Synchronous denitrification and phosphorus removal light material and preparation and application method thereof

Abstract

The application discloses a kind of synchronous denitrification and phosphorus removal light materials and its preparation and application method, belong to environmental functional materials and sewage treatment technical field.The application is obtained by fully melting and dispersing sulfur and iron-based component, and the iron-based component is a mixture of pyrite and calcium-magnesium carbonate.The molten mixture is foamed to form a synchronous denitrification and phosphorus removal light material.The synchronous denitrification and phosphorus removal light material has high porosity, large specific surface area, light weight and high reactivity.The light material is used as a microbial carrier and an electron donor for biochemical reactions, and is applied to fixed bed, fluidized bed and other reactors for sewage treatment.The light material has good microbial adhesion performance, high denitrification rate and good phosphorus removal effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of environmental functional materials and sewage treatment technology, and more particularly relates to a light material for simultaneous nitrogen and phosphorus removal and a preparation and application method thereof. BACKGROUND

[0002] In recent years, the rapid economic development and accelerated urbanization of the country have caused water eutrophication to become more and more serious, and the main cause of water eutrophication is the over-standard of nitrogen and phosphorus elements in water. Therefore, the deep treatment of nitrogen and phosphorus in sewage has become a focus problem of environmental protection.

[0003] At present, biological method is mainly used for sewage treatment because of its low cost and wide use. Autotrophic and heterotrophic denitrification technology is widely used for nitrogen removal in sewage, and chemical method is the most fundamental method for phosphorus removal in sewage. Since heterotrophic denitrification needs to add carbon source, there are problems such as high cost, risk of COD leakage, etc.; chemical method for phosphorus removal needs to add coagulant, and there are problems such as high cost, complex control and management, etc. In recent years, more and more researches focus on the use of natural mineral materials such as pyrrhotite and siderite for denitrification and phosphorus removal in sewage treatment, and some effects have been achieved. However, their denitrification and phosphorus removal rates are generally low, and a long hydraulic retention time is needed for denitrification and phosphorus removal, which limits their large-scale application.

[0004] At present, in the process of simultaneous nitrogen and phosphorus removal in sewage by using sulfur autotrophic denitrification, the most widely used is the "sulfur-limestone autotrophic denitrification" (SLAD) system, and its reaction chemical equation is as follows:

[0005]

[0006] The SLAD system is an autotrophic denitrification process using sulfur as an electron donor, which has the advantages of no need for additional carbon source, less sludge production, low cost, simple process, etc. The system has a high denitrification rate, but the phosphorus removal effect is not good, and there are problems of high hardness and high sulfate in the effluent. In the SLAD system, the smaller the particle size of sulfur and limestone, the larger the specific surface area, and the higher the denitrification rate. However, small particle size can cause the system to be easily blocked and unable to operate. Moreover, the limestone particles and sulfur particles can be easily layered during flushing due to the difference in density, thereby affecting the operation effect of the system after flushing.

[0007] According to the search, the patent application No. CN201010524339.3, application date October 29, 2010 discloses a method for denitrification and phosphorus removal by using pyrite as a biochemical filler, and its reaction equation is as follows:

[0008]

[0009] The biofilter has the advantages of simultaneous nitrogen and phosphorus removal, but the denitrification rate is low.

[0010] The patent application No. CN201310695460.6, application date Dec. 17, 2013, discloses a natural pyrrhotite biofilter and a method for simultaneous nitrogen and phosphorus removal using the biofilter, and the reaction equation is as follows:

[0011]

[0012] The biofilter can simultaneously remove nitrogen and phosphorus, and the denitrification rate is higher than that of the pyrite biofilter, but there is still a big gap with the SLAD. The pyrite biofilter and the pyrrhotite biofilter also have the same problem as the SLAD system, i.e. the particle size is large, and the denitrification rate is not high; the particle size can be small to improve the denitrification rate, but the system is easy to be blocked and cannot operate normally.

[0013] According to the search, the patent application No. CN201811034113.8, application date Sep. 5, 2018, discloses a coupled packing autotrophic denitrification biofilter and application, which is characterized by using natural pyrrhotite, sulfur, and limestone mixed particles as fillers, which are placed in the reactor, and after inoculation and biofilm formation, an autotrophic denitrification biofilter is formed. The biofilter combines the advantages of SLAD and pyrite biofilter, has good nitrogen and phosphorus removal effect, and to some extent, forms a synergistic effect between sulfur and pyrite biochemical reaction, and improves the nitrogen and phosphorus removal rate. However, this method only simply mixes pyrrhotite, sulfur, and limestone particles, and the synergistic effect between sulfur and pyrite biochemical reaction and their respective denitrification reactions are restricted by the particle size, which cannot be further improved. Moreover, the density difference between sulfur, limestone, and pyrite is larger, and the system is more likely to be damaged during flushing; the specific surface area of the material is small, which is not conducive to the adhesion and utilization of microorganisms, etc. SUMMARY

[0014] 1. Problem to be solved

[0015] In view of the problems of large particle size, small specific surface area, and low nitrogen removal rate of the existing reducing sulfide fillers in the sewage treatment technology, the present application provides a simultaneous nitrogen and phosphorus removal lightweight material, which is formed by highly melting sulfur and iron-based components, wherein the iron-based components are a mixture of pyrite and calcium-magnesium carbonate or pyrite; and by foaming treatment to form a lightweight material. The simultaneous nitrogen and phosphorus removal lightweight material has the advantages of high porosity, large specific surface area, light weight, high reactivity, good microbial adhesion performance, etc. Moreover, due to the high fusion of sulfur and pyrite, the H +It can accelerate the dissolution of pyrite, promote the process of pyrite autotrophic denitrification, strengthen the synergistic effect of sulfur autotrophic denitrification and pyrite autotrophic denitrification, and has a high denitrification rate and a good simultaneous phosphorus removal effect.

[0016] 2. Technical solution

[0017] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0018] The present application provides a preparation method of a simultaneous denitrification and phosphorus removal lightweight material, characterized in that: sulfur and an iron-based component are mixed to obtain a mixture, wherein the iron-based component is a mixture of pyrite and calcium-magnesium carbonate or pyrite; the mixture is heated and melted to obtain a molten mixture; and then the molten mixture is cooled and formed to obtain the simultaneous denitrification and phosphorus removal lightweight material.

[0019] Preferably, the molten mixture is subjected to foaming treatment before being cooled and formed, and the molten mixture is continuously stirred during the foaming process, and then the foamed molten mixture is cooled and formed to obtain the simultaneous denitrification and phosphorus removal lightweight material.

[0020] Preferably, the mass ratio of sulfur to the iron-based component is 6:1 to 1:2, and the mass ratio of pyrite to calcium-magnesium carbonate in the iron-based component is 1:0 to 1:4; more preferably, the mass ratio of sulfur to the iron-based component is 3:1 to 1:2, and the mass ratio of pyrite to calcium-magnesium carbonate in the iron-based component is 1:0 to 1:2.

[0021] Preferably, the foaming treatment includes physical foaming or chemical foaming.

[0022] Preferably, when the mass ratio of sulfur to the iron-based component is ≤3, physical foaming or chemical foaming is adopted for foaming; when the mass ratio of sulfur to the iron-based component is >3, only chemical foaming can be adopted for foaming.

[0023] Preferably, the molten mixture is continuously stirred during the heating and melting process, and the molten mixture is subjected to foaming treatment when the color of the molten mixture is uniform and stable, and the molten mixture is continuously stirred during the foaming treatment.

[0024] Preferably, the temperature for heating and melting is 140-160 DEG C.

[0025] Preferably, the physical foaming includes foaming using air or carbon dioxide or nitrogen; and the chemical foaming includes foaming using a chemical foaming agent, wherein the chemical foaming agent includes one or both of sodium bicarbonate and foaming agent AC; more preferably, the chemical foaming agent is sodium bicarbonate.

[0026] Preferably, the particle size of the iron-based component is ≤ 0.2 mm, more preferably ≤ 0.1 mm.

[0027] Preferably, the pyrite comprises one or both of pyrite or pyrrhotite, and the calcium-magnesium carbonate mineral comprises one or more of limestone, calcite, dolomite or magnesite.

[0028] Preferably, the cooling and forming comprises wet granulation, steel belt granulation or post-solidification breakage granulation.

[0029] A simultaneous denitrification and phosphorus removal lightweight material according to the present application is prepared using the above-mentioned method for preparing a simultaneous denitrification and phosphorus removal lightweight material.

[0030] A method for using a simultaneous denitrification and phosphorus removal lightweight material according to the present application, the above-mentioned simultaneous denitrification and phosphorus removal lightweight material is loaded into a fluidized bed reactor or a fixed bed reactor, inoculation and biofilm formation are performed, and sewage is introduced into the fluidized bed reactor or the fixed bed reactor for denitrification and phosphorus removal treatment.

[0031] 3. Beneficial effects

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] (1) The method for preparing a simultaneous denitrification and phosphorus removal lightweight material according to the present application, by highly fusing sulfur and pyrite, makes the hydrogen ions generated by microorganisms using sulfur for denitrification more easily react with pyrite, promotes the dissolution of pyrite, and improves the overall denitrification rate;

[0034] (2) The method for preparing a simultaneous denitrification and phosphorus removal lightweight material according to the present application, by foaming the molten mixture before cooling and forming the molten mixture, not only improves the denitrification rate of pyrite, but also greatly plays the synergistic effect of sulfur autotrophic denitrification and pyrite autotrophic denitrification, improves the overall denitrification rate, and the generated ferrous ions and iron ions react with phosphate in water to generate insoluble ferrous phosphate and ferric phosphate, achieving good phosphorus removal effect;

[0035] (3) The method for preparing a simultaneous denitrification and phosphorus removal lightweight material according to the present application, by uniformly dispersing bubbles in the molten sulfur, pyrite and calcium-magnesium carbonate molten mixture through physical foaming or chemical foaming, forming a lightweight material, so that the lightweight material has the characteristics of high porosity, large specific surface area, light weight, high reactivity, good microbial adhesion performance, etc.

[0036] (4) The simultaneous denitrification and phosphorus removal lightweight material according to the present application has a density of 0.9-2.5 g / cm 3 , preferably 1.05-1.5 g / cm 3The material is light in weight, and the raw material is easy to obtain and simple to prepare, and is suitable for being used as a filler of fluidized bed, fixed bed and other sewage treatment facilities, and has high and stable treatment efficiency.

[0037] (5) The application method of the simultaneous denitrification and phosphorus removal light material, the simultaneous denitrification and phosphorus removal light material is used as a filler of a fluidized bed or a fixed bed reactor of sewage treatment, nitrogen and phosphorus pollutants in water are deeply removed through the action of microorganisms, the denitration and phosphorus removal effects can reach more than 99% through the fluidized bed reactor treatment, the denitration effect can reach 99% through the fixed bed reactor treatment, and the phosphorus removal effect can reach 91%. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The figure is a denitrification and phosphorus removal effect of the simultaneous denitrification and phosphorus removal light material of the application;

[0039] Figure 2 The figure is a denitrification and phosphorus removal effect of the simultaneous denitrification and phosphorus removal light material of the application;

[0040] Figure 3 The figure is a denitrification effect of the simultaneous denitrification and phosphorus removal light material of the application as a filler of a fluidized bed reactor;

[0041] Figure 4 The figure is a phosphorus removal effect of the simultaneous denitrification and phosphorus removal light material of the application as a filler of a fluidized bed reactor. DETAILED DESCRIPTION

[0042] The application will be further described below in combination with specific embodiments.

[0043] The following detailed description of example embodiments of the application references the accompanying drawings, by which the application in its broader aspect is depicted for illustrative purposes. The application is described more fully below by describing embodiments thereof and specific examples thereof, some of which embodiments and examples can have been simplified or omitted for purposes of clarity where appropriate, but it is understood that since the application can be practiced in a variety of ways, not all of which can be completely described or shown in the accompanying description and drawings, the application should not necessarily be construed as being limited by the specific examples given, and that the application includes all alternatives, modifications, equivalents, and combinations thereof within the scope of the described application. The following detailed description of the application is not intended to limit the scope of the application, but merely to provide a description of the example embodiments of the application, and the description is not intended to limit the scope of the application to the described embodiments, but to illustrate the features and characteristics of the application, to set forth the best mode contemplated for carrying out the application, and to sufficiently enable one skilled in the art to carry out the application. Thus, the scope of the application is to be limited only by the appended claims.

[0044] The preparation method of the synchronous denitrification and dephosphorization light material comprises the following steps: mixing sulfur and a micro-fine iron-based component with a particle size of ≤0.2 mm, more preferably ≤0.1 mm to obtain a mixture, wherein the iron-based component is a mixture of pyrite and calcium-magnesium carbonate or pyrite, the pyrite comprises one or both of pyrite or pyrrhotite, and the calcium-magnesium carbonate comprises one or more of limestone, calcite, dolomite or magnesite; the mass ratio of sulfur to the iron-based component is 6:1-1:2, and the mass ratio of pyrite to calcium-magnesium carbonate in the iron-based component is 1:0-1:4, more preferably the mass ratio of sulfur to the iron-based component is 3:1-1:2, and the mass ratio of pyrite to calcium-magnesium carbonate in the iron-based component is 1:0-1:2. The pyrite in the iron-based component of the embodiment can be pyrite, pyrrhotite and the like.

[0045] The mixture is heated to 140-160°C for high-temperature melting to obtain a molten mixture of sulfur and the iron-based component, and then the molten mixture is cooled and formed to obtain the synchronous denitrification and dephosphorization light material. Alternatively, the molten mixture is subjected to foaming treatment before being cooled and formed, and the molten mixture is continuously stirred during the foaming process, and then the foamed molten mixture is cooled and formed to obtain the synchronous denitrification and dephosphorization light material.

[0046] The cooling and forming method can comprise wet granulation, steel belt granulation or post-solidification crushing granulation. The wet granulation refers to dropping the high-temperature molten mixture into water to form a solid material by cooling; the steel belt granulation refers to dropping the high-temperature molten mixture on a steel belt to form a solid material by cooling; and the post-solidification crushing granulation refers to solidifying the high-temperature molten mixture into a solid material by air cooling.

[0047] It is worth noting that the molten mixture needs to be continuously stirred during the heating and melting of the mixture, and when there is no blocky or granular material in the molten mixture and the color of the molten mixture is uniform and stable, it is considered that a uniform molten mixture is obtained; the uniform molten mixture is subjected to foaming treatment, and the molten mixture needs to be continuously stirred during the foaming treatment to ensure uniform foaming of the molten mixture.

[0048] The foaming treatment can comprise physical foaming or chemical foaming. It is worth noting that the physical foaming method comprises uniformly dispersing air or carbon dioxide or nitrogen in the molten mixture by physical aeration for foaming; the chemical foaming method comprises using a chemical foaming agent for foaming, wherein the chemical foaming agent comprises one or both of sodium bicarbonate and foaming agent AC.

[0049] From the cost, the physical foaming is better than the chemical foaming. The present application is directed to the molten mixture of sulfur and iron-based component, when the mass ratio of sulfur and iron-based component is ≤3, the viscosity of the molten mixture of sulfur and iron-based component is high, the physical foaming or the chemical foaming can be used for foaming, and the physical foaming is preferably used for foaming; and when the mass ratio of sulfur and iron-based component is >3, only the chemical foaming can be used for foaming, and the physical foaming cannot achieve good foaming effect.

[0050] In addition, it is particularly noted that when the physical foaming is used for foaming the molten mixture, the gas is needed to be preheated, and the preheating temperature is ≥50℃. Because the molten mixture is at high temperature of 140-160℃, if the gas is at normal temperature, the local solidification of the molten mixture will occur, thereby affecting the molten state of the molten mixture, and the sufficient and uniform foaming cannot be ensured.

[0051] When the chemical foaming is used for foaming the molten mixture, considering the cost of the chemical foaming agent, the sodium bicarbonate is usually used for foaming. However, because the weight of the sodium bicarbonate is light, the added sodium bicarbonate cannot completely enter the molten mixture, so that the foaming effect cannot be fully played. In order to solve this problem, a small amount of iron-based component (5wt% of the iron-based component from the weighing before the raw material mixing) is mixed with the sodium bicarbonate and then added into the molten mixture, because the weight of the iron-based component is heavy, the sodium bicarbonate can be completely dispersed in the molten mixture together with the iron-based component, so that the sufficient foaming is realized.

[0052] The synchronous denitrification and dephosphorization light material is prepared by the preparation method of the synchronous denitrification and dephosphorization light material. 3 , preferably 1.05-1.5g / cm 3 . The synchronous denitrification and dephosphorization light material has the characteristics of high porosity, large specific surface area, light weight, high reactivity, good microbial adhesion performance, etc., and can be used as the filler of the fluidized bed and fixed bed reactor for sewage treatment, and the nitrogen and phosphorus pollutants in water can be deeply removed by the action of microorganisms.

[0053] The present application highly fuses the sulfur and the pyrite, so that the hydrogen ion produced by the microorganism when the sulfur is used for denitrification can more easily react with the pyrite, and the reaction equation is as follows:

[0054] FeS+H + =Fe 2+ +HS - (4)

[0055] 5Fe 2+ +NO3- +6H + →5Fe 3+ +0.5N2+3H2O (5)

[0056] 5HS - +8NO3 - +3H + →5SO4 2- +4N2+4H2O (6)

[0057] Thus, the dissolution of pyrite is accelerated, the denitrification rate of pyrite is improved, the synergistic effect of sulfur autotrophic denitrification and pyrite autotrophic denitrification is achieved, the overall denitrification rate is improved, and the generated ferrous ions and iron ions react with phosphates in water to generate insoluble ferrous phosphate and iron phosphate, thereby achieving good phosphorus removal effect.

[0058] Before this, the applicant also prepared a denitrification and phosphorus removal lightweight material by using other kinds of iron-containing minerals, which has good denitrification and phosphorus removal effect, but the denitrification rate is relatively poor, which makes the denitrification and phosphorus removal effect unmatched. This problem has been a problem, and then the applicant carried out further research and innovatively proposed to use pyrite as the iron-based component, thereby achieving the synergistic effect of sulfur autotrophic denitrification and pyrite autotrophic denitrification, improving the overall denitrification rate, and especially improving the denitrification rate.

[0059] Example 1

[0060] In this example, sulfur and an iron-based component with a mass ratio of 6:1 are mixed to obtain a mixture, wherein the iron-based component is pyrite. In the specific mixing process, 95% of the pyrite by mass is mixed with all the sulfur to obtain the mixture; the mixture is heated to 140°C for high-temperature melting, and the molten mixture needs to be continuously stirred until no blocky or granular substances exist in the molten mixture, the color of the molten mixture is uniform and stable, and a uniform molten mixture is obtained.

[0061] For this example, the above molten mixture is foamed by a chemical foaming method. The chemical foaming agent added is sodium bicarbonate, and the mass ratio of sulfur, pyrite and sodium bicarbonate is 300:50:2. The remaining 5% of the pyrite is mixed with sodium bicarbonate, and then the mixture of pyrite and sodium bicarbonate is added to the above molten mixture. The molten mixture is continuously mechanically stirred during foaming, the stirring speed is 150-350 rpm, and the stirring time is 20 minutes, so that the gas bubbles are uniformly dispersed in the molten mixture; finally, the synchronous denitrification and phosphorus removal lightweight material is prepared by cooling and shaping. The density of the obtained material is about 2.5 g / cm 3 .

[0062] Example 2

[0063] The basic content of this example is the same as that of Example 1, except that the mass ratio of sulfur to the iron-based component in this example is 1:2, wherein the iron-based component is pyrite. The sulfur and the pyrite are mixed to obtain a mixture, and the mixture is heated to 140°C to perform high-temperature melting, thereby obtaining a molten mixture.

[0064] For this example, the molten mixture obtained has a high viscosity, and the molten mixture is foamed by physical foaming. The molten mixture is foamed by blowing nitrogen into the molten mixture under physical aeration, wherein the nitrogen flow rate is 80 mL / min, and the blowing time is 15 minutes. The molten mixture is continuously mechanically stirred at a stirring speed of 500-600 rpm during the foaming process, and the stirring time is 60 minutes, so that the gas bubbles are uniformly dispersed in the molten mixture. The stirring time is the foaming time. Finally, the molten mixture is cooled and shaped to obtain a simultaneous denitrification and phosphorus removal lightweight material. The density of the obtained material is about 1.05 g / cm 3 .

[0065] Example 3

[0066] The basic content of this example is the same as that of Example 1, except that the mass ratio of sulfur to the iron-based component in this example is 1:1, wherein the iron-based component is pyrite and calcium-magnesium carbonate, and the mass ratio of the pyrite to the calcium-magnesium carbonate is 1:2. The sulfur, the pyrite, and the calcium-magnesium carbonate are mixed to obtain a mixture, and the mixture is heated to 160°C to perform high-temperature melting, thereby obtaining a molten mixture.

[0067] The molten mixture is chemically foamed by adding a chemical foaming agent sodium bicarbonate. The mass ratio of the sulfur, the pyrite, and the calcium-magnesium carbonate, and the foaming agent is 300:300:5. The molten mixture is continuously magnetically stirred at a stirring speed of 50-100 rpm during the foaming process, and the stirring time is 5 minutes, so that the gas bubbles are uniformly dispersed in the molten mixture. Finally, the molten mixture is cooled and shaped to obtain a simultaneous denitrification and phosphorus removal lightweight material. The density of the obtained material is about 0.9 g / cm 3 .

[0068] Example 4

[0069] The basic content of this example is the same as that of Example 1, except that the mass ratio of sulfur to the iron-based component in this example is 1:2, wherein the iron-based component is pyrite and calcium-magnesium carbonate, and the mass ratio of the pyrite to the calcium-magnesium carbonate is 1:2. The sulfur, the pyrite, and the calcium-magnesium carbonate are mixed to obtain a mixture, and the mixture is heated to 160°C to perform high-temperature melting, thereby obtaining a molten mixture.

[0070] The above molten mixture was chemically foamed by adding sodium bicarbonate as a foaming agent. The mass ratio of sulfur, pyrite, calcium magnesium carbonate, and foaming agent was 300:600:10. During the foaming process, the molten mixture was continuously mechanically stirred at a speed of 150-250 rpm for 30 minutes to ensure that the bubbles were uniformly dispersed in the molten mixture. Finally, the mixture was cooled and molded to obtain a lightweight material with simultaneous nitrogen and phosphorus removal. The density of the obtained material was measured to be approximately 1.23 g / cm³. 3 .

[0071] Example 5

[0072] Weigh 10g of the material prepared in Example 3 and set aside. Simultaneously add 50mL of a solution containing 30mg / L NO3 to the batch tube reaction vessel. - -N, 15 mg / L PO4 3- Wastewater containing -P and 10g of this lightweight material were added to a reaction vessel along with 3.5mL of a 10% sulfur-autotrophic denitrifying bacteria solution (the solution volume was 7% of the wastewater volume). The mixture was then purged with nitrogen to remove oxygen, and the vessel was sealed for denitrification. After 10 days of incubation, NO3- in the reactor was analyzed on days 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. - -N,PO4 3- -P concentration was measured, and nitrogen and phosphorus were basically completely removed from the reactor in about 3 days. Specific nitrogen and phosphorus removal data are as follows: Figure 1 As shown.

[0073] Example 6

[0074] The basic content of this embodiment is the same as that of Embodiment 1, except that: in this embodiment, sulfur and iron-based components are mixed in a mass ratio of 1:1 to obtain a mixture, wherein the iron-based components are pyrite and calcium magnesium carbonate, and the mass ratio of pyrite to calcium magnesium carbonate is 3:1. The mixture of sulfur, pyrite, and calcium magnesium carbonate is heated to 150°C for high-temperature melting to obtain a molten mixture.

[0075] The above molten mixture was chemically foamed by adding sodium bicarbonate as a foaming agent. The mass ratio of sulfur, pyrite, calcium magnesium carbonate, and foaming agent was 300:300:5. During the foaming process, the molten mixture was continuously mechanically stirred at a speed of 220-260 rpm for 30 minutes to ensure uniform bubble dispersion. Finally, the mixture was cooled and molded to obtain a lightweight material with simultaneous denitrification and phosphorus removal (such as...). Figure 2 (As shown). The density of the obtained material was measured to be approximately 1.06 g / cm³. 3 The porosity is 52.7%.

[0076] The above material is crushed, and the material with an average particle size of 2.6 mm is screened out as a filler, which is loaded into a fluidized bed reactor, inoculated with anaerobic sludge and added with a culture solution, and after 7 days of cultivation, biofilm formation is completed. During the process of running for 100 days under constant temperature of 28℃ and light avoidance, the average nitrate nitrogen of the influent is 31.9 mg / L, the average nitrate nitrogen of the effluent is 0.03 mg / L, the average phosphate phosphorus of the influent is 1.98 mg / L, and the average phosphate phosphorus of the effluent is 0.01 mg / L. The specific nitrogen and phosphorus removal effect is shown in Table 1. Figure 3 and Figure 4 .

[0077] Example 7

[0078] The basic content of the present example is the same as that of Example 1, except that in the present example, sulfur and an iron-based component with a mass ratio of 4:3 are mixed to obtain a mixture, wherein the iron-based component is pyrite and calcium-magnesium carbonate, and the mass ratio of pyrite to calcium-magnesium carbonate is 2:1. The sulfur, pyrite and calcium-magnesium carbonate are mixed to obtain a mixture, and the mixture is heated to 150℃ for high-temperature melting to obtain a uniform molten mixture. Finally, the molten mixture is cooled and shaped to prepare a simultaneous nitrogen and phosphorus removal light material. The density of the obtained material is about 2.91 g / cm 3 .

[0079] The above material is crushed, and the material with an average particle size of 2.6 mm is screened out as a filler, which is loaded into a fixed bed reactor, inoculated with anaerobic sludge and added with a culture solution, and after 7 days of cultivation, biofilm formation is completed. During the process of running for 100 days under constant temperature of 28℃ and light avoidance, the average nitrate nitrogen of the influent is 31.9 mg / L, the average nitrate nitrogen of the effluent is 0.03 mg / L, the average phosphate phosphorus of the influent is 1.98 mg / L, and the average phosphate phosphorus of the effluent is 0.01 mg / L. The specific nitrogen and phosphorus removal effect is shown in Table 1.

[0080] The simultaneous nitrogen and phosphorus removal light material of the present application is used as a microbial carrier in a fixed bed or fluidized bed reactor for biochemical treatment of sewage, and the microorganisms simultaneously utilize the loaded light material as an electron donor for denitrification, and the metabolic products of the microorganisms, iron ions, and calcium and magnesium ions simultaneously precipitate and remove phosphorus, so that high-efficiency simultaneous nitrogen and phosphorus removal is achieved.

Claims

1. A method for preparing lightweight materials with simultaneous nitrogen and phosphorus removal, characterized in that: Sulfur and iron-based components are mixed to obtain a mixture, wherein the iron-based component is a mixture of pyrite and calcium magnesium carbonate or pyrite; the mixture is heated and melted to 140℃~160℃ to obtain a molten mixture; and then the molten mixture is cooled and shaped to obtain a lightweight material with simultaneous denitrification and dephosphorization. The mass ratio of sulfur to iron-based components is 6:1 to 1:2, and the mass ratio of pyrite to calcium magnesium carbonate in the iron-based components is 1:0 to 1:

4. Before the molten mixture is cooled and molded, the molten mixture is foamed and continuously stirred during the foaming process. Then the foamed molten mixture is cooled and molded to obtain a lightweight material with simultaneous denitrification and dephosphorization. Foaming treatment includes physical foaming or chemical foaming; when the mass ratio of sulfur to iron-based components is ≤3, physical foaming or chemical foaming is used; when the mass ratio of sulfur to iron-based components is >3, only chemical foaming can be used. The physical foaming method includes using air, carbon dioxide, or nitrogen for foaming; the chemical foaming method includes using a chemical foaming agent, wherein the chemical foaming agent includes one or two of sodium bicarbonate and foaming agent AC.

2. The method for preparing a lightweight material with simultaneous nitrogen and phosphorus removal according to claim 1, characterized in that: The particle size of the iron-based component is ≤0.2mm.

3. A lightweight material for simultaneous nitrogen and phosphorus removal, characterized in that, The material was prepared using the method described in any one of claims 1 to 2 for the preparation of a lightweight material with simultaneous nitrogen and phosphorus removal.

4. A method for applying a lightweight material that simultaneously removes nitrogen and phosphorus, characterized in that: The lightweight material for simultaneous nitrogen and phosphorus removal described in claim 3 is loaded into a fluidized bed reactor or a fixed bed reactor for inoculation and biofilm formation. Wastewater is then introduced into the fluidized bed reactor or the fixed bed reactor for nitrogen and phosphorus removal treatment.

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