Segmented influent multi-point reflux enhanced autotrophic nitrogen removal system for municipal wastewater and method thereof

Abstract

The present application provides a kind of segmented water inlet multi-point reflux enhanced municipal wastewater autotrophic denitrification system and method thereof, the system includes biochemical pool, sedimentation tank, water inlet pipe or water inlet corridor, connecting pipe, water outlet pipe, nitration liquid reflux pipe, sludge reflux pipe, supernatant reflux pipe and sludge discharge pipe.The system combines multiple microbial aggregation forms such as pure biofilm, biofilm and flocculent sludge coexistence, pure flocculent sludge, etc.in biochemical pool, plays their respective advantages, and regulates the distribution of organic matter, ammonia nitrogen and nitrate nitrogen in each section through segmented water inlet and multi-point reflux mode, to enhance the operation effect of system through anaerobic ammonium oxidation autotrophic denitrification.The present application has strong implementability, is convenient for traditional process modification, easy to operate, stable and other characteristics, and is helpful for the popularization and application of municipal wastewater autotrophic denitrification technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of sewage treatment, and relates to a sewage treatment system and a method thereof, in particular to a segmented water-inlet multi-point reflux reinforced municipal sewage autotrophic denitrification system and a method thereof. BACKGROUND

[0002] At present, biological method is generally used as secondary treatment in municipal sewage treatment plants, and the removal of nitrogen in sewage is mainly realized through the traditional process of nitrification / denitrification. Although the nitrification / denitrification sewage treatment process can convert the nitrate nitrogen produced in the aerobic section into nitrogen gas by using the carbon source in the sewage, but due to the insufficient carbon source of municipal sewage itself, additional carbon source is still needed to realize the total nitrogen of the effluent to meet the standard, which undoubtedly increases the operation cost of the sewage treatment plant. In addition, a large amount of oxygen is needed for the traditional nitrification reaction to convert ammonia nitrogen into nitrate nitrogen, resulting in a large amount of energy consumption of the aeration system. How to optimize and transform the municipal sewage treatment process, realize energy saving and consumption reduction, and improve the quality and efficiency, is an important exploration direction for the development of the industry.

[0003] As a new type of sewage treatment technology, anaerobic ammonia oxidation can realize autotrophic denitrification, and anaerobic ammonia oxidation bacteria directly convert ammonia nitrogen and nitrite into nitrogen gas. Compared with the traditional nitrification / denitrification sewage treatment process, this technology basically does not need carbon source, and its application in the sewage treatment process can effectively reduce the demand for carbon source and save the consumption of oxygen. At present, short-cut denitrification coupled with anaerobic ammonia oxidation and short-cut nitrification coupled with anaerobic ammonia oxidation are the main research and application directions of anaerobic ammonia oxidation technology. How to combine these two technical directions with the existing sewage treatment process and improve the proportion of autotrophic denitrification of sewage is the main problem.

[0004] Therefore, it is an urgent problem to design and develop a new type of anaerobic ammonia oxidation autotrophic denitrification system and method which is easy to transform the traditional process, convenient to operate and stable in effect. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide a segmented water-inlet multi-point reflux reinforced municipal sewage autotrophic denitrification system, which can be in-situ transformed on the basis of the existing sewage treatment structure, is easy to implement, convenient to operate, stable in effect, and can promote the low-carbon and efficient treatment of municipal sewage.

[0006] Another purpose of the present application is to provide a method for segmented water-inlet multi-point reflux reinforced municipal sewage autotrophic denitrification.

[0007] In order to achieve the above purpose, the present application provides a system for segmented water-inlet multi-point reflux reinforced municipal sewage autotrophic denitrification, which comprises a biochemical tank, a sedimentation tank, a water inlet pipe or a water inlet corridor, a connecting pipe, a water outlet pipe, a nitrification liquid reflux pipe, a sludge reflux pipe, a supernatant liquid reflux pipe and a sludge discharge pipe.

[0008] wherein the biochemical tank is sequentially provided with a first anoxic zone, a second anoxic zone, a first aerobic zone, and a second aerobic zone;

[0009] The water inlet pipe comprises a water inlet main pipe and a first water inlet pipe and a second water inlet pipe connected at the end of the water inlet main pipe;

[0010] The water inlet corridor comprises a water inlet main corridor and a first water inlet corridor and a second water inlet corridor connected at the end of the water inlet main corridor;

[0011] The first water inlet pipe or the first water inlet corridor is connected to the first anoxic zone, and the second water inlet pipe or the second water inlet corridor is connected to the second anoxic zone;

[0012] The connecting pipe is connected to the second aerobic zone and the sedimentation tank;

[0013] The water outlet pipe is connected to the sedimentation tank;

[0014] The nitration liquid reflux pipe is connected to the second aerobic zone and the second anoxic zone;

[0015] The sludge reflux pipe is connected to the bottom of the sedimentation tank and the second anoxic zone;

[0016] The supernatant liquid reflux pipe is connected to the upper part of the sedimentation tank and the first anoxic zone;

[0017] The first anoxic zone is provided with fixed fillers;

[0018] The first aerobic zone is provided with fixed fillers.

[0019] Preferably, the fixed fillers provided in the first anoxic zone have a filling ratio of 30-50 v / v%, and the fixed fillers provided in the first aerobic zone have a filling ratio of 30-50 v / v%.

[0020] The fillers provide a living environment for the attached microorganisms and promote the formation of biofilms.

[0021] Preferably, the fixed fillers are polyurethane sponge fillers or high-density polyethylene porous plastic fillers.

[0022] Alternatively, the fixed fillers are a mixture of polyurethane sponge fillers and high-density polyethylene porous plastic fillers; wherein the quantity ratio of polyurethane sponge fillers to high-density polyethylene porous plastic fillers is 1:1.

[0023] Preferably, the bottom of the first anoxic zone is provided with one or more submersible mixers, and the bottom of the second anoxic zone is provided with one or more submersible mixers.

[0024] The submersible mixers in the two zones realize the mixing and disturbance of the water inlet and the reflux, and promote the contact and transmission of substances and microorganisms.

[0025] Preferably, one or more aeration discs are arranged at the bottom of the first aerobic zone and one or more aeration discs are arranged at the bottom of the second aerobic zone.

[0026] The aeration discs disperse compressed air in water, improving the oxygen transfer efficiency.

[0027] The application also provides a segmented water feeding and multi-point reflux enhanced municipal wastewater autotrophic denitrification method, comprising the following steps:

[0028] 1) Municipal wastewater with a flow rate of 1Q is divided into two streams and fed into the biochemical tank of the segmented water feeding and multi-point reflux enhanced municipal wastewater autotrophic denitrification system; wherein the wastewater amount entering the first anoxic zone is controlled at 0.2Q-0.5Q, the remaining wastewater enters the second anoxic zone, the supernatant reflux amount is controlled at 0.2Q-1Q, the sludge reflux amount is controlled at 1Q-1.5Q, and the nitrification liquid reflux amount is controlled at 0.5Q-1Q.

[0029] 2) The hydraulic retention time of the first anoxic zone is 1-2h, the hydraulic retention time of the second anoxic zone is 2-4h, the hydraulic retention time of the first aerobic zone is 5-10h, and the hydraulic retention time of the second aerobic zone is 2-4h.

[0030] 3) Part of the effluent of the second aerobic zone is refluxed to the second anoxic zone as nitrification liquid, and the nitrification liquid reflux amount is 0.5Q-1Q, and the remaining effluent enters the sedimentation tank.

[0031] 4) The supernatant part of the sedimentation tank is refluxed to the first anoxic zone, and the reflux amount is 0.2Q-1Q; the sludge precipitated is refluxed to the second anoxic zone, and the reflux amount is 1Q-1.5Q; and the remaining water is discharged.

[0032] Preferably, the floc sludge concentration from the second anoxic zone to the second aerobic zone is 3000-6000mg / L.

[0033] Preferably, the dissolved oxygen concentration in the first aerobic zone is 1.0-2.5mg / L.

[0034] Preferably, the dissolved oxygen concentration in the second aerobic zone is 3-5mg / L.

[0035] The first anoxic zone of the biochemical tank provided by the application is a pure biofilm reaction zone, part of the wastewater and the supernatant of the sedimentation tank are refluxed into the reaction zone, anaerobic ammonia oxidation bacteria are enriched in the biofilm, and compared with the symbiotic system of sludge and biofilm, the pure biofilm can avoid competition for substrates between the floc sludge and the biofilm, providing better reaction conditions for short-cut denitrification coupled with anaerobic ammonia oxidation; organic matter, ammonia nitrogen, and nitrate nitrogen in water are simultaneously removed through denitrification, short-cut denitrification coupled with anaerobic ammonia oxidation, etc.

[0036] The second anoxic zone of the biochemical pool is an activated sludge zone, part of sewage, return sludge and nitrification liquid return into the reaction zone, and microorganisms in the floc sludge convert nitrate nitrogen in the return liquid into nitrogen gas by taking organic matter in the sewage as a carbon source.

[0037] The first aerobic zone of the biochemical pool is a mixed zone of biofilm and floc sludge, and the nitrification reaction, short-cut nitrification and anaerobic ammonia oxidation are simultaneously carried out in the reaction zone. After the treatment of the sewage by the front-end anoxic zone, the remaining ammonia nitrogen and organic matter are further treated in the first aerobic zone. The ammonia nitrogen in the sewage is converted into nitrate nitrogen by the nitrification reaction, and is converted into nitrogen gas by the short-cut nitrification and anaerobic ammonia oxidation reaction.

[0038] The second aerobic zone of the biochemical pool is a floc sludge zone, which is responsible for converting all the remaining ammonia nitrogen in the water into nitrate nitrogen to ensure that the ammonia nitrogen in the effluent meets the standard, and the nitrification liquid is returned to the front-end second anoxic zone from the reaction zone.

[0039] The sludge-water mixture of the biochemical pool enters the sedimentation tank and is subjected to sludge-water separation in the sedimentation tank. The sludge precipitated at the bottom is partially returned to the second anoxic zone of the biochemical pool, and part of the sludge is discharged from the system in the form of residual sludge. Part of the supernatant at the upper part of the sedimentation tank is returned to the first anoxic zone of the biochemical pool, and the remaining part of the supernatant is discharged from the system as effluent. Part of the supernatant is returned to the first anoxic zone of the biochemical pool to ensure that the biofilm form is maintained in the region without forming floc sludge.

[0040] The present application has the following beneficial effects:

[0041] The present application provides a segmented water-inlet multi-point return enhanced municipal sewage autotrophic denitrification system and autotrophic denitrification method. The system combines pure biofilm, mud film symbiosis and pure floc sludge three microbial aggregation forms, can fully exert the advantages of each form of sludge, creates favorable conditions for system autotrophic denitrification, significantly reduces the demand for external carbon source, and reduces aeration energy consumption. The system can be in-situ modified on the basis of existing sewage treatment structures, is easy to implement, is convenient to operate, has stable effect, and can promote low-carbon and efficient treatment of municipal sewage. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The figure is a schematic diagram of a preferred embodiment of the segmented water-inlet multi-point return enhanced municipal sewage autotrophic denitrification system provided by the present application.

[0043] Figure 2 The figure is a schematic diagram of another preferred embodiment of the segmented water-inlet multi-point return enhanced municipal sewage autotrophic denitrification system provided by the present application.

[0044] REFERENCE NUMERALS

[0045] 1: biochemical tank; 11: first anoxic zone; 12: second anoxic zone; 13: first aerobic zone; 14: second aerobic zone; 2: sedimentation tank; 31: water inlet pipe; 31': water inlet corridor; 311: water inlet main pipe; 311': water inlet main corridor; 312: first water inlet pipe; 312': first water inlet corridor; 313: second water inlet pipe; 313': second water inlet corridor; 32: connecting pipe; 33: water outlet pipe; 34: nitrification liquid reflux pipe; 35: sludge reflux pipe; 36: supernatant reflux pipe; 37: sludge discharge pipe; 4: filler; 5: submersible agitator; 6: aeration disc. DETAILED DESCRIPTION

[0046] The following description and drawings sufficiently illustrate specific embodiments of the present application to enable those skilled in the art to practice the same. The examples represent only a small subset of the possible variations. Individual components and functions are optional unless explicitly required, and the order of operations can be varied. Portions and features of some embodiments can be included or substituted in other embodiments.

[0047] As Figure 1 shown is a preferred embodiment of the segmented water inlet multi-point reflux enhanced municipal sewage autotrophic nitrogen removal system provided by the present application. From Figure 1 it can be seen that it comprises: a biochemical tank 1, a sedimentation tank 2, a water inlet pipe 31, a connecting pipe 32, a water outlet pipe 33, a nitrification liquid reflux pipe 34, a sludge reflux pipe 35, a supernatant reflux pipe 36, and a sludge discharge pipe 37;

[0048] wherein the biochemical tank 1 is sequentially provided with a first anoxic zone 11, a second anoxic zone 12, a first aerobic zone 13, and a second aerobic zone 14;

[0049] The water inlet pipe 31 comprises a water inlet main pipe 311 and a first water inlet pipe 312 and a second water inlet pipe 313 connected at the end of the water inlet main pipe 311, the first water inlet pipe 312 is connected to the first anoxic zone 11, and the second water inlet pipe 313 is connected to the second anoxic zone 12;

[0050] The connecting pipe 32 connects the second aerobic zone 14 and the sedimentation tank 2;

[0051] The water outlet pipe 33 connects the sedimentation tank 2;

[0052] The nitrification liquid reflux pipe 34 connects the second aerobic zone 14 and the second anoxic zone 12;

[0053] The sludge reflux pipe 35 connects the bottom of the sedimentation tank 2 and the second anoxic zone 12;

[0054] The supernatant reflux pipe 36 connects the upper part of the sedimentation tank 2 and the first anoxic zone 11;

[0055] The first anoxic zone 11 is provided with fixed fillers 4, and the filling ratio is 30-50% by volume

[0056] The first aerobic zone 13 is provided with fixed fillers 4, and the filling ratio is 30-50% by volume.

[0057] The fixed fillers are fillers fixed in the space of the first anoxic zone or the first aerobic zone by wires, nets, etc. so as not to flow with the sewage.

[0058] The fixed fillers are polyurethane sponge fillers and high-density polyethylene porous plastic fillers, and the number ratio of the two is 1:1.

[0059] The polyurethane sponge filler is a filler made of polyurethane sponge, and the high-density polyethylene porous plastic filler is a porous plastic filler made of high-density polyethylene material. Both of them are commercial products.

[0060] Due to the different scales of sewage treatment plants, when the scale of the sewage treatment plant is large, the inflow of the inflow pipe is relatively small compared with the biochemical tank, so an inflow corridor is built to increase the inflow, as shown in Figure 2 , wherein the inflow pipe 31 is replaced by the inflow corridor 31', the corresponding inflow main pipe 311 is replaced by the inflow main corridor 311', the first inflow pipe 312 is replaced by the first inflow corridor 312', and the second inflow pipe 313 is replaced by the second inflow corridor 313'.

[0061] The above system is used for the method for strengthening municipal sewage autotrophic denitrification by segmented inflow and multi-point reflux, as shown in Figure 1 , the method includes the following processes, wherein the arrows represent the water flow direction in the pipeline:

[0062] The hydraulic retention time of the biochemical tank is controlled at 10-20h, wherein the hydraulic retention time of the first anoxic zone is controlled at 1-2h, the second hydraulic retention time is 2-4h, the hydraulic retention time of the first aerobic zone is 5-10h, and the hydraulic retention time of the second aerobic zone is 2-4h; the municipal sewage with a flow rate of 1Q is divided into two streams and enters the biochemical tank, wherein the sewage amount entering the first anoxic zone is controlled at 0.2Q-0.5Q, the remaining sewage enters the second anoxic zone, the supernatant return flow is controlled at 0.2Q-1Q, the sludge return flow is controlled at 1Q-1.5Q, and the nitrification liquid return flow is controlled at 0.5Q-1Q; the flocculent sludge concentration from the second anoxic zone to the second aerobic zone is controlled at 3000-6000mg / L; the dissolved oxygen concentration of the first aerobic zone is controlled at 1.0-2.5mg / L to provide suitable dissolved oxygen conditions for short-cut nitrification and anammox; the dissolved oxygen concentration of the second aerobic zone is controlled at more than 3mg / L to ensure the nitrification rate and convert all ammonia nitrogen in the water into nitrate nitrogen; the fillers in the first anoxic zone and the first aerobic zone are fixed fillers, and the filler type is polyurethane sponge filler and / or high-density polyethylene porous filler, and the filling ratio is 30-50%.

[0063] The fixed fillers are more likely to be attached by microorganisms, and the biofilm is not likely to fall off in large quantities due to filler collision, and the fillers are not likely to be accumulated in a certain direction in the biochemical tank to increase the back blowing cost.

[0064] The reaction principle of the above-mentioned segmented water-inlet multi-point return enhanced autotrophic denitrification method for municipal sewage lies in that:

[0065] The municipal sewage is divided into two streams and enters the biochemical tank, the first stream of sewage enters the first anoxic zone, is mixed with the supernatant return flow, and is synchronously removed from organic matter, ammonia nitrogen, and nitrate nitrogen in the sewage by the action of the biofilm microorganism through the denitrification, short-cut denitrification and anammox reaction. The first anoxic zone is a pure biofilm reaction zone, and the anammox bacteria are enriched in the biofilm. Compared with the sludge-biofilm symbiotic system, the pure biofilm can avoid the competition between the flocculent sludge and the biofilm for the substrate, and provide better reaction conditions for the short-cut denitrification and anammox. The other stream of sewage enters the second anoxic zone, is mixed with the sludge return flow and the nitrification liquid return flow, and the flocculent sludge synchronously removes the organic matter and nitrate nitrogen in the sewage, and simultaneously realizes the complete removal of the nitrate nitrogen in the return flow liquid by using the large specific surface area of the flocculent sludge.

[0066] After treatment in the anoxic zones (first and second anoxic zones) of the biological treatment tank, the remaining ammonia nitrogen and some unremoved organic matter flow into the first aerobic zone, where biofilm and flocculent sludge coexist. Nitrification and short-cut nitrification coupled with anaerobic ammonium oxidation occur simultaneously in this zone. Organic matter in the wastewater is further removed by aerobic microorganisms. Some ammonia nitrogen is converted to nitrate nitrogen through nitrification, and some is converted to nitrogen gas through short-cut nitrification coupled with anaerobic ammonium oxidation. After these anoxic and aerobic treatments, some ammonia nitrogen may remain in the water. To ensure that the effluent ammonia nitrogen meets standards, the second aerobic zone of the biological treatment tank is a flocculent sludge zone, responsible for converting all remaining ammonia nitrogen into nitrate nitrogen. Simultaneously, the nitrified liquid is returned from this zone to the upstream second anoxic zone to improve the system's total nitrogen removal rate.

[0067] The mud-water mixture from the biological treatment tank enters the sedimentation tank, where mud and water are separated. Part of the sludge settled at the bottom is returned to the second anoxic zone of the biological treatment tank, and part is discharged from the system as excess sludge. Part of the supernatant at the top of the sedimentation tank is returned to the first anoxic zone of the biological treatment tank, and the remaining supernatant flows out of the system as effluent.

[0068] Example 1

[0069] The main water quality indicators of the effluent from the fine screen of a wastewater treatment plant are as follows: NH3-N 22.6~48.5mg / L; TN 30.5~68.7mg / L; BOD 105.0~137mg / L; COD 155.0~431.0mg / L; TP 3.05~6.88mg / L. The treatment method adopted is... Figure 1 The segmented influent multi-point recirculation enhanced municipal wastewater autotrophic denitrification system shown is used for autotrophic denitrification.

[0070] The hydraulic retention time of the biochemical tank is controlled at 15h under the condition that the water temperature is 20-25°C, wherein the hydraulic retention time of the first anoxic zone is controlled at 2h, the hydraulic retention time of the second anoxic zone is controlled at 4h, the hydraulic retention time of the first aerobic zone is controlled at 7h, and the hydraulic retention time of the second aerobic zone is controlled at 2h; the municipal sewage with a flow rate of 14.6L / h is divided into two streams and enters the biochemical tank, wherein the sewage entering the first anoxic zone is 4.4L / h, the remaining sewage enters the second anoxic zone, the backflow rate of the supernatant is controlled at 14.6L / h, the backflow rate of the sludge is controlled at 14.6L / h, and the backflow rate of the nitrated liquid is controlled at 7.3L / h; the flocculent sludge concentration from the second anoxic zone to the second aerobic zone is controlled at 4000-5000mg / L; the dissolved oxygen concentration of the first aerobic zone is controlled at 1.5-2.0mg / L; the dissolved oxygen concentration of the second aerobic zone is controlled at more than 3mg / L to ensure the nitrating rate and convert all the ammonia nitrogen in the water into nitrate nitrogen; the fillers in the first anoxic zone and the first aerobic zone are fixed fillers, the filler type is fixed filler, the filler type is polyurethane sponge filler and high-density polyethylene porous filler (quantity ratio 1:1), and the filling ratio is 50%. Under the above control conditions, the system is operated, and under the condition that no external carbon source is added, the effluent water quality of the system is as follows: COD: 15-30mg / L, NH4-N<1mg / L, TN<10mg / L, and TP<0.5mg / L.

[0071] Example 2

[0072] The water quality of the fine grid effluent of a certain sewage treatment plant is as follows: NH3-N 22.6-48.5mg / L; TN 30.5-68.7mg / L; BOD 105.0-137mg / L; COD 155.0-431.0mg / L; TP 3.05-6.88mg / L, and the segmented water-inlet multi-point backflow enhanced municipal sewage autotrophic denitrification system shown in the figure is used for autotrophic denitrification. Figure 1

[0073] ​The hydraulic retention time of the biochemical tank is controlled at 15h under the condition that the water temperature is 20-25°C, wherein the hydraulic retention time of the first anoxic zone is controlled at 2h, the hydraulic retention time of the second anoxic zone is controlled at 4h, the hydraulic retention time of the first aerobic zone is controlled at 7h, and the hydraulic retention time of the second aerobic zone is controlled at 2h; the municipal sewage with a flow rate of 14.6L / h is divided into two streams and enters the biochemical tank, wherein the sewage entering the first anoxic zone is 4.4L / h, the remaining sewage enters the second anoxic zone, the backflow rate of the supernatant is controlled at 14.6L / h, the backflow rate of the sludge is controlled at 14.6L / h, and the backflow rate of the nitrated liquid is controlled at 7.3L / h; the flocculent sludge concentration from the second anoxic zone to the second aerobic zone is controlled at 4000-5000mg / L; the dissolved oxygen concentration of the first aerobic zone is controlled at more than 4mg / L; the dissolved oxygen concentration of the second aerobic zone is controlled at more than 3mg / L, so as to ensure the nitrating rate and convert all the ammonia nitrogen in the water into nitrate nitrogen; the fillers in the first anoxic zone and the first aerobic zone are fixed fillers, the filler type is high-density polyethylene porous filler, and the filling ratio is 50%. Under the above control conditions, the system is operated, and under the condition that no external carbon source is added, the water quality of the system is as follows: COD: 15-30mg / L, NH4-N<1mg / L, TN<15mg / L, and TP<0.5mg / L.

[0074] Example 3

[0075] The water quality of the fine grid effluent of a certain sewage treatment plant is as follows: NH3-N 22.6-48.5mg / L; TN 30.5-68.7mg / L; BOD 105.0-137mg / L; COD 155.0-431.0mg / L; TP 3.05-6.88mg / L, and the segmented water-inlet multi-point backflow enhanced municipal sewage autotrophic denitrification system shown in the figure is used for autotrophic denitrification. Figure 1

[0076] ​The hydraulic retention time of the biochemical tank is controlled at 15h under the condition that the water temperature is 20-25℃, wherein the hydraulic retention time of the first anoxic zone is controlled at 2h, the hydraulic retention time of the second anoxic zone is controlled at 4h, the hydraulic retention time of the first aerobic zone is controlled at 7h, and the hydraulic retention time of the second aerobic zone is controlled at 2h; the municipal sewage with a flow rate of 14.6L / h is divided into two streams and enters the biochemical tank, wherein the sewage amount entering the first anoxic zone is 4.4L / h, the remaining sewage enters the second anoxic zone, the supernatant return flow is controlled at 14.6L / h, the sludge return flow is controlled at 14.6L / h, and the nitrification liquid return flow is controlled at 7.3L / h; the flocculent sludge concentration from the second anoxic zone to the second aerobic zone is controlled at 4000-5000mg / L; the dissolved oxygen concentration of the first aerobic zone is controlled at 1.5-2.0mg / L; the dissolved oxygen concentration of the second aerobic zone is controlled at 1-2mg / L; the fillers in the first anoxic zone and the first aerobic zone are fixed fillers, the filler type is polyurethane sponge filler, and the filling ratio is 30%. Under the system operation under the above control conditions, without adding external carbon source, the effluent water quality of the system is as follows: COD: 15-30mg / L, NH4-N<2mg / L, TN<15mg / L, and TP<0.8mg / L.

[0077] As can be seen from the above examples, the segmented water feeding multi-point return enhanced municipal sewage autotrophic denitrification system and method provided by the present application combines pure biofilm, mud film symbiosis and pure flocculent sludge three microbial aggregation forms, can fully exert the advantages of each form of sludge, and creates favorable conditions for autotrophic denitrification of the system.

[0078] Since the economic cost, human cost and time cost involved in building a new construction treatment area for process improvement of a traditional sewage treatment plant are very high, and the transformation based on the traditional process structure not only saves investment, but also shortens the construction period and reduces the influence on the normal operation of the sewage treatment plant. The present application can realize the operation of the new system based on the existing sewage treatment construction area of the sewage treatment plant through region selection, pipeline adjustment and filler setting, and the effect is stable, which can promote the low-carbon and efficient treatment of municipal sewage. At the same time, the municipal sewage treatment plant generally uses nitrification / denitrification process to remove ammonia nitrogen in water, and the aeration energy consumption is high during operation, and carbon source needs to be added to ensure the denitrification effect of the system. The system of the present application can significantly reduce the input of additional carbon source, and can realize the denitrification effect of the system by combining limited aeration with anaerobic reaction, thereby reducing the energy consumption and operation cost of municipal sewage treatment.

[0079] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A segmented influent multi-point reflux enhanced municipal wastewater autotrophic denitrification system, characterized in that, The system comprises a biochemical tank, a sedimentation tank, an inlet pipe or an inlet corridor, a connecting pipe, an outlet pipe, a nitrification liquid return pipe, a sludge return pipe, a supernatant return pipe and a sludge discharge pipe. The biochemical tank comprises a first anoxic zone, a second anoxic zone, a first aerobic zone and a second aerobic zone in sequence. When the inlet pipe is used, the inlet pipe comprises an inlet main pipe and a first inlet pipe and a second inlet pipe connected to the end of the inlet main pipe. When the inlet corridor is used, the inlet corridor comprises an inlet main corridor and a first inlet corridor and a second inlet corridor connected to the end of the inlet main corridor. The first inlet pipe or the first inlet corridor is connected to the first anoxic zone, and the second inlet pipe or the second inlet corridor is connected to the second anoxic zone. The connecting pipe is connected to the second aerobic zone and the sedimentation tank. The outlet pipe is connected to the sedimentation tank. The nitrification liquid return pipe is connected to the second aerobic zone and the second anoxic zone. The sludge return pipe is connected to the bottom of the sedimentation tank and the second anoxic zone. The supernatant return pipe is connected to the upper part of the sedimentation tank and the first anoxic zone. The first anoxic zone is provided with fixed fillers. The first aerobic zone is provided with fixed fillers. The first anoxic zone is provided with one or more submersible mixers at the bottom, and the second anoxic zone is provided with one or more submersible mixers at the bottom. The first aerobic zone is provided with one or more aeration discs at the bottom, and the second aerobic zone is provided with one or more aeration discs at the bottom.

2. The step feed multiple influent return enhanced municipal wastewater autotrophic denitrification system according to claim 1, characterized in that, The filling ratio of the fixed fillers provided in the first anoxic zone is 30-50v / v%, and the filling ratio of the fixed fillers provided in the first aerobic zone is 30-50v / v%.

3. The step feed multiple influent return enhanced municipal wastewater autotrophic denitrification system according to claim 1, characterized in that, The fixed fillers are polyurethane sponge fillers or high-density polyethylene porous plastic fillers.

4. The segmented feed-forward multi-point return enhanced municipal wastewater autotrophic denitrification system of claim 1, wherein, The fixed fillers are a mixture of polyurethane sponge fillers and high-density polyethylene porous plastic fillers, and the ratio of the polyurethane sponge fillers to the high-density polyethylene porous plastic fillers is 1:

1.

5. A method for enhanced autotrophic nitrogen removal from municipal wastewater by step feed multi-point reflux, characterized in that, The method comprises the following steps: 1) The total flow rate of municipal sewage entering the system is defined as Q, and the municipal sewage is divided into two streams and sent into the biochemical tank of the segmented inlet multi-point return enhanced municipal sewage autotrophic denitrification system according to any one of claims 1 to 4; wherein the first stream of sewage is sent into the first anoxic zone, and the flow rate of the first stream of sewage is 0.2Q-0.5Q; the second stream of sewage is sent into the second anoxic zone, and the flow rate of the second stream of sewage is 0.5Q-0.8Q; 2) The hydraulic retention time of the first anoxic zone is 1-2h, the hydraulic retention time of the second anoxic zone is 2-4h, the hydraulic retention time of the first aerobic zone is 5-10h, and the hydraulic retention time of the second aerobic zone is 2-4h; 3) A part of the effluent of the second aerobic zone is returned to the second anoxic zone as nitrification liquid, and the return flow rate of the nitrification liquid is 0.5Q-1Q, and the remaining effluent enters the sedimentation tank; 4) The return flow rate of the supernatant of the sedimentation tank is 0.2Q-1Q, and the return liquid returns to the first anoxic zone; the sludge at the bottom of the sedimentation tank returns to the second anoxic zone, and the return flow rate is 1Q ~ 1.5Q; the remaining water is discharged.

6. The process according to claim 5, wherein the process is a process for enhanced autotrophic nitrogen removal in a municipal wastewater treatment plant by step feed multi-point internal recycle, characterized in that, The flocculent sludge concentration from the second anoxic zone to the second aerobic zone is 3000-6000mg / L.

7. The process according to claim 5, wherein the process is a process for enhanced autotrophic nitrogen removal of municipal wastewater by step feed multi-point reflux, characterized in that, The dissolved oxygen concentration in the first aerobic zone is 1.0-2.5mg / L.

8. The process according to claim 5, wherein the process is a process for enhanced autotrophic nitrogen removal of municipal wastewater by step feed multi-point reflux, characterized in that, The dissolved oxygen concentration in the second aerobic zone is 3-5mg / L.

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