Advanced treatment system and method for high-concentration nitrogenous organic wastewater

Abstract

The invention discloses an advanced treatment system and method for high-concentration nitrogen-containing organic wastewater, and the treatment system sequentially comprises an anaerobic tank, an anoxic tank, an aerobic tank, a secondary sedimentation tank, a sulfur autotrophic denitrification filter tank and a limestone filter tank, a water passing hole is formed in the upper part of a wall body between the anaerobic tank and the anoxic tank, a hollow aeration fiber membrane assembly is arranged in the anoxic tank, an aeration pipe is arranged at the bottom of the aerobic tank, a mixed liquid reflux pump is arranged at the bottom of the aerobic tank in a penetrating manner and is connected with the anoxic tank through a pipeline, and the aeration pipe is connected with the anoxic tank through a pipeline. A sludge reflux pump penetrates through the bottom of the secondary sedimentation tank and is connected with the anaerobic tank through a pipeline. Iron-carbon micro-electrolysis is intervened in the anaerobic reactor to achieve the purposes of improving the biodegradability of high-concentration degradation-resistant wastewater and enhancing biochemical treatment, and the nitrogen removal mode of anaerobic section MABR bubble-free aeration synchronous nitrification and denitrification is organically combined, so that the system treatment load and the activated sludge utilization rate are improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a system and method for deep treatment of high-concentration nitrogen-containing organic wastewater. Background Art

[0002] Microorganisms play a vital role in wastewater treatment. They remove organic matter from wastewater through biodegradation. However, high concentrations of chemicals in wastewater will inhibit the growth and reproduction of microorganisms. Even well-adapted microorganisms can only process relatively low concentrations of pollutants. When the content of chemicals in sewage exceeds a certain concentration, not only will the activity of microorganisms be inhibited, resulting in a decrease in the COD removal rate of wastewater, but it will even cause the sludge volume to expand, a large amount of foam to appear on the water surface, and cause the microorganisms to die one after another.

[0003] At present, for the treatment of high-nitrogen concentration wastewater, the biochemical stage usually adopts a two-stage A / O process to achieve the purpose of deep denitrification, but its aeration and sludge treatment energy consumption accounts for more than 60% of the operating energy consumption of the sewage treatment plant. The demand for organic carbon sources is high and the reactor occupies a large area. In addition, the activity of microbial growth and metabolic enzymes is low, and the pollutant removal effect is not ideal, resulting in high treatment costs. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a system and method for deep treatment of high-concentration nitrogen-containing organic wastewater to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A high-concentration nitrogen-containing organic wastewater deep treatment system, the treatment system comprises an anaerobic tank, an anoxic tank, an aerobic tank, a secondary sedimentation tank, a sulfur autotrophic denitrification filter and a limestone filter in sequence, an iron-carbon micro-electrolysis suspension ball is placed in the anaerobic tank, a water hole is arranged above the wall between the anaerobic tank and the anoxic tank, a hollow aeration fiber membrane assembly is arranged in the anoxic tank, an aeration pipe is arranged at the bottom of the aerobic tank, a mixed liquor reflux pump is arranged through the bottom of the aerobic tank and the mixed liquor reflux pump is connected to the anoxic tank through a pipeline, a sludge reflux pump is arranged through the bottom of the secondary sedimentation tank and the sludge reflux pump is connected to the anaerobic tank through a pipeline.

[0007] Preferably, a stirrer is provided in the anaerobic tank to stir the iron-carbon micro-electrolysis suspension balls, which act as conductive carriers and stimulate the secretion of extracellular polymers of microorganisms in the sludge; the iron-carbon micro-electrolysis suspension balls use biochar as an active iron carrier, with an iron-carbon mass ratio of 1:1, and are sintered at high temperature. The carrier is a spherical cavity structure with an outer diameter of 6-8 cm and an inner diameter of ≤5 cm, which has good mechanical strength and is in a flowing state in the water body. To improve the problem of easy passivation and compaction of iron-carbon fillers, a protective net is wrapped around the outside of the sphere to prevent the filler from breaking and clogging the pipeline due to fluid stirring.

[0008] Preferably, a submersible flow propeller is arranged on the wall between the anaerobic tank and the anoxic tank and in the anoxic tank.

[0009] Preferably, a plurality of microporous aeration disks are arranged above the aeration pipe.

[0010] Preferably, the fiber membrane material of the hollow aerated fiber membrane assembly is polyvinylidene fluoride (PVDF), the outer diameter of the membrane wire is 400-600 μm, the effective length is 1.5 m, and the packing density of the membrane area is 80-150 m 2 / m 3 .

[0011] Preferably, a residual sludge discharge pipe is arranged at the bottom of the secondary sedimentation tank, and a sewage lifting pump is arranged at the top of the secondary sedimentation tank, and the sewage lifting pump is connected to the bottom of the sulfur autotrophic denitrification filter tank through a pipeline.

[0012] Preferably, the sulfur autotrophic denitrification filter is provided with a gravel support layer, a composite filter material filling layer, and a water collection layer from bottom to top. The composite filter material filling layer is composed of sulfur: pyrite: siderite in a ratio of (6-9): 3: 1, and a bulk density of 1.15 t / m 3 , particle size 4-6mm, filter material filling height 2-4.5m.

[0013] Preferably, the top of the sulfur autotrophic denitrification filter is connected to the top of the limestone filter through a pipeline, and a water outlet is provided at the bottom of the limestone filter; the limestone filter is provided with a supporting layer and a filler layer from bottom to top, the supporting layer is filled with gravel with a particle size of 45-50 mm, and the filler layer is filled with granular limestone with a particle size of 20-25 mm.

[0014] Preferably, the anoxic tank and the aerobic tank are provided with variable frequency fans through pipelines, a fiber membrane air intake regulating valve is provided on the pipeline connecting the variable frequency fan and the hollow aeration fiber membrane assembly in the anoxic tank, and an aeration pipe regulating valve is provided on the pipeline connecting the variable frequency fan and the aerobic tank.

[0015] The present invention also provides a method for deep treatment of high-concentration nitrogen-containing organic wastewater, comprising the following steps:

[0016] (1) First, the sewage is flowed into the anaerobic tank, and the agitator is started to make the inside of the tank flow. Under the enhanced action of the electrolysis of the stirring iron-carbon micro-electrolysis suspended balls (11), the microorganisms efficiently degrade organic pollutants, Fe 0 It forms numerous micro primary cells with biochar in the anaerobic tank, accelerates electron transfer, reduces the redox potential of the system, and improves the conversion rate of organic matter and the biodegradability of sewage.

[0017] (2) The effluent from the anaerobic tank flows into the anoxic tank through the water hole. After 14 days of continuous biofilm acclimatization of the hollow aerated fiber membrane assembly with wastewater, a thick biofilm is formed to start the device. The aeration pressure is controlled at 0.05-0.15MP, and the DO is controlled at 0.5mg / L. Oxygen and pollutants enter the membrane from both sides of the biofilm. The aerobic layer of the biofilm undergoes nitrification reaction to oxidize and decompose organic carbon, and the anaerobic layer of the biofilm in contact with the wastewater undergoes denitrification and denitrification.

[0018] (3) The effluent from the anoxic tank is passed into the aerobic tank. The microporous aeration disk installed above the bottom aeration pipe controls the DO at 2-3 mg / L to further decompose organic matter. A mixed liquid reflux pump is installed at the bottom to pass into the anoxic tank, and the reflux ratio is set to 200-400%;

[0019] (4) The effluent from the aerobic tank enters the secondary sedimentation tank through a pipeline for mud and water separation. Part of the sludge at the bottom is passed into the anaerobic tank through a sludge return pump, and the remaining sludge is discharged through the bottom residual sludge discharge pipe. The effluent from the upper clarification area flows through the overflow port and the sewage lift pump into the sulfur autotrophic denitrification filter tank;

[0020] (5) Before starting the sulfur autotrophic denitrification filter, the biofilm was inoculated and continuously fed with wastewater for 20 days. When the biofilm was formed on the filter surface, the device was started. The effluent from the secondary sedimentation tank was fed into the packing layer of the sulfur autotrophic denitrification filter by the sewage lifting pump. The pH of the inlet water was controlled at 7-7.5. The denitrifying bacteria used S 0 and S 2- The autotrophic denitrification process removes most of the NO3 - -N is converted to N2, and the reaction produces H + The Fe in siderite 2+ Leaching, Fe 2+ As an auxiliary electron donor, it can also drive a small amount of NO3 - -N is converted into N2, and the reaction area of ​​the microorganisms on FeCO3 is expanded from the solid phase to the solid-liquid phase. At the same time, CO3 2- It can be used as a pH buffer and continuously provide inorganic carbon sources to ensure the growth and metabolism of microorganisms in the sewage treatment system. The effluent from the sulfur autotrophic denitrification filter is collected in the upper water collection layer of the reactor and discharged.

[0021] (6) The effluent from the sulfur autotrophic denitrification filter flows into the limestone filter. The water flows from top to bottom. The sulfate produced by the sulfur autotrophic denitrification process is removed by the action of the limestone particles in the filler layer. A gravel layer is laid at the bottom, and the effluent finally meets the discharge standards.

[0022] Fe in iron-carbon micro-electrolysis suspension 0 In anaerobic environments, hydrogen evolution corrosion is likely to occur. The Fe released by anode corrosion 2+ It can improve the metabolic activity of microorganisms, and the H2 released at the cathode can provide more substrates for methanogens. 0 A microscopic primary cell is formed between the iron-carbon micro-electrolysis filler and the carbon to degrade the organic matter in the wastewater. When the iron-carbon micro-electrolysis filler is mixed with the wastewater, the electron transfer can effectively stimulate the growth of microorganisms and the activity of metabolic enzymes, and further improve the biodegradation ability of microorganisms, thereby achieving the purpose of enhanced biological treatment and improving the sustainability and economy of anaerobic technology. The iron-carbon micro-electrolysis enhances the microbial treatment performance of the anaerobic tank.

[0023] The hollow aerated fiber membrane assembly belongs to the membrane aerated bioreactor (MABR). As a bubble-free aeration technology, the membrane aerated bioreactor organically combines the traditional biofilm method and the aeration membrane technology. The hollow aerated fiber membrane in the MABR pool has an excellent oxygen transmission rate. As a microbial attachment carrier, it provides bubble-free aeration for the biofilm. The submerged aeration membrane is driven by the oxygen concentration difference. Oxygen dissolves and diffuses in the membrane, gradually transitioning from the aerobic zone to the anaerobic layer, which is completely opposite to the oxygen transfer direction of the biofilm, ensuring the simultaneous nitrification and denitrification in the anoxic tank, and achieving economical and efficient denitrification. At the same time, MABR has a good removal effect on acetonitrile, formaldehyde, aminophenol and other difficult-to-degrade pollutants and volatile pollutants, and plays a significant role in the treatment of volatile organic matter and difficult-to-degrade organic wastewater. MABR has good microbial attachment and improves the efficiency of biological denitrification.

[0024] The sulfur autotrophic denitrification filter tank is provided with a gravel support layer, a composite filter material filling layer, and a water collection layer from bottom to top. The sulfur autotrophic denitrification process without the need for an external organic carbon source can alleviate this contradiction. The sulfur autotrophic denitrification has high denitrification efficiency and low energy consumption cost, and low residual sludge production. It shows good application prospects in the field of biological denitrification and is suitable for terminal deep denitrification. While ensuring the denitrification rate, it reduces the operating cost and the generation of residual sludge. The system has the characteristics of enhanced denitrification and carbon removal, strong load impact resistance, and small land occupation. The present invention is suitable for deep treatment of high-concentration organic wastewater with a low C / N ratio.

[0025] The beneficial effects of the present invention relative to the prior art are:

[0026] 1. The present invention introduces iron-carbon micro-electrolysis into the anaerobic reactor to improve the biodegradability of high-concentration refractory wastewater and strengthen the biochemical treatment, and organically combines the denitrification method of MABR bubbleless aeration and synchronous nitrification and denitrification in the anoxic section to improve the system processing load and the utilization rate of activated sludge. Compared with the traditional two-stage A / O process, this treatment system saves equipment floor space and energy consumption costs while ensuring efficient denitrification and carbon removal. Using water pumps and reflux pipes, sewage can circulate between reaction tanks to improve the sewage purification effect.

[0027] 2. The present invention uses sulfur autotrophic denitrification to perform terminal deep denitrification treatment on wastewater. No additional organic carbon source is required, and no residual organic matter will be generated to cause biological pollution of the effluent. The sulfur-iron composite filler filled in the pool promotes the formation of a multiphase denitrification reaction hot zone, accelerates the denitrification rate, and maintains the pH stability of the system. Compared with heterotrophic denitrification pools, the operating cost is saved by nearly 50%, and when the influent TN is lower than 150 mg / L, the TN removal rate is more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the high-concentration nitrogen-containing organic wastewater deep treatment system of the present invention.

[0029] The accompanying drawings are marked as follows: 1. anaerobic tank; 11. iron-carbon micro-electrolysis suspension ball; 12. agitator; 2. anoxic tank; 21. hollow aeration fiber membrane assembly; 22. submersible flow propeller; 3. aerobic tank; 31. aeration pipe; 32. microporous aeration disk; 33. mixed liquor reflux pump; 4. secondary sedimentation tank; 41. residual sludge discharge pipe; 42. sewage lifting pump; 43. sludge reflux pump; 5. sulfur autotrophic denitrification filter; 6. variable frequency fan; 7. aeration pipe air volume regulating valve; 71. fiber membrane air intake regulating valve; 8. mixed liquor reflux pump; 9. limestone filter; 91. water outlet; 10. water hole. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] A high-concentration nitrogen-containing organic wastewater deep treatment system, the treatment system comprises an anaerobic tank 1, an anoxic tank 2, an aerobic tank 3, a secondary sedimentation tank 4, a sulfur autotrophic denitrification filter 5 and a limestone filter 9 in sequence, an iron-carbon micro-electrolysis suspension ball 11 is placed in the anaerobic tank 1, a water hole 10 is arranged above the wall between the anaerobic tank 1 and the anoxic tank 2, a hollow aeration fiber membrane assembly 21 is arranged in the anoxic tank 2, an aeration pipe 3 is arranged at the bottom of the aerobic tank 3), a mixed liquor reflux pump 8 is arranged through the bottom of the aerobic tank 3 and the mixed liquor reflux pump 33 is connected to the anoxic tank 2 through a pipeline, a sludge reflux pump 43 is arranged through the bottom of the secondary sedimentation tank 4 and the sludge reflux pump 43 is connected to the anaerobic tank 1 through a pipeline.

[0032] In one embodiment, an agitator 12 is provided in the anaerobic tank 1 for stirring the iron-carbon micro-electrolysis suspension ball 11. The iron-carbon micro-electrolysis suspension ball 11 uses biochar as an active iron carrier with an iron-carbon mass ratio of 1:1. After high-temperature sintering, the carrier has a spherical cavity structure with an outer diameter of 6-8 cm and an inner diameter of ≤5 cm.

[0033] In one embodiment, a submersible flow propeller 22 is arranged on the wall between the anaerobic tank 1 and the anoxic tank 2 and in the anoxic tank 2 .

[0034] In one embodiment, a plurality of microporous aeration plates 32 are arranged above the aeration tube 31 .

[0035] In one embodiment, the fiber membrane material of the hollow aeration fiber membrane assembly 21 is polyvinylidene fluoride (PVDF), the outer diameter of the membrane wire is 400-600 μm, the effective length is 1.5 m, and the packing density of the membrane area is 80-150 m 2 / m 3 .

[0036] In one embodiment, a residual sludge discharge pipe 41 is provided at the bottom of the secondary sedimentation tank 4, and a sewage lifting pump 42 is provided at the top of the secondary sedimentation tank 4. The sewage lifting pump 42 is connected to the bottom of the sulfur autotrophic denitrification filter 5 through a pipeline.

[0037] In one embodiment, the sulfur autotrophic denitrification filter 5 is provided with a gravel support layer, a composite filter material filling layer, and a water collection layer from bottom to top. The composite filter material filling layer is composed of sulfur: pyrite: siderite in a ratio of (6-9): 3: 1, and the stacking density is 1.15 t / m 3 , particle size 4-6mm, filter material filling height 2-4.5m.

[0038] In one embodiment, the top of the sulfur autotrophic denitrification filter 5 is connected to the top of the limestone filter 9 through a pipeline, and a water outlet 91 is provided at the bottom of the limestone filter 9; the limestone filter 9 is provided with a supporting layer and a filler layer from bottom to top, the supporting layer is filled with gravel with a particle size of 45-50 mm, and the filler layer is filled with granular limestone with a particle size of 20-25 mm.

[0039] In one embodiment, the anoxic tank 2 and the aerobic tank 3 are provided with a variable frequency fan 6 through a pipeline, a fiber membrane air intake regulating valve 71 is provided on the pipeline connecting the variable frequency fan 6 and the hollow aeration fiber membrane assembly 21 in the anoxic tank 2, and an aeration pipe regulating valve 7 is provided on the pipeline connecting the variable frequency fan 6 and the aerobic tank 3.

[0040] A method for deep treatment of high-concentration nitrogen-containing organic wastewater comprises the following steps:

[0041] (1) First, the sewage is flowed into the anaerobic tank 1, and the agitator 12 is started to make the inside of the tank flow. Under the enhanced action of the electrolysis of the stirring iron-carbon micro-electrolysis suspension ball 11, the microorganisms efficiently degrade organic pollutants, Fe 0 It forms numerous micro primary cells with biochar in the anaerobic tank, accelerates electron transfer, reduces the redox potential of the system, and improves the conversion rate of organic matter and the biodegradability of sewage.

[0042] (2) The effluent from the anaerobic tank 1 flows into the anoxic tank 2 through the water hole 10. The hollow aerated fiber membrane module 21 forms a thick biofilm after 14 days of continuous biofilm acclimatization with wastewater to start the device. The aeration pressure is controlled at 0.05-0.15MP, and the DO is controlled at 0.5mg / L. Oxygen and pollutants enter the membrane from both sides of the biofilm. The aerobic layer of the biofilm undergoes nitrification reaction to oxidize and decompose organic carbon, and the anaerobic layer of the biofilm in contact with the wastewater undergoes denitrification and denitrification.

[0043] (3) The effluent from the anoxic tank 2 is passed into the aerobic tank 3. The microporous aeration disk 32 arranged above the bottom aeration pipe 31 controls the DO at 2-3 mg / L to further decompose organic matter. A mixed liquid reflux pump 8 is provided at the bottom to pass into the anoxic tank 2. The reflux ratio is set to 200-400%;

[0044] (4) The effluent from the aerobic tank 3 enters the secondary sedimentation tank 4 through a pipeline for mud and water separation. Part of the sludge at the bottom is passed into the anaerobic tank 1 through a sludge return pump 43, and the remaining sludge is discharged through the bottom remaining sludge discharge pipe 41. The effluent from the upper clarification area flows through the overflow port and the sewage lift pump 42 into the sulfur autotrophic denitrification filter 5;

[0045] (5) Before starting the sulfur autotrophic denitrification filter 5, the biofilm is inoculated and continuously fed with wastewater for 20 days. When a biofilm is formed on the filter material surface, the device is started. The effluent from the secondary sedimentation tank 4 is fed into the packing layer of the sulfur autotrophic denitrification filter 5 by the sewage lifting pump 42. The pH of the influent is controlled at 7-7.5. The denitrifying bacteria utilize S 0 and S 2- The autotrophic denitrification process removes most of the NO3 - -N is converted to N2, and the reaction produces H + The Fe in siderite 2+ Leaching, Fe 2+ As an auxiliary electron donor, it can also drive a small amount of NO3 - -N is converted into N2, and the reaction area of ​​the microorganisms on FeCO3 is expanded from the solid phase to the solid-liquid phase. At the same time, CO3 2- It can be used as a pH buffer and continuously provide an inorganic carbon source to ensure the growth and metabolism of microorganisms in the sewage treatment system. The effluent from the sulfur autotrophic denitrification filter 5 is collected in the upper water collection layer of the reactor and discharged.

[0046] (6) The effluent from the sulfur autotrophic denitrification filter 5 flows into the limestone filter 9, and the water flows from top to bottom. The sulfate produced by the sulfur autotrophic denitrification process is removed under the action of the limestone particles in the filler layer. A gravel layer is laid at the bottom, and the effluent finally meets the discharge standards.

[0047] In the embodiment, as shown in the attached Figure 1 A high-concentration nitrogen-containing organic wastewater deep treatment system is shown, which is mainly composed of an anaerobic tank 1, an anoxic tank 2, a hollow aerated fiber membrane module 21, an aerobic tank 3, a secondary sedimentation tank 4, a sulfur autotrophic denitrification filter 5 and a limestone filter 9. According to the direction of water flow, it is connected and transported by a number of inlet and outlet pipes and sewage pumps. The effluent mixed liquid of the aerobic tank 3 is transported to the anoxic tank 2 through a mixed liquid return pump 8, and the return ratio is set to 300%. The sludge of the secondary sedimentation tank 4 enters the anoxic tank 2 and the aerobic tank 3 through a sludge return pump 43, and the remaining sludge is discharged through a discharge pipe 41. The anaerobic tank 1 is equipped with a stirrer 12 to make the mixed liquid in a flowing state, and the anoxic tank 2 is equipped with a submersible flow pusher 22 for mixing, stirring and low-speed flow.

[0048] A variable frequency fan 6 is provided, which controls the air volume regulating valve 7 of the aeration pipe to pass air into the microporous aeration disk 32, controls the air volume regulating valve 71 of the aeration membrane to pass air into the hollow aeration fiber membrane module 21, and the effluent of the anoxic tank 2 flows into the aerobic tank 3 for aerobic biological treatment. The variable frequency fan 6 is connected to the aeration pipe 31 and is surrounded at the bottom of the aerobic tank 2. The microporous aeration disk 32 is evenly distributed on the aeration pipe 31 to aerate the aerobic organisms. The DO in the hollow aeration fiber membrane module is 0.5 mg / L, and the microporous aeration disk 32 controls the DO at 2-3 mg / L.

[0049] The effluent from the clarification area of ​​the secondary sedimentation tank 4 enters the sulfur autotrophic denitrification filter 5 through the sewage lifting pump 42. The filter material layer is filled with sulfur-iron composite filler, and the filter material filling height is 2m. The filler layer of the limestone filter 9 is filled with granular limestone with a particle size of 20-25mm, and the filler layer height is 1m.

[0050] Example 1

[0051] The COD of the influent of a certain landfill leachate treatment plant in the middle and late stages is 5300-5500 mg / L, TN is 1625-1700 mg / L, NH4 + -N is 1000-1230 mg / L, BOD5 / COD=0.1-0.15.

[0052] The wastewater enters the anaerobic tank 1 for biodegradation of TCOD. The anaerobic digestion bacteria fully contact and react with the iron-carbon micro-electrolysis suspension ball 11 to decompose the difficult-to-degrade organic matter in the leachate into small molecular biodegradable carbon sources. The iron cycle is used to stabilize the anaerobic digestion process. The porous ball is easy to be loaded by anaerobic bacteria. 0 The redox potential of the system is reduced, and the conversion of organic matter into methane and volatile fatty acids is significantly increased, with the methane production increased by 30%-40%. The anaerobic tank 1 is provided with a uniform speed agitator 12 to accelerate the mixing and contact of the fluid and the suspended carrier, improve the biodegradability and facilitate subsequent biological treatment. The effluent of the anaerobic tank 1 enters the anoxic tank 2, which is equipped with a hollow fiber aeration membrane assembly 21. The aeration pressure is controlled at 0.1MP, and the DO is controlled at 0.5mg / L. Oxygen permeates outward from the inner cavity of the hollow fiber aeration membrane, and NH4 + -N diffuses to the bottom of the biofilm, and nitrifying bacteria densely grow on the surface of the hollow fiber aeration membrane, maintaining a high nitrification rate. The outer layer of the biofilm has an anoxic environment suitable for the growth and proliferation of denitrifying bacteria for denitrification. At this time, simultaneous nitrification and denitrification occur on the biofilm, with a COD removal rate of 95% and a TN removal rate of 84%. The effluent from the anoxic pool 2 enters the aerobic pool 3, and the DO is controlled to 2 mg / L through the bottom aeration pipe 31 and the microporous aeration disk 32. The wastewater undergoes organic matter degradation and nitrification in the aerobic pool 3, and the remaining NH4 + -N is converted to NO3 — N, NH4 + -N removal rate reaches 89%. The effluent from aerobic pool 3 enters secondary sedimentation tank 4 through the overflow port for mud-water separation, and the concentrated sludge enters anaerobic pool 1 and aerobic pool 2 respectively through sludge return pump 43. The effluent from the upper clarifying area enters sulfur autotrophic denitrification filter 5 through sewage lifting pump 42. The autotrophic denitrifying bacteria after biofilm domestication are enriched in the packing layer and use CO3 2- As an inorganic carbon source, S 0 and S 2- As electron donor, NO3 —N is used as an electron acceptor to undergo autotrophic denitrification, converting most of the NO3 — N is reduced to N2, the hydraulic retention time is set to 8h, and the pH is controlled at 7-7.5. The effluent from the sulfur autotrophic denitrification filter 5 is collected in the water collection layer, and the COD concentration of the effluent from the biochemical system is less than 300mg / L, and NH4 + -N concentration is less than 10mg / L, effluent NO3 - The TN concentration is less than 15 mg / L, and the average TN removal rate is stable at more than 95%. The effluent from the sulfur autotrophic denitrification filter 5 flows into the limestone filter 9 for sulfate removal, and the final effluent is discharged from the outlet 91 at the bottom of the filter to meet the standards.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-concentration nitrogen-containing organic wastewater deep treatment system, characterized in that: The treatment system comprises an anaerobic tank (1), an anoxic tank (2), an aerobic tank (3), a secondary sedimentation tank (4), a sulfur autotrophic denitrification filter (5) and a limestone filter (9) in sequence. An iron-carbon micro-electrolysis suspension ball (11) is placed in the anaerobic tank (1). A water hole (10) is provided above the wall between the anaerobic tank (1) and the anoxic tank (2). A hollow aeration fiber membrane module (21) is provided in the anoxic tank (2). An aeration pipe (31) is provided at the bottom of the aerobic tank (3). A mixed liquor return pump (8) is provided through the bottom of the aerobic tank (3) and the mixed liquor return pump (33) is connected to the anoxic tank (2) through a pipeline. A sludge return pump (43) is provided through the bottom of the secondary sedimentation tank (4) and the sludge return pump (43) is connected to the anaerobic tank (1) through a pipeline.

2. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: A stirrer (12) is arranged in the anaerobic tank (1) for stirring the iron-carbon micro-electrolysis suspension ball (11). The iron-carbon micro-electrolysis suspension ball (11) uses biochar as an active iron carrier with an iron-carbon mass ratio of 1:

1. After high-temperature sintering, the carrier has a spherical cavity structure with an outer diameter of 6-8 cm and an inner diameter of ≤5 cm.

3. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: A submersible flow propeller (22) is arranged on the wall between the anaerobic tank (1) and the anoxic tank (2) and in the anoxic tank (2).

4. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: A plurality of microporous aeration plates (32) are arranged above the aeration pipe (31).

5. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: The fiber membrane in the hollow aeration fiber membrane assembly (21) is made of polyvinylidene fluoride (PVDF), the outer diameter of the membrane wire is 400-600 μm, the effective length is 1.5 m, and the packing density of the membrane area is 80-150 m 2 / m 3 .

6. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: A residual sludge discharge pipe (41) is arranged at the bottom of the secondary sedimentation tank (4), and a sewage lifting pump (42) is arranged at the top of the secondary sedimentation tank (4). The sewage lifting pump (42) is connected to the bottom of the sulfur autotrophic denitrification filter (5) through a pipeline.

7. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 6, characterized in that: The sulfur autotrophic denitrification filter (5) is provided with a gravel support layer, a composite filter material filling layer, and a water collection layer from bottom to top. The composite filter material filling layer is composed of sulfur: pyrite: siderite in a ratio of (6-9): 3: 1, and a bulk density of 1.15 t / m 3 , particle size 4-6mm, filter material filling height 2-4.5m.

8. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: The top of the sulfur autotrophic denitrification filter (5) is connected to the top of the limestone filter (9) through a pipeline, and the bottom of the limestone filter (9) is provided with a water outlet (91); the limestone filter (9) is provided with a supporting layer and a filler layer from bottom to top, the supporting layer is filled with gravel with a particle size of 45-50 mm, and the filler layer is filled with granular limestone with a particle size of 20-25 mm.

9. A high-concentration nitrogen-containing organic wastewater deep treatment system according to claim 1, characterized in that: The anoxic pool (2) and the aerobic pool (3) are provided with a variable frequency fan (6) through a pipeline, a fiber membrane air intake regulating valve (71) is provided on the pipeline connecting the variable frequency fan (6) and the hollow aeration fiber membrane assembly (21) in the anoxic pool (2), and an aeration pipe regulating valve (7) is provided on the pipeline connecting the variable frequency fan (6) and the aerobic pool (3).

10. A method for deep treatment of high-concentration nitrogen-containing organic wastewater according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) First, the sewage is flowed into the anaerobic tank (1), and the agitator (12) is started to make the inside of the tank flow. Under the enhanced action of the electrolysis of the stirring iron-carbon micro-electrolysis suspension ball (11), the microorganisms efficiently degrade organic pollutants, Fe 0 It forms numerous micro primary cells with biochar in the anaerobic tank, accelerates electron transfer, reduces the redox potential of the system, and improves the conversion rate of organic matter and the biodegradability of sewage; (2) The effluent from the anaerobic tank (1) flows into the anoxic tank (2) through the water hole (10), and the hollow aerated fiber membrane assembly (21) forms a thick biofilm after 14 days of continuous biofilm acclimatization by wastewater to start the device, and the aeration pressure is controlled to be 0.05-0.15MP, and the DO is controlled to be 0.5mg / L. Oxygen and pollutants enter the membrane from both sides of the biofilm, and the aerobic layer of the biofilm undergoes nitrification reaction to oxidize and decompose organic carbon, and the anaerobic layer of the biofilm in contact with the wastewater undergoes denitrification and denitrification; (3) The effluent from the anoxic tank (2) is introduced into the aerobic tank (3). The microporous aeration disk (32) arranged above the bottom aeration pipe (31) controls the DO at 2-3 mg / L to further decompose organic matter. A mixed liquid reflux pump (8) is provided at the bottom to pass into the anoxic tank (2). The reflux ratio is set at 200-400%. (4) The effluent from the aerobic tank (3) enters the secondary sedimentation tank (4) through a pipeline for mud and water separation. Part of the sludge at the bottom is passed into the anaerobic tank (1) through a sludge return pump (43), and the remaining sludge is discharged through a bottom remaining sludge discharge pipe (41). The effluent from the upper clarification area flows through an overflow port and a sewage lifting pump (42) into a sulfur autotrophic denitrification filter (5); (5) Before starting the sulfur autotrophic denitrification filter (5), the biofilm is inoculated and continuously fed with wastewater for 20 days. When a biofilm is formed on the filter material surface, the device is started. The effluent from the secondary sedimentation tank (4) is fed into the packing layer of the sulfur autotrophic denitrification filter (5) by the sewage lifting pump (42). The pH of the influent is controlled at 7-7.

5. The denitrifying bacteria utilize S 0 and S 2- The autotrophic denitrification process removes most of the NO3 - -N is converted to N2, and the reaction produces H + The Fe in siderite 2+ Leaching, Fe 2+ As an auxiliary electron donor, it can also drive a small amount of NO3 - -N is converted into N2, and the reaction area of ​​the microorganisms on FeCO3 is expanded from the solid phase to the solid-liquid phase. At the same time, CO3 2- It can be used as a pH buffer and continuously provide an inorganic carbon source to ensure the growth and metabolism of microorganisms in the sewage treatment system. The effluent from the sulfur autotrophic denitrification filter (5) is collected in the upper water collection layer of the reactor and discharged. (6) The effluent from the sulfur autotrophic denitrification filter (5) flows into the limestone filter (9) with the water flowing from top to bottom. The sulfate produced by the sulfur autotrophic denitrification process is removed by the action of the limestone particles in the filler layer. A gravel layer is laid at the bottom, and the effluent finally meets the discharge standards.

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