 0.15-0.20 mol / L ferric chloride solution to a pH of 2.8-3.2 to obtain the sodium lignosulfonate gel precursor solution, and allowing it to stand for 10-12 h to obtain the lignosulfonic acid gel; mixing ethanol and water at a volume ratio of 1:1 to obtain a mixed solvent, and using the mixed solvent to prepare a 0.55-0.65 mol / L pyrrole solution; immersing the lignosulfonic acid gel in the pyrrole solution, introducing chlorine gas at a flow rate of 0.4-0.6 L / min, reacting at room temperature for 4-6 h, and then freeze-drying at -50°C for 4-6 h.

[0031] Sodium lignosulfonate gel via Fe 3+ The formation of a cross-linked network and the surface-coated polypyrrole layer construct π-π conjugated electron pathways, achieving the effect of inorganic sulfur donating electrons and organic hybrid gel transferring electrons, thereby enhancing the electron migration rate and simultaneously releasing Fe. 2+ It reacts with phosphate to form Fe3(PO4)2 precipitate, thereby improving the total phosphorus (TP) removal rate.

[0032] In one feasible implementation, the preparation method of the pyrite composite gel includes: adding 0.1wt%-0.12wt% of polyethylene glycol PEG-4000 to a mixture of pyrite powder and the hybrid gel at a mass ratio of (4-6):1, sonicating for 20-30 min, and vacuum drying at 60-80℃ for 12-24 h to obtain the pyrite composite gel; the preparation process of the siderite composite gel includes: mixing siderite powder and the hybrid gel at a mass ratio of (1.5-2.5):1, ball milling for 1-2 h, and heating at 100-120℃ for 30-60 min to obtain the siderite composite gel.

[0033] In one feasible implementation, the preparation method of the inner layer filled porous ceramic includes: mixing siderite composite gel and calcite powder at a mass ratio of (1.8-3):1 to obtain a mixed powder; spreading the porous ceramic matrix in a mold; uniformly spreading the mixed powder; the mass ratio of the porous ceramic matrix to the mixed powder is 1:(0.6-0.8); cold isostatic pressing at 8-10 MPa for 10-15 min; and gently brushing the surface with a soft brush to remove unbonded loose particles to obtain the inner layer filled porous ceramic.

[0034] In one feasible implementation, the preparation method of the middle layer filled porous ceramic includes: loading the pyrite composite gel and the inner layer filled porous ceramic into the hopper of a vibrating filler at a mass ratio of 1:(4-5), setting the amplitude to 25-30Hz and the vibration time to 20-30min, to obtain the middle layer filled porous ceramic.

[0035] In one feasible implementation, the preparation method of the outer layer filled porous ceramic includes: feeding the middle layer filled porous ceramic into a fluidized bed, introducing nitrogen gas, then feeding the preheated composite sulfur-carbon material to 60°C into the fluidized bed, atomizing the sodium lignosulfonate gel precursor liquid through a dual-fluid nozzle, and uniformly spraying it at a rate of 0.2-0.4 mL / min; immediately after spraying, turning on the liquid nitrogen cooling system to obtain the outer layer filled porous ceramic; the mass ratio of the middle layer filled porous ceramic, the composite sulfur-carbon material, and the sodium lignosulfonate gel precursor liquid is 8:(1-1.2):(0.2-0.4).

[0036] In one feasible implementation, the gradient heat treatment includes: placing the outer layer-filled porous ceramic into a programmable temperature-controlled furnace, heating it to 100-120℃ at a rate of 5-8℃ / min under a nitrogen atmosphere and holding it for 30-40 min, then heating it to 140-160℃ and holding it for 20-30 min, then heating it to 200-220℃ at a rate of 10℃ / min and holding it for 10-15 min, and finally cooling it to room temperature.

[0037] In one feasible implementation, the pickling process includes: placing the outer-filled porous ceramic that has undergone the gradient heat treatment into a drum reactor, while rotating it and spraying it with a 5-8 wt% citric acid solution, wherein the mass ratio of the citric acid solution to the outer-filled porous ceramic is (0.5-2):1, and drying it to obtain the porous ceramic-supported sulfur-based composite filler.

[0038] Secondly, this application provides a method for preparing porous ceramic-supported sulfur-based composite packing, and the application of the prepared porous ceramic-supported sulfur-based composite packing in wastewater denitrification and phosphorus removal.

[0039] The following will describe in detail, with reference to different embodiments, a method for preparing a porous ceramic-supported sulfur-based composite packing and its application in wastewater denitrification and phosphorus removal.

[0040] Example 1:

[0041] like Figure 1 As shown, a method for preparing a porous ceramic-supported sulfur-based composite filler includes the following steps:

[0042] 1. Mix 200-mesh clay, sawdust with a particle size ≤1mm and sodium silicate. The mass ratio of clay, sawdust and sodium silicate is 6:3:1. Form the mixture into particles with a diameter of 3mm using a screw extruder. Heat the mixture to 1100℃ at a rate of 10℃ / min and hold for 2 hours to obtain a porous ceramic matrix.

[0043] 2. After washing the rice husks, pyrolyze them at 500℃ for 3 hours under a nitrogen atmosphere, and pass them through a 200-mesh sieve to obtain rice husk biochar. Melt sulfur at 140℃ and mix it with the rice husk biochar at a mass ratio of 2:1. Vacuum impregnate for 1 hour and cool and solidify with liquid nitrogen to obtain composite sulfur-carbon material.

[0044] 3. Prepare a 4wt% sodium lignosulfonate solution, add 0.15mol / L ferric chloride solution to pH 2.8 to obtain a sodium lignosulfonate gel precursor solution, and let it stand for 10 h to obtain lignosulfonic acid gel; mix ethanol and water at a volume ratio of 1:1 to obtain a mixed solvent, and use the mixed solvent to prepare a 0.55mol / L pyrrole solution; immerse the lignosulfonic acid gel in the pyrrole solution, pass chlorine gas through it at a flow rate of 0.4L / min, react at room temperature for 4 h, wash with deionized water until neutral, and freeze-dry at -50℃ for 4 h to obtain a hybrid gel;

[0045] 4. Add 0.1 wt% polyethylene glycol PEG-4000 to a mixture of 200-mesh pyrite powder and the hybrid gel at a mass ratio of 4:1, sonicate at 40 kHz for 20 min, and vacuum dry at 60 °C for 24 h to obtain a pyrite composite gel; mix 100-mesh siderite powder and the hybrid gel at a mass ratio of 1.5:1, ball mill at 300 rpm for 1 h, and heat at 120 °C for 30 min to obtain a siderite composite gel;

[0046] 5. Mix siderite composite gel with 200-mesh calcite powder at a mass ratio of 1.8:1 to obtain a mixed powder. Spread the porous ceramic matrix in the mold and evenly sprinkle the mixed powder. The mass ratio of the porous ceramic matrix to the mixed powder is 1:0.6. Cold isostatically press under 8MPa pressure for 10min. Use a soft brush to gently sweep the surface to remove unbonded loose particles to obtain an inner layer filled with porous ceramic.

[0047] 6. Pyrite composite gel and inner layer filled porous ceramic are loaded into the hopper of a vibrating filler at a mass ratio of 1:4. The amplitude is set to 25Hz and the vibration time is 30min to obtain the middle layer filled porous ceramic.

[0048] 7. The porous ceramic intermediate layer is placed into a fluidized bed, and nitrogen gas is introduced at a flow rate of 0.8 m / s. Then, the composite sulfur-carbon material preheated to 60°C is added into the fluidized bed. The sodium lignosulfonate gel precursor liquid is atomized into 50 μm droplets through a dual-fluid nozzle at a flow rate of 0.2 m / s.

[0049] The coating is uniformly sprayed at a rate of mL / min. The mass ratio of the middle layer filled with porous ceramic, composite sulfur-carbon material and sodium lignosulfonate gel is 8:1:0.2. After the coating is completed, the liquid nitrogen cooling system is turned on immediately to obtain the outer layer filled with porous ceramic.

[0050] 8. The outer layer of porous ceramic is placed in a programmable temperature controlled furnace and heated to 100°C at 5°C / min under a nitrogen atmosphere. The temperature is held for 30 min, then further heated to 140°C and held for 20 min. The temperature is then increased to 200°C at 10°C / min and held for 10 min. After cooling to room temperature, the ceramic is placed in a drum reactor and rolled at a linear velocity of 0.5 m / s. At the same time, a 5 wt% citric acid solution is sprayed, with the mass ratio of the citric acid solution to the outer layer of porous ceramic being 0.5:1. After 2 h, the ceramic is washed with deionized water until neutral and then dried to obtain the porous ceramic-supported sulfur-based composite filler.

[0051] Example 2

[0052] like Figure 1 As shown, a method for preparing a porous ceramic-supported sulfur-based composite filler includes the following steps:

[0053] 1. Mix 200-mesh clay, sawdust with a particle size ≤1mm and sodium silicate. The mass ratio of clay, sawdust and sodium silicate is 6:3:1. Form the mixture into particles with a diameter of 3mm using a screw extruder. Heat the mixture to 1100℃ at a rate of 10℃ / min and hold for 2 hours to obtain a porous ceramic matrix.

[0054] 2. After washing the rice husks, pyrolyze them at 600℃ for 2 hours under a nitrogen atmosphere, and pass them through a 200-mesh sieve to obtain rice husk biochar. Then, melt sulfur at 140℃ and mix it with the rice husk biochar at a mass ratio of 3:1. Vacuum impregnate for 1.5 hours and cool and solidify with liquid nitrogen to obtain composite sulfur-carbon material.

[0055] 3. Prepare a 5wt% sodium lignosulfonate solution, add 0.18mol / L ferric chloride solution to pH 3.0 to obtain a sodium lignosulfonate gel precursor solution, and let it stand for 11 h to obtain lignosulfonic acid gel; mix ethanol and water at a volume ratio of 1:1 to obtain a mixed solvent, and use the mixed solvent to prepare a 0.6mol / L pyrrole solution; immerse the lignosulfonic acid gel in the pyrrole solution, pass chlorine gas through it at a flow rate of 0.5L / min, react at room temperature for 5 h, wash with deionized water until neutral, and freeze-dry at -50℃ for 5 h to obtain a hybrid gel;

[0056] 4. Mix 200-mesh pyrite powder with the hybrid gel at a mass ratio of 5:1, add 0.11wt% polyethylene glycol PEG-4000, sonicate at 40kHz for 25 min, and vacuum dry at 70℃ for 18 h to obtain pyrite composite gel; mix 100-mesh siderite powder with the hybrid gel at a mass ratio of 2:1, ball mill at 300rpm for 1.5 h, and heat at 110℃ for 45 min to obtain siderite composite gel;

[0057] 5. Mix siderite composite gel with 200 mesh calcite powder at a ratio of 2.4:1 to obtain a mixed powder. Spread the porous ceramic matrix in a mold and evenly sprinkle the mixed powder. The mass ratio of the porous ceramic matrix to the mixed powder is 1:0.7. Cold isostatically press under a pressure of 9 MPa for 12 min. Use a soft brush to gently sweep the surface to remove unbonded loose particles to obtain an inner layer filled with porous ceramic.

[0058] 6. Pyrite composite gel and inner layer filled porous ceramic are loaded into the hopper of a vibrating filler at a mass ratio of 1:4.5. The amplitude is set to 30Hz and the vibration time is 25min to obtain the middle layer filled porous ceramic.

[0059] 7. The porous ceramic layer is placed into a fluidized bed, and nitrogen gas with a flow rate of 0.8 m / s is introduced. Then, the composite sulfur-carbon material preheated to 60°C is placed into the fluidized bed. The sodium lignosulfonate gel precursor liquid is atomized into 50 μm droplets through a dual-fluid nozzle and sprayed uniformly at a rate of 0.3 mL / min. The mass ratio of the porous ceramic layer, the composite sulfur-carbon material, and the sodium lignosulfonate gel is 8:1.1:0.3. After the spraying is completed, the liquid nitrogen cooling system is immediately turned on to obtain the porous ceramic layer.

[0060] 8. The outer layer of porous ceramic is placed in a programmable temperature controlled furnace and heated to 110°C at 6°C / min under a nitrogen atmosphere. The temperature is held for 35 min, then further heated to 150°C and held for 25 min. The temperature is then increased to 210°C at 10°C / min and held for 15 min. After cooling to room temperature, the ceramic is placed in a drum reactor and rolled at a linear velocity of 0.5 m / s. At the same time, a 6 wt% citric acid solution is sprayed, with the mass ratio of the citric acid solution to the outer layer of porous ceramic being 1:1. After 2 h, the ceramic is washed with deionized water until neutral and then dried to obtain the porous ceramic-supported sulfur-based composite filler.

[0061] Example 3

[0062] like Figure 1 As shown, a method for preparing a porous ceramic-supported sulfur-based composite filler includes the following steps:

[0063] 1. Mix 200-mesh clay, sawdust with a particle size ≤1mm and sodium silicate, with a mass ratio of clay, sawdust and sodium silicate of 6:3:1. Form the mixture into particles with a diameter of 3mm using a screw extruder, heat it to 1100℃ at 10℃ / min, and hold it for 2 hours to obtain a porous ceramic matrix.

[0064] 2. After washing the rice husks, pyrolyze them at 700℃ for 1.5h under a nitrogen atmosphere, and pass them through a 200-mesh sieve to obtain rice husk biochar. Then, melt sulfur at 140℃ and mix it with the rice husk biochar at a mass ratio of 4:1. Vacuum impregnate for 2h and then cool and solidify with liquid nitrogen to obtain composite sulfur-carbon material.

[0065] 3. Prepare a 6wt% sodium lignosulfonate solution, add 0.20mol / L ferric chloride solution to pH 3.2 to obtain a sodium lignosulfonate gel precursor solution, and let it stand for 12h to obtain lignosulfonic acid gel; mix ethanol and water at a volume ratio of 1:1 to obtain a mixed solvent, and use the mixed solvent to prepare a 0.65mol / L pyrrole solution; immerse the lignosulfonic acid gel in the pyrrole solution, pass chlorine gas through it at a flow rate of 0.6L / min, react at room temperature for 6h, wash with deionized water until neutral, and freeze-dry at -50℃ for 6h to obtain a hybrid gel;

[0066] 4. Mix 200-mesh pyrite powder with the hybrid gel at a mass ratio of 6:1, add 0.12wt% polyethylene glycol PEG-4000, sonicate at 40kHz for 30 min, and vacuum dry at 80℃ for 12 h to obtain pyrite composite gel; mix 100-mesh siderite powder with the hybrid gel at a mass ratio of 2.5:1, ball mill at 300rpm for 2 h, and deheat at 100℃ for 60 min to obtain siderite composite gel;

[0067] 5. Mix siderite composite gel with 200 mesh calcite powder at a ratio of 3:1 to obtain a mixed powder. Spread the porous ceramic matrix in a mold and evenly sprinkle the mixed powder. The mass ratio of the porous ceramic matrix to the mixed powder is 1:0.8. Cold isostatically press under 10 MPa pressure for 15 min. Use a soft brush to gently sweep the surface to remove unbonded loose particles to obtain an inner layer filled porous ceramic.

[0068] 6. Pyrite composite gel and inner layer filled porous ceramic are loaded into the hopper of a vibrating filler at a mass ratio of 1:5. The amplitude is set to 30Hz and the vibration time is 20min to obtain the middle layer filled porous ceramic.

[0069] 7. The middle layer of porous ceramic is placed into a fluidized bed, and nitrogen gas with a flow rate of 0.8 m / s is introduced. Then, the composite sulfur-carbon material preheated to 60°C is placed into the fluidized bed. The sodium lignosulfonate gel precursor liquid is atomized into 50 μm droplets through a dual-fluid nozzle and sprayed uniformly at a rate of 0.4 mL / min. The mass ratio of the middle layer of porous ceramic, composite sulfur-carbon material and sodium lignosulfonate gel is 8:1.2:0.4. After the spraying is completed, the liquid nitrogen cooling system is immediately turned on to obtain the outer layer of porous ceramic.

[0070] 8. The outer layer of porous ceramic is placed in a programmable temperature controlled furnace and heated to 120°C at 8°C / min under a nitrogen atmosphere, held for 40 min, then heated to 160°C and held for 30 min, then heated to 220°C at 10°C / min and held for 15 min. After cooling to room temperature, it is placed in a drum reactor and rolled at a linear velocity of 0.5 m / s while spraying with an 8 wt% citric acid solution. The mass ratio of the citric acid solution to the outer layer of porous ceramic is 2:1. After 2 h, it is washed with deionized water until neutral and dried to obtain the porous ceramic-supported sulfur-based composite filler.

[0071] Example 4

[0072] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0073] The porous ceramic-supported sulfur-based composite packing prepared in Example 1 was packed into an upflow fixed bed with a filling rate of 60%. The influent water quality was: nitrate NO3. - -N=25mg / L, total phosphorus TP=3mg / L, pH=6.8, operating parameters: HRT=2h, backwash cycle 30 days; record effluent indicators and calculate removal rate, record packing life, the results are shown in Table 1.

[0074] Example 5

[0075] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0076] The implementation parameters and steps are the same as in Example 4. The difference from Example 4 is that the porous ceramic-supported sulfur-based composite packing of Example 1 is replaced with the porous ceramic-supported sulfur-based composite packing of Example 2.

[0077] Example 6

[0078] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0079] The implementation parameters and steps are the same as in Example 4. The difference from Example 4 is that the porous ceramic-supported sulfur-based composite packing of Example 1 is replaced with the porous ceramic-supported sulfur-based composite packing of Example 3.

[0080] Comparative Example 1

[0081] A method for preparing a porous ceramic-supported sulfur-based composite filler is described, with the same parameters and steps as in Example 1, except that no hybrid gel is added.

[0082] Comparative Example 2:

[0083] A method for preparing a porous ceramic-supported sulfur-based composite filler is implemented with the same parameters and steps as in Example 1, except that layered filling is not performed.

[0084] Comparative Example 3

[0085] A method for preparing a porous ceramic-supported sulfur-based composite filler is implemented with the same parameters and steps as in Example 1, except that siderite and pyrite are not added.

[0086] Comparative Example 4

[0087] A method for preparing a porous ceramic-supported sulfur-based composite filler is implemented with the same parameters and steps as in Example 1, except that a polypyrrole layer coating is not performed.

[0088] Comparative Example 5

[0089] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0090] The implementation parameters and steps are the same as in Example 4. The difference from Example 4 is that the porous ceramic-supported sulfur-based composite packing of Example 1 is replaced with the porous ceramic-supported sulfur-based composite packing of Comparative Example 1. The results are shown in Table 1.

[0091] Comparative Example 6

[0092] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0093] The implementation parameters and steps were the same as in Example 4. The difference from Example 4 was that the porous ceramic-supported sulfur-based composite packing of Example 1 was replaced with the porous ceramic-supported sulfur-based composite packing of Comparative Example 2. The results are shown in Table 1.

[0094] Comparative Example 7

[0095] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0096] The implementation parameters and steps were the same as in Example 4. The difference from Example 4 was that the porous ceramic-supported sulfur-based composite packing of Example 1 was replaced with the porous ceramic-supported sulfur-based composite packing of Comparative Example 3. The results are shown in Table 1.

[0097] Comparative Example 8

[0098] Application of a porous ceramic-supported sulfur-based composite packing material in wastewater denitrification and phosphorus removal.

[0099] The implementation parameters and steps are the same as in Example 4. The difference from Example 4 is that the porous ceramic-supported sulfur-based composite packing of Example 1 is replaced with the porous ceramic-supported sulfur-based composite packing of Comparative Example 4. The results are shown in Table 1.

[0100] Table 1. Results of nitrogen and phosphorus removal tests

[0101]

[0102]

[0103] As shown in Table 1, the porous ceramic-supported sulfur-based composite packing materials in Examples 4-6 effectively reduced NO3 in wastewater nitrogen and phosphorus removal tests. - -N removal rate ≥92.8%, TP removal rate ≥90.3%, SO4 removal rate ≥90.3%. 2- Accumulation ≤137mg / L, packing life up to 5 years. Comparative Examples 5-8 showed significantly reduced nitrogen and phosphorus removal efficiency, NO3... - -N removal rate <80.0%, TP removal rate <72.3%, SO4 removal rate <80.0%. 2- When the accumulation is ≥205mg / L, the packing life is significantly shortened compared to the example.

[0104] Performance testing:

[0105] The specific surface area of ​​the porous ceramic-supported sulfur-based composite fillers prepared in Examples 1-3 and Comparative Examples 1-4 was tested using BET according to ASTM D3663, and the results are shown in Table 2.

[0106] The sulfur loading rates of porous ceramic-supported sulfur-based composite fillers prepared according to ASTM E1019 using Test Examples 1-3 and Comparative Examples 1-4 are shown in Table 2.

[0107] The compressive strength of the porous ceramic-supported sulfur-based composite fillers prepared according to ISO 18591 in Examples 1-3 and Comparative Examples 1-4 is shown in Table 2.

[0108] According to atomic absorption spectrometry tests using EPA6010, the Fe content of porous ceramic-supported sulfur-based composite fillers prepared in Examples 1-3 and Comparative Examples 1-4 was measured. 2+ The sustained-release rate and results are shown in Table 2.

[0109] Table 2 Performance Test Results

[0110]

[0111]

[0112] As shown in Table 2, the porous ceramic-supported sulfur-based composite fillers prepared in Examples 1-3 have a specific surface area of ​​782-854 m². 2 / g, sulfur loading rate 34%~38%, compressive strength 9.94-12.71MPa, Fe 2+ The sustained-release rate was 0.12-0.17 mg / (g·d). Meanwhile, the porous ceramic-supported sulfur-based composite fillers prepared in Comparative Examples 1-4 had specific surface areas of 553-662 m². 2 / g, sulfur loading rate 20%–29%, compressive strength 5.33–8.46 MPa, Fe 2+ The sustained-release rate is 0.03-0.58 mg / (g·d).

[0113] In Comparative Examples 1 and 5, the porous ceramic-supported sulfur-based composite filler did not introduce hybrid gel. As shown in Tables 1 and 2, the denitrification and phosphorus removal efficiency decreased significantly, and NO3... - -N removal rate was 66.0%, TP removal rate was 60.0%, and packing life was shortened to 2 years. The hybrid gel made of lignin sulfonic acid gel and polypyrrole is the key medium for electron transfer. Without its introduction, the conductive network is missing, the electron migration rate is reduced, and sulfur autotrophic denitrification is hindered. At the same time, the dynamic pH regulation function of the sulfonic acid group of the gel is lost, which leads to system acidification, accelerates packing corrosion, and shortens life.

[0114] In Comparative Examples 2 and 6, the porous ceramic-supported sulfur-based composite filler was not layered, and NO3... - -N removal rate was 80.0%, but sulfate accumulation was high at 205 mg / L. The layered filling design—outer layer of sulfur-carbon material, middle layer of pyrite composite gel, and inner layer of calcite composite—achieves a synergistic effect through gradient electron release and pH buffering. Without layering, the mixing of components leads to excessively rapid sulfur oxidation and SO42---. 2- The accumulation of phosphorus increases, and the pH adjustment capacity is insufficient, resulting in an imbalance between denitrification and phosphorus removal efficiency.

[0115] In Comparative Examples 3 and 7, the porous ceramic-supported sulfur-based composite packings without the addition of siderite and pyrite resulted in a significant decrease in TP removal rate to 47.3%, and Fe... 2+ The slow-release rate is extremely low, only 0.03 mg / (g·d). Siderite and pyrite are Fe... 2+ The main source, Fe 2+ Phosphorus removal achieves a dual effect by generating FePO4 through chemical precipitation and catalytic sulfur oxidation, promoting electron transfer. Without this effect, phosphorus precipitation efficiency decreases, and sulfur autotrophic denitrification lacks a catalyst, thus limiting simultaneous nitrogen removal.

[0116] In Comparative Examples 4 and 8, the porous ceramic-supported sulfur-based composite fillers, which were not coated with a polypyrrole layer, exhibited a decrease in compressive strength to 8.46 MPa, a reduction in electron transport rate, and a decrease in Fe... 2+ The sustained-release rate was 0.37 mg / (g·d). The polypyrrole layer enhances the gel's conductivity through π-π conjugation; its absence leads to obstructed electron transport pathways, reduced interfacial bonding strength between pyrite and the gel, and decreased compressive strength. Fe... 2+ The reduced release rate affects the synergistic efficiency of phosphorus precipitation and sulfur oxidation reactions.

[0117] In addition, the filled upflow fixed bed from Example 4 was used for wastewater treatment and operated continuously for 180 days. The sulfate concentration changes were recorded every 15 days, and the results were as follows: Figure 2 As shown, the sulfate concentration in the effluent of the system of the present invention is stable at below 250 mg / L, which meets the requirements of the "Surface Water Environmental Quality Standard".

[0118] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0119] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A method for preparing a porous ceramic supported sulfur-based composite filler, characterized in that, Includes the following steps: Sulfur was melted, mixed with rice husk biochar, and then vacuum impregnated and solidified to obtain a composite sulfur-carbon material. Lignosulfonic acid gel was prepared using a lignin sulfonic acid gel precursor solution containing iron ions, and a polypyrrole layer was coated on the surface of the lignin sulfonic acid gel to obtain a hybrid gel. Pyrite powder and the hybrid gel are ultrasonically compounded to obtain pyrite composite gel; siderite powder and the hybrid gel are ball-milled to obtain siderite composite gel. The mixed powder obtained by mixing the siderite composite gel with calcite powder is covered on the surface of a porous ceramic matrix, and then cold isostatically pressed to obtain an inner layer of filled porous ceramic; the pyrite composite gel is then filled into the inner layer of filled porous ceramic by vibration filling to obtain a middle layer of filled porous ceramic. The middle layer of porous ceramic, the composite sulfur-carbon material and the lignin sulfonic acid gel precursor solution are mixed to obtain the outer layer of porous ceramic. The outer layer of porous ceramic is subjected to gradient heat treatment and acid washing to obtain the porous ceramic-supported sulfur-based composite filler. The preparation method of the hybrid gel includes: adding 0.15-0.20 mol / L ferric chloride solution to a 4-6 wt% sodium lignosulfonate solution until the pH is 2.8-3.2 to obtain the lignosulfonate gel precursor solution, and allowing it to stand for 10-12 h to obtain the lignosulfonate gel; mixing ethanol and water at a volume ratio of 1:1 to obtain a mixed solvent, and using the mixed solvent to prepare a 0.55-0.65 mol / L pyrrole solution; immersing the lignosulfonate gel in the pyrrole solution, introducing chlorine gas, reacting at room temperature for 4-6 h, and then freeze-drying at -50℃ for 4-6 h; The preparation method of the pyrite composite gel includes: adding 0.1wt%-0.12wt% of polyethylene glycol PEG-4000 to a mixture of pyrite powder and the hybrid gel at a mass ratio of (4-6):1, sonicating for 20-30 min, and vacuum drying at 60-80℃ for 12-24 h to obtain the pyrite composite gel; the preparation process of the siderite composite gel includes: mixing siderite powder and the hybrid gel at a mass ratio of (1.5-2.5):1, ball milling for 1-2 h, and heating at 100-120℃ for 30-60 min to obtain the siderite composite gel.

2. The method for preparing a porous ceramic-supported sulfur-based composite filler according to claim 1, characterized in that, The rice husk biochar is obtained by pyrolyzing rice husks at 500-700℃ for 1.5-3 hours under a nitrogen atmosphere, and the mass ratio of the rice husk biochar to the sulfur is 1:(2-4); the vacuum impregnation time is 1-2 hours.

3. The method for preparing a porous ceramic-supported sulfur-based composite filler according to claim 1, characterized in that, The preparation method of the inner layer filled porous ceramic includes: mixing siderite composite gel and calcite powder at a mass ratio of (1.8-3):1 to obtain a mixed powder; spreading the porous ceramic matrix in a mold; uniformly spreading the mixed powder; the mass ratio of the porous ceramic matrix to the mixed powder is 1:(0.6-0.8); cold isostatic pressing at 8-10 MPa for 10-15 min; and gently sweeping the surface with a soft brush to remove unbonded loose particles to obtain the inner layer filled porous ceramic.

4. The method for preparing a porous ceramic-supported sulfur-based composite filler according to claim 1, characterized in that, The preparation method of the middle layer filled porous ceramic includes: loading the pyrite composite gel and the inner layer filled porous ceramic into the hopper of a vibrating filler at a mass ratio of 1:(4-5), setting the amplitude to 25-30Hz and the vibration time to 20-30min, to obtain the middle layer filled porous ceramic.

5. The method for preparing a porous ceramic-supported sulfur-based composite filler according to claim 1, characterized in that, The preparation method of the outer layer filled porous ceramic includes: putting the middle layer filled porous ceramic into a fluidized bed, introducing nitrogen gas, then putting the composite sulfur-carbon material preheated to 60°C into the fluidized bed, atomizing the lignin sulfonic acid gel precursor liquid through a dual-fluid nozzle, and uniformly spraying it at a rate of 0.2-0.4 mL / min; immediately turning on the liquid nitrogen cooling system after spraying to obtain the outer layer filled porous ceramic; the mass ratio of the middle layer filled porous ceramic, the composite sulfur-carbon material and the lignin sulfonic acid gel precursor liquid is 8:(1-1.2):(0.2-0.4).

6. The method for preparing a porous ceramic-supported sulfur-based composite filler according to claim 1, characterized in that, The gradient heat treatment includes: placing the outer layer filled porous ceramic into a programmable temperature controlled furnace, heating it to 100-120℃ at 5-8℃ / min under a nitrogen atmosphere and holding it for 30-40min, continuing to heat it to 140-160℃ and holding it for 20-30min, then heating it to 200-220℃ at 10℃ / min and holding it for 10-15min, and finally cooling it to room temperature.

7. The method for preparing a porous ceramic-supported sulfur-based composite filler according to claim 1, characterized in that, The pickling process includes: putting the outer layer of porous ceramic that has undergone the gradient heat treatment into a drum reactor, while rolling and spraying 5-8wt% citric acid solution, with the mass ratio of citric acid solution to the outer layer of porous ceramic being (0.5-2):1, and drying to obtain the porous ceramic-supported sulfur-based composite filler.

8. The application of a porous ceramic-supported sulfur-based composite packing prepared by the preparation method according to any one of claims 1-7 in wastewater denitrification and phosphorus removal.

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