Fluidized bed reactor and method for sulfur autotrophic denitrification and phosphorus removal

Abstract

The application discloses a fluidized bed reaction device and method for sulfur autotrophic denitrification and phosphorus removal, and relates to the technical field of sewage treatment. The bottom of a cylinder body is connected with a water inlet pipe and a water outlet pipe, and the bottom of the side wall and the top of the side wall are respectively connected with the water inlet pipe and the water outlet pipe. The inside of the cylinder body is divided into a clear water area, a sedimentation area and a fluidization area from top to bottom by filter layer structures and water distributors arranged in the cross section, and a rake mechanism. The cylinder body is also provided with a circulation pipeline connected with the water distributor and the bottom of the clear water area. The denitrification microorganisms, sulfur autotrophic electron donors and flocculent particles in the fluidization area are kept in a suspended state, which helps to improve the electron transfer efficiency between the microorganisms and the solid sulfur and the denitrification reaction rate. The filter layer structures use the upward flow of liquid to filter the suspended matters in the liquid at the bottom of the filter layer structures to form sinking filter cakes, which avoids the loss of the denitrification microorganisms and the sulfur autotrophic electron donors, and ensures the turbidity of the effluent, the sludge concentration in the fluidization area and the denitrification efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a fluidized bed reaction device and method for advanced denitrification and dephosphorization of sewage in a sewage treatment plant. BACKGROUND

[0002] Nitrogen and phosphorus are the main elements leading to water eutrophication. The phosphorus in domestic sewage mainly relies on microbial treatment, but the total phosphorus concentration of the secondary treated effluent is stable at about 0.5-1 mg / L, which is difficult to meet the higher requirement of 0.2 mg / mL. The advanced dephosphorization of sewage generally adopts the method of adding iron salt and aluminum salt to sewage to form iron phosphate and aluminum phosphate compound precipitates, and then removing the iron phosphate and aluminum phosphate compound precipitates in the sewage by sand filtration, coagulation and magnetic separation.

[0003] In the prior art, the nitrogen removal in domestic sewage generally adopts the nitrification-heterotrophic denitrification process technology, which utilizes the aerobic biological metabolism process to convert the organic nitrogen and ammonia nitrogen in water into nitrate nitrogen, and then returns the sewage to the anoxic tank to convert the nitrate nitrogen into nitrogen gas by using the organic matter in the sewage as an electron donor through heterotrophic denitrifying microorganisms. The reflux denitrification technology also encounters some obstacles to meet the increasingly stringent total nitrogen water quality standard of drainage: first, a very high reflux ratio is needed to make the total nitrogen meet the discharge standard, resulting in excessive water treatment energy consumption and economic inefficiency; second, the carbon-nitrogen ratio of domestic sewage is generally too low to meet the demand of heterotrophic denitrification for organic carbon.

[0004] In order to further improve the nitrogen removal effect of sewage, an anaerobic biological filter is added after the secondary sedimentation tank and organic carbon is added to the biological filter to rely on heterotrophic denitrifying bacteria for denitrification, which is a common treatment method at present. However, the addition of sodium acetate and other reagents leads to high denitrification cost, and the measurement control in the addition process is not in place, which also leads to high COD in the effluent and secondary pollution problems.

[0005] In order to make up for the lack of heterotrophic denitrification, adapt to the demand of water treatment deep denitrification, in recent years, sulfur autotrophic denitrification technology as a representative of autotrophic denitrification technology has been rapidly developed. Sulfur autotrophic denitrification is a kind of facultative anaerobic microorganism such as denitrifying sulfur bacteria which uses inorganic carbon as carbon source to complete the anabolism, at the same time, uses sulfur and reduced sulfur compounds such as thiosulfate, sulfite and sulfide as electron donor to reduce nitrate to nitrogen. Among them, sulfur and iron sulfide as electron donor for denitrification is the mainstream direction of development. Sulfur autotrophic denitrification has the advantages of rich and cheap sulfur resources, less sludge production and low treatment cost. In the process of autotrophic denitrification denitrification with sulfur as electron donor, water acidification will occur, and limestone and other carbonates are usually used as pH stabilizing medium. The existing sulfur-limestone autotrophic denitrification system is to mix limestone and elemental sulfur particles in a certain proportion as filler, and then put into the reaction filter column for wastewater treatment. The limestone neutralizes the acid produced by reducing sulfur oxidation, so as to buffer and stabilize the pH of the system.

[0006] However, in the prior art, the sulfur autotrophic denitrification deep denitrification and phosphorus removal technology has the following outstanding problems:

[0007] First, the problem of granulation of sulfur autotrophic material. The current sulfur autotrophic denitrification technology borrows the quartz sand deep bed filter process, which first needs to granulate the sulfur autotrophic denitrification material to get 2-6mm particles, and then fill them into the anaerobic denitrification filter. The material in the form of sulfur autotrophic composite filter material generally adopts melting granulation method, which requires special sulfur composite and melting granulation equipment. Especially for high water content sulfur raw materials such as sulfur paste, melting granulation first needs to be dried and dehydrated, or first steam heated in a molten sulfur tank to separate sulfur and water. The granulation process inevitably greatly increases the processing cost of sulfur autotrophic material.

[0008] Second, the problem of clogging and backwashing of autotrophic denitrification denitrification filter. During the operation of sulfur autotrophic denitrification filter material in the filter, the growth of biofilm, the interception of suspended solids in water, the disintegration and pulverization of sulfur autotrophic denitrification filter material, and the accumulation of fine particles in the filter material will cause the clogging of the interstitial space between the filter particles. When the water flow rate is reduced to a certain extent, the accumulated fine particles in the interstitial space between the filter particles need to be removed by backwashing. However, the backwashing process not only washes out the fine particles that cause clogging, but also causes the detachment of biofilm. The autotrophic bacteria have a long growth cycle, and the biofilm recovery is slow, which requires a certain period of time and affects the water quality during the biofilm recovery period. In addition, the particle density and strength of sulfur and its composite materials are low, and there is a large difference between the density and strength of carbonate minerals. Backwashing can easily cause the abrasion and loss of sulfur particles, and also cause the separation of sulfur particles and carbonate particles.

[0009] Third, the problem of nitrogen driving of autotrophic denitrification denitrification filter. The nitrogen generated in the process of sulfur autotrophic denitrification is adsorbed on the surface of sulfur autotrophic particle filter material, and the bubbles difficult to discharge accumulate in the filter layer to cause gas blockage, which affects the operation of the filter. Regular nitrogen driving is needed.

[0010] Fourth, the existing fluidized reactor is difficult to completely separate the suspended solids by sedimentation, not only resulting in the loss of autotrophic microorganisms, reducing the concentration of autotrophic microorganisms in the fluidized bed reactor, but also resulting in the loss of fine particle sulfur autotrophic material, which is not suitable for the denitrification of sulfur paste and other slurry fine particle sulfur autotrophic materials. SUMMARY

[0011] The present application is to avoid the deficiencies of the prior art, and provides the invention name.

[0012] The present application is to avoid the deficiencies of the prior art, and provides the invention name.

[0013] A fluidized bed reactor for sulfur autotrophic denitrification and phosphorus removal is provided, which comprises a cylinder having an internal cavity, an inlet pipe and an outlet pipe communicated with the bottom of the cylinder and the top of the side wall of the cylinder respectively, a filter layer structure and a water distributor arranged in the cavity in sequence from top to bottom to form a clear water zone, a settling zone and a fluidization zone, and a rake mechanism.

[0014] A circulating pipeline is further provided, which is communicated with the water distributor and the bottom of the clear water zone respectively, and a water pump is arranged on the circulating pipeline.

[0015] Preferably, a central pipe is further included.

[0016] The central pipe is arranged through the center of the filter layer structure and extends upward above the clear water zone, and the central pipe is integrally connected with the filter layer structure.

[0017] Preferably, the water distributor comprises a circulating water inlet, a circular pipe and a water distribution branch pipe.

[0018] The circular pipe has a ring-shaped structure, each water distribution branch pipe is arranged in the ring-shaped structure of the circular pipe, and the two ends of each water distribution branch pipe are communicated with the circular pipe; the circular pipe is provided with the circulating water inlet communicated with the circulating pipeline, and the top and both sides of each water distribution branch pipe are provided with holes.

[0019] Preferably, a sludge discharge pipe, a backwashing discharge pipe and a backwashing water inlet pipe are further included, the water distributor is further provided with a backwashing water inlet opposite to the circulating water inlet, and the backwashing water inlet is communicated with the backwashing water inlet pipe.

[0020] The sludge discharge pipe is arranged at the side wall bottom of the cylinder opposite to the inlet pipe, and the backwashing discharge pipe is communicated with the outlet pipe and connected to the side wall top of the cylinder in parallel.

[0021] Preferably, the stirring mechanism comprises a stirring drive, a stirring shaft, stirring blades and a limiting end;

[0022] The stirring shaft extends through the central pipe from top to bottom to the bottom of the fluidization zone, with its top end fixedly connected to the output shaft of the fixedly installed stirring drive, and its bottom end fixedly connected to the stirring blades; a gap is provided between the stirring shaft and the central pipe;

[0023] The bottom of the stirring blades is provided with a downwardly protruding limiting end at the extension line of the axis of the stirring shaft, and a limiting cylinder corresponding to the limiting end is formed in the inner bottom of the cylinder;

[0024] The limiting end is inserted into the limiting cylinder to limit the lower end of the stirring shaft.

[0025] Preferably, the rake mechanism comprises rake teeth, rake rods, a rotating beam, end rollers and a shaft holder;

[0026] The top end of the rake rod is fixedly connected to the rotating beam, and the bottom end is fixedly provided with rake teeth that extend into the filter material;

[0027] The stirring shaft penetrates through the rotating beam, and a rotating pair is formed between the two to allow relative rotation of the two around the axis of the stirring shaft;

[0028] One end roller is rotatably installed at each end of the rotating beam, and the end roller is arranged on the top of the upper end surface of the cylinder, with the outer side being outwardly protruding in a limiting direction structure; the limiting direction structure is clamped on the outer side of the cylinder, and together with the stirring shaft, limits the relative position of the rotating beam and the end roller to the cylinder;

[0029] The outer ring and the inner ring of the shaft holder are fixedly installed with the rotating beam and the stirring shaft respectively, and when the shaft holder is clamped, the outer ring and the inner ring are locked to limit the relative rotation of the stirring shaft and the rotating beam.

[0030] Preferably, a baffle is further included;

[0031] The top of the central pipe is provided with a baffle that is shielded above the central pipe and has a gap between the top end of the central pipe.

[0032] Preferably, the filter layer structure comprises a support structure, a filter layer and the filter material;

[0033] The filter layer is a warehouse structure with a net-shaped bottom plate, and the filter material is filled in the filter layer;

[0034] The support structure is a triangular rib plate fixedly installed at the bottom of the filter layer, and the support structure is fixedly installed with the cylinder to support the filter layer.

[0035] Preferably, the cylinder is provided with an overflow weir groove above the filter layer structure and fixedly installed with the cylinder, and the outlet pipe is communicated with the clear water zone through the overflow weir groove;

[0036] Further comprising a dosing pipe; one end of the circulating pipeline, the dosing pipe and the inlet pipe are connected in parallel and fixed to the bottom of the side wall of the cylinder, and communicated with the fluidization zone.

[0037] A fluidized bed reaction method for sulfur autotrophic denitrification and phosphorus removal, using the above-mentioned fluidized bed reaction device for sulfur autotrophic denitrification and phosphorus removal to carry out advanced denitrification and phosphorus removal treatment of wastewater, comprising the following steps:

[0038] Firstly, powdered, slurry, and paste autotrophic denitrification and phosphorus removal agents are mixed to form a mass concentration of 0.5-10% autotrophic denitrification and phosphorus removal suspension, which is stored in a dosing barrel, and continuously stirred to keep the autotrophic denitrification and phosphorus removal suspension stable and prevent particle deposition;

[0039] Secondly, 0.1-10% of the treated sludge obtained from a domestic wastewater treatment plant is added to the cylinder as a source of microbial inoculum;

[0040] Thirdly, the valve of the inlet pipe is controlled to open, and the autotrophic denitrification and phosphorus removal agent suspension obtained in the first step is metered and continuously or intermittently added to the inlet pipe of the reaction device through the dosing pipe according to the equivalent ratio of nitrate nitrogen to autotrophic electron donor in water of 1:1~1.5, mixed with wastewater, and then enters the denitrification and phosphorus removal reactor, and the metered flow rate is controlled according to the preset hydraulic retention time;

[0041] Subsequently, the stirring drive machine and the water pump are started; the stirring drive machine drives the stirring blades to rotate through the stirring shaft, and the water pump drives the circulation flow of the mixed liquid, so that the autotrophic denitrification and phosphorus removal agent and the microorganisms containing autotrophic denitrifying bacteria are kept in a suspended state in the fluidization zone, the denitrifying microorganisms in the inoculated microorganisms convert the nitrate nitrogen in the mixed liquid into nitrogen gas using the electron donor, which is discharged to the outside of the cylinder through the central pipe, at the same time, the biological mineralization converts the dissolved phosphate into solid iron phosphate and calcium phosphate precipitates;

[0042] Fourthly, the upward suspension in the fluidization zone is separated into sinking particles and clarified liquid in the settling zone, the clarified liquid passes through the clear water generated by the filter layer, during the process of passing through the filter layer, a microbial membrane is formed on the surface of the filter material particles, and the fine particles including free microorganisms in the clarified liquid are intercepted by the filter layer, the clear water passing through the filter layer, i.e. the treated wastewater, is discharged to the outside of the cylinder in turn through the overflow weir groove and the outlet pipe;

[0043] The fifth step is to gradually increase the opening degree of the valve at the water inlet pipe in the initial stage of starting the fluidized bed reaction device, so as to gradually increase the liquid inlet flow and shorten the hydraulic retention time to the stable operation of the fluidized bed reaction device.

[0044] The sixth step is that, in the process of stable operation of the fluidized bed reaction device, if the liquid level in the central pipe rises to a preset warning liquid level, the valves at the water inlet pipe, the dosing pipe and the water outlet pipe are closed, the water pump is stopped, the backwashing valve at the water inlet pipe is opened, the backwashing valve at the discharge pipe is opened, and the backwashing water pump is started, and at the same time, the rotating speed of the stirring shaft is reduced.

[0045] At this time, the backwashing water flows into the water distributor through the backwashing water inlet pipe under the action of the backwashing water pump, and then is distributed to each water distribution branch pipe through the circular pipe, and then flows out upward through each hole of each water distribution branch pipe to backwash the filter layer, and then flows upward to overflow the weir groove to the backwashing discharge pipe for overflow discharge.

[0046] At the same time, the shaft holder of the rake mechanism holds the stirring shaft, drives the rake teeth to rotate around the axis of the stirring shaft through the rotating beam and the rake rod, and stirs the filter material particles, so that the air bubbles accumulated between the filter material particles are discharged, the filter material particles are re-stacked, the gaps between the filter material particles are re-created, and the permeability of the filter layer is restored.

[0047] After the rake teeth rotate around the axis of the stirring shaft, the liquid level in the central pipe is reduced to within cm of the liquid level outside the central pipe, and the filtering function of the filter layer is completely restored.

[0048] Then, the backwashing water pump is stopped, the valves at the backwashing water inlet pipe and the backwashing discharge pipe are closed, the shaft holder is released, the valves at the water inlet pipe, the dosing pipe and the water outlet pipe are opened, and the water pump is started to continue the normal treatment of the wastewater.

[0049] The present application provides a fluidized bed reaction device and method for sulfur autotrophic denitrification and phosphorus removal, which can use a suspension prepared from powdery, semi-solid, slurry and paste sulfur-rich raw materials as an electron donor for wastewater denitrification and phosphorus removal treatment, realizes direct addition of a low-cost sulfur electron donor with high water content to a water treatment reactor for denitrification and phosphorus removal treatment, and solves the problem of interception of microorganisms and sulfur electron donor particles in the fluidized bed reactor, and has the following beneficial effects:

[0050] 1、The water distribution pipe and filter layer structure of the present application naturally divide the cavity of the cylinder into clear water zone, settling zone and clear water zone, and the denitrification microorganism, sulfur autotrophic electron donor and its flocculation particulate matter in the fluidization zone are kept in suspended state, which helps to improve the electron transfer efficiency between microorganism-solid reduced sulfur and the denitrification reaction rate; most of the suspended matter in the settling zone settles into the fluidization zone, which reduces the load of suspended matter intercepted by the filter layer and the plugging effect, and prolongs the backwashing period; the filter layer structure uses the upward flow of liquid to filter the suspended matter in the liquid, and forms filter cake at the bottom of the filter layer structure, which settles to the fluidization zone under the action of gravity, avoiding the loss of denitrification microorganism and sulfur autotrophic electron donor, and ensuring the turbidity of effluent and the sludge concentration and denitrification efficiency in the fluidization zone.

[0051] 2、The filter layer structure of the present application is filled with low-density porous medium filter material, which reduces the bulk density, support structure load and backwashing intensity; under the same particle size, the lower the density of filter material particles, the lower the backwashing intensity required for filter layer expansion, the shorter the time for washing and removing suspended matter intercepted in the filter layer, and the lower the water consumption.

[0052] 3、The rake mechanism of the present application rakes the filter material through push-grinding type circumferential motion, promotes the discharge of bubbles accumulated in the filter material layer, realizes the nitrogen removal of the filter material in the filter layer structure, loosens the filter material layer, re-creates inter-particle space, reduces the plugging effect of the filter layer, prolongs the backwashing period, and improves the denitrification treatment effect.

[0053] 4、The filter material in the filter layer structure of the present application is attached with autotrophic and heterotrophic denitrification microbial membrane, and the sulfur autotrophic electron donor particles and microorganisms are intercepted between the filter material particles, and complex microbial metabolism occurs in the filter layer structure, which plays a role in fixed filter bed autotrophic and heterotrophic collaborative deep denitrification.

[0054] 5、The setting of the central pipe avoids the formation of a joint between the filter structure and the filter structure when the stirring shaft penetrates through the filter structure, which causes the direct short flow of the rising water flow at the joint, forces the water flow to penetrate through the filter material layer, and ensures the effective action of the filter material structure; at the same time, the gap between the stirring shaft and the central pipe provides an escape channel for the nitrogen gas generated by the denitrification; in addition, the height of the top of the central pipe is higher than the height of the filter layer structure, and the height difference uses air pressure to compensate for the hydraulic loss of the normal filtration water flow of the filter layer structure, which helps to prolong the backwashing period, and further avoids the destruction of the stability of the anaerobic denitrification system by backwashing, and improves the stability and efficiency of the deep treatment of wastewater.

[0055] 6、The stirring mechanism of the present application not only better realizes the suspension of microorganisms and sulfur autotrophic electron donor particles in the fluidization zone, but also prevents the long-term deposition of relatively coarse sulfur autotrophic electron donor particles at the bottom of the suspended zone, which affects the inlet and blocks the sewage pipe opening, and also has the function of strengthening the grinding and refinement of coarse sulfur autotrophic electron donor particles.

[0056] 7. During the backwashing process of the reactor, the baffle of the present invention reflects the water jet sprayed from the top opening of the central tube downwards, uses the reflected water jet to wash the filter media layer, and promotes the outflow of suspended matter that has been washed away from the filter media, which is beneficial to improving the backwashing effect and increasing the backwashing efficiency. Attached Figure Description

[0057] Fig. 1 This is a schematic diagram of the main structure of the present invention;

[0058] Fig. 2 This is a top view of the water distributor of the present invention;

[0059] Fig. 3 This is a cross-sectional structural schematic diagram of the rake mechanism of the present invention.

[0060] In the picture:

[0061] 1. Filter cylinder; 1-1. Inlet pipe; 1-2. Outlet pipe; 1-3. Sludge discharge pipe; 1-4. Backwash inlet pipe; 1-5. Backwash discharge pipe; 1-6. Chemical dosing pipe; 1-7. Circulation pipeline; 1-8. Water pump; 1-9. Limiting cylinder; 1-10. Overflow weir; 1-11. Baffle; 2. Fluidization zone; 3. Settling zone; 4. Filter layer structure; 4-1. Support structure; 4-2. Filter layer; 4-3. Filter media; 5. 6. Rake mechanism, 6-1. Rake teeth, 6-2. Rake rod, 6-3. Rotating beam, 6-4. End roller, 6-5. Shaft clamp; 7. Water distributor, 7-1. Backwash inlet, 7-2. Circulation inlet, 7-3. Water distribution branch pipe, 7-4. Circular pipe, 7-5. Hole; 8. Stirring mechanism, 8-1. Stirring drive motor, 8-2. Stirring shaft, 8-3. Stirring blades, 8-4. Limiting end, 9. Central pipe. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] A fluidized bed reactor for sulfur autotrophic denitrification and phosphorus removal, such as Figs. 1-3 As shown, its structural relationship is as follows: it includes a cylindrical body 1 with an internal cavity, and the bottom to the bottom of the side wall and the top of the side wall of the cylindrical body 1 are respectively connected to an inlet pipe 1-1 and an outlet pipe 1-2. It includes a clear water zone 5, a sedimentation zone 3 and a fluidization zone 2 formed by a filter layer structure 4 covering the cross-section and a water distributor 7 arranged sequentially from top to bottom in the cavity, as well as a rake mechanism 6.

[0064] A circulating pipeline 1-7 is also provided, which is in communication with the water distributor 7 and the bottom of the clear water zone 5 respectively, and a water pump 1-8 is arranged on the circulating pipeline 1-7 to serve as a power source for the liquid flow, microbial floc and electronic donor particle suspension;

[0065] The filter layer structure 4 is filled with low-density porous medium filter material 4-3, and the rake mechanism 6 is used for raking the filter material.

[0066] In actual arrangement, the water inlet pipe 1-1 and the water outlet pipe 1-2 can be provided with a water inlet pipe valve and a water outlet pipe valve according to actual needs.

[0067] The filter material 4-3 is a porous granular material with a density of 1.1-2.2 mm / cm 3 and a particle size of 1-10 mm, including but not limited to high-density expanded perlite, water-quenched steel slag, granular activated carbon, low-density ceramsite, zeolite rock particles, porous ceramics, foamed basalt, and aerated concrete particles.

[0068] Preferably, the filter material 4-3 can be prepared by the following method: the diatom shale is crushed, rolled, and sieved to obtain subangular particles with a particle size of 3-5 mm, which are calcined at 500-1000°C to obtain porous, water-resistant granular filter material 4-3 with a density of 1.2-1.5 g / cm 3 .

[0069] Preferably, the center pipe 9 is also included.

[0070] A center pipe 9 is arranged through the center of the filter layer structure 4 and is in communication with the sedimentation zone 3 and extends upward above the clear water zone 5, and the center pipe 9 is integrally connected with the filter layer structure 4.

[0071] The center pipe 9 is used for discharging nitrogen generated by denitrification.

[0072] Preferably, the water distributor 7 includes a circulating water inlet 7-2, a circular pipe 7-4, and water distribution branch pipes 7-3.

[0073] The circular pipe 7-4 has a ring-shaped structure, each water distribution branch pipe 7-3 is arranged in the ring-shaped structure of the circular pipe 7-4, and the two ends are in communication with the circular pipe 7-4; the circular pipe 7-4 is provided with a circulating water inlet 7-2 in communication with the circulating pipeline 1-7, and the top and both sides of the water distribution branch pipe 7-3 are densely provided with holes 7-5.

[0074] In actual arrangement, the diameter of the hole 7-5 can be 1-10 mm, and the distance between adjacent holes can be 50-200 mm.

[0075] Preferably, the sludge discharge pipe 1-3, the backwash discharge pipe 1-5 and the backwash water inlet pipe 1-4 are further included, and the water distributor 7 is further provided with a backwash water inlet 7-1 opposite the circulation water inlet 7-2, which is in communication with the backwash water inlet pipe 1-4;

[0076] The side wall of the barrel 1 is provided with the sludge discharge pipe 1-3 at the bottom opposite the water inlet pipe 1-1, and the backwash discharge pipe 1-5 is in parallel communication with the water outlet pipe 1-2 and extends to the top of the side wall of the barrel 1.

[0077] Preferably, the stirring mechanism 8 is further included, which comprises a stirring drive 8-1, a stirring shaft 8-2, stirring blades 8-3 and a limiting end 8-4;

[0078] The stirring shaft 8-2 extends through the central pipe 9 from top to bottom to the bottom of the fluidization zone 2, the top end is fixedly connected with the output shaft of the fixedly installed stirring drive 8-1, and the bottom end is fixedly connected with the stirring blades 8-3; a gap is left between the stirring shaft 8-2 and the central pipe 9;

[0079] In actual installation, the inner diameter of the central pipe 9 is preferably 2-10 cm larger than the outer diameter of the stirring shaft 8-2;

[0080] The bottom of the stirring blades 8-3 is provided with a lower limiting end 8-4 at the extension line of the axis of the stirring shaft 8-2, and the inner bottom of the barrel 1 is correspondingly provided with a limiting cylinder 1-9 matched with the limiting end 8-4;

[0081] The limiting end 8-4 is inserted into the limiting cylinder 1-9 for limiting the lower end of the stirring shaft 8-2.

[0082] Preferably, the rake mechanism 6 comprises rake teeth 6-1, rake rods 6-2, a rotating beam 6-3, end rollers 6-4 and a shaft holder 6-5;

[0083] The top end of the rake rod 6-2 is fixedly connected with the rotating beam 6-3, and the bottom end is fixedly provided with the rake teeth 6-1 which are inserted into the filter material 4-3;

[0084] The stirring shaft 8-2 penetrates through the rotating beam 6-3, and a rotating pair is formed between them to allow relative rotation around the axis of the stirring shaft 8-2;

[0085] One end roller 6-4 is rotatably installed at each end of the rotating beam 6-3, and the end roller 6-4 is arranged on the top of the upper end surface of the barrel 1, and the outer side thereof is provided with a limiting guide structure which protrudes outward in the radial direction; the limiting guide structure is clamped on the outer side of the barrel 1, and the stirring shaft 8-2 limits the relative position of the rotating beam 6-3 and the end roller 6-4 with the barrel 1;

[0086] The outer ring and the inner ring of the shaft holder 6-5 are fixedly installed with the rotating beam 6-3 and the stirring shaft 8-2 respectively, and when the shaft holder 6-5 is clamped, the outer ring and the inner ring are locked to limit the relative rotation of the stirring shaft 8-2 and the rotating beam 6-3.

[0087] In actual installation, the shaft holder 6-5 can be an electromagnetic shaft holder.

[0088] Preferably, the baffle 1-11 is further included.

[0089] The top opening of the central pipe 9 is provided with the baffle 1-11 which is shielded above the central pipe 9 and has a gap between the top end of the central pipe 9.

[0090] In actual installation, the baffle 1-11 can be a conical cylindrical structure with the diameter increasing from top to bottom.

[0091] When the reactor is provided with a stirring mechanism, the baffle 1-11 can prevent the backwashing water from being directly sprayed upward from the top opening of the central pipe 9 to flow out, so as to prevent the stirring drive 81 from being wet. At this time, the baffle 1-11 can also be fixedly installed on the stirring shaft 82.

[0092] Preferably, the filter layer structure 4 includes a support structure 4-1, a filter layer 4-2 and filter material 4-3.

[0093] The filter layer 4-2 is a warehouse structure with a net-shaped bottom plate, and the filter material 4-3 is filled in the filter layer 4-2.

[0094] The filter layer 4-2 is fixedly installed with a triangular rib plate-shaped support structure 4-1 at the bottom, and the support structure 4-1 is fixedly installed with the cylinder 1 for supporting the filter layer 4-2.

[0095] In actual installation, the thickness of the filter material 4-3 is preferably 20-50 cm, and the support structure 41 can be made of steel material.

[0096] Preferably, the cylinder 1 is provided above the filter layer structure 4 with an overflow outlet weir groove 1-10 fixedly installed with the cylinder 1, and the outlet pipe 1-2 is communicated with the clean water area 5 through the overflow outlet weir groove 1-10.

[0097] When the outlet pipe 1-2 is communicated with the clean water area 5 through the overflow outlet weir groove 1-10, the backwashing discharge pipe 1-5 can also be arranged in parallel with the outlet pipe 1-2 and communicated with the clean water area 5 through the overflow outlet weir groove 1-10.

[0098] The dosing pipe 1-6 is further included; one end of the circulating pipeline 1-7, the dosing pipe 1-6 and the water inlet pipe 1-1 are fixedly connected in parallel to the side wall of the cylinder 1 at the bottom and communicated with the fluidized area 2.

[0099] A fluidized bed reaction method for sulfur autotrophic denitrification and phosphorus removal, using the above-mentioned sulfur autotrophic denitrification and phosphorus removal fluidized bed reaction device for advanced denitrification and phosphorus removal treatment of wastewater, comprising the following steps:

[0100] Firstly, the autotrophic denitrification and phosphorus removal agent in powder, slurry, paste form is prepared into a mass concentration of 0.5-10% autotrophic denitrification and phosphorus removal suspension and stored in the dosing barrel tank, and continuous stirring is carried out to keep the autotrophic denitrification and phosphorus removal suspension stable and prevent the particles from settling;

[0101] The sulfur autotrophic denitrification and phosphorus removal agent can be in powder, semi-solid, slurry, paste form, and the main components are sulfur, soluble sulfide and polysulfide, iron-manganese sulfide, carbonate mineral;

[0102] Secondly, 0.1-10% of the treated sludge obtained from the domestic wastewater treatment plant is added to the cylinder 1 as a source of microbial strains;

[0103] Thirdly, the valve of the water inlet pipe 1-1 is controlled to open, and the sulfur autotrophic denitrification and phosphorus removal agent suspension obtained in the first step is metered and continuously or intermittently added to the water inlet pipe 1-1 of the reaction device according to the equivalent ratio of nitrate nitrogen to autotrophic electron donor in water of 1:1~1.5, mixed with wastewater and then enters the denitrification and phosphorus removal reactor, and the metering flow is controlled according to the preset hydraulic retention time;

[0104] In actual operation, the hydraulic retention time can be preferably preset to 6h;

[0105] Subsequently, the stirring drive 8-1 and the water pump 1-8 are started; the stirring drive 8-1 drives the stirring blade 8-3 to rotate through the stirring shaft 8-2, and the water pump 1-8 drives the circulation flow of the mixed liquid, so that the autotrophic denitrification and phosphorus removal agent and the microorganisms containing autotrophic denitrifying bacteria are kept in a suspended state in the fluidization zone 2, the denitrifying microorganisms in the inoculated microorganisms convert the nitrate nitrogen in the mixed liquid into nitrogen gas using the electron donor, which is discharged to the outside of the cylinder 1 through the central pipe 9, and at the same time, the biological mineralization converts the dissolved phosphate into solid iron phosphate and calcium phosphate precipitates;

[0106] The ascending suspension in the fluidization zone is separated into sinking particles and clarified liquid in the settling zone 3, and the clarified liquid passes through the clear water generated by the filter layer 4-2, and in the process of passing through the filter layer 4-2, a microbial membrane is formed on the surface of the filter material particles, and the fine particles including free microorganisms in the clarified liquid are intercepted by the filter layer 4-2, and the clear water passing through the filter layer is the treated wastewater, which is discharged to the outside of the cylinder 1 in turn through the overflow weir tank 1-10 and the effluent pipe 1-2;

[0107] During the initial stage of the fluidized bed reactor, the opening of the valve at the inlet pipe 1-1 is gradually increased to increase the liquid flow rate and reduce the hydraulic retention time to a stable operation of the fluidized bed reactor.

[0108] In actual use, the initial stage preferably lasts for 3-10 days, and the hydraulic retention time is preferably reduced from 6 hours to 0.5 hour;

[0109] During the stable operation of the fluidized bed reactor, if the liquid level in the central pipe 9 rises to a preset warning liquid level,

[0110] At this time, the solid retention of the filter material in the filter layer 4-2 increases, the biological membrane thickens, and the porosity between the filter materials decreases, resulting in a decrease in the permeability of the filter layer 4-2, causing the water level in the central pipe 9 to rise;

[0111] The valves at the inlet pipe 1-1, the dosing pipe 1-6, and the outlet pipe 1-2 are closed, the water pump 1-8 is stopped, the valve at the backwashing inlet pipe 1-4 is opened, the valve at the backwashing discharge pipe 1-5 is opened, and the backwashing water pump is started. At the same time, the rotation speed of the stirring shaft is reduced.

[0112] At this time, the backwashing water flows into the water distributor 7 through the backwashing inlet 7-1 of the backwashing inlet pipe 1-4 under the action of the backwashing water pump, and then is distributed to each water distribution branch pipe 7-3 through the circular pipe 7-4. The water flows out of each hole 7-5 of each water distribution branch pipe 7-3 upward to backwash the filter layer 4-2, and then flows upward to overflow the overflow weir tank 1-10 to the backwashing discharge pipe 1-5.

[0113] At the same time, the shaft holder 6-5 of the rake mechanism 6 tightly holds the stirring shaft 8-2, and drives the rake teeth 6-1 to rotate around the axis of the stirring shaft 8-1 through the rotating beam 6-3 and the rake rod 6-2, so as to stir the filter material particles, discharge the air bubbles accumulated between the filter material particles, and re-accumulate the filter material particles to restore the porosity between the filter material particles and the permeability of the filter layer 4-2.

[0114] After the rake teeth 6-1 rotate around the axis of the stirring shaft 8-1 for 1-3 turns, the liquid level in the central pipe 9 is reduced to within 2 cm of the liquid level outside the central pipe 9, and the filtering function of the filter layer 4-2 is completely restored.

[0115] Then, the backwashing water pump is stopped, the valves at the backwashing inlet pipe 1-4 and the backwashing discharge pipe 1-5 are closed, the shaft holder 6-5 is released, the valves at the inlet pipe 1-1, the dosing pipe 1-6, and the outlet pipe 1-2 are opened, and the water pump 1-8 is started. The normal treatment of wastewater continues.

[0116] In actual setting, the warning liquid level height can be set at 1-2 cm from the top end of the central pipe 9, and the monitoring of the liquid level height can be realized by a liquid level indicator with automatic alarm function, such as QDY30A-B-G type immersion liquid level sensor of Shanghai Wuji Automation Equipment Co., Ltd. or LUSS-99305PD0DS type ultrasonic liquid level meter of Shandong Dongrun.

[0117] The opening and closing of each valve, the starting and stopping of the water pump 1-8, and the clamping and unclamping of the shaft holder 6-5 can be controlled by a control module, which can be preferably a Siemens 200 smartPLC, a Mitsubishi FX2N PLC or a Delta AS200 PLC. Embodiment

[0118] The fluidized bed reaction device for sulfur autotrophic denitrification and phosphorus removal is used for advanced denitrification and phosphorus removal treatment of sewage, including the following steps:

[0119] Firstly, the autotrophic denitrification and phosphorus removal agent in paste form is prepared into an autotrophic denitrification and phosphorus removal suspension with a mass concentration of 5% and stored in a dosing barrel tank, and continuously stirred to keep the autotrophic denitrification and phosphorus removal suspension stable and prevent the particles from precipitating;

[0120] The autotrophic denitrification and phosphorus removal agent contains 86% elemental sulfur, 7% nano-structured mineral material and 7% other components in dry basis;

[0121] Secondly, 3% of the residual sludge obtained from a domestic sewage treatment plant is added into the cylinder 1 as a source of microbial strains;

[0122] Thirdly, the valve of the water inlet pipe 1-1 is controlled to be opened, and the autotrophic denitrification and phosphorus removal agent suspension obtained in the first step is metered and continuously or intermittently added into the water inlet pipe 1-1 of the reaction device according to the equivalent ratio of nitrate nitrogen to autotrophic electron donor in water being 1:1.1 through the dosing pipe 1-6, mixed with the wastewater and then enters the denitrification and phosphorus removal reactor, and the metered flow rate is controlled according to the hydraulic retention time of 6 h;

[0123] Subsequently, the stirring driver 8-1 and the water pump 1-8 are started; the stirring driver 8-1 drives the stirring blades 8-3 to rotate through the stirring shaft 8-2, so that the stirring blades 8-3 slowly stir at a speed of 2-3 r / min, and at the same time, the water pump 1-8 drives the circulation of the mixed liquid, so that the autotrophic denitrification and phosphorus removal agent and the microorganisms containing autotrophic denitrifying bacteria are kept in a suspended state in the fluidization zone 2, and the sulfur autotrophic denitrifying microorganisms are directionally enriched and proliferated;

[0124] The denitrifying microorganisms in the inoculated microorganisms utilize the electron donor to convert the nitrate nitrogen in the mixed liquid into nitrogen gas which is discharged to the outside of the cylinder 1 through the central pipe 9, and at the same time, the biological mineralization converts the dissolved phosphate into solid iron phosphate and calcium phosphate precipitates;

[0125] The fourth step, the ascending suspension in the fluidization zone is separated into sinking particles and clarified liquid in the settling zone 3, the clarified liquid is clear water generated by the filter layer 4-2, in the process of passing through the filter layer 4-2, a microbial membrane is formed on the surface of the filter particles, the fine particles including free microorganisms in the clarified liquid are intercepted by the filter layer 4-2, the clear water passing through the filter layer is the treated wastewater, which is discharged to the outside of the cylinder 1 through the overflow weir tank 1-10 and the water outlet pipe 1-2 in turn;

[0126] The filter material in the above filter layer is selected from 2-6 mm irregular particles obtained by crushing and screening hard zeolite rock with a compressive strength of >100 kg / cm 2

[0127] In the initial stage of 10 days when the fluidized bed reactor starts to work, the opening of the valve at the inlet pipe 1-1 is gradually increased to gradually increase the liquid flow, and the hydraulic retention time is gradually shortened from 6 h to 0.5 h, so that the fluidized bed reactor is stably operated;

[0128] During the stable operation of the fluidized bed reactor, if the liquid level in the central pipe 9 rises to 2 cm from the top end, the liquid level indicator alarms, the control module controls the valves at the inlet pipe 1-1, the dosing pipe 1-6 and the water outlet pipe 1-2 to be closed, the water pump 1-8 is stopped, the valve at the backwashing inlet pipe 1-4 is opened, the valve at the backwashing discharge pipe 1-5 is opened, the backwashing water pump is started, and at the same time, the rotating speed of the stirring shaft is reduced;

[0129] At this time, the backwashing water flows into the water distributor 7 through the backwashing inlet 7-1 of the backwashing inlet pipe 1-4 under the action of the backwashing water pump, and then is distributed to each water distribution branch pipe 7-3 through the circular pipe 7-4, and then flows upward through each hole 7-5 of each water distribution branch pipe 7-3 to backwash the filter layer 4-2, and then flows upward to overflow through the overflow weir tank 1-10 to the backwashing discharge pipe 1-5;

[0130] At the same time, the shaft holder 6-5 of the rake mechanism 6 tightly holds the stirring shaft 8-2, drives the rake teeth 6-1 to rotate around the axis of the stirring shaft 8-1 through the rotating beam 6-3 and the rake rod 6-2, and rakes the filter particles, so that the bubbles accumulated between the filter particles are discharged, the filter particles are re-stacked, the gaps between the filter particles are re-created, and the permeability of the filter layer 4-2 is restored;

[0131] After the rake teeth 6-1 rotate 1-3 times around the axis of the stirring shaft 8-1, the liquid level in the central pipe 9 is reduced to within 2 cm of the liquid level outside the central pipe 9, and the filtering function of the filter layer 4-2 is completely restored;

[0132] ​Then, the backwash water pump is stopped, the valves at the backwash inlet pipe 1-4 and the backwash discharge pipe 1-5 are closed, the shaft holder 6-5 is released, the valves at the inlet pipe 1-1, the dosing pipe 1-6 and the outlet pipe 1-2 are opened, and the water pump 1-8 is started to continue the normal treatment of the wastewater.

[0133] It is to be noted that the relative terms such as first and second, and the like, are used herein only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between such entities or operations. Moreover, the terms "comprising", "including", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a..." does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0134] The above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A fluidized bed reactor for autotrophic denitrification and phosphorus removal by sulfur, comprising a cylinder (1) having a cavity inside, an inlet pipe (1-1) and an outlet pipe (1-2) being respectively communicated with the bottom of the cylinder (1) and the top of the sidewall, characterized in that: The filter layer structure (4) and the water distributor (7) are arranged in the container cavity in sequence from top to bottom to form a clear water area (5), a settling area (3) and a fluidization area (2) in sequence from top to bottom, and a rake mechanism (6); A circulation pipeline (1-7) is further arranged, and two ends of the circulation pipeline (1-7) are communicated with the water distributor (7) and the bottom of the cylinder (1), respectively; The filter layer structure (4) is filled with low-density porous medium filter material (4-3), and the rake mechanism (6) is used for raking the filter material; The center pipe (9) is further arranged; The center pipe (9) is arranged through the center of the filter layer structure (4) and is communicated with the settling area (3) and extends upward to above the clear water area (5) The stirring mechanism (8) is further arranged, and the stirring mechanism (8) comprises a stirring drive machine (8-1), a stirring shaft (8-2), stirring blades (8-3) and a limiting end (8-4); The stirring shaft (8-2) extends through the center pipe (9) from top to bottom to the bottom of the fluidization area (2), the top end is fixedly connected with the output shaft of the fixedly installed stirring drive machine (8-1), and the bottom end is fixedly connected with the stirring blades (8-3); a gap is arranged between the stirring shaft (8-2) and the center pipe (9); The bottom of the stirring blades (8-3) is provided with a lower limiting end (8-4) at the axis extension line of the stirring shaft (8-2), and a limiting cylinder (1-9) corresponding to the limiting end (8-4) is arranged in the bottom of the cylinder (1); The limiting end (8-4) is inserted into the limiting cylinder (1-9) to limit the lower end of the stirring shaft (8-2); The rake mechanism (6) comprises rake teeth (6-1), rake rods (6-2), rotating beams (6-3), end rollers (6-4) and a shaft holder (6-5); The top end of the rake rod (6-2) is fixedly connected with the rotating beam (6-3), and the bottom end is fixedly provided with the rake teeth (6-1) which are arranged in rows and extend into the filter material (4-3); The stirring shaft (8-2) penetrates the rotating beam (6-3), and a rotating pair is formed between the two to support the relative rotation of the two around the axis of the stirring shaft (8-2); The two ends of the rotating beam (6-3) are each rotatably installed with an end roller (6-4), the end roller (6-4) is arranged on the top of the upper end surface of the cylinder (1), the outer side of the end roller (6-4) is provided with a limiting edge structure which protrudes outward in the radial direction, the limiting edge structure is clamped on the outer side of the cylinder (1), and the relative position of the rotating beam (6-3) and the end roller (6-4) with the cylinder (1) is limited by the stirring shaft (8-2); The outer ring and the inner ring of the shaft holder (6-5) are fixedly installed with the rotating beam (6-3) and the stirring shaft (8-2), respectively, and when the shaft holder (6-5) is tightly held, the outer ring and the inner ring are locked to limit the relative rotation of the stirring shaft (8-2) and the rotating beam (6-3); Further comprising a baffle (1-11); The top opening of the center tube (9) is provided with a baffle (1-11) which is shielded above the center tube (9) and has a gap between the top end of the center tube (9).

2. The fluidized bed reactor for sulfur autotrophic denitrification and phosphorus removal according to claim 1, characterized in that: The water distributor (7) comprises a circulating water inlet (7-2), a circular tube (7-4) and a water distribution branch pipe (7-3); The circular tube (7-4) is in the form of a ring-shaped tubular structure, each water distribution branch pipe (7-3) is arranged in the ring-shaped structure of the circular tube (7-4), and the two ends are respectively communicated with the circular tube (7-4); the circular tube (7-4) is provided with the circulating water inlet (7-2) communicated with the circulating pipeline (1-7), and the top and both sides of the water distribution branch pipe (7-3) are densely provided with holes (7-5).

3. The fluidized bed reactor for sulfur autotrophic denitrification and phosphorus removal according to claim 2, characterized in that: Further comprising a sludge discharge pipe (1-3), a backwashing discharge pipe (1-5) and a backwashing water inlet pipe (1-4), the water distributor (7) is further provided with a backwashing water inlet (7-1) located on the opposite side of the circulating water inlet (7-2), and the backwashing water inlet (7-1) is communicated with the backwashing water inlet pipe (1-4); The side wall of the cylinder (1) is provided with a sludge discharge pipe (1-3) on the opposite side of the water inlet pipe (1-1), and the backwashing discharge pipe (1-5) is communicated with the water outlet pipe (1-2) and connected to the top of the side wall of the cylinder (1).

4. The fluidized bed reactor for sulfur autotrophic denitrification and phosphorous removal according to claim 1, characterized in that: The filter layer structure (4) comprises a support structure (4-1), a filter layer (4-2) and filter material (4-3); The filter layer (4-2) is a warehouse structure with a bottom plate in the form of a net, and the filter material (4-3) is filled in the filter layer (4-2); The filter layer (4-2) is provided with the triangular ribbed support structure (4-1) at the bottom, and the support structure (4-1) is fixed with the cylinder (1) for supporting the filter layer (4-2).

5. The fluidized bed reactor for sulfur autotrophic denitrification and phosphorus removal according to claim 1, characterized in that: The cylinder (1) is provided with an overflow outlet weir groove (1-10) above the filter layer structure (4) and fixed with the cylinder (1), and the water outlet pipe (1-2) is communicated with the clear water area (5) through the overflow outlet weir groove (1-10); Further comprising a dosing pipe (1-6), one end of the circulating pipeline (1-7), the dosing pipe (1-6) and the water inlet pipe (1-1) are connected and fixed to the bottom of the side wall of the cylinder (1) and communicated with the fluidized area (2).

6. A fluidized bed reaction method for sulfur autotrophic denitrification and phosphorus removal, using the fluidized bed reaction device for sulfur autotrophic denitrification and phosphorus removal according to any one of claims 1 to 5 for advanced denitrification and phosphorus removal treatment of sewage, characterized by, The method comprises the following steps: First, mix the autotrophic denitrification and phosphorus removal agent in powder, slurry or paste into an autotrophic denitrification and phosphorus removal suspension with a mass concentration of 0.5-10% and store it in a dosing barrel, continuously stir to keep the state of the autotrophic denitrification and phosphorus removal suspension stable and prevent the particles from settling; Second, add residual sludge with a volume of 0.1-10% obtained from a domestic sewage treatment plant into the cylinder (1) as a source of microbial strains; Third step, control the valve of inlet pipe (1-1) open, through dosing pipe (1-6) according to the equivalent ratio of nitrate nitrogen and autotrophic electron donor in water is 1:1~1.5, the first step obtained by the suspension of sulfur autotrophic denitrification and phosphorus removal agent, metering continuous addition or intermittent addition to the inlet pipe (1-1) of the reaction device, mixed with wastewater into the denitrification and phosphorus removal reactor, metering flow according to the preset hydraulic retention time control; Subsequently, start stirring drive machine (8-1) and water pump (1-8); The stirring drive machine (8-1) drives the stirring blade (8-3) to rotate through the stirring shaft (8-2), and the water pump (1-8) drives the circulating flow of the mixed liquid, so that the autotrophic denitrification and phosphorus removal agent and the microorganism containing autotrophic denitrifying bacteria are kept in suspension state in the fluidization zone (2), the denitrifying microorganism in the inoculated microorganism converts the nitrate nitrogen in the mixed liquid into nitrogen gas by using the electron donor, and the nitrogen gas is discharged to the outside of the cylinder (1) through the central pipe (9), at the same time, the biological mineralization converts the dissolved phosphate into solid iron phosphate and calcium phosphate precipitate; Fourth step, the ascending suspension of the fluidization zone is separated into sinking particulate matter and clarified liquid in the sedimentation zone (3), the clarified liquid passes through the clear water generated by the filter layer (4-2), and the clarified liquid passes through the filter layer (4-2) in the process, the filter material particle surface forms a microbial membrane, and the fine particles including free microorganisms in the clarified liquid are intercepted by the filter layer (4-2), the clear water passing through the filter layer is the treated wastewater, which is discharged to the outside of the cylinder (1) through the overflow outlet weir tank (1-10) and the outlet pipe (1-2) in turn; In the initial stage of starting the fluidized bed reactor, the opening of the valve at the inlet pipe (1-1) is gradually increased to gradually increase the inlet flow, so that the hydraulic retention time is gradually shortened to the stable operation of the fluidized bed reactor; During the stable operation of the fluidized bed reactor, if the liquid level in the central pipe (9) rises to the preset warning liquid level, The valves at the inlet pipe (1-1), the dosing pipe (1-6) and the outlet pipe (1-2) are closed, the water pump (1-8) is stopped, the backwashing inlet pipe (1-4) is opened, the backwashing discharge pipe (1-5) is opened, and the backwashing water pump is started, At the same time, the stirring shaft speed is reduced; At this time, the backwashing water flows into the water distributor (7) through the backwashing inlet pipe (1-4) from the backwashing inlet (7-1) under the action of the backwashing water pump, and then is distributed to each water distribution branch pipe (7-3) through the circular pipe (7-4), and flows out upward through each hole (7-5) of each water distribution branch pipe (7-3) to backwash the filter layer (4-2), and then flows upward and overflows through the overflow outlet weir tank (1-10) to the backwashing discharge pipe (1-5). Meanwhile, the shaft holder (6-5) of the rake mechanism (6) holds the stirring shaft (8-2), drives the rake teeth (6-1) to rotate around the axis of the stirring shaft (8-1) through the rotating beam (6-3) and the rake rod (6-2), rakes the filter material particles, discharges the bubbles accumulated between the filter material particles, and makes the filter material particles reaccumulate to re-create the gaps between the filter material particles, so as to restore the permeability of the filter layer (4-2); After the rake teeth (6-1) rotate around the axis of the stirring shaft (8-1) for 1-3 turns, the liquid level in the central pipe (9) is lowered to within 2 cm of the liquid level outside the central pipe (9), and the filtering function of the filter layer (4-2) is completely restored; Then, the backwashing water pump is stopped, the valves at the backwashing water inlet pipe (1-4) and the backwashing discharge pipe (1-5) are closed, the shaft holder (6-5) is released, the valves at the water inlet pipe (1-1), the dosing pipe (1-6) and the water outlet pipe (1-2) are opened, and the water pump (1-8) is started to continue the normal treatment of the wastewater.

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