Sulfur autotrophic nitrogen removal mixed moving bed and sulfur autotrophic nitrogen removal method

Abstract

The invention discloses a sulfur autotrophic nitrogen removal mixed moving bed which comprises a mixed moving bed body, a cylinder, a support, a water distribution device, a gas stripping system, a fiber filter layer, a water inlet pipe and a water outlet pipe, the cylinder, the support, the gas stripping system and the water distribution device are all located in the mixed moving bed body, the cylinder is clamped on the support, the gas stripping system comprises a gas inlet pipe, a gas stripping pipe and a pressure relief frustum plate, and the fiber filter layer is arranged on the gas stripping pipe. The gas stripping pipe is vertically arranged in the center of the cylinder and provided with an inlet end and an outlet end, the gas inlet pipe extends into the inlet end, the gas stripping pipe is sleeved with the pressure relief frustum plate and located above the inlet end, the gas stripping pipe is sleeved with the water distribution device and located above the pressure relief frustum plate, and the cylinder is sleeved with the fiber filter layer and located above the support. The pressure relief frustum plate is arranged in the cylinder and is filled between the cylinder and the mixed moving bed body, a sulfur autotrophic particle filter material is placed in the cylinder and the mixed moving bed body, the gas stripping pipe, the pressure relief frustum plate and the water distribution device are surrounded by the sulfur autotrophic particle filter material, the water inlet pipe is communicated with the water distribution device, and the water outlet pipe is positioned at the top of the side surface of the mixed moving bed body.

Description

Technical Field

[0001] The invention relates to the technical field of biological denitrification of sewage, and in particular to a sulfur autotrophic denitrification mixed-state moving bed and a sulfur autotrophic denitrification method. Background Art

[0002] Sulfur autotrophic denitrification refers to the process of using sulfur or pyrite powder as electron donors and autotrophic bacteria to carry out denitrification. In recent years, the application of sulfur autotrophic denitrification technology in China has begun to rise, and the main process mode adopts the filter mode. Sulfur, pyrite powder, limestone and other powders are mixed and sintered into stable and hard particles. The above particles are placed in the filter bed as fillers, and the water to be treated flows through the filter material in the form of upward or downward flow to react. Sulfur autotrophic microorganisms grow on the surface of the filter material particles and exist in the form of biofilm, similar to ordinary biological filters (BAF).

[0003] However, the main problem of the existing sulfur autotrophic denitrification process in the biofilter model is its low efficiency, mainly the following problems: (1) The mass transfer efficiency of the reaction. The material (sulfur powder) exists in the form of coarse particles (the particle size is mostly between 4-12mm), and only the material on the surface of the particles can participate in the reaction. Obviously, the specific surface area of ​​the coarse particles is limited, much smaller than the specific surface area of ​​the microparticle form. The specific surface area of ​​the material in contact with water is limited, which is the main reason for the low reaction efficiency; (2) The autotrophic microorganisms participating in the reaction grow on the surface of the filler particles and exist in the form of biofilms, resulting in the surface of the filler particles being occupied by the biofilm. The biofilm blocks the contact between water and the material, which further reduces the specific surface area of ​​the reaction. It is contradictory to provide as large a surface area as possible for the filler to contact with water, while at the same time hoping that more biofilms will grow on the surface of the filler to increase the total amount of organisms; (3) It cannot guarantee that the water flow can flow evenly through the filter bed. Due to various reasons such as water distribution and local blockage, the hydraulic distribution will be affected, so that the fillers in each area will not be in a high-efficiency state, resulting in a decrease in overall efficiency; (4) The influence of uneven pH value. There is a gradient in pH distribution along the water flow direction. The pH area 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 object of the present invention is to provide a sulfur autotrophic denitrification mixed-state 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 bracket, a water distribution device, an air stripping system, a fiber filter layer, a water inlet pipe and a water outlet pipe, wherein the cylinder, the bracket, the air stripping system and the water distribution device are all located in the mixed-state moving bed body, the bracket is detachably mounted in the mixed-state moving bed body, the cylinder is detachably mounted on the bracket, the air stripping system comprises an air inlet pipe, an air stripping pipe and a pressure relief cone plate, the air stripping pipe is vertically arranged in the center of the cylinder, the air stripping pipe is provided with an inlet end and an outlet end, and the air inlet pipe passes through the side wall of the mixed-state moving bed body , and extends into the inlet end, the pressure relief cone plate is sleeved on the outside of the gas lift pipe and is located above the inlet end, the water distribution device is in the middle of the mixed-state moving bed, sleeved on the outside of the gas lift pipe and above the pressure relief cone plate, the fiber filter layer is sleeved on the outside of the cylinder, located above the bracket, and filled between the cylinder and the mixed-state moving bed, sulfur autotrophic denitrification granular filter material is placed in the cylinder and the mixed-state moving bed, the gas lift pipe, the pressure relief cone plate and the water distribution device are surrounded by the sulfur autotrophic denitrification granular filter material, 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-state moving bed.

[0006] In some embodiments, the present invention also 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 bracket, and its outer periphery is abutted against the side wall of the mixed-state moving bed. One end of the air lift reflux circulation pipe extends under the pressure relief cone plate, and the other end passes through the side wall of the mixed-state moving bed, extends into the cylinder, and is located between the outlet end and the sulfur autotrophic denitrification granular filter material.

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

[0008] In some embodiments, the water distribution device is provided with a water distribution port, the fiber filter layer is formed by stacking and filling a biological rope filler, the thickness of which is 20 to 30 cm, the pore size of the metal mesh is 5x5 to 10x10 mm, the wire diameter is 1 mm, the top angle of the pressure relief cone plate is 45 to 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 also includes a sedimentation and mud discharge device, which includes a radial flow sedimentation tank, a water inlet center cylinder, a mud discharge pipe, a mud 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 which are 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 mud discharge valve is connected to the bottom of the radial flow sedimentation tank, and the other end is connected to the mud discharge pipe.

[0010] According to another aspect of the present invention, there is provided a sulfur autotrophic denitrification method using a sulfur autotrophic denitrification mixed-state moving bed, characterized in that it comprises the following steps:

[0011] Step a, adding sulfur autotrophic denitrification granular filter material and powder to prevent the sulfur autotrophic denitrification granular filter material from entering the air stripping pipe, the mass of the powder being 10% to 50% of the weight of the sulfur autotrophic denitrification granular filter material;

[0012] Step b, introducing nitrate nitrogen wastewater into the water distribution device to form water flows in two directions, upward and downward, and entering the mixed moving bed body, the powder meets the nitrate nitrogen wastewater to form a slurry, and the pores between the sulfur autotrophic denitrification granular filter materials are filled with slurry, microbubbles, water and sulfur autotrophic microorganisms to form a mixed filter bed of sulfur autotrophic denitrification granular filter materials, 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, introducing compressed air into the air lift pipe to circulate the sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms from the bottom of the mixed filter bed-the top of the mixed filter bed-the bottom of the mixed filter bed, and perform sulfur autotrophic mixed denitrification treatment on the nitrate nitrogen wastewater;

[0014] Step d, open the first valve, close the second valve and the third valve, and the liquid at the top of the cylinder is transported to the bottom of the mixed filter bed through the gas lift reflux circulation pipe for reflux and is sucked into the gas lift pipe again for circulation.

[0015] In some embodiments, the method of the present invention also includes step e. When the water inlet pressure is greater than 50 KPa, the first valve is closed, and the second valve and the third valve are opened to perform sludge discharge treatment. After the sludge discharge treatment is completed, the first valve is opened, and 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 material is 3 to 6 mm.

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

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

[0019] Beneficial effects of the present invention: (1) The sulfur autotrophic denitrification mixed-state moving bed of the present invention has a unique structural design, and the volumetric load calculated according to the accumulated volume of the sulfur autotrophic denitrification granular filter material is: 0.8-1.2kg.N / m3.d, that is, the denitrification efficiency is 2.5-4 times higher than that of the ordinary sulfur autotrophic denitrification filter tank;

[0020] (2) The sulfur autotrophic denitrification mixed-state moving bed of the present invention can be operated continuously for 24 hours. The sulfur autotrophic denitrification particle filter material can be continuously moved up and down by the air stripping system and the water distribution device, thereby realizing the renewal of the particle filter material surface. There is no need to stop the machine for backwashing, nor is there a need to configure a special filter tank backwashing system, and there is no need to consider the disposal of a large amount of backwashing water;

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

[0022] (4) The sulfur autotrophic denitrification mixed-state moving bed of the present invention does not have the problem of local filter material clogging, does not need to be shut down regularly for manual cleaning, and has low equipment operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a sulfur autotrophic denitrification mixed-state moving bed of the present invention.

[0024] Figure 2 This is a specific application structure diagram of a sulfur autotrophic denitrification mixed-state moving bed according to Example 2 of the present invention. DETAILED DESCRIPTION

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

[0026] Example 1

[0027] refer to Figure 1 The present 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 stripping system, a fiber filter layer 6, a metal mesh 7, an air stripping reflux circulation pipe 8, a water inlet pipe 9, a water outlet pipe 10 and a sedimentation and mud discharge device 11. The cylinder 2, the support 3, the air stripping system, the water distribution device 4, the fiber filter layer 6 and the metal mesh 7 are all located in the mixed state moving bed body 1.

[0028] The support 3 is provided with a circular ring and a plurality of support plates 31, and the plurality of support plates 31 are symmetrically installed on the outer side of the circular ring. The support 3 is clamped in the mixed-state moving bed 1, and is used to fix the supporting cylinder 2, the metal mesh 7 and the fiber filter layer 6, and the outer ends of the plurality of support plates 31 abut against the inner side wall of the mixed-state moving bed 1. The cylinder 2 is clamped on the circular ring of the support 3.

[0029] The metal mesh 7 is sleeved on the outside of the cylinder 2 and located above the bracket 3, and its outer periphery abuts against the inner wall of the mixed-state moving bed 1. The metal mesh 7 is a stainless steel mesh with an aperture of 5x5-10x10mm and a wire diameter of 1mm.

[0030] The fiber filter layer 6 is sleeved on the outside of the cylinder 2, located above the metal mesh 7, and filled between the cylinder 2 and the mixed-state moving bed 1. The fiber filter layer 6 is formed by stacking and filling biological rope fillers, and its thickness is 20 to 30 cm. The unit volume gram weight of the fiber filter layer 6 is 80 to 110 g / L, and the nitrogen removal load of the biological rope filler used is 0.18 to 0.24 kg. N / m 3 .d, (measured by the filling volume of the biological rope filler). The fiber filter layer 6 further filters and intercepts the suspended matter 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 will actively adhere to the fiber filaments of the biological rope filler. When the fiber filaments are covered with mud rich in sulfur autotrophic microorganisms, a mature fiber filter layer is formed, which can exert a strong filtering ability. The sulfur autotrophic microorganisms attached to the fiber filaments can actively capture fine particles that are stably present in the water, such as sulfur powder particles that are stably present in a colloidal state. When water containing nitrate nitrogen flows through a mature fiber filter layer, sulfur autotrophic denitrification reaction will continue to occur, promoting the growth of sulfur autotrophic microorganisms and the consumption of sulfur powder particles.

[0031] A clean water area 12 and a buffer area 13 are also provided in the mixed-state moving bed 1. The clean water area 12 is located above the fiber filter layer 6, and the buffer area 13 is located below the metal mesh 7 and above the sulfur autotrophic denitrification granular filter material. The outlet pipe 10 is located above the fiber filter layer 6 and is connected to the clean water area 12. The sulfur autotrophic denitrification granular filter material is poured into the mixed-state moving bed 1 from the top opening of the cylinder 2 and naturally falls and accumulates. The sulfur autotrophic denitrification granular filter material naturally accumulates on both sides of the bottom end of the cylinder 2 to form a slope. The buffer area 13 refers to the area between the metal mesh 7 and the sloped sulfur autotrophic denitrification granular filter material.

[0032] The gas lift system includes an air inlet pipe 51, an air lift pipe 52 and a pressure relief cone plate 53. The air lift pipe 52 is provided with an inlet end 54 and an outlet end 55. The air lift pipe 52 is vertically placed 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 to provide compressed air to the air lift pipe 52. The pressure relief cone plate 53 is sleeved on the outside of the air lift pipe 52, and the distance between its top and the inlet end 54 is one sixth to one quarter of the length of the air lift pipe 52. The top angle of the pressure relief cone plate 53 is 45° to 55°.

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

[0034] A pressure relief cone plate 53 is provided to make the sulfur autotrophic denitrification granular filter material sliding down thereto in a loose state, so that it can be easily sucked into the inlet end 54 of the air lift pipe 52, thereby avoiding excessive pressure between the sulfur autotrophic denitrification granular filter materials at the bottom of the mixed filter bed 14 to form an arch bridge effect, thereby solving the problem that the sulfur autotrophic denitrification granular filter material particles cannot freely slide down to the vicinity of the inlet end 54.

[0035] The air lift system is used to provide the power for the movement of the sulfur autotrophic denitrification granular filter material in the mixed-state moving bed 1 through compressed air. A small amount of compressed air is introduced into the inlet end 54 of the air lift pipe 52, and the air bubbles float up along the air lift pipe 52, pushing the water flow upward. In addition, the bubbles and water in the air lift pipe 52 are mixed, so that the overall specific gravity of the liquid in the pipe is reduced, and the pressure outside the inlet end 54 of the air lift pipe 52 is greater than the pressure inside the pipe, forming a pressure difference to push the water flow upward. The water flow carries the sulfur autotrophic denitrification granular filter material, slurry, and microorganisms, and transports them to the outlet end 55 of the air lift pipe 52. The water flow carrying the sulfur autotrophic denitrification granular filter material, slurry, and microorganisms is ejected from the outlet end 55 and falls back on the top of the cylinder 2. The sulfur autotrophic denitrification granular filter material at the bottom of the mixed-state moving bed 1 is airlifted to form a gap, and the support force on the upper granular filter material decreases. The upper granular filter material slides down due to the collapse of the original foundation. This effect is continuously transmitted to all granular filter materials, causing all sulfur autotrophic denitrification granular filter materials to move downward continuously and slowly. In the process of continuous and slow movement, the movement rate of the sulfur autotrophic denitrification granular filter material is not consistent, and friction is generated between adjacent granular filter materials, which generates slurry and updates the surface of the granular filter material. At the same time, part of the biofilm originally grown on the surface of the sulfur autotrophic denitrification granular filter material is peeled off, so that the denitrification system in the mixed-state filter bed 14 gradually evolves into a mixed denitrification system of sulfur autotrophic denitrification granular filter material, slurry and microorganisms. The continuous and slow movement of the sulfur autotrophic denitrification granular filter material can also solve the problem of local blockage of the filter bed. In the continuous movement of the granular filter material, the originally blocked area will be loosened and the water flow capacity will be restored.

[0036] The air lift system realizes the purpose of moving the sulfur autotrophic denitrification granular filter material, slurry and microorganisms at the bottom of the mixed filter bed 14 upward with the water flow. During this movement process, the sulfur autotrophic denitrification granular filter material, slurry and microorganisms are fully in 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-state moving bed 1, sleeved on the outside of the gas lift pipe 52, and located above the pressure relief cone plate 53. The water inlet pipe 9 is connected to the water distribution device 4 to transport the nitrate nitrogen wastewater to be treated to the water distribution device 4. The water distribution device 4 is provided with a water distribution port. The water distribution device 4 takes in water from the middle of the mixed-state moving bed 1, and flows into the mixed-state filter bed 14 in two directions, upward and downward, so that the water flow distance from the water inlet pipe 9 to the water outlet pipe 10 is shortened by half, which also reduces the pH difference between the inlet water and the outlet water, so that the pH value of each place in the entire mixed filter bed is within the range suitable for sulfur autotrophic denitrification, solving the problem of large pH gradient difference along the water flow direction. After passing through the water distribution port, the incoming water is divided into two water flows, one in an upward direction and the other in a downward direction. One upward water flow passes through the sulfur autotrophic denitrification granular filter material and enters the fiber filter layer 6, is filtered through the fiber filter layer 6, and enters the clean water area 12; the other downward water flow passes through the sulfur autotrophic denitrification granular filter material and enters the inlet end 54 at the bottom of the air lift pipe 52, is air lifted to the outlet end 55 of the air lift pipe 52, and then falls into the cylinder 2, and then passes downward through the sulfur autotrophic denitrification granular filter material in the cylinder 2, reaches the buffer zone 13, and merges with the upward water flow. After that, the water flows upward through the fiber filter layer 6, and the fiber filter layer 6 further intercepts the suspended mud and microorganisms. The water flows into the clean water area 12 and is discharged outward. The flow ratio of the upward and downward water flows can be controlled by the strength of the air lift, that is, by controlling the flow of compressed air.

[0038] The gas lift reflux circulation pipe 8 is provided with a first valve front pipe 81, a first valve 82 and a first valve rear pipe 83 which are connected in sequence. One end of the first valve rear 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 front 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 material, and the other end is connected to the first valve 82. The gas 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 gas lift pipe 52.

[0039] The sedimentation and sludge discharge device 11 comprises a radial flow sedimentation tank 111, a water inlet center tube 112, a sludge discharge pipe 113, a sludge discharge valve 114, a second valve 115 and a third valve 116. The water inlet center tube 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 first valve front pipe 81, and the other end is connected to the water inlet center tube 112, one end of the third valve 116 is connected to the first valve rear pipe 83, 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 discharge valve 114 is connected to the bottom of the radial flow sedimentation tank 111, and the other end is connected to the sludge discharge pipe 113. When the treatment load of the sulfur autotrophic denitrification mixed state moving bed is too high, or the water flow resistance of the filter bed is too large, the sludge and reaction by-products in the mixed state moving bed body 1 can be discharged through the sedimentation and sludge discharge device 11. The second valve 115 is used to guide the liquid with high sludge content at the top of the cylinder 2 to the radial flow sedimentation tank 111 through the first valve front pipe 81 for sedimentation and mud removal. The third valve 116 is used to return the upper clear liquid of the radial flow sedimentation tank to the air lift reflux circulation pipe 8, and then transport it to the bottom of the mixed filter bed 14, that is, near the inlet end 54 of the air lift pipe 52, to achieve mud removal of the liquid in the mixed moving bed body 1. The precipitated sludge in the radial flow sedimentation tank 111 is discharged through the mud discharge valve 114 and the mud discharge pipe 113. The sedimentation and mud discharge device 11 is set up without stopping the operation of the mixed moving bed.

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

[0041] Example 2

[0042] A sulfur autotrophic denitrification method of the present invention adopts a sulfur autotrophic denitrification mixed-state moving bed of Example 1, comprising the following steps:

[0043] Step a, adding sulfur autotrophic denitrification granular filter material and powder into the mixed-state moving bed 1 through the top opening of the cylinder 2, preventing the sulfur autotrophic denitrification granular filter material from entering the air lift pipe, until the height of the sulfur autotrophic denitrification granular filter material in the cylinder is level with the height of the fiber filter layer 6, the sulfur autotrophic denitrification granular filter material naturally falls in the mixed-state 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 material, the powder includes sulfur powder and limestone powder, the mass ratio of sulfur powder to limestone powder is 7:3, the particle size of the sulfur powder is 20μm to 200μm, the particle size of the limestone powder is 20μm to 200μm, and the particle size of the sulfur autotrophic denitrification granular filter material is 3 to 6mm;

[0044] Step b: The 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 water inlet 9. Through the water distribution port, the wastewater is divided into two directions of water flow, namely, upward and downward, and enters the mixed state moving bed 1, and contacts with the sulfur autotrophic denitrification granular filter material. The powder material meets the wastewater to form a slurry. The pores between the sulfur autotrophic denitrification granular filter materials are filled with slurry, microbubbles, water and sulfur autotrophic microorganisms to form the sulfur autotrophic denitrification granular filter material, slurry (containing A mixed filter bed 14 is prepared by mixing sulfur powder, limestone powder) and sulfur autotrophic microorganisms; in this step, the water distribution device 4 takes in water from the middle of the mixed moving bed body 1, and flows into the mixed moving bed body 1 in two directions, so that the water flow distance from the water inlet pipe 9 to the water outlet pipe 10 is shortened by half, and the pH difference between the inlet water and the outlet water is reduced, so that the pH value of each place in the entire mixed filter bed 14 is within the range suitable for sulfur autotrophic denitrification, which solves the problem of large pH gradient difference along the water flow direction. After passing through the water distribution port, the incoming water is divided into two directions of water flow. One upward water flow passes through the sulfur autotrophic denitrification granular filter material and enters the fiber filter layer 6, is filtered through the fiber filter layer 6, and enters the clean water area 12; the other downward water flow passes through the sulfur autotrophic denitrification granular filter material and enters the inlet end 54 at the bottom of the air lift pipe 52, is air lifted to the outlet end 55 of the air lift pipe 52, and then falls into the cylinder 2, and then passes downward through the sulfur autotrophic denitrification granular filter material in the cylinder 2, reaches the buffer zone 13, and merges with the upward water flow. After that, the water flows upward through the fiber filter layer 6, and the fiber filter layer 6 further intercepts the suspended mud and microorganisms. The water flows into the clean water area 12 and is discharged outward. The flow ratio of the upward and downward water flows can be controlled by the strength of the air lift, that is, by controlling the flow rate of the compressed air;

[0045] Step c, introducing compressed air, circulating the sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms from the bottom of the mixed filter bed-the top of the mixed filter bed-the bottom of the mixed filter bed, and at the same time, performing sulfur autotrophic mixed denitrification treatment on the nitrate nitrogen in the wastewater; in this step, compressed air is transported into the air lift pipe 52 through the air inlet pipe 51, and the compressed air and water in the air lift pipe 52 are mixed, so that the water pressure outside the air lift pipe 52 is greater than the water pressure inside the air lift pipe 52, forming a pressure difference, and at the same time, the air floats along the air lift pipe 52, and jointly pushes the water flow in the air lift pipe 52 to move upward, and when the water flow moves upward, it drives the sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms at the bottom of the mixed filter bed 14 to move upward together, and the above-mentioned sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms at the bottom of the mixed filter bed 14 move upward together. The sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms are ejected outward from the outlet end 55 along with the water flow and fall into the cylinder outside the air lift pipe 52 for accumulation; when the water flow moves upward in the air lift pipe 52, the sulfur autotrophic denitrification granular filter material below the pressure relief cone plate 54 is reduced, resulting in the formation of gaps at the bottom of the mixed filter bed 14, and the support force for the upper sulfur autotrophic denitrification granular filter material decreases. The upper sulfur autotrophic denitrification granular filter material slowly moves downward under the action of gravity and the downward water flow. When the sulfur autotrophic denitrification granular filter material moves downward to the bottom of the mixed filter bed 14, it is sucked into the air lift pipe 52 and moves upward along with the water flow, realizing the cyclic movement of the sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms from the bottom-top-bottom. During the cyclic movement process, the sulfur autotrophic microorganisms fully come into contact with nitrate nitrogen and sulfur, which greatly promotes the activity and denitrification capacity of the sulfur autotrophic microorganisms;

[0046] In this step, the fiber filter layer 6 filters and intercepts the water after denitrification treatment, and the clean water produced enters the clean water area 12 and is discharged by the outlet pipe 10. The nitrate nitrogen content in the outlet water of the outlet pipe 10 is generally 5-20 mg / L. The water flow in the upward direction drives the slurry, sulfur autotrophic microorganisms and biofilm debris to pass through the metal mesh 7 and the fiber filter layer 6 in sequence upward, and the fiber filter layer 7 filters and intercepts the sulfur autotrophic microorganisms, biofilm debris and sulfur powder and limestone powder in the slurry. When the 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 bond to the fiber filaments of the biological rope filler. When the fiber filaments are covered with mud rich in sulfur autotrophic microorganisms, a mature fiber filter layer is formed, which can exert a strong filtering ability. The sulfur autotrophic microorganisms attached to the fiber filaments can actively capture fine particles that are stably present in the water, such as sulfur powder particles that are stably present in a colloidal state. When water containing nitrate nitrogen flows through the mature fiber filter layer, sulfur autotrophic denitrification reaction will continue 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, the porosity will become smaller and smaller, and the mud particles that float due to gas production will be intercepted under the fiber filter layer 6 to form a mud cake layer, which also has a good filtering ability. This mud cake layer is closely attached to the fiber filter layer 6 because the mud cake is also producing gas due to the sulfur autotrophic denitrification reaction. The mud cake contains bubbles and its specific gravity decreases, so it floats up, and the buoyancy makes it closely attached to the fiber filter layer 6. As the thickness of the mud cake layer increases to 3mm, the mud cake layer will disintegrate and sink into the liquid of the mixed filter bed 14 due to its excessive weight;

[0048] Step d, open the first valve 82, close the second valve 115 and the third valve 116, and the liquid at the top of the cylinder 2 is transported to the bottom of the mixed filter bed through the gas stripping reflux circulation pipe 8 for reflux, and is sucked into the gas stripping pipe 52 again for circulation;

[0049] When the water inlet pressure is greater than 50Kpa, the first valve 82 is closed, and the second valve 115 and the third valve 116 are opened to carry out mud discharge treatment. After the mud discharge treatment is completed, the first valve 82 is opened, and the second valve 115 and the third valve 116 are closed to reset.

[0050] Example 3 Specific treatment example of nitrate-containing wastewater

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

[0052] In this embodiment, the pH value of the nitrate nitrogen wastewater generated by the enterprise is adjusted by the alkali solution dosing system 15 and the alkalinity adjustment tank 16. After the 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 water 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 means that the denitrification treatment capacity is insufficient. It is necessary to reduce the inlet flow rate and add powder composed of sulfur powder and limestone powder to the moving bed.

[0054] When the water inlet pressure exceeds 50KPa, it means that there is too much sludge in the moving bed, causing increased water flow resistance and sludge discharge operation is required.

[0055] The specific operation of mud discharge is as follows:

[0056] The second valve 115 and the third valve 116 are opened, and the first valve 82 is closed. The liquid in the upper part of the cylinder 2 flows into the radial flow sedimentation tank 111 through the second valve 115. The upper clear liquid after sedimentation treatment flows into the gas lift reflux circulation pipe 8 through the third valve 116 and is transported to the bottom of the mixed filter bed 14. The sulfur autotrophic denitrification mixed state moving bed still works normally during the sludge discharge. After the sludge discharge process is completed, the second valve 115 and the third valve 116 are closed, and the first valve 82 is opened to reset. The liquid in the upper part of the cylinder 2 flows back to the bottom of the mixed filter bed 14 through the gas lift reflux 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 load of a sulfur autotrophic denitrification mixed-state moving bed in this embodiment calculated based on the packing volume is 0.86Kg.N / m 3 .d.

[0058] Example 4 Optimization of the mass ratio of granular filter material and powder for sulfur autotrophic denitrification

[0059] This example uses a sulfur autotrophic denitrification mixed moving bed of Example 1, takes wastewater with a nitrate nitrogen concentration of 200 mg / L and a pH value of 10.4 as influent, sets no powder as a blank control group, sets 6 different powders and sulfur autotrophic denitrification granular filter material mass ratios as treatment groups, specifically, the mass of the added powder is 5%, 10%, 20%, 40%, 50%, and 60% of the mass of the sulfur autotrophic denitrification granular filter material, and adopts a sulfur autotrophic denitrification method of Example 2 to denitrify the wastewater. After 30 days of treatment, the denitrification load of each treatment group and the blank control is measured.

[0060] It has been determined that when the powder is added at a ratio of 10% of the mass of the sulfur autotrophic denitrification granular filter material, the denitrification load is 0.4Kg.N / m 3 .d, when the powder is added at a ratio of 50% of the mass of the sulfur autotrophic denitrification granular filter material, the denitrification load is 1.1Kg.N / m 3 .d. When the powder is added at a ratio of 5% of the mass of the sulfur autotrophic denitrification granular filter material or no powder is added, the denitrification load is less than 0.3Kg.N / m 3 .d, and the growth rate of sulfur autotrophic microorganisms in the moving bed is slow, which is not conducive to improving the denitrification efficiency. When the powder is added at a ratio of 60% of the mass of the sulfur autotrophic denitrification granular filter material, the water flow resistance in the mixed moving bed body 1 increases significantly, which can easily cause pipe gushing in the filter bed and there is a risk of bed overturning. Therefore, the mass of the powder added in the present invention is 10%-50% of the mass of the sulfur autotrophic denitrification granular filter material, and the optimal ratio range of the added powder is: the added mass of the powder is 30-40% of the mass of the sulfur autotrophic denitrification granular filter material.

[0061] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements may be made without departing from the inventive concept of the present invention, which all fall within the protection scope of the present invention.

Claims

1. A sulfur autotrophic denitrification mixed state moving bed, characterized in that: The invention comprises a mixed-state moving bed, a cylinder, a bracket, a water distribution device, an air stripping system, a fiber filter layer, a water inlet pipe and a water outlet pipe, wherein the cylinder, the bracket, the air stripping system and the water distribution device are all located in the mixed-state moving bed, the bracket is detachably mounted in the mixed-state moving bed, the cylinder is detachably mounted on the bracket, the air stripping system comprises an air inlet pipe, an air stripping pipe and a pressure relief cone plate, the air stripping pipe is vertically arranged at the center of the cylinder, the air stripping pipe is provided with an inlet end and an outlet end, the air inlet pipe passes through the side wall of the mixed-state moving bed and extends into the inlet end, the pressure relief cone plate is sleeved on the air stripping pipe The outer side of the lifting pipe and is located above the inlet end, the water distribution device is in the middle of the mixed-state moving bed, is sleeved on the outer side of the gas lifting pipe, and is above the pressure relief cone plate, the fiber filter layer is sleeved on the outer side of the cylinder, is located above the bracket, and is filled between the cylinder and the mixed-state moving bed, sulfur autotrophic denitrification granular filter material is placed in the cylinder and the mixed-state moving bed, the gas lifting pipe, the pressure relief cone plate and the water distribution device are surrounded by the sulfur autotrophic denitrification granular filter material, 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-state moving bed.

2. The sulfur autotrophic denitrification mixed-state moving bed according to claim 1, characterized in that: It also 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 bracket, and its outer periphery abuts against the side wall of the mixed-state 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-state moving bed, extends into the cylinder, and is located between the outlet end and the sulfur autotrophic denitrification granular filter material.

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

4. The sulfur autotrophic denitrification mixed-state moving bed according to claim 2, characterized in that: The water distribution device is provided with a water distribution port, the fiber filter layer is formed by stacking and filling biological rope fillers, and its thickness is 20 to 30 cm, the pore size of the metal mesh is 5x5mm to 10x10mm, the wire diameter is 1mm, the top angle of the pressure relief cone plate is 45 to 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.

5. The sulfur autotrophic denitrification mixed-state moving bed according to claim 2, characterized in that: It also includes a sedimentation and mud discharge device, which includes a radial flow sedimentation tank, a water inlet center cylinder, a mud discharge pipe, a mud discharge valve, a second valve and a third valve. The gas lift reflux circulation pipe is provided with a first valve front pipe, a first valve and a first valve rear pipe which are 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 mud discharge valve is connected to the bottom of the radial flow sedimentation tank, and the other end is connected to the mud discharge pipe.

6. A sulfur autotrophic denitrification method using a sulfur autotrophic denitrification mixed-state moving bed according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step a, adding sulfur autotrophic denitrification granular filter material and powder to prevent the sulfur autotrophic denitrification granular filter material from entering the air stripping pipe, the mass of the powder being 10% to 50% of the weight of the sulfur autotrophic denitrification granular filter material; Step b, introducing nitrate nitrogen wastewater into the water distribution device to form water flows in two directions, upward and downward, and entering the mixed moving bed body, the powder meets the nitrate nitrogen wastewater to form a slurry, and the pores between the sulfur autotrophic denitrification granular filter materials are filled with slurry, microbubbles, water and sulfur autotrophic microorganisms to form a mixed filter bed of sulfur autotrophic denitrification granular filter materials, slurry and sulfur autotrophic microorganisms, wherein the nitrate nitrogen content in the nitrate nitrogen wastewater is 50-300 mg / L, and the pH value is 8.5-11; Step c, introducing compressed air into the air lift pipe to circulate the sulfur autotrophic denitrification granular filter material, slurry, and sulfur autotrophic microorganisms from the bottom of the mixed filter bed-the top of the mixed filter bed-the bottom of the mixed filter bed, and perform sulfur autotrophic mixed denitrification treatment on the nitrate nitrogen wastewater; Step d, open the first valve, close the second valve and the third valve, and the liquid at the top of the cylinder is transported to the bottom of the mixed filter bed through the gas lift reflux circulation pipe for reflux and is sucked into the gas lift pipe again for circulation.

7. A sulfur autotrophic denitrification method according to claim 6, characterized in that: It also includes step e, when the water inlet pressure is greater than 50KPa, closing the first valve, opening the second valve and the third valve, and performing mud discharge treatment. After the mud discharge treatment is completed, opening the first valve, closing the second valve and the third valve, and resetting.

8. The sulfur autotrophic denitrification method according to claim 6, characterized in that: The particle size of the sulfur autotrophic denitrification granular filter material is 3 to 6 mm.

9. The sulfur autotrophic denitrification method according to claim 6, characterized in that: The powder material includes sulfur powder and limestone powder, and the mass ratio of the sulfur powder to the limestone powder is 7:

3.

10. A sulfur autotrophic denitrification method according to claim 9, characterized in that: The particle size of the sulfur powder is 20 μm to 200 μm, and the particle size of the limestone powder is 20 μm to 200 μm.

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