A sulfur autotrophic denitrification mixed-state moving bed and sulfur autotrophic denitrification method

Abstract

This invention discloses a sulfur autotrophic denitrification mixed-state moving bed, comprising a mixed-state moving bed body, a cylinder, a support, a water distribution device, an air-lift system, a fiber filter layer, an inlet pipe, and an outlet pipe. The cylinder, support, air-lift system, and water distribution device are all located within the mixed-state moving bed body. The cylinder is mounted on the support. The air-lift system includes an air inlet pipe, an air-lift pipe, and a pressure-relief cone plate. The air-lift pipe is vertically positioned at the center of the cylinder and has an inlet end and an outlet end. The air inlet pipe extends into the inlet end. The pressure-relief cone plate is sleeved on the outside of the air-lift pipe and located above the inlet end. The water distribution device is sleeved on the outside of the air-lift pipe and located above the pressure-relief cone plate. The fiber filter layer is sleeved on the outside of the cylinder and located above the support, filling the space between the cylinder and the mixed-state moving bed body. Sulfur autotrophic granular filter media is placed within the cylinder and the mixed-state moving bed body. The air-lift pipe, pressure-relief cone plate, and water distribution device are surrounded by the sulfur autotrophic granular filter media. The inlet pipe is connected to the water distribution device, and the outlet pipe is located at the top side of the mixed-state moving bed body.

Description

Technical Field

[0001] This invention relates to the field of biological denitrification technology for wastewater, and in particular to a sulfur autotrophic denitrification mixed moving bed and a sulfur autotrophic denitrification method. Background Technology

[0002] Sulfur autotrophic denitrification refers to the process of denitrifying nitrogen using autotrophic bacteria as electron donors, such as sulfur or pyrite powder. In recent years, the application of sulfur autotrophic nitrogen removal technology has begun to emerge in China, with the main process mode employing a filter bed. Sulfur, pyrite powder, limestone, and other powders are mixed and sintered into stable, hard particles. These particles are then placed in a filter bed as packing material, and the water to be treated flows through the filter media in an upward or downward flow to react. Sulfur autotrophic microorganisms grow on the surface of the filter media particles, existing in the form of a biofilm, similar to a conventional biological filter (BAF).

[0003] However, the main problem with the existing biofilter model of sulfur autotrophic denitrification process is low efficiency, mainly due to the following issues: (1) Mass transfer efficiency problem. The material (sulfur powder) exists in the form of coarse particles (mostly between 4-12 mm in diameter), and only the material on the surface of the particles can participate in the reaction. Obviously, the specific surface area of ​​coarse particles is limited, much smaller than that of particulate matter. The limited specific surface area of ​​the material in contact with water is the main reason for the low reaction efficiency; (2) The autotrophic microorganisms participating in the reaction grow on the surface of the packing particles and exist in the form of biofilm. This results in the biofilm occupying the surface of the packing particles, which blocks the contact between water and material, further reducing the specific surface area of ​​the reaction. It is contradictory to both maximize the surface area of ​​the packing and water in contact and to increase the total biomass by growing more biofilm on the surface of the packing; (3) It cannot be guaranteed that the water flow can flow uniformly through the filter bed. Due to various reasons such as water distribution and local blockage, the hydraulic uniformity will be affected, and the packing material in each area will not be in a consistently efficient state, resulting in a decrease in overall efficiency; (4) The effect of uneven pH value: along the water flow direction, there is a gradient in pH distribution. The pH range suitable for reaction is limited, resulting in a decrease in overall treatment efficiency. Therefore, it is urgent to develop a sulfur autotrophic denitrification mixed moving bed and a sulfur autotrophic denitrification method to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a sulfur autotrophic denitrification mixed moving bed and a sulfur autotrophic denitrification method.

[0005] According to one aspect of the present invention, a sulfur autotrophic denitrification mixed-state moving bed is provided, comprising a mixed-state moving bed body, a cylinder, a support, a water distribution device, an air-lift system, a fiber filter layer, an inlet pipe, and an outlet pipe. The cylinder, support, air-lift system, and water distribution device are all located within the mixed-state moving bed body. The support is detachably mounted within the mixed-state moving bed body, and the cylinder is detachably mounted on the support. The air-lift system includes an inlet pipe, an air-lift pipe, and a pressure-relief frustum plate. The air-lift pipe is vertically positioned at the center of the cylinder and has an inlet end and an outlet end. The inlet pipe passes through the side wall of the mixed-state moving bed body. The pressure relief cone plate is fitted on the outside of the air lift pipe and located above the inlet end. The water distribution device is located in the middle of the mixed moving bed, fitted on the outside of the air lift pipe and above the pressure relief cone plate. The fiber filter layer is fitted on the outside of the cylinder, located above the support, and fills the space between the cylinder and the mixed moving bed. The cylinder and the mixed moving bed contain sulfur autotrophic denitrification granular filter media. The air lift pipe, pressure relief cone plate, and water distribution device are surrounded by sulfur autotrophic denitrification granular filter media. The water inlet pipe is connected to the water distribution device, and the water outlet pipe is located at the top of the side of the mixed moving bed.

[0006] In some embodiments, the present invention further includes a metal mesh and an air-lift reflux circulation pipe. The metal mesh is sleeved on the outside of the cylinder, located below the fiber filter layer and above the support, with its outer periphery abutting against the side wall of the mixed moving bed. One end of the air-lift reflux circulation pipe extends below the pressure relief cone plate, and the other end passes through the side wall of the mixed moving bed, extends into the cylinder, and is located between the outlet end and the sulfur autotrophic denitrification granular filter media.

[0007] In some embodiments, the mixed moving bed body is provided with a clear water zone and a buffer zone. The clear water zone is located above the fiber filter layer, and the outlet pipe is located above the fiber filter layer and connected to the clear water zone. The buffer zone is located below the metal mesh and above the sulfur autotrophic denitrification granular filter media.

[0008] In some embodiments, the water distribution device is provided with a water distribution port, the fiber filter layer is filled by stacking and wrapping biological rope packing, the thickness is 20-30cm, the metal mesh has a pore size of 5x5-10x10mm and a wire diameter of 1mm, the apex angle of the pressure relief cone plate is 45-55°, and the distance between the top of the pressure relief cone plate and the inlet end is one-sixth to one-quarter of the length of the air lift pipe.

[0009] In some embodiments, the present invention further includes a sedimentation and sludge discharge device, which includes a radial flow sedimentation tank, an inlet central cylinder, a sludge discharge pipe, a sludge discharge valve, a second valve, and a third valve. The air lift reflux circulation pipe is provided with a first valve front pipe, a first valve, and a first valve rear pipe connected in sequence. The inlet central cylinder is installed at the top center of the radial flow sedimentation tank. One end of the second valve is connected to the first valve front pipe, and the other end is connected to the inlet central cylinder. One end of the third valve is connected to the first valve rear pipe, and the other end is connected to the radial flow sedimentation tank. The third valve is located below the second valve. One end of the sludge discharge valve is connected to the bottom of the radial flow sedimentation tank, and the other end is connected to the sludge discharge pipe.

[0010] According to another aspect of the present invention, a method for sulfur autotrophic denitrification using a mixed-state moving bed is provided, characterized by comprising the following steps:

[0011] Step a: Add sulfur autotrophic denitrification granular filter media and powder, and prevent the sulfur autotrophic denitrification granular filter media from entering the air lift pipe. The mass of the powder is 10% to 50% of the weight of the sulfur autotrophic denitrification granular filter media.

[0012] Step b: Nitrate nitrogen wastewater is introduced into the water distribution device, forming water flows in both upward and downward directions. The water enters the mixed moving bed, where the powder material forms a slurry upon contact with the nitrate nitrogen wastewater. The pores between the sulfur autotrophic denitrification granular filter media are filled with the slurry, microbubbles, water, and sulfur autotrophic microorganisms, forming a mixed filter bed composed of sulfur autotrophic denitrification granular filter media, slurry, and sulfur autotrophic microorganisms. The nitrate nitrogen content in the nitrate nitrogen wastewater is 50–300 mg / L, and the pH value is 8.5–11.

[0013] Step c: Compressed air is introduced into the air lift pipe to circulate the sulfur autotrophic denitrification granular filter media, slurry, and sulfur autotrophic microorganisms from the bottom to the top and back to the bottom of the mixed-state filter bed, thereby treating the nitrate nitrogen wastewater with sulfur autotrophic mixed-state denitrification.

[0014] Step d: Open the first valve and close the second and third valves. The liquid at the top of the cylinder is transported to the bottom of the mixed filter bed through the air lift reflux circulation pipe for reflux and is then drawn back into the air lift pipe for circulation.

[0015] In some embodiments, the method of the present invention further includes step e: when the inlet water pressure is greater than 50 kPa, the first valve is closed, the second valve and the third valve are opened to perform sludge discharge treatment, and after the sludge discharge treatment is completed, the first valve is opened, the second valve and the third valve are closed to perform reset.

[0016] In some embodiments, the particle size of the sulfur autotrophic denitrification granular filter media is 3–6 mm.

[0017] In some embodiments, the powder comprises sulfur powder and limestone powder, with a mass ratio of sulfur powder to limestone powder of 7:3.

[0018] In some embodiments, the sulfur powder has a particle size of 20 μm to 200 μm, and the limestone powder has a particle size of 20 μm to 200 μm.

[0019] The beneficial effects of the present invention are: (1) The sulfur autotrophic denitrification mixed moving bed of the present invention has a unique structural design. The volumetric load calculated based on the stacked volume of the sulfur autotrophic denitrification granular filter media is 0.8-1.2 kg.N / m3.d, which means that the denitrification efficiency is 2.5-4 times higher than that of ordinary sulfur autotrophic denitrification filter.

[0020] (2) The sulfur autotrophic denitrification mixed moving bed of the present invention can operate continuously for 24 hours. Through the air lifting system and water distribution device, the sulfur autotrophic denitrification granular filter media can be continuously moved up and down in a circulating manner, thereby realizing the renewal of the surface of the granular filter media. There is no need to stop the machine for backwashing, nor is there a need to configure a special filter backwashing system, and there is no need to consider the disposal of a large amount of backwash water.

[0021] (3) The sulfur autotrophic denitrification mixed moving bed of the present invention solves the sludge discharge problem of ordinary sulfur autotrophic denitrification filter by setting up a radial flow sedimentation tank;

[0022] (4) The sulfur autotrophic denitrification mixed moving bed of the present invention does not have the problem of local filter material blockage, does not require regular shutdown for manual cleaning, and has low equipment operation and maintenance costs. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a sulfur autotrophic denitrification mixed moving bed according to the present invention.

[0024] Figure 2 This is a structural diagram illustrating the specific application of a sulfur autotrophic denitrification mixed moving bed according to Embodiment 2 of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments.

[0026] Example 1

[0027] refer to Figure 1 This invention provides a sulfur autotrophic denitrification mixed-state moving bed, comprising a mixed-state moving bed body 1, a cylinder 2, a support 3, a water distribution device 4, an air-lift system, a fiber filter layer 6, a metal mesh 7, an air-lift reflux circulation pipe 8, an inlet pipe 9, an outlet pipe 10, and a sedimentation and sludge removal device 11. The cylinder 2, support 3, air-lift system, water distribution device 4, fiber filter layer 6, and metal mesh 7 are all located within the mixed-state moving bed body 1.

[0028] The support frame 3 has a circular ring and multiple support plates 31, which are symmetrically installed in pairs on the outer side of the circular ring. The support frame 3 is fitted into the mixed-state moving bed 1 to fix and support the cylindrical cylinder 2, the metal mesh 7, and the fiber filter layer 6. The outer ends of its multiple support plates 31 abut against the inner sidewall of the mixed-state moving bed 1. The cylindrical cylinder 2 is fitted onto the circular ring of the support frame 3.

[0029] The metal mesh 7 is fitted onto the outside of the cylinder 2 and located above the support 3, with its outer periphery abutting against the inner wall of the mixed-state moving bed 1. The metal mesh 7 is made of stainless steel with an aperture of 5x5 to 10x10 mm and a wire diameter of 1 mm.

[0030] The fiber filter layer 6 is fitted onto the outside of the cylinder 2, above the metal mesh 7, and fills the space between the cylinder 2 and the mixed-state moving bed 1. The fiber filter layer 6 is formed by stacking and wrapping bio-rope packing material, with a thickness of 20–30 cm. The unit volume weight of the fiber filter layer 6 is 80–110 g / L, and the nitrogen removal load of the bio-rope packing material used is 0.18–0.24 kg·N / m³. 3 .d, (based on the volume of the bio-rope packing). The fiber filter layer 6 further filters and intercepts suspended solids in the water flow. When water containing mud (mud refers to a mixture of sulfur powder, limestone powder, and sulfur autotrophic microorganisms) flows through the fiber filter layer, the mud particles actively adhere to the fibers of the bio-rope packing. When the fibers are filled with mud rich in sulfur autotrophic microorganisms, a mature fiber filter layer is formed, which can exert a strong filtration capacity. The sulfur autotrophic microorganisms attached to the fibers can actively capture small particles that are stable in the water, such as sulfur powder particles that are stable in a colloidal state. When water containing nitrate nitrogen flows through the mature fiber filter layer, a sulfur autotrophic denitrification reaction will continue to occur, promoting the growth of sulfur autotrophic microorganisms and the consumption of sulfur powder particles.

[0031] The mixed-state moving bed 1 also includes a clear water zone 12 and a buffer zone 13. The clear water zone 12 is located above the fiber filter layer 6, and the buffer zone 13 is located below the metal mesh 7 and above the sulfur autotrophic denitrification granular filter media. The outlet pipe 10 is located above the fiber filter layer 6 and connects to the clear water zone 12. The sulfur autotrophic denitrification granular filter media is poured into the mixed-state moving bed 1 through the top opening of the cylinder 2 and falls and accumulates naturally. The sulfur autotrophic denitrification granular filter media naturally accumulates on both sides of the bottom end of the cylinder 2, forming a slope. The buffer zone 13 refers to the space between the metal mesh 7 and the sloped sulfur autotrophic denitrification granular filter media.

[0032] The air-lift system includes an air inlet pipe 51, an air-lift pipe 52, and a pressure-relief truncated cone plate 53. The air-lift pipe 52 has an inlet end 54 and an outlet end 55. The air-lift pipe 52 is vertically positioned at the center of the cylinder 2. The air inlet pipe 51 passes through the side wall of the mixed-state moving bed 1 and extends into the inlet end 54, supplying compressed air into the air-lift pipe 52. The pressure-relief truncated cone plate 53 is fitted onto the outside of the air-lift pipe 52, with its top edge positioned between one-sixth and one-quarter of the length of the air-lift pipe 52 and the inlet end 54. The apex angle of the pressure-relief truncated cone plate 53 is 45° to 55°.

[0033] Sulfur autotrophic denitrification granular filter media is placed inside the mixed-state moving bed 1 and between the cylinder 2 and the air-lift pipe 52. The air-lift pipe 52, the pressure-relief cone plate 53, and the water distribution device 4 are surrounded by the sulfur autotrophic denitrification granular filter media. The particle size of the sulfur autotrophic denitrification granular filter media is 3-6 mm.

[0034] The pressure relief cone plate 53 is set up so that the sulfur autotrophic denitrification granular filter media that slides down to it is in a loose state, which can be easily sucked into the inlet end 54 of the air lift pipe 52. This avoids the excessive pressure between the sulfur autotrophic denitrification granular filter media in the lower part of the mixed filter bed 14, which would form an arch bridge effect. This solves the problem that the sulfur autotrophic denitrification granular filter media particles cannot freely slide down to the vicinity of the inlet end 54.

[0035] An airlift system uses compressed air to power the movement of the autotrophic denitrification granular filter media within the mixed-state moving bed 1. A small amount of compressed air is introduced into the inlet 54 of the airlift pipe 52. Air bubbles rise along the airlift pipe 52, propelling the water upwards. Additionally, the mixing of air bubbles and water within the airlift pipe 52 lowers the overall density of the liquid, creating a pressure difference that pushes the water upwards as well. The water flow, carrying the autotrophic denitrification granular filter media, slurry, and microorganisms, is transported to the outlet 55 of the airlift pipe 52. The water carrying these components is then ejected from the outlet 55 and falls back onto the top of the cylinder 2. After the sulfur autotrophic denitrification granular filter media at the bottom of the mixed-state moving bed 1 is air-lifted, voids are formed, reducing the supporting force on the upper granular filter media. The upper granular filter media slides down due to the collapse of its original foundation. This effect continues to propagate to all granular filter media, causing all sulfur autotrophic denitrification granular filter media to move continuously and slowly downwards. During this continuous and slow movement, the movement rate of the sulfur autotrophic denitrification granular filter media is not uniform, and friction occurs between adjacent granular filter media, generating slurry while simultaneously renewing the surface of the granular filter media. At the same time, some of the biofilm originally growing on the surface of the sulfur autotrophic denitrification granular filter media is sloughed off, causing the denitrification system within the mixed-state filter bed 14 to gradually evolve into a mixed denitrification system of sulfur autotrophic denitrification granular filter media, slurry, and microorganisms. The continuous and slow movement of the sulfur autotrophic denitrification granular filter media also solves the problem of localized clogging in the filter bed. During the continuous movement of the granular filter media, the previously clogged areas are loosened and their water flow capacity is restored.

[0036] The airlift system achieves the purpose of moving the sulfur autotrophic denitrification granular filter media, slurry, and microorganisms at the bottom of the mixed-state filter bed 14 upward with the water flow. During this movement, the sulfur autotrophic denitrification granular filter media, slurry, and microorganisms come into full contact with the nitrate nitrogen in the wastewater, thereby improving the denitrification efficiency.

[0037] The water distribution device 4 is located in the middle of the mixed moving bed 1, sleeved outside the air lift pipe 52, and above the pressure relief cone plate 53. The inlet pipe 9 is connected to the water distribution device 4, supplying the nitrate nitrogen wastewater to be treated to the water distribution device 4. The water distribution device 4 is equipped with a water distribution port. Water enters from the middle of the mixed moving bed 1 and flows into the mixed filter bed 14 in two directions, upward and downward, which shortens the water flow path from the inlet pipe 9 to the outlet pipe 10 by half. This reduces the pH difference between the inlet and outlet water, ensuring that the pH value throughout the mixed filter bed is within the range suitable for sulfur autotrophic denitrification, thus solving the problem of a large pH gradient difference along the water flow direction. After passing through the water distribution port, the influent is divided into two streams, one upward and one downward. The upward stream passes through the autotrophic denitrification granular filter media and enters the fiber filter layer 6. After filtration by the fiber filter layer 6, it enters the clear water zone 12. The downward stream passes through the autotrophic denitrification granular filter media and enters the inlet end 54 at the bottom of the airlift pipe 52. It is then lifted by air to the outlet end 55 of the airlift pipe 52, falls into the cylinder 2, and then flows downward through the autotrophic denitrification granular filter media inside the cylinder 2, reaching the buffer zone 13, where it merges with the upward stream. The water then flows upward through the fiber filter layer 6, which further intercepts suspended sludge and microorganisms. After entering the clear water zone 12, the water is discharged. The flow rate ratio of the upward and downward streams can be controlled by the strength of the airlift, i.e., by controlling the flow rate of compressed air.

[0038] The air-lift reflux circulation pipe 8 is provided with a first valve pre-pipe 81, a first valve 82, and a first valve post-pipe 83 connected in sequence. One end of the first valve post-pipe 83 extends below the pressure relief cone plate 53, and the other end is connected to the first valve 82. One end of the first valve pre-pipe 81 passes through the side wall of the mixed-state moving bed 1, extends into the cylinder 2, and is located between the outlet end 55 and the sulfur autotrophic denitrification granular filter media; the other end is connected to the first valve 82. The air-lift reflux circulation pipe 8 is used to return the liquid at the top of the cylinder to the bottom of the mixed-state filter bed 14, that is, near the inlet end 54 of the air-lift pipe 52.

[0039] The sedimentation and sludge removal device 11 includes a radial flow sedimentation tank 111, an inlet central cylinder 112, a sludge removal pipe 113, a sludge removal valve 114, a second valve 115, and a third valve 116. The inlet central cylinder 112 is vertically installed at the top center of the radial flow sedimentation tank 111. One end of the second valve 115 is connected to the front pipe 81 of the first valve, and the other end is connected to the inlet central cylinder 112. One end of the third valve 116 is connected to the rear pipe 83 of the first valve, and the other end is connected to the radial flow sedimentation tank 111. The third valve 116 is located below the second valve 115. One end of the sludge removal valve 114 is connected to the bottom of the radial flow sedimentation tank 111, and the other end is connected to the sludge removal pipe 113. When the treatment load of the autotrophic denitrification mixed moving bed is too high, or the water flow resistance of the filter bed is too large, the sludge and reaction byproducts in the mixed moving bed 1 can be discharged through the sedimentation and sludge removal device 11. The second valve 115 is used to guide the liquid with a high sludge content at the top of the cylinder 2 to the radial flow sedimentation tank 111 through the front pipe 81 of the first valve for sedimentation and sludge removal. The third valve 116 is used to return the clear liquid from the upper part of the radial flow sedimentation tank to the air lift return circulation pipe 8, and then transport it to the bottom of the mixed-state filter bed 14, that is, near the inlet end 54 of the air lift pipe 52, to achieve sludge removal treatment of the liquid in the mixed-state moving bed 1. The settled sludge in the radial flow sedimentation tank 111 is discharged through the sludge discharge valve 114 and the sludge discharge pipe 113. The installation of this sedimentation and sludge discharge device 11 does not require the mixed-state moving bed to stop operating.

[0040] Figure 1 The arrows in the diagram indicate the direction of water flow within the mixed-state moving bed 1 in this embodiment.

[0041] Example 2

[0042] The present invention provides a sulfur autotrophic denitrification method using a sulfur autotrophic denitrification mixed-state moving bed as described in Example 1, comprising the following steps:

[0043] Step a: Sulfur autotrophic denitrification granular filter media and powder are added into the mixed moving bed 1 through the top opening of the cylinder 2, preventing the sulfur autotrophic denitrification granular filter media from entering the air lift pipe. The height of the sulfur autotrophic denitrification granular filter media in the cylinder is level with the height of the fiber filter layer 6. The sulfur autotrophic denitrification granular filter media falls naturally in the mixed moving bed 1 and naturally accumulates on both sides of the bottom end of the cylinder 2 to form a slope. The mass of the powder is 10% to 50% of the weight of the sulfur autotrophic denitrification granular filter media. The powder includes sulfur powder and limestone powder. The mass ratio of sulfur powder to limestone powder is 7:3. The particle size of sulfur powder is 20μm to 200μm, the particle size of limestone powder is 20μm to 200μm, and the particle size of sulfur autotrophic denitrification granular filter media is 3 to 6mm.

[0044] Step b: Wastewater with a nitrate nitrogen content of 50–300 mg / L and a pH value of 8.5–11 is transported to the water distribution device 4 through the inlet pipe 9. The wastewater is divided into upward and downward flows through the distribution port and enters the mixed moving bed 1, where it comes into contact with the sulfur autotrophic denitrification granular filter media. The powder forms a slurry upon contact with the wastewater. The pores between the sulfur autotrophic denitrification granular filter media are filled with the slurry, microbubbles, water, and sulfur autotrophic microorganisms, forming a sulfur autotrophic denitrification granular filter media and slurry (containing…). The mixed-state filter bed 14 is a mixture of sulfur powder, limestone powder, and sulfur autotrophic microorganisms. In this step, the water distribution device 4 introduces water from the middle of the mixed-state moving bed 1 and flows into the mixed-state moving bed 1 in two directions, which shortens the water flow path from the inlet pipe 9 to the outlet pipe 10 by half. This reduces the pH difference between the inlet and outlet water, ensuring that the pH value of all parts of the mixed-state filter bed 14 is within the range suitable for sulfur autotrophic denitrification, thus solving the problem of a large pH gradient difference along the water flow direction. After the inlet water passes through the water distribution port, it splits into two streams. One stream flows upward through the autotrophic denitrification granular filter media and into the fiber filter layer 6. After being filtered by the fiber filter layer 6, it enters the clear water zone 12. The other stream flows downward through the autotrophic denitrification granular filter media and into the inlet end 54 at the bottom of the airlift pipe 52. It is then lifted by air to the outlet end 55 of the airlift pipe 52, and falls into the cylinder 2. It then flows downward through the autotrophic denitrification granular filter media inside the cylinder 2, reaching the buffer zone 13, where it merges with the upward stream. The water then flows upward through the fiber filter layer 6, which further intercepts suspended sludge and microorganisms. After entering the clear water zone 12, the water is discharged outward. The flow rate ratio of the upward and downward streams can be controlled by the strength of the airlift, i.e., by controlling the flow rate of compressed air.

[0045] Step c: Compressed air is introduced to circulate the autotrophic denitrification granular filter media, slurry, and autotrophic microorganisms from the bottom to the top and back to the bottom of the mixed-state filter bed. Simultaneously, autotrophic denitrification of nitrate nitrogen in the wastewater is performed. In this step, compressed air is supplied to the airlift pipe 52 through the air inlet pipe 51. The compressed air mixes with water in the airlift pipe 52, creating a pressure difference where the water pressure outside the pipe is greater than the water pressure inside. Simultaneously, the air rises along the airlift pipe 52, jointly propelling the water flow upwards. This upward movement of the water carries the autotrophic denitrification granular filter media, slurry, and autotrophic microorganisms at the bottom of the mixed-state filter bed 14 upwards as well. The denitrifying granular filter media, slurry, and sulfur autotrophic microorganisms are sprayed outward from the outlet 55 with the water flow and fall into the cylinder outside the airlift pipe 52, where they accumulate. As the water flows upward within the airlift pipe 52, the amount of sulfur autotrophic denitrifying granular filter media below the pressure relief cone plate 54 decreases, resulting in voids at the bottom of the mixed-state filter bed 14. This reduces the support force on the upper sulfur autotrophic denitrifying granular filter media, causing it to slowly move downward under gravity and the downward water flow. When the sulfur autotrophic denitrifying granular filter media reaches the bottom of the mixed-state filter bed 14, it is drawn into the airlift pipe 52 and moves upward with the water flow, achieving a bottom-to-top-to-bottom circulation of the sulfur autotrophic denitrifying granular filter media, slurry, and sulfur autotrophic microorganisms. During this circulation, the sulfur autotrophic microorganisms fully contact nitrate nitrogen and sulfur, greatly promoting their activity and denitrification capacity.

[0046] In this step, the fiber filter layer 6 filters and intercepts the denitrified water. The resulting clean water enters the clean water zone 12 and is discharged through the outlet pipe 10. The nitrate nitrogen content in the water discharged from the outlet pipe 10 is generally 5-20 mg / L. The upward water flow carries the slurry, sulfur autotrophic microorganisms, and biofilm debris upward through the metal mesh 7 and the fiber filter layer 6 in sequence. The fiber filter layer 7 filters and intercepts the sulfur autotrophic microorganisms, biofilm debris, and sulfur powder and limestone powder in the slurry. When water containing mud (mud refers to a mixture formed by sulfur powder, limestone powder, and sulfur autotrophic microorganisms) flows through the fiber filter layer, the mud particles will actively adhere to the fiber filaments of the bio-rope packing. When the fiber filaments are filled with mud rich in sulfur autotrophic microorganisms, a mature fiber filter layer is formed, which can exert a strong filtration capacity. The sulfur autotrophic microorganisms attached to the fiber filaments can actively capture small particles that are stable in the water, such as sulfur powder particles that are stable in a colloidal state. When water containing nitrate nitrogen flows through a mature fiber filter bed, a sulfur autotrophic denitrification reaction continues to occur, promoting the growth of sulfur autotrophic microorganisms and the consumption of sulfur powder particles.

[0047] As the mud content of the fiber filter layer 6 increases, its porosity decreases. Mud particles that rise due to gas production are trapped below the fiber filter layer 6, forming a mud cake layer, which also has excellent filtration capabilities. This mud cake layer adheres tightly to the fiber filter layer 6 because gas is also produced inside the mud cake due to the autotrophic denitrification reaction. The presence of air bubbles lowers the density of the mud cake, causing it to float and adhere to the fiber filter layer 6 by buoyancy. As the thickness of the mud cake layer increases to 3 mm, its excessive weight causes it to disintegrate and sink into the liquid in the mixed-state filter bed 14.

[0048] Step d: Open the first valve 82, close the second valve 115 and the third valve 116. The liquid at the top of the cylinder 2 is transported to the bottom of the mixed filter bed through the air lift reflux circulation pipe 8 for reflux and is drawn back into the air lift pipe 52 for circulation.

[0049] When the inlet water pressure is greater than 50 kPa, close the first valve 82 and open the second valve 115 and the third valve 116 to perform sludge discharge. After the sludge discharge is completed, open the first valve 82 and close the second valve 115 and the third valve 116 to reset.

[0050] Example 3: Specific Treatment Case of Wastewater Containing Nitrate Nitrogen

[0051] refer to Figure 1 and Figure 2 This embodiment uses a sulfur autotrophic denitrification mixed moving bed from Example 1 and a sulfur autotrophic denitrification method from Example 2 to treat nitrate nitrogen wastewater from an electroplating company.

[0052] In this embodiment, the pH of the nitrate nitrogen wastewater generated by the enterprise is adjusted by the alkaline dosing system 15 and the alkalinity adjustment tank 16. After adjustment, the nitrate nitrogen concentration in the wastewater is 200 mg / L and the pH value is 10.4. The adjusted wastewater is transported to the water distribution device 4 through the inlet pipe 9 and then sent to the sulfur autotrophic denitrification mixed moving bed for sulfur autotrophic denitrification treatment.

[0053] When the nitrate nitrogen concentration in the effluent of the sulfur autotrophic denitrification mixed moving bed exceeds 30 mg / L, it indicates that the denitrification capacity is insufficient. The influent flow rate should be reduced, and powder composed of sulfur powder and limestone powder should be added to the moving bed.

[0054] When the inlet water pressure exceeds 50 kPa, it indicates that there is too much sludge in the moving bed, which increases the water flow resistance and requires sludge removal.

[0055] The sludge removal operation is as follows:

[0056] Open the second valve 115 and the third valve 116, and close the first valve 82. The liquid in the upper part of the cylinder 2 flows into the radial flow sedimentation tank 111 through the second valve 115. The clear liquid at the top after sedimentation flows into the air-lift return circulation pipe 8 through the third valve 116 and is transported to the bottom of the mixed-state filter bed 14. During the sludge discharge, the sulfur autotrophic denitrification mixed moving bed continues to operate normally. After the sludge discharge process is completed, close the second valve 115 and the third valve 116, and open the first valve 82 to reset it. The liquid in the upper part of the cylinder 2 flows back to the bottom of the mixed-state filter bed 14 through the air-lift return circulation pipe 8. The sludge at the bottom of the radial flow sedimentation tank 111 is discharged to the outside through the sludge discharge pipe 113.

[0057] The volumetric loading rate of the sulfur autotrophic denitrification mixed moving bed in this embodiment, calculated based on the packing volume, is 0.86 kg N / m³. 3 .d.

[0058] Example 4: Optimization of the mass ratio of sulfur-autotrophic denitrification granular filter media to powder media

[0059] This embodiment uses a sulfur autotrophic denitrification mixed-state moving bed from Example 1. Wastewater with a nitrate nitrogen concentration of 200 mg / L and a pH of 10.4 is used as the influent. A blank control group is set up without powder, and six different mass ratios of powder to sulfur autotrophic denitrification granular filter media are set up as treatment groups. Specifically, the mass of powder added is 5%, 10%, 20%, 40%, 50%, and 60% of the mass of sulfur autotrophic denitrification granular filter media. The sulfur autotrophic denitrification method from Example 2 is used to denitrify the wastewater. After 30 days of treatment, the denitrification load of each treatment group and the blank control is measured.

[0060] Measurements showed that when the powder was added at a ratio of 10% of the mass of the sulfur-autotrophic denitrification granular filter media, the denitrification load was 0.4 kg N / m³. 3 When the powder is added at a ratio of 50% of the mass of the sulfur-autotrophic denitrification granular filter media, the denitrification load is 1.1 kg N / m³. 3 .d. When the powder is added at a ratio of 5% of the mass of the sulfur autotrophic denitrification granular filter media, or when no powder is added, the denitrification load is less than 0.3 kg N / m. 3 Furthermore, the growth rate of sulfur autotrophic microorganisms in the moving bed is relatively slow, which is not conducive to improving denitrification efficiency. When the powder is added at a ratio of 60% of the mass of the sulfur autotrophic denitrification granular filter media, the water resistance in the mixed moving bed 1 increases significantly, which can easily cause piping in the filter bed and poses a risk of bed turnover. Therefore, in this invention, the mass of powder added is 10%-50% of the mass of the sulfur autotrophic denitrification granular filter media, and the optimal range for the proportion of powder added is 30-40% of the mass of the sulfur autotrophic denitrification granular filter media.

[0061] The above descriptions are merely some embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A sulfur autotrophic denitrification mixed-state moving bed, characterized in that, The system includes a mixed-state moving bed, a cylinder, a support frame, a water distribution device, an air-lift system, a fiber filter layer, an inlet pipe, an outlet pipe, an air-lift reflux circulation pipe, and a sedimentation and sludge removal device. The cylinder, support frame, air-lift system, and water distribution device are all located within the mixed-state moving bed. The support frame is detachably mounted within the mixed-state moving bed, and the cylinder is detachably mounted on the support frame. The air-lift system includes an air inlet pipe, an air-lift pipe, and a pressure-relief cone plate. The air-lift pipe is vertically positioned at the center of the cylinder and has an inlet end and an outlet end. The air inlet pipe passes through the... The sidewall of the mixed-state moving bed extends into the inlet end. The pressure relief cone plate is sleeved on the outside of the air-lift pipe and located above the inlet end. The water distribution device is located in the middle of the mixed-state moving bed, sleeved on the outside of the air-lift pipe and located above the pressure relief cone plate. The fiber filter layer is sleeved on the outside of the cylinder, located above the support, and fills the space between the cylinder and the mixed-state moving bed. Sulfur autotrophic denitrification granular filter media is placed inside the cylinder and the mixed-state moving bed. The sulfur autotrophic denitrification granular filter media is located at the bottom end of the cylinder. The filter bed is naturally stacked on both sides to form a slope. The air lift pipe, the pressure relief cone plate, and the water distribution device are surrounded by the sulfur autotrophic denitrification granular filter media. The inlet pipe is connected to the water distribution device, and the outlet pipe is located above the fiber filter layer. One end of the air lift reflux circulation pipe extends below the pressure relief cone plate, and the other end passes through the side wall of the mixed moving bed, extends into the cylinder, and is located between the outlet end and the sulfur autotrophic denitrification granular filter media. The sedimentation and sludge discharge device includes a radial flow sedimentation tank, an inlet central cylinder, a sludge discharge pipe, a sludge discharge valve, a second valve, and... The third valve, the air lift reflux circulation pipe is provided with a first valve front pipe, a first valve and a first valve rear pipe connected in sequence, the water inlet center cylinder is installed at the top center of the radial flow sedimentation tank, one end of the second valve is connected to the first valve front pipe and the other end is connected to the water inlet center cylinder, one end of the third valve is connected to the first valve rear pipe and the other end is connected to the radial flow sedimentation tank, the third valve is located below the second valve, one end of the sludge discharge valve is connected to the bottom of the radial flow sedimentation tank and the other end is connected to the sludge discharge pipe.

2. The sulfur autotrophic denitrification mixed-state moving bed according to claim 1, characterized in that, It also includes a metal mesh and an airlift reflux circulation pipe. The metal mesh is sleeved on the outside of the cylinder, located below the fiber filter layer and above the support, and its outer periphery abuts against the side wall of the mixed-state moving bed.

3. The sulfur autotrophic denitrification mixed-state moving bed according to claim 2, characterized in that, The mixed-state moving bed is provided with a clear water zone and a buffer zone. The clear water zone is located above the fiber filter layer, and the water outlet pipe is connected to the clear water zone. The buffer zone is located below the metal mesh and above the sulfur autotrophic denitrification granular filter media.

4. The sulfur autotrophic denitrification mixed-state moving bed according to claim 2, characterized in that, The water distribution device is equipped with a water distribution port. The fiber filter layer is filled by stacking and wrapping biological rope packing material, with a thickness of 20-30cm. The metal mesh has a pore size of 5x5mm-10x10mm and a wire diameter of 1mm. The apex angle of the pressure relief cone plate is 45-55°. The distance between the top of the pressure relief cone plate and the inlet end is one-sixth to one-quarter of the length of the air lift pipe.

5. A method for sulfur autotrophic denitrification using a mixed-state moving bed for sulfur autotrophic denitrification as described in any one of claims 1-4, characterized in that, Includes the following steps: Step a: Add sulfur autotrophic denitrification granular filter media and powder to prevent the sulfur autotrophic denitrification granular filter media from entering the air stripping pipe. The mass of the powder is 10% to 50% of the weight of the sulfur autotrophic denitrification granular filter media. Step b: Nitrate nitrogen wastewater is introduced into the water distribution device, forming water flows in both upward and downward directions. The water enters the mixed moving bed, where the powder material forms a slurry upon contact with the nitrate nitrogen wastewater. The pores between the sulfur autotrophic denitrification granular filter media are filled with the slurry, microbubbles, water, and sulfur autotrophic microorganisms, forming a mixed filter bed composed of sulfur autotrophic denitrification granular filter media, slurry, and sulfur autotrophic microorganisms. The nitrate nitrogen content in the nitrate nitrogen wastewater is 50~300 mg / L, and the pH value is 8.5~11. Step c: Compressed air is introduced into the airlift pipe to drive the sulfur autotrophic denitrification granular filter media, slurry, and sulfur autotrophic microorganisms to circulate from the bottom of the mixed-state filter bed to the top of the mixed-state filter bed and back to the bottom of the mixed-state filter bed, so as to carry out sulfur autotrophic mixed-state denitrification treatment on nitrate nitrogen wastewater. Step d: Open the first valve and close the second and third valves. The liquid at the top of the cylinder is transported to the bottom of the mixed filter bed through the air lift reflux circulation pipe for reflux and is then drawn back into the air lift pipe for circulation.

6. The sulfur autotrophic denitrification method according to claim 5, characterized in that, It also includes step e, where when the inlet water pressure is greater than 50 kPa, the first valve is closed and the second and third valves are opened to perform sludge discharge. After the sludge discharge is completed, the first valve is opened and the second and third valves are closed to reset.

7. The sulfur autotrophic denitrification method according to claim 5, characterized in that, The particle size of the sulfur autotrophic denitrification granular filter media is 3~6mm.

8. The sulfur autotrophic denitrification method according to claim 5, characterized in that, The powder comprises sulfur powder and limestone powder, wherein the mass ratio of sulfur powder to limestone powder is 7:

3.

9. The sulfur autotrophic denitrification method according to claim 8, characterized in that, The sulfur powder has a particle size of 20μm to 200μm, and the limestone powder has a particle size of 20μm to 200μm.

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