A functional material for wastewater treatment prepared based on natural blue iron ore and natural limonite and its application in simultaneous denitrification and phosphorus recovery

Abstract

A wastewater treatment functional material prepared based on natural violet iron ore and natural limonite, and its application in simultaneous denitrification and phosphorus recovery, relates to the technical field of deep denitrification and phosphorus recovery in wastewater treatment. A 3D iron-sulfur-phosphorus porous functional material or a 3D hematite-composite phosphorus functional material is prepared using 3D printing technology using natural violet iron ore, natural limonite, a binder, a porogen, or sulfur. The nano-zero-valent iron phosphorus and sulfur components within the 3D iron-sulfur-phosphorus porous functional material can serve as electron donors and electron transfer media for denitrifying Thiobacillus during autotrophic denitrification, reducing nitrate and nitrite, or as an electron shuttle for protease synthesis, thereby enhancing the denitrification biological activity of Denitrifying Thiobacillus. Alternatively, the 3D hematite-composite phosphorus functional material can serve as an electron acceptor for iron-anaerobic ammonium-oxidizing bacteria during iron-anaerobic ammonium oxidation, promoting electron transfer and enzyme synthesis in the microorganisms, improving wastewater denitrification performance, and achieving ammonia nitrogen oxidation and phosphorus recovery.

Description

Technical Field

[0001] The present invention relates to the technical field of deep denitrification and phosphorus recovery in sewage treatment, and in particular to a functional material for wastewater treatment prepared based on natural blue iron ore and natural limonite, and its application in simultaneous denitrification and phosphorus recovery. Background Art

[0002] Phosphorus and nitrogen are the primary factors contributing to eutrophication in lakes and oceans. In recent years, the control of ammonia nitrogen and phosphorus has been a primary focus in surface water environmental management and water treatment. With the increasing severity of eutrophication in lakes and oceans, particularly the widespread appearance of black and smelly rivers in cities, total phosphorus, total nitrogen, and nitrate nitrogen have exceeded discharge standards. Consequently, these levels have been included as key indicators for water pollution control and wastewater discharge. Stringent discharge standards for total nitrogen and total phosphorus have been established across the country in recent years.

[0003] Heterotrophic denitrification-nitrification has always been the main process technology for wastewater denitrification. It uses an aerobic process to convert ammonia nitrogen and organic nitrogen in the water into nitrate nitrogen through biochemical reactions. The nitrate-nitrogen-containing water is then placed in an anoxic tank and denitrified using organic matter or reducing agents to reduce the nitrate nitrogen to nitrogen gas. Currently, heterotrophic denitrification denitrification technology also has some problems: First, the high reflow ratio causes the total nitrogen to meet the emission standards, making the wastewater treatment plant uneconomical and energy-intensive. Second, because the wastewater stays in the drainage pipes and septic tanks for too long, the carbon source is insufficient and the carbon-nitrogen ratio is too low, which cannot meet the organic carbon demand of heterotrophic denitrification. Third, when the carbon source is insufficient, adding sodium acetate to supplement the carbon source will result in excessively high denitrification costs, resulting in excessively high effluent COD and secondary pollution.

[0004] To address the shortcomings of heterotrophic denitrification and meet the needs of deep denitrification in water treatment, autotrophic denitrification, a representative technology, has rapidly developed in recent years. Sulfur autotrophic denitrification is a process in which facultative anaerobic microorganisms such as Thiobacillus denitrificans utilize inorganic carbon as a carbon source to complete anabolism, while simultaneously reducing nitrate to nitrogen gas using sulfur and reduced sulfur compounds (sulfide, sulfite, and thiosulfate) as electron donors. Denitrification using sulfur as an electron donor is the mainstream development direction.

[0005] At present, solid sulfur autotrophic denitrification materials still have the problem of slow denitrification rate. Sulfur autotrophic denitrification materials are all insoluble solid substances. They interact with microorganisms and require the addition of complex electron shuttles during the microbial metabolism process. This is a key factor restricting the denitrification reaction speed and the fundamental reason for the slow sulfur autotrophic denitrification rate. Usually, heterotrophic denitrification anaerobic biological deep filters with sodium acetate are added, but there is a problem of too long hydraulic retention time. The hydraulic retention time of natural iron sulfide autotrophic denitrification is mostly required to be more than 4h, which leads to excessive investment in the construction of sulfur autotrophic denitrification treatment pools and poor economic efficiency. How to improve the biological reaction rate of sulfur autotrophic denitrification and phosphorus recovery materials through improvements in material preparation methods is a key technical problem that urgently needs to be solved. In addition, the current sulfur autotrophic denitrification and phosphorus recovery materials have problems such as low bioload of autotrophic microorganisms, low open porosity, and low efficiency of phosphorus recovery.

[0006] In recent years, Feammox has attracted extensive attention from scholars as a new biological denitrification technology. Feammox is a new green and environmentally friendly autotrophic biological denitrification technology mediated by iron. The Feammox reaction is driven by microorganisms in an anaerobic environment to convert NH4 + and Fe(Ⅲ) act as electron donor and electron acceptor respectively. Fe(Ⅲ) is reduced to Fe(Ⅱ), while NH4 + It is converted into several different forms of nitrogen, such as nitrite, nitrate and nitrogen gas. During the wastewater treatment process, the iron ammonia oxidation reaction occurs in anoxic and autotrophic processes, which can reduce the costs associated with aeration, external carbon source addition and sludge treatment. It is a green and environmentally friendly water treatment process. Iron ammonia oxidation has a wider pH application range. Compared with anaerobic ammonia oxidation, iron-reducing bacteria also have stronger survival ability than anaerobic ammonia oxidizing bacteria. However, there are currently problems with trivalent iron-containing fillers due to their low porosity, low biological activity, low bioload, and low phosphorus recovery efficiency, which affect their removal effect.

[0007] Natural limonite is a widely distributed iron oxide mineral that exists in swamp environments and is formed by anaerobic reduction of microorganisms. In addition to goethite, limonite ore is often accompanied by other iron-containing minerals, clay minerals, and organic matter. Natural limonite is roasted to obtain iron oxide for ironmaking. Low-grade limonite is usually not utilized and is often discarded as waste rock during ore mining, which not only damages the environment but also occupies land. Natural limonite is a hydrated iron-containing phosphate mineral found in geological environments, containing a small amount of Mg. 2+ 、Mn 2+ and Ca 2+ Can replace Fe in the structure 2+Meanwhile, natural violetite is a secondary mineral that can be found in many geological environments: in oxidation zones of metal deposits, in granite pegmatites containing phosphate minerals, in glauconite sediments and clays, as well as in recent alluvial deposits that replaced organic materials such as lignite, peat, forest soils and bog ironstones.

[0008] In order to realize the resource utilization of natural blue iron ore and natural limonite, the present invention uses them to prepare 3D iron-sulfur-phosphorus porous functional materials and 3D hematite composite phosphorus functional materials, and applies them to the simultaneous denitrification and phosphorus recovery in wastewater treatment, which can greatly reduce the cost of wastewater treatment. Summary of the Invention

[0009] To address the above-mentioned technical problems, the present invention proposes a wastewater treatment functional material prepared from natural violet iron and natural limonite, a preparation method, and its application in simultaneous denitrification and phosphorus recovery. A 3D iron-sulfur-phosphorus porous functional material or a 3D hematite-composite phosphorus functional material is prepared using 3D printing technology using natural violet iron, natural limonite, a binder, a porogen, or sulfur. The nano-zero-valent iron phosphorus, nano-zero-valent iron, and sulfur components within the 3D iron-sulfur-phosphorus porous functional material can serve as electron donors and electron transfer media for denitrifying Thiobacillus during autotrophic denitrification, reducing nitrate and nitrite. Alternatively, they can serve as electron shuttles for protease synthesis, thereby enhancing the denitrification biological activity of denitrifying Thiobacillus. The 3D hematite-composite phosphorus functional material can serve as an electron acceptor for iron-anaerobic ammonia-oxidizing bacteria, promoting electron transfer and enzyme synthesis in the microorganisms, improving wastewater denitrification performance and achieving simultaneous ammonia nitrogen oxidation and phosphorus recovery.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] First, the present invention proposes a functional material for wastewater treatment prepared based on natural violet iron ore and natural limonite, which is made of 80-95% natural violet iron ore and natural limonite, 4-14% binder, 0.1-10% porogen and 0-10% sulfur, wherein the mass ratio of natural violet iron ore to natural limonite is 1-5:1.

[0012] As a preferred technical solution of the present invention, the porogen used to prepare the wastewater treatment functional material is selected from straw debris, leaf debris, pulp fiber or sawdust, and the binder used is selected from water glass, attapulgite clay, sepiolite clay, bentonite, montmorillonite or kaolin.

[0013] Secondly, the present invention proposes a preparation method for a wastewater treatment functional material, namely a 3D iron-sulfur-phosphorus porous functional material, which is made of 80-95% natural violet iron ore and natural limonite, 4-14% binder, 0.1-10% porogen and 0.1-10% sulfur. First, the natural violet iron ore, natural limonite, porogen, binder and sulfur are crushed to obtain a powder with a particle size of 0.0075 mm. Then, the natural violet iron ore powder and the natural limonite powder are respectively calcined at 400-1000°C under a hydrogen atmosphere for 1-4 hours to obtain a nano zero-valent iron-phosphorus composite material and a nano zero-valent iron composite material, respectively; then, the nano zero-valent iron-phosphorus composite material, the nano zero-valent iron composite material, the binder powder, the porogen powder and the sulfur powder are uniformly mixed according to mass percentage. Finally, the mixture is weighed and printed using 3D printing technology to prepare a 3D iron-sulfur-phosphorus porous functional material with a particle size of 1-20 mm.

[0014] The 3D iron-sulfur-phosphorus porous functional material is added to wastewater that requires deep denitrification and phosphorus recovery. It acts as an electron donor in autotrophic denitrification, reducing nitrate nitrogen to nitrogen gas to achieve denitrification. At the same time, ferrous ions combine with phosphorus in the water under the induction of phosphorus-containing crystal seeds to achieve phosphate mineralization and recovery in the form of blue iron ore. In this treatment method, the 3D iron-sulfur-phosphorus porous functional material serves as both a microbial carrier and a microbial electron donor, a microbial electron shuttle, and a crystal seed for recovering phosphorus. It can be applied to deep denitrification and phosphorus recovery of polluted water. The specific treatment plan can be as follows:

[0015] In the process section of the urban sewage treatment plant, a biological filter for denitrification and phosphorus recovery is built, and 3D iron-sulfur-phosphorus porous functional materials are added to the biological filter as electron donors and carriers for denitrification microorganisms. Before the biological filter is started, the 3D iron-sulfur-phosphorus porous functional materials are loaded into the biological filter with wastewater to be denitrified and phosphorus recovered (such as wastewater containing nitrate and phosphorus or effluent from the secondary sedimentation tank of a municipal sewage treatment plant) to form denitrifying thiobacillus biofilms.

[0016] Before starting operation, the main steps for cultivating denitrifying Thiobacillus biofilm in the autotrophic denitrification biofilter of 3D iron, sulfur and phosphorus porous functional materials are as follows:

[0017] (A) A 3D iron-sulfur-phosphorus porous functional material is loaded into a biofilter that needs to remove nitrogen and recover phosphorus, so that the sulfur content of the 3D iron-sulfur-phosphorus porous functional material in the biofilter is 50-1000 mg / L.

[0018] (B) Sludge containing denitrifying Thiobacillus or a culture medium of denitrifying Thiobacillus is added to the biofilter, accounting for 0.1-10% of the biofilter volume. A high-power peristaltic pump is used to pump the water (containing a large amount of denitrifying Thiobacillus) flowing out of the denitrification and phosphorus recovery filter outlet back to the water inlet. The water is circulated in and out for a hydraulic retention time of 1-10 hours. After a period of microbial acclimation, the denitrifying Thiobacillus will grow and multiply, attaching to the surface and internal pores of the 3D iron-sulfur-phosphorus porous functional material to form biofilms, thereby loading the 3D iron-sulfur-phosphorus porous functional material with a large amount of denitrifying Thiobacillus.

[0019] (C) During the start-up process of Thiobacillus denitrificans biofilm formation, the total nitrogen (TN), total phosphorus (TP), and COD concentrations in the inlet and outlet water were monitored. Sodium nitrate, potassium dihydrogen phosphate, and glucose were added to adjust the inlet TN concentration to 5-50 mg / L, the phosphorus concentration to 5-50 mg / L, and the COD concentration to 1-10 mg / L. The inlet and outlet water were circulated, and the Thiobacillus denitrificans biofilms matured after 5-10 days of cultivation. Alternatively, the biofilms matured when the effluent TN concentration, phosphorus concentration, and COD concentration were less than 1 mg / L, less than 1 mg / L, and less than 1 mg / L. The hydraulic retention time was adjusted between 0.5 and 2 hours to gradually bring the outlet TN, TP, and COD concentrations to Class II surface water quality standards, achieving simultaneous denitrification and phosphorus recovery.

[0020] The preparation and application of the 3D iron-sulfur-phosphorus porous functional material proposed in the present invention have the following beneficial effects:

[0021] (1) During the anaerobic denitrification and phosphorus recovery process, the 3D iron-sulfur-phosphorus porous functional material prepared by the present invention, whose main chemical components are: nano-zero-valent iron-phosphorus, sulfur, and nano-zero-valent iron, is first metabolized by microorganisms and becomes a carbon source for heterotrophic denitrification, thereby promoting microbial denitrification. Its main advantage is that the synergistic effect of nano-zero-valent iron and sulfur enhances the denitrification function of autotrophic microorganisms. Nano-zero-valent iron and sulfur can serve as electron donors and electron transfer media in the process of nitrate and nitrite reduction by denitrifying Thiobacillus, or enhance the synthesis of proteases that serve as electron shuttles, thereby improving the denitrification biological activity of denitrifying Thiobacillus, shortening the hydraulic retention time of the denitrification and phosphorus recovery filter to reach or be less than the hydraulic retention time of heterotrophic microbial denitrification.

[0022] (2) The 3D iron-sulfur-phosphorus porous functional material prepared by the present invention is lightweight and porous. It can be directly used as a carrier for autotrophic microorganisms, overcoming the problem that the use of sulfur-containing nano-mineral materials such as powdered sulfur, sulfur paste, natural pyrite, natural pyrrhotite, nanostructured pyrrhotite, etc., easily causes reactor blockage. It can also overcome the shortcomings of using sulfur-containing nano-mineral materials such as natural pyrite, natural pyrrhotite, sulfur paste, nanostructured pyrrhotite, sulfur particles, etc., such as smooth surface and low microbial loading. The 3D iron-sulfur-phosphorus porous functional material of the present invention has a large specific surface area and an open porous structure, which can accelerate the dissolution rate of sulfur and improve the activity of denitrifying thiobacillus, overcoming the problems of low mass transfer rate and slow dissolution rate of sulfur using other sulfur-containing nano-minerals. In addition, the raw material used in the present invention is a natural nano-mineral material, which is cheap, environmentally friendly, low-cost and low-energy. At the same time, the cost of the 3D iron-sulfur-phosphorus porous functional material is greatly reduced compared with heterotrophic denitrification using sodium acetate as a carbon source.

[0023] (3) The 3D iron-sulfur-phosphorus porous functional material of the present invention has a porous structure and a morphology similar to coral. It has affinity for microorganisms, is easy for the growth, reproduction and metabolism of autotrophic microorganisms, is easy for microorganisms to form flocculent extracellular organic matter, and is easily adsorbed and fixed by the extracellular membrane of microorganisms. Compared with the use of sulfur, sulfur paste, natural pyrrhotite, nanostructured pyrrhotite, and natural pyrite, the use of 3D iron-sulfur-phosphorus porous functional material can effectively improve the rate of denitrification and phosphorus recovery.

[0024] (4) The 3D iron-sulfur-phosphorus porous functional material of the present invention is used as a filler for deep denitrification and phosphorus recovery. It is not only a carrier for the attachment of autotrophic microorganisms and nano-zero-valent sulfur, but also a neutralizing material (containing calcium-containing clay mineral materials) for the acid production of nano-zero-valent sulfur and the oxidation acid production of autotrophic microorganisms. It not only provides the alkalinity and inorganic carbon source required for sulfur autotrophic metabolism, but also stabilizes the pH value to create a microenvironment conducive to the metabolism and reproduction of microorganisms. Its biochemical reaction equation is:

[0025] The chemical equation for the acid production process of the autotrophic denitrification reaction of the 3D iron, sulfur and phosphorus porous functional material is:

[0026] 6NO3 - +5S+2H2O=3N2+5SO4 2- +4H +

[0027] The 3D iron-sulfur-phosphorus porous functional material neutralizes the acid, and the chemical reaction equation is:

[0028] CaCO3+2H + =Ca 2+ +CO2+H2O

[0029] CaMg(CO3)2+4H +=2CO2+2H2O+Ca 2+ +Mg 2+

[0030] (5) The 3D iron, sulfur and phosphorus porous functional material prepared by the present invention is applied to the situation where the carbon source is insufficient in urban sewage treatment plants and the efficiency of phosphorus recovery is low, and the process of heterotrophic denitrification and phosphorus recovery cannot be completed. It is a supplement to the existing water treatment functional materials. Using the 3D iron, sulfur and phosphorus porous functional material as a carrier of microorganisms and a crystal seed for phosphorus crystallization, the 3D iron, sulfur and phosphorus porous functional material can achieve autotrophic denitrification of the 3D iron, sulfur and phosphorus porous functional material in conjunction with heterotrophic denitrification of organic matter, which can enhance the phosphorus recovery effect. The 3D iron, sulfur and phosphorus porous functional material prepared by the present invention has a large adsorption capacity for phosphorus (>100mg / g). Compared with the use of flocculants, the present invention avoids the introduction of redundant or even harmful anions.

[0031] (6) The formation process of cyanite can be summarized into four factors: ① the presence of high concentrations of iron and phosphorus in the water; ② the presence of reducing water environment conditions (redox potential <-300mV); ③ the presence of relatively rich organic matter (providing carbon sources for heterotrophic microorganisms such as metal-reducing bacteria); and ④ the pH condition of 6-9. The 3D iron-sulfur-phosphorus porous functional material prepared by the present invention does not need to be under the action of heterotrophic iron-reducing bacteria to achieve cyanite (K sp =10 -36 ) recovery, the standard electrode potential E of 3D iron-sulfur-phosphorus porous functional materials 0 (Fe(II) / Fe(0)) is less than the redox potential <-440mV and forms cyanite with phosphate in water. In the present invention, the 3D iron-sulfur-phosphorus porous functional material forms cyanite during sewage or sewage treatment, and the reaction equation is:

[0032] Fe 0 +2H + =Fe 2+ +H2↑

[0033] Fe(OH)3+3H + +e - =3H2O+Fe 2+

[0034] 3Fe 2+ +2PO4 3- +8H2O=Fe3(PO4)2·8H2O

[0035] 3Fe 2+ +2HPO4 2- +8H2O=Fe3(PO4)2·8H2O+2H +

[0036] Finally, the present invention also proposes a preparation method of a wastewater treatment functional material, namely a 3D hematite composite phosphorus functional material, which is made of 80-94% natural blue iron ore and natural limonite, 4-14% binder and 0.1-6% porogen. First, the natural blue iron ore and natural limonite are crushed to obtain a powder with a particle size of 0.0075 mm, and then the materials are weighed according to the mass percentage and mixed evenly, and 20-40% of water of the total mass of the mixture is added and stirred evenly, and then the water is dried. The material is printed using 3D printing technology to prepare 3D composite particles with a particle size of 1-20 mm. Finally, the 3D composite particles are calcined in a muffle furnace at 400-1000°C for 1-4 hours to obtain the 3D hematite composite phosphorus functional material.

[0037] The 3D hematite composite phosphorus functional material is loaded into the anaerobic biofilter reactor and inoculated with anaerobic bacterial liquid mainly composed of Feammox microorganisms and dissimilatory iron-reducing bacteria. Under anaerobic conditions, Feammox microorganisms and dissimilatory iron-reducing bacteria use the trivalent iron in the 3D hematite composite phosphorus functional material as an electron acceptor. The trivalent iron is reduced to divalent iron, which combines with phosphate in the water and directly oxidizes ammonia nitrogen into nitrogen gas. At the same time, under the action of the 3D hematite composite phosphorus functional material as a crystal seed, the simultaneous removal and recovery of phosphorus is enhanced, and finally blue iron ore is formed to simultaneously oxidize ammonia nitrogen, thereby realizing the recovery of phosphorus and the removal of ammonia nitrogen in wastewater. The water treatment technology solution of the 3D hematite composite phosphorus functional material using iron anaerobic ammonia oxidation biofilter is as follows:

[0038] In the process section of a municipal sewage treatment plant, a biofilter for denitrification and phosphorus recovery is constructed. 3D hematite composite phosphorus functional materials are added to the biofilter as electron acceptors, carriers, and seeds for phosphorus recovery crystallization for iron anaerobic ammonium oxidation. Before the biofilter is started, the 3D hematite composite phosphorus functional materials are grown as biofilms. The 3D hematite composite phosphorus functional materials are then loaded into the biofilter using wastewater to be denitrified and phosphorus recovered (e.g., wastewater containing high concentrations of nitrogen and phosphorus). Prior to startup, the main steps for biofilm cultivation in the 3D hematite composite phosphorus functional material-iron anaerobic ammonium oxidation biofilter are as follows:

[0039] (A) 3D hematite composite phosphorus functional materials are loaded into a biofilter that requires denitrification and phosphorus recovery. Sludge containing iron anaerobic ammonium oxidizing microorganisms or iron anaerobic ammonium oxidizing culture fluid is added to the biofilter, accounting for 0.1-30% of the volume of the biofilter. A high-power peristaltic pump is used to pump the water flowing out of the denitrification and phosphorus recovery filter outlet. Since the water contains a large amount of iron anaerobic ammonium oxidizing bacteria, the water is then transported back to the water inlet. The water is circulated in and out according to a hydraulic retention time of 1-10 hours. After a period of microbial acclimation, the iron anaerobic ammonium oxidizing bacteria will grow and multiply, and attach to the surface of the 3D hematite composite phosphorus functional material and form biofilms in the internal pores, so that the 3D hematite composite phosphorus functional material is loaded with a large amount of iron anaerobic ammonium oxidizing bacteria.

[0040] (B) During the start-up process of anaerobic ammonium oxidizing bacteria biofilm formation, the TN, TP, and COD concentrations in the inlet and outlet waters were monitored. By adding ammonium chloride, potassium dihydrogen phosphate, and glucose, the inlet TN concentration was adjusted to 5-500 mg / L, the phosphorus concentration was 5-50 mg / L, and the COD concentration was 1-10 mg / L. The inlet and outlet waters were circulated, and the anaerobic ammonium oxidizing bacteria biofilms matured after 2-20 days of culture. Alternatively, the anaerobic ammonium oxidizing bacteria biofilms matured when the effluent TN concentration was less than 2 mg / L, the TP concentration was less than 2 mg / L, and the COD concentration was less than 2 mg / L. The hydraulic retention time was adjusted between 1-4 hours to gradually bring the effluent TN, TP, and COD to Class II of the surface water environmental quality standard, achieving nitrogen removal and phosphorus recovery.

[0041] The preparation and application of the 3D hematite composite phosphorus functional material proposed in the present invention have the following beneficial effects:

[0042] (1) The 3D hematite composite phosphorus functional material prepared by the present invention has porous hematite and phosphorus as its main components and has the characteristics of large specific surface area, high porosity, and large microbial loading capacity. The 3D hematite composite phosphorus functional material serves as a carrier for Feammox microorganisms and a shuttle for microbial electrons. It also serves as an electron acceptor for anaerobic microorganisms and a seed for phosphate recovery. The 3D hematite composite phosphorus functional material can promote the activity of Feammox microorganisms and dissimilatory iron-reducing bacteria, and can achieve simultaneous recovery of phosphorus and removal of nitrogen from wastewater.

[0043] (2) The 3D hematite composite phosphorus functional material prepared by the present invention is loaded into a fixed bed reactor in a natural stacking manner. After the microorganisms form biofilms, different microbial zones are formed in different parts of the fixed bed reactor. The dissolved oxygen concentration in the upper part of the reactor is high, which is mainly due to the aerobic microbial metabolism of organic pollutants and nitrification of ammonia nitrogen. From the middle to the bottom, the microorganisms gradually transition from facultative bacteria to anaerobic bacteria, Feammox microorganisms and dissimilatory iron-reducing bacteria. These bacteria can reduce trivalent iron to divalent iron and simultaneously oxidize ammonia nitrogen. At this time, under the induction of crystal seeds, divalent iron quickly enriches phosphorus in the wastewater, phosphate (PO4 3- ) and Fe formed by biological reduction 2+ Combining with the 3D hematite composite phosphorus functional material can generate blue iron ore crystals, which can be recycled as phosphate fertilizer. This 3D hematite composite phosphorus functional material can solve the problem of low efficiency of traditional Feammox oxidation process and simultaneous denitrification and phosphorus recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Actual pictures of different materials.

[0045] Figure 2 This is the XRD diagram of nano-minerals and prepared functional materials.

[0046] Figure 3 This is the SEM image of sulfur.

[0047] Figure 4 This is the SEM image of natural blue iron ore.

[0048] Figure 5 This is the SEM image of natural blue iron ore calcined at 700℃ in hydrogen atmosphere.

[0049] Figure 6 This is the SEM image of natural limonite.

[0050] Figure 7 This is the SEM image of natural limonite calcined at 700℃ in hydrogen atmosphere.

[0051] Figure 8 This is the SEM image of attapulgite clay.

[0052] Figure 9 This is the SEM image of the 3D iron-sulfur-phosphorus porous functional material.

[0053] Figure 10 This is the SEM image of 3D hematite composite phosphorus functional material.

[0054] Figure 11 SEM image of 3D iron-sulfur-phosphorus porous functional material loaded with denitrifying Thiobacillus. DETAILED DESCRIPTION

[0055] The present invention provides a preparation method for a wastewater treatment functional material, namely a 3D iron-sulfur-phosphorus porous functional material. The material is prepared from 80-95% natural violet iron ore and natural limonite, 4-14% binder, 0.1-10% porogen, and 0.1-10% sulfur. First, the natural violet iron ore, natural limonite, porogen, binder, and sulfur are crushed to obtain a powder with a particle size of 0.0075 mm. The natural violet iron ore powder and the natural limonite powder are then calcined at 400-1000°C for 1-4 hours under a hydrogen atmosphere to obtain a nano-zero-valent iron-phosphorus composite material and a nano-zero-valent iron composite material, respectively. Then, the nano-zero-valent iron-phosphorus composite material, the nano-zero-valent iron composite material, the binder powder, the porogen powder, and the sulfur powder are uniformly mixed according to mass percentage. Finally, the mixture is weighed and printed using 3D printing technology to prepare a 3D iron-sulfur-phosphorus porous functional material with a particle size of 1-20 mm.

[0056] The present invention provides a preparation method of a wastewater treatment functional material, namely a 3D hematite composite phosphorus functional material. The material is prepared from 80-94% of natural violet iron ore and natural limonite, 4-14% of a binder, and 0.1-6% of a porogen. First, the natural violet iron ore and natural limonite are crushed to obtain a powder with a particle size of 0.0075 mm. Then, the materials are weighed according to mass percentage and mixed evenly. Water accounting for 20-40% of the total mass of the mixture is added, stirred evenly, and then the water is dried. The material is printed using 3D printing technology to prepare 3D composite particles with a particle size of 1-20 mm. Finally, the 3D composite particles are calcined in a muffle furnace at 400-1000° C. for 1-4 hours to obtain the 3D hematite composite phosphorus functional material.

[0057] The natural minerals used in the present invention and the functional materials prepared are as follows Figure 1 As shown, A is natural limonite, B is natural blue iron ore, C is 3D hematite composite phosphorus functional material, and D is 3D iron-sulfur-phosphorus porous functional material.

[0058] The natural minerals used in the present invention and the 3D iron-sulfur-phosphorus porous functional materials and 3D hematite composite phosphorus functional materials prepared are characterized by their physical phases, structural morphologies, and structures as follows:

[0059] Figure 2 The XRD diagram of nano minerals and functional materials. Figure 2 (A) is the XRD diagram of natural violet iron ore. It can be seen from the figure that the characteristic diffraction peak of violet iron ore is strong in the range of 5°-70°, indicating that the natural violet iron ore has high crystallinity. Figure 2 (B) is the XRD pattern of sepiolite and kaolin. It can be seen from the figure that the characteristic diffraction peaks of sepiolite and kaolin appear in the range of 3°-70°, indicating that sepiolite and kaolin have high crystallinity. Figure 2 (C) shows the XRD patterns of the 3D porous iron-sulfur-phosphorus functional material and the 3D hematite-composite phosphorus functional material. The functional materials prepared in Examples 1 and 2 are 3D porous iron-sulfur-phosphorus functional materials, and the patterns show the presence of characteristic diffraction peaks of nano-zero-valent iron. The functional materials prepared in Examples 5 and 6 are 3D hematite-composite phosphorus functional materials, and the patterns show the presence of characteristic diffraction peaks of hematite.

[0060] Figure 3 The SEM images of sulfur are shown in Figure 1. AD represents different magnifications. As can be seen from the figure, the sulfur has dense particles and low porosity, resulting in a low sulfur dissolution rate and a large, blocky morphology.

[0061] Figure 4 These are SEM images of natural violet iron ore. AD represents different magnifications. The images show that violet iron ore has nanoparticle morphology, plate-like, and flocculent nanostructures. Natural violet iron ore has a dense structure and low activity.

[0062] Figure 5 This is a SEM image of natural violet calcined at 700°C in a hydrogen atmosphere. AD represents different magnifications. The image shows the removal of structural water, crystal water, zeolitic water, and adsorbed water from the natural violet, forming a nanostructured Fe° / P composite porous material with high porosity and large specific surface area. This highly active material can serve as a seed crystal for phosphorus recovery and an electron donor for sulfur-autotrophic denitrifying bacteria, achieving simultaneous denitrification and phosphorus recovery.

[0063] Figure 6 This is a SEM image of natural limonite. AD represents different magnifications. As can be seen from the image, natural limonite is a crystalline mineral composed of multiple minerals, including goethite, hematite, and siderite, with a nano-needle-like structure.

[0064] Figure 7 These are SEM images of natural limonite calcined at 700°C in a hydrogen atmosphere. AD represents different magnifications. The images show that the natural limonite exhibits a nanostructured porous structure with a large specific surface area, porosity, and high activity.

[0065] Figure 8 These are SEM images of attapulgite clay. AD represents different magnifications. The images show that attapulgite clay exhibits a nanorod-like morphology with a disordered arrangement, high activity, and a large specific surface area.

[0066] Figure 9 These are SEM images of the 3D iron-sulfur-phosphorus porous functional material. AD represents different magnifications. As can be seen from the image, the 3D iron-sulfur-phosphorus porous functional material, fabricated using 3D printing technology, has an open pore structure and a coral-like morphology. Anaerobic microorganisms can attach and grow on both the inner and outer surfaces, exhibiting affinity for microorganisms and a large specific surface area.

[0067] Figure 10 These are SEM images of the 3D hematite-composite phosphorus-functional material. AD represents different magnifications. As can be seen from the image, the 3D hematite-composite phosphorus-functional material has an open pore structure, a large specific surface area, and high activity. Iron-ammonia-oxidizing bacteria can enter the material through the open pore structure and reproduce and grow.

[0068] Figure 11 SEM images of the 3D iron-sulfur-phosphate porous functional material loaded with denitrifying Thiobacillus. AE represents different magnifications. After approximately six months of operation, the 3D iron-sulfur-phosphate porous functional material exhibited a significant presence of denitrifying Thiobacillus, filamentous bacteria, and aerobic microorganisms on its inner and outer surfaces, demonstrating its hydrophilic nature and suitability for microbial growth.

[0069] The following is a detailed explanation of the functional material for wastewater treatment prepared based on natural blue iron ore and natural limonite, the preparation method, and the application in simultaneous denitrification and phosphorus recovery proposed by the present invention in conjunction with the embodiments.

[0070] 1. Preparation and application of 3D iron-sulfur-phosphorus porous functional materials

[0071] Example 1

[0072] (1) First, natural violet iron ore, natural limonite, attapulgite clay, sawdust and sulfur were crushed to obtain a powder with a particle size of 0.0075 mm. Then, the natural violet iron ore powder and the natural limonite powder were calcined at 800 °C for 2 h in a hydrogen atmosphere to obtain nano zero-valent iron-phosphorus composite materials and nano zero-valent iron composite materials, respectively.

[0073] (2) Then, according to the mass percentages of nano zero-valent iron phosphorus functional material, nano zero-valent iron composite material, attapulgite clay powder, sawdust powder and sulfur powder as follows: nano zero-valent iron phosphorus functional material 63%, nano zero-valent iron composite material 25%, attapulgite powder 5%, sawdust 2% and sulfur powder 5%, the materials were mixed evenly, and finally the mixture was weighed and 3D printing technology was used to print and prepare a 3D iron sulfur phosphorus porous functional material with a particle size of 4-8 mm and a specific surface area of 175 m 2 / g, porosity of 87%, and redox potential of -500MV.

[0074] (3) An inverted cone-shaped container was constructed using acrylic glass as an anoxic denitrification and phosphorus recovery biofilter. An acrylic glass tube was installed at the bottom as the water inlet and at the top as the water outlet. The inverted cone structure design allows the 3D iron, sulfur, and phosphorus porous functional material and microbial composite flocs to be retained in the denitrification and phosphorus recovery tank, reducing the loss of the 3D iron, sulfur, and phosphorus porous functional material and microorganisms and lowering the turbidity of the effluent.

[0075] (4) Nitrate, potassium dihydrogen phosphate and glucose were added to tap water to prepare simulated wastewater for the experiment and stored in a water storage tank. The concentration of nitrate nitrogen was 50 mg / L, the concentration of phosphorus was 20 mg / L and the concentration of COD was 6 mg / L.

[0076] (5) Using a peristaltic pump, inject simulated wastewater into the anoxic denitrification and phosphorus recovery filter, add the 3D iron-sulfur-phosphorus porous functional material prepared in step (2) and the enriched sulfur autotrophic denitrification bacteria liquid accounting for 20% of the volume of the denitrification and phosphorus recovery pool.

[0077] (6) The effluent from the upper part of the denitrification and phosphorus recovery pool is transported from the lower water inlet to the denitrification and phosphorus recovery filter tank by a peristaltic pump to form a water cycle, and heterotrophic and autotrophic microorganisms are domesticated and cultured, and composite flocs are formed with the 3D iron-sulfur-phosphorus porous functional material until the TN concentration is <5 mg / L, the effluent concentration of TP is <1 mg / L, and the effluent concentration of COD is <1 mg / L, which is considered to be mature.

[0078] (7) The flow rate was adjusted to gradually reduce the hydraulic retention time in the anoxic denitrification and phosphorus recovery reactor to less than 1 h. The TN, TP, and COD ion concentrations of the effluent were monitored daily. When the TN concentration of the effluent was lower than 0.01 mg / L, the phosphorus concentration was lower than 0.02 mg / L, and the COD concentration was lower than 0.01 mg / L, the denitrification and phosphorus recovery filter reached a stable state, and the final blue iron ore recovery product was obtained. The effluent met the surface water environmental quality standard Class II.

[0079] Example 2

[0080] (1) First, natural violet iron ore, natural limonite, sepiolite clay, straw debris and sulfur were crushed to obtain a powder with a particle size of 0.0075 mm. Then, the natural violet iron ore powder and the natural limonite powder were calcined at 700 °C for 3 h in a hydrogen atmosphere to obtain nano-zero-valent iron-phosphorus composite materials and nano-zero-valent iron composite materials, respectively.

[0081] (2) Then, according to the mass percentages of nano-zero-valent iron-phosphorus composite material, nano-zero-valent iron composite material, sepiolite clay powder, straw powder and sulfur powder as follows: nano-zero-valent iron-phosphorus functional material 60%, nano-zero-valent iron composite material 32%, sepiolite powder 4%, straw powder 1% and sulfur powder 3%, the materials were mixed evenly, and finally the mixture was weighed and printed using 3D printing technology to prepare a 3D iron-sulfur-phosphorus porous functional material with a particle size of 3-10 mm and a specific surface area of 183 m 2 / g, porosity of 76%, and redox potential of -550MV.

[0082] (3) An inverted cone-shaped container was constructed using acrylic glass as an anoxic denitrification and phosphorus recovery biofilter. An acrylic glass tube was installed at the bottom as the water inlet and at the top as the water outlet. The inverted cone structure design allows the 3D iron, sulfur, and phosphorus porous functional material and microbial composite flocs to be retained in the denitrification and phosphorus recovery tank, reducing the loss of the 3D iron, sulfur, and phosphorus porous functional material and microorganisms and lowering the turbidity of the effluent.

[0083] (4) Nitrate, potassium dihydrogen phosphate and glucose were added to tap water to prepare simulated wastewater for the experiment and stored in a water storage tank. The concentration of nitrate nitrogen was 30 mg / L, the concentration of phosphorus was 30 mg / L and the concentration of COD was 5 mg / L.

[0084] (5) Using a peristaltic pump, inject simulated wastewater into the anoxic denitrification and phosphorus recovery filter, add the 3D iron-sulfur-phosphorus porous functional material prepared in step (2) and the enriched sulfur autotrophic denitrification bacteria liquid accounting for 10% of the volume of the denitrification and phosphorus recovery pool.

[0085] (6) The effluent from the upper part of the denitrification and phosphorus recovery pool is transported from the lower water inlet to the denitrification and phosphorus recovery filter tank by a peristaltic pump to form a water cycle, and heterotrophic and autotrophic microorganisms are domesticated and cultured, and composite flocs are formed with the 3D iron-sulfur-phosphorus porous functional material until the TN concentration is <5 mg / L, the effluent concentration of TP is <2 mg / L, and the effluent concentration of COD is <2 mg / L, which is considered to be mature.

[0086] (7) The flow rate was adjusted to gradually reduce the hydraulic retention time in the anoxic denitrification and phosphorus recovery reactor to less than 0.5 h. The TN, TP, and COD ion concentrations of the effluent were monitored daily. When the TN concentration of the effluent was lower than 0.01 mg / L, the phosphorus concentration was lower than 0.02 mg / L, and the COD concentration was lower than 0.01 mg / L, the denitrification and phosphorus recovery filter reached a stable state, and the final blue iron ore recovery product was obtained. The effluent met the surface water environmental quality standard Class II.

[0087] Example 3

[0088] (1) First, natural blue iron ore, natural limonite, kaolin, pulp fiber and sulfur were crushed to obtain a powder with a particle size of 0.0075 mm. Then, the natural blue iron ore powder and the natural limonite powder were calcined at 600 °C for 2 h in a hydrogen atmosphere to obtain nano zero-valent iron-phosphorus composite materials and nano zero-valent iron composite materials, respectively.

[0089] (2) Then, according to the mass percentages of nano-zero-valent iron-phosphorus composite material, nano-zero-valent iron composite material, kaolin powder, pulp fiber powder and sulfur powder as follows: nano-zero-valent iron-phosphorus functional material 75%, nano-zero-valent iron composite material 17%, kaolin powder 2%, pulp fiber powder 3% and sulfur powder 3%, the materials were mixed evenly, and finally the mixture was weighed and printed using 3D printing technology to prepare a 3D iron-sulfur-phosphorus porous functional material with a particle size of 10-15 mm and a specific surface area of 215 m 2 / g, porosity of 83%, and redox potential of -650MV.

[0090] (3) An inverted cone-shaped container was constructed using acrylic glass as an anoxic denitrification and phosphorus recovery biofilter. An acrylic glass tube was installed at the bottom as the water inlet and at the top as the water outlet. The inverted cone structure design allows the 3D iron, sulfur, and phosphorus porous functional material and microbial composite flocs to be retained in the denitrification and phosphorus recovery tank, reducing the loss of the 3D iron, sulfur, and phosphorus porous functional material and microorganisms and lowering the turbidity of the effluent.

[0091] (4) Nitrate, potassium dihydrogen phosphate, and glucose were added to tap water to prepare simulated wastewater for the experiment and stored in a water storage tank. The concentration of nitrate nitrogen was 20 mg / L, the concentration of phosphorus was 10 mg / L, and the concentration of COD was 7 mg / L.

[0092] (5) Using a peristaltic pump, inject simulated wastewater into the anoxic denitrification and phosphorus recovery filter, add the 3D iron-sulfur-phosphorus porous functional material prepared in step (2) and the enriched sulfur autotrophic denitrification bacteria liquid accounting for 10% of the volume of the denitrification and phosphorus recovery pool.

[0093] (6) The effluent from the upper part of the denitrification and phosphorus recovery pool is transported from the lower water inlet to the denitrification and phosphorus recovery filter tank by a peristaltic pump to form a water cycle, and heterotrophic and autotrophic microorganisms are domesticated and cultured, and composite flocs are formed with the 3D iron-sulfur-phosphorus porous functional material until the TN concentration is <3 mg / L, the effluent concentration of phosphorus is <2 mg / L, and the effluent concentration of COD is <0.1 mg / L, which is considered to be mature.

[0094] (7) The flow rate was adjusted to gradually reduce the hydraulic retention time in the anoxic denitrification and phosphorus recovery reactor to less than 2 h. The TN, TP, and COD ion concentrations of the effluent were monitored daily. When the TN concentration of the effluent was lower than 0.01 mg / L, the phosphorus concentration was lower than 0.02 mg / L, and the COD concentration was lower than 0.01 mg / L, the denitrification and phosphorus recovery filter reached a stable state, and the final blue iron ore recovery product was obtained. The effluent met the surface water environmental quality standard Class II.

[0095] Comparative Example 4

[0096] (1) Natural limonite and natural blue iron ore were crushed to obtain particles of 1-10 mm, among which the specific surface area of natural limonite was 12 m 2 / g, the specific surface area of natural blue iron ore is 14m 2 / g.

[0097] (2) Natural limonite and natural blue iron ore were crushed to obtain particles of 1-10 mm, and these particles were reduced and calcined at 700 ° C for 2 h in a hydrogen atmosphere to obtain nano zero-valent iron composite fillers and nano zero-valent Fe ° / P composite fillers, wherein the nano zero-valent iron composite filler has a specific surface area of 23m 2 / g, the specific surface area of nano zero-valent Fe ° / P composite filler is 25m 2 / g.

[0098] (3) Sulfur flake particles + calcium-containing attapulgite particles are mixed (mass ratio 1:1), sulfur paste particles + calcium-containing attapulgite particles are mixed (mass ratio 1:1), pyrite particles + calcium-containing attapulgite particles are mixed (mass ratio 1:1), and pyrrhotite particles + calcium-containing attapulgite particles are mixed (mass ratio 1:1) to obtain four mixed mineral materials.

[0099] (4) Purchase commercially available porous autotrophic denitrification fillers.

[0100] (5) Nine inverted cone-shaped containers were made of acrylic glass as anoxic denitrification and phosphorus recovery biofilters, with an acrylic glass tube installed at the bottom as the water inlet and an acrylic glass tube installed at the top as the water outlet. The inverted cone structure design allows the iron-containing nano-mineral materials prepared in (1), (2) and (3) and the purchased porous autotrophic denitrification filler and microbial composite flocs (4) to be retained in the denitrification and phosphorus recovery tank, reducing the loss of materials and microorganisms and reducing the turbidity of the effluent.

[0101] (6) Nitrate, potassium dihydrogen phosphate, and glucose were added to tap water to prepare simulated wastewater for the experiment and stored in a water storage tank. The nitrate nitrogen concentration was 30 mg / L, the phosphorus concentration was 30 mg / L, and the COD concentration was 5 mg / L.

[0102] (7) Parallel comparative experiments were set up: simulated wastewater and enriched sulfur autotrophic denitrification bacteria solution accounting for 20% of the volume of the denitrification and phosphorus recovery pool were injected into the anoxic denitrification and phosphorus recovery pool using a peristaltic pump.

[0103] (8) The effluent from the upper part of the denitrification and phosphorus recovery pool is transported from the lower water inlet to the denitrification and phosphorus recovery filter pool by a peristaltic pump to form a water cycle, domesticate and cultivate heterotrophic and autotrophic microorganisms, and form composite flocs with (1), (2) and (3) functional materials and (4) commercially available porous autotrophic denitrification fillers.

[0104] (9) The flow rate was adjusted to gradually reduce the hydraulic retention time in the anoxic denitrification and phosphorus recovery reactor to less than 1 h. The effluent TN, TP, and COD concentrations were monitored daily. Table 1 shows the effluent concentration data after 6 months of operation. It can be seen from the following table that the nitrogen and phosphorus concentrations of the effluents of all the comparison materials were much higher than the surface water environmental quality discharge standards.

[0105] Table 1 TN, TP, COD effluent concentration test data after 6 months of operation of comparative example 4

[0106]

[0107] 2. Preparation and application of 3D hematite composite phosphorus functional materials

[0108] Example 5

[0109] (1) Crushing natural limonite and natural blue iron ore to obtain powder with a particle size of 0.0075 mm, weighing the materials according to the following mass percentages of natural limonite, natural blue iron ore, attapulgite clay, and pulp fiber: 66% natural blue iron ore powder, 25% natural limonite powder, 8% attapulgite clay, and 1% pulp fiber, and mixing them evenly. Adding 25% water by mass of the mixture and stirring evenly, drying the water, and using 3D printing technology to print and prepare 3D composite particles with a particle size of 1-20 mm, finally placing the 3D composite particles in a muffle furnace and calcining them at 600 ° C for 4 h. The obtained 3D hematite composite phosphorus functional material has a specific surface area of 170 m 2 / g, and the porosity is 65%.

[0110] (2) The control group experiment used natural limonite, natural hematite, natural magnetite, and natural siderite as fillers. The preparation method was as follows: crush the natural limonite, natural hematite, natural magnetite, and natural siderite separately to obtain 3-10 mm particles. The specific surface areas of the four materials were: 10 m 2 / g、12m 2 / g、19m 2 / g and 13m 2 / g.

[0111] (3) The prepared 3D hematite composite phosphorus functional material and the control group material in (2) were loaded into experimental water treatment columns of the same size, and iron-ammonia oxidizing bacteria were inoculated and cultured to enrich the culture. The ODP value of the bacterial solution was greater than 0.5. The bacterial solution volume was 2% of the experimental column volume. The culture solution in the experimental column was circulated by a peristaltic pump for 2-3 days to promote the formation of iron-ammonia oxidizing bacteria on the surface and inside of the 3D hematite composite phosphorus functional material. Then, the water treatment was started under normal conditions. The initial influent concentration was controlled to be 300 mg / L ammonia nitrogen concentration, 30 mg / L phosphorus concentration, 3 mg / L COD concentration, and 1 day hydraulic retention time.

[0112] (4) After approximately 6 months of operation, the concentrations of TN, TP, and COD were monitored daily. If the effluent did not meet the discharge or water resource requirements, it would indicate that the electrons provided by the 3D hematite composite phosphorus functional material were ineffective or the adsorption and phosphorus removal capacity was saturated. Blue iron ore recovery products could be obtained and applied to the production of agricultural phosphate fertilizers.

[0113] Table 2 TN and TP effluent concentration test data after 6 months of operation of Example 5 and control experiment

[0114]

[0115] Example 6

[0116] (1) Crushing natural limonite and natural blue iron ore to obtain powder with a particle size of 0.0075 mm, weighing the materials and mixing them evenly according to the mass percentage of natural limonite, natural blue iron ore, sepiolite and leaf debris as follows: natural blue iron ore 57%, natural limonite 30%, sepiolite 10%, leaf debris 3%, adding 25% water by mass ratio of the mixed materials, stirring evenly and drying the water, and using 3D printing technology to print and prepare 3D composite particles with a particle size of 1-20 mm, and calcining the 3D composite particles at 800 ° C in a muffle furnace for 3 hours. The specific surface area of the prepared 3D hematite composite phosphorus functional material is 180m 2 / g, and the porosity is 73%.

[0117] (2) Control group experiment: Brown-porous hematite, red-porous hematite, magnetic-porous hematite, and rhombohedral-porous hematite were used as fillers. The preparation method was as follows: crush natural brown iron ore, natural hematite, natural magnetite, and natural siderite to obtain 4-10 mm granular materials, and calcine them at 300 ° C in a muffle furnace for 2 h. The specific surface areas of the four materials were as follows: brown-porous hematite was 25 m 2 / g, hematite-porous hematite is 22m 2 / g, magnetic-porous hematite is 29m 2 / g, rhombohedral-porous hematite is 23m 2 / g.

[0118] (3) The prepared 3D hematite composite phosphorus functional material and the material prepared in the control group experiment in (2) were loaded into an experimental water treatment column of the same size and inoculated with iron-ammonia oxidizing bacteria to enrich and culture the bacterial solution. The ODP value of the bacterial solution was greater than 0.3. The bacterial solution volume was 2% of the experimental column volume. The culture solution in the experimental column was circulated by a peristaltic pump for 5-7 days to promote the formation of iron-ammonia oxidizing bacteria on the surface and inside of the 3D hematite composite phosphorus functional material. Then, the water treatment was started under normal conditions. The initial influent ammonia nitrogen concentration was controlled to be 400 mg / L, phosphorus concentration was 50 mg / L, COD concentration was 4 mg / L, and hydraulic retention time was 2 days.

[0119] (4) After approximately 6 months of operation, the concentrations of TN, TN, and COD were monitored daily. When the effluent failed to meet the discharge or water resource requirements, it indicated that the electrons provided by the 3D hematite composite phosphorus functional material had failed or the adsorption and phosphorus removal capacity was saturated. Blue iron ore recovery products could be obtained and applied to the production of agricultural phosphate fertilizers.

[0120] Table 3 TN and TP effluent concentration test data after 6 months of operation of Example 6 and control experiment

[0121]

[0122] Example 7

[0123] (1) Crushing natural limonite and natural blue iron ore to obtain powder with a particle size of 0.0075 mm, weighing the materials and mixing them evenly according to the mass percentage of natural limonite, natural blue iron ore, bentonite and straw debris as follows: natural blue iron ore powder 68%, natural limonite 25%, bentonite 6% and straw debris 1%. Adding 25% water by mass ratio to the mixture and stirring evenly, drying the water, 3D printing technology was used to prepare 3D composite particles with a particle size of 1-20 mm. Finally, the 3D composite particles were calcined at 900 ° C in a muffle furnace for 2 hours. The specific surface area of the prepared 3D hematite composite phosphorus functional material is 186 m 2 / g, and the porosity is 92%.

[0124] (2) Control group experiment: Concave-iron oxide porous ceramsite, sea-iron oxide porous ceramsite, expanded-iron oxide porous ceramsite, and high-iron oxide porous ceramsite were used as fillers respectively. The preparation method was as follows: attapulgite, straw, goethite (mass ratio: 10:1:5); sepiolite, sawdust, hematite (mass ratio: 10:1:5); bentonite, leaves, magnetite (mass ratio: 10:1:5); kaolin, siderite, dry cyanobacteria (mass ratio: 10:1:5) were mixed in total to obtain attapulgite-goethite composite, sepiolite-hematite composite, bentonite-magnetite composite, and kaolin-siderite composite. The fillers were calcined at 900℃ for 2h in air atmosphere to obtain concave-iron oxide porous ceramsite, sea-iron oxide porous ceramsite, expanded-iron oxide porous ceramsite, and high-iron oxide porous ceramsite.

[0125] (3) The prepared 3D hematite composite phosphorus functional material and the material prepared in the control group experiment in (2) were loaded into an experimental water treatment column of the same size, and iron-ammonia oxidizing bacteria were inoculated and enriched, and the bacterial solution ODP value was greater than 0.5. The bacterial solution volume was 2% of the experimental column volume. The culture solution in the experimental column was circulated by a peristaltic pump for 2-3 days to promote the formation of iron-ammonia oxidizing bacteria on the surface and inside of the 3D hematite composite phosphorus functional material and the material in (2). Then, water treatment was started under normal conditions. The initial influent concentration was controlled to be 500 mg / L ammonia nitrogen concentration, 5 mg / L phosphorus concentration, 4 mg / L COD concentration, and 3 days hydraulic retention time.

[0126] (4) After approximately 6 months of operation, the effluent concentrations of TN, TP, and COD were monitored daily. If the effluent did not meet the discharge or water resource requirements, it would indicate that the electrons provided by the 3D hematite composite phosphorus functional material were ineffective or the adsorption and phosphorus removal capacity was saturated. Blue iron ore recovery products could be obtained and applied to the production of agricultural phosphate fertilizers.

[0127] Table 4 Total nitrogen and phosphorus effluent concentration detection data after 6 months of operation of Example 7 and control experiment

[0128]

[0129] Example 8

[0130] (1) Crushing natural limonite and natural blue iron ore to obtain powder with a particle size of 0.0075 mm, weighing the materials according to the following mass percentages of natural limonite, natural blue iron ore, water glass and pulp fiber: natural blue iron ore powder 60%, natural limonite 26%, water glass 12% and pulp fiber 2%, adding 25% water by mass ratio of the mixed materials, stirring evenly and drying the water, and then printing it by 3D printing technology to prepare 3D composite particles with a particle size of 1-20 mm, and calcining the 3D composite particles at 650 ° C in a muffle furnace for 4 hours. The specific surface area of the prepared 3D hematite composite phosphorus functional material is 198m 2 / g, and the porosity is 95%.

[0131] (2) The control group experiment used commercially available iron-containing porous ceramsite as filler.

[0132] (3) The prepared 3D hematite composite phosphorus functional material and the commercially available iron-containing porous ceramsite in (2) were used as fillers and loaded into an experimental water treatment column of the same size. Iron-ammonia oxidizing bacteria were inoculated and enriched, and the bacterial solution ODP value was greater than 0.5. The bacterial solution volume was 2% of the experimental column volume. The culture solution in the experimental column was circulated by a peristaltic pump for 2-3 days to promote the formation of iron-ammonia oxidizing bacteria on the surface and inside of the 3D hematite composite phosphorus functional material. Then, water treatment was started under normal conditions. The initial influent ammonia nitrogen concentration was controlled to be 450 mg / L, phosphorus concentration was 10 mg / L, COD concentration was 5 mg / L, and hydraulic retention time was 0.5 days.

[0133] (4) After approximately 6 months of operation, the concentrations of TN, TP, and COD were monitored daily. If the effluent did not meet the discharge or water resource requirements, it would indicate that the electrons provided by the 3D hematite composite phosphorus functional material were ineffective or the adsorption and phosphorus removal capacity was saturated. Blue iron ore recovery products could be obtained and applied to the production of agricultural phosphate fertilizers.

[0134] Table 5 Ammonia nitrogen and phosphorus effluent concentration detection data after 6 months of operation of Example 8 and control experiment

[0135]

[0136] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A functional material for wastewater treatment prepared based on natural blue iron ore and natural limonite, characterized in that: The wastewater treatment functional material made of nano zero-valent iron-phosphorus composite material and 80-95% nano zero-valent iron composite material, 4-14% binder, 0.1-10% porogen and 0.1-10% sulfur is a 3D iron-sulfur-phosphorus porous functional material. The preparation method thereof comprises the following steps: first, natural blue iron ore, natural limonite, porogen, binder and sulfur are crushed and sieved to obtain powder; then, the natural blue iron ore powder and the natural limonite powder are calcined at 400-1000°C for 1-4h under a hydrogen atmosphere to obtain nano zero-valent iron-phosphorus composite material and nano zero-valent iron composite material, respectively; then, the nano zero-valent iron-phosphorus composite material, nano zero-valent iron composite material, binder powder, porogen powder and sulfur powder are evenly mixed according to mass percentage; finally, the mixture is weighed and printed using 3D printing technology to prepare a 3D iron-sulfur-phosphorus porous functional material with a particle size of 1-20mm.

2. The wastewater treatment functional material according to claim 1, wherein The mass ratio of the nano zero-valent iron-phosphorus composite material to the nano zero-valent iron composite material is 1-5:

1.

3. The functional material for wastewater treatment according to claim 1, wherein The porogen is selected from straw debris, leaf debris, pulp fiber or sawdust, and the binder is selected from water glass, attapulgite clay, sepiolite clay, bentonite, montmorillonite or kaolin.

4. A functional material for wastewater treatment prepared based on natural blue iron ore and natural limonite, characterized in that: A wastewater treatment functional material prepared from 80-94% natural violet iron ore and natural limonite, 4-14% binder, and 0.1-6% porogen is a 3D hematite composite phosphorus functional material. The preparation method comprises the following steps: first, crushing the natural violet iron ore and natural limonite, sieving to obtain powder, then weighing each material according to mass percentage and mixing them evenly, adding 20-40% water of the total mass of the mixture, stirring evenly, and drying the water, and then printing the mixture using 3D printing technology to prepare 3D composite particles with a particle size of 1-20 mm, and finally calcining the 3D composite particles in a muffle furnace at 400-1000° C. for 1-4 hours to obtain the 3D hematite composite phosphorus functional material.

5. The wastewater treatment functional material according to claim 4, wherein The mass ratio of natural blue iron ore to natural limonite is 1-5:

1.

6. The wastewater treatment functional material according to claim 4, wherein: The porogen is selected from straw debris, leaf debris, pulp fiber or sawdust, and the binder is selected from water glass, attapulgite clay, sepiolite clay, bentonite, montmorillonite or kaolin.

7. The use of the wastewater treatment functional material in simultaneous denitrification and phosphorus recovery according to claim 1, characterized in that: The 3D iron-sulfur-phosphorus porous functional material is added to wastewater that requires deep denitrification and phosphorus recovery. It acts as an electron donor in the sulfur autotrophic denitrification and phosphorus recovery filter, reducing nitrate nitrogen to nitrogen gas to achieve denitrification. At the same time, ferrous ions combine with phosphorus in the water body. Under the conditions of rich phosphorus, redox potential <-300mV and pH 6-9, blue iron ore is rapidly formed under the induction of phosphorus-containing crystal seeds and the drive of the 3D iron-sulfur-phosphorus porous functional material, achieving simultaneous denitrification and phosphorus recovery.

8. The use of the wastewater treatment functional material in simultaneous denitrification and phosphorus recovery as claimed in claim 4, characterized in that: The 3D hematite composite phosphorus functional material is loaded into an anaerobic iron-ammonia oxidation reactor, and an anaerobic bacterial liquid mainly composed of Feammox microorganisms and dissimilatory iron-reducing bacteria is inoculated. Under anaerobic conditions, Feammox microorganisms and dissimilatory iron-reducing bacteria use the 3D hematite composite phosphorus functional material as a carrier, and directly oxidize ammonia nitrogen into nitrogen gas under the action of Feammox microorganisms. At the same time, trivalent iron is used as an electron acceptor to achieve trivalent iron reduction, which is combined with phosphate in the water. Under the action of phosphorus as a crystal seed, the phosphorus recovery effect is enhanced, and denitrification and phosphorus recovery in wastewater are achieved, and finally phosphorus is recovered as blue iron ore.

Images