A method for efficient denitrification and decarburization of biogas slurry from co-fermentation of kitchen waste and sludge

Abstract

The application discloses a method for efficient denitrification and decarburization of kitchen waste and sludge co-fermentation anaerobic digestion effluent, which removes part of COD and ammonia nitrogen in the influent sludge by using a first SNAD, and maintains a certain amount of free ammonia of a certain concentration due to the high concentration of ammonia nitrogen and the high pH of the influent, so as to maintain the inhibition effect on nitrifying bacteria and ensure the conversion of part of the ammonia nitrogen into nitrite nitrogen, and the high activity of anaerobic ammonia oxidation bacteria is ensured in the first SNAD by limiting the aeration amount, so that the ammonia nitrogen and nitrite can be further removed; the effluent enters a nitrification tank, and the ammonia nitrogen is nitrified into nitrate nitrogen under the condition of nitrifying bacteria and sufficient aeration amount, and then enters a denitrification tank, and the denitrification process is carried out under the condition of heterotrophic denitrifying bacteria and sufficient carbon source, so that most of the nitrate nitrogen in the system is converted into nitrogen gas and removed, finally, the clear liquid is discharged after being filtered by an MBR membrane in a membrane tank, so as to achieve the purpose of efficient denitrification and decarburization of kitchen waste anaerobic digestion effluent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a method for high-efficiency denitrification and decarburization of biogas slurry from co-fermentation of kitchen waste and sludge. BACKGROUND

[0002] Sludge is a byproduct of the sewage treatment process in sewage treatment plants. If it is discharged into the environment without proper treatment, it will cause serious secondary pollution to the environment. Both kitchen waste and sludge can be treated by anaerobic bacteria. The kitchen waste and sludge are fermented into biogas and residual material by anaerobic bacteria. The residual material is separated into residue and biogas slurry. The biogas slurry still contains high concentrations of COD and ammonia nitrogen, and the carbon-nitrogen ratio is low. It is difficult to treat the biogas slurry using traditional microbial denitrification technology. The effluent from the traditional biological denitrification process in sewage treatment plants cannot meet the discharge standard. The traditional process, such as nitrification and denitrification, has a long process flow and high energy consumption, which does not meet the development concept of environmental friendliness and energy saving. Therefore, the effluent needs to be further treated before it can be discharged.

[0003] In recent years, new biological denitrification technologies such as ANAMMOX technology have attracted much attention. ANAMMOX reaction is a process in which ammonia nitrogen and nitrite nitrogen are simultaneously removed to generate nitrogen gas under anaerobic autotrophic conditions. This technology does not require aeration or organic carbon source, and has the advantages of high efficiency, energy saving, environmental protection, etc. On this basis, scholars from various countries have proposed a variety of biological denitrification processes centered on ANAMMOX technology. Among them, the SNAD (Simultaneous partial Nitrification, Anammox and Denitrification) technology is highly praised because it can complete the low-energy denitrification and decarburization process in the same reactor. However, for biogas slurry from anaerobic digestion, only the SNAD system cannot achieve the discharge of biogas slurry, and further treatment is required. SUMMARY

[0004] The present application aims to provide a method for high-efficiency denitrification and decarburization of biogas slurry from co-fermentation of kitchen waste and sludge, which can ensure the stability of denitrification and decarburization efficiency, while reducing the operating power consumption and reagent consumption, so as to achieve high-efficiency and low-consumption treatment of total nitrogen in wastewater.

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is as follows: a method for high-efficiency denitrification and decarburization of biogas slurry from co-fermentation of kitchen waste and sludge, comprising two-stage serial simultaneous nitrification, ANAMMOX and denitrification steps, and nitrification, denitrification and membrane biological reaction steps.

[0006] The two-stage series nitrosation-anaerobic ammonia oxidation-denitrification (SNAD) process: ammonia nitrogen in the influent is converted into nitrite nitrogen by AOB, AnAOB utilizes the generated nitrite nitrogen and the original ammonia nitrogen in the influent to perform anaerobic ammonia oxidation reaction to generate nitrogen, at the same time, part of the nitrite nitrogen is converted into nitrate nitrogen by NOB, and DNB utilizes the COD in the influent and the nitrate nitrogen to perform denitrification reaction to generate nitrogen, the first-stage SNAD partially removes total nitrogen, and the second-stage SNAD further removes total nitrogen.

[0007] The nitration-denitrification-membrane biological reaction (O / A / O-MBR) process: part of the residual ammonia nitrogen in the effluent of the two-stage series nitrosation-anaerobic ammonia oxidation-denitrification is converted into nitrate nitrogen by the nitrosation process of AOB and the nitration process of NOB, DNB performs denitrification reaction under the action of anoxic and additional COD to remove total nitrogen, and then part of the COD is removed by the action of aerobic microorganisms, and the effluent is filtered by MBR to be discharged.

[0008] Further, the inoculated sludge in the two-stage series nitrosation-anaerobic ammonia oxidation-denitrification process comprises AnAOB, AOB and DNB, the abundance of AnAOB is not less than 3%, the filling ratio of the carrier filler is 25%-35%, the specific surface area of the filler is 550-900 m 2 / m 3 , the mixed liquid volatile suspended solid concentration MLVSS is 4000-5000 mg / L, the dissolved oxygen is controlled at 0.02-0.2 mg / L, the temperature is 31-35℃, the free ammonia in the first-stage nitrosation-anaerobic ammonia oxidation-denitrification process is controlled at 10-30 mg / L, and the free ammonia in the second-stage nitrosation-anaerobic ammonia oxidation-denitrification process is controlled at 1-5 mg / L.

[0009] Further, the inoculated sludge in the nitration-denitrification-membrane biological reaction process comprises AOB and NOB for the nitration tank and the membrane tank, and comprises DNB for the denitrification tank, the mixed liquid volatile suspended solid concentration MLVSS is controlled at 3000-5000 mg / L, the dissolved oxygen is controlled at 2-5 mg / L, and the temperature is 31-35℃ in the nitration process; the mixed liquid volatile suspended solid concentration MLVSS is controlled at 3000-5000 mg / L, the dissolved oxygen is controlled at 0.1 mg / L or below, and the temperature is 31-35℃ in the denitrification process; the membrane flux is controlled at 15 L / m 2 ·h or above, the effluent quality is that the ammonia nitrogen concentration is 5 mg / L or below, the total nitrogen concentration TN is 20 mg / L or below, and the COD concentration is 100-300 mg / L.

[0010] Further, the total hydraulic retention time of the two-stage series nitritation-anammox-denitrification step and the nitrification-denitrification-membrane biological reaction step is 96-144 h, wherein the hydraulic retention time of the two-stage series nitritation-anammox-denitrification step is controlled to be 48-72 h, and the hydraulic retention time of the nitrification-denitrification-membrane biological reaction step is controlled to be 48-72 h.

[0011] Further, the two-stage series nitritation-anammox-denitrification step is implemented in a two-stage SNAD system, which comprises a first SNAD-IFAS tank, a middle settling tank, a second SNAD-IFAS tank and a secondary settling tank, the first SNAD-IFAS tank contains a first stirring paddle and fillers, and a bottom aeration port is connected with a first aeration pump; the influent enters the first SNAD-IFAS tank first, the effluent of the first SNAD-IFAS tank enters the middle settling tank for sludge-water separation, the sludge enters a sludge tank and is returned to the first SNAD-IFAS tank through a first sludge return pump, the supernatant of the middle settling tank is pumped into the second SNAD-IFAS tank by a second influent pump, the second SNAD-IFAS tank contains a second stirring paddle and fillers, and a bottom aeration port is connected with a second aeration pump, the effluent of the second SNAD-IFAS tank enters the secondary settling tank for sludge-water separation, the sludge enters a sludge tank and is returned to the second SNAD-IFAS tank through a second sludge return pump, and the supernatant of the secondary settling tank is pumped into the first SNAD-IFAS tank by a return pump at a ratio of 1:1 of the influent flow rate of the first SNAD system.

[0012] Still further, the air pumped by the aeration pump is regulated by a flow meter to maintain the dissolved oxygen concentration in the first SNAD-IFAS tank at 0.1-0.2, and the dissolved oxygen concentration in the second SNAD-IFAS tank at 0.03-0.1, so that the internal microorganisms are in a micro-aeration environment and can remove most of the total nitrogen; the remaining ammonia nitrogen is used to maintain the free ammonia concentration in the first SNAD-IFAS tank and the second SNAD-IFAS tank, so as to inhibit the growth of nitrifying bacteria NOB without interfering with the growth of the main functional bacteria.

[0013] Still further, the middle settling tank and the secondary settling tank are both provided with a mud scraping plate, which is intermittently operated for 1 minute every 2 hours, so as to ensure that the sludge on the wall of the settling tank is removed while the effluent is still clear; the bottom slope of the middle settling tank and the secondary settling tank is set to be 45°-70°, so as to ensure that as much sludge as possible slides into the sludge tank and is returned to the first SNAD-IFAS tank and the second SNAD-IFAS tank.

[0014] Further, the nitrification-denitrification-membrane biological reaction step is implemented in an O / A / O-MBR system, the O / A / O-MBR system comprising a nitrification tank, a denitrification tank, a membrane tank and a dosing tank, the effluent of the secondary sedimentation tank is pumped into the nitrification tank by a third water inlet pump, the bottom aeration port of the nitrification tank is connected with a third aeration pump, the effluent enters the denitrification tank, the dosing tank contains sodium acetate solution, the sodium acetate solution enters the denitrification tank by a dosing pump, the denitrification tank is provided with a third stirring paddle, the effluent enters the membrane tank by a fourth water inlet pump, the bottom aeration port of the membrane tank is connected with a fourth aeration pump, the membrane tank is provided with MBR membranes, and a drainage pump is connected with the effluent port of the MBR membranes.

[0015] Further, the dissolved oxygen concentration in the nitrification tank and the membrane tank is controlled at 2.0-5.0 mg / L, and the dissolved oxygen concentration in the denitrification tank is controlled at 0.1 mg / L or lower, so as to ensure the normal survival and reproduction of nitrifying bacteria and denitrifying bacteria.

[0016] Further, the sodium acetate solution in the dosing tank is pumped in an amount not less than four times the nitrate nitrogen in the denitrification tank, so as to ensure that the nitrate nitrogen in the denitrification tank is converted into nitrogen gas by the denitrification process and removed.

[0017] Further, the MBR membranes are fixed on a stainless steel frame, the differential pressure of the membranes is monitored, and the membranes are cleaned regularly.

[0018] The present application can achieve the following technical effects due to the above technical solutions:

[0019] (1) The present application removes high-concentration ammonia nitrogen and COD contained in the co-fermentation anaerobic digestion biogas of kitchen waste + sludge by the two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step and the nitrification-denitrification-membrane biological reaction step, can ensure the stability of the denitrification and decarburization efficiency, and reduce the operation power consumption and reagent consumption, so that the total nitrogen in the wastewater is treated efficiently and at low cost.

[0020] (2) The present application controls the aeration amount in the SNAD system to ensure that a certain concentration of free ammonia exists in the system, which effectively inhibits the activity of nitrifying bacteria in the system, converts more ammonia nitrogen into nitrite nitrogen, and finally converts the nitrite nitrogen into nitrogen gas by anaerobic ammonia oxidation bacteria to be removed, thereby greatly improving the total nitrogen removal efficiency of the system and saving aeration energy consumption.

[0021] (3) The present application connects two-stage SNAD systems in series, and the water enters the first-stage SNAD system first, and then enters the second-stage SNAD system, and the effluent enters the O / A / O-MBR system, the residual ammonia nitrogen and nitrate nitrogen are converted into nitrogen gas through the nitrification and denitrification process for removal, and the effluent of the second-stage SNAD system is refluxed to the first-stage SNAD system at a flow rate of 1:1 of the influent of the first-stage SNAD system, for diluting the high-concentration influent, and the MBR membrane can reduce the turbidity of the effluent, so that the effluent meets the discharge requirements. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0023] Figure 1 It is a system structure diagram for efficient denitrification and decarburization of kitchen waste + sludge co-fermentation anaerobic digestion biogas liquid;

[0024] In the figure: 1 first water inlet pump; 2 first-stage SNAD-IFAS tank; 3 first stirring paddle; 4 intermediate sedimentation tank; 5 first aeration pump; 6 first sludge reflux pump; 7 second water inlet pump; 8 second-stage SNAD-IFAS tank; 9 second stirring paddle; 10 secondary sedimentation tank; 11 second aeration pump; 12 second sludge reflux pump; 13 third water inlet pump; 14 reflux pump; 15 nitrification tank; 16 third aeration pump; 17 denitrification tank; 18 third stirring paddle; 19 fourth water inlet pump; 20 dosing pump; 21 dosing tank; 22 membrane tank; 23 MBR membrane; 24 fourth aeration pump; 25 drainage pump. DETAILED DESCRIPTION

[0025] The principles of the present disclosure will be described below with reference to several example embodiments shown in the drawings. Although the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the description of these embodiments is only to enable those skilled in the art to better understand and implement the present disclosure, and does not limit the scope of the present disclosure in any way.

[0026] The term "comprising" and its variants as used in this text mean open inclusion, i.e. "including but not limited to". Unless specifically stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "first", "second", "third", "fourth" and the like can refer to different or the same objects. The following can also include other explicit and implicit definitions.

[0027] As Figure 1As shown, the embodiment provides a system for efficient denitrification and decarburization of kitchen waste + sludge co-fermentation anaerobic digestion effluent, which is used for implementing the above method; the system comprises a two-stage SNAD system and an O / A / O-MBR system, the two-stage SNAD system comprises a first water inlet pump, a second water inlet pump, a first-stage SNAD tank, a medium settling tank, a second-stage SNAD-IFAS tank, a secondary settling tank, a first aeration pump, a second aeration pump, a first stirring paddle, a second stirring paddle, a first sludge return pump, a second sludge return pump and a return pump, the first-stage SNAD-IFAS tank contains the first stirring paddle and fillers, a bottom aeration port of the first-stage SNAD-IFAS tank is connected with the first aeration pump, and incoming water enters the first-stage SNAD-IFAS tank, effluent of the first-stage SNAD-IFAS tank enters the medium settling tank for sludge-water separation, sludge enters a sludge tank and returns to the first-stage SNAD-IFAS tank through the first sludge return pump, supernatant of the medium settling tank is pumped into the second-stage SNAD-IFAS tank by the second water inlet pump, the second-stage SNAD-IFAS tank contains the second stirring paddle and fillers, a bottom aeration port of the second-stage SNAD-IFAS tank is connected with the second aeration pump, effluent of the second-stage SNAD-IFAS tank enters the secondary settling tank for sludge-water separation, sludge enters a sludge tank and returns to the second-stage SNAD-IFAS tank through the second sludge return pump, and a part of supernatant of the secondary settling tank is pumped into the first-stage SNAD-IFAS tank by the return pump.

[0028] The O / A / O-MBR system comprises a third water inlet pump, a fourth water inlet pump, a nitrification tank, a denitrification tank, a membrane tank, an MBR membrane, a third aeration pump, a fourth aeration pump, a third stirring paddle, a drainage pump, a dosing tank and a dosing pump, effluent of the secondary settling tank is pumped into the nitrification tank by the third water inlet pump, a bottom aeration port of the nitrification tank is connected with the third aeration pump, effluent enters the denitrification tank, the dosing tank contains sodium acetate solution, the sodium acetate solution enters the denitrification tank by the dosing pump, the denitrification tank contains the third stirring paddle, effluent enters the membrane tank by the fourth water inlet pump, a bottom aeration port of the membrane tank is connected with the fourth aeration pump, the membrane tank contains the MBR membrane, and the drainage pump is connected with an effluent port of the MBR membrane.

[0029] The filling amount of biological fillers in the first-stage SNAD-IFAS tank and the second-stage SNAD-IFAS tank is 20% to 40% of the total volume of each tank. The biological fillers can be modified biological suspended fillers WD-F10-4, and anaerobic ammonia oxidation biofilm grows on the surface of the fillers.

[0030] The active sludge filled in the first-stage SNAD-IFAS tank and the second-stage SNAD-IFAS tank is nitrosation bacteria, heterotrophic denitrifying bacteria and anaerobic ammonia oxidation bacteria. The active sludge filled in the nitrification tank and the membrane tank is nitrosation bacteria and nitrifying bacteria, and the active sludge filled in the denitrification tank is heterotrophic denitrifying bacteria.

[0031] The application discloses a method for efficiently removing nitrogen and carbon from kitchen waste and sludge co-fermentation anaerobic digestion effluent, and specifically realizes the following steps: removing part of total nitrogen from incoming water in a first SNAD-IFAS reaction tank through SNAD process, and converting part of ammonia nitrogen into nitrite nitrogen; the effluent enters a second SNAD-IFAS reaction tank, and about 80% of total nitrogen in the effluent is removed through SNAD process, and a certain ammonia nitrogen concentration is maintained to ensure that 5-20 mg / L of free ammonia exists in the first SNAD-IFAS tank and the second SNAD-IFAS tank to inhibit the activity of nitrifying bacteria, so that less nitrogen is converted into nitrate nitrogen; and finally, deep treatment is carried out in an O / A / O-MBR system to remove 99% of total nitrogen.

[0032] The application is used for treating kitchen waste and sludge co-fermentation anaerobic digestion effluent, and the specific implementation case is as follows: an organic waste comprehensive utilization treatment plant produces about 1300 t / d of effluent through anaerobic digestion every day, the water quality is as follows: ammonia nitrogen is about 1000-1100 mg / L, and COD is about 400-550 mg / L; the method is applied, two-stage series synchronous nitrosation-anaerobic ammonia oxidation-denitrification steps and nitrification-denitrification-membrane biological reaction steps are adopted, the hydraulic retention time of each step is 72 h, the effluent ammonia nitrogen is lower than 5 mg / L, the nitrite nitrogen is lower than 1 mg / L, the nitrate nitrogen is lower than 1 mg / L, and the removal rates of ammonia nitrogen and total nitrogen can both reach 99%.

[0033] The above description is only optional embodiments of the application, and is not used for limiting the application, and the application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the application should be included in the protection scope of the application.

[0034] Although the claims in the application are made for specific combinations of features, it should be understood that the scope of the application also includes any novel feature or any novel combination of features disclosed herein, whether explicitly or implicitly or any generalization thereof, regardless of whether he is involved in the same scheme in any currently claimed claim.

Claims

1. A method for efficient denitrification and decarburization of biogas slurry from co-fermentation of kitchen waste and sludge by anaerobic digestion, characterized in that, The two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step, the nitrification-denitrification-membrane biological reaction step, and the total hydraulic retention time of the two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step and the nitrification-denitrification-membrane biological reaction step. The two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step: ammonia nitrogen in the influent is converted into nitrite nitrogen under the action of nitrosation bacteria AOB, anaerobic ammonia oxidation bacteria AnAOB utilize the generated nitrite nitrogen and the original ammonia nitrogen in the influent to perform an anaerobic ammonia oxidation reaction to generate nitrogen, at the same time, part of the nitrite nitrogen is converted into nitrate nitrogen by nitrifying bacteria NOB, and heterotrophic denitrifying bacteria DNB utilize the COD in the influent and the nitrate nitrogen to perform a denitrification reaction to generate nitrogen. The nitrification-denitrification-membrane biological reaction step: part of the residual ammonia nitrogen in the effluent of the two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step is converted into nitrate nitrogen by the nitrosation process of nitrosation bacteria AOB and the nitrification process of nitrifying bacteria NOB, heterotrophic denitrifying bacteria DNB perform a denitrification reaction under the action of anoxic and additional COD to remove total nitrogen, and then part of the COD is removed by the action of aerobic microorganisms, and the effluent is filtered by an MBR membrane and discharged.

2. The method according to claim 1, wherein, The inoculated sludge in the two-stage series connection of the nitrosation-anaerobic ammonia oxidation-denitrification process comprises anaerobic ammonia oxidation bacteria AnAOB, nitrosation bacteria AOB and heterotrophic denitrification bacteria DNB, the process controls the abundance of the anaerobic ammonia oxidation bacteria AnAOB to be not less than 3%, the filling ratio of the carrier filler is 25%-35%, the specific surface area of the filler is 550-900 m 2 / m 3 , the mixed liquid volatile suspended solid concentration MLVSS is 4000-5000 mg / L, the dissolved oxygen is controlled to be 0.02-0.2 mg / L, the temperature is 31-35 DEG C, the free ammonia in the first-stage nitrosation-anaerobic ammonia oxidation-denitrification process is controlled to be 10-30 mg / L, and the free ammonia in the second-stage nitrosation-anaerobic ammonia oxidation-denitrification process is controlled to be 1-5 mg / L.

3. The method for high-efficiency denitrification and decarburization of the biogas slurry from the co-fermentation of kitchen waste and sludge according to claim 1, characterized in that, The sludge inoculated into the nitrification tank, the membrane tank in the nitrification-denitrification-membrane biological reaction step comprises nitrobacteria AOB and nitrobacteria NOB, the sludge inoculated into the denitrification tank comprises heterotrophic denitrifying bacteria DNB, the mixed liquid volatile suspended solid concentration MLVSS is controlled to be 3000-5000 mg / L in the nitrification step, the dissolved oxygen is controlled to be 2-5 mg / L, and the temperature is 31-35 ℃; the mixed liquid volatile suspended solid concentration MLVSS is controlled to be 3000-5000 mg / L in the denitrification step, the dissolved oxygen is controlled to be less than 0.1 mg / L, and the temperature is 31-35 ℃; and the membrane flux is controlled to be 15 L / m 2 ·h above, the effluent water quality ammonia nitrogen concentration is less than 5 mg / L, the total nitrogen concentration TN is less than 20 mg / L, and the COD concentration is 100-300 mg / L.

4. The method for high-efficiency denitrification and decarburization of the biogas slurry from the co-fermentation of kitchen waste and sludge according to claim 1, characterized in that, The total hydraulic retention time of the two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step and the nitrification-denitrification-membrane biological reaction step is 96-144h, wherein the hydraulic retention time of the two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step is controlled to be 48-72h, and the hydraulic retention time of the nitrification-denitrification-membrane biological reaction step is controlled to be 48-72h.

5. The method for high-efficiency denitrification and decarburization of the biogas slurry from the co-fermentation of kitchen waste and sludge according to claim 2, characterized in that, The two-stage series synchronization nitrosation-anaerobic ammonia oxidation-denitrification step is implemented in a two-stage SNAD system, the two-stage SNAD system comprises a first SNAD-IFAS tank, a middle settling tank, a second SNAD-IFAS tank and a secondary settling tank, the first SNAD-IFAS tank contains a first stirring paddle and filler, a bottom aeration port of the first SNAD-IFAS tank is connected with a first aeration pump, the incoming water first enters the first SNAD-IFAS tank, the effluent of the first SNAD-IFAS tank enters the middle settling tank for sludge-water separation, the sludge enters a sludge tank and is returned to the first SNAD-IFAS tank through a first sludge return pump, the supernatant of the middle settling tank is pumped into the second SNAD-IFAS tank by a second influent pump, the second SNAD-IFAS tank contains a second stirring paddle and filler, a bottom aeration port of the second SNAD-IFAS tank is connected with a second aeration pump, the effluent of the second SNAD-IFAS tank enters the secondary settling tank for sludge-water separation, the sludge enters a sludge tank and is returned to the second SNAD-IFAS tank through a second sludge return pump, and the supernatant of the secondary settling tank is pumped into the first SNAD-IFAS tank by a return pump at a ratio of 1:1 with respect to the influent flow rate of the first SNAD system.

6. The method for high-efficiency denitrification and decarburization of the biogas from the co-fermentation of kitchen waste and sludge according to claim 5, characterized in that, The air pumped by the aeration pump is regulated by a flow meter to maintain the dissolved oxygen concentration in the first SNAD-IFAS tank at 0.1-0.2mg / L and the dissolved oxygen concentration in the second SNAD-IFAS tank at 0.03-0.1mg / L.

7. The method according to claim 3, wherein, The nitrification-denitrification-membrane biological reaction step is implemented in an O / A / O-MBR system, the O / A / O-MBR system comprising a nitrification tank, a denitrification tank, a membrane tank and a dosing tank, the effluent of the secondary sedimentation tank being pumped into the nitrification tank by a third water inlet pump, the bottom aeration port of the nitrification tank being connected with a third aeration pump, the effluent entering the denitrification tank, the dosing tank containing sodium acetate solution, the sodium acetate solution entering the denitrification tank by a dosing pump, the denitrification tank having a third stirring paddle, the effluent entering the membrane tank by a fourth water inlet pump, the bottom aeration port of the membrane tank being connected with a fourth aeration pump, the membrane tank being immersed with MBR membranes, and a drainage pump being connected with the effluent port of the MBR membranes.

8. The method for efficient denitrification and decarburization of the biogas from the co-fermentation of kitchen waste and sludge by anaerobic digestion according to claim 7, characterized in that, The dissolved oxygen concentration in the nitrification tank and the membrane tank is controlled at 2.0-5.0 mg / L, and the dissolved oxygen concentration in the denitrification tank is controlled at below 0.1 mg / L.

9. The method for efficient nitrogen and carbon removal from anaerobic digestion slurry of kitchen waste and sludge co-fermentation according to claim 7, characterized in that, The sodium acetate solution in the dosing tank is pumped in an amount not less than four times the nitrate nitrogen in the denitrification tank.

10. The method for high-efficiency denitrification and decarburization of the biogas from the co-fermentation of kitchen waste and sludge according to claim 7, characterized in that, The MBR membranes are fixed on a stainless steel frame, and the membrane pressure difference is monitored.

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