Municipal sewage treatment device and method based on membrane aeration biological membrane and synchronous coagulation

Abstract

The invention discloses a municipal sewage treatment device and method based on a membrane aeration biological membrane and synchronous coagulation, and belongs to the technical field of sewage treatment.The municipal sewage treatment device is adopted for sewage treatment and comprises the following steps that S1, biological membrane hanging treatment is conducted on an aeration membrane in a membrane aeration biological membrane reactor; s2, conveying the municipal sewage into a membrane aeration bio-membrane reactor, carrying out experiments under different conditions, and determining hydraulic retention time, aeration pressure, and the type and dosage of a coagulant; and S3, presetting parameters of a treatment device according to a result of S2, and carrying out sequencing batch or continuous flow operation to complete sewage treatment. Municipal sewage is treated by combining a membrane aeration biological membrane and synchronous coagulation, the membrane aeration biological membrane can remove carbon and nitrogen, the coagulation can remove phosphorus and can remove part of residual organic matters, so that synchronous removal of carbon, nitrogen and phosphorus is realized, the outer layer of the membrane aeration biological membrane is further washed and stripped by adopting regular aeration to excessively proliferate the biological membrane, and long-term stable operation is further realized.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a municipal sewage treatment device and method based on membrane aeration biofilm and synchronous coagulation. Background Art

[0002] Anaerobic-anoxic-aerobic (A 2 O) Activated sludge process is widely used in municipal wastewater treatment to achieve simultaneous carbon, nitrogen and phosphorus removal, while municipal wastewater has a low carbon and nitrogen ratio, resulting in A 2 The O process has the problem of insufficient carbon source for anaerobic phosphorus release and anoxic denitrification, and additional degradable carbon source needs to be added to meet Class A and higher emission standards.

[0003] In the prior art, the traditional biofilm process usually uses inert materials such as polypropylene as carriers. Pollutants (such as organic matter, nitrogen and phosphorus, etc.) and dissolved oxygen in sewage diffuse from the mainstream liquid phase into the biofilm in the same direction, gradually forming aerobic, anoxic and anaerobic zones. During the diffusion of organic carbon sources in sewage into the biofilm, they first enter the aerobic zone and are consumed in large quantities by aerobic microorganisms, resulting in a reduction in the carbon source reaching the anoxic zone, which also limits the effect of denitrification. In addition, the oxygen utilization rate of the aeration or mechanical aeration used in traditional aerobic biological treatment technologies, including activated sludge and biofilm processes, is low, and most of the oxygen escapes from the water in the form of bubbles, resulting in high aeration energy consumption.

[0004] The membrane aeration biofilm process uses hollow fibers or flat aeration membranes as biofilm attachment carriers and provides oxygen required by microorganisms. Dissolved oxygen and carbon, nitrogen and phosphorus pollutants diffuse into the biofilm from both sides in different directions, which is easy to form a layered structure where the nitrification biofilm is enriched near the aeration membrane and the denitrification biofilm is enriched near the liquid mainstream. Organic matter first passes through the denitrification biofilm and is preferentially used as a carbon source for denitrification and denitrification. In addition, the simultaneous carbon removal and denitrification of low carbon-nitrogen ratio municipal sewage can be achieved without the need for an external carbon source. At the same time, the oxygen transfer efficiency of bubble-free aeration is high, so the aeration energy consumption is low. However, the traditional membrane aeration biofilm process only relies on cell synthesis and assimilation to absorb phosphorus, resulting in poor phosphorus removal.

[0005] Based on the above problems, a municipal sewage treatment device and method based on membrane aeration biofilm and synchronous coagulation is proposed. Summary of the invention

[0006] The object of the present invention is to provide a municipal sewage treatment device and method based on membrane aeration biofilm and synchronous coagulation to solve the problems in the background technology.

[0007] To achieve the above object, the present invention provides a municipal sewage treatment device based on membrane aeration biofilm and synchronous coagulation. The invention comprises a membrane aerated biofilm reactor and a coagulant liquid tank, wherein an aeration membrane assembly is arranged inside the membrane aerated biofilm reactor, the aeration membrane assembly is connected to a membrane aeration blower, the aeration membrane assembly is connected to an aeration flushing blower through a large bubble perforated aeration pipe below, a lower end circulation pipe of the membrane aerated biofilm reactor is connected to an upper end circulation pipe through a circulation pump, and the coagulant liquid tank is connected to a reactor body of the membrane aerated biofilm reactor or a water outlet pipe of the membrane aerated biofilm reactor through a dosing metering pump.

[0008] Preferably, a pressure gauge and a control valve are provided between the aeration membrane assembly and the membrane aeration blower, and between the large bubble perforated aeration pipe and the aeration flushing blower.

[0009] Based on the above processing device, a processing method is proposed, comprising the following steps: S1, performing biofilm treatment on the aeration membrane in the membrane aeration biofilm reactor; S2. Transporting municipal sewage to the membrane aeration biofilm reactor where biofilm has been successfully formed, conducting experiments under different conditions to determine the final hydraulic retention time, aeration pressure, type of coagulant and dosage; S3. Select batch operation or continuous flow operation according to actual conditions, preset various parameters of the treatment device according to the results obtained in S2, and complete sewage treatment according to the selected operation mode.

[0010] Preferably, the biofilm treatment of S1 is as follows: firstly, an influent containing only ammonia nitrogen is configured, and then the nitrifying biofilm is enriched on the surface of the aeration membrane in a directionally enhanced manner; after the nitrifying biofilm matures, an influent containing ammonia nitrogen and organic matter is configured or municipal sewage is directly used as the influent, and the denitrifying biofilm is enriched on the aeration membrane in a directionally enhanced manner, and finally a composite biofilm is attached to and grown on the surface of the aeration membrane, with the inner layer being mainly nitrifying bacteria and the outer layer being mainly denitrifying bacteria.

[0011] Preferably, when enriching nitrifying biofilm, the reactor inlet water is artificial water containing 50-100 mg / L ammonia nitrogen; when enriching denitrifying biofilm, the reactor inlet water is artificial water or municipal sewage with a COD concentration of 250-500 mg / L and an ammonia nitrogen concentration of 50-100 mg / L.

[0012] Preferably, in S2, the COD concentration of municipal sewage is 100-500 mg / L, the ammonia nitrogen concentration is 10-50 mg / L, the total nitrogen concentration is 15-60 mg / L, and the total phosphorus concentration is 3-10 mg / L.

[0013] Preferably, in S2, the experimental process is: 1) Set different hydraulic retention times and aeration pressures for the membrane aerated biofilm reactor, conduct operation experiments under different conditions, and select the final hydraulic retention time and aeration pressure based on the inlet and outlet water quality monitoring results; 2) The parameters of the membrane aerated biofilm reactor are set according to the hydraulic retention time and aeration pressure obtained in step 1) to treat the sewage. Then, a coagulation beaker experiment is performed on the effluent of the membrane aerated biofilm reactor under different coagulants and their dosage conditions. The final coagulant and the dosage of the coagulant are selected according to the water quality monitoring results.

[0014] Preferably, the hydraulic retention time is 3 to 24 hours and the aeration pressure is 5 to 20 kPa; The coagulant is an aluminum salt or an iron salt. The aluminum salt is an aluminum sulfate monomer, an aluminum chloride monomer, a polyaluminum sulfate or a polyaluminum chloride. The iron salt is a ferric sulfate monomer, a ferric chloride monomer, a polyferric sulfate or a polyferric chloride. The dosage of the coagulant is 10-200 mg / L.

[0015] Preferably, in S2, the final hydraulic retention time is 6 h, the aeration pressure is 10 kPa, the coagulant is polyaluminium chloride, and the dosage of the coagulant is 48 mg / L.

[0016] Preferably, in S3, the sewage treatment process is as follows: The membrane aeration blower is turned on to deliver air to the inner cavity of the aeration membrane module. The air inlet pressure is adjusted by the control valve. The air flows along the length direction of the aeration membrane module. The oxygen in the air selectively diffuses through the aeration membrane wall to the biofilm outside the aeration membrane. The ammonia nitrogen and organic matter in the municipal sewage diffuse from the liquid phase into the biofilm, and the denitrification and decarbonization reactions begin. The remaining tail gas is discharged through the pipeline; At the same time, the circulation pump is turned on to make the liquid in the reactor circulate along the length direction of the aeration membrane module to enhance the mixing effect and mass transfer efficiency; After the denitrification and decarbonization reactions are completed, coagulation operations and drainage and sludge removal operations are carried out according to the operating mode.

[0017] Preferably, the operation mode includes batch operation and continuous flow operation; During the sequencing batch operation, the outlet pipe of the membrane aerated biofilm reactor is connected to the outlet pool, the mud discharge pipe is connected to the mud discharge pump, and the coagulant liquid pool is connected to the membrane aerated biofilm reactor through the dosing metering pump; after the denitrification and carbon removal reaction is completed, the dosing metering pump is turned on to send the coagulant into the membrane aerated biofilm reactor, and the circulation pump is stopped after the coagulation reaction is completed. After standing, the outlet pump and the mud discharge pump are turned on to discharge water and mud; During the continuous flow operation, the outlet pipe of the membrane aerated biofilm reactor is connected to the sedimentation tank through an outlet pump, and the coagulant liquid tank is connected to the outlet pipe through a dosing metering pump; after the denitrification and carbon removal reaction is completed, the coagulant and the treated effluent are mixed in the outlet pipe and then flow into the sedimentation tank, and after mud and water separation in the sedimentation tank, the water is discharged and the sludge is discharged.

[0018] Preferably, in the sewage treatment of S3, the flushing aeration blower is turned on regularly to aerate and flush the over-proliferated outer denitrifying biofilm to peel it off. The detached biofilm is discharged through a sludge pump after static sedimentation in the reactor in the sequencing batch operation mode, and is discharged through a sludge pump after entering the sedimentation tank with the effluent in the continuous flow operation mode and undergoing mud-water separation.

[0019] Therefore, the municipal sewage treatment device and method based on membrane aeration biofilm and synchronous coagulation of the present invention have the following beneficial effects: (1) The present invention combines membrane aeration biofilm with synchronous coagulation to treat municipal sewage. The membrane aeration biofilm can remove carbon and nitrogen, and coagulation can remove phosphorus and some residual organic matter, thereby achieving synchronous carbon, nitrogen and phosphorus removal. Further, regular aeration flushing is used to peel off the outer layer of excessively proliferating biofilm, thereby achieving long-term stable operation.

[0020] (2) The method of the present invention was used to treat typical municipal sewage (COD concentration 258.1 mg / L, ammonia nitrogen concentration 30.6 mg / L, total nitrogen concentration 36.8 mg / L, total phosphorus concentration 5.3 mg / L), and the removal rates of COD, ammonia nitrogen, total nitrogen, and total phosphorus reached 81-83%, 84-87%, 76-82%, and 90-93%, respectively. The effluent COD, ammonia nitrogen, total nitrogen, and total phosphorus concentrations were 45-48 mg / L, 3.8-4.8 mg / L, 6.7-8.7 mg / L, and 0.39-0.48 mg / L, respectively, all of which met the Class A discharge standard. Compared with traditional activated sludge and biofilm processes, the total nitrogen removal rate can be significantly improved, and compared with the use of membrane aeration biofilm reactor alone, the total phosphorus removal rate can be significantly improved.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the sequencing batch membrane aeration biofilm and synchronous coagulation process in the present invention; Figure 2 It is a schematic diagram of the continuous flow membrane aeration biofilm and synchronous coagulation process in the present invention; Figure 3 This is a detection diagram of ammonia nitrogen removal and conversion during the nitrification biofilm enrichment process in step S1 of Example 1 of the present invention; Figure 4This is a detection diagram of nitrogen removal and conversion during the denitrification biofilm enrichment process in step S1 of Example 1 of the present invention; Figure 5 This is a detection diagram of COD removal during the enrichment of denitrifying biofilm in step S1 of Example 1 of the present invention; Figure 6 It is a detection diagram of the change of nitrogen conversion removal and organic matter removal with reaction time in the enrichment of denitrifying biofilm under the coexistence conditions of suspended sludge and biofilm in the eighth cycle in step S1 of Example 1 of the present invention; Figure 7 It is a detection diagram of the changes of nitrogen conversion removal and organic matter removal with reaction time under the condition of only biofilm in the enrichment of denitrifying biofilm in step S1 of Example 1 of the present invention in the 9th cycle; Figure 8 This is a test diagram of nitrogen removal and conversion of the membrane aeration biofilm reactor under different hydraulic retention times and optimal aeration pressure conditions in Example 1 of the present invention; Fig. 9 This is a detection diagram of COD removal of the membrane aeration biofilm reactor under different hydraulic retention times and optimal aeration pressure conditions in Example 1 of the present invention; Fig.10 This is a detection diagram of total phosphorus removal at different polyaluminium chloride addition molar ratios (Al:P) in the coagulation beaker experiment in Example 1 of the present invention; Fig.11 This is a detection diagram of COD removal when different polyaluminium chloride addition molar ratios (Al:P) are used in the coagulation beaker experiment in Example 1 of the present invention; Fig.12 This is a detection diagram of total phosphorus removal at different polyferric sulfate addition molar ratios (Fe:P) in the coagulation beaker experiment in Example 1 of the present invention; Fig.13 This is a detection diagram of COD removal when different polyferric sulfate addition molar ratios (Fe:P) are used in the coagulation beaker experiment in Example 1 of the present invention; Fig.14 This is a detection diagram of the final effluent COD and removal status in Example 1 of the present invention; Fig.15 This is a detection diagram of the final effluent ammonia nitrogen, total nitrogen and removal status in Example 1 of the present invention; Fig.16 This is a detection diagram of the final effluent total phosphorus and removal status in Example 1 of the present invention; Reference numerals: 1. Membrane aeration biofilm reactor; 2. Coagulant solution tank; 3. Water inlet tank; 4. Water inlet pump; 5. Aeration membrane assembly; 6. Aeration flushing blower; 7. Circulation pump; 8. Membrane aeration blower; 9. Pressure gauge; 10. Control valve; 11. Water outlet tank; 12. Water outlet pump; 13. Mud discharge pump; 14. Time controller; 15. Dosing metering pump; 16. Sedimentation tank. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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.

[0025] The present invention provides a municipal sewage treatment device based on membrane aeration biofilm and synchronous coagulation. The invention comprises a membrane aerated biofilm reactor 1 and a coagulant liquid tank 2, a water inlet pump 4 is arranged on the water inlet pipe, a hollow fiber aeration membrane module 5 is arranged inside the membrane aerated biofilm reactor 1, the aeration membrane module 5 is connected to a membrane aeration blower 8, a large bubble perforated aeration pipe is arranged below the aeration membrane module 5 and connected to an aeration flushing blower 6, and a lower end circulation pipe of the membrane aerated biofilm reactor 1 is connected to an upper end circulation pipe through a circulation pump 7 to promote mixing and mass transfer of liquid inside the reactor. A pressure gauge 9 and a control valve 10 are arranged between the aeration membrane module 5 and the membrane aeration blower 8, and between the large bubble perforated aeration pipe and the aeration flushing blower 6 for pressure regulation and monitoring.

[0026] like Figure 1 As shown, in the sequencing batch operation mode, the membrane aerated biofilm reactor 1 is connected to the water inlet tank 3 through the water inlet pipe, the water outlet pipe of the membrane aerated biofilm reactor 1 is connected to the water outlet tank 11 through the water outlet pump 12, the mud discharge pipe is connected to the mud discharge pump 13, and the coagulant liquid tank 2 is connected to the membrane aerated biofilm reactor 1 through the dosing metering pump 15; like Figure 2 As shown, in the continuous flow operation mode, the outlet pipe of the membrane aerated biofilm reactor 1 is connected to the sedimentation tank 16, and the coagulant liquid tank 2 is connected to the outlet pipe through the dosing metering pump 15; a sludge pump 13 is provided at the sludge discharge end of the sedimentation tank 16.

[0027] The above-mentioned water outlet pump 12, water inlet pump 4, mud discharge pump 13, control valve 10, membrane aeration blower 8 and dosing metering pump 15 are all controlled by the time controller 14, so as to realize automatic and stable operation of the system.

[0028] Example 1 The above treatment device is used to treat municipal sewage using a sequencing batch operation method as follows: S1. Performing biofilm treatment on the hollow fiber aeration membrane in the membrane aeration biofilm reactor; specifically: 1) Prepare artificial water containing 50~100mg / L ammonia nitrogen as the inlet water of the membrane aeration biofilm reactor, turn on the membrane aeration blower to directional strengthen the enrichment of nitrifying biofilm on the surface of the aeration membrane; test the removal and conversion of ammonia nitrogen in this step, the results are as follows Figure 3 As shown, the removal rate under the condition of 100 mg / L influent can reach more than 80%, indicating that after a short period of biofilm treatment, the membrane aeration biofilm exhibits good ammonia nitrogen removal efficiency, and the ammonia nitrogen is completely oxidized to nitrate nitrogen.

[0029] 2) After the nitrifying biofilm matures, artificial water with a COD concentration of 250-500 mg / L and an ammonia nitrogen concentration of 50-100 mg / L is used as the influent to directionally enhance the enrichment of the denitrifying biofilm on the aeration membrane. The treatment is carried out for 16 cycles, and sludge is discharged from the 9th cycle. Finally, a composite biofilm is attached to and grown on the surface of the aeration membrane. The inner layer of the structure is mainly composed of nitrifying bacteria, and the outer layer is mainly composed of denitrifying bacteria.

[0030] like Figure 4 As shown, the ammonia nitrogen removal rate was close to 100% when the suspended sludge and biofilm coexisted in the 1st to 8th cycles. The ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the effluent from the 9th to 16th cycles after the suspended sludge was discharged were all close to 0 mg / L, showing a good simultaneous nitrification and denitrification effect, indicating that a stable biofilm structure with inner nitrification and outer denitrification has been formed.

[0031] like Figure 5 As shown, the COD removal rate was stable at 83.5-86.0% when suspended sludge coexisted with biofilm in the 1st to 8th cycles. The COD removal rate decreased slightly in the 9th cycle just after the suspended sludge was discharged, and then gradually returned to the same level as the previous 8 cycles, indicating that the heterotrophic biofilm (common aerobic heterotrophic bacteria in the middle and anoxic denitrifying bacteria in the outer layer) had good activity, indicating that the membrane aerated biofilm has been rapidly enriched and domesticated successfully, and has good potential for simultaneous carbon removal and denitrification.

[0032] Figure 6 The results show that the nitrogen conversion removal and organic matter removal under the coexistence of suspended sludge and biofilm in the 8th cycle change with the reaction time. The results show that the ammonia nitrogen concentration shows a good linear downward trend with the reaction time before 6 hours, which conforms to the zero-order reaction kinetics, and the reaction rate constant is 8.07mg / L / h. The COD concentration shows an exponential downward trend with the reaction time, which conforms to the pseudo-first-order reaction kinetics, and the reaction rate constant is 0.35l / h.

[0033] Figure 7The results show that the nitrogen conversion removal and organic matter removal under the condition of biofilm only in the 9th cycle change with the reaction time. The results show that as the reaction time increases, the ammonia nitrogen concentration shows a good linear downward trend, which is consistent with the zero-order reaction kinetics, and the rate constant is 7.92 mg / L / h, which is similar to the 8th cycle, thus confirming that nitrification mainly occurs in the biofilm. The COD concentration shows an exponential downward trend with the extension of the reaction time, which is consistent with the pseudo-first-order reaction kinetics, and the rate constant is 0.2871 / h, which is slightly lower than the 8th cycle, which is related to the decrease in the coexistence of activated sludge and biofilm compared with the biomass of pure biofilm.

[0034] S2. Transporting municipal sewage to the membrane aeration biofilm reactor where biofilms have been successfully formed to carry out operation experiments under different hydraulic retention times and different aeration pressures; First, the hydraulic retention time was set to 24, 12, 8, 6, and 4 h, and the corresponding aeration pressure was 5, 7, 8, 10, and 12 kPa, respectively. The operation experiments were carried out respectively, and the nitrogen removal conversion was shown in the figure. Figure 8 As shown, the effluent ammonia nitrogen concentration of all experiments was between 0.88 and 5.0 mg / L, and the effluent total nitrogen concentration was between 6.37 and 10.68 mg / L, both of which could meet the Class A emission standards.

[0035] COD removal Fig. 9 As shown, the results show that the effluent COD concentration of all experiments fluctuates around 50 mg / L, which can meet the Class I B emission standard but cannot stably meet the Class I A emission standard.

[0036] According to the inlet and outlet water quality monitoring results, the final hydraulic retention time was selected as 6h and the aeration pressure was 10kPa; Then, the parameters of the membrane aerated biofilm reactor were set according to the hydraulic retention time of 6h and the aeration pressure of 10kPa, and a new round of sewage treatment was carried out. The effluent of the membrane aerated biofilm reactor was subjected to coagulation beaker experiments under different coagulants and their dosage conditions. According to the water quality monitoring results, Figure 10-13 As shown, the final coagulant selected was polyaluminium chloride, and the Al:P molar ratio was 2.27 (corresponding to a dosage of 48 mg / L).

[0037] S3. Select the operation mode of the membrane aerated biofilm reactor as sequencing batch operation, preset the parameters of the treatment device, and carry out the sewage treatment of the first operation cycle, as follows: 1) Start the water inlet pump, set the running time to 5 minutes, pump the municipal sewage in the water inlet tank into the membrane aerated biofilm reactor, and fill it to 90% of the predetermined full volume; 2) Turn on the membrane aeration blower to send air into the inner cavity of the aeration membrane assembly, adjust the air inlet pressure through the control valve, and the air flows along the length direction of the aeration membrane assembly. The oxygen in the air selectively penetrates the membrane wall into the biofilm outside the membrane, and ammonia nitrogen and organic matter diffuse into the biofilm from the liquid phase, starting the synchronous denitrification and carbon removal reaction process. The remaining tail gas is discharged into the atmosphere through the pipeline. At the same time, the circulation pump is turned on to promote mixing and mass transfer inside the reactor; 3) After the denitrification and carbon removal reaction is completed, stop the membrane aeration blower, start the dosing metering pump to send the polyaluminium chloride in the liquid pool into the reactor, stop the circulation pump after 15 minutes of coagulation reaction, and start the effluent pump to drain water and the sludge pump to discharge sludge after 15 minutes of static sedimentation to complete the sewage treatment.

[0038] The effluent after treatment was tested, and the removal of carbon, nitrogen and phosphorus was as follows: Figure 14-16 As shown, the results show that the concentrations of effluent total phosphorus, COD, ammonia nitrogen and total nitrogen are 0.39~0.48mg / L, 45.3~48mg / L, 3.8~4.8mg / L and 6.7~8.7mg / L, respectively, which can meet the Class A emission standards of urban sewage treatment plants. The corresponding removal rates of total phosphorus, COD, ammonia nitrogen and total nitrogen are 90.9~92.7%, 81.4~82.4%, 84.2~87.4% and 76.4-81.6%, respectively.

[0039] Example 2 The steps used in Example 2 are the same as those in Example 1, except that the coagulant used in the simultaneous coagulation is changed to polyferric sulfate. Fig.12 , Fig.13 , determine the molar ratio of Fe:P to be 2.5 (corresponding dosage is 62 mg / L).

[0040] The treated sewage was tested and the results showed that the concentrations of total phosphorus, COD, ammonia nitrogen and total nitrogen in the effluent were 0.32~0.45mg / L, 41.3~46.5mg / L, 3.5~4.5mg / L and 6.5~8.8mg / L, respectively, all meeting the Level A emission standards.

[0041] Therefore, the present invention provides a municipal sewage treatment device and method based on membrane aeration biofilm and synchronous coagulation, which combines membrane aeration biofilm and synchronous coagulation to treat municipal sewage. The membrane aeration biofilm can remove carbon and nitrogen, and coagulation can remove phosphorus and some residual organic matter, thereby achieving synchronous carbon, nitrogen and phosphorus removal. Further, regular aeration flushing is used to strip off the excessively proliferating biofilm on the outer layer of the membrane aeration biofilm, thereby achieving long-term stable operation.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A municipal sewage treatment device based on membrane aeration biofilm and synchronous coagulation, characterized in that: The invention comprises a membrane aerated biofilm reactor and a coagulant liquid tank, wherein an aeration membrane assembly is arranged inside the membrane aerated biofilm reactor, the aeration membrane assembly is connected to a membrane aeration blower, the aeration membrane assembly is connected to an aeration flushing blower through a large bubble perforated aeration pipe below, a lower end circulation pipe of the membrane aerated biofilm reactor is connected to an upper end circulation pipe through a circulation pump, and the coagulant liquid tank is connected to a reactor body of the membrane aerated biofilm reactor or a water outlet pipe of the membrane aerated biofilm reactor through a dosing metering pump.

2. A municipal sewage treatment device based on membrane aeration biofilm and synchronous coagulation according to claim 1, characterized in that: A pressure gauge and a control valve are provided between the aeration membrane assembly and the membrane aeration blower, and between the large bubble perforated aeration pipe and the aeration flushing blower.

3. A treatment method for a municipal sewage treatment device based on membrane aeration biofilm and synchronous coagulation according to any one of claims 1-2, characterized in that: The following steps are involved: S1, performing biofilm treatment on the aeration membrane in the membrane aeration biofilm reactor; S2. Transporting municipal sewage to the membrane aeration biofilm reactor where biofilm has been successfully formed, conducting experiments under different conditions to determine the final hydraulic retention time, aeration pressure, type of coagulant and dosage; S3. Select batch operation or continuous flow operation according to actual conditions, preset various parameters of the treatment device according to the results obtained in S2, and complete sewage treatment according to the selected operation mode.

4. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 3, characterized in that: The biofilm treatment of S1 is as follows: firstly, influent containing only ammonia nitrogen is configured, and then the nitrifying biofilm is enriched on the surface of the aeration membrane in a directionally enhanced manner. After the nitrifying biofilm matures, influent containing ammonia nitrogen and organic matter is configured or municipal sewage is directly used as influent, and the denitrifying biofilm is enriched on the aeration membrane in a directionally enhanced manner, so that a composite biofilm is finally attached to and grown on the surface of the aeration membrane.

5. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 4, characterized in that: When enriching nitrifying biofilm, the reactor inlet water is artificial water containing 50~100mg / L ammonia nitrogen; when enriching denitrifying biofilm, the reactor inlet water is artificial water or municipal sewage with COD concentration of 250~500mg / L and ammonia nitrogen concentration of 50~100mg / L.

6. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 3, characterized in that: In S2, the experimental process is: 1) Set different hydraulic retention times and aeration pressures for the membrane aerated biofilm reactor, conduct operation experiments under different conditions, and select the final hydraulic retention time and aeration pressure based on the inlet and outlet water quality monitoring results; 2) The parameters of the membrane aerated biofilm reactor are set according to the hydraulic retention time and aeration pressure obtained in step 1) to treat the sewage. Then, a coagulation beaker experiment is performed on the effluent of the membrane aerated biofilm reactor under different coagulants and their dosage conditions. The final coagulant and its dosage are selected according to the water quality monitoring results.

7. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 6, characterized in that: The hydraulic retention time is 3 to 24 hours and the aeration pressure is 5 to 20 kPa; The coagulant is an aluminum salt or an iron salt. The aluminum salt is an aluminum sulfate monomer, an aluminum chloride monomer, a polyaluminum sulfate or a polyaluminum chloride. The iron salt is a ferric sulfate monomer, a ferric chloride monomer, a polyferric sulfate or a polyferric chloride. The dosage of the coagulant is 10-200 mg / L.

8. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 3, characterized in that: In S3, the sewage treatment process is as follows: The membrane aeration blower is turned on to deliver air to the inner cavity of the aeration membrane module. The air inlet pressure is adjusted by the control valve. The air flows along the length direction of the aeration membrane module. The oxygen in the air selectively diffuses through the aeration membrane wall to the biofilm outside the aeration membrane. The ammonia nitrogen and organic matter in the municipal sewage diffuse from the liquid phase into the biofilm, and the denitrification and decarbonization reactions begin. The remaining tail gas is discharged through the pipeline; At the same time, the circulation pump is turned on to make the liquid in the reactor circulate along the length direction of the aeration membrane module to enhance the mixing effect and mass transfer efficiency; After the denitrification and decarbonization reactions are completed, coagulation operations and drainage and sludge removal operations are carried out according to the selected operating mode.

9. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 8, characterized in that: During the sequencing batch operation, the outlet pipe of the membrane aerated biofilm reactor is connected to the outlet pool through the outlet pump, the mud discharge pipe is connected to the mud discharge pump, and the coagulant liquid pool is connected to the membrane aerated biofilm reactor through the dosing metering pump; after the denitrification and carbon removal reaction is completed, the dosing metering pump is turned on to send the coagulant into the membrane aerated biofilm reactor, and the circulation pump is stopped after the coagulation reaction is completed. After standing, the outlet pump and the mud discharge pump are turned on to discharge water and mud; During the continuous flow operation, the outlet pipe of the membrane aerated biofilm reactor is connected to the sedimentation tank, and the coagulant liquid tank is connected to the outlet pipe through a dosing metering pump; the coagulant and the treated effluent are mixed in the outlet pipe and then flow into the sedimentation tank, and after mud and water are separated in the sedimentation tank, water and mud are discharged.

10. The method for treating municipal sewage based on membrane aeration biofilm and synchronous coagulation according to claim 3, characterized in that: In the wastewater treatment of S3, the flushing aeration blower is turned on regularly to aerate and flush the over-proliferated outer denitrifying biofilm.

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