Preparation method and application of quick biofilm formation sulfur autotrophic denitrification filler

Abstract

The application provides a preparation method and application of a quick-membrane-attached sulfur autotrophic denitrification filler, and the specific steps of the preparation method are as follows: S1, mixing pyrite tailings slag, sulfur, calcium carbonate and sodium bicarbonate; S2, heating and rotating the material obtained in S1 in a rotary reaction kettle until the sulfur component is completely melted, stopping heating after the material is uniformly mixed, cooling, and continuously rotating the reaction kettle for granulation during the cooling process; S3, stopping the rotation of the reaction kettle in S2 when the material forming rate is more than 70%, and screening the material, so that the quick-membrane-attached sulfur autotrophic denitrification filler is obtained. The filler has a large specific surface area and high porosity, is beneficial to quick membrane-attachment, and can be successfully applied to wetland treatment.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to a method for preparing and applying a rapid biofilm-attached sulfur autotrophic denitrification packing material. Background Technology

[0002] Sulfate autotrophic denitrification is a novel wastewater treatment process. It mainly uses sulfur autotrophic denitrifying microorganisms to convert nitrates in water into sulfates. The oxygen atoms of nitrates are transferred to sulfates, and the nitrate content is reduced, thereby achieving the purpose of purifying water.

[0003] The existing sulfur autotrophic denitrification process has several problems and drawbacks, including slow microbial growth, slow biofilm formation on the packing material, and a long start-up period. Furthermore, sulfur autotrophic denitrification technology is currently mainly used in deep nitrogen removal processes at wastewater treatment plants, and rarely applied to wetland purification. The application of sulfur autotrophic denitrification technology in wetlands mainly faces challenges such as packing material clogging, lack of outlet for backwash effluent, and large fluctuations in wetland water quality. Summary of the Invention

[0004] This invention provides a method for preparing and applying a rapid biofilm-forming sulfur autotrophic denitrification packing material. The packing material has a large specific surface area, which is beneficial for achieving rapid biofilm formation; and it can be successfully applied to wetland treatment.

[0005] The technical solution of this invention is a method for preparing a rapid biofilm-attached sulfur autotrophic denitrification packing, comprising the following steps:

[0006] S1. Mix pyrite tailings slag, sulfur, calcium carbonate, and sodium bicarbonate.

[0007] The materials obtained from S2 and S1 are transferred into a rotary reactor for heating and rotation until the sulfur components are completely melted. After the materials are mixed evenly, heating is stopped and the mixture is cooled. During the cooling process, the reactor continues to rotate for granulation.

[0008] In reactions S3 and S2, the rotary granulation process in the reactor is stopped when the material forming rate is above 70%. The material is then screened to obtain the rapid biofilm-attached sulfur autotrophic denitrification packing.

[0009] Furthermore, the mass ratio of pyrite tailings slag, sulfur, calcium carbonate, and sodium bicarbonate in S1 is 10–100: 50–250: 2–50: 1–10.

[0010] Furthermore, in S2, the reactor temperature is 105-120℃ and the rotation speed is 60-90 r / min.

[0011] Furthermore, a scraper is installed inside the reactor, and the direction of rotation of the scraper is opposite to the direction of rotation of the reactor; the rotation speed of the scraper is 300-600 r / min.

[0012] Furthermore, during cooling in S2, the temperature is reduced to below 80°C.

[0013] Furthermore, particles larger than 2mm in size during sieving in S3 are considered finished filler, while particles smaller than 2mm are returned to the S2 rotary reactor for rotary granulation.

[0014] This invention also relates to the application of the aforementioned rapid biofilm-attached sulfur autotrophic denitrification packing material in wetland purification.

[0015] Furthermore, the specific wetland sulfur autotrophic denitrification application device includes a first coarse gravel layer, a fine gravel layer, a rapid biofilm-forming sulfur autotrophic denitrification packing layer, and a second coarse gravel layer arranged sequentially along the water flow direction. Each layer is vertically arranged and has the same height. Each layer is covered with a nutrient soil layer. The first coarse gravel layer has an inlet at one end, and the second coarse gravel layer has an outlet at one end. The device also includes a sodium thiosulfate feeding pipe connected to the inlet.

[0016] Furthermore, the concentration of sodium thiosulfate, the liquid sulfur source in the wetland system, is 5-15 mg / L.

[0017] Furthermore, a water distributor is provided at the inlet of the first coarse gravel layer, and the water distributors are evenly distributed from top to bottom; the thickness ratio of the first coarse gravel layer, the fine gravel layer, the rapid biofilm-attached sulfur autotrophic denitrification packing layer, and the second coarse gravel layer is 2-3:1.5-2:3-4:1-2.

[0018] The present invention has the following beneficial effects:

[0019] 1. In the preparation of the packing material, this invention applies the principle of countercurrent three-dimensional motion, employing a combination of rotary granulation and high-speed granulation with a scraper rotating in the opposite direction to prepare a sulfur autotrophic denitrification packing material with higher roughness. Before and after treatment using the packing material preparation process of this invention, the BET specific surface area of ​​the packing material can reach 1.5336 m². 2 With a specific surface area of ​​over / g, the filler material's specific surface area is significantly increased, which is beneficial for achieving rapid biofilm formation.

[0020] 2. In the filler preparation process, the present invention can improve the porosity of the product by heating and melting sulfur, utilizing high-speed rotation and rapid phase change. Higher porosity and larger pore size are conducive to rapid mass transfer between the matrix and metabolites, and accelerate the metabolism of microorganisms.

[0021] 3. This invention applies sulfur autotrophic denitrification technology to wetland systems, which can overcome the technical problem of packing blockage. At the same time, the wetland provides solid-phase sulfur electron donors through the packing and liquid-phase sulfur electron donors through the addition of liquid-phase sodium thiosulfate solution. The synergistic homologous and heterogeneous electron donors ensure the timely supply of electron donors under unsteady conditions and the denitrification effect of the wetland system.

[0022] 4. In wetland systems, the clogging of the packing material is a critical concern. This invention incorporates gravel of varying gradations at the inlet, enabling the removal of suspended solids from the water before it enters the autotrophic denitrification layer, effectively reducing packing material clogging. Simultaneously, the inlet and outlet design allows for backwashing after a period of use, with the backwash water exiting through the inlet, providing an outlet and further preventing packing material clogging. Furthermore, each gravel layer and packing material layer utilizes an independent frame structure for easy disassembly and assembly, facilitating timely removal, thorough flushing, and replacement of the packing material. Finally, the backwash sludge from this wetland device can be returned to the nutrient soil layer to replenish the nutrients needed for plant growth, achieving resource utilization of wastewater and sludge. Attached Figure Description

[0023] Figure 1 The rapid biofilm-attached sulfur autotrophic denitrification packing material prepared in Example 1 is used.

[0024] Figure 2 This is a microstructure diagram of the packing material obtained in Example 1.

[0025] Figure 3 The BET test curve is shown for the packing material obtained in Example 1.

[0026] Figure 4 The sulfur autotrophic denitrification packing obtained in Comparative Example 1 is used.

[0027] Figure 5 The BET test curve is shown for the packing material obtained in Comparative Example 1.

[0028] Figure 6 This is a schematic diagram of a wetland sulfur autotrophic denitrification application device. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0030] Example 1

[0031] Preparation of rapid biofilm-attached sulfur autotrophic denitrification packing material

[0032] S1. Mix pyrite tailings slag, sulfur, calcium carbonate, and sodium bicarbonate in a mass ratio of 100:200:30:5.

[0033] The materials obtained from S2 and S1 are transferred into a rotary reactor for heating and rotation at a speed of 90 r / min. The reactor is equipped with a scraper that rotates in the opposite direction at a speed of 300 r / min. The reactor is heated to 105-110℃ until the sulfur components are completely melted. After the materials are mixed evenly, heating is stopped, and the mixture is cooled to 80℃. During the cooling process, the reactor continues to rotate for granulation.

[0034] In reactors S3 and S2, granulation is stopped when the material forming rate reaches over 70%. The material is then screened. Particles with a diameter of 2mm or larger can be used as fillers for rapid biofilm formation and autotrophic denitrification. Particles with a diameter less than 2mm are returned to the S2 rotary reactor for further granulation.

[0035] The obtained packing material photos are as follows Figure 1 As shown, its microstructure is shown in [image missing]. Figure 2 The BET test curve of the packing material is as follows: Figure 3 As shown, the specific surface area is 1.5336 m². 2 / g; Denitrification (as NO3) - The rate (based on -N) was 6.4 mg / Lh. -1 .

[0036] Example 2

[0037] Based on Example 1, the difference is that the scraper rotates at a speed of 450 r / min.

[0038] Example 3

[0039] Based on Example 1, the difference is that the scraper rotates at a speed of 600 r / min.

[0040] Example 4

[0041] The only difference between this embodiment and Embodiment 1 is that in S1, the pyrite tailings slag, sulfur, calcium carbonate, and sodium bicarbonate are in a mass ratio of 100:300:100:20, while all other conditions are the same as in Embodiment 1.

[0042] Example 5

[0043] The only difference between this embodiment and Embodiment 1 is that the slag, sulfur, calcium carbonate, and sodium bicarbonate in step (I) are in a mass ratio of 60:100:30:5, while all other conditions are the same as in Embodiment 1.

[0044] The denitrification (in NO3) of the packing material obtained in the above examples - -N (measured) rate, see Table 1 below.

[0045] Table 1

[0046] <![CDATA[Denitrification rate (mg / L·h -1 )]]> 6.4 6.7 6.2 6.1 6.4

[0047] Comparative Example 1

[0048] S1. Mix pyrite tailings slag, sulfur, calcium carbonate, and sodium bicarbonate in a mass ratio of 100:200:30:5.

[0049] The materials obtained from S2 and S1 are heated in an oil bath to 105-110℃, and heating is stopped after the materials are in a molten state.

[0050] The molten materials in S3 and S2 were passed through a 2cm porous sieve and dripped into a 2% (w / w) calcium chloride solution, then refrigerated and solidified for 24 hours to obtain the following result: Figure 4 The sulfur autotrophic denitrification packing shown has a smooth surface.

[0051] Comparative Example 2

[0052] Compared to Example 1, the difference lies in that the scraper is not rotated in the same direction inside the reactor; all other conditions are the same as in Example 1. The BET detection curve of the obtained packing is shown below. Figure 5 As shown, the specific surface area of ​​the packing is 0.3058 m². 2 / g.

[0053] Comparative Example 3

[0054] Compared with Example 1, the difference is that in S1, the slag, sulfur, calcium carbonate, and sodium bicarbonate are in a mass ratio of 300:200:30:5, while all other conditions are the same as in Example 1.

[0055] Comparative Example 4

[0056] Compared with Example 1, the difference is that sodium bicarbonate is not added in S1, while all other conditions are the same as in Example 1.

[0057] Comparative Example 5

[0058] Compared with Example 1, the difference is that no pyrite tailings slag is added in S1, while all other conditions are the same as in Example 1.

[0059] Table 2

[0060] <![CDATA[Denitrification rate (mg / L·h -1 )]]> 2.6 4.7 3.4 5.5 4.3

[0061] Application Case 1

[0062] The packing material from Example 1 is used for wetland purification, and the application device (such as...) Figure 6The filter media consists of a first coarse gravel layer 1, a fine gravel layer 2, a sulfur autotrophic denitrification packing layer 3, and a second coarse gravel layer 4, arranged sequentially along the water flow direction. Each layer is vertically arranged and of the same height. A nutrient soil layer 5 is laid on top of each layer. An inlet 6 is located at the end of the first coarse gravel layer, and an outlet 7 is located at the end of the second coarse gravel layer. The inlet and outlet can be reversed later to serve as backwashing channels for periodic backwashing to prevent clogging. A water distributor is also installed at the inlet 6 of the first coarse gravel layer 1, evenly distributed from top to bottom to ensure uniform water distribution. The gravel particle size in the first and second coarse gravel layers 1 and 4 is 5-8 cm; the gravel particle size in the fine gravel layer 2 is 3-5 cm. Multi-graded filter media is used to reduce clogging of the sulfur autotrophic denitrification packing. The thickness ratio of the first coarse gravel layer 1, the fine gravel layer 2, the sulfur autotrophic denitrification packing layer 3, and the second coarse gravel layer 4 is 1-2:1.5-2:3-4:1-2, and in this case, it is preferably 2:1.5:3:1.

[0063] The first coarse gravel layer 1, the fine gravel layer 2, the sulfur autotrophic denitrification packing layer 3, and the second coarse gravel layer 4 are all independently set up with a frame structure. The frames are filled with coarse gravel, fine gravel, or sulfur autotrophic denitrification packing. This facilitates the cleaning and replacement of the packing. The device also includes a pH buffer solution and a sulfur source storage tank, which are connected to the inlet via pipes and valves, enabling rapid supply of electron donors under unsteady-state conditions.

[0064] In the specific treatment process, the wetland water to be treated enters the device through the inlet, passes through the first coarse gravel layer 1 and the fine gravel layer 2 to remove suspended solids, and then enters the sulfur autotrophic denitrification packing layer 3. Denitrification occurs in this layer, purifying the water. The purified water then passes through the second coarse gravel layer and the outlet. After a period of operation, clean water is introduced through the outlet for backwashing. Impurities in the packing layer are discharged through the inlet in the reverse direction. The backwash water can be reused in the upper layer of the device, and the solid phase is reused as a nutrient soil layer. To ensure the temperature operation of the device, a dosing pipe is also installed at the inlet. Depending on the water quality, a pH buffer solution (such as a saturated NaHCO3 solution) and a liquid high-efficiency sulfur source (such as sodium thiosulfate solution, with a controlled concentration of 5-15 mg / L) are added to ensure the stability of the wetland system's pH and the effluent quality.

[0065] After the device is operating stably, it can achieve an average total nitrogen level of 7.23 mg / L in the influent, an average total nitrogen level of 3.41 mg / L in the effluent, and an average nitrogen removal rate of 6.4 mg / L / h. -1 When the packing material was replaced with that in Comparative Example 5, the total nitrogen in the influent was 7.23 mg / L, the average total nitrogen in the effluent was 4.66 mg / L, and the average denitrification rate was 4.3 mg / L / h. -1 The filler treatment in Example 1 showed better results.

[0066] Application Case 2

[0067] The difference between Application Case 2 and Application Case 1 is that no liquid sulfur source replenishment system is set up, making it impossible to replenish the liquid sulfur source in a timely manner through the control system. The start-up time of the wetland device is 1.7 times that of Application Case 1, and the average denitrification rate is 1.6 mg / Lh lower than that of Application Case 1. -1 .

[0068] The above embodiments are only for illustrating the technical concept and features of the present invention, and the content described is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Within the technical scope disclosed in the present invention, equivalent changes or improvements made to the technical solution and inventive concept of the present invention should all be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a rapid biofilm-attached sulfur autotrophic denitrification packing, characterized in that, Includes the following steps: S1. Mix pyrite tailings slag, sulfur, calcium carbonate, and sodium bicarbonate in a mass ratio of 10~100:50~250:2~50:1~10; The materials obtained from S2 and S1 are transferred into a rotary reactor for heating and rotation. The reactor temperature is 105-120℃, and the rotation speed is 60-90 r / min, until the sulfur component is completely melted. After the materials are mixed evenly, heating is stopped, and cooling is carried out. During the cooling process, the reactor continues to rotate for granulation. A scraper is installed inside the reactor, and the rotation direction of the scraper is opposite to that of the reactor. The rotation speed of the scraper is 300-600 r / min. In reactions S3 and S2, the rotary granulation process in the reactor is stopped when the material forming rate is above 70%. The material is then screened to obtain the rapid biofilm-attached sulfur autotrophic denitrification packing.

2. The preparation method according to claim 1, characterized in that: In S2, the temperature is cooled to below 80°C.

3. The preparation method according to claim 1, characterized in that: In S3, particles larger than 2mm are considered finished filler material during sieving, while particles smaller than 2mm are returned to the S2 rotary reactor for rotary granulation.

4. The application of the rapid biofilm-attached sulfur autotrophic denitrification packing material obtained by the preparation method according to any one of claims 1 to 3 in wetland purification.

5. The application according to claim 4, characterized in that: The specific wetland sulfur autotrophic denitrification application device includes a first coarse gravel layer (1), a fine gravel layer (2), a rapid biofilm-attached sulfur autotrophic denitrification packing layer (3), and a second coarse gravel layer (4) arranged sequentially along the water flow direction. Each layer is vertically arranged and has the same height. Each layer is covered with a nutrient soil layer (5). The first coarse gravel layer has an inlet (6) at one end, and the second coarse gravel layer has an outlet (7) at one end. The device also includes a sodium thiosulfate feeding pipe connected to the inlet.

6. The application according to claim 5, characterized in that: The concentration of sodium thiosulfate in the liquid sulfur source in the wetland system is 5-15 mg / L.

7. The application according to claim 5, characterized in that: The inlet (6) of the first coarse gravel layer (1) is also equipped with a water distributor, which is evenly distributed from top to bottom; the thickness ratio of the first coarse gravel layer (1), the fine gravel layer (2), the rapid biofilm sulfur autotrophic denitrification packing layer (3) and the second coarse gravel layer (4) is 2~3:1.5~2:3~4:1~2.

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