Composite filler, preparation method of composite filler and constructed wetland repair filler layer

Abstract

The invention provides a composite filler, a preparation method of the composite filler and a constructed wetland repair filler layer. The composite filler is mainly prepared from the following raw materials in parts by mass: 20 to 40 parts of combined polyether, 0.005 to 0.02 part of anaerobic ammonium oxidation bacteria, 0.005 to 0.02 part of solid nitrifying bacteria, 0.005 to 0.02 part of biological enzyme, 1 to 3 parts of iron powder, 1 to 7 parts of pyrite powder, 1 to 3 parts of carbon black, 10 to 20 parts of foaming agent, 30 to 50 parts of isocyanate and 3 to 10 parts of loading filler. The composite filler has better nitrogen and phosphorus removal capacity and heavy metal ion pollution removal capacity.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial wetland restoration, and in particular to a composite filler, a preparation method of the composite filler, and an artificial wetland restoration filler layer. Background Art

[0002] Constructed wetlands are complex systems composed of a filler matrix, plants, and microorganisms. Sewage and sludge are dosed into the system in a controlled manner. As the sewage and sludge flow in a specific direction, they are treated primarily through the synergistic physical, chemical, and biological effects of soil, artificial media, plants, and microorganisms. They achieve efficient purification of pollutants through filtration, adsorption, co-precipitation, ion exchange, plant absorption, and microbial decomposition. Furthermore, through the biogeochemical cycle of nutrients and water, they promote the growth of green plants and increase their production, ultimately achieving resource utilization and harmlessness of wastewater.

[0003] Filler matrix, commonly referred to as filter media, is a core component of constructed wetlands. Based on their source and purpose, it can be categorized as natural materials, industrial byproducts, man-made products, and combinations. Its primary function is to provide support and a nutrient environment for the roots of wetland plants and microbial communities, fostering diverse biochemical processes within the ecosystem and removing pollutants from the water. However, existing filler matrices are insufficiently capable of removing nitrogen, phosphorus, and heavy metal ions, hindering the water purification capabilities of constructed wetlands.

[0004] In view of this, this invention is proposed. Summary of the Invention

[0005] The first purpose of the present invention is to provide a composite filler with excellent physical and chemical properties. When the composite filler is applied to artificial wetlands, it can significantly improve the denitrification and phosphorus removal capabilities and the ability to remove heavy metal ion pollution, thereby significantly improving water quality and purifying the Class A tail water quality of urban sewage treatment plants to surface water quality levels of Class IV to Class V.

[0006] The second object of the present invention is to provide a method for preparing the composite filler, which is simple to operate and highly efficient.

[0007] The third object of the present invention is to provide a method for preparing the above-mentioned composite filler, which can significantly improve the activity of microorganisms through distributed operation, thereby improving the physical and chemical properties of the composite filler and its sewage treatment capacity.

[0008] The fourth purpose of the present invention is to provide an artificial wetland restoration filler layer, which has good sewage treatment capabilities and can effectively remove nitrogen, phosphorus and heavy metal ions in sewage. It is applied to sewage treatment processes in scenarios such as urban sewage treatment plants. It can purify the first-level A tail water quality of urban sewage treatment plants to surface water quality levels of Class IV to Class V, effectively preventing sewage from polluting the environment.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: The present invention provides a composite filler, which is mainly prepared from the following raw materials: in parts by mass, 20-40 parts of combined polyether, 0.005-0.02 parts of anaerobic ammonia-oxidizing bacteria, 0.005-0.02 parts of solid nitrifying bacteria, 0.005-0.02 parts of biological enzyme, 1-3 parts of iron powder, 1-7 parts of pyrite powder, 1-3 parts of carbon black, 10-20 parts of foaming agent, 30-50 parts of isocyanate, and 3-10 parts of loaded filler.

[0010] Preferably, it is mainly made of the following raw materials: by mass, 25-38 parts of combined polyether, 0.008-0.015 parts of anaerobic ammonia-oxidizing bacteria, 0.008-0.015 parts of solid nitrifying bacteria, 0.008-0.015 parts of biological enzymes, 1-2 parts of iron powder, 3-6 parts of pyrite powder, 1-2 parts of carbon black, 12-18 parts of foaming agent, 35-45 parts of isocyanate, and 5-8 parts of loaded filler.

[0011] Preferably, it is mainly made of the following raw materials: by mass, 35 parts of combined polyether, 0.01 parts of anaerobic ammonia-oxidizing bacteria, 0.01 parts of solid nitrifying bacteria, 0.01 parts of biological enzymes, 1 part of iron powder, 5 parts of pyrite powder, 1 part of carbon black, 15 parts of foaming agent, 40 parts of isocyanate, and 6 parts of loaded filler.

[0012] In the above scheme, by combining multiple components in a specific ratio, the biological treatment efficiency can be enhanced and a suitable microbial growth environment can be provided.

[0013] The combined polyether reacts with isocyanate to form a polyurethane foam with a porous structure. This porous structure provides a high surface area for the filler, significantly enhancing microbial adhesion and facilitating the biological treatment process. Furthermore, this porous structure provides space for microorganisms and enzymes to grow and function, creating a favorable physical and chemical environment for microorganisms such as anaerobic ammonium oxidizing bacteria and nitrifying bacteria. This enhances their activity and, in synergy with enzymes, further accelerates the degradation of pollutants such as ammonia nitrogen.

[0014] On the other hand, this porous structure can also improve the mass transfer efficiency of the filler, allowing pollutants in the wastewater to more fully contact the microorganisms on the filler surface, accelerating the reaction process. In addition, the combined polyether works synergistically with the foaming agent and isocyanate to adjust the physical properties of the foam, such as density, porosity, and strength, thereby optimizing the overall performance of the filler. Enhanced biological treatment efficiency: By providing a favorable physical and chemical environment, the combined polyether indirectly enhances the activity of microorganisms such as anaerobic ammonia-oxidizing bacteria and nitrifying bacteria, while also synergizing with biological enzymes to further accelerate the degradation process of pollutants (such as ammonia nitrogen).

[0015] Anaerobic ammonium oxidizing bacteria can directly convert ammonia nitrogen and nitrite nitrogen into nitrogen gas under anoxic conditions, while nitrifying bacteria are responsible for converting ammonia nitrogen into nitrite nitrogen and nitrate nitrogen. By using anaerobic ammonium oxidizing bacteria and solid nitrifying bacteria, a more complete and efficient biological denitrification system can be constructed to effectively remove nitrogen pollutants in wastewater.

[0016] Biological enzymes can act as catalysts to accelerate the metabolic process of microorganisms and improve the degradation efficiency of pollutants.

[0017] Iron and pyrite powders not only serve as electron donors, supporting the metabolic activities of specialized microorganisms like anaerobic ammonium oxidation (ANAMMOX), but their surfaces also provide attachment sites for microorganisms, enabling the formation of stable biofilms. The large surface area and porous structure of the loaded fillers provide a vast attachment surface for microorganisms, facilitating the formation of efficient biofilms and enhancing their stability and impact resistance.

[0018] Carbon black can serve as a microbial attachment point and can play a certain conductive or adsorbent role, which is helpful for electron transfer or pollutant adsorption. In addition, carbon black and iron powder can spontaneously form a microscopic iron-carbon primary cell when treating wastewater through the primary cell reaction between iron and carbon. The Fe generated in the electrolysis process 2+ , H2O2 and [H] are highly reactive and can react with most pollutants, converting easily soluble harmful substances into insoluble ones, high-valent toxic heavy metal substances into low-valent ones, and cyclic macromolecular organic matter into easily degradable small molecular substances through ring opening and chain breaking, accompanied by physical and chemical processes such as flocculation and electrochemical adsorption, thereby achieving efficient removal of harmful substances.

[0019] In summary, the present invention not only incorporates functional microorganisms and enzymes that can efficiently remove specific pollutants, but also, by adding specific inorganic materials and utilizing polyurethane foaming technology, creates a porous structure that is suitable for microbial growth, enhances mass transfer, and possesses physical adsorption capacity. This significantly improves the efficiency, stability, and applicability of wastewater treatment. The present invention integrates multiple functions, including biological treatment (bacteria, enzymes), chemical assistance (iron powder, pyrite), physical structure (loaded filler, porous structure formed by blowing agent / isocyanate), and adsorption (carbon black). Combined with an iron-carbon galvanic cell, this composite filler can simultaneously or synergistically treat multiple pollutants with greater efficiency and stability. Application of this composite filler in constructed wetlands can significantly enhance nitrogen and phosphorus removal, as well as heavy metal ion pollution removal, thereby significantly improving water quality, purifying Class A tailwater from urban sewage treatment plants to surface water quality levels of Class IV to V.

[0020] Preferably, the iron powder is any one of reduced iron powder and atomized iron powder. Both iron powders have good physical properties and can form an iron-carbon galvanic cell with carbon black to further improve the treatment effect of sewage.

[0021] Preferably, the isocyanate is any one of polymeric diphenylmethane diisocyanate, pure diphenylmethane diisocyanate, and toluene diisocyanate.

[0022] Preferably, the loaded filler is any one of activated carbon, starch, and cellulose, or a mixture of several of them.

[0023] Preferably, the loaded filler is obtained by mixing activated carbon and starch; the mass ratio of the activated carbon to the starch is (1-2):1; Preferably, the mass ratio of the activated carbon to the starch is 1.5:1.

[0024] Activated carbon, starch, and cellulose are all well-established fillers in this field. In a further embodiment of the present invention, a mixture of activated carbon and starch is selected. Activated carbon, with its high specific surface area and porous structure, provides numerous physical adsorption sites, effectively adsorbing organic pollutants, heavy metal ions, and other substances from water. Furthermore, the oxygen-containing functional groups (such as hydroxyl and carboxyl groups) on the surface of activated carbon can chemically adsorb pollutants, further enhancing its purification capacity. Starch has excellent biocompatibility and biodegradability, and its polar groups are capable of adsorbing polar pollutants. When the two are combined, the high specific surface area and porous structure of the activated carbon provide more adsorption space for the starch, while the polar groups of the starch can adsorb polar pollutants that are difficult for activated carbon to adsorb. The synergistic effect of the two significantly enhances adsorption capacity. In a further embodiment, a ratio of 1.5:1 is selected. This ratio maximizes the synergistic effect while avoiding the loss of adsorption capacity caused by an imbalance in the ratio, ensuring that both the physical adsorption capacity of the activated carbon and the polar adsorption capacity of the starch are fully utilized. On the other hand, the flexibility of starch enhances the filler's mechanical strength, preventing the structural fragility that can occur when activated carbon is used alone. At a 1.5:1 ratio, the filler maintains sufficient strength without compromising overall performance due to a high starch content. Furthermore, activated carbon and starch are both relatively low-cost and widely available, making a 1.5:1 ratio a good balance of performance, cost-effectiveness, and environmental friendliness, making it suitable for large-scale applications.

[0025] The present invention also provides a method for preparing the composite filler, comprising the following steps: The composite polyether, anaerobic ammonia-oxidizing bacteria, solid nitrifying bacteria, biological enzyme, iron powder, pyrite powder, carbon black, foaming agent, isocyanate and loaded filler are mixed and foamed to obtain the product.

[0026] The preparation method is simple and convenient, and can produce composite fillers quickly and efficiently.

[0027] The present invention also provides a method for preparing the composite filler, comprising the following steps: The composite polyether, iron powder, pyrite powder, carbon black, isocyanate and a foaming agent are mixed and foamed to obtain a rigid polyurethane foam; The anaerobic ammonium oxidizing bacteria, solid nitrifying bacteria, biological enzymes and loaded fillers are uniformly mixed to obtain a mixture; The rigid polyurethane foam is mixed with the mixture to obtain the product.

[0028] The above-mentioned preparation method is a distributed operation method. After foaming to obtain rigid polyurethane foam, the mixture obtained by mixing anaerobic ammonia oxidizing bacteria, solid nitrifying bacteria, biological enzymes and loaded fillers is combined with the mixture. On the one hand, this method can avoid damage to anaerobic ammonia oxidizing bacteria, solid nitrifying bacteria and biological enzymes during the foaming process; on the other hand, this method pre-mixes anaerobic ammonia oxidizing bacteria, solid nitrifying bacteria, biological enzymes with loaded fillers, which can provide a relatively stable and protective microenvironment, thereby further protecting the active ingredients of microorganisms; and this method can make anaerobic ammonia oxidizing bacteria, solid nitrifying bacteria, biological enzymes and loaded fillers form a relatively stable granular or powdered mixture, which is then mixed with foam to ensure that the microorganisms are present in the final product in a more stable form and are not easily lost; on the other hand, this method can ensure that anaerobic ammonia oxidizing bacteria, solid nitrifying bacteria and biological enzymes are more evenly and effectively attached to the pore walls of the foam. In short, the method is simple to operate and can protect biological activity while ensuring the efficiency of filler preparation, thereby further ensuring that the prepared composite filler has a good sewage treatment effect.

[0029] The present invention also provides an artificial wetland restoration filler layer, comprising: a first crushed stone layer, a ceramsite layer, a synergistic filler layer, a second crushed stone layer, a coarse sand layer and a soil layer arranged in sequence from bottom to top, wherein the synergistic filler layer is the above-mentioned composite filler.

[0030] The artificial wetland restoration filler layer has good sewage treatment capabilities and can effectively remove nitrogen, phosphorus and heavy metal ions in sewage. When applied to sewage treatment processes in scenarios such as urban sewage treatment plants, it can purify the Class A tail water quality of urban sewage treatment plants to surface water quality levels of Class IV to Class V, effectively preventing sewage from polluting the environment.

[0031] Compared with the prior art, the present invention has the following beneficial effects: This invention not only incorporates functional microorganisms and enzymes that can efficiently remove specific pollutants, but also, by adding specific inorganic materials and utilizing polyurethane foaming technology, creates a porous structure that is suitable for microbial growth, enhances mass transfer, and possesses physical adsorption capacity. This significantly improves the efficiency, stability, and applicability of wastewater treatment. This invention integrates multiple functions, including biological treatment (bacteria, enzymes), chemical assistance (iron powder, pyrite), physical structure (loaded filler, porous structure formed by blowing agent / isocyanate), and adsorption (carbon black). Combined with an iron-carbon galvanic cell, this composite filler can simultaneously or synergistically treat multiple pollutants with greater efficiency and stability. When applied to constructed wetlands, this composite filler can significantly enhance nitrogen and phosphorus removal, as well as heavy metal ion pollution removal, thereby significantly improving water quality, purifying Class A tailwater from urban sewage treatment plants to surface water quality levels of Class IV to V. DETAILED DESCRIPTION

[0032] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0033] Example 1 Weigh and combine 35 g of polyether, 0.01 g of anaerobic ammonia-oxidizing bacteria, 0.01 g of solid nitrifying bacteria, 0.01 g of biological enzyme, 1 g of iron powder, 5 g of pyrite powder, 1 g of carbon black, 15 g of foaming agent, 40 g of isocyanate, and 6 g of loaded filler.

[0034] The polyether composition, anaerobic ammonia-oxidizing bacteria, solid nitrifying bacteria, biological enzymes, iron powder, pyrite powder, carbon black, foaming agent, isocyanate, and loaded filler are thoroughly mixed and then foamed to obtain the product. The obtained product can be cut into blocks of different sizes, such as 5-10 cm, for easy use.

[0035] In this embodiment, the iron powder is reduced iron powder, the foaming agent is water, the isocyanate is polymeric diphenylmethane diisocyanate (ie, polymeric MDI), and the loaded filler is a mixture of activated carbon and starch, with a mass ratio of activated carbon to starch of 1.5:1.

[0036] Anaerobic ammonia-oxidizing bacteria were purchased from Delan Water Technology Co., Ltd., with an effective viable count of 10 billion CFU / g and a contaminant bacterial rate of 0.23%. Solid nitrifying bacteria were purchased from Pro Biotechnology (Shanghai) Co., Ltd. in a powder form, with an effective viable count of 20 billion CFU / g and a contaminant bacterial rate of 0.19%. Enzymes were purchased from New Yangshao Biological Co., Ltd. in a yellow powder form, with a viable count of 20 billion CFU / g of Bacillus velezensis and a contaminant bacterial rate of 0.19%.

[0037] After testing, the physical and chemical parameters of the composite filler are: density 0.33g / cm 3 , bulk density 0.25g / cm 3 , porosity 39.1%, crushing rate 0.09%, specific surface area 868m 2 / g, denitrification efficiency 11.5g / m 3 .d, phosphorus removal efficiency 0.7g / m 3 .d, heavy metal Cr 6+ Removal rate: 96.3%.

[0038] Example 2 Weigh and combine 35 g of polyether, 0.01 g of anaerobic ammonia-oxidizing bacteria, 0.01 g of solid nitrifying bacteria, 0.01 g of biological enzyme, 1 g of iron powder, 5 g of pyrite powder, 1 g of carbon black, 15 g of foaming agent, 40 g of isocyanate, and 6 g of loaded filler.

[0039] The combined polyether, iron powder, pyrite powder, carbon black, isocyanate, and a foaming agent are mixed and foamed to obtain a rigid polyurethane foam. Anaerobic ammonia oxidizing bacteria, solid nitrifying bacteria, biological enzymes, and loaded fillers are uniformly mixed to obtain a mixture.

[0040] The rigid polyurethane foam is cut into blocks of different sizes such as 5-10 cm, and the cut rigid polyurethane foam is mixed with the mixture to obtain the composite filler.

[0041] In this embodiment, the iron powder is reduced iron powder, the foaming agent is water, the isocyanate is polymeric diphenylmethane diisocyanate (ie, polymeric MDI), and the loaded filler is a mixture of activated carbon and starch, with a mass ratio of activated carbon to starch of 1.5:1.

[0042] Anaerobic ammonia-oxidizing bacteria were purchased from Delan Water Technology Co., Ltd., with an effective viable count of 10 billion CFU / g and a contaminant bacterial rate of 0.23%. Solid nitrifying bacteria were purchased from Pro Biotechnology (Shanghai) Co., Ltd. in a powder form, with an effective viable count of 20 billion CFU / g and a contaminant bacterial rate of 0.19%. Enzymes were purchased from New Yangshao Biological Co., Ltd. in a yellow powder form, with a viable count of 20 billion CFU / g of Bacillus velezensis and a contaminant bacterial rate of 0.19%.

[0043] After testing, the physical and chemical parameters of the composite filler are: density 0.31g / cm 3 , bulk density 0.27g / cm 3 , porosity 38.9%, crushing rate 0.07%, specific surface area 870m 2 / g, denitrification efficiency 13.6g / m 3 .d, phosphorus removal efficiency 0.9g / m 3 .d, heavy metal Cr 6+ Removal rate: 98.6%.

[0044] Example 3 The only difference between this example and Example 2 is that: in this example, 38g of polyether, 0.015g of anaerobic ammonia-oxidizing bacteria, 0.015g of solid nitrifying bacteria, 0.015g of biological enzyme, 2g of iron powder, 6g of pyrite powder, 2g of carbon black, 18g of foaming agent, 45g of isocyanate, and 8g of loaded filler are combined. The isocyanate is pure diphenylmethane diisocyanate (i.e., pure MDI), and the foaming agent is dichloromethane.

[0045] After testing, the physical and chemical parameters of the composite filler are: density 0.30g / cm3 , bulk density 0.28g / cm 3 , porosity 38.1%, crushing rate 0.08%, specific surface area 867m 2 / g, denitrification efficiency 12.5g / m 3 .d, phosphorus removal efficiency 0.7g / m 3 .d, heavy metal Cr 6+ Removal rate: 97.5%.

[0046] Example 4 The only difference between this example and Example 2 is that: in this example, 25 g of polyether, 0.008 g of anaerobic ammonia-oxidizing bacteria, 0.008 g of solid nitrifying bacteria, 0.008 g of biological enzyme, 1 g of iron powder, 3 g of pyrite powder, 1 g of carbon black, 12 g of foaming agent, 35 g of isocyanate, and 5 g of loaded filler are combined. The iron powder is atomized iron powder.

[0047] After testing, the physical and chemical parameters of the composite filler are: density 0.31g / cm 3 , bulk density 0.29g / cm 3 , porosity 38.5%, crushing rate 0.09%, specific surface area 863m 2 / g, denitrification efficiency 12.8g / m 3 .d, phosphorus removal efficiency 0.7g / m 3 .d, heavy metal Cr 6+ Removal rate: 97.6%.

[0048] Example 5 The only difference between this embodiment and embodiment 2 is that: in this embodiment, 20g of polyether, 0.005g of anaerobic ammonia-oxidizing bacteria, 0.005g of solid nitrifying bacteria, 0.005g of biological enzyme, 1g of iron powder, 1g of pyrite powder, 1g of carbon black, 10g of foaming agent, 30g of isocyanate, and 3g of loaded filler are combined.

[0049] After testing, the physical and chemical parameters of the composite filler are: density 0.32g / cm 3 , bulk density 0.30g / cm 3 , porosity 38.8%, crushing rate 0.09%, specific surface area 868m 2 / g, denitrification efficiency 13.0g / m 3 .d, phosphorus removal efficiency 0.9g / m 3 .d, heavy metal Cr 6+ Removal rate 98.0%.

[0050] Example 6 The only difference between this example and Example 2 is that: in this example, 40 g of polyether, 0.02 g of anaerobic ammonia-oxidizing bacteria, 0.02 g of solid nitrifying bacteria, 0.02 g of biological enzyme, 3 g of iron powder, 7 g of pyrite powder, 3 g of carbon black, 20 g of foaming agent, 50 g of isocyanate, and 10 g of loaded filler are combined. The isocyanate is toluene diisocyanate (TDI).

[0051] After testing, the physical and chemical parameters of the composite filler are: density 0.30g / cm 3 , bulk density 0.28g / cm 3 , porosity 39.0%, crushing rate 0.07%, specific surface area 870m 2 / g, denitrification efficiency 13.2g / m 3 .d, phosphorus removal efficiency 0.8g / m 3 .d, heavy metal Cr 6+ Removal rate: 98.3%.

[0052] Example 7 The only difference between this embodiment and embodiment 2 is that in this embodiment, the mass ratio of activated carbon to starch in the loaded filler is 1:1.

[0053] After testing, the physical and chemical parameters of the composite filler are: density 0.32g / cm 3 , bulk density 0.28g / cm 3 , porosity 39.0%, crushing rate 0.09%, specific surface area 872m 2 / g, denitrification efficiency 13.4g / m 3 .d, phosphorus removal efficiency 0.8g / m 3 .d, heavy metal Cr 6+ Removal rate: 98.2%.

[0054] Example 8 The only difference between this embodiment and embodiment 2 is that in this embodiment, the mass ratio of activated carbon to starch in the loaded filler is 2:1.

[0055] After testing, the physical and chemical parameters of the composite filler are: density 0.31g / cm 3 , bulk density 0.29g / cm 3 , porosity 39.1%, crushing rate 0.08%, specific surface area 868m 2 / g, denitrification efficiency 13.3g / m 3 .d, phosphorus removal efficiency 0.8g / m 3 .d, heavy metal Cr 6+ Removal rate: 98.4%.

[0056] Example 9 The only difference between this embodiment and embodiment 2 is that in this embodiment, the loaded filler is activated carbon.

[0057] After testing, the physical and chemical parameters of the composite filler are: density 0.32g / cm 3 , bulk density 0.31g / cm 3 , porosity 38.8%, crushing rate 0.08%, specific surface area 865m 2 / g, denitrification efficiency 12.7g / m 3 .d, phosphorus removal efficiency 0.6g / m 3 .d, heavy metal Cr 6+ Removal rate: 97.7%.

[0058] Example 10 The only difference between this embodiment and embodiment 2 is that in this embodiment, the loaded filler is starch.

[0059] After testing, the physical and chemical parameters of the composite filler are: density 0.31g / cm 3 , bulk density 0.30g / cm 3 , porosity 38.9%, crushing rate 0.08%, specific surface area 865m 2 / g, denitrification efficiency 10.7g / m 3 .d, phosphorus removal efficiency 0.6g / m 3 .d, heavy metal Cr 6+ Removal rate: 96.3%.

[0060] Example 11 The only difference between this embodiment and embodiment 2 is that in this embodiment, the loaded filler is cellulose.

[0061] After testing, the physical and chemical parameters of the composite filler are: density 0.28g / cm 3 , bulk density 0.23g / cm 3 , porosity 38.5%, crushing rate 0.05%, specific surface area 872m 2 / g, denitrification efficiency 10.1g / m 3 .d, phosphorus removal efficiency 0.7g / m 3 .d, heavy metal Cr 6+ Removal rate: 96.5%.

[0062] Example 12 The only difference between this embodiment and embodiment 2 is that in this embodiment, the loaded filler is a mixture of activated carbon and cellulose, and the mass ratio of activated carbon to cellulose is 1.5:1.

[0063] After testing, the physical and chemical parameters of the composite filler are: density 0.25g / cm 3 , bulk density 0.26g / cm 3, porosity 38.3%, crushing rate 0.07%, specific surface area 865m 2 / g, denitrification efficiency 12.8g / m 3 .d, phosphorus removal efficiency 0.7g / m 3 .d, heavy metal Cr 6+ Removal rate: 97.3%.

[0064] Example 13 The present embodiment provides a filler layer for artificial wetland restoration, comprising: a first crushed stone layer, a ceramsite layer, a synergistic filler layer, a second crushed stone layer, a coarse sand layer and a soil layer, which are arranged in sequence from bottom to top, wherein the synergistic filler layer adopts the composite filler prepared in Example 2. The thickness of the first crushed stone layer is 40±5cm, and the average particle size of the crushed stone is 20mm. The thickness of the biological ceramsite layer is 10±2.5cm, and the average particle size of the ceramsite is 15mm. The thickness of the synergistic filler layer is 50cm±5cm, and the average particle size of the filler is 5cm. The thickness of the second crushed stone layer is 30±5cm, and the average particle size of the crushed stone is 10mm. The thickness of the coarse sand layer is 30±5cm, and the average particle size of the coarse sand is 1mm. The thickness of the soil layer is 30±5cm, and sandy soil is selected.

[0065] The artificial wetland repair filler layer of this embodiment was used in combination with the planting of emergent water plants reed and aquatic plants Siberian iris to conduct a treatment test on the first-level A tail water of the urban sewage treatment plant (cycle 3 months). The test found that: the BOD5 pollution load was reduced by 2g / (m 2 .d), COD Cr Pollution reduction load reaches 6g / (m 2 .d), reducing NH3-N pollution by 2.8g / (m 2 .d), TN pollution reduction load reaches 3.55g / (m 2 .d), TP pollution reduction load reaches 0.5g / (m 2 .d) The heavy metal ions of chromium, cadmium, copper and mercury are all below the detection limit, so that the first-class A tail water quality of the urban sewage treatment plant is purified to the surface water quality level of Class IV.

[0066] The following conclusions can be drawn based on the above example data: From the data of Examples 1-12, it can be found that the density of the composite fillers prepared by the solution of the present invention does not exceed 0.5 g / cm 3 , the bulk density does not exceed 0.5g / cm 3 The porosity is greater than 35%, the crushing rate is less than 0.1%, and the specific surface area is more than 600m 2 / g, and the denitrification efficiency exceeds 10g / m 3 .d, the phosphorus removal efficiency exceeds 0.5g / m 3 .d, heavy metal Cr6+ The removal rates are all over 95%. Therefore, the composite filler of the present invention can meet the standard requirements. Among them, the composite filler of Example 2 has the best overall physical and chemical properties, and its denitrification efficiency reaches 13.6g / m 3 .d, the phosphorus removal efficiency reached 0.9g / m 3 .d, heavy metal Cr 6+ The removal rate reached 98.6%.

[0067] Comparing Example 1 and Example 2, it can be seen that the denitrification and phosphorus removal efficiency of Example 2 and the heavy metal Cr 6+ The removal rates are significantly better than those in Example 1. This may be because in Example 2, after the rigid polyurethane foam is foamed, a mixture obtained by mixing anaerobic ammonia-oxidizing bacteria, solid nitrifying bacteria, biological enzymes and loaded fillers is combined with the rigid polyurethane foam through a distribution operation, which effectively improves the activity and stability of the anaerobic ammonia-oxidizing bacteria, solid nitrifying bacteria and biological enzymes, thereby improving their physical and chemical properties.

[0068] Comparing Example 2 with Examples 7 and 8, it can be seen that the denitrification and phosphorus removal efficiency of Example 2 and the heavy metal Cr 6+ The removal rates were better than those in Examples 7 and 8. Therefore, when the mass ratio of activated carbon to starch was 1.5:1, the best removal of nitrogen, phosphorus and heavy metal Cr could be achieved. 6+ Remove effect.

[0069] Comparing Example 2 with Examples 9-12, it can be seen that the denitrification and phosphorus removal efficiency of Example 2 and the heavy metal Cr 6+ The removal rates are better than those of Examples 9-12, which shows that compared with a single loaded filler, the combination of two loaded fillers can better improve the physical and chemical properties of the final composite filler. And compared with other combinations, the combination of activated carbon and starch can achieve the best removal of nitrogen, phosphorus and heavy metal Cr. 6+ Remove effect.

[0070] In summary, the composite filler according to the embodiment of the present invention has better denitrification, dephosphorization and heavy metal removal capabilities, and its application in artificial wetlands can significantly improve water quality.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite filler, characterized in that: The invention is mainly prepared from the following raw materials: by weight, 20-40 parts of combined polyether, 0.005-0.02 parts of anaerobic ammonia-oxidizing bacteria, 0.005-0.02 parts of solid nitrifying bacteria, 0.005-0.02 parts of biological enzyme, 1-3 parts of iron powder, 1-7 parts of pyrite powder, 1-3 parts of carbon black, 10-20 parts of foaming agent, 30-50 parts of isocyanate and 3-10 parts of loaded filler.

2. The composite filler according to claim 1, characterized in that The invention is mainly prepared from the following raw materials: by weight, 25-38 parts of combined polyether, 0.008-0.015 parts of anaerobic ammonia-oxidizing bacteria, 0.008-0.015 parts of solid nitrifying bacteria, 0.008-0.015 parts of biological enzyme, 1-2 parts of iron powder, 3-6 parts of pyrite powder, 1-2 parts of carbon black, 12-18 parts of foaming agent, 35-45 parts of isocyanate and 5-8 parts of loaded filler.

3. The composite filler according to claim 1, characterized in that It is mainly made of the following raw materials: by mass, 35 parts of combined polyether, 0.01 parts of anaerobic ammonia-oxidizing bacteria, 0.01 parts of solid nitrifying bacteria, 0.01 parts of biological enzymes, 1 part of iron powder, 5 parts of pyrite powder, 1 part of carbon black, 15 parts of foaming agent, 40 parts of isocyanate, and 6 parts of loaded filler.

4. The composite filler according to any one of claims 1 to 3, characterized in that: The iron powder is any one of reduced iron powder and atomized iron powder.

5. The composite filler according to any one of claims 1 to 3, characterized in that: The isocyanate is any one of polymeric diphenylmethane diisocyanate, pure diphenylmethane diisocyanate, and toluene diisocyanate.

6. The composite filler according to any one of claims 1 to 3, characterized in that: The loaded filler is any one of activated carbon, starch, and cellulose, or a mixture of several of them.

7. The composite filler according to claim 6, characterized in that The loaded filler is obtained by mixing activated carbon and starch; the mass ratio of the activated carbon to the starch is (1-2):1; Preferably, the mass ratio of the activated carbon to the starch is 1.5:

1.

8. A method for preparing a composite filler according to any one of claims 1 to 7, characterized in that: The following steps are involved: The composite polyether, anaerobic ammonia-oxidizing bacteria, solid nitrifying bacteria, biological enzyme, iron powder, pyrite powder, carbon black, foaming agent, isocyanate and loaded filler are mixed and foamed to obtain the product.

9. A method for preparing a composite filler according to any one of claims 1 to 7, characterized in that: The following steps are involved: The composite polyether, iron powder, pyrite powder, carbon black, isocyanate and a foaming agent are mixed and foamed to obtain a rigid polyurethane foam; The anaerobic ammonium oxidizing bacteria, solid nitrifying bacteria, biological enzymes and loaded fillers are uniformly mixed to obtain a mixture; The rigid polyurethane foam is mixed with the mixture to obtain the product.

10. A filler layer for repairing artificial wetlands, characterized in that: include: A first crushed stone layer, a ceramsite layer, a synergistic filler layer, a second crushed stone layer, a coarse sand layer and a soil layer are sequentially arranged from bottom to top, wherein the synergistic filler layer is the composite filler according to any one of claims 1 to 7.