A molecular sieve functional filler for nitrogen and phosphorus removal in subsurface flow constructed wetlands

Abstract

The present invention relates to the technical field of environmental governance, and particularly relates to a molecular sieve functional filler for denitrification and dephosphorization in a subsurface flow constructed wetland. The preparation method thereof includes: placing natural zeolite, sodium hydroxide, lanthanum salt and aluminum salt in an ammonium bicarbonate solution, and carrying out a hydrothermal reaction under the conditions of 150-180 °C and 2-4 MPa to obtain the original powder of the molecular sieve functional filler. The present invention provides a method for preparing a molecular sieve functional filler with high added value by using cheap natural zeolite, abandons the traditional idea of using various functional fillers in a superposed composite structure, modifies the natural zeolite through a hydrothermal reaction to achieve the purpose of synchronous denitrification and dephosphorization, and significantly improves the denitrification and dephosphorization efficiency, providing a new idea for the technological innovation of new artificial wetland fillers. Moreover, the process of the present invention has the advantages of no secondary pollution, simple preparation process, short process flow and low cost, and has high application and popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental governance, and particularly relates to a molecular sieve functional filler for denitrification and dephosphorization in a subsurface flow constructed wetland. Background Art

[0002] The constructed wetland system belongs to an ecological engineering system and can be used for advanced sewage treatment, water body purification, non-point source pollution control, etc. The constructed wetland usually consists of multiple media such as a substrate, filler, plants, and microorganisms. Among them, the filler, as an important component and main carrier of the constructed wetland system, accounts for a relatively large proportion in the wetland system, especially in the subsurface flow wetland system. It can provide a matrix for plant growth, a carrier for microbial attachment, and a space for animal activities. In addition to adsorbing and intercepting pollutants such as nitrogen, phosphorus, chemical oxygen demand (COD), and heavy metals, the wetland filler can also reduce biodegradable pollutants through the created aerobic, anaerobic, and anoxic zones. The physical and chemical properties of the filler such as mechanical properties, permeability coefficient, particle size, and surface roughness have a direct impact on the pollution load and hydraulic load of the wetland and are important factors determining the sewage treatment effect.

[0003] The fillers widely used in existing constructed wetland projects are mainly natural minerals such as limestone, wollastonite, or pyrite, and industrial products such as slag or iron slag. Due to the small specific surface area and few adsorption sites of the material itself, they cannot effectively improve the removal effect of ammonia nitrogen inside the constructed wetland.

[0004] In addition, Patent No. 200810120258.X discloses a composite filler composed of clinoptilolite, red soil, and humus. The constructed wetland system using this composite filler has the ability to remove nitrogen; Patent No. 201320576702.5 uses polyvinyl alcohol gel and loofah sponge to solidify aerobic denitrifying bacteria to prepare a constructed wetland filler with pores of a polymer compound, achieving the purpose of improving the denitrification efficiency of the constructed wetland system; the above patents have effectively improved the removal of nitrogen in sewage by the constructed wetland, but have not solved the phosphorus removal problem at the same time.

[0005] Application No. 201110138826.0 discloses that a dewatered sludge device made of mineralized waste materials and Al salt coagulants is used to produce fillers with a particle size of 5-50 mm. By utilizing the characteristics of high Ca, Al, and Fe contents in the fillers, the removal effect of phosphorus in sewage is improved. Application No. 201320811962.6 uses a steel slag-furfural residue combined matrix as a composite matrix filler. The alkalinity of the steel slag can be alleviated by neutralizing with the acidity of the furfural residue, and the hydroxides generated by the reaction of calcium and magnesium compounds contained in the steel slag with water can modify the furfural residue to improve the adsorption capacity. The fillers used can greatly improve the phosphorus removal efficiency. Application No. 201410005588.X discloses that fly ash, gypsum, phosphogypsum, cement, aluminum powder, etc. are mixed to produce fillers, which have a good effect on the removal of phosphorus in sewage. Although the above patents solve the problem of phosphorus removal in wetland systems, they do not improve the nitrogen removal efficiency at the same time.

[0006] Sewage is often accompanied by a large number of complex pollutants such as ammonia nitrogen, phosphorus, organic matter, and heavy metals. Single-functional fillers can no longer meet the requirements of constructed wetlands. In summary, it is particularly urgent to provide a filler that can be used in subsurface flow constructed wetlands and can efficiently remove nitrogen and phosphorus at the same time. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a preparation method of a molecular sieve functional filler, including:

[0008] Put natural zeolite, sodium hydroxide, lanthanum salt, and aluminum salt into ammonium bicarbonate solution, and carry out hydrothermal reaction at 150-180 °C and 2-4 MPa to obtain the original powder of the molecular sieve functional filler.

[0009] The present invention uses inexpensive natural zeolite as the raw material, introduces Na element and La element through modification, enriches the Al content, and after hydrothermal reaction treatment under the above specific conditions, the natural zeolite molecular sieve undergoes hydrothermal recrystallization, and at the same time, three metal elements are loaded onto the natural zeolite molecular sieve, obtaining a molecular sieve functional filler with a high specific surface area and high purification efficiency, which can achieve the purpose of simultaneous nitrogen and phosphorus removal, and significantly improve the nitrogen and phosphorus removal efficiency. The preparation process is simple and the cost is controllable.

[0010] Although natural zeolite is widely used in constructed wetland fillers due to its rich variety and low price, its specific surface area is relatively low, only 20-40 m 2 / g, the adsorption capacity is small, and its performance varies due to different origins, and the stability of the adsorption effect cannot be guaranteed. The traditional modification methods cannot meet the current requirements for simultaneous removal of ammonia nitrogen, phosphorus, etc.

[0011] In the above-mentioned modification method of the present invention, sodium hydroxide can selectively remove silicon in the zeolite framework during the hydrothermal reaction, and aluminum chloride can supplement more aluminum elements, thereby reducing the silicon-aluminum ratio and increasing more acidity. The introduction of alkali metal cations in the system can improve the cation exchange capacity of the zeolite. At the same time, Na + ions are selected. Compared with traditional Ca 2+ ions, they are more conducive to improving the exchange capacity for NH4 + ions, thereby improving the ammonia nitrogen adsorption effect of the zeolite. At the same time, an inexpensive rare earth metal lanthanum is introduced in the present invention, and its purpose is to enhance the adsorption capacity for phosphate. Under hydrothermal reaction conditions, the lanthanum element can exist in an ionic state on the molecular sieve framework. When contacting with phosphate, on the one hand, the molecular sieve provides a relatively large specific surface area, which is conducive to forming a coordination with lanthanum to generate a stable complex. The large specific surface area can carry more adsorption space, thereby realizing the efficient removal of phosphate in water without affecting the ammonia nitrogen adsorption capacity of the material.

[0012] Under specific hydrothermal reaction conditions, a certain amount of ammonium bicarbonate is added. On the one hand, NH4 + ions can promote the restructuring of the natural zeolite framework, providing more framework-generated complex ions. On the other hand, ammonium bicarbonate will decompose into carbon dioxide microbubbles when heated. During the restructuring process of the natural zeolite unit cell, the aggregation of small particles is destroyed. By controlling the hydrothermal reaction conditions, the crystal grain growth rate can be controlled, thereby controlling the crystal grain size, so that the molecular sieve functional filler has a relatively large specific surface area.

[0013] As a preferred embodiment of the present invention, the heating rate of the hydrothermal reaction is controlled at 2-3 °C per minute.

[0014] The modification effect on natural zeolite is better when the hydrothermal reaction is carried out at the above heating rate.

[0015] As a preferred embodiment of the present invention, during the hydrothermal reaction process, the materials are stirred at a rate of 800-1200 revolutions per minute.

[0016] At the same time, when controlling the stirring speed and stirring time within the above range, it is more conducive to controlling the crystal grain growth rate, thereby controlling the crystal grain size, so that the molecular sieve functional filler has a larger specific surface area.

[0017] As a preferred embodiment of the present invention, the mass ratio of natural zeolite to sodium element, lanthanum element, and aluminum element is 100:1-5:1-4:10-20.

[0018] As a preferred embodiment of the present invention, the mass ratio of natural zeolite to ammonium bicarbonate is 100:10-20.

[0019] As a preferred embodiment of the present invention, the particle size of the natural zeolite is 260 to 300 mesh.

[0020] Preferably, the mass ratio of the natural zeolite to the water in the system is 100: 1000 to 1500.

[0021] As a preferred embodiment of the present invention, the lanthanum salt is at least one of lanthanum nitrate, lanthanum chloride, and lanthanum sulfate;

[0022] and / or, the aluminum salt is at least one of aluminum chloride, aluminum nitrate, and pseudo-boehmite.

[0023] In the specific implementation process, after the hydrothermal reaction is completed, the precipitate can be filtered and separated, and the molecular sieve functional material raw powder can be obtained after washing and drying.

[0024] As a preferred embodiment of the present invention, the preparation method further includes:

[0025] The molecular sieve functional filler raw powder, the auxiliary agent, and the biomass carbon are mixed in a mass ratio of 100: 10 to 25: 5 to 10 to obtain the molecular sieve functional filler.

[0026] In the specific implementation process, the molecular sieve functional filler raw powder, the auxiliary agent, and the biomass carbon can be mixed with water to form a mass, and then processed by extrusion molding through a mold. After being extruded into a porous structure, it can be applied.

[0027] In the specific implementation process, the mold used for extrusion molding is a seven-hole type, a honeycomb type, a daisy type, or a five-rib wheel type. Compared with traditional granular or block fillers, it can increase the liquid-solid contact area and improve the adsorption and purification efficiency. At the same time, it can reduce the water flow resistance, make the filler more regular, have high strength, avoid collapse, extend the service life of the molecular sieve functional filler, and is more suitable for use in constructed wetlands.

[0028] As a preferred embodiment of the present invention, the auxiliary agent is at least one of sesbania powder and cement powder; preferably, it is a mixture of sesbania powder and cement powder mixed in a mass ratio of 1: 2 to 10.

[0029] As a preferred embodiment of the present invention, the mass ratio of the molecular sieve functional material raw powder, the auxiliary agent sesbania powder, the auxiliary agent cement powder, and the biomass carbon is 100: 1 to 5: 10 to 20: 5 to 10.

[0030] In the specific implementation process, the biomass carbon includes, but is not limited to, rice husk powder, grass seeds, plant straw powder, or corn cob powder.

[0031] It has been found through research in the present invention that adding biomass carbon during the forming process can significantly increase the C / N ratio. Combining with the unique crystal structure of the molecular sieve which is conducive to surface dissolved oxygen, it can greatly improve the attachment ability of the filler to microorganisms, and is more helpful for improving the denitrification performance of the filler. While the modified zeolite has a good adsorption effect on ammonia nitrogen, the porous structure on the surface and inside can provide a habitat for microorganisms. Through the nitrification and denitrification processes of microorganisms, the ammonia nitrogen adsorbed by the zeolite filler is desorbed, thus regenerating the zeolite filler.

[0032] The auxiliary agent in the present invention can be selected as ordinary Portland cement. In the system of the present invention, the auxiliary agent can increase the filler density, making the density of the molecular sieve functional filler greater than the density of water, so that different types of constructed wetlands can be constructed according to actual situations, expanding the application scope; at the same time, the cement also plays a bonding role, which is beneficial to the stability of the overall structure of the filler, prolongs its service life, and ensures the realization of its various functions.

[0033] Furthermore, the present invention also provides the molecular sieve functional filler prepared by any of the above embodiments.

[0034] For the molecular sieve functional filler prepared in the present invention, compared with natural zeolite particles, its specific surface area is increased from 20 - 40 m 2 / g to 120 - 150 m 2 / g.

[0035] In addition, when the molecular sieve functional filler of the present invention is specifically used in a constructed wetland, to achieve better results, the nitrogen removal method is as follows: after film formation, the filler located in the anaerobic (dissolved oxygen is less than 0.2 mg / L) or anoxic (dissolved oxygen is 0.2 - 2.0 mg / L) area of the constructed wetland continuously purifies the polluted water for 24 - 48 h, and then the filler needs to be exposed to the air for at least 0.5 - 1.0 h before continuing to be used; or after film formation, it is used under the changing conditions of the dissolved oxygen range from anaerobic / anoxic to aerobic (greater than 2.0 mg / L).

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] The present invention provides a method for preparing a molecular sieve functional filler with high added value by using cheap natural zeolite, abandoning the traditional idea of superposing and compounding various functional fillers. Through hydrothermal reaction to modify natural zeolite, the purpose of synchronous nitrogen and phosphorus removal is achieved, and the nitrogen and phosphorus removal efficiency is significantly improved, providing a new idea for the technological innovation of new constructed wetland fillers. Moreover, the process of the present invention has the advantages of no secondary pollution, simple preparation process, short process, and low cost, and has high application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1These are three molds used in the preparation process of the molecular sieve functional filler of the present invention.

[0039] Figure 2 It is a graph showing the change of the adsorption capacity of the molecular sieve functional filler for ammonia nitrogen and total phosphorus with time. Detailed implementation mode

[0040] The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0041] For those not specifying specific techniques or conditions in the examples, they are all conventional methods or carried out according to the techniques or conditions described in the literature in this field, or according to the product specifications. For those reagents and instruments not indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0042] Example 1

[0043] This example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands, and the preparation method includes the following steps:

[0044] Step 1: Weigh 100 g of natural zeolite powder with a particle size of 260 - 300 mesh, wash it with deionized water and place it in a hydrothermal reaction kettle; weigh 1.74 g of sodium hydroxide, 2.34 g of lanthanum nitrate, and 49.39 g of aluminum chloride respectively, dissolve them in 100 g of deionized water, stir to prepare a mixed water-soluble salt solution and add it to the hydrothermal reaction kettle; weigh 10 g of ammonium bicarbonate and 1000 g of deionized water, add them to the hydrothermal reaction kettle respectively, and stir evenly with the previously added natural zeolite powder and the mixed water-soluble salt solution to form a mixed solution.

[0045] Step 2: After closing the hydrothermal reaction kettle, start the automatic stirring paddle, control the stirring speed at 800 revolutions per minute, start heating after adjusting the speed, increase the temperature of the solution in the hydrothermal reaction kettle to 150 °C at a heating rate of 2 - 3 °C per minute, maintain this temperature range, during which the pressure of the reaction kettle can be adjusted through the pressure relief valve, and the pressure of the reaction kettle is controlled at 2 - 3 MPa, and the reaction time is maintained for 5 hours. After the hydrothermal reaction is completed, cool it naturally to room temperature, open the reaction kettle, centrifuge and filter to obtain the precipitate, wash it 2 - 3 times with deionized water, and dry it in a constant temperature oven at 100 °C to obtain the modified molecular sieve functional filler raw powder.

[0046] Step 3: Weigh 100 g of the modified molecular sieve functional filler raw powder, 1 g of sesbania powder, 10 g of cement powder, and 5 g of corncob powder. After mechanical stirring evenly, add an appropriate amount of water and continue stirring. After forming into a dough shape, put it into an extruder for extrusion. Depending on the different molds, different shapes can be extruded, and at the same time, it is cut into the required length. The shape prepared in this example is a five-rib wheel shape, with the length controlled at 10 - 15 mm, the cylinder diameter being 12 mm. After drying in a hot air oven at 120 °C, the molecular sieve functional filler is finally obtained.

[0047] Example 2

[0048] This example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands. The preparation method includes the following steps:

[0049] Step 1: Weigh 100 g of natural zeolite powder with a particle size of 260 - 300 mesh. After washing with deionized water, place it in a hydrothermal reaction kettle; weigh 8.70 g of sodium hydroxide, 9.36 g of lanthanum nitrate, and 98.77 g of aluminum chloride respectively, dissolve them in 200 g of deionized water, stir to prepare a mixed water-soluble salt solution and add it to the hydrothermal reaction kettle; weigh 20 g of ammonium bicarbonate and 1500 g of deionized water, and add them to the hydrothermal reaction kettle respectively, and stir evenly with the previously added natural zeolite powder and the mixed water-soluble salt solution to form a mixed solution.

[0050] Step 2: After closing the hydrothermal reaction kettle, start the automatic stirring paddle, control the stirring speed at 1200 revolutions per minute. After adjusting the speed, start heating up at a heating rate of 2 - 3 °C per minute until the solution temperature in the hydrothermal reaction kettle reaches 180 °C, and maintain this temperature range. During this period, the pressure of the reaction kettle can be adjusted through the pressure relief valve, and the reaction kettle pressure is controlled at 3.5 - 4 MPa. The reaction time is maintained for 8 hours. After the hydrothermal reaction is completed, naturally cool to room temperature. After opening the reaction kettle, centrifuge and filter to obtain the precipitate, wash it 2 - 3 times with deionized water, and dry it in a constant temperature oven at 100 °C to obtain the modified molecular sieve functional filler raw powder.

[0051] Step 3: Weigh 100 g of the modified molecular sieve functional filler raw powder, 5 g of sesbania powder, 20 g of cement powder, and 10 g of corncob powder. After mechanical stirring evenly, add an appropriate amount of water and continue stirring. After forming into a dough shape, put it into an extruder for extrusion. Depending on the different molds, different shapes can be extruded, and at the same time, it is cut into the required length. The shape in this example is a five-rib wheel shape, with the length controlled at 10 - 15 mm, the cylinder diameter being 12 mm. After drying in a hot air oven at 120 °C, the molecular sieve functional filler is finally obtained.

[0052] Example 3

[0053] This embodiment provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands, and the preparation method includes the following steps:

[0054] Step 1: Weigh 100 g of natural zeolite powder with a particle size of 260 - 300 mesh, wash it with deionized water and place it in a hydrothermal reaction kettle; weigh 5.50 g of sodium hydroxide, 6.00 g of lanthanum nitrate, and 70.00 g of aluminum chloride respectively, dissolve them in 200 g of deionized water, stir to prepare a mixed water-soluble salt solution and add it to the hydrothermal reaction kettle; weigh 15 g of ammonium bicarbonate and 1200 g of deionized water, add them to the hydrothermal reaction kettle respectively, and stir evenly with the previously added natural zeolite powder and mixed water-soluble salt solution to form a mixed solution.

[0055] Step 2: After sealing the hydrothermal reaction kettle, start the automatic stirring paddle, control the stirring speed between 1000 revolutions per minute, start heating after adjusting the speed, and increase the temperature of the solution in the hydrothermal reaction kettle to 160 °C at a heating rate of 2 - 3 °C per minute. Keep this temperature range. During this period, the pressure of the reaction kettle can be adjusted through the pressure relief valve, and the pressure of the reaction kettle is controlled at 3 - 3.5 MPa. The reaction time is maintained for 7 hours. After the hydrothermal reaction is completed, naturally cool it to room temperature. After opening the reaction kettle, centrifuge, separate and filter to obtain a precipitate, wash it 2 - 3 times with deionized water, and dry it in a constant temperature oven at 100 °C to obtain the original powder of the modified molecular sieve functional filler.

[0056] Step 3: Weigh 100 g of the original powder of the modified molecular sieve functional filler, 5 g of sesbania powder, 15 g of cement powder, and 8 g of corncob powder, stir evenly mechanically, add an appropriate amount of water, continue to stir, and put it into an extruder for extrusion after forming into a mass. Depending on the different molds, different shapes can be extruded, and at the same time, cut into the required length. The shape of this embodiment is a five-rib wheel type, the length is controlled at 10 - 15 mm, the cylinder diameter is 12 mm, and after drying in a hot air oven at 120 °C, the molecular sieve functional filler is finally obtained.

[0057] Example 4

[0058] This embodiment provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands, and the preparation method includes the following steps:

[0059] Step 1: Weigh 100 g of natural zeolite powder with a particle size of 260 - 300 mesh, wash it with deionized water and place it in a hydrothermal reaction kettle; weigh 1.74 g of sodium hydroxide, 9.36 g of lanthanum nitrate, and 70.00 g of aluminum chloride respectively, dissolve them in 200 g of deionized water, stir to prepare a mixed water-soluble salt solution and add it to the hydrothermal reaction kettle; weigh 10 g of ammonium bicarbonate and 1500 g of deionized water, add them to the hydrothermal reaction kettle respectively, and stir evenly with the previously added natural zeolite powder and mixed water-soluble salt solution to form a mixed solution.

[0060] Step 2: After sealing the hydrothermal reaction kettle, start the automatic stirring paddle, control the stirring speed between 1200 revolutions per minute. After adjusting the speed, start heating up at a heating rate of 2 - 3 °C per minute until the solution temperature in the hydrothermal reaction kettle reaches 150 °C. Maintain this temperature range. During this period, the pressure of the reaction kettle can be adjusted through the pressure relief valve, and the pressure of the reaction kettle is controlled at 3.0 - 3.5 MPa. The reaction time is maintained for 8 hours. After the hydrothermal reaction is completed, naturally cool it to room temperature. After opening the reaction kettle, centrifuge, separate, and filter to obtain the precipitate, wash it with deionized water 2 - 3 times, and dry it in a constant temperature oven at 100 °C to obtain the original powder of the modified molecular sieve functional filler.

[0061] Step 3: Weigh 100 g of the original powder of the modified molecular sieve functional filler, 5 g of sesbania powder, 10 g of cement powder, and 8 g of corn cob powder. After mechanically stirring evenly, add an appropriate amount of water and continue stirring. After forming into a dough-like shape, put it into an extruder for extrusion. Depending on the different molds, different shapes can be extruded, and at the same time, cut it into the required length. The shape of this embodiment is a five-rib wheel type, the length is controlled at 10 - 15 mm, the cylinder diameter is 12 mm, and after drying in a hot air oven at 120 °C, the molecular sieve functional filler is finally obtained.

[0062] Example 5

[0063] This example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands. The only difference in the preparation method from Example 3 is that the corn cob powder is replaced with rice husk powder.

[0064] Comparative Example 1

[0065] This comparative example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands. The only difference in the preparation method from Example 3 is that sodium hydroxide is replaced with calcium hydroxide.

[0066] Comparative Example 2

[0067] This comparative example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands. The only difference in the preparation method from Example 3 is that aluminum chloride is replaced with ferric chloride.

[0068] Comparative Example 3

[0069] This comparative example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands. The only difference in the preparation method from Example 3 is that ammonium bicarbonate is replaced with ammonia water.

[0070] Comparative Example 4

[0071] This comparative example provides a molecular sieve functional filler for denitrification and dephosphorization in subsurface flow constructed wetlands. The only difference in the preparation method from Example 3 is that the pressure of the hydrothermal reaction kettle is controlled at atmospheric pressure.

[0072] Test Example 1

[0073] Ammonia nitrogen and phosphorus removal experiments were carried out on the molecular sieve functional fillers prepared in the above-mentioned examples and comparative examples. The specific method was as follows:

[0074] The molecular sieve functional fillers prepared in the examples and comparative examples were packed into columns. The cross-sectional diameter of the column was 10 cm, and the packing height was 50 cm. The influent DO was controlled at 4.2 - 4.6 mg·L -1 , the temperature was at 30 ± 1 °C, the influent pH was 6.5, and the flow rate was 3 ml / min. Different packing columns were used to treat the influent water quality, and the results are shown in Table 1.

[0075] Table 1 Test Results

[0076]

[0077]

[0078] As can be seen from Table 1, the molecular sieve functional filler prepared by the present invention has excellent purification effects on nitrogen and phosphorus. When treating TOC, ammonia nitrogen and total phosphorus in sewage, the purification efficiency of TOC is 87.5% - 90.54%, the purification efficiency of ammonia nitrogen is 88.28% - 93.23%, the purification efficiency of nitrate nitrogen is 94.8% - 96.86%, the purification efficiency of total nitrogen is 89.38% - 91.13%; the purification efficiency of total phosphorus is 93.86% - 96.16%.

[0079] Comparative Examples 1 - 3 could not achieve the excellent treatment effect of efficiently treating TOC, ammonia nitrogen and total phosphorus simultaneously, indicating that there is a synergistic effect among sodium hydroxide, aluminum salt and ammonium bicarbonate in the technical solution of the present invention. In Comparative Example 4, due to the failure to control the appropriate hydrothermal reaction pressure, although the natural zeolite molecular sieve was loaded with metal elements such as Na, La and Al, the recrystallization process of the natural zeolite molecular sieve was not achieved, resulting in poor filler performance.

[0080] Test Example 2

[0081] The specific surface area of the molecular sieve functional fillers prepared in the above-mentioned examples and comparative examples was tested, and the results are shown in Table 2.

[0082] Table 2 Specific Surface Area of Molecular Sieve Functional Filler

[0083] Sample <![CDATA[Specific surface area m 2 / g]]> Sample <![CDATA[Specific surface area m 2 / g <!-- 7 -->]]> Example 1 140 Comparative Example 1 66 Example 2 142 Comparative Example 2 65 Example 3 138 Comparative Example 3 45 Example 4 140 Comparative Example 4 31 Example 5 150

[0084] Through test comparison, the specific surface area of the molecular sieve functional filler in the example increased significantly, which also promoted the adsorption capacity of the molecular sieve functional filler for ammonia nitrogen and total phosphorus.

[0085] Test Example 3

[0086] Taking the molecular sieve functional filler in Example 3 as an example, the curves of the adsorption capacity of the molecular sieve functional filler for ammonia nitrogen and total phosphorus varying with time were measured, and the results are as Figure 2 shown.

[0087] Among them, a control group was set for comparison. The preparation method of the filler in the control group was as follows:

[0088] Weigh 100 g of natural zeolite raw powder, 5 g of sesbania powder, 15 g of cement powder, and 8 g of corncob powder. After mechanical stirring, add an appropriate amount of water and continue stirring. After forming into a dough, put it into an extruder for extrusion. Depending on the different molds, different shapes can be extruded, and at the same time, cut into the required length. The shape of the control group is a five-rib wheel type, the length is controlled at 10 - 15 mm, the cylinder diameter is 12 mm, and after drying in a hot air oven at 120 °C, the final formed filler is obtained.

[0089] It can be Figure 2 seen that the adsorption capacities of ammonia nitrogen and total phosphorus increase with time. The process of 0 - 200 seconds is the rapid adsorption process of ammonia nitrogen and total phosphorus by the molecular sieve functional filler. About 6.5 mg / g of ammonia nitrogen and 3.8 mg / g of total phosphorus can be adsorbed by 100 g of the molecular sieve functional filler within 200 seconds. After 400 seconds, the adsorption amount of the molecular sieve functional filler increases slowly and basically reaches the adsorption equilibrium stage. The maximum equilibrium adsorption amount is 7.0 mg / g for ammonia nitrogen and 4.0 mg / g for total phosphorus. It can be seen that the molecular sieve functional filler of the present invention has a very fast and high adsorption capacity for ammonia nitrogen and total phosphorus. Compared with the control group, it is found that the traditional natural zeolite filler has a certain adsorption capacity for ammonia nitrogen, but it is very low, and almost no adsorption capacity for total phosphorus.

[0090] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A preparation method of a molecular sieve functional filler, characterized in that, Including: Put natural zeolite, sodium hydroxide, lanthanum salt and aluminum salt into ammonium bicarbonate solution, and carry out hydrothermal reaction at 150 - 180 °C and 2 - 4 MPa to obtain the original powder of molecular sieve functional filler; mix the original powder of molecular sieve functional filler with an auxiliary agent and biomass carbon according to a mass ratio of 100:10 - 25:5 - 10 to obtain the molecular sieve functional filler; the auxiliary agent is a mixture of sesbania powder and cement powder mixed according to a mass ratio of 1:2 - 10; the biomass carbon is rice husk powder.

2. The preparation method according to claim 1, wherein, The heating rate of the hydrothermal reaction is controlled at 2 - 3 °C per minute.

3. The preparation method according to claim 1 or 2, characterized in that, During the hydrothermal reaction process, stir the materials at a rate of 800 - 1200 revolutions per minute for 5 - 8 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The mass ratio of natural zeolite to sodium element, lanthanum element, and aluminum element is 100:1 - 5:1 - 4:10 - 20.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The mass ratio of natural zeolite to ammonium bicarbonate is 100:10 - 20.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The particle size of natural zeolite is 260 - 300 mesh.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The lanthanum salt is at least one of lanthanum nitrate, lanthanum chloride, and lanthanum sulfate; And / or, the aluminum salt is at least one of aluminum chloride, aluminum nitrate, and pseudo-boehmite.

8. A molecular sieve functional filler, characterized in that, It is prepared by the preparation method described in any one of claims 1 - 7.

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